Science.gov

Sample records for linear cell array

  1. Is cell migration or proliferation dominant in the formation of linear arrays of oligodendrocytes?

    PubMed

    Walsh, Darragh M; Röth, Philipp T; Holmes, William R; Landman, Kerry A; Merson, Tobias D; Hughes, Barry D

    2016-10-07

    Oligodendrocytes are the myelin-producing cells of the central nervous system that are responsible for electrically insulating axons to speed the propagation of electrical impulses. A striking feature of oligodendrocyte development within white matter is that the cell bodies of many oligodendrocyte progenitor cells become organised into discrete linear arrays of three or more cells before they differentiate into myelin-producing oligodendrocytes. These linear arrays align parallel to the direction of the axons within white matter tracts and are believed to play an important role in the co-ordination of myelination. Guided by experimental data on the abundance and composition of linear arrays in the corpus callosum of the postnatal mouse brain, we construct discrete and continuous models of linear array generation to specifically investigate the relative influence of cell migration, proliferation, differentiation and death of oligodendroglia upon the genesis of linear arrays during early postnatal development. We demonstrate that only models that incorporate significant cell migration can replicate all of the experimental observations on number of arrays, number of cells in arrays and total cell count of oligodendroglia within a given area of the corpus callosum. These models are also necessary to accurately reflect experimental data on the abundance of linear arrays composed of oligodendrocytes that derive from progenitors of different clonal origins.

  2. Directivity of linear microstrip arrays

    NASA Astrophysics Data System (ADS)

    Daniel, J. P.

    1987-08-01

    An analytical expression for the directivity is derived for uniformly excited linear arrays of rectangular printed antennas. Each antenna is assumed to radiate as two identical slots with a spacing which depends on the dielectric substrate. The directivity is plotted against distance between printed elements for two dielectric substrates, PTFE and alumina.

  3. Cell Searching and DoA Estimation Methods for Mobile Relay Stations with a Uniform Linear Array

    NASA Astrophysics Data System (ADS)

    Ko, Yo-Han; Park, Chang-Hwan; Kwon, Soon-Jik; Cho, Yong-Soo

    In this paper, cell searching and direction-of-arrival (DoA) estimation methods are proposed for mobile relay stations with a uniform linear arrays in OFDM-based cellular systems. The proposed methods can improve the performance of cell searching and DoA estimation, even when there exist symbol timing offsets among the signals received from adjacent base stations and Doppler frequency shifts caused by the movement of the mobile relay station. The performances and computational complexities of the proposed cell searching and DoA estimation methods are evaluated by computer simulation under a mobile WiMAX environment.

  4. Breadboard linear array scan imager program

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The performance was evaluated of large scale integration photodiode arrays in a linear array scan imaging system breadboard for application to multispectral remote sensing of the earth's resources. Objectives, approach, implementation, and test results of the program are presented.

  5. Fast time-domain modeling of fluid-coupled cMUT cells: from the single cell to the 1-D linear array element.

    PubMed

    Sénégond, Nicolas; Boulmé, Audren; Plag, Camille; Teston, Franck; Certon, Dominique

    2013-07-01

    We report a fast time-domain model of fluid-coupled cMUTs developed to predict the transient response-i.e., the impulse pressure response--of an element of a linear 1-D array. Mechanical equations of the cMUT diaphragm are solved with 2-D finite-difference schemes. The time-domain solving method is a fourth--order Runge-Kutta algorithm. The model takes into account the electrostatic nonlinearity and the contact with the bottom electrode when the membrane is collapsed. Mutual acoustic coupling between cells is introduced through the numerical implementation of analytical solutions of the impulse diffraction theory established in the case of acoustic sources with rectangular geometry. Processing times are very short: they vary from a few minutes for a single cell to a maximum of 30 min for one element of an array. After a description of the model, the impact of the nonlinearity and the pull-in/pull-out phenomena on the dynamic behavior of the cMUT diaphragm is discussed. Experimental results of mechanical displacements obtained by interferometric measurements and the acoustic pressure field are compared with simulations. Different excitation signals-high-frequency bandwidth pulses and toneburst excitations of varying central frequency-were chosen to compare theory with experimental results.

  6. Label-free high-throughput detection and quantification of circulating melanoma tumor cell clusters by linear-array-based photoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Hai, Pengfei; Zhou, Yong; Zhang, Ruiying; Ma, Jun; Li, Yang; Shao, Jin-Yu; Wang, Lihong V.

    2017-04-01

    Circulating tumor cell (CTC) clusters, arising from multicellular groupings in a primary tumor, greatly elevate the metastatic potential of cancer compared with single CTCs. High-throughput detection and quantification of CTC clusters are important for understanding the tumor metastatic process and improving cancer therapy. Here, we applied a linear-array-based photoacoustic tomography (LA-PAT) system and improved the image reconstruction for label-free high-throughput CTC cluster detection and quantification in vivo. The feasibility was first demonstrated by imaging CTC cluster ex vivo. The relationship between the contrast-to-noise ratios (CNRs) and the number of cells in melanoma tumor cell clusters was investigated and verified. Melanoma CTC clusters with a minimum of four cells could be detected, and the number of cells could be computed from the CNR. Finally, we demonstrated imaging of injected melanoma CTC clusters in rats in vivo. Similarly, the number of cells in the melanoma CTC clusters could be quantified. The data showed that larger CTC clusters had faster clearance rates in the bloodstream, which agreed with the literature. The results demonstrated the capability of LA-PAT to detect and quantify melanoma CTC clusters in vivo and showed its potential for tumor metastasis study and cancer therapy.

  7. Stripe filters on multispectral linear arrays

    NASA Technical Reports Server (NTRS)

    Hall, J. H.; Blaha, F. C.; Frias, B. R.; Halvis, J.; Hubbard, E.

    1982-01-01

    Dielectric interference filters deposited directly on top of existing 200 element charge coupled device linear imaging arrays were designed, fabricated and evaluated. The optical performance of the filters was verified with regard to crosstalk between adjacent detector elements. The filters showed an average in-band transmittance greater than 80% and a total out of band transmittance of less than 5%. Filter stability was adequate for operation in a space environment. The filter elements were definable in 12 to 25 micron element size compatible with existing silicon detectors. These type of measurement were made: (1) spectral transmission of the filter as deposited on witness plates; (2) spectral response of the silicon sensing device; (3) any optical interaction between filter and sensing device; (4) the response of the filter/sensor combination; and (5) repeatability and uniformity of filter characteristics. Detailed discussion of these evaluations are given.

  8. Artifact reduction through the use of concave linear arrays

    NASA Astrophysics Data System (ADS)

    Slayton, Michael H.; Roelike, Tim P.

    1992-11-01

    Ultrasonic imaging arrays are severely restricted in design and imaging quality by artifacts associated with the geometry of the arrays. Linear and convex linear arrays are limited by the appearance of side lobes and grating lobes in the images, which obscure diagnostically useful information. Limited access to parts of the body useful for accurate diagnosis (e.g., intercostal imaging) in many cases forces the use of phased arrays or mechanical arrays in place of linear and curved linear arrays. One of the ways to avoid the limitations and utilize the advantage of the curved linear configuration is to use a concave design. This paper compares the results of simulations of the concave and convex designs, and the degree of reduction of grating lobes. The simulation results are verified with beam plots of each design. Concave arrays are fabricated and clinical results are shown for intercostal and subcostal abdomen imaging.

  9. Linear stability of an accelerated wire array

    SciTech Connect

    Hammer, J H; Ryutov, D D

    1998-10-15

    The linear stability of an array of a large number of thin wires is considered. The wires form a cylindrical surface which is accelerated towards the axis under the action of a current excited in the array by an external source. General equations governing stability of this system are derived and a complete classification of all the modes present in such a system is presented. In agreement with an earlier analysis by Felber and Rostoker, it is shown that there exist two types of modes: medial modes, in which the wires experience deformation in the rz plane, and lateral modes, in which only a purely azimuthal deformation is present. For a given axial wave number k, the maximum growth rate for medial perturbations corresponds to a mode in which all the wires move "in phase" (an analog of an axisymmetric mode for a continuous cylindrical shell), whereas for the lateral perturbations the maximum growth rate corresponds to the opposite displacements of the neighboring wires. Numerical analysis of a dispersion relation for a broad range of modes is presented: Some limiting cases are discussed. In particular, it is shown that a traditional k1/2 scaling holds until surprisingly high wave numbers, even exceeding the inverse inter- wire distance. In the limit of long-wavelength perturbations, a model of a continuous shell becomes valid; the presence of the wires manifests itself in this model by a strong anisotropy of electrical conductivity, high along the wires and vanishing across the wires. The resulting modes differ considerably from the modes of a thin perfectly conducting shell. In particular, a new mode of "zonal flows" is identified.

  10. Linear-array ultrasonic waveguide transducer for under sodium viewing.

    SciTech Connect

    Sheen, S. H.; Chien, H. T.; Wang, K.; Lawrence, W. P.; Engel, D.; Nuclear Engineering Division

    2010-09-01

    In this report, we first present the basic design of a low-noise waveguide and its performance followed by a review of the array transducer technology. The report then presents the concept and basic designs of arrayed waveguide transducers that can apply to under-sodium viewing for in-service inspection of fast reactors. Depending on applications, the basic waveguide arrays consist of designs for sideway and downward viewing. For each viewing application, two array geometries, linear and circular, are included in design analysis. Methods to scan a 2-D target using a linear array waveguide transducer are discussed. Future plan to develop a laboratory array waveguide prototype is also presented.

  11. Linearly tapered slot antenna circular array for mobile communications

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Kelly, Eron; Lee, Richard Q.; Taub, Susan R.

    1993-01-01

    The design, fabrication and testing of a conformal K-band circular array is presented. The array consists of sixteen linearly tapered slot antennas (LTSA). It is fed by a 1:16 microstrip line power splitter via electromagnetic coupling. The array has an omni-directional pattern in the azimuth plane. In the elevation plane the beam is displaced above the horizon.

  12. Linear Array Ultrasonic Transducers: Sensitivity and Resolution Study

    NASA Astrophysics Data System (ADS)

    Kramb, V. A.

    2005-04-01

    The University of Dayton Research Institute (UDRI) under contract by the US Air Force has designed and integrated a fully automated inspection system for the inspection of turbine engines that incorporates linear phased array ultrasonic transducers. Phased array transducers have been successfully implemented into weld and turbine blade root inspections where the defect types are well known and characterized. Embedded defects in aerospace turbine engine components are less well defined, however. In order to determine the applicability of linear arrays to aerospace inspections the sensitivity of array transducers to embedded defects in engine materials must be characterized. In addition, the implementation of array transducers into legacy inspection procedures must take into account any differences in sensitivity between the array transducer and that of the single element transducer currently used. This paper discusses preliminary results in a study that compares the sensitivity of linear array and conventional single element transducers to synthetic hard alpha defects in a titanium alloy.

  13. Linear Array Ultrasonic Transducers: Sensitivity and Resolution Study

    SciTech Connect

    Kramb, V.A.

    2005-04-09

    The University of Dayton Research Institute (UDRI) under contract by the US Air Force has designed and integrated a fully automated inspection system for the inspection of turbine engines that incorporates linear phased array ultrasonic transducers. Phased array transducers have been successfully implemented into weld and turbine blade root inspections where the defect types are well known and characterized. Embedded defects in aerospace turbine engine components are less well defined, however. In order to determine the applicability of linear arrays to aerospace inspections the sensitivity of array transducers to embedded defects in engine materials must be characterized. In addition, the implementation of array transducers into legacy inspection procedures must take into account any differences in sensitivity between the array transducer and that of the single element transducer currently used. This paper discusses preliminary results in a study that compares the sensitivity of linear array and conventional single element transducers to synthetic hard alpha defects in a titanium alloy.

  14. Linear-array-based photoacoustic tomography for label-free high-throughput detection and quantification of circulating melanoma tumor cell clusters

    NASA Astrophysics Data System (ADS)

    Hai, Pengfei; Zhou, Yong; Zhang, Ruiying; Ma, Jun; Li, Yang; Wang, Lihong V.

    2017-03-01

    Circulating tumor cell (CTC) clusters arise from multicellular grouping in the primary tumor and elevate the metastatic potential by 23 to 50 fold compared to single CTCs. High throughout detection and quantification of CTC clusters is critical for understanding the tumor metastasis process and improving cancer therapy. In this work, we report a linear-array-based photoacoustic tomography (LA-PAT) system capable of label-free high-throughput CTC cluster detection and quantification in vivo. LA-PAT detects CTC clusters and quantifies the number of cells in them based on the contrast-to-noise ratios (CNRs) of photoacoustic signals. The feasibility of LA-PAT was first demonstrated by imaging CTC clusters ex vivo. LA-PAT detected CTC clusters in the blood-filled microtubes and computed the number of cells in the clusters. The size distribution of the CTC clusters measured by LA-PAT agreed well with that obtained by optical microscopy. We demonstrated the ability of LA-PAT to detect and quantify CTC clusters in vivo by imaging injected CTC clusters in rat tail veins. LA-PAT detected CTC clusters immediately after injection as well as when they were circulating in the rat bloodstreams. Similarly, the numbers of cells in the clusters were computed based on the CNRs of the photoacoustic signals. The data showed that larger CTC clusters disappear faster than the smaller ones. The results prove the potential of LA-PAT as a promising tool for both preclinical tumor metastasis studies and clinical cancer therapy evaluation.

  15. Synthesis of Taylor and Bayliss patterns for linear antenna arrays

    NASA Astrophysics Data System (ADS)

    Shelton, J. P.

    1981-08-01

    The history of synthesis techniques for designing linear antenna arrays with low sidelobe patterns is reviewed briefly, and the limitations that are encountered with very low sidelobes and/or small arrays are pointed out. Taylor's continuous aperture synthesis procedure is outlined, and a technique for transforming it for application to a discrete array is described. Discrete-array design equation for Taylor and Bayliss synthesis procedures are given. A set of programs for use on a programmable calculator are presented.

  16. Symmetry Groups for Linear Programming Relaxations of Orthogonal Array Problems

    DTIC Science & Technology

    2015-03-26

    Symmetry Groups for Linear Programming Relaxations of Orthogonal Array Problems THESIS MARCH 2015 David M. Arquette, Second Lieutenant, USAF AFIT-ENC...work of the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENC-MS-15-M-003 SYMMETRY GROUPS FOR LINEAR...PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT-ENC-MS-15-M-003 SYMMETRY GROUPS FOR LINEAR PROGRAMMING RELAXATIONS OF ORTHOGONAL ARRAY PROBLEMS David M

  17. Underwater Imaging Using a 1 × 16 CMUT Linear Array

    PubMed Central

    Zhang, Rui; Zhang, Wendong; He, Changde; Zhang, Yongmei; Song, Jinlong; Xue, Chenyang

    2016-01-01

    A 1 × 16 capacitive micro-machined ultrasonic transducer linear array was designed, fabricated, and tested for underwater imaging in the low frequency range. The linear array was fabricated using Si-SOI bonding techniques. Underwater transmission performance was tested in a water tank, and the array has a resonant frequency of 700 kHz, with pressure amplitude 182 dB (μPa·m/V) at 1 m. The −3 dB main beam width of the designed dense linear array is approximately 5 degrees. Synthetic aperture focusing technique was applied to improve the resolution of reconstructed images, with promising results. Thus, the proposed array was shown to be suitable for underwater imaging applications. PMID:26938536

  18. The Solution of Linear Complementarity Problems on an Array Processor.

    DTIC Science & Technology

    1981-01-01

    WISCONSIN-MADISON MATHEMATICS RESEARCH CENTER THE SOLUTION OF LINEAR COMPLEMENTARITY PROBLEMS ON AN ARRAY PROCESSOR C. W. Cryer* ’ 1 𔃼, P. M. Flanders...8217, D. J. Hunt+ , S. F. Reddaway+ , and J. Stansbury**’ 1 Technical Summary Report #2170 January 1981 ABSTRACT The Distributed Array Processor (DAP...manufactured by International Computers Limited is an array of 1 -bit 200-nanosecond processors. The Pilot DAP on which the present work was done is a 32

  19. A novel method to design sparse linear arrays for ultrasonic phased array.

    PubMed

    Yang, Ping; Chen, Bin; Shi, Ke-Ren

    2006-12-22

    In ultrasonic phased array testing, a sparse array can increase the resolution by enlarging the aperture without adding system complexity. Designing a sparse array involves choosing the best or a better configuration from a large number of candidate arrays. We firstly designed sparse arrays by using a genetic algorithm, but found that the arrays have poor performance and poor consistency. So, a method based on the Minimum Redundancy Linear Array was then adopted. Some elements are determined by the minimum-redundancy array firstly in order to ensure spatial resolution and then a genetic algorithm is used to optimize the remaining elements. Sparse arrays designed by this method have much better performance and consistency compared to the arrays designed only by a genetic algorithm. Both simulation and experiment confirm the effectiveness.

  20. Edge enhancement control in linear arrays of ungated field emitters

    NASA Astrophysics Data System (ADS)

    Harris, J. R.; Jensen, K. L.; Shiffler, D. A.

    2016-01-01

    In arrays of ungated field emitters, the field enhancement factor of each emitter decreases as the distance between the emitters decreases, an effect known as screening. At the edge of these arrays, emitters experience reduced screening, leading to higher field enhancement factors than emitters at the array center, causing nonuniform emission across the array. Here, we consider this effect in linear arrays of ungated field emitters spaced at distances comparable to their heights, which is the regime that generally maximizes their average current density. A Line Charge Model is used to assess the degree to which these edge effects propagate into the array interior, and to study the impact of varying the height, location, and tip radius of emitters at the ends of an array on the edge enhancement. It is shown that each of these techniques can accomplish this edge enhancement control, but each has advantages and disadvantages that will be discussed.

  1. Linear colloidal crystal arrays by electrohydrodynamic printing

    NASA Astrophysics Data System (ADS)

    Poon, H. F.; Saville, D. A.; Aksay, I. A.

    2008-09-01

    We use electrohydrodynamic jets of colloidal suspensions to produce arrays of colloidal crystalline stripes on surfaces. A critical factor in maintaining a stable jet is the distance of separation between the nozzle and the surface. Colloidal crystalline stripes are produced as two wetting lines of the deployed suspension merge during drying. To ensure that the two wetting lines merge, the "deployed-line-width" to "particle size" ratio is kept below a critical value so that the capillary forces overcome the frictional forces between the particles and the substrate.

  2. Reconstruction Techniques for Sparse Multistatic Linear Array Microwave Imaging

    SciTech Connect

    Sheen, David M.; Hall, Thomas E.

    2014-06-09

    Sequentially-switched linear arrays are an enabling technology for a number of near-field microwave imaging applications. Electronically sequencing along the array axis followed by mechanical scanning along an orthogonal axis allows dense sampling of a two-dimensional aperture in near real-time. In this paper, a sparse multi-static array technique will be described along with associated Fourier-Transform-based and back-projection-based image reconstruction algorithms. Simulated and measured imaging results are presented that show the effectiveness of the sparse array technique along with the merits and weaknesses of each image reconstruction approach.

  3. Jet Noise Source Localization Using Linear Phased Array

    NASA Technical Reports Server (NTRS)

    Agboola, Ferni A.; Bridges, James

    2004-01-01

    A study was conducted to further clarify the interpretation and application of linear phased array microphone results, for localizing aeroacoustics sources in aircraft exhaust jet. Two model engine nozzles were tested at varying power cycles with the array setup parallel to the jet axis. The array position was varied as well to determine best location for the array. The results showed that it is possible to resolve jet noise sources with bypass and other components separation. The results also showed that a focused near field image provides more realistic noise source localization at low to mid frequencies.

  4. Linear antenna array optimization using flower pollination algorithm.

    PubMed

    Saxena, Prerna; Kothari, Ashwin

    2016-01-01

    Flower pollination algorithm (FPA) is a new nature-inspired evolutionary algorithm used to solve multi-objective optimization problems. The aim of this paper is to introduce FPA to the electromagnetics and antenna community for the optimization of linear antenna arrays. FPA is applied for the first time to linear array so as to obtain optimized antenna positions in order to achieve an array pattern with minimum side lobe level along with placement of deep nulls in desired directions. Various design examples are presented that illustrate the use of FPA for linear antenna array optimization, and subsequently the results are validated by benchmarking along with results obtained using other state-of-the-art, nature-inspired evolutionary algorithms such as particle swarm optimization, ant colony optimization and cat swarm optimization. The results suggest that in most cases, FPA outperforms the other evolutionary algorithms and at times it yields a similar performance.

  5. Reconstruction techniques for sparse multistatic linear array microwave imaging

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; Hall, Thomas E.

    2014-06-01

    Sequentially-switched linear arrays are an enabling technology for a number of near-field microwave imaging applications. Electronically sequencing along the array axis followed by mechanical scanning along an orthogonal axis allows dense sampling of a two-dimensional aperture in near real-time. The Pacific Northwest National Laboratory (PNNL) has developed this technology for several applications including concealed weapon detection, groundpenetrating radar, and non-destructive inspection and evaluation. These techniques form three-dimensional images by scanning a diverging beam swept frequency transceiver over a two-dimensional aperture and mathematically focusing or reconstructing the data into three-dimensional images. Recently, a sparse multi-static array technology has been developed that reduces the number of antennas required to densely sample the linear array axis of the spatial aperture. This allows a significant reduction in cost and complexity of the linear-array-based imaging system. The sparse array has been specifically designed to be compatible with Fourier-Transform-based image reconstruction techniques; however, there are limitations to the use of these techniques, especially for extreme near-field operation. In the extreme near-field of the array, back-projection techniques have been developed that account for the exact location of each transmitter and receiver in the linear array and the 3-D image location. In this paper, the sparse array technique will be described along with associated Fourier-Transform-based and back-projection-based image reconstruction algorithms. Simulated imaging results are presented that show the effectiveness of the sparse array technique along with the merits and weaknesses of each image reconstruction approach.

  6. Application of visible linear array technology to earth observation sensors

    NASA Technical Reports Server (NTRS)

    Noll, R. E.; Tracy, R. A.

    1975-01-01

    The present paper identifies the systems engineering aspects of applying solid-state technology to earth observations applications being traditionally performed by point (or multiple-point) detector line scanned mechanisms. It is shown that the translation from a basically serial data flow point-detector mechanically-scanned sensor to a solid state highly parallel linear-array pushbroom sensor results in minimizing mechanical complexity and maximizing electronics complexity, with increased demands upon optical performance in some applications. Technical aspects relevant to highly parallel photodiode linear-array pushbroom applications are discussed. Examples of systems engineering applications are provided.

  7. Multispectral linear array. [for free-flyer satellite and Shuttle

    NASA Technical Reports Server (NTRS)

    Richard, H. L.; Speaker, E. E.

    1982-01-01

    The Multispectral Linear Array (MLA) is a solid-state earth imagery radiometer operating in the 'push-broom' mode and using a focal plane containing multiple spectral band linear detector arrays. The MLA sensor offers the capability for increased spatial and spectral resolution with multiple selectable bands and in-orbit operation flexibility. Both free-flyer (satellite) and Shuttle-attached instrument designs have been studied. Four Shuttle-attached MLA instrument design studies were initiated in 1982, and the concepts resulting from these studies are described.

  8. Position sensor for linear synchronous motors employing halbach arrays

    DOEpatents

    Post, Richard Freeman

    2014-12-23

    A position sensor suitable for use in linear synchronous motor (LSM) drive systems employing Halbach arrays to create their magnetic fields is described. The system has several advantages over previously employed ones, especially in its simplicity and its freedom from being affected by weather conditions, accumulated dirt, or electrical interference from the LSM system itself.

  9. Spaceborne linear arrays of 512×3 microbolometers

    NASA Astrophysics Data System (ADS)

    Ngo Phong, Linh; Pancrati, Ovidiu; Marchese, Linda; Châteauneuf, François

    2013-03-01

    Details on the first linear arrays of 512×3 VOx microbolometers operating in space are reported. Arrays of this format are suited for remote sensing where relative motion between the spacecraft and target provides an inherent scanning mechanism. To take full advantage of the linear format, the array is built on a custom readout electronics that enables simultaneous integration of all pixels for scanning periods of up to 140 ms. The output signal from each pixel is digitized to 14 bits using a voltage-to-frequency conversion mechanism. Two arrays, integrated into two spectrally distinct radiometric packages, provide for coregistration of infrared images in three bands centered at 3.8, 10.85, and 11.85 μm for the retrieval of fire and sea surface temperatures. Analysis of the downlinked data confirms the reliable in-orbit operation and consistency with pre-launch characteristics for both arrays. Algorithms have been developed to perform post processing and absolute radiometric calibration of images in all bands. Image deconvolution using Wiener filtering was found effective in recovering the signal loss incurred in the active pixels when observing high temperature events. The in-flight gain and offset values were evaluated for all pixels by means of deep space measurements and cross calibration with reference spaceborne sensors. Preliminary assessment of the images calibrated using these values showed that they are in agreement with those retrieved from GOES sensor.

  10. Very High Frequency (Beyond 100 MHz) PZT Kerfless Linear Arrays

    PubMed Central

    Wu, Da-Wei; Zhou, Qifa; Geng, Xuecang; Liu, Chang-Geng; Djuth, Frank; Shung, K. Kirk

    2010-01-01

    This paper presents the design, fabrication, and measurements of very high frequency kerfless linear arrays prepared from PZT film and PZT bulk material. A 12-µm PZT thick film fabricated from PZT-5H powder/solution composite and a piece of 15-µm PZT-5H sheet were used to fabricate 32-element kerfless high-frequency linear arrays with photolithography. The PZT thick film was prepared by spin-coating of PZT sol-gel composite solution. The thin PZT-5H sheet sample was prepared by lapping a PZT-5H ceramic with a precision lapping machine. The measured results of the 2 arrays were compared. The PZT film array had a center frequency of 120 MHz, a bandwidth of 60% with a parylene matching layer, and an insertion loss of 41 dB. The PZT ceramic sheet array was found to have a center frequency of 128 MHz with a poorer bandwidth (40% with a parylene matching layer) but a better sensitivity (28 dB insertion loss). PMID:19942516

  11. Linear laser diode arrays for improvement in optical disk recording

    NASA Technical Reports Server (NTRS)

    Alphonse, G. A.; Carlin, D. B.; Connolly, J. C.

    1990-01-01

    The development of individually addressable laser diode arrays for multitrack magneto-optic recorders for space stations is discussed. Three multi-element channeled substrate planar (CSP) arrays with output power greater than 30 mW with linear light vs current characteristics and stable single mode spectra were delivered to NASA. These devices have been used to demonstrate for the first time the simultaneous recording of eight data tracks on a 14-inch magneto-optic erasable disk. The yield of these devices is low, mainly due to non-uniformities inherent to the LPE growth that was used to fabricate them. The authors have recently developed the inverted CSP, based on the much more uniform MOCVD growth techniques, and have made low threshold quantum well arrays requiring about three times less current than the CSP to deliver 30 mW CW in a single spatial mode. The inverted CSP is very promising for use in space flight recorder applications.

  12. Inverted Linear Halbach Array for Separation of Magnetic Nanoparticles.

    PubMed

    Ijiri, Y; Poudel, C; Williams, P S; Moore, L R; Orita, T; Zborowski, M

    2013-07-01

    A linear array of Nd-Fe-B magnets has been designed and constructed in an inverted Halbach configuration for use in separating magnetic nanoparticles. The array provides a large region of relatively low magnetic field, yet high magnetic field gradient in agreement with finite element modeling calculations. The magnet assembly has been combined with a flow channel for magnetic nanoparticle suspensions, such that for an appropriate distance away from the assembly, nanoparticles of higher moment aggregate and accumulate against the channel wall, with lower moment nanoparticles flowing unaffected. The device is demonstrated for iron oxide nanoparticles with diameters of ~ 5 and 20 nm. In comparison to other approaches, the inverted Halbach array is more amenable to modeling and to scaling up to preparative quantities of particles.

  13. Inverted Linear Halbach Array for Separation of Magnetic Nanoparticles

    PubMed Central

    Ijiri, Y.; Poudel, C.; Williams, P.S.; Moore, L.R.; Orita, T.; Zborowski, M.

    2014-01-01

    A linear array of Nd-Fe-B magnets has been designed and constructed in an inverted Halbach configuration for use in separating magnetic nanoparticles. The array provides a large region of relatively low magnetic field, yet high magnetic field gradient in agreement with finite element modeling calculations. The magnet assembly has been combined with a flow channel for magnetic nanoparticle suspensions, such that for an appropriate distance away from the assembly, nanoparticles of higher moment aggregate and accumulate against the channel wall, with lower moment nanoparticles flowing unaffected. The device is demonstrated for iron oxide nanoparticles with diameters of ~ 5 and 20 nm. In comparison to other approaches, the inverted Halbach array is more amenable to modeling and to scaling up to preparative quantities of particles. PMID:25382864

  14. Optical butting of linear infrared detector array for pushbroom imager

    NASA Astrophysics Data System (ADS)

    Qiu, Minpu; Ma, Wenpo

    2017-02-01

    High resolution and large FOV represents the developing trends of space optical imaging systems, Considering the characters of infrared optical systems, A low cost and low technical risk method of optical butting concept which offer the promise of butting smaller arrays into long linear detector assemblies is presented in this paper, the design method of optical butting is described, and a hypothetical system is demonstrated as well.

  15. On the design and implementation of linear differential microphone arrays.

    PubMed

    Chen, Jingdong; Benesty, Jacob; Pan, Chao

    2014-12-01

    Differential microphone array (DMA), a particular kind of sensor array that is responsive to the differential sound pressure field, has a broad range of applications in sound recording, noise reduction, signal separation, dereverberation, etc. Traditionally, an Nth-order DMA is formed by combining, in a linear manner, the outputs of a number of DMAs up to (including) the order of N - 1. This method, though simple and easy to implement, suffers from a number of drawbacks and practical limitations. This paper presents an approach to the design of linear DMAs. The proposed technique first transforms the microphone array signals into the short-time Fourier transform (STFT) domain and then converts the DMA beamforming design to simple linear systems to solve. It is shown that this approach is much more flexible as compared to the traditional methods in the design of different directivity patterns. Methods are also presented to deal with the white noise amplification problem that is considered to be the biggest hurdle for DMAs, particularly higher-order implementations.

  16. Solar cell array interconnects

    DOEpatents

    Carey, Paul G.; Thompson, Jesse B.; Colella, Nicolas J.; Williams, Kenneth A.

    1995-01-01

    Electrical interconnects for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb-Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb-Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value.

  17. Solar cell array interconnects

    DOEpatents

    Carey, P.G.; Thompson, J.B.; Colella, N.J.; Williams, K.A.

    1995-11-14

    Electrical interconnects are disclosed for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb-Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb-Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value. 4 figs.

  18. Double interconnection fuel cell array

    DOEpatents

    Draper, Robert; Zymboly, Gregory E.

    1993-01-01

    A fuel cell array (10) is made, containing number of tubular, elongated fuel cells (12) which are placed next to each other in rows (A, B, C, D), where each cell contains inner electrodes (14) and outer electrodes (18 and 18'), with solid electrolyte (16 and 16') between the electrodes, where the electrolyte and outer electrode are discontinuous, having two portions, and providing at least two opposed discontinuities which contain at least two oppositely opposed interconnections (20 and 20') contacting the inner electrode (14), each cell (12) having only three metallic felt electrical connectors (22) which contact surrounding cells, where each row is electrically connected to the other.

  19. Performance bounds for modal analysis using sparse linear arrays

    NASA Astrophysics Data System (ADS)

    Li, Yuanxin; Pezeshki, Ali; Scharf, Louis L.; Chi, Yuejie

    2017-05-01

    We study the performance of modal analysis using sparse linear arrays (SLAs) such as nested and co-prime arrays, in both first-order and second-order measurement models. We treat SLAs as constructed from a subset of sensors in a dense uniform linear array (ULA), and characterize the performance loss of SLAs with respect to the ULA due to using much fewer sensors. In particular, we claim that, provided the same aperture, in order to achieve comparable performance in terms of Cramér-Rao bound (CRB) for modal analysis, SLAs require more snapshots, of which the number is about the number of snapshots used by ULA times the compression ratio in the number of sensors. This is shown analytically for the case with one undamped mode, as well as empirically via extensive numerical experiments for more complex scenarios. Moreover, the misspecified CRB proposed by Richmond and Horowitz is also studied, where SLAs suffer more performance loss than their ULA counterpart.

  20. Flexible micromirror linear array for high-resolution projection display

    NASA Astrophysics Data System (ADS)

    Picard, Francis; Campillo, Celine; Pope, Timothy D.; Niall, Keith K.; Peppler, Philipp W.; Larouche, Carl; Jerominek, Hubert

    2003-01-01

    The visual displays of contemporary military flight simulators lack adequate definition to represent scenes in basic fast-jet fighter tasks. For example, air-to-air and air-to-ground targets are not projected with sufficient contrast and resolution for a pilot to perceive aspect, aspect rate and object detail at real world slant ranges. Simulator display geometries require the development of ultra-high resolution projectors with greater than 20 megapixel resolution at 60 Hz frame rate. A new micromirror device has been developed to address this requirement; it is able to modulate light intensity in an analog fashion with switching times shorter than 5 μs. When combined with a scanner, a microlaser and Schlieren optics, a linear array of these flexible micromirrors can display images composed of thousands of lines at a frame rate of 60 Hz. The approach selected for light modulation and the micromirror fabrication process flow are reviewed. Static and dynamic performances of these electrostatic MOEMS are described. Preliminary results following the integration of the described modulator into a projector prototype are reported. Developments toward a fully addressable 2000 × 1 flexible micromirror array are presented. The specifications and design of the CMOS circuit required to control this micromirror array are described. Packaging issues related to these large arrays are discussed.

  1. Spatial Signature Estimation with an Uncalibrated Uniform Linear Array

    PubMed Central

    Cao, Xiang; Xin, Jingmin; Nishio, Yoshifumi; Zheng, Nanning

    2015-01-01

    In this paper, the problem of spatial signature estimation using a uniform linear array (ULA) with unknown sensor gain and phase errors is considered. As is well known, the directions-of-arrival (DOAs) can only be determined within an unknown rotational angle in this array model. However, the phase ambiguity has no impact on the identification of the spatial signature. Two auto-calibration methods are presented for spatial signature estimation. In our methods, the rotational DOAs and model error parameters are firstly obtained, and the spatial signature is subsequently calculated. The first method extracts two subarrays from the ULA to construct an estimator, and the elements of the array can be used several times in one subarray. The other fully exploits multiple invariances in the interior of the sensor array, and a multidimensional nonlinear problem is formulated. A Gauss–Newton iterative algorithm is applied for solving it. The first method can provide excellent initial inputs for the second one. The effectiveness of the proposed algorithms is demonstrated by several simulation results. PMID:26076405

  2. Combustion of strongly-interacting linear droplet arrays

    SciTech Connect

    Miyasaka, K.; Law, C.K.

    1981-01-01

    Experiments were conducted to study the droplet vaporization rate, the gross flame characteristics, and the effect of buoyancy of closely-spaced, strongly-interacting, linear arrays of two and three droplets. Intensity of buoyancy was controlled by varying the pressure and oxygen concentration within the combustion chamber. Results show that the burning process depends on the initial array configuration, that the droplet vaporization rate does not follow the d/sup 2/-law, that the measured rate is substantially below the existing theoretical predictions except towards the latter part of the droplet lifetime at which good agreement exists, and that bouyancy can significantly enhance the vaporization rate to compensate for the interference effect. 21 refs.

  3. Automated control of linear constricted plasma source array

    DOEpatents

    Anders, Andre; Maschwitz, Peter A.

    2000-01-01

    An apparatus and method for controlling an array of constricted glow discharge chambers are disclosed. More particularly a linear array of constricted glow plasma sources whose polarity and geometry are set so that the contamination and energy of the ions discharged from the sources are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The quality of film along deposition "tracks" opposite the plasma sources can be measured and compared to desired absolute or relative values by optical and/or electrical sensors. Plasma quality can then be adjusted by adjusting the power current values, gas feed pressure/flow, gas mixtures or a combination of some or all of these to improve the match between the measured values and the desired values.

  4. Linearity Testing of Photovoltaic Cells

    SciTech Connect

    Pinegar, S.; Nalley, D.; Emery, K.

    2006-01-01

    Photovoltaic devices are rated in terms of their power output or efficiency with respect to a specific spectrum, total irradiance, and temperature. In order to rate photovoltaic devices, a reference detector whose response is linear with total irradiance is needed. This procedure documents a procedure to determine if a detector is linear over the irradiance range of interest. Testing the short circuit current versus the total irradiance is done by illuminating a reference cell candidate with two lamps that are fitted with programmable filter wheels. The purpose is to reject nonlinear samples as determined by national and international standards from being used as primary reference cells. A calibrated linear reference cell tested by the two lamp method yields a linear result.

  5. Design tradeoffs for a Multispectral Linear Array (MLA) instrument

    NASA Technical Reports Server (NTRS)

    Mika, A. M.

    1982-01-01

    The heart of the multispectral linear array (MLA) design problem is to develop an instrument concept which concurrently provides a wide field-of-view with high resolution, spectral separation with precise band-to band registration, and excellent radiometric accuracy. Often, these requirements have conflicting design implications which can only be resolved by careful tradeoffs that consider performance, cost, fabrication feasibility and development risk. The key design tradeoffs for an MLA instrument are addressed, and elements of a baseline instrument concept are presented.

  6. Space Power Amplification with Active Linearly Tapered Slot Antenna Array

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1993-01-01

    A space power amplifier composed of active linearly tapered slot antennas (LTSA's) has been demonstrated and shown to have a gain of 30 dB at 20 GHz. In each of the antenna elements, a GaAs monolithic microwave integrated circuit (MMIC) three-stage power amplifier is integrated with two LTSA's. The LTSA and the MMIC power amplifier has a gain of 11 dB and power added efficiency of 14 percent respectively. The design is suitable for constructing a large array using monolithic integration techniques.

  7. Spatial frequency multiplier with active linearly tapered slot antenna array

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1994-01-01

    A frequency multiplier with active linearly tapered slot antennas (LTSA's) has been demonstrated at the second harmonic frequency. In each antenna element, a GaAs monolithic microwave integrated circuit (MMIC) distributed amplifier is integrated with two LTSA's. The multiplier has a very wide bandwidth and large dynamic range. The fundamental-to-second harmonic conversion efficiency is 8.1 percent. The spatially combined second harmonic signal is 50 dB above the noise level. The design is suitable for constructing a large array using monolithic integration techniques.

  8. Wake Vortex Detection: Phased Microphone vs. Linear Infrasonic Array

    NASA Technical Reports Server (NTRS)

    Shams, Qamar A.; Zuckerwar, Allan J.; Sullivan, Nicholas T.; Knight, Howard K.

    2014-01-01

    infrasonic array at the Newport News-Williamsburg International Airport early in the year 2013. A pattern of pressure burst, high-coherence intervals, and diminishing-coherence intervals was observed for all takeoff and landing events without exception. The results of a phased microphone vs. linear infrasonic array comparison will be presented.

  9. A 128 pixel linear array for radiotherapy quality assurance

    NASA Astrophysics Data System (ADS)

    Franco, L.; Gómez, F.; Iglesias, A.; Lobato, R.; Marín, J.; Mosquera, J.; Pardo, J.; Pazos, A.; Pena, J.; Pombar, M.; Rodríguez, A.; Saavedra, D.; Sendón, J.; Yañez, A.

    2004-12-01

    New radiotherapy techniques require detectors able to verify and monitor the clinical beam with high spatial resolution and fast response. Room temperature organic liquid ionization detectors are becoming an alternative to standard air ionization chambers, due to their tissue equivalent behavior, their sensibility and small directional dependence. A liquid isooctane filled ionization linear array for radiotherapy quality assurance has been designed, built and tested. The detector consists of 128 pixels, each of them with an area of 1.7 mm×1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for high gradient beam profiles like those present in Intensity Modulated Radiation Therapy. The gap and the polarization voltage have been chosen in order to guarantee a linear relationship between the dose rate and the readout signal at high dose rates. As readout electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC.In the first device tests we have confirmed linearity up to a 6.7 Gy/min dose rate with a deviation less than 1%. A profile with a signal-to-noise ratio around 500 can be obtained for a 4 Gy/min dose rate with a 10 ms integration time.

  10. Thermal crosstalk simulation and measurement of linear terahertz detector arrays

    NASA Astrophysics Data System (ADS)

    Li, Weizhi; Huang, Zehua; Wang, Jun; Li, Mingyu; Gou, Jun; Jiang, Yadong

    2015-11-01

    Thermal simulation of differently structured linear terahertz detector arrays (TDAs) based on lithium tantalate was performed by finite element analysis (FEA). Simulation results revealed that a relatively simple TDA structure can have good thermal insulation, i.e., low thermal crosstalk effect (TCE), between adjacent pixels, which was thus selected for the real fabrication of TDA sample. Current responsivity (Ri) of the sample for a 2.52 THz source was measured to be 6.66 × 10-6 A/W and non-uniformity (NU) of Ri was 4.1%, showing good performance of the sample. TCE test result demonstrated that small TCE existed in the sample, which was in good agreement with the simulation results.

  11. Velocity magnitude estimation with linear arrays using Doppler bandwidth.

    PubMed

    Tortoli, P; Guidi, G; Mantovani, L; Newhouse, V L

    2001-04-01

    The dependence of pulsed wave Doppler bandwidth on parameters typical of linear transducer arrays used in commercial Duplex and color flow mapping systems is investigated experimentally. For a single flow line it is observed that this bandwidth generally depends not only on the scatterer velocity and the beam-to-flow angle, but also on the flow line range and orientation. This is due to the fact that in Duplex and color flow systems the transducer is differently focused in the scan and elevation planes and its aperture and focal lengths are often made to vary, depending on the distance of the flow line from the transducer. It is however experimentally demonstrated that, at points where the ultrasound beamwidths in the scan and elevation planes are both comparable to the sample volume length, the Doppler bandwidth is independent of the beam-to-flow angle. It is also shown that this invariance can be extended to other ranges by appropriately modifying the array aperture. Finally, as an application of this independence, the flow-line velocity magnitude in these beam regions is estimated with better than 5% uncertainty through a simple bandwidth measurement.

  12. Fast 2D DOA Estimation Algorithm by an Array Manifold Matching Method with Parallel Linear Arrays

    PubMed Central

    Yang, Lisheng; Liu, Sheng; Li, Dong; Jiang, Qingping; Cao, Hailin

    2016-01-01

    In this paper, the problem of two-dimensional (2D) direction-of-arrival (DOA) estimation with parallel linear arrays is addressed. Two array manifold matching (AMM) approaches, in this work, are developed for the incoherent and coherent signals, respectively. The proposed AMM methods estimate the azimuth angle only with the assumption that the elevation angles are known or estimated. The proposed methods are time efficient since they do not require eigenvalue decomposition (EVD) or peak searching. In addition, the complexity analysis shows the proposed AMM approaches have lower computational complexity than many current state-of-the-art algorithms. The estimated azimuth angles produced by the AMM approaches are automatically paired with the elevation angles. More importantly, for estimating the azimuth angles of coherent signals, the aperture loss issue is avoided since a decorrelation procedure is not required for the proposed AMM method. Numerical studies demonstrate the effectiveness of the proposed approaches. PMID:26907301

  13. A simplified solar cell array modelling program

    NASA Technical Reports Server (NTRS)

    Hughes, R. D.

    1982-01-01

    As part of the energy conversion/self sufficiency efforts of DSN engineering, it was necessary to have a simplified computer model of a solar photovoltaic (PV) system. This article describes the analysis and simplifications employed in the development of a PV cell array computer model. The analysis of the incident solar radiation, steady state cell temperature and the current-voltage characteristics of a cell array are discussed. A sample cell array was modelled and the results are presented.

  14. [Modeling and simulation of responses from ultrasonic linear phased array].

    PubMed

    He, Wenjing; Zhu, Yuanzhong; Wang, Yufeng; He, Lingli; Lai, Siyu

    2012-10-01

    Phased array transducers are very attractive because the beam generated by the arrays can be electronically focused and steered. The present work characterizes far-field 2D properties of phased array system by functions that are deduced from rectangle source, rectangle line array and phased array based on point source. Results are presented for the distribution of ultrasound intensity on plane xoz and on x-axis by simulation using numerical calculation. It is shown that the shape of response of rectangle line array is modulated by the single array element. It is also demonstrated that the delay time of phased array is the key to steer the beam, sacrificing the value of main lobe and increasing the number of side lobes.

  15. A digital sidelobe canceller for a linear phased-array

    NASA Astrophysics Data System (ADS)

    Wardrop, B.; Gould, D. M.

    The design and performance of a three auxiliary sidelobe canceller for use with a 25 element S-band phased-array is described. The phased-array incorporates a resistive-matrix multiple-beam former, and so the auxiliaries can be either elements of the array, or other beams. Experimental results showing its performance against multiple noise jammers are presented.

  16. Ultrasonic linear array validation via concrete test blocks

    NASA Astrophysics Data System (ADS)

    Hoegh, Kyle; Khazanovich, Lev; Ferraro, Chris; Clayton, Dwight

    2015-03-01

    Oak Ridge National Laboratory (ORNL) comparatively evaluated the ability of a number of NDE techniques to generate an image of the volume of 6.5' X 5.0' X 10″ concrete specimens fabricated at the Florida Department of Transportation (FDOT) NDE Validation Facility in Gainesville, Florida. These test blocks were fabricated to test the ability of various NDE methods to characterize various placements and sizes of rebar as well as simulated cracking and non-consolidation flaws. The first version of the ultrasonic linear array device, MIRA [version 1], was one of 7 different NDE equipment used to characterize the specimens. This paper deals with the ability of this equipment to determine subsurface characterizations such as reinforcing steel relative size, concrete thickness, irregularities, and inclusions using Kirchhoff-based migration techniques. The ability of individual synthetic aperture focusing technique (SAFT) B-scan cross sections resulting from self-contained scans are compared with various processing, analysis, and interpretation methods using the various features fabricated in the specimens for validation. The performance is detailed, especially with respect to the limitations and implications for evaluation of a thicker, more heavily reinforced concrete structures.

  17. Ultrasonic linear array validation via concrete test blocks

    SciTech Connect

    Hoegh, Kyle Khazanovich, Lev; Ferraro, Chris; Clayton, Dwight

    2015-03-31

    Oak Ridge National Laboratory (ORNL) comparatively evaluated the ability of a number of NDE techniques to generate an image of the volume of 6.5′ X 5.0′ X 10″ concrete specimens fabricated at the Florida Department of Transportation (FDOT) NDE Validation Facility in Gainesville, Florida. These test blocks were fabricated to test the ability of various NDE methods to characterize various placements and sizes of rebar as well as simulated cracking and non-consolidation flaws. The first version of the ultrasonic linear array device, MIRA [version 1], was one of 7 different NDE equipment used to characterize the specimens. This paper deals with the ability of this equipment to determine subsurface characterizations such as reinforcing steel relative size, concrete thickness, irregularities, and inclusions using Kirchhoff-based migration techniques. The ability of individual synthetic aperture focusing technique (SAFT) B-scan cross sections resulting from self-contained scans are compared with various processing, analysis, and interpretation methods using the various features fabricated in the specimens for validation. The performance is detailed, especially with respect to the limitations and implications for evaluation of a thicker, more heavily reinforced concrete structures.

  18. Synthesis arrangement and parity correction of linear array infrared detector

    NASA Astrophysics Data System (ADS)

    Wang, Qun; Hong, Pu; Wang, Bo; Wang, Chensheng

    2010-11-01

    According to the configuration and technical specification of the detector, which has multiple channels, channels mixing, high speed outputs and separate columns between odd and even, a real time digital processing unit based on the CPLD, FPGA and DSP has been developed to achieve the data synthesis and arrangement function and the parity correction algorithm. A special interface circuit with 4 CPLDs is designed to complete the first synthesis step where the 16 channels of data are combined into 4 channels. The second step is finished in FPGA and ROM address encoder where the 4 channels of data are combined into 1 channel. For output data synchronization, FIFO is adopted to achieve the delay of even channels in the parity correction. Data of odd channels enters the columns synthesis unit without any processing and even channels shall be processed in the columns synthesis unit after entering the FIFO unit first and experiencing the delay process. Thereby the pre-processing before image processing of the linear array thermal imager is accomplished.

  19. Acoustic trapping with a high frequency linear phased array.

    PubMed

    Zheng, Fan; Li, Ying; Hsu, Hsiu-Sheng; Liu, Changgeng; Tat Chiu, Chi; Lee, Changyang; Ham Kim, Hyung; Shung, K Kirk

    2012-11-19

    A high frequency ultrasonic phased array is shown to be capable of trapping and translating microparticles precisely and efficiently, made possible due to the fact that the acoustic beam produced by a phased array can be both focused and steered. Acoustic manipulation of microparticles by a phased array is advantageous over a single element transducer since there is no mechanical movement required for the array. Experimental results show that 45 μm diameter polystyrene microspheres can be easily and accurately trapped and moved to desired positions by a 64-element 26 MHz phased array.

  20. Acoustic trapping with a high frequency linear phased array

    PubMed Central

    Zheng, Fan; Li, Ying; Hsu, Hsiu-Sheng; Liu, Changgeng; Tat Chiu, Chi; Lee, Changyang; Ham Kim, Hyung; Shung, K. Kirk

    2012-01-01

    A high frequency ultrasonic phased array is shown to be capable of trapping and translating microparticles precisely and efficiently, made possible due to the fact that the acoustic beam produced by a phased array can be both focused and steered. Acoustic manipulation of microparticles by a phased array is advantageous over a single element transducer since there is no mechanical movement required for the array. Experimental results show that 45 μm diameter polystyrene microspheres can be easily and accurately trapped and moved to desired positions by a 64-element 26 MHz phased array. PMID:23258939

  1. Breadboard linear array scan imager using LSI solid-state technology

    NASA Technical Reports Server (NTRS)

    Tracy, R. A.; Brennan, J. A.; Frankel, D. G.; Noll, R. E.

    1976-01-01

    The performance of large scale integration photodiode arrays in a linear array scan (pushbroom) breadboard was evaluated for application to multispectral remote sensing of the earth's resources. The technical approach, implementation, and test results of the program are described. Several self scanned linear array visible photodetector focal plane arrays were fabricated and evaluated in an optical bench configuration. A 1728-detector array operating in four bands (0.5 - 1.1 micrometer) was evaluated for noise, spectral response, dynamic range, crosstalk, MTF, noise equivalent irradiance, linearity, and image quality. Other results include image artifact data, temporal characteristics, radiometric accuracy, calibration experience, chip alignment, and array fabrication experience. Special studies and experimentation were included in long array fabrication and real-time image processing for low-cost ground stations, including the use of computer image processing. High quality images were produced and all objectives of the program were attained.

  2. Modulation Transfer Function (MTF) measurement techniques for lenses and linear detector arrays

    NASA Technical Reports Server (NTRS)

    Schnabel, J. J., Jr.; Kaishoven, J. E., Jr.; Tom, D.

    1984-01-01

    Application is the determination of the Modulation Transfer Function (MTF) for linear detector arrays. A system set up requires knowledge of the MTF of the imaging lens. Procedure for this measurement is described for standard optical lab equipment. Given this information, various possible approaches to MTF measurement for linear arrays is described. The knife edge method is then described in detail.

  3. A self-cohering technique for linear arrays using the Phase Gradient Autofocus Algorithm

    SciTech Connect

    Wahl, D.E.

    1991-02-01

    A towed linear hydrophone array is subject to snakelike bending. If the array were processed as if it were truly linear, poor array gain coupled with a degraded source bearing estimate would result. The signal phase errors produced by sensor position uncertainty in passive sonar arrays are similar to those observed in Synthetic Aperture Radar (SAR) imagery. The Phase Gradient Autofocus (PGA) Algorithm has been shown to be a robust and effective method used to extract degrading phase errors prevalent in SAR imagery. This report shows that with slight modifications, the PGA algorithm can be applied to correct phase errors resulting from sensor position uncertainty introduced into linear-passive arrays. The results of the technique applied to simulated linear array data is also presented. 9 refs., 8 figs.

  4. Parallel Spectral Acquisition with an ICR Cell Array

    PubMed Central

    Park, Sung-Gun; Anderson, Gordon A.; Navare, Arti T.; Bruce, James E.

    2016-01-01

    Mass measurement accuracy is a critical analytical figure-of-merit in most areas of mass spectrometry application. However, the time required for acquisition of high resolution, high mass accuracy data limits many applications and is an aspect under continual pressure for development. Current efforts target implementation of higher electrostatic and magnetic fields because ion oscillatory frequencies increase linearly with field strength. As such, the time required for spectral acquisition of a given resolving power and mass accuracy decreases linearly with increasing fields. Mass spectrometer developments to include multiple high resolution detectors that can be operated in parallel could further decrease the acquisition time by a factor of n, the number of detectors. Efforts described here resulted in development of an instrument with a set of Fourier transform ion cyclotron resonance (ICR) cells as detectors that constitute the first MS array capable of parallel high resolution spectral acquisition. ICR cell array systems consisting of three or five cells were constructed with printed circuit boards and installed within a single superconducting magnet and vacuum system. Independent ion populations were injected and trapped within each cell in the array. Upon filling the array, all ions in all cells were simultaneously excited and ICR signals from each cell were independently amplified and recorded in parallel. Presented here are the initial results of successful parallel spectral acquisition, parallel MS and MS/MS measurements, and parallel high resolution acquisition with the MS array system. PMID:26669509

  5. Parallel Spectral Acquisition with an Ion Cyclotron Resonance Cell Array.

    PubMed

    Park, Sung-Gun; Anderson, Gordon A; Navare, Arti T; Bruce, James E

    2016-01-19

    Mass measurement accuracy is a critical analytical figure-of-merit in most areas of mass spectrometry application. However, the time required for acquisition of high-resolution, high mass accuracy data limits many applications and is an aspect under continual pressure for development. Current efforts target implementation of higher electrostatic and magnetic fields because ion oscillatory frequencies increase linearly with field strength. As such, the time required for spectral acquisition of a given resolving power and mass accuracy decreases linearly with increasing fields. Mass spectrometer developments to include multiple high-resolution detectors that can be operated in parallel could further decrease the acquisition time by a factor of n, the number of detectors. Efforts described here resulted in development of an instrument with a set of Fourier transform ion cyclotron resonance (ICR) cells as detectors that constitute the first MS array capable of parallel high-resolution spectral acquisition. ICR cell array systems consisting of three or five cells were constructed with printed circuit boards and installed within a single superconducting magnet and vacuum system. Independent ion populations were injected and trapped within each cell in the array. Upon filling the array, all ions in all cells were simultaneously excited and ICR signals from each cell were independently amplified and recorded in parallel. Presented here are the initial results of successful parallel spectral acquisition, parallel mass spectrometry (MS) and MS/MS measurements, and parallel high-resolution acquisition with the MS array system.

  6. Performance of the linear array HPV genotyping test on paired cytological and formalin-fixed, paraffin-embedded cervical samples.

    PubMed

    Donà, Maria Gabriella; Ronchetti, Livia; Giuliani, Massimo; Carosi, Mariantonia; Rollo, Francesca; Congiu, Mario; Mazza, Domenica; Pescarmona, Edoardo; Vocaturo, Amina; Benevolo, Maria

    2013-05-01

    Detection and genotyping of human papillomavirus (HPV) from formalin-fixed, paraffin-embedded (FFPE) samples may be difficult when using assays based on amplification of large fragments. The objective of the present study was to investigate the performance of the Linear Array HPV Genotyping Test (Linear Array) on FFPE cervical cone biopsy specimens using paired cytologic samples obtained immediately before the conization as a criterion standard. Thirty-nine samples of grade 2 or higher cervical intraepithelial neoplasia were selected; all of the corresponding cytological samples were positive by the Linear Array and had a report of atypical squamous cells of undetermined significance or worse. A valid Linear Array test result was obtained for 38 FFPE specimens (97.4%, 95% CI 88.0 to 99.9). Specifically, 34 were HPV-positive (89.5%, 95% CI 76.5 to 96.9) and 4 were HPV-negative (10.5%, 95% CI 3.4 to 23.5). The overall agreement of the results obtained for the cytologic and histologic paired samples was good (Cohen's κ = 0.85, SE = 0.082, P = 0.000). Further analysis of samples with negative or invalid Linear Array test results, both modifying the nucleic acids extraction protocol and using the INNO-LiPA assay, suggested that failure of the Linear Array test in HPV detection from tissues was probably due to DNA fragmentation. Parallel analysis of paired FFPE and cytologic samples is extremely useful for evaluation of the efficiency of PCR-based assays in HPV detection and genotyping from tissue samples. In the present study, false-negative results were obtained in a limited percentage of cases, our data depicting the successful performance of the Linear Array test on FFPE samples.

  7. Optimal piecewise linear schedules for LSGP- and LPGS-decomposed array processors via quadratic programming

    NASA Astrophysics Data System (ADS)

    Zimmermann, Karl-Heinz; Achtziger, Wolfgang

    2001-09-01

    The size of a systolic array synthesized from a uniform recurrence equation, whose computations are mapped by a linear function to the processors, matches the problem size. In practice, however, there exist several limiting factors on the array size. There are two dual schemes available to derive arrays of smaller size from large-size systolic arrays based on the partitioning of the large-size arrays into subarrays. In LSGP, the subarrays are clustered one-to-one into the processors of a small-size array, while in LPGS, the subarrays are serially assigned to a reduced-size array. In this paper, we propose a common methodology for both LSGP and LPGS based on polyhedral partitionings of large-size k-dimensional systolic arrays which are synthesized from n-dimensional uniform recurrences by linear mappings for allocation and timing. In particular, we address the optimization problem of finding optimal piecewise linear timing functions for small-size arrays. These are mappings composed of linear timing functions for the computations of the subarrays. We study a continuous approximation of this problem by passing from piecewise linear to piecewise quasi-linear timing functions. The resultant problem formulation is then a quadratic programming problem which can be solved by standard algorithms for nonlinear optimization problems.

  8. Linear scanning array with bulk ferroelectric-integrated feed network.

    PubMed

    Teo, Peng-Thian; Jose, Kollakompil A; Wang, Ya-Jun; Lee, Ching-Kwang; Varadan, Vijay K

    2002-05-01

    Variable ferroelectric delay line technology has been utilized to implement a proof-of-concept, continuous scanning, ferroelectric integrated phased array antenna system. S21 phase shifts of up to 157 degrees have been achieved from the phase shifter itself via analogous variation of a DC bias. When integrated into a phased array, beam scanning of at least +/-12 degrees is achieved prior to any optimization. Some of the key material requirements, fabrication procedures, characterization, and assembly of the ferroelectric material will be revealed. The design, integration, and performance of the array system using such phased shifters will be presented.

  9. Comparison of Hybrid Capture II, Linear Array, and a Bead-Based Multiplex Genotyping Assay for Detection of Human Papillomavirus in Women with Negative Pap Test Results and Atypical Squamous Cells of Undetermined Significance

    PubMed Central

    Comar, Manola; Iannacone, Michelle R.; Casalicchio, Giorgia; McKay-Chopin, Sandrine; Tommasino, Massimo

    2012-01-01

    Many methods with different levels of analytical sensitivity and clinical specificity have been developed to detect the presence of high-risk (HR) types of the human papillomavirus (HPV) in cervical samples. The Hybrid Capture II (HC-II) assay is broadly used for primary screening. In addition, several HPV genotyping assays, based on PCR methods, display higher sensitivity than the HC-II and are also used in screening programs. We evaluated the performance of three HPV DNA tests, namely, the HC-II, the Linear Array (LA) HPV genotyping assay, and an HPV type-specific E7 PCR bead-based multiplex genotyping assay (TS-MPG) that is a laboratory-developed method for the detection of HPV, in 94 women with atypical squamous cells of undetermined significance (ASC-US) and in cytological samples from 86 women with a negative Pap test. The HPV prevalence with the TS-MPG assay was increased compared to the prevalence with the LA and HC-II assays. The HPV DNA prevalence in women with ASC-US was greater with the TS-MPG assay (46.2%) than with the LA (36.3%) and HC-II (29.7%) assays. The HPV DNA prevalence in the control group was greater with the TS-MPG assay (32.1%) than with the LA assay (10.7%). Two women with ASC-US who were HPV DNA negative by the HC-II and positive by the TS-MPG or/and LA assays had lesions that progressed to low-grade squamous intraepithelial and high-grade squamous intraepithelial lesions. This study shows that the TS-MPG assay exhibited higher analytical sensitivity than the LA and HC-II assays for the detection of HPV DNA, which reduces the potential to incorrectly identify a woman's HPV infection status. PMID:23035194

  10. Linear and Planar Array Formation in Wireless Sensor Networks

    DTIC Science & Technology

    2007-06-01

    RELATED WORK A beamforming approach for distributed wireless sensor networks introduced by Vincent et al. [1] assembles a subset of sensor nodes into a...This work investigated the formation of arrays of nodes in a randomly deployed sensor field with the main objective of evaluating different approaches...nodes were added to the array. B. FUTURE WORK It was assumed in this work that the nodes in the sensor field have only knowledge of their

  11. Real-time assessment of a linear pyroelectric sensor array for object classication

    NASA Astrophysics Data System (ADS)

    White, William E., III; Brown, Jeremy B.; Chari, Srikant; Jacobs, Eddie L.

    2010-10-01

    Pyroelectric linear arrays can be used to generate profiles of targets. Simulations have shown that generated profiles can be used to classify human and animal targets. A pyroelectric array system was used to collect data and classify targets as either human or non-human in real time. The pyroelectric array system consists of a 128-element Dias 128LTI pyroelectric linear array, an F/0.86 germanium lens, and an 18F4550 pic microcontroller for A/D conversion and communication. The classifier used for object recognition was trained using data collected in petting zoos and tested using data collected at the US-Mexico border in Arizona.

  12. Method of fabricating a solar cell array

    NASA Technical Reports Server (NTRS)

    Lazzery, Angelo G. (Inventor); Crouthamel, Marvin S. (Inventor); Coyle, Peter J. (Inventor)

    1982-01-01

    A first set of pre-tabbed solar cells are assembled in a predetermined array with at least part of each tab facing upward, each tab being fixed to a bonding pad on one cell and abutting a bonding pad on an adjacent cell. The cells are held in place with a first vacuum support. The array is then inverted onto a second vacuum support which holds the tabs firmly against the cell pads they abut. The cells are exposed to radiation to melt and reflow the solder pads for bonding the tab portions not already fixed to bonding pads to these pads.

  13. Sorting white blood cells in microfabricated arrays

    NASA Astrophysics Data System (ADS)

    Castelino, Judith Andrea Rose

    Fractionating white cells in microfabricated arrays presents the potential for detecting cells with abnormal adhesive or deformation properties. A possible application is separating nucleated fetal red blood cells from maternal blood. Since fetal cells are nucleated, it is possible to extract genetic information about the fetus from them. Separating fetal cells from maternal blood would provide a low cost noninvasive prenatal diagnosis for genetic defects, which is not currently available. We present results showing that fetal cells penetrate further into our microfabricated arrays than adult cells, and that it is possible to enrich the fetal cell fraction using the arrays. We discuss modifications to the array which would result in further enrichment. Fetal cells are less adhesive and more deformable than adult white cells. To determine which properties limit penetration, we compared the penetration of granulocytes and lymphocytes in arrays with different etch depths, constriction size, constriction frequency, and with different amounts of metabolic activity. The penetration of lymphocytes and granulocytes into constrained and unconstrained arrays differed qualitatively. In constrained arrays, the cells were activated by repeated shearing, and the number of cells stuck as a function of distance fell superexponentially. In unconstrained arrays the number of cells stuck fell slower than an exponential. We attribute this result to different subpopulations of cells with different sticking parameters. We determined that penetration in unconstrained arrays was limited by metabolic processes, and that when metabolic activity was reduced penetration was limited by deformability. Fetal cells also contain a different form of hemoglobin with a higher oxygen affinity than adult hemoglobin. Deoxygenated cells are paramagnetic and are attracted to high magnetic field gradients. We describe a device which can separate cells using 10 μm magnetic wires to deflect the paramagnetic

  14. Feasibility of a linear phased acoustic array for health monitoring of gears

    NASA Astrophysics Data System (ADS)

    Hood, Adrian A.; Pines, Darryll J.

    2001-08-01

    This paper investigates the feasibility of sensing damage emanating from rotating drivetrain elements such as bearings, gear teeth, and drive shafts via airborne paths. A linear phased acoustic array of microphones is evaluated as a potential fault detection scheme for detecting acoustic signatures radiating from gearbox components. Specifically, this paper discusses the minimum spot size for a given linear array geometry and its sensitivity to acoustic sources. In addition, the use of beam focusing and beam steering to track individual tooth mesh dynamics are analyzed. Experimental results for a linear array are presented to illustrate the concepts of adaptive beam steering and acoustic filtering. This feasibility study indicates that the linear array can be used to track the acoustic signatures of gear mesh dynamics at higher harmonics of the mesh frequency.

  15. Geometrical Transformation of Linear Diode-Laser Arrays for Longitudinal Pumping of Solid-State Lasers

    DTIC Science & Technology

    1992-05-26

    of Nd:YAG crystal vs incident power from the geometrically transformed laser - diode array. 24 12 TEM00 output power from Nd:YAG laser when pumped by n...MASSACHUSETTS INSTITUTE OF TECHNOLOGY LINCOLN LABORATORY GEOMETRICAL TRANSFORMATION OF LINEAR DIODE - LASER ARRAYS FOR LONGITUDINAL PUMPING OF SOLID-STATE...Photograph of pump spot at the lens focal plane. 22 10 Curvature of the laser - diode array emitting facet. 23 11 TEMOO output power from 1.06 pm transition

  16. Compression dynamics of quasi-spherical wire arrays with different linear mass profiles

    SciTech Connect

    Mitrofanov, K. N. Aleksandrov, V. V.; Gritsuk, A. N.; Grabovski, E. V.; Frolov, I. N.; Laukhin, Ya. N.; Oleinik, G. M.; Ol’khovskaya, O. G.

    2016-09-15

    Results of experimental studies of the implosion of quasi-spherical wire (or metalized fiber) arrays are presented. The goal of the experiments was to achieve synchronous three-dimensional compression of the plasma produced in different regions of a quasi-spherical array into its geometrical center. To search for optimal synchronization conditions, quasi-spherical arrays with different initial profiles of the linear mass were used. The following dependences of the linear mass on the poloidal angle were used: m{sub l}(θ) ∝ sin{sup –1}θ and m{sub l}(θ) ∝ sin{sup –2}θ. The compression dynamics of such arrays was compared with that of quasi-spherical arrays without linear mass profiling, m{sub l}(θ) = const. To verify the experimental data, the spatiotemporal dynamics of plasma compression in quasi-spherical arrays was studied using various diagnostics. The experiments on three-dimensional implosion of quasi-spherical arrays made it possible to study how the frozen-in magnetic field of the discharge current penetrates into the array. By measuring the magnetic field in the plasma of a quasi-spherical array, information is obtained on the processes of plasma production and formation of plasma flows from the wire/fiber regions with and without an additionally deposited mass. It is found that penetration of the magnetic flux depends on the initial linear mass profile m{sub l}(θ) of the quasi-spherical array. From space-resolved spectral measurements and frame imaging of plasma X-ray emission, information is obtained on the dimensions and shape of the X-ray source formed during the implosion of a quasi-spherical array. The intensity of this source is estimated and compared with that of the Z-pinch formed during the implosion of a cylindrical array.

  17. Scattering of linear and nonlinear waves in a waveguide array with a PT-symmetric defect

    SciTech Connect

    Dmitriev, Sergey V.; Suchkov, Sergey V.; Sukhorukov, Andrey A.; Kivshar, Yuri S.

    2011-07-15

    We study the scattering of linear and nonlinear waves in a long waveguide array with a parity-time (PT)-symmetric defect created by two waveguides with balanced gain and loss. We present exact solutions for the scattering of linear waves on such a defect, and then demonstrate numerically that the linear theory can describe, with a good accuracy, the soliton scattering in the case of weak nonlinearity. We reveal that the reflected and transmitted linear and nonlinear waves can be amplified substantially after interaction with the PT-symmetric defect thus allowing an active control of the wave scattering in the array.

  18. Comparison of Linear Array and Line Blot Assay for Detection of Human Papillomavirus and Diagnosis of Cervical Precancer and Cancer in the Atypical Squamous Cell of Undetermined Significance and Low-Grade Squamous Intraepithelial Lesion Triage Study▿

    PubMed Central

    Castle, Philip E.; Gravitt, Patti E.; Solomon, Diane; Wheeler, Cosette M.; Schiffman, Mark

    2008-01-01

    We evaluated Linear Array (LA), a newly commercialized PGMY09/11 L1 consensus primer PCR test that detects 37 human papillomavirus (HPV) genotypes by reverse line blot hybridization, for the detection of individual HPV genotypes and carcinogenic HPV and its clinical performance for detecting 2-year cumulative cervical precancer and cancer using archived specimens from the Atypical Squamous Cell of Undetermined Significance (ASCUS) and Low-Grade Squamous Intraepithelial Lesion Triage Study. LA testing was conducted on enrollment specimens from women referred because of an ASCUS Pap test. To gauge the performance of the new test, the results were compared to those of its prototype predecessor assay, Line Blot Assay (LBA), restricted to paired results (n = 3,335). LA testing was done masked to LBA results and clinical outcomes. The results of LA and LBA testing were compared for detection of carcinogenic HPV and clinical outcomes of cervical precancer and cancer. Overall, 50% and 55% of the women tested positive for carcinogenic HPV by LBA and LA, respectively (P < 0.0001). The percent agreement for carcinogenic HPV detection was 88%, percent positive agreement was 80%, and kappa was 0.76 for detection of carcinogenic HPV by the two assays. There was a significant increase in detection by LA for most of the 37 HPV genotypes targeted by both assays, including for 13 of 14 carcinogenic HPV genotypes. LA detected more multiple-genotype infections for all HPV genotypes among HPV-positive women (P < 0.0001) and for carcinogenic HPV genotypes among carcinogenic-HPV-positive women (P < 0.0001). LA was more sensitive (92.3% versus 87.1%; P = 0.003) and less specific (48.2% versus 54.0%; P < 0.0001) than LBA for 2-year cumulative cervical precancer and cancer as diagnosed by the Pathology Quality Control Group. In conclusion, we found LA to be a promising assay for the detection of HPV genotypes and carcinogenic HPV, and it may be clinically useful for the detection of

  19. Comparison of linear array and line blot assay for detection of human papillomavirus and diagnosis of cervical precancer and cancer in the atypical squamous cell of undetermined significance and low-grade squamous intraepithelial lesion triage study.

    PubMed

    Castle, Philip E; Gravitt, Patti E; Solomon, Diane; Wheeler, Cosette M; Schiffman, Mark

    2008-01-01

    We evaluated Linear Array (LA), a newly commercialized PGMY09/11 L1 consensus primer PCR test that detects 37 human papillomavirus (HPV) genotypes by reverse line blot hybridization, for the detection of individual HPV genotypes and carcinogenic HPV and its clinical performance for detecting 2-year cumulative cervical precancer and cancer using archived specimens from the Atypical Squamous Cell of Undetermined Significance (ASCUS) and Low-Grade Squamous Intraepithelial Lesion Triage Study. LA testing was conducted on enrollment specimens from women referred because of an ASCUS Pap test. To gauge the performance of the new test, the results were compared to those of its prototype predecessor assay, Line Blot Assay (LBA), restricted to paired results (n = 3,335). LA testing was done masked to LBA results and clinical outcomes. The results of LA and LBA testing were compared for detection of carcinogenic HPV and clinical outcomes of cervical precancer and cancer. Overall, 50% and 55% of the women tested positive for carcinogenic HPV by LBA and LA, respectively (P < 0.0001). The percent agreement for carcinogenic HPV detection was 88%, percent positive agreement was 80%, and kappa was 0.76 for detection of carcinogenic HPV by the two assays. There was a significant increase in detection by LA for most of the 37 HPV genotypes targeted by both assays, including for 13 of 14 carcinogenic HPV genotypes. LA detected more multiple-genotype infections for all HPV genotypes among HPV-positive women (P < 0.0001) and for carcinogenic HPV genotypes among carcinogenic-HPV-positive women (P < 0.0001). LA was more sensitive (92.3% versus 87.1%; P = 0.003) and less specific (48.2% versus 54.0%; P < 0.0001) than LBA for 2-year cumulative cervical precancer and cancer as diagnosed by the Pathology Quality Control Group. In conclusion, we found LA to be a promising assay for the detection of HPV genotypes and carcinogenic HPV, and it may be clinically useful for the detection of

  20. Characterization of the system functions of ultrasonic linear phased array inspection systems.

    PubMed

    Huang, Ruiju; Schmerr, Lester W

    2009-02-01

    This work characterizes the electrical and electromechanical aspects of an ultrasonic linear phased array inspection system, using a matrix of system functions that are obtained from the measured response of individual array elements in a simple reference experiment. It is shown that for the arrays tested all these system functions are essentially identical, allowing one to use a single system function to characterize the entire array, as done for an ordinary single element transducer. The variation of this single system function with the number of elements firing in the array or with changes of the delay law used is examined. It is also demonstrated that once such a single system function is obtained for an array, it can be used in a complete ultrasonic measurement model to accurately predict the array response measured from a reference reflector in an immersion setup.

  1. Si Wire-Array Solar Cells

    NASA Astrophysics Data System (ADS)

    Boettcher, Shannon

    2010-03-01

    Micron-scale Si wire arrays are three-dimensional photovoltaic absorbers that enable orthogonalization of light absorption and carrier collection and hence allow for the utilization of relatively impure Si in efficient solar cell designs. The wire arrays are grown by a vapor-liquid-solid-catalyzed process on a crystalline (111) Si wafer lithographically patterned with an array of metal catalyst particles. Following growth, such arrays can be embedded in polymethyldisiloxane (PDMS) and then peeled from the template growth substrate. The result is an unusual photovoltaic material: a flexible, bendable, wafer-thickness crystalline Si absorber. In this paper I will describe: 1. the growth of high-quality Si wires with controllable doping and the evaluation of their photovoltaic energy-conversion performance using a test electrolyte that forms a rectifying conformal semiconductor-liquid contact 2. the observation of enhanced absorption in wire arrays exceeding the conventional light trapping limits for planar Si cells of equivalent material thickness and 3. single-wire and large-area solid-state Si wire-array solar cell results obtained to date with directions for future cell designs based on optical and device physics. In collaboration with Michael Kelzenberg, Morgan Putnam, Joshua Spurgeon, Daniel Turner-Evans, Emily Warren, Nathan Lewis, and Harry Atwater, California Institute of Technology.

  2. Assembling solar-cell arrays

    NASA Technical Reports Server (NTRS)

    Bloch, J. T.; Hanger, R. T.; Nichols, F. W.

    1979-01-01

    Modified 70 mm movie film editor automatically attaches solar cells to flexible film substrate. Machine can rapidly and inexpensively assemble cells for solar panels at rate of 250 cells per minute. Further development is expected to boost production rate to 1000 cells per minute.

  3. Micro-Machined High-Frequency (80 MHz) PZT Thick Film Linear Arrays

    PubMed Central

    Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K. Kirk

    2010-01-01

    This paper presents the development of a micro-machined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT solgel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (−6 dB) of 60%. An insertion loss of −41 dB and adjacent element crosstalk of −21 dB were found at the center frequency. PMID:20889407

  4. A parametric study of ultrasonic beam profiles for a linear phased array transducer.

    PubMed

    Lee, J H; Choi, S W

    2000-01-01

    A numerical simulation model is presented to investigate the influences of design parameters of linear phased array transducers on beam focusing and steering performance. The characteristic of ultrasonic beam profiles has been simulated on the basis of the Huygen's superposition principle. For the simulation, a linear phased array is considered as the composition of finite number of elements separated by equidistance. Individual elements are considered as two-dimensional point sources. The waves generated from piezoelectric elements are considered as simplified transient ultrasonic waves that are constructed with the cosine function enveloped with a Hanning window. The characteristic of ultrasonic wave propagation into a medium from the phased array transducer is described. The effects of the number, the interelement spacing, steering angle, the focal length, and frequency bandwidth of the piezoelectric elements on beam directivity and ultrasonic pressure field in a linear phased array transducer are systematically discussed.

  5. Linearized superconducting quantum interference device array for high bandwidth frequency-domain readout multiplexing.

    PubMed

    Lanting, T; Dobbs, M; Spieler, H; Lee, A T; Yamamoto, Y

    2009-09-01

    We have designed and demonstrated a superconducting quantum interference device (SQUID) array linearized with cryogenic feedback. To achieve the necessary loop gain, a 300-element series array SQUID is constructed from three monolithic 100-element series arrays. A feedback resistor completes the loop from the SQUID output to the input coil. The short feedback path of this linearized SQUID array (LISA) allows for a substantially larger flux-locked loop bandwidth as compared to a SQUID flux-locked loop that includes a room temperature amplifier. The bandwidth, linearity, noise performance, and 3 Phi(0) dynamic range of the LISA are sufficient for its use in our target application: the multiplexed readout of transition-edge sensor bolometers.

  6. Fabrication, measurement, and alignment uniformity analysis of linear arrays of optical fibers

    SciTech Connect

    Klingsporn, P.E.

    1997-06-01

    Techniques were developed for assembling a linear array of optical fibers between two silicon plates and polishing the fiber ends in a plane perpendicular to the fiber axis. The silicon plates contained etched V-grooves for capturing the fibers. Optical fibers from two sources were evaluated, along with silicon plates supplied by two sources. Most of the arrays were assembled by epoxy bonding, but some effort was made to form a eutectic bond using gold metallized fibers with gold-coated silicon plates. Measurements were made of the uniformity of spacing of the fiber mode field centers in the linear array. The work was performed to develop a multi-fiber linear array connector to couple optical signals to and from optoelectronic devices.

  7. Digital cell counting device integrated with a single-cell array.

    PubMed

    Saeki, Tatsuya; Hosokawa, Masahito; Lim, Tae-kyu; Harada, Manabu; Matsunaga, Tadashi; Tanaka, Tsuyoshi

    2014-01-01

    In this paper, we present a novel cell counting method accomplished using a single-cell array fabricated on an image sensor, complementary metal oxide semiconductor sensor. The single-cell array was constructed using a microcavity array, which can trap up to 7,500 single cells on microcavities periodically arranged on a plane metallic substrate via the application of a negative pressure. The proposed method for cell counting is based on shadow imaging, which uses a light diffraction pattern generated by the microcavity array and trapped cells. Under illumination, the cell-occupied microcavities are visualized as shadow patterns in an image recorded by the complementary metal oxide semiconductor sensor due to light attenuation. The cell count is determined by enumerating the uniform shadow patterns created from one-on-one relationships with single cells trapped on the microcavities in digital format. In the experiment, all cell counting processes including entrapment of non-labeled HeLa cells from suspensions on the array and image acquisition of a wide-field-of-view of 30 mm(2) in 1/60 seconds were implemented in a single integrated device. As a result, the results from the digital cell counting had a linear relationship with those obtained from microscopic observation (r(2)  = 0.99). This platform could be used at extremely low cell concentrations, i.e., 25-15,000 cells/mL. Our proposed system provides a simple and rapid miniaturized cell counting device for routine laboratory use.

  8. A 400 KHz line rate 2048-pixel stitched SWIR linear array

    NASA Astrophysics Data System (ADS)

    Anchlia, Ankur; Vinella, Rosa M.; Gielen, Daphne; Wouters, Kristof; Vervenne, Vincent; Hooylaerts, Peter; Deroo, Pieter; Ruythooren, Wouter; De Gaspari, Danny; Das, Jo; Merken, Patrick

    2016-05-01

    Xenics has developed a family of stitched SWIR long linear arrays that operate up to 400 KHz of line rate. These arrays serve medical and industrial applications that require high line rates as well as space applications that require long linear arrays. The arrays are based on a modular ROIC design concept: modules of 512 pixels are stitched during fabrication to achieve 512, 1024 and 2048 pixel arrays. Each 512-pixel module has its own on-chip digital sequencer, analog readout chain and 4 output buffers. This modular concept enables a long array to run at a high line rates irrespective of the array length, which limits the line rate in a traditional linear array. The ROIC is flip-chipped with InGaAs detector arrays. The FPA has a pixel pitch of 12.5μm and has two pixel flavors: square (12.5μm) and rectangular (250μm). The frontend circuit is based on Capacitive Trans-impedance Amplifier (CTIA) to attain stable detector bias, and good linearity and signal integrity, especially at high speeds. The CTIA has an input auto-zero mechanism that allows to have low detector bias (<20mV). An on-chip Correlated Double Sample (CDS) facilitates removal of CTIA KTC and 1/f noise, and other offsets, achieving low noise performance. There are five gain modes in the FPA giving the full well range from 85Ke- to 40Me-. The measured input referred noise is 35e-rms in the highest gain mode. The FPA operates in Integrate While Read mode and, at a master clock rate of 60MHz and a minimum integration time of 1.4μs, achieves the highest line rate of 400 KHz. In this paper, design details and measurements results are presented in order to demonstrate the array performance.

  9. Detection Performance of Horizontal Linear Hydrophone Arrays in Shallow Water.

    DTIC Science & Technology

    1980-12-15

    computer time). On the other hand this property [Eq. 3] causes the covariance matrices to be Toeplitz matrices, which are completely descrihed by their...energy minimum by split-beam tecnnique is misleading for directions other than broadside. b. The unsymmetrical spread is a property of the linear...almost independent of the channel parameters ( soun ?-, peed profile, depth of water, source, receiver, frequency). b. As the matrix matched filter H

  10. Imaging of pancreas divisum by linear-array endoscopic ultrasonography

    PubMed Central

    Sharma, Malay; Pathak, Amit; Rameshbabu, Chittapuram Srinivasan; Rai, Praveer; Kirnake, Vijendra; Shoukat, Abid

    2016-01-01

    Pancreas divisum (PD) is the most common developmental anatomic variant of pancreatic duct. Endoscopic ultrasound (EUS) is often performed to evaluate idiopathic pancreatitis and has been shown to have high accuracy in diagnosis of PD. The different techniques to identify PD by linear EUS have been described differently by different authors. If EUS is done with a proper technique it can be a valuable tool in the diagnosis of PD. The anatomical and technical background of different signs has not been described so far. This article summarizes the different techniques of imaging of pancreatic duct in a suspected case of PD and gives a technical explanation of various signs. The common signs seen during evaluation of pancreatic duct in PD are stack sign of linear EUS, crossed duct sign on linear EUS, the dominant duct and ventral dorsal duct (VD) transition. Few other signs are described which include duct above duct, short ventral duct /absent ventral duct, separate opening of ducts with no communication, separate opening of ducts with filamentous communication, stacking of duct of Santorini and indirect signs like santorinecele. The principles of the sign have been explained on an anatomical basis and the techniques and the principles described in the review will be helpful in technical evaluation of PD during EUS. PMID:26879163

  11. Time-resolved step-scan infrared imaging system utilizing a linear array detector.

    PubMed

    Sugiyama, Hiroshi; Koshoubu, Jun; Kashiwabara, Seiichi; Nagoshi, Toshiyuki; Larsen, Richard A; Akao, Kenichi

    2008-01-01

    A time-resolved infrared (IR) imaging system combined with a multichannel IR microscope, which utilizes a 16 channel linear array (LA) detector, and step-scan Fourier transform infrared (FT-IR) microscope was developed. The LA detector integrates a readout circuit on each detector element, so the detected signals can be read simultaneously. Thus, this system can perform high speed imaging using the step-scan method, similar to a single channel detector. To verify the capabilities of this system, a reflective sample was examined whose position was altered using a piezo actuator activated by an alternating voltage. In addition, the localization of relaxation dynamics for the liquid crystal (LC) molecules in an LC cell under oscillating electric field conditions was detected by this system.

  12. Low cost solar cell arrays

    NASA Technical Reports Server (NTRS)

    Iles, P. A.; Mclennan, H.

    1975-01-01

    Limitations in both space and terrestial markets for solar cells are described. Based on knowledge of the state-of-the-art, six cell options are discussed; as a result of this discussion, the three most promising options (involving high, medium and low efficiency cells respectively) were selected and analyzed for their probable costs. The results showed that all three cell options gave promise of costs below $10 per watt in the near future. Before further cost reductions can be achieved, more R and D work is required; suggestions for suitable programs are given.

  13. Fast Ultrasound Beam Prediction for Linear and Regular Two-dimensional Arrays

    PubMed Central

    Hlawitschka, Mario; McGough, Robert J.; Ferrara, Katherine W.; Kruse, Dustin E.

    2012-01-01

    Real-time beam predictions are highly desirable for the patient-specific computations required in ultrasound therapy guidance and treatment planning. To address the long-standing issue of the computational burden associated with calculating the acoustic field in large volumes, we use graphics processing unit (GPU) computing to accelerate the computation of monochromatic pressure fields for therapeutic ultrasound arrays. In our strategy, we start with acceleration of field computations for single rectangular pistons, and then we explore fast calculations for arrays of rectangular pistons. For single-piston calculations, we employ the fast near-field method (FNM) to accurately and efficiently estimate the complex near-field wave patterns for rectangular pistons in homogeneous media. The FNM is compared with the Rayleigh-Sommerfeld method (RSM) for the number of abscissas required in the respective numerical integrations to achieve 1%, 0.1%, and 0.01% accuracy in the field calculations. Next, algorithms are described for accelerated computation of beam patterns for two different ultrasound transducer arrays: regular 1-D linear arrays and regular 2-D linear arrays. For the array types considered, the algorithm is split into two parts: 1) the computation of the field from one piston, and 2) the computation of a piston-array beam pattern based on a pre-computed field from one piston. It is shown that the process of calculating an array beam pattern is equivalent to the convolution of the single-piston field with the complex weights associated with an array of pistons. Our results show that the algorithms for computing monochromatic fields from linear and regularly spaced arrays can benefit greatly from GPU computing hardware, exceeding the performance of an expensive CPU by more than 100 times using an inexpensive GPU board. For a single rectangular piston, the FNM method facilitates volumetric computations with 0.01% accuracy at rates better than 30 ns per field point

  14. Fast ultrasound beam prediction for linear and regular two-dimensional arrays.

    PubMed

    Hlawitschka, Mario; McGough, Robert J; Ferrara, Katherine W; Kruse, Dustin E

    2011-09-01

    Real-time beam predictions are highly desirable for the patient-specific computations required in ultrasound therapy guidance and treatment planning. To address the longstanding issue of the computational burden associated with calculating the acoustic field in large volumes, we use graphics processing unit (GPU) computing to accelerate the computation of monochromatic pressure fields for therapeutic ultrasound arrays. In our strategy, we start with acceleration of field computations for single rectangular pistons, and then we explore fast calculations for arrays of rectangular pistons. For single-piston calculations, we employ the fast near-field method (FNM) to accurately and efficiently estimate the complex near-field wave patterns for rectangular pistons in homogeneous media. The FNM is compared with the Rayleigh-Sommerfeld method (RSM) for the number of abscissas required in the respective numerical integrations to achieve 1%, 0.1%, and 0.01% accuracy in the field calculations. Next, algorithms are described for accelerated computation of beam patterns for two different ultrasound transducer arrays: regular 1-D linear arrays and regular 2-D linear arrays. For the array types considered, the algorithm is split into two parts: 1) the computation of the field from one piston, and 2) the computation of a piston-array beam pattern based on a pre-computed field from one piston. It is shown that the process of calculating an array beam pattern is equivalent to the convolution of the single-piston field with the complex weights associated with an array of pistons. Our results show that the algorithms for computing monochromatic fields from linear and regularly spaced arrays can benefit greatly from GPU computing hardware, exceeding the performance of an expensive CPU by more than 100 times using an inexpensive GPU board. For a single rectangular piston, the FNM method facilitates volumetric computations with 0.01% accuracy at rates better than 30 ns per field point

  15. Slit-enabled linear-array photoacoustic tomography with near isotropic spatial resolution in three dimensions

    PubMed Central

    Wang, Yuehang; Wang, Depeng; Zhang, Yumiao; Geng, Jumin; Lovell, Jonathan F.; Xia, Jun

    2016-01-01

    Due to its unique capability of visualizing optical absorption in deep tissues, photoacoustic tomography is increasingly used in biomedical imaging. Among various types of transducer arrays, the linear array is perhaps the most widely used in photoacoustic tomography, because it is commercially available and readily allows ultrasound imaging. However, the three-dimensional imaging capability of a linear array is limited, due to its poor elevational resolution. While various scanning schemes have been proposed to address this problem, they all suffer from long scanning time. To address this issue, we introduce slit-enabled three-dimensional photoacoustic tomography. The metal slit, placed at the array focus, causes the incoming photoacoustic waves to diffract along the elevation direction and hence significantly improves the elevation detection aperture and resolution. We tested the new system in both phantoms and animals. The slit improves the elevation resolution by ten times without compromising scanning time. PMID:26696175

  16. Isotropic-resolution linear-array-based photoacoustic computed tomography through inverse Radon transform

    NASA Astrophysics Data System (ADS)

    Li, Guo; Xia, Jun; Li, Lei; Wang, Lidai; Wang, Lihong V.

    2015-03-01

    Linear transducer arrays are readily available for ultrasonic detection in photoacoustic computed tomography. They offer low cost, hand-held convenience, and conventional ultrasonic imaging. However, the elevational resolution of linear transducer arrays, which is usually determined by the weak focus of the cylindrical acoustic lens, is about one order of magnitude worse than the in-plane axial and lateral spatial resolutions. Therefore, conventional linear scanning along the elevational direction cannot provide high-quality three-dimensional photoacoustic images due to the anisotropic spatial resolutions. Here we propose an innovative method to achieve isotropic resolutions for three-dimensional photoacoustic images through combined linear and rotational scanning. In each scan step, we first elevationally scan the linear transducer array, and then rotate the linear transducer array along its center in small steps, and scan again until 180 degrees have been covered. To reconstruct isotropic three-dimensional images from the multiple-directional scanning dataset, we use the standard inverse Radon transform originating from X-ray CT. We acquired a three-dimensional microsphere phantom image through the inverse Radon transform method and compared it with a single-elevational-scan three-dimensional image. The comparison shows that our method improves the elevational resolution by up to one order of magnitude, approaching the in-plane lateral-direction resolution. In vivo rat images were also acquired.

  17. A Wide Dynamic Range Tapped Linear Array Image Sensor

    NASA Astrophysics Data System (ADS)

    Washkurak, William D.; Chamberlain, Savvas G.; Prince, N. Daryl

    1988-08-01

    magnitide are obtained. To achieve the short integration times necessary in acousto-optic applications. t he wide dynamic range detector has been implemented into a tapped array architecture with eight outputs and 256 photoelements. Operation of each 01)1,1)111 at 16 MHz yields detector integration times of 2 micro-seconds. Buried channel two phase CCD shift register technology is utilized to minimize image sensor noise improve video output rates and increase ease of operation.

  18. Linear CCD attitude measurement system based on the identification of the auxiliary array CCD

    NASA Astrophysics Data System (ADS)

    Hu, Yinghui; Yuan, Feng; Li, Kai; Wang, Yan

    2015-10-01

    Object to the high precision flying target attitude measurement issues of a large space and large field of view, comparing existing measurement methods, the idea is proposed of using two array CCD to assist in identifying the three linear CCD with multi-cooperative target attitude measurement system, and to address the existing nonlinear system errors and calibration parameters and more problems with nine linear CCD spectroscopic test system of too complicated constraints among camera position caused by excessive. The mathematical model of binocular vision and three linear CCD test system are established, co-spot composition triangle utilize three red LED position light, three points' coordinates are given in advance by Cooperate Measuring Machine, the red LED in the composition of the three sides of a triangle adds three blue LED light points as an auxiliary, so that array CCD is easier to identify three red LED light points, and linear CCD camera is installed of a red filter to filter out the blue LED light points while reducing stray light. Using array CCD to measure the spot, identifying and calculating the spatial coordinates solutions of red LED light points, while utilizing linear CCD to measure three red LED spot for solving linear CCD test system, which can be drawn from 27 solution. Measured with array CCD coordinates auxiliary linear CCD has achieved spot identification, and has solved the difficult problems of multi-objective linear CCD identification. Unique combination of linear CCD imaging features, linear CCD special cylindrical lens system is developed using telecentric optical design, the energy center of the spot position in the depth range of convergence in the direction is perpendicular to the optical axis of the small changes ensuring highprecision image quality, and the entire test system improves spatial object attitude measurement speed and precision.

  19. Low cost silicon solar cell array

    NASA Technical Reports Server (NTRS)

    Bartels, F. T. C.

    1974-01-01

    The technological options available for producing low cost silicon solar cell arrays were examined. A project value of approximately $250/sq m and $2/watt is projected, based on mass production capacity demand. Recommendations are included for the most promising cost reduction options.

  20. Performance analysis of structured gradient algorithm. [for adaptive beamforming linear arrays

    NASA Technical Reports Server (NTRS)

    Godara, Lal C.

    1990-01-01

    The structured gradient algorithm uses a structured estimate of the array correlation matrix (ACM) to estimate the gradient required for the constrained least-mean-square (LMS) algorithm. This structure reflects the structure of the exact array correlation matrix for an equispaced linear array and is obtained by spatial averaging of the elements of the noisy correlation matrix. In its standard form the LMS algorithm does not exploit the structure of the array correlation matrix. The gradient is estimated by multiplying the array output with the receiver outputs. An analysis of the two algorithms is presented to show that the covariance of the gradient estimated by the structured method is less sensitive to the look direction signal than that estimated by the standard method. The effect of the number of elements on the signal sensitivity of the two algorithms is studied.

  1. The Santa Barbara Research Center multimodule shortwave IR linear array and scene simulator

    NASA Technical Reports Server (NTRS)

    Cizdziel, Philip; Merlo, Thomas; Kormos, Karen; Fuquay, Ralph

    1988-01-01

    Alignment test results and scene simulator imagery are presented for a 1 x 1280 element linear assembly consisting of 5 end-butted modules. The modules include a Si readout chip, a 256 element photovoltaic HgCdTe detector array, and a Si/sapphire carrier. At 145 K, the operation of the LPE shortwave HgCdTE detector array yielded Resistance Area products of 420,000 ohm-sq cm. The results demonstrate the ability to fabricate high-performance, long linear multimodule shortwave IR focal planes for space applications.

  2. Parametric Studies Of Lightweight Reflectors Supported On Linear Actuator Arrays

    NASA Astrophysics Data System (ADS)

    Seibert, George E.

    1987-10-01

    , describes the extent to which the deflection under a point force is localized by the shell's curvature. The deflection shape is typically a near-gaussian "bump" with a zero-crossing at a local radius of approximately 3.5 characteristic lengths. The amplitude is a function of the shells elastic modulus, radius, and thickness, and is linearly proportional to the applied force. This basic shell behavior is well-treated in an excellent set of papers by Eric Reissner entitled "Stresses and Small Displacements of Shallow Spherical Shells".1'2 Building on the insight offered by these papers, we developed our design tools around two derived parameters, the ratio of the mirror's diameter to its characteristic length (D/l), and the ratio of the actuator spacing to the characteristic length (b/l). The D/1 ratio determines the "finiteness" of the shell, or its dependence on edge boundary conditions. For D/1 values greater than 10, the influence of edges is almost totally absent on interior behavior. The b/1 ratio, the basis of all our normalizations is the most universal term in the description of correctability or ratio of residual/input errors. The data presented in the paper, shows that the rms residual error divided by the peak amplitude of the input error function is related to the actuator spacing to characteristic length ratio by the following expression RMS Residual Error b 3.5 k (I) (1) Initial Error Ampl. The value of k ranges from approximately 0.001 for low spatial frequency initial errors up to 0.05 for higher error frequencies (e.g. 5 cycles/diameter). The studies also yielded insight to the forces required to produce typical corrections at both the center and edges of the mirror panels. Additionally, the data lends itself to rapid evaluation of the effects of trading faceplate weight for increased actuator count,

  3. Optimized hyper beamforming of linear antenna arrays using collective animal behaviour.

    PubMed

    Ram, Gopi; Mandal, Durbadal; Kar, Rajib; Ghoshal, Sakti Prasad

    2013-01-01

    A novel optimization technique which is developed on mimicking the collective animal behaviour (CAB) is applied for the optimal design of hyper beamforming of linear antenna arrays. Hyper beamforming is based on sum and difference beam patterns of the array, each raised to the power of a hyperbeam exponent parameter. The optimized hyperbeam is achieved by optimization of current excitation weights and uniform interelement spacing. As compared to conventional hyper beamforming of linear antenna array, real coded genetic algorithm (RGA), particle swarm optimization (PSO), and differential evolution (DE) applied to the hyper beam of the same array can achieve reduction in sidelobe level (SLL) and same or less first null beam width (FNBW), keeping the same value of hyperbeam exponent. Again, further reductions of sidelobe level (SLL) and first null beam width (FNBW) have been achieved by the proposed collective animal behaviour (CAB) algorithm. CAB finds near global optimal solution unlike RGA, PSO, and DE in the present problem. The above comparative optimization is illustrated through 10-, 14-, and 20-element linear antenna arrays to establish the optimization efficacy of CAB.

  4. a Method for Self-Calibration in Satellite with High Precision of Space Linear Array Camera

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Qian, Fangming; Miao, Yuzhe; Wang, Rongjian

    2016-06-01

    At present, the on-orbit calibration of the geometric parameters of a space surveying camera is usually processed by data from a ground calibration field after capturing the images. The entire process is very complicated and lengthy and cannot monitor and calibrate the geometric parameters in real time. On the basis of a large number of on-orbit calibrations, we found that owing to the influence of many factors, e.g., weather, it is often difficult to capture images of the ground calibration field. Thus, regular calibration using field data cannot be ensured. This article proposes a real time self-calibration method for a space linear array camera on a satellite using the optical auto collimation principle. A collimating light source and small matrix array CCD devices are installed inside the load system of the satellite; these use the same light path as the linear array camera. We can extract the location changes of the cross marks in the matrix array CCD to determine the real-time variations in the focal length and angle parameters of the linear array camera. The on-orbit status of the camera is rapidly obtained using this method. On one hand, the camera's change regulation can be mastered accurately and the camera's attitude can be adjusted in a timely manner to ensure optimal photography; in contrast, self-calibration of the camera aboard the satellite can be realized quickly, which improves the efficiency and reliability of photogrammetric processing.

  5. Optimized Hyper Beamforming of Linear Antenna Arrays Using Collective Animal Behaviour

    PubMed Central

    Ram, Gopi; Mandal, Durbadal; Kar, Rajib; Ghoshal, Sakti Prasad

    2013-01-01

    A novel optimization technique which is developed on mimicking the collective animal behaviour (CAB) is applied for the optimal design of hyper beamforming of linear antenna arrays. Hyper beamforming is based on sum and difference beam patterns of the array, each raised to the power of a hyperbeam exponent parameter. The optimized hyperbeam is achieved by optimization of current excitation weights and uniform interelement spacing. As compared to conventional hyper beamforming of linear antenna array, real coded genetic algorithm (RGA), particle swarm optimization (PSO), and differential evolution (DE) applied to the hyper beam of the same array can achieve reduction in sidelobe level (SLL) and same or less first null beam width (FNBW), keeping the same value of hyperbeam exponent. Again, further reductions of sidelobe level (SLL) and first null beam width (FNBW) have been achieved by the proposed collective animal behaviour (CAB) algorithm. CAB finds near global optimal solution unlike RGA, PSO, and DE in the present problem. The above comparative optimization is illustrated through 10-, 14-, and 20-element linear antenna arrays to establish the optimization efficacy of CAB. PMID:23970843

  6. Discrimination of trace nitroaromatics using linear discriminant analysis on aerosol jet printed fluorescent sensor arrays

    NASA Astrophysics Data System (ADS)

    Bolse, N.; Eckstein, R.; Schend, M.; Habermehl, A.; Hernandez-Sosa, G.; Eschenbaum, C.; Lemmer, U.

    2017-05-01

    In this work, we report on fluorescent sensor arrays fabricated by aerosol jet printing on glass substrates to detect explosives-related nitroaromatic species. The printed sensor arrays consist of six different fluorescent polymers responding to nitroaromatic vapors through a photo-induced electron transfer. This results in a quenched fluorescence proportional to the vapor concentration. Distinct fluorescence quenching patterns are detected for nitroaromatic species including nitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene. The detected fingerprints are evaluated at low concentrations of only 1, 3 and 10 parts-per-billion in air. Linear discriminant analysis is used to train each sensor array enabling the discrimination of the target analyte vapors. To investigate the reproducibility of multiple sensor arrays on a single substrate, the measured fluorescence quenching patterns are used to benchmark the linear discriminant models. For this purpose, the target analytes and vapor concentrations are predicted for each sensor array. On average, we report low and reproducible misclassification rates of about 4 % indicating excellent discriminatory abilities at low concentrations close to the detection limits. We conclude that digital printing of fluorescent polymers offers the potential to realize low-cost sensor arrays for a reliable detection of trace explosives.

  7. Optimization of element length for imaging small volumetric reflectors with linear ultrasonic arrays

    NASA Astrophysics Data System (ADS)

    Barber, T. S.; Wilcox, P. D.; Nixon, A. D.

    2016-02-01

    A 3D ultrasonic simulation study is presented, aimed at understanding the effect of element length for imaging small volumetric flaws with linear arrays in ultrasonically noisy materials. The geometry of a linear array can be described by the width, pitch and total number of the elements along with the length perpendicular to imaging plane. This paper is concerned with the latter parameter, which tends to be ignored in array optimization studies and is often chosen arbitrarily for industrial array inspections. A 3D analytical model based on imaging a point target is described, validated and used to make calculations of relative Signal-to-Noise Ratio (SNR) as a function of element length. SNR is found to be highly sensitive to element length with a 12dB variation observed over the length range investigated. It is then demonstrated that the optimal length can be predicted directly from the Point Spread Function (PSF) of the imaging system as well as the natural focal point of the array element from 2D beam profiles perpendicular to the imaging plane. This result suggests that the optimal length for any imaging position can be predicted without the need for a full 3D model and is independent of element pitch and the number of elements. Array element design guidelines are then described with respect to wavelength and extensions of these results are discussed for application to realistically-sized defects and coarse-grained materials.

  8. Linear array implementation of the EM algorithm for PET image reconstruction

    SciTech Connect

    Rajan, K.; Patnaik, L.M.; Ramakrishna, J.

    1995-08-01

    The PET image reconstruction based on the EM algorithm has several attractive advantages over the conventional convolution back projection algorithms. However, the PET image reconstruction based on the EM algorithm is computationally burdensome for today`s single processor systems. In addition, a large memory is required for the storage of the image, projection data, and the probability matrix. Since the computations are easily divided into tasks executable in parallel, multiprocessor configurations are the ideal choice for fast execution of the EM algorithms. In tis study, the authors attempt to overcome these two problems by parallelizing the EM algorithm on a multiprocessor systems. The parallel EM algorithm on a linear array topology using the commercially available fast floating point digital signal processor (DSP) chips as the processing elements (PE`s) has been implemented. The performance of the EM algorithm on a 386/387 machine, IBM 6000 RISC workstation, and on the linear array system is discussed and compared. The results show that the computational speed performance of a linear array using 8 DSP chips as PE`s executing the EM image reconstruction algorithm is about 15.5 times better than that of the IBM 6000 RISC workstation. The novelty of the scheme is its simplicity. The linear array topology is expandable with a larger number of PE`s. The architecture is not dependant on the DSP chip chosen, and the substitution of the latest DSP chip is straightforward and could yield better speed performance.

  9. Design, Fabrication and Characterization of A Bi-Frequency Co-Linear Array

    PubMed Central

    Wang, Zhuochen; Li, Sibo; Czernuszewicz, Tomasz J; Gallippi, Caterina M.; Liu, Ruibin; Geng, Xuecang

    2016-01-01

    Ultrasound imaging with high resolution and large penetration depth has been increasingly adopted in medical diagnosis, surgery guidance, and treatment assessment. Conventional ultrasound works at a particular frequency, with a −6 dB fractional bandwidth of ~70 %, limiting the imaging resolution or depth of field. In this paper, a bi-frequency co-linear array with resonant frequencies of 8 MHz and 20 MHz was investigated to meet the requirements of resolution and penetration depth for a broad range of ultrasound imaging applications. Specifically, a 32-element bi-frequency co-linear array was designed and fabricated, followed by element characterization and real-time sectorial scan (S-scan) phantom imaging using a Verasonics system. The bi-frequency co-linear array was tested in four different modes by switching between low and high frequencies on transmit and receive. The four modes included the following: (1) transmit low, receive low, (2) transmit low, receive high, (3) transmit high, receive low, (4) transmit high, receive high. After testing, the axial and lateral resolutions of all modes were calculated and compared. The results of this study suggest that bi-frequency co-linear arrays are potential aids for wideband fundamental imaging and harmonic/sub-harmonic imaging. PMID:26661069

  10. A Low-Complexity ESPRIT-Based DOA Estimation Method for Co-Prime Linear Arrays

    PubMed Central

    Sun, Fenggang; Gao, Bin; Chen, Lizhen; Lan, Peng

    2016-01-01

    The problem of direction-of-arrival (DOA) estimation is investigated for co-prime array, where the co-prime array consists of two uniform sparse linear subarrays with extended inter-element spacing. For each sparse subarray, true DOAs are mapped into several equivalent angles impinging on the traditional uniform linear array with half-wavelength spacing. Then, by applying the estimation of signal parameters via rotational invariance technique (ESPRIT), the equivalent DOAs are estimated, and the candidate DOAs are recovered according to the relationship among equivalent and true DOAs. Finally, the true DOAs are estimated by combining the results of the two subarrays. The proposed method achieves a better complexity–performance tradeoff as compared to other existing methods. PMID:27571079

  11. A proof of the Woodward-Lawson sampling method for a finite linear array

    NASA Technical Reports Server (NTRS)

    Somers, Gary A.

    1993-01-01

    An extension of the continuous aperture Woodward-Lawson sampling theorem has been developed for a finite linear array of equidistant identical elements with arbitrary excitations. It is shown that by sampling the array factor at a finite number of specified points in the far field, the exact array factor over all space can be efficiently reconstructed in closed form. The specified sample points lie in real space and hence are measurable provided that the interelement spacing is greater than approximately one half of a wavelength. This paper provides insight as to why the length parameter used in the sampling formulas for discrete arrays is larger than the physical span of the lattice points in contrast with the continuous aperture case where the length parameter is precisely the physical aperture length.

  12. The use of a linear Halbach array combined with a step-SPLITT channel for continuous sorting of magnetic species

    PubMed Central

    Hoyos, Mauricio; Moore, Lee; Williams, P. Stephen; Zborowski, Maciej

    2011-01-01

    The Quadrupole Magnetic Sorter (QMS), employing an annular flow channel concentric with the aperture of a quadrupole magnet, is well established for cell and particle separations. Here we propose a magnetic particle separator comprising a linear array of cylindrical magnets, analogous to the array proposed by Klaus Halbach, mated to a substantially improved form of parallel-plate SPLITT channel, known as the step-SPLITT channel. While the magnetic force and throughput are generally lower than for the QMS, the new separator has advantages in ease of fabrication and the ability to vary the magnetic force to suit the separands. Preliminary experiments yield results consistent with prediction and show promise regarding future separations of cells of biomedical interest. PMID:21399709

  13. The use of a linear Halbach array combined with a step-SPLITT channel for continuous sorting of magnetic species.

    PubMed

    Hoyos, Mauricio; Moore, Lee; Williams, P Stephen; Zborowski, Maciej

    2011-05-01

    The Quadrupole Magnetic Sorter (QMS), employing an annular flow channel concentric with the aperture of a quadrupole magnet, is well established for cell and particle separations. Here we propose a magnetic particle separator comprising a linear array of cylindrical magnets, analogous to the array proposed by Klaus Halbach, mated to a substantially improved form of parallel-plate SPLITT channel, known as the step-SPLITT channel. While the magnetic force and throughput are generally lower than for the QMS, the new separator has advantages in ease of fabrication and the ability to vary the magnetic force to suit the separands. Preliminary experiments yield results consistent with prediction and show promise regarding future separations of cells of biomedical interest.

  14. Cell adhesion and guidance by micropost-array chemical sensors

    NASA Astrophysics Data System (ADS)

    Pantano, Paul; Quah, Soo-Kim; Danowski, Kristine L.

    2002-06-01

    An array of ~50,000 individual polymeric micropost sensors was patterned across a glass coverslip by a photoimprint lithographic technique. Individual micropost sensors were ~3-micrometers tall and ~8-micrometers wide. The O2-sensitive micropost array sensors (MPASs) comprised a ruthenium complex encapsulated in a gas permeable photopolymerizable siloxane. The pH-sensitive MPASs comprised a fluorescein conjugate encapsulated in a photocrosslinkable poly(vinyl alcohol)-based polymer. PO2 and pH were quantitated by acquiring MPAS luminescence images with an epifluorescence microscope/charge coupled device imaging system. O2-sensitive MPASs displayed linear Stern-Volmer quenching behavior with a maximum Io/I of ~8.6. pH-sensitive MPASs displayed sigmoidal calibration curves with a pKa of ~5.8. The adhesion of undifferentiated rat pheochromocytoma (PC12) cells across these two polymeric surface types was investigated. The greatest PC12 cell proliferation and adhesion occurred across the poly(vinyl alcohol)-based micropost arrays relative to planar poly(vinyl alcohol)-based surfaces and both patterned and planar siloxane surfaces. An additional advantage of the patterned MPAS layers relative to planar sensing layers was the ability to direct the growth of biological cells. Preliminary data is presented whereby nerve growth factor-differentiated PC12 cells grew neurite-like processes that extended along paths defined by the micropost architecture.

  15. Bipolar battery with array of sealed cells

    DOEpatents

    Kaun, Thomas D.; Smaga, John A.

    1987-01-01

    A lithium alloy/metal sulfide battery as a dipolar battery is disclosed with an array of stacked cells with the anode and cathode electrode materials in each cell sealed in a confining structure and separated from one another except across separator material interposed therebetween. The separator material is contained in a module having separate perforated metallic sheets that sandwich opposite sides of the separator material for the cell and an annular insulating spacer that surrounds the separator material beyond the perforations and is also sandwiched between and sealed to the sheets. The peripheral edges of the sheets project outwardly beyond the spacer, traverse the side edges of the adjacent electrode material to form cup-like electrode holders, and are fused to the adjacent current collector or end face members of the array. Electrolyte is infused into the electrolyte cavity through the perforations of one of the metallic sheets with the perforations also functioning to allow ionic conductance across the separator material between the adjacent electrodes. A gas-tight housing provides an enclosure of the array.

  16. Cell array fabrication by plasma nanotexturing

    NASA Astrophysics Data System (ADS)

    Kontziampasis, Dimitrios; Bourkoula, Athanasia; Petrou, Panagiota; Tserepi, Angeliki; Kakabakos, Sotirios; Gogolides, Evangelos

    2013-05-01

    Cell behavior (i.e. attachment, proliferation, etc.) on nanostructured surfaces is currently a hot topic throughout the scientific community. However, studies often show diverging results due to differences in cells, local surface chemistry, and nanotopography fabrication methods. In this study, we use Oxygen plasma etching to both randomly nanotexture a PMMA surface and change its surface chemistry. We find that 3T3 cells behave quite differently on flat PMMA surfaces as compared to nanotextured ones, showing an on-off attachment behavior. Work is under progress to exploit this effect allowing selective cell capturing, and creation of cell arrays in adjacent plasma-nanotextured/smooth areas using a stencil mask during etching.

  17. Damage characterization using guided-wave linear arrays and image compounding techniques.

    PubMed

    Higuti, Ricardo T; Martínez-Graullera, Oscar; Martín, Carlos J; Octavio, Alberto; Elvira, Luis; Montero de Espinosa, Francisco

    2010-09-01

    In this work, a high-resolution imaging method for the inspection of isotropic plate-like structures using linear arrays and Lamb waves is proposed. The evaluation of these components is limited by the low dynamic range resulting from main lobe and side lobe field patterns, and from the narrowband nature of the Lamb waves. Based on a full matrix array, synthetic aperture technique using all emitter-receiver combinations, different images from the same object are obtained by using different apodization coefficients, which are related to a trade-off between main lobe width and relative side lobe level. Several image compounding strategies have been tested and a new algorithm, based on apodization and polarity diversities between signals, is proposed. However, some effects, such as the dead zone close to the array and reverberations caused by interactions of the wavefront and defects, still limit the quality of the images. The use of spatial diversity, obtained by an additional array, introduces complementary information about the defects and improves the results of the proposed algorithm, producing high-resolution, high-contrast images. Experimental results are shown for a 1-mm-thick isotropic aluminum plate with artificial defects using linear arrays formed by 30 piezoelectric elements, with the low dispersion symmetric mode S0 at the frequency of 330 kHz.

  18. Airborne Linear Array Image Geometric Rectification Method Based on Unequal Segmentation

    NASA Astrophysics Data System (ADS)

    Li, J. M.; Li, C. R.; Zhou, M.; Hu, J.; Yang, C. M.

    2016-06-01

    As the linear array sensor such as multispectral and hyperspectral sensor has great potential in disaster monitoring and geological survey, the quality of the image geometric rectification should be guaranteed. Different from the geometric rectification of airborne planar array images or multi linear array images, exterior orientation elements need to be determined for each scan line of single linear array images. Internal distortion persists after applying GPS/IMU data directly to geometrical rectification. Straight lines may be curving and jagged. Straight line feature -based geometrical rectification algorithm was applied to solve this problem, whereby the exterior orientation elements were fitted by piecewise polynomial and evaluated with the straight line feature as constraint. However, atmospheric turbulence during the flight is unstable, equal piecewise can hardly provide good fitting, resulting in limited precision improvement of geometric rectification or, in a worse case, the iteration cannot converge. To solve this problem, drawing on dynamic programming ideas, unequal segmentation of line feature-based geometric rectification method is developed. The angle elements fitting error is minimized to determine the optimum boundary. Then the exterior orientation elements of each segment are fitted and evaluated with the straight line feature as constraint. The result indicates that the algorithm is effective in improving the precision of geometric rectification.

  19. Linear laser diode arrays for improvement in optical disk recording for space stations

    NASA Technical Reports Server (NTRS)

    Alphonse, G. A.; Carlin, D. B.; Connolly, J. C.

    1990-01-01

    The design and fabrication of individually addressable laser diode arrays for high performance magneto-optic recording systems are presented. Ten diode arrays with 30 mW cW light output, linear light vs. current characteristics and single longitudinal mode spectrum were fabricated using channel substrate planar (CSP) structures. Preliminary results on the inverse CSP structure, whose fabrication is less critically dependent on device parameters than the CSP, are also presented. The impact of systems parameters and requirements, in particular, the effect of feedback on laser design is assessed, and techniques to reduce feedback or minimize its effect on systems performance, including mode-stabilized structures, are evaluated.

  20. Asymmetric transport of light in linearly arrayed metallic nano-particles

    NASA Astrophysics Data System (ADS)

    Horchani, R.

    2016-02-01

    A strong asymmetric light transport in a linear chain of spherical and equidistantly spaced silver metal nano-particles (MNPs) located near a substrate is reported. The contrast ratio of the proposed structure is above 0.95. We have studied the propagation of light in the array with respect to the metal and the size of the last nano-particle of the chain and the nature of the substrate. It is shown also that the presence of a copper or gold substrate enhance the guiding properties of the array. This structure opens the possibility to design various optical devices such as broadband antennae and optical diodes.

  1. Asymmetric transport of light in linearly arrayed metallic nano-particles

    NASA Astrophysics Data System (ADS)

    Aroua, W.; Horchani, R.; AbdelMalek, F.; Haxha, S.; Kamli, Ali A.

    2016-09-01

    A strong asymmetric light transport in a linear chain of spherical and equidistantly spaced silver metal nano-particles (MNPs) located near a substrate is reported. The contrast ratio of the proposed structure is above 0.95. We have studied the propagation of light in the array with respect to the metal and the size of the last nano-particle of the chain and the nature of the substrate. It is shown also that the presence of a copper or gold substrate enhance the guiding properties of the array. This structure opens the possibility to design various optical devices such as broadband antennae and optical diodes.

  2. Acoustic contrast control in an arc-shaped area using a linear loudspeaker array.

    PubMed

    Zhao, Sipei; Qiu, Xiaojun; Burnett, Ian

    2015-02-01

    This paper proposes a method of creating acoustic contrast control in an arc-shaped area using a linear loudspeaker array. The boundary of the arc-shaped area is treated as the envelope of the tangent lines that can be formed by manipulating the phase profile of the loudspeakers in the array. When compared with the existing acoustic contrast control method, the proposed method is able to generate sound field inside an arc-shaped area and achieve a trade-off between acoustic uniformity and acoustic contrast. The acoustic contrast created by the proposed method increases while the acoustic uniformity decreases with frequency.

  3. Sensitivity of linear CCD array based film scanners used for film dosimetry

    SciTech Connect

    Devic, Slobodan; Wang Yizhen; Tomic, Nada; Podgorsak, Ervin B.

    2006-11-15

    Film dosimetry is commonly performed by using linear CCD array transmission optical densitometers. However, these devices suffer from a variation in response along the detector array. If not properly corrected for, this nonuniformity may lead to significant overestimations of the measured dose as one approaches regions close to the edges of the scanning region. In this note, we present measurements of the spatial response of an AGFA Arcus II document scanner used for radiochromic film dosimetry. Results and methods presented in this work can be generalized to other CCD based transmission scanners used for film dosimetry employing either radiochromic or radiographic films.

  4. Power Pattern Sensitivity to Calibration Errors and Mutual Coupling in Linear Arrays through Circular Interval Arithmetics

    PubMed Central

    Anselmi, Nicola; Salucci, Marco; Rocca, Paolo; Massa, Andrea

    2016-01-01

    The sensitivity to both calibration errors and mutual coupling effects of the power pattern radiated by a linear array is addressed. Starting from the knowledge of the nominal excitations of the array elements and the maximum uncertainty on their amplitudes, the bounds of the pattern deviations from the ideal one are analytically derived by exploiting the Circular Interval Analysis (CIA). A set of representative numerical results is reported and discussed to assess the effectiveness and the reliability of the proposed approach also in comparison with state-of-the-art methods and full-wave simulations. PMID:27258274

  5. A Hybrid Particle Swarm with Differential Evolution Operator Approach (DEPSO) for Linear Array Synthesis

    NASA Astrophysics Data System (ADS)

    Sarkar, Soham; Das, Swagatam

    In recent years particle swarm optimization emerges as one of the most efficient global optimization tools. In this paper, a hybrid particle swarm with differential evolution operator, termed DEPSO, is applied for the synthesis of linear array geometry. Here, the minimum side lobe level and null control, both are obtained by optimizing the spacing between the array elements by this technique. Moreover, a statistical comparison is also provided to establish its performance against the results obtained by Genetic Algorithm (GA), classical Particle Swarm Optimization (PSO), Tabu Search Algorithm (TSA), Differential Evolution (DE) and Memetic Algorithm (MA).

  6. Particle velocity gradient based acoustic mode beamforming for short linear vector sensor arrays.

    PubMed

    Gur, Berke

    2014-06-01

    In this paper, a subtractive beamforming algorithm for short linear arrays of two-dimensional particle velocity sensors is described. The proposed method extracts the highly directional acoustic modes from the spatial gradients of the particle velocity field measured at closely spaced sensors along the array. The number of sensors in the array limits the highest order of modes that can be extracted. Theoretical analysis and numerical simulations indicate that the acoustic mode beamformer achieves directivity comparable to the maximum directivity that can be obtained with differential microphone arrays of equivalent aperture. When compared to conventional delay-and-sum beamformers for pressure sensor arrays, the proposed method achieves comparable directivity with 70%-85% shorter apertures. Moreover, the proposed method has additional capabilities such as high front-back (port-starboard) discrimination, frequency and steer direction independent response, and robustness to correlated ambient noise. Small inter-sensor spacing that results in very compact apertures makes the proposed beamformer suitable for space constrained applications such as hearing aids and short towed arrays for autonomous underwater platforms.

  7. Collective Interaction in a Linear Array of Supersonic Rectangular Jets: A Linear Spatial Instability Study

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    1999-01-01

    A linear spatial instability model for multiple spatially periodic supersonic rectangular jets is solved using Floquet-Bloch theory. It is assumed that in the region of interest a coherent wave can propagate. For the case studied large spatial growth rates are found. This work is motivated by an increase in mixing found in experimental measurements of spatially periodic supersonic rectangular jets with phase-locked screech and edge tone feedback locked subsonic jets. The results obtained in this paper suggests that phase-locked screech or edge tones may produce correlated spatially periodic jet flow downstream of the nozzles which creates a large span wise multi-nozzle region where a coherent wave can propagate. The large spatial growth rates for eddies obtained by model calculation herein are related to the increased mixing since eddies are the primary mechanism that transfer energy from the mean flow to the large turbulent structures. Calculations of spacial growth rates will be presented for a set of relative Mach numbers and spacings for which experimental measurements have been made. Calculations of spatial growth rates are presented for relative Mach numbers from 1.25 to 1.75 with ratios of nozzle spacing to nozzle width ratios from s/w(sub N) = 4 to s/w(sub N) = 13.7. The model may be of significant scientific and engineering value in the quest to understand and construct supersonic mixer-ejector nozzles which provide increased mixing and reduced noise.

  8. Microwell Arrays for Studying Many Individual Cells

    NASA Technical Reports Server (NTRS)

    Folch, Albert; Kosar, Turgut Fettah

    2009-01-01

    "Laboratory-on-a-chip" devices that enable the simultaneous culturing and interrogation of many individual living cells have been invented. Each such device includes a silicon nitride-coated silicon chip containing an array of micromachined wells sized so that each well can contain one cell in contact or proximity with a patch clamp or other suitable single-cell-interrogating device. At the bottom of each well is a hole, typically 0.5 m wide, that connects the well with one of many channels in a microfluidic network formed in a layer of poly(dimethylsiloxane) on the underside of the chip. The microfluidic network makes it possible to address wells (and, thus, cells) individually to supply them with selected biochemicals. The microfluidic channels also provide electrical contact to the bottoms of the wells.

  9. Array error calibration methods in downward-looking linear-array three-dimensional synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Tan, Weixian; Huang, Pingping; Han, Kuoye; Liu, Qi; Peng, Xueming

    2016-04-01

    In order to achieve high-precision three-dimensional (3-D) imaging with an airborne downward-looking linear-array 3-D synthetic aperture radar (LA-3D-SAR), a uniform virtual antenna array can be obtained by aperture synthesis of the cross-track sparse multiple-input-multiple-output array. However, the actual 3-D imaging quality is unavoidably degraded by array errors such as the multichannel amplitude-phase errors due to the nonideal antenna characteristics, and the virtual element position errors due to vibrations and motion measurement deviations. We investigate the effects of these errors on the forms and the degrees of image quality degradation and consider the use of corresponding calibration methods to eliminate the effects of errors. For the multichannel amplitude-phase errors, the target response is subject to an integrated sidelobe level increase introduced by the phase error, which can be calibrated based on external (parallel or point target) calibrators, as proposed in the paper. For the virtual element position errors, they mainly the result of contrast degradation and noise in the image along the cross-track direction and have little impact on the range and along-track directions. The imaging performance is more sensitive to the error component in the height direction as compared to other components, the precision requirement of which should be established as the calibration reference. A calibration method based on time-divided active calibrators is proposed to estimate and correct the virtual element position errors. Both numerical simulations and real data experiments have shown the validity of the analyses as well as the effectiveness of the proposed calibration methods.

  10. Design and implementation of non-contact detection system for catenary based on double linear array cameras

    NASA Astrophysics Data System (ADS)

    Chen, Peng; Xu, Cheng; Li, Zhiqi; Xu, Zisang

    2017-04-01

    The detection of catenary geometric parameters is a very important problem in railway infrastructure measurement. In this paper, a high resolution linear array CCD is used as the photosensitive element, and FPGA is used as the main controller to design the data acquisition system of linear array camera, and a non-contact detection system of catenary geometry parameters based on double linear array cameras is implemented. According to the intensity of linear array CCD output signal, and the adaptive adjustment algorithm of exposure intensity is achieved, so the optical integration time is changed in real time. In order to improve the bandwidth limitation of data transmission, the calibration algorithm of pixel position in the system is completed by FPGA, which improved the response speed of the system. The experimental results show that the scan frequency of linear array camera can reach 6MHz, the measurement error is controlled at mm level, and it has good accuracy and stability.

  11. Novel measurement method of infrared laser beam divergence angle based on two linear array CCDs

    NASA Astrophysics Data System (ADS)

    Xie, Jing; Chen, Haiqing; Tan, Zuojun; Hou, Dejia; Wang, Xianfeng

    2013-09-01

    In the practical application of infrared lasers, an infrared linear laser beam of 90°×2° is shaped to meet special demand. So it is very important to test its beam divergence angle which reflects long-distance transmission characteristics. Many approaches are proposed, such as area array CCD single imaging method, two plate reflecting mirrors multi imaging method, distorted diffraction grating multi imaging method and so on. Nevertheless, these methods only can be used to detect infrared laser beam whose spot shape is small and elliptical. Actually if the view angle of the infrared linear laser beam is greater than 90° in the horizontal direction, the area array CCD cannot detect the whole light spot. So we proposed a two linear array CCDs scanning imaging measurement method. The two linear array CCDs are placed at Z1 position of near field and Z2 position of far field respectively, and they are separated by an angle Φ. Beam width in two positions can be calculated by light intensity distribution curves which are measured by linear array CCD. Meanwhile, beam width fits linear equation in the far field, so beam divergence angle can be obtained by two point line fitting. This method is based on a real-time and automatic measurement system which consists of infrared laser optical transmitter, control module, imaging system and data processing. The infrared laser optical transmitter is controlled by control module to rotate every one degree. After scanning is completed, we can acquire the spot image and beam divergence angle curve by imaging system and data processing. This novel arrangement provides a precise and comprehensive measurement. Compared to other methods, this method can not only be used for measuring beam divergence angle of infrared linear laser beam, but also for detecting the uniformity of energy distribution and assembling laser optical transmitter. Experimental results indicate that measurement values are in the acceptable range, measurement

  12. 250 kA compact linear transformer driver for wire array z-pinch loads

    NASA Astrophysics Data System (ADS)

    Bott, S. C.; Haas, D. M.; Madden, R. E.; Ueda, U.; Eshaq, Y.; Collins, G., IV; Gunasekera, K.; Mariscal, D.; Peebles, J.; Beg, F. N.; Mazarakis, M.; Struve, K.; Sharpe, R.

    2011-05-01

    We present the application of a short rise (˜150ns) 250 kA linear transformer driver (LTD) to wire array z-pinch loads for the first time. The generator is a modification of a previous driver in which a new conical power feed provides a low inductance coupling to wire loads. Performance of the new design using both short circuit and plasma loads is presented and discussed. The final design delivers ˜200kA to a wire array load which is in good agreement with SCREAMER calculations using a simplified representative circuit. Example results demonstrate successful experiments using cylindrical, conical, and inverse wire arrays as well as previously published work on x-pinch loads.

  13. CFD Analysis of a Finite Linear Array of Savonius Wind Turbines

    NASA Astrophysics Data System (ADS)

    Belkacem, Belabes; Paraschivoiu, Marius

    2016-09-01

    Vertical axis wind turbines such as Savonius rotors have been shown to be suitable for low wind speeds normally associated with wind resources in all corners of the world. However, the efficiency of the rotor is low. This paper presents results of Computational Fluid Dynamics (CFD) simulations for an array of Savonius rotors that show a significant increase in efficiency. It looks at identifying the effect on the energy yield of a number of turbines placed in a linear array. Results from this investigation suggest that an increase in the energy yield could be achieved which can reach almost two times than the conventional Savonius wind turbine in the case of an array of 11turbines with a distance of 1.4R in between them. The effect of different TSR values and different wind inlet speeds on the farm has been studied for both a synchronous and asynchronous wind farm.

  14. Microfluidic linear hydrogel array for multiplexed single nucleotide polymorphism (SNP) detection.

    PubMed

    Jung, Yun Kyung; Kim, Jungkyu; Mathies, Richard A

    2015-03-17

    A PDMS-based microfluidic linear hydrogel array is developed for multiplexed single nucleotide polymorphism (SNP) detection. A sequence of three-dimensional (3D) hydrogel plugs containing the desired DNA probes is prepared by UV polymerization within a PDMS microchannel system. The fluorescently labeled target DNA is then electrophoresed through the sequence of hydrogel plugs for hybridization. Continued electrophoresis provides an electrophoretic wash that removes nonspecific binders. The capture gel array is imaged after washing at various temperatures (temperature gradient electrophoresis) to further distinguish perfect matches from mismatches. The ability of this microdevice to perform multiplex SNP genotyping is demonstrated by analyzing a mixture of model E. coli bacterial targets. This microfluidic hydrogel array is ∼1000 times more sensitive than planar microarrays due to the 3D gel capture, the hybridization time is much shorter due to electrophoretic control of the transport properties, and the stringent wash with temperature gradient electrophoresis enables analysis of single nucleotide mismatches with high specificity.

  15. A new linear array detector for high resolution and low dose digital radiography

    NASA Astrophysics Data System (ADS)

    Bettuzzi, Matteo; Cornacchia, Samantha; Rossi, Massimo; Paltrinieri, Enrica; Morigi, Maria Pia; Brancaccio, Rosa; Romani, Davide; Casali, Franco

    2004-01-01

    At the Department of Physics of the University of Bologna a new intensified linear array detector is under development. The core of the system is a digital intensified CCD camera, the electron bombarded charge coupled device (EBCCD). The main innovation is a coherent rectangular-to-linear fiber optics adapter coupling the 1 in. diameter photocathode of the camera with a linear 129 mm × 1.45 mm strip of Gd 2O 2S:Tb. In this way a high spatial resolution over an extended length is obtained. The detector works as an X-ray scanner by means of a high-precision translation mechanical device to inspect a 13 cm × 18 cm area. A complete characterisation of the system has been made in terms of linearity, dynamic range, modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE). At last, radiographic tests on a set of samples have been made and will be presented.

  16. Linearly polarized light emission from quantum dots with plasmonic nanoantenna arrays.

    PubMed

    Ren, Mengxin; Chen, Mo; Wu, Wei; Zhang, Lihui; Liu, Junku; Pi, Biao; Zhang, Xinzheng; Li, Qunqing; Fan, Shoushan; Xu, Jingjun

    2015-05-13

    Polarizers provide convenience in generating polarized light, meanwhile their adoption raises problems of extra weight, cost, and energy loss. Aiming to realize polarizer-free polarized light sources, herein, we present a plasmonic approach to achieve direct generation of linearly polarized optical waves at the nanometer scale. Periodic slot nanoantenna arrays are fabricated, which are driven by the transition dipole moments of luminescent semiconductor quantum dots. By harnessing interactions between quantum dots and scattered fields from the nanoantennas, spontaneous emission with a high degree of linear polarization is achieved from such hybrid antenna system with polarization perpendicular to antenna slot. We also demonstrate that the polarization is engineerable in aspects of both spectrum and magnitude by tailoring plasmonic resonance of the antenna arrays. Our findings will establish a basis for the development of innovative polarized light-emitting devices, which are useful in optical displays, spectroscopic techniques, optical telecommunications, and so forth.

  17. Non-contact Measurement of Damaged External Tapered Thread Based on Linear Array CCD

    NASA Astrophysics Data System (ADS)

    He, F. J.; Zhang, R. J.; Du, Z. J.; Cui, X. M.

    2006-10-01

    The non-contact measurement of external tapered thread based on linear array CCD is presented to decrease the measuring error caused by local damage area contrast to the measurement with mechanical gauges. The thread is scanned by linear array CCD and the signal is processed by first order difference to obtain thread contour. For the thread with damage on tooth flank and deformation on generating line, the Hough transform and weighted least squares are adopted to reduce the local defects and to set up fitted thread contour equations that can reflect the real dimension. Then the dimensions can be calculated based on these equations according to the definition. The paper also presents the method to evaluate the local damage. Experiment shows that the method is suitable for the measurement of damaged thread.

  18. Photoacoustic imaging of the human forearm using 40 MHz linear-array transducer

    NASA Astrophysics Data System (ADS)

    Zafar, Haroon; Breathnach, Aedán.; Subhash, Hrebesh M.; Leahy, Martin J.

    2014-02-01

    In this work photoacoustic imaging (PAI) based on multi element linear-array transducer, combined with multichannel collecting system was used for in vivo imaging of microcirculation of the human forearm. The Vevo® 2100 LAZR PAT system (VISUALSONICS) was used for imaging which simultaneously collects high-resolution ultrasound and photoacoustic signals. 3D PA and high frequency ultrasound scans, measured 30.5 mm (length) x 14.1 mm (width) x 10 mm (depth) were acquired from the area of forearm skin using 40 MHz frequency transducer at 860 nm wavelength. 3D structural and functional (microcirculation) maps of the forearm skin were obtained. The multi element linear-array transducer based PAI has been found promising in terms of resolution, imaging depth and imaging speed for in vivo microcirculation imaging within human skin.

  19. Realistic photoacoustic image simulations of collections of solid spheres using linear array transducer

    NASA Astrophysics Data System (ADS)

    Karmakar, Subhajit; Hysi, Eno; Kolios, Michael C.; Saha, Ratan K.

    2015-03-01

    A methodology for simulating photoacoustic (PA) images of samples with solid spherical absorbers acquired using linear array transducer is described. Two types of numerical phantoms (i.e., polystyrene beads suspended in agar medium) of two different size regimes were imaged with a 40 MHz linear array transducer utilizing this approach. The frequency domain features and statistics of the simulated signals were quantified for tissue characterization. The midband fit at 40 MHz was found to be about 35 dB higher for the sample with larger beads (radius ~7.36 μm) than that of the sample with smaller particles (radius ~ 1.77 μm). The scale parameter of the generalized gamma distribution function was found to be nearly 51 times greater for the former sample compared to the latter sample. The method developed here shows potential to be used a s a fast simulation tool for the PA imaging of collection of absorbers mimicking biological tissue.

  20. A novel acoustic emission beamforming method with two uniform linear arrays on plate-like structures.

    PubMed

    Xiao, Denghong; He, Tian; Pan, Qiang; Liu, Xiandong; Wang, Jin; Shan, Yingchun

    2014-02-01

    A novel acoustic emission (AE) source localization approach based on beamforming with two uniform linear arrays is proposed, which can localize acoustic sources without accurate velocity, and is particularly suited for plate-like structures. Two uniform line arrays are distributed in the x-axis direction and y-axis direction. The accurate x and y coordinates of AE source are determined by the two arrays respectively. To verify the location accuracy and effectiveness of the proposed approach, the simulation of AE wave propagation in a steel plate based on the finite element method and the pencil-lead-broken experiment are conducted, and the AE signals obtained from the simulations and experiments are analyzed using the proposed method. Moreover, to study the ability of the proposed method more comprehensive, a plate of carbon fiber reinforced plastics is taken for the pencil-lead-broken test, and the AE source localization is also realized. The results indicate that the two uniform linear arrays can localize different sources accurately in two directions even though the localizing velocity is deviated from the real velocity, which demonstrates the effectiveness of the proposed method in AE source localization for plate-like structures.

  1. Broadband ultrasonic linear array using ternary PIN-PMN-PT single crystal.

    PubMed

    Wang, Wei; Zhao, Xiangyong; Or, Siu Wing; Leung, Chung Ming; Zhang, Yaoyao; Jiao, Jie; Luo, Haosu

    2012-09-01

    Ternary Pb(In(1/2)Nb(1/2))O(3)-Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PIN-PMN-PT) single crystal was investigated for potential application in ultrasonic linear array. Orientation and temperature dependences of height extensional electromechanical coupling coefficient k'(33) for PIN-PMN-PT single crystal were studied. It was found that the [001] poled PIN-PMN-PT diced along the [100] direction would achieve a maximum k'(33) (~87%) and the service temperature was up to 110 °C. Ultrasonic linear arrays using PIN-PMN-PT single crystal and PZT ceramic were fabricated and compared. The bandwidth at -6 dB, two-way insertion loss and pulse length of the PIN-PMN-PT array were 98.6%, -45.1 dB, and 0.28 μs, respectively, which were about 25% broader, 3.7dB higher, and 0.08 μs shorter than those of the PZT array. The experimental results agreed well with the theoretical simulation. These superior performances were attributable to the excellent piezoelectric properties of PIN-PMN-PT single crystal.

  2. The linear array multi-band selection device role in remote-sensing instrument design

    NASA Technical Reports Server (NTRS)

    Speaker, E. E.

    1984-01-01

    A figure-of-merit parameter for the scientific utility of multispectral linear array (MLA) instruments for civil remote sensing is presented. The number of spectral band-pair choices available to the user of a given MLA instrument is proposed as a useful measure of the flexibility and overall utility of that particular instrument design. The multiband selection device capability is analyzed mathematically, and a basis for a cost-benefit comparison of alternative multispectral instrument designs is provided.

  3. Annular Arrays Of Solar Cells For Spinning Spacecraft

    NASA Technical Reports Server (NTRS)

    Spilker, Thomas R.

    1995-01-01

    Report proposes annular arrays of solar photovoltaic cells installed on spin-stabilized spacecraft. Annular array faces Sun. Typical array consists of two stacked annuli of solar cells: one annulus fixed about spin axis, while other divided into deployable sectors mounted on dual swing arms and stowed by folding them atop fixed annulus. Once released, deployable sectors swing outward under spring or centrifugal force and expose fixed array so it generates additional power.

  4. Correction of linear-array lidar intensity data using an optimal beam shaping approach

    NASA Astrophysics Data System (ADS)

    Xu, Fan; Wang, Yuanqing; Yang, Xingyu; Zhang, Bingqing; Li, Fenfang

    2016-08-01

    The linear-array lidar has been recently developed and applied for its superiority of vertically non-scanning, large field of view, high sensitivity and high precision. The beam shaper is the key component for the linear-array detection. However, the traditional beam shaping approaches can hardly satisfy our requirement for obtaining unbiased and complete backscattered intensity data. The required beam distribution should roughly be oblate U-shaped rather than Gaussian or uniform. Thus, an optimal beam shaping approach is proposed in this paper. By employing a pair of conical lenses and a cylindrical lens behind the beam expander, the expanded Gaussian laser was shaped to a line-shaped beam whose intensity distribution is more consistent with the required distribution. To provide a better fit to the requirement, off-axis method is adopted. The design of the optimal beam shaping module is mathematically explained and the experimental verification of the module performance is also presented in this paper. The experimental results indicate that the optimal beam shaping approach can effectively correct the intensity image and provide ~30% gain of detection area over traditional approach, thus improving the imaging quality of linear-array lidar.

  5. Suppression of thermal fluctuation placement errors in linear arrays of block copolymer cylinders

    NASA Astrophysics Data System (ADS)

    Carpenter, Corinne L.; Delaney, Kris T.; Fredrickson, Glenn H.

    2017-03-01

    Directed self-assembly (DSA) of block copolymers has attracted much interest for its use as a low-cost, high throughput patterning tool to supplement existing lithographic techniques, and especially for its ability to easily pattern vertical interconnect accesses (VIAs).1 Assembling multiple cylinders in a single template has obvious advantages for feature density increase. However, denser patterning comes at a cost, due to more abundant defect modes2 and increased susceptibility to placement errors due to thermal fluctuations. Linear arrays of cylinders have been shown in a simplified model to contain collective excitations, ultimately leading to unbounded positional variance away from their equilibrium locations in a manner analogous to a one-dimensional crystal.3 In order to reduce this positional uncertainty, we introduce chemically selective stripes on the substrate of the system. These chemoepitaxially patterned regions create an energetic preference for the equilibrium configuration of the system, pinning the VIAs in place. In this study, we use three-dimensional self-consistent field theory (SCFT) simulations and complex Langevin (CL) sampling to investigate the effects of thermal fluctuations on cylinder positions in linear arrays of VIAs with preferentially striped substrates. We interrogate the relationship between stripe interaction strength and positional variance, compare the magnitude of reduction with a Landau-Peierls analysis on a simplified system, and propose a predictive model for placement error in similarly chemo patterned systems. Since the cylinders are flexible, we propose a maximum system height for linear arrays with acceptably low placement error.

  6. Linear azimuthons in circular fiber arrays and optical angular momentum of discrete optical vortices

    SciTech Connect

    Alexeyev, C. N.; Volyar, A. V.; Yavorsky, M. A.

    2009-12-15

    We study the field generated in the outer space by the superposition of modes of a regular circular monomode fiber array. It is shown that a supermode of the fiber array generates a discrete optical vortex; the formula for the topological charge of the vortex is obtained depending on the order of the supermode and the number of fibers in the array. The orbital angular momentum carried by an arbitrary superposition of supermodes is shown to equal the weighted sum of partial angular momenta of supermodes. It is shown that for certain combinations of supermodes the angular momentum comprises along with its intrinsic part also the extrinsic constituent. For such combinations precession of the angular momentum about the propagation axis is demonstrated. It is demonstrated that by combining supermodes one can generate in the array stable regularly rotating linear azimuthons. By creating a phased excitation of certain groups of fibers in the array one can control the global soliton-like motion of the excited domain.

  7. Experimental validation of a coprime linear microphone array for high-resolution direction-of-arrival measurements.

    PubMed

    Xiang, Ning; Bush, Dane; Summers, Jason E

    2015-04-01

    Coprime linear microphone arrays allow for narrower beams with fewer sensors. A coprime microphone array consists of two staggered uniform linear subarrays with M and N microphones, where M and N are coprime with each other. By applying spatial filtering to both subarrays and combining their outputs, M+N-1 microphones yield M⋅N directional bands. In this work, the coprime sampling theory is implemented in the form of a linear microphone array of 16 elements with coprime numbers of 9 and 8. This coprime microphone array is experimentally tested to validate the coprime array theory. Both predicted and measured results are discussed. Experimental results confirm that narrow beampatterns as predicted by the coprime sampling theory can be obtained by the coprime microphone array.

  8. Design and development of a linear Fresnel lens air-cooled photovoltaic module and a stand-alone photovoltaic collector array

    SciTech Connect

    Not Available

    1985-01-01

    A summary description of the design development of a linear Fresnel lens air-cooled photovoltaic collector and a stand-alone photovoltaic collector array is presented. Module performance is characterized by 12.9% electrical efficiency under operational conditions (800 w/m/sup 2/, 20/sup 0/C ambient temperature) and 14.2% electrical efficiency at 28/sup 0/C cell reference temperature. The stand-alone photovoltaic collector array design utilizes eight air-cooled photovoltaic modules and produces a peak output of 2680 watts at 20/sup 0/C ambient temperature and 1000 w/m/sup 2/ direct normal insolation. This corresponds to an overall array electrical efficiency of 12%. A prototype subscale array was fabricated and performance tested and verified the stand-alone array concept.

  9. A 400 KHz line rate 2048 pixel modular SWIR linear array for earth observation applications

    NASA Astrophysics Data System (ADS)

    Anchlia, Ankur; Vinella, Rosa M.; Wouters, Kristof; Gielen, Daphne; Hooylaerts, Peter; Deroo, Pieter; Ruythooren, Wouter; van der Zanden, Koen; Vermeiren, Jan; Merken, Patrick

    2015-10-01

    In this paper, we report about a family of linear imaging FPAs sensitive in the [0.9 - 1.7um] band, developed for high speed applications such as LIDAR, wavelength references and OCT analyzers and also for earth observation applications. Fast linear FPAs can also be used in a wide variety of terrestrial applications, including high speed sorting, electro- and photo-luminesce and medical applications. The arrays are based on a modular ROIC design concept: modules of 512 pixels are stitched during fabrication to achieve 512, 1024 and 2048 pixel arrays. In principle, this concept can be extended to any multiple of 512 pixels, the limiting factor being the pixel yield of long InGaAs arrays and the CTE differences in the hybrid setup. Each 512-pixel module has its own on-chip digital sequencer, analog readout chain and 4 output buffers. This modular concept enables a long-linear array to run at a high line rate of 400 KHz irrespective of the array length, which limits the line rate in a traditional linear array. The pixel has a pitch of 12.5um. The detector frontend is based on CTIA (Capacitor Trans-impedance Amplifier), having 5 selectable integration capacitors giving full well from 62x103e- (gain0) to 40x106e- (gain4). An auto-zero circuit limits the detector bias non-uniformity to 5-10mV across broad intensity levels, limiting the input referred dark signal noise to 20e-rms for Tint=3ms at room temperature. An on-chip CDS that follows the CTIA facilitates removal of Reset/KTC noise, CTIA offsets and most of the 1/f noise. The measured noise of the ROIC is 35e-rms in gain0. At a master clock rate of 60MHz and a minimum integration time of 1.4us, the FPAs reach the highest line rate of 400 KHz.

  10. Linearity Testing of Photovoltaic Cells: Preprint

    SciTech Connect

    Emery, K.; Winter, S.; Pinegar, S.; Nalley D.

    2006-05-01

    Photovoltaic devices are rated in terms of their peak power with respect to a specific spectrum, total irradiance, and temperature. To rate photovoltaic devices, a reference detector is required whose response is linear with total irradiance. This paper describes a procedure to determine the linearity of the short-circuit current (Isc) versus the total irradiance (Etot) by illuminating a reference cell with two lamps. A device is linear if the current measured with both lamps illuminating the cell is the same as the sum of the currents with each lamp illuminating the cell. The two-lamp method is insensitive to the light spectra or spatial nonuniformity changing with irradiance. The two-lamp method is rapid, easy to implement, and does not require operator intervention to change the irradiances. The presence of room light only limits the lowest irradiance that can be evaluated. Unlike other methods, the two-lamp method does not allow the current to be corrected for nonlinear effects.

  11. Liquid cooled, linear focus solar cell receiver

    NASA Astrophysics Data System (ADS)

    Kirpich, A. S.

    1983-12-01

    Separate structures for electrical insulation and thermal conduction which are established within a liquid cooled, linear focus solar cell receiver for use with parabolic or Fresnel optical concentrators are discussed. The receiver includes a V shaped aluminum extrusion with a pair of outer faces each formed with a channel receiving a string of solar cells in thermal contact with the extrusion. Each cell string is attached to a continuous glass cover secured within the channel with spring clips to isolate the string from the external environment. Repair or replacement of solar cells is effected simply by detaching the spring clips to remove the cover/cell assembly without interrupting circulation of coolant fluid through the receiver. The lower surface of the channel in thermal contact with the cells of the string is anodized to establish a suitable standoff voltage capability between the cells and the extrusion. Primary electrical insulation is provided by a dielectric tape disposed between the coolant tube and extrusion. Adjacent solar cells are soldered to interconnect members designed to accommodate thermal expansion and mismatches. The coolant tube is clamped into the extrusion channel with a releasable attachable clamping strip to facilitate easy removal of the receiver from the coolant circuit.

  12. Liquid cooled, linear focus solar cell receiver

    DOEpatents

    Kirpich, Aaron S.

    1985-01-01

    Separate structures for electrical insulation and thermal conduction are established within a liquid cooled, linear focus solar cell receiver for use with parabolic or Fresnel optical concentrators. The receiver includes a V-shaped aluminum extrusion having a pair of outer faces each formed with a channel receiving a string of solar cells in thermal contact with the extrusion. Each cell string is attached to a continuous glass cover secured within the channel with spring clips to isolate the string from the external environment. Repair or replacement of solar cells is effected simply by detaching the spring clips to remove the cover/cell assembly without interrupting circulation of coolant fluid through the receiver. The lower surface of the channel in thermal contact with the cells of the string is anodized to establish a suitable standoff voltage capability between the cells and the extrusion. Primary electrical insulation is provided by a dielectric tape disposed between the coolant tube and extrusion. Adjacent solar cells are soldered to interconnect members designed to accommodate thermal expansion and mismatches. The coolant tube is clamped into the extrusion channel with a releasably attachable clamping strip to facilitate easy removal of the receiver from the coolant circuit.

  13. Liquid cooled, linear focus solar cell receiver

    DOEpatents

    Kirpich, A.S.

    1983-12-08

    Separate structures for electrical insulation and thermal conduction are established within a liquid cooled, linear focus solar cell receiver for use with parabolic or Fresnel optical concentrators. The receiver includes a V-shaped aluminum extrusion having a pair of outer faces each formed with a channel receiving a string of solar cells in thermal contact with the extrusion. Each cell string is attached to a continuous glass cover secured within the channel with spring clips to isolate the string from the external environment. Repair or replacement of solar cells is effected simply by detaching the spring clips to remove the cover/cell assembly without interrupting circulation of coolant fluid through the receiver. The lower surface of the channel in thermal contact with the cells of the string is anodized to establish a suitable standoff voltage capability between the cells and the extrusion. Primary electrical insulation is provided by a dielectric tape disposed between the coolant tube and extrusion. Adjacent solar cells are soldered to interconnect members designed to accommodate thermal expansion and mismatches. The coolant tube is clamped into the extrusion channel with a releasably attachable clamping strip to facilitate easy removal of the receiver from the coolant circuit.

  14. Polarization-sensitive linear plasmonic nanostructures via colloidal lithography with uniaxial colloidal arrays.

    PubMed

    Saracut, V; Giloan, M; Gabor, M; Astilean, S; Farcau, C

    2013-02-01

    The ability of metallic nanostructures to support surface plasmon excitations is widely exploited nowadays for developing new technologies and applications in many fields, like communications, medicine or environment. It is known that the plasmonic response of a nanostructure is strongly dependent on its size and shape, and thus a fine control of these features is required for developing applications. In this paper uniaxial colloidal crystal arrays are prepared by convective self-assembly on DVD surfaces. These are then used as template/mask for metal film deposition, in order to obtain two original kinds of metallic nanostructures with controllable morphology: (i) linear arrays of metal half-shells (LAMHSs) and (ii) arrays of periodically serrated plasmonic strips (PSPSs). Angle-resolved optical transmittance measurements reveal the presence of several surface plasmon resonances, while polarized light transmission demonstrates the anisotropic plasmonic response of both LAMHSs and PSPSs. FDTD simulations support the experimental observations and help in the assignments of observed plasmon modes. The proposed linear metallic nanostructures can prove useful for the design of plasmonic components.

  15. Maximum power transfer from a solar-cell array by sensing array temperature

    NASA Technical Reports Server (NTRS)

    Sussman, M.

    1972-01-01

    A technique is described in which a spacecraft solar-cell array is caused to operate at or near maximum power output over a wide range of environmental conditions. The output of an array temperature sensor is used to vary the duty cycle of a pulse-width-modulated impedance regulator so that the array operates at the voltage of maximum power. A resistance-type temperature sensor was found to be applicable for most spacecraft missions. However, a solar cell used as a temperature sensor has the advantage of negligible transient errors on lightweight arrays for orbiting spacecraft.

  16. Synchronization behavior in linear arrays of negative differential resistance circuit elements

    NASA Astrophysics Data System (ADS)

    Xu, Huidong; Teitsworth, Stephen

    2008-03-01

    We study the electronic transport properties in a linear array of nonlinear circuit elements that exhibit negative differential resistance, and find that state-cluster synchronization emerges when there is heterogeneity in the element properties. This type of synchronization is associated with a non-uniform spatial distribution of total applied voltage across the array elements, as well as the formation of multiple stable branches in computed current-voltage curves for the entire array. Unlike most synchronizing systems studied previously [1], this system possesses coupling between elements that displays both positive and negative feedback depending on the state of each element. An empirical order parameter is defined which quantifies the degree of synchronization. We also find that the degree of synchronization is strongly dependent on the ramping rate of the total applied voltage to the array, with complete synchronization observed in the limit of small ramping rate. This model provides a basis for describing related nonlinear phenomena in more complex electronic structures such as semiconductor superlattices [2]. [1] A. Pikovsky, M. Rosenbaum, and Jürgen Kurths, Synchronization: a universal concept in nonlinear sciences (Cambridge University Press, Cambridge, 2001). [2] M. Rogozia, S. W. Teitsworth, H. T Grahn, and K. H. Ploog, Phys. Rev. B65, 205303 (2002).

  17. Modeling the effects of linear shallow-water internal waves on horizontal array coherence.

    PubMed

    Rouseff, Daniel; Lunkov, Andrey A

    2015-10-01

    The coherence length of a horizontal array is the maximum separation between two points where coherent processing gives useful gain when a distant source is at broadside. In shallow water, the coherence length is limited by the environmental variability caused by several relevant oceanographic processes. In the present study, a statistical model is developed that quantifies how one oceanographic process, linear internal waves, affects the coherence length. A key input to the ocean sub-model is the vertically integrated energy density of the internal wave field. The acoustic sub-model is based on the adiabatic normal mode approximation and so should be reasonable for frequencies under 1 kHz. Numerical calculations using environmental data from the Shallow Water 2006 Experiment (SW06) show how the coherence length of individual modes varies with consequent effects on array coherence. The coherence length is shown to be a strong function of where the source and array are positioned in the water column. For a bottom-mounted array above a moderately lossy seabed, the model predicts a coherence length that depends only weakly on range, an effect observed in field experiments.

  18. Flexible, phase-matched, linear receive arrays for high-field MRI in monkeys.

    PubMed

    Goense, Jozien; Logothetis, Nikos K; Merkle, Hellmut

    2010-10-01

    High signal-to-noise ratios (SNR) are essential for high-resolution anatomical and functional MRI. Phased arrays are advantageous for this but have the drawback that they often have inflexible and bulky configurations. Particularly in experiments where functional MRI is combined with simultaneous electrophysiology, space constraints can be prohibitive. To this end we developed a highly flexible multiple receive element phased array for use on anesthetized monkeys. The elements are interchangeable and different sizes and combinations of coil elements can be used, for instance, combinations of single and overlapped elements. The preamplifiers including control electronics are detachable and can serve a variety of prefabricated and phase matched arrays of different configurations, allowing the elements to always be placed in close proximity to the area of interest. Optimizing performance of the individual elements ensured high SNR at the cortical surface as well as in deeper laying structures. Performance of a variety of arrangements of gapped linear arrays was evaluated at 4.7 and 7T in high-resolution anatomical and functional MRI.

  19. Angle resolution of wideband signals received by two slightly diverse linear antenna arrays

    NASA Astrophysics Data System (ADS)

    Bagdasaryan, S. T.; Zinevich, Y. P.

    1984-05-01

    The problem of angle resolution is considered in the case of detection of wideband signals by means of antenna arrays with a discontinuous aperture. The receiver antenna is assumed to be linear and to consist of two separate equidistant arrays of weakly directional elements. The signals are assumed to appear at the receiver on plane electromagnetic waves together with interference and intrinsic noise, both centered stationary Gaussian random processes. Expressions are derived for the energy utilization factor, characterizing the signal to noise interference ratio relative to the signal noise ratio without interference. A comparison of that energy utilization factor corresponding to optimal processing of a narrow band signal and to nonoptimal processing of a wideband signal, respectively, yields the dependence of detectability and angle resolution on the signal bandwidth and the angular spacing of signal sources.

  20. Coherent-weighted three-dimensional image reconstruction in linear-array-based photoacoustic tomography

    PubMed Central

    Wang, Depeng; Wang, Yuehang; Zhou, Yang; Lovell, Jonathan F.; Xia, Jun

    2016-01-01

    While the majority of photoacoustic imaging systems used custom-made transducer arrays, commercially-available linear transducer arrays hold the benefits of affordable price, handheld convenience and wide clinical recognition. They are not widely used in photoacoustic imaging primarily because of the poor elevation resolution. Here, without modifying the imaging geometry and system, we propose addressing this limitation purely through image reconstruction. Our approach is based on the integration of two advanced image reconstruction techniques: focal-line-based three-dimensional image reconstruction and coherent weighting. We first numerically validated our approach through simulation and then experimentally tested it in phantom and in vivo. Both simulation and experimental results proved that the method can significantly improve the elevation resolution (up to 4 times in our experiment) and enhance object contrast. PMID:27231634

  1. Coherent-weighted three-dimensional image reconstruction in linear-array-based photoacoustic tomography.

    PubMed

    Wang, Depeng; Wang, Yuehang; Zhou, Yang; Lovell, Jonathan F; Xia, Jun

    2016-05-01

    While the majority of photoacoustic imaging systems used custom-made transducer arrays, commercially-available linear transducer arrays hold the benefits of affordable price, handheld convenience and wide clinical recognition. They are not widely used in photoacoustic imaging primarily because of the poor elevation resolution. Here, without modifying the imaging geometry and system, we propose addressing this limitation purely through image reconstruction. Our approach is based on the integration of two advanced image reconstruction techniques: focal-line-based three-dimensional image reconstruction and coherent weighting. We first numerically validated our approach through simulation and then experimentally tested it in phantom and in vivo. Both simulation and experimental results proved that the method can significantly improve the elevation resolution (up to 4 times in our experiment) and enhance object contrast.

  2. High-frequency (>50 MHz) medical ultrasound linear arrays fabricated from micromachined bulk PZT materials.

    PubMed

    Liu, Changgeng; Zhou, Qifa; Djuth, Frank T; Shung, K Kirk

    2012-02-01

    This paper describes the development and characterization of a high-frequency (65-MHz) ultrasound transducer linear array. The array was built from bulk PZT which was etched using an optimized chlorine-based plasma dry-etching process. The median etch rate of 8 µ m/h yielded a good profile (wall) angle (>83°) and a reasonable processing time for etch depths up to 40 μm (which corresponds to a 50-MHz transducer). A backing layer with an acoustic impedance of 6 MRayl and a front-end polymer matching layer yielded a transducer bandwidth of 40%. The major parameters of the transducer have been characterized. The two-way insertion loss and crosstalk between adjacent channels at the center frequency are 26.5 and -25 dB, respectively.

  3. Digital radiography of the chest by self-scanning linear diode arrays.

    PubMed

    Slasky, B S; Sashin, D; Horton, J A; Sternglass, E J; Bron, K M; Deutsch, M; Herron, J M; Kennedy, W H; Boyer, J W; Girdany, B R

    1987-01-01

    Diode array digital radiography DADR is a method of radiographic imaging that combines the advantages of computer technology with self-scanning linear diode arrays. These digital images are superior to those obtained by film in recording and displaying information in the lightest and the darkest areas of the film, resulting in a balanced image of the entire thorax without compromising detail, and at reduced radiation dose. This is a direct result of the wide dynamic range, high contrast sensitivity, fiber optic coupling, small diode size, short exposure time, and rejection of scattered x-rays of the system coupled with digital post-processing enhancement of the image displayed at 1024 X 1024 pixels.

  4. Angle-Polarization Estimation for Coherent Sources with Linear Tripole Sensor Arrays

    PubMed Central

    Wang, Kun; He, Jin; Shu, Ting; Liu, Zhong

    2016-01-01

    We propose a parallel factor (PARAFAC) analysis-based angle and polarization estimation algorithm for multiple coherent sources using a uniformly-spaced linear tripole sensor array. By forming a PARAFAC model using the spatial signature of the tripole array, the new algorithm requires neither spatial smoothing nor vector-field smoothing to decorrelate the signal coherency. We also establish that the angle-polarization parameters of K coherent signals can be uniquely determined by PARAFAC analysis, as long as the number of tripoles L≥2K−1. In addition, the proposed algorithm can offer enhanced angle and polarization estimation accuracy by extending the interspacing of the tripoles beyond a half wavelength. PMID:26907273

  5. High-Frequency (>50 MHz) Medical Ultrasound Linear Arrays Fabricated From Micromachined Bulk PZT Materials

    PubMed Central

    Liu, Changgeng; Zhou, Qifa; Djuth, Frank T.; Shung, K. Kirk

    2012-01-01

    This paper describes the development and characterization of a high-frequency (65-MHz) ultrasound transducer linear array. The array was built from bulk PZT which was etched using an optimized chlorine-based plasma dry-etching process. The median etch rate of 8 μm/h yielded a good profile (wall) angle (>83°) and a reasonable processing time for etch depths up to 40 μm (which corresponds to a 50-MHz transducer). A backing layer with an acoustic impedance of 6 MRayl and a front-end polymer matching layer yielded a transducer bandwidth of 40%. The major parameters of the transducer have been characterized. The two-way insertion loss and crosstalk between adjacent channels at the center frequency are 26.5 and −25 dB, respectively. PMID:24626041

  6. Analysis of upper and lower bounds of the frame noise in linear detector arrays

    NASA Technical Reports Server (NTRS)

    Jaggi, S.

    1991-01-01

    This paper estimates the upper and lower bounds of the frame noise of a linear detector array that uses a one-dimensional scan pattern. Using chi-square distribution, it is analytically shown why it is necessary to use the average of the variances and not the average of the standard deviations to estimate these bounds. Also, a criteria for determining whether any excessively noisy lines exist among the detectors is derived from these bounds. Using a Gaussian standard random variable generator, these bounds are demonstrated to be accurate within the specified confidence interval. A silicon detector array is then used for actual dark current measurements. The criterion developed for determination of noisy detectors is checked on the experimentally obtained data.

  7. Numerical and experimental simulation of linear shear piezoelectric phased arrays for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Wang, Wentao; Zhang, Hui; Lynch, Jerome P.; Cesnik, Carlos E. S.; Li, Hui

    2017-04-01

    A novel d36-type piezoelectric wafer fabricated from lead magnesium niobate-lead titanate (PMN-PT) is explored for the generation of in-plane horizontal shear waves in plate structures. The study focuses on the development of a linear phased array (PA) of PMN-PT wafers to improve the damage detection capabilities of a structural health monitoring (SHM) system. An attractive property of in-plane horizontal shear waves is that they are nondispersive yet sensitive to damage. This study characterizes the directionality of body waves (Lamb and horizontal shear) created by a single PMN-PT wafer bonded to the surface of a metallic plate structure. Second, a linear PA is designed from PMN-PT wafers to steer and focus Lamb and horizontal shear waves in a plate structure. Numerical studies are conducted to explore the capabilities of a PMN-PT-based PA to detect damage in aluminum plates. Numerical simulations are conducted using the Local Interaction Simulation Approach (LISA) implemented on a parallelized graphical processing unit (GPU) for high-speed execution. Numerical studies are further validated using experimental tests conducted with a linear PA. The study confirms the ability of an PMN-PT phased array to accurately detect and localize damage in aluminum plates.

  8. Mixed Linear/Square-Root Encoded Single Slope Ramp Provides a Fast, Low Noise Analog to Digital Converter with Very High Linearity for Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Wrigley, Christopher James (Inventor); Hancock, Bruce R. (Inventor); Newton, Kenneth W. (Inventor); Cunningham, Thomas J. (Inventor)

    2014-01-01

    An analog-to-digital converter (ADC) converts pixel voltages from a CMOS image into a digital output. A voltage ramp generator generates a voltage ramp that has a linear first portion and a non-linear second portion. A digital output generator generates a digital output based on the voltage ramp, the pixel voltages, and comparator output from an array of comparators that compare the voltage ramp to the pixel voltages. A return lookup table linearizes the digital output values.

  9. Solar cells incorporating light harvesting arrays

    DOEpatents

    Lindsey, Jonathan S.; Meyer, Gerald J.

    2003-07-22

    A solar cell incorporates a light harvesting array that comprises: (a) a first substrate comprising a first electrode; and (b) a layer of light harvesting rods electrically coupled to the first electrode, each of the light harvesting rods comprising a polymer of Formula I: ##EQU1## wherein m is at least 1, and may be from two, three or four to 20 or more; X.sup.1 is a charge separation group (and preferably a porphyrinic macrocycle, which may be one ligand of a double-decker sandwich compound) having an excited-state of energy equal to or lower than that of X.sup.2 ; and X.sup.2 through X.sup.m+1 are chromophores (and again are preferably porphyrinic macrocycles).

  10. Solar cells incorporating light harvesting arrays

    DOEpatents

    Lindsey, Jonathan S.; Meyer, Gerald J.

    2002-01-01

    A solar cell incorporates a light harvesting array that comprises: (a) a first substrate comprising a first electrode; and (b) a layer of light harvesting rods electrically coupled to the first electrode, each of the light harvesting rods comprising a polymer of Formula I: X.sup.1.paren open-st.X.sup.m+1).sub.m (I) wherein m is at least 1, and may be from two, three or four to 20 or more; X.sup.1 is a charge separation group (and preferably a porphyrinic macrocycle, which may be one ligand of a double-decker sandwich compound) having an excited-state of energy equal to or lower than that of X.sup.2 ; and X.sup.2 through X.sup.m+1 are chromophores (and again are preferably porphyrinic macrocycles).

  11. NDT and SHM of Carbon Fiber Composites using Linear Drive MWM-Arrays

    NASA Technical Reports Server (NTRS)

    Washabaugh, Andrew; Martin, Christopher; Lyons, Robert; Grundy, David; Goldfine, Neil; Russell, Richard; Wincheski, Russell

    2012-01-01

    Carbon fiber composites are used in a wide range of structural applications due to their excellent specific strength and stiffness. However, the anisotropic mechanical and electrical properties associated with the fibers within each composite layer present challenges, and opportunities, for Nondestructive Testing (NDT) methods used to characterize and assess the structure condition. This includes composite condition after manufacture (such as fiber orientation and density, porosity, delamination, and bond strength) and during usage (such as damage from impact, fiber breakage, thermal exposure or applied stress). Ultrasonic and thermographic methods can address some of these challenges, but eddy current methods provide an alternative method for composite structures that contain a conducting material, such as carbon fibers or a metallic liner. This presentation reviews recent advances in the development of eddy current sensors and arrays for carbon fiber composite NDT and Structural Health Monitoring (SHM) applications. The focus is on eddy current sensor constructs with linear drive windings, such as MWM -Arrays, that induce currents primarily within the linear fibers of the composite. By combining this type of sensor construct with micromechanical models that relate composite constituent properties to measurable sensor responses, insight is obtained into the volumetric distribution of electrical properties within the composite and the associated manufacturing, damage, or strain conditions. With knowledge of the fiber layup, this MWM-Array technology is able to detect damage and strain/stress as a function of depth and fiber orientation. This work has been funded by NASA, NA V AIR and the Army for applications ranging from composite overwrapped pressure vessels (COPVs) to aircraft structures and rotorcraft blades. This presentation will specifically present background on the MWM-Array technology, results from the micromechanical modeling effort, and results from

  12. Comparison of Hybribio GenoArray and Roche human papillomavirus (HPV) linear array for HPV genotyping in anal swab samples.

    PubMed

    Low, Huey Chi; Silver, Michelle I; Brown, Brandon J; Leng, Chan Yoon; Blas, Magaly M; Gravitt, Patti E; Woo, Yin Ling

    2015-02-01

    Human papillomavirus (HPV) is causally associated with anal cancer, as HPV DNA is detected in up to 90% of anal intraepithelial neoplasias and anal cancers. With the gradual increase of anal cancer rates, there is a growing need to establish reliable and clinically relevant methods to detect anal cancer precursors. In resource-limited settings, HPV DNA detection is a potentially relevant tool for anal cancer screening. Here, we evaluated the performance of the Hybribio GenoArray (GA) for genotyping HPV in anal samples, against the reference standard Roche Linear Array (LA). Anal swab samples were obtained from sexually active men who have sex with men. Following DNA extraction, each sample was genotyped using GA and LA. The overall interassay agreement, type-specific, and single and multiple genotype agreements were evaluated by kappa statistics and McNemar's χ(2) tests. Using GA and LA, 68% and 76% of samples were HPV DNA positive, respectively. There was substantial interassay agreements for the detection of all HPV genotypes (κ = 0.70, 86% agreement). Although LA was able to detect more genotypes per sample, the interassay agreement was acceptable (κ = 0.53, 63% agreement). GA had poorer specific detection of HPV genotypes 35, 42, and 51 (κ < 0.60). In conclusion, GA and LA showed good interassay agreement for the detection of most HPV genotypes in anal samples. However, the detection of HPV DNA in up to 76% of anal samples warrants further evaluation of its clinical significance. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  13. Application of linear array imaging techniques to the real-time inspection of airframe structures and substructures

    NASA Technical Reports Server (NTRS)

    Miller, James G.

    1995-01-01

    Development and application of linear array imaging technologies to address specific aging-aircraft inspection issues is described. Real-time video-taped images were obtained from an unmodified commercial linear-array medical scanner of specimens constructed to simulate typical types of flaws encountered in the inspection of aircraft structures. Results suggest that information regarding the characteristics, location, and interface properties of specific types of flaws in materials and structures may be obtained from the images acquired with a linear array. Furthermore, linear array imaging may offer the advantage of being able to compare 'good' regions with 'flawed' regions simultaneously, and in real time. Real-time imaging permits the inspector to obtain image information from various views and provides the opportunity for observing the effects of introducing specific interventions. Observation of an image in real-time can offer the operator the ability to 'interact' with the inspection process, thus providing new capabilities, and perhaps, new approaches to nondestructive inspections.

  14. A simple device to couple linear array transducers to neonate heads for ultrasonic scanning of the brain.

    PubMed

    Smith, W L; Franklin, T D; Katakura, K; Patrick, J T; Fry, F J; Eggleton, R C

    1980-12-01

    A plastisol coupler has been designed that improves acoustical coupling for linear array ultrasound transducers. This device improves both ease in scanning and image quality in real-time scanning of the infant brain.

  15. Guided torsional wave generation of a linear in-plane shear piezoelectric array in metallic pipes.

    PubMed

    Zhou, Wensong; Yuan, Fuh-Gwo; Shi, Tonglu

    2016-02-01

    Cylindrical guided waves based techniques are effective and promising tools for damage detection in long pipes. The essential operations are generation and reception of guided waves in the structures utilizing transducers. A novel in-plane shear (d36 type) PMNT wafer is proposed to generate and receive the guided wave, especially the torsional waves, in metallic pipes. In contrast to the traditional wafer, this wafer will directly introduce in-plane shear deformation when electrical field is conveniently applied through its thickness direction. A single square d36 PMNT wafer is bonded on the surface of the pipe positioned collinearly with its axis, when actuated can predominantly generate torsional (T) waves along the axial direction, circumferential shear horizontal (C-SH) waves along circumferential direction, and other complex cylindrical Lamb-like wave modes along other helical directions simultaneously. While a linear array of finite square size d36 PMNT wafers was equally spaced circumferentially, when actuated simultaneously can nearly uniform axisymmetric torsional waves generate in pipes and non-symmetric wave modes can be suppressed greatly if the number of the d36 PMNT wafer is sufficiently large. This paper first presents the working mechanism of the linear d36 PMNT array from finite element analysis (FEA) by examining the constructive and destructive displacement wavefield phenomena in metallic pipes. Furthermore, since the amplitude of the received fundamental torsional wave signal strongly depends on frequency, a series of experiments are conducted to determine the frequency tuning curve for the torsional wave mode. All results indicate the linear d36 PMNT array has potential for efficiently generating uniform torsional wavefield of the fundamental torsional wave mode, which is more effective in monitoring structural health in metallic pipes. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. A novel permalloy based magnetic single cell micro array.

    PubMed

    Liu, William; Dechev, Nikolai; Foulds, Ian G; Burke, Robert; Parameswaran, Ash; Park, Edward J

    2009-08-21

    Devices capable of automatically aligning cells onto geometrical arrays are of great interest to biomedical researchers. Such devices can facilitate the study of numerous cells while the cells remain physically separated from one another. In this way, cell arrays reduce cell-to-cell interactions while the cells are all subjected to common stimuli, which allows individual cell behaviour to be revealed. The use of arrays allows for the parallel analysis of single cells, facilitates data logging, and opens the door to the use of automated machine-based single cell analysis techniques. A novel permalloy based magnetic single cell micro array (MSCMA) is presented in this paper. The MSCMA creates an array of magnetic traps by generating magnetic flux density peaks at predefined locations. When using cells labelled with immunomagnetic labels, the cells will interact with the magnetic fields, and can be captured at the magnetic trap sites. Prototypes of the MSCMA have been successfully fabricated and tested using both fixed and live Jurkat cells (10 microm average diameter) that were labelled. The prototypes performed as predicted during experimental trials. The experimental results show that the MSCMA can randomly array up to 136 single cells per square mm. The results also show that the number of single cells captured is a function of the trap site density of the MSCMA design and the cell density in the fluid sample.

  17. Detection of foreign body using fast thermoacoustic tomography with a multielement linear transducer array

    SciTech Connect

    Nie Liming; Xing Da; Yang Diwu; Zeng Lvming; Zhou Quan

    2007-04-23

    Current imaging modalities face challenges in clinical applications due to limitations in resolution or contrast. Microwave-induced thermoacoustic imaging may provide a complementary modality for medical imaging, particularly for detecting foreign objects due to their different absorption of electromagnetic radiation at specific frequencies. A thermoacoustic tomography system with a multielement linear transducer array was developed and used to detect foreign objects in tissue. Radiography and thermoacoustic images of objects with different electromagnetic properties, including glass, sand, and iron, were compared. The authors' results demonstrate that thermoacoustic imaging has the potential to become a fast method for surgical localization of occult foreign objects.

  18. Detection of foreign body using fast thermoacoustic tomography with a multielement linear transducer array

    PubMed Central

    Nie, Liming; Xing, Da; Yang, Diwu; Zeng, Lvming; Zhou, Quan

    2013-01-01

    Current imaging modalities face challenges in clinical applications due to limitations in resolution or contrast. Microwave-induced thermoacoustic imaging may provide a complementary modality for medical imaging, particularly for detecting foreign objects due to their different absorption of electromagnetic radiation at specific frequencies. A thermoacoustic tomography system with a multielement linear transducer array was developed and used to detect foreign objects in tissue. Radiography and thermoacoustic images of objects with different electromagnetic properties, including glass, sand, and iron, were compared. The authors' results demonstrate that thermoacoustic imaging has the potential to become a fast method for surgical localization of occult foreign objects. PMID:23983276

  19. Detection of foreign body using fast thermoacoustic tomography with a multielement linear transducer array.

    PubMed

    Nie, Liming; Xing, Da; Yang, Diwu; Zeng, Lvming; Zhou, Quan

    2007-04-23

    Current imaging modalities face challenges in clinical applications due to limitations in resolution or contrast. Microwave-induced thermoacoustic imaging may provide a complementary modality for medical imaging, particularly for detecting foreign objects due to their different absorption of electromagnetic radiation at specific frequencies. A thermoacoustic tomography system with a multielement linear transducer array was developed and used to detect foreign objects in tissue. Radiography and thermoacoustic images of objects with different electromagnetic properties, including glass, sand, and iron, were compared. The authors' results demonstrate that thermoacoustic imaging has the potential to become a fast method for surgical localization of occult foreign objects.

  20. Linear Vector Quantisation and Uniform Circular Arrays based decoupled two-dimensional angle of arrival estimation

    NASA Astrophysics Data System (ADS)

    Ndaw, Joseph D.; Faye, Andre; Maïga, Amadou S.

    2017-05-01

    Artificial neural networks (ANN)-based models are efficient ways of source localisation. However very large training sets are needed to precisely estimate two-dimensional Direction of arrival (2D-DOA) with ANN models. In this paper we present a fast artificial neural network approach for 2D-DOA estimation with reduced training sets sizes. We exploit the symmetry properties of Uniform Circular Arrays (UCA) to build two different datasets for elevation and azimuth angles. Linear Vector Quantisation (LVQ) neural networks are then sequentially trained on each dataset to separately estimate elevation and azimuth angles. A multilevel training process is applied to further reduce the training sets sizes.

  1. Patterned hybrid nanohole array surfaces for cell adhesion and migration.

    PubMed

    Westcott, Nathan P; Lou, Yi; Muth, John F; Yousaf, Muhammad N

    2009-10-06

    We report the fabrication of hybrid nanohole array surfaces to study the role of the surface nanoevironment on cell adhesion and cell migration. We use polystyrene beads and reactive ion etching to control the size and the spacing between nanoholes on a tailored self-assembled monolayer inert gold surface. The arrays were characterized by scanning electron microscopy and brightfield microscopy. For cell adhesion studies, cells were seeded to these substrates to study the effect of ligand spacing on cell spreading, stress fiber formation, and focal adhesion structure and size. Finally, comparative cell migration rates were examined on the various nanohole array surfaces using time-lapse microscopy.

  2. Implementation and comparison of reconstruction algorithms for two-dimensional optoacoustic tomography using a linear array

    NASA Astrophysics Data System (ADS)

    Modgil, Dimple; La Rivière, Patrick J.

    2009-07-01

    Our goal is to compare and contrast various image reconstruction algorithms for optoacoustic tomography (OAT) assuming a finite linear aperture of the kind that arises when using a linear-array transducer. Because such transducers generally have tall, narrow elements, they are essentially insensitive to out-of-plane acoustic waves, and the usually 3-D OAT problem reduces to a 2-D problem. Algorithms developed for the 3-D problem may not perform optimally in 2-D. We have implemented and evaluated a number of previously described OAT algorithms, including an exact (in 3-D) Fourier-based algorithm and a synthetic-aperture-based algorithm. We have also implemented a 2-D algorithm developed by Norton for reflection mode tomography that has not, to the best of our knowledge, been applied to OAT before. Our simulation studies of resolution, contrast, noise properties, and signal detectability measures suggest that Norton's approach-based algorithm has the best contrast, resolution, and signal detectability.

  3. Fabrication of Linear Array and Top-Orthogonal-to-Bottom Electrode CMUT Arrays With a Sacrificial Release Process.

    PubMed

    Greenlay, Benjamin A; Zemp, Roger J

    2017-01-01

    The microfabrication processes for sacrificial-release-based capacitive micromachined ultrasound transducer arrays are provided with an emphasis on top-orthogonal-to-bottom electrode 2-D arrays. These arrays have significant promise for high-quality 3-D imaging with reduced wiring complexity compared with fully wired arrays. The protocols and best practices are outlined in significant detail along with design considerations and notes of caution for pitfalls and factors impacting yield.

  4. Fabrication of Linear Array and Top-Orthogonal-to-Bottom Electrode (TOBE) CMUT Arrays with a Sacrificial Release Process.

    PubMed

    Greenlay, Benjamin; Zemp, Roger

    2016-10-24

    The microfabrication processes for sacrificial-release based capacitive micromachined ultrasound transducer (CMUT) arrays are provided with an emphasis on top-orthogonal-to-bottom electrode (TOBE) 2D arrays. These arrays have significant promise for high-quality 3D imaging with reduced wiring complexity compared to fully-wired arrays. The protocols and best practices are outlined in significant detail along with design considerations and notes of caution for pitfalls and factors impacting yield.

  5. Multiple target three-dimensional coordinate estimation for bistatic MIMO radar with uniform linear receive array

    NASA Astrophysics Data System (ADS)

    Li, Jun; Li, Huan; Long, Libing; Liao, Guisheng; Griffiths, Hugh

    2013-12-01

    A novel scheme to achieve three-dimensional (3D) target location in bistatic radar systems is evaluated. The proposed scheme develops the additional information of the bistatic radar, that is the transmit angles, to estimate the 3D coordinates of the targets by using multiple-input multiple-output techniques with a uniform circular array on transmit and a uniform linear array on receive. The transmit azimuth, transmit elevation angles and receive cone angle of the targets are first extracted from the receive data and the 3D coordinates are then calculated on the basis of these angles. The geometric dilution of precision which is based on the root Cramer-Rao bound of the angles, is derived to evaluate the performance bound of the proposed scheme. Further, an ESPRIT based algorithm is developed to estimate the 3D coordinates of the targets. The advantages of this scheme are that the hardware of the receive array is reduced and the 3D coordinates of the targets can be estimated in the absence of the range information in bistatic radar. Simulations and analysis show that the proposed scheme has potential to achieve good performance with low-frequency radar.

  6. Two-dimensional imaging via a narrowband MIMO radar system with two perpendicular linear arrays.

    PubMed

    Wang, Dang-wei; Ma, Xiao-yan; Su, Yi

    2010-05-01

    This paper presents a system model and method for the 2-D imaging application via a narrowband multiple-input multiple-output (MIMO) radar system with two perpendicular linear arrays. Furthermore, the imaging formulation for our method is developed through a Fourier integral processing, and the parameters of antenna array including the cross-range resolution, required size, and sampling interval are also examined. Different from the spatial sequential procedure sampling the scattered echoes during multiple snapshot illuminations in inverse synthetic aperture radar (ISAR) imaging, the proposed method utilizes a spatial parallel procedure to sample the scattered echoes during a single snapshot illumination. Consequently, the complex motion compensation in ISAR imaging can be avoided. Moreover, in our array configuration, multiple narrowband spectrum-shared waveforms coded with orthogonal polyphase sequences are employed. The mainlobes of the compressed echoes from the different filter band could be located in the same range bin, and thus, the range alignment in classical ISAR imaging is not necessary. Numerical simulations based on synthetic data are provided for testing our proposed method.

  7. First Experiments with Planar Wire Arrays on U Michigan's Linear Transformer Driver

    NASA Astrophysics Data System (ADS)

    Safronova, A. S.; Kantsyrev, V. L.; Weller, M. E.; Shrestha, I. K.; Shlyaptseva, V. V.; Cooper, M. C.; Lorance, M.; Stafford, A.; Patel, S. G.; Steiner, A. M.; Yager-Elorriaga, D. A.; Jordan, N. M.; Gilgenbach, R. M.

    2014-10-01

    For petawatt-class Z-pinch accelerators, a Linear Transformer Driver (LTD)-driven accelerator promises to be (at a given pinch current and implosion time) more efficient than the conventionally used Marx-driven accelerator. Because there exists almost no data on how wire arrays radiate on LTD-based machines in the USA, it is very important to perform radiation and plasma physics studies on this new type of generator. We report on the first outcome of the new partnership with University of Michigan (UM), which resulted in successful UNR-UM experiments on the low-impedance MAIZE generator with planar wire arrays (PWA). PWA is a novel wire array load that was introduced and tested in detail on high-impedance Zebra at UNR during the last years and found to be the most efficient radiator. Implosion of Al Double PWAs of different configurations were achieved on MAIZE, observed with a set of various diagnostics which include x-ray diode detectors, x-ray spectroscopy and imaging, and shadowgraphy. Al and Mg plasmas of more than 450 eV were studied in detail. Research supported by NNSA under DOE Cooperative Agreement DE-NA0001984. S. G. Patel and A. M. Steiner supported by Sandia National Laboratories. D. A. Yager-Elorriaga supported by NSF GF.

  8. Linear and nonlinear evolution of azimuthal clumping instabilities in a Z-pinch wire array

    SciTech Connect

    Tang, Wilkin; Strickler, T. S.; Lau, Y. Y.; Gilgenbach, R. M.; Zier, Jacob; Gomez, M. R.; Yu, Edmund; Garasi, Chris; Cuneo, M. E.; Mehlhorn, T. A.

    2007-01-15

    This paper presents an analytic theory on the linear and nonlinear evolution of the most unstable azimuthal clumping mode, known as the pi-mode, in a discrete wire array. In the pi-mode, neighboring wires of the array pair-up as a result of the mutual attraction of the wires which carry current in the same direction. The analytic solution displays two regimes, where the collective interactions of all wires dominate, versus where the interaction of the neighboring, single wire dominates. This solution was corroborated by two vastly different numerical codes which were used to simulate arrays with both high wire numbers (up to 600) and low wire number (8). All solutions show that azimuthal clumping of discrete wires occurs before appreciable radial motion of the wires. Thus, absence of azimuthal clumping of wires in comparison with the wires' radial motion may imply substantial lack of wire currents. While the present theory and simulations have ignored the plasma corona and axial variations, it is argued that their effects, and the complete account of the three-dimensional feature of the pi-mode, together with a scaling study of the wire number, may be expediently simulated by using only one single wire in an annular wedge with a reflection condition imposed on the wedge's boundary.

  9. Highly efficient single cell arraying by integrating acoustophoretic cell pre-concentration and dielectrophoretic cell trapping.

    PubMed

    Kim, Soo Hyeon; Antfolk, Maria; Kobayashi, Marina; Kaneda, Shohei; Laurell, Thomas; Fujii, Teruo

    2015-11-21

    To array rare cells at the single-cell level, the volumetric throughput may become a bottleneck in the cell trapping and the subsequent single-cell analysis, since the target cells per definition commonly exist in a large sample volume after purification from the original sample. Here, we present a novel approach for high throughput single cell arraying by integrating two original microfluidic devices: an acoustofluidic chip and an electroactive microwell array. The velocity of the cells is geared down in the acoustofluidic chip while maintaining a high volume flow rate at the inlet of the microsystem, and the cells are subsequently trapped one by one into the microwell array using dielectrophoresis. The integrated system exhibited a 10 times improved sample throughput compared to trapping with the electroactive microwell array chip alone, while maintaining a highly efficient cell recovery above 90%. The results indicate that the serial integration of the acoustophoretic pre-concentration with the dielectrophoretic cell trapping drastically improves the performance of the electroactive microwell array for highly efficient single cell analysis. This simple and effective system for high throughput single cell arraying with further possible integration of additional functions, including cell sorting and downstream analysis after cell trapping, has potential for development to a highly integrated and automated platform for single-cell analysis of rare cells.

  10. Development of linear array ROIC for InGaAs detector arrays with wavelength response to 2.5 microns for NIR spectroscopy and machine vision

    NASA Astrophysics Data System (ADS)

    Malchow, Douglas S.; Brubaker, Robert M.; Hansen, Marc P.

    2008-04-01

    The design and development of a new, flexible, linear array readout integrated circuit (ROIC) for a new family of linear array detectors are described in this paper. The detector technology used is based on indium-gallium-arsenide (InGaAs) and includes low dark current versions with room temperature wavelength response cutoff of 1.7 microns and versions with altered stoichiometry to shift the room temperature absorbance cutoff wavelength to 2.55 microns. Discussion includes choice of features to cover many applications, testing methods, and evaluation of the first versions produced. The result will be a highly flexible linear array family, with versions matched to biological imaging, hot process inspection, pharmaceutical pill inspection, agricultural sorting and contaminant rejection, plastics recycling, moisture monitoring of continuous web processes.

  11. Development of a 64 channel ultrasonic high frequency linear array imaging system

    PubMed Central

    Hu, ChangHong; Zhang, Lequan; Cannata, Jonathan M.; Yen, Jesse; Shung, K. Kirk

    2011-01-01

    In order to improve the lateral resolution and extend the field of view of a previously reported 48 element 30 MHz ultrasound linear array and 16-channel digital imaging system, the development of a 256 element 30 MHz linear array and an ultrasound imaging system with increased channel count has been undertaken. This paper reports the design and testing of a 64 channel digital imaging system which consists of an analog front-end pulser/receiver, 64 channels of Time-Gain Compensation (TGC), 64 channels of high-speed digitizer as well as a beamformer. A Personal Computer (PC) is used as the user interface to display real-time images. This system is designed as a platform for the purpose of testing the performance of high frequency linear arrays that have been developed in house. Therefore conventional approaches were taken it its implementation. Flexibility and ease of use are of primary concern whereas consideration of cost-effectiveness and novelty in design are only secondary. Even so, there are many issues at higher frequencies but do not exist at lower frequencies need to be solved. The system provides 64 channels of excitation pulsers while receiving simultaneously at a 20 MHz–120 MHz sampling rate to 12-bits. The digitized data from all channels are first fed through Field Programmable Gate Arrays (FPGAs), and then stored in memories. These raw data are accessed by the beamforming processor to re-build the image or to be downloaded to the PC for further processing. The beamformer that applies delays to the echoes of each channel is implemented with the strategy that combines coarse (8.3ns) and fine delays (2 ns). The coarse delays are integer multiples of the sampling clock rate and are achieved by controlling the write enable pin of the First-In-First-Out (FIFO) memory to obtain valid beamforming data. The fine delays are accomplished with interpolation filters. This system is capable of achieving a maximum frame rate of 50 frames per second. Wire phantom

  12. Development of a 64 channel ultrasonic high frequency linear array imaging system.

    PubMed

    Hu, ChangHong; Zhang, Lequan; Cannata, Jonathan M; Yen, Jesse; Shung, K Kirk

    2011-12-01

    In order to improve the lateral resolution and extend the field of view of a previously reported 48 element 30 MHz ultrasound linear array and 16-channel digital imaging system, the development of a 256 element 30 MHz linear array and an ultrasound imaging system with increased channel count has been undertaken. This paper reports the design and testing of a 64 channel digital imaging system which consists of an analog front-end pulser/receiver, 64 channels of Time-Gain Compensation (TGC), 64 channels of high-speed digitizer as well as a beamformer. A Personal Computer (PC) is used as the user interface to display real-time images. This system is designed as a platform for the purpose of testing the performance of high frequency linear arrays that have been developed in house. Therefore conventional approaches were taken it its implementation. Flexibility and ease of use are of primary concern whereas consideration of cost-effectiveness and novelty in design are only secondary. Even so, there are many issues at higher frequencies but do not exist at lower frequencies need to be solved. The system provides 64 channels of excitation pulsers while receiving simultaneously at a 20-120 MHz sampling rate to 12-bits. The digitized data from all channels are first fed through Field Programmable Gate Arrays (FPGAs), and then stored in memories. These raw data are accessed by the beamforming processor to re-build the image or to be downloaded to the PC for further processing. The beamformer that applies delays to the echoes of each channel is implemented with the strategy that combines coarse (8.3 ns) and fine delays (2 ns). The coarse delays are integer multiples of the sampling clock rate and are achieved by controlling the write enable pin of the First-In-First-Out (FIFO) memory to obtain valid beamforming data. The fine delays are accomplished with interpolation filters. This system is capable of achieving a maximum frame rate of 50 frames per second. Wire phantom images

  13. Handheld Thermoacoustic Scanning System Based on a Linear-array Transducer.

    PubMed

    Ji, Zhong; Ding, Wenzheng; Ye, Fanghao; Lou, Cunguang

    2016-07-01

    To receive the information necessary for imaging, traditional microwave-induced thermoacoustic imaging systems (MITISs) use a type of circular-scanning mode using single or arc detectors. However, the use of MITISs for body scanning is complicated by restrictions in space and imaging time. A linear-array detector, the most widely used transducer in medical ultrasound imaging systems for body scanning, is a possible alternative to MITISs for scanning biological tissues, such as from the breast or limbs. In this paper, a handheld MITIS, based on a linear-array detector and a multiple data acquisition system, is described, and the capacity of the system is explored experimentally. First, the vertical and lateral resolution of the system is discussed. Next, real-time imaging of a moving object, obtained with an image capture rate of 20 frame/s, is described. Finally, a phantom experiment is detailed, investigating the overall imaging capability. The results show that this system achieves rapid scanning with a large field of view. The system has the obvious advantages of being handheld, not using coupled fluids, and achieving real-time imaging with a large field of view, which make this MITIS more suitable for clinical applications. © The Author(s) 2015.

  14. NOTE: Verification of intensity modulated profiles using a pixel segmented liquid-filled linear array

    NASA Astrophysics Data System (ADS)

    Pardo, J.; Roselló, J. V.; Sánchez-Doblado, F.; Gómez, F.

    2006-06-01

    A liquid isooctane (C8H18) filled ionization chamber linear array developed for radiotherapy quality assurance, consisting of 128 pixels (each of them with a 1.7 mm pitch), has been used to acquire profiles of several intensity modulated fields. The results were compared with film measurements using the γ test. The comparisons show a very good matching, even in high gradient dose regions. The volume-averaging effect of the pixels is negligible and the spatial resolution is enough to verify these regions. However, some mismatches between the detectors have been found in regions where low-energy scattered photons significantly contribute to the total dose. These differences are not very important (in fact, the measurements of both detectors are in agreement using the γ test with tolerances of 3% and 3 mm in most of those regions), and may be associated with the film energy dependence. In addition, the linear array repeatability (0.27% one standard deviation) is much better than the film one (~3%). The good repeatability, small pixel size and high spatial resolution make the detector ideal for the real time profile verification of high gradient beam profiles like those present in intensity modulated radiation therapy and radiosurgery.

  15. Calibration and linearity verification of capacitance type cryo level indicators using cryogenically multiplexed diode array

    NASA Astrophysics Data System (ADS)

    Karunanithi, R.; Jacob, Subhash; Singh Gour, Abhay Singh; Das, M.; Nadig, D. S.; Prasad, M. V. N.

    2012-06-01

    In space application the precision level measurement of cryogenic liquids in the storage tanks is done using triple redundant capacitance level sensor, for control and safety point of view. The linearity of each sensor element depends upon the cylindricity and concentricity of the internal and external electrodes. The complexity of calibrating all sensors together has been addressed by two step calibration methodology which has been developed and used for the calibration of six capacitance sensors. All calibrations are done using Liquid Nitrogen (LN2) as a cryogenic fluid. In the first step of calibration, one of the elements of Liquid Hydrogen (LH2) level sensor is calibrated using 700mm eleven point discrete diode array. Four wire method has been used for the diode array. Thus a linearity curve for a single element of LH2 is obtained. In second step of calibration, using the equation thus obtained for the above sensor, it is considered as a reference for calibrating remaining elements of the same LH2 sensor and other level sensor (either Liquid Oxygen (LOX) or LH2). The elimination of stray capacitance for the capacitance level probes has been attempted. The automatic data logging of capacitance values through GPIB is done using LabVIEW 8.5.

  16. Magnetic flux and strain effects on electron transport in a linear array of nanoscopic rings

    NASA Astrophysics Data System (ADS)

    Hedin, Eric R.; Joe, Yong S.

    2017-03-01

    Electron transport through a linear array of nanoscopic rings with six quantum dot sites per ring is investigated in the presence of an external magnetic flux producing an Aharonov-Bohm phase shift effect. A tight-binding model is employed to analytically calculate the transmission as a function of electron energy, external flux, and inter-site coupling parameters. Current vs. voltage relationships of the ring system are computed using a standard scattering theory of transport and shown to modulate between semiconductor and ohmic characteristics. System parameters are adjusted in order to study the effects of a longitudinal strain on the transmission properties of the linear multiple-ring array. Longitudinal strain is modeled with a Slater-Koster type theory and is demonstrated to affect the transmission properties primarily by narrowing the transmission bands and opening up additional bandgaps in the band structure. In addition, a universal resonant transmission condition as a function of flux is extended to show that the application of strain causes the resonant transmission peaks to converge towards one-half of a flux quantum.

  17. Linear bolometer array using a high TCR VOx-Au film

    NASA Astrophysics Data System (ADS)

    Smith, Evan M.; Ginn, James C.; Warren, Andrew P.; Long, Christopher J.; Panjwani, Deep; Peale, Robert E.; Shelton, David J.

    2014-06-01

    We present a design for a low-noise bolometer linear array based on the temperature-dependent conductivity of a VOx- Au film. Typical thin film bolometers must compromise between low resistivity to limit Johnson noise and high temperature coefficient of resistivity (TCR) to maximize responsivity. Our vanadium oxide is alloyed with a small concentration of gold by co-sputtering, which gives very low resistivity and very high TCR simultaneously. The film is fabricated on an air bridge device having high thermal conductivity and small thermal time constant optimized for 30 to 60 Hz frame rates. The linear array functions as a low-power profile sensor with a modulated bias. For 1 V bias, we predict responsivity exceeding 1200 V/W. Johnson noise dominates with predicted NEP values as low as 1.0 × 10-11 W/Hz1/2. Preliminary device testing shows film resistivity below 2.5 Ω-cm with TCR exceeding -2.0%. Preliminary measurements of NEP and D* are reported.

  18. Antibody Arrays for Quality Control of Mesenchymal Stem Cells.

    PubMed

    Nishikiori, Ryo; Watanabe, Kotaro; Kato, Koichi

    2015-08-05

    Quality control of mesenchymal stem cells is an important step before their clinical use in regenerative therapy. Among various characteristics of mesenchymal stem cells, reproducibility of population compositions should be analyzed according to characteristics, such as stem cell contents and differentiation stages. Such characterization may be possible by assessing the expression of several surface markers. Here we report our attempts to utilize antibody arrays for analyzing surface markers expressed in mesenchymal stem cell populations in a high-throughput manner. Antibody arrays were fabricated using a glass plate on which a micropatterned alkanethiol monolayer was formed. Various antibodies against surface markers including CD11b, CD31, CD44, CD45, CD51, CD73, CD90, CD105, and CD254 were covalently immobilized on the micropatterned surface in an array format to obtain an antibody array. To examine the feasibility of the array, cell binding assays were performed on the array using a mouse mesenchymal stem cell line. Our results showed that cell binding was observed on the arrayed spots with immobilized antibodies which exhibited reactivity to the cells in flow cytometry. It was further found that the density of cells attached to antibody spots was correlated to the mean fluorescent channel recorded in flow cytometry. These results demonstrate that data obtained by cell binding assays on the antibody array are comparable to those by the conventional flow cytometry, while throughput of the analysis is much higher with the antibody array-based method than flow cytometry. Accordingly, we concluded that the antibody array provides a high-throughput analytical method useful for the quality control of mesenchymal stem cells.

  19. Precisely Assembled Nanofiber Arrays as a Platform to Engineer Aligned Cell Sheets for Biofabrication.

    PubMed

    Beachley, Vince; Hepfer, R Glenn; Katsanevakis, Eleni; Zhang, Ning; Wen, Xuejun

    2014-08-07

    A hybrid cell sheet engineering approach was developed using ultra-thin nanofiber arrays to host the formation of composite nanofiber/cell sheets. It was found that confluent aligned cell sheets could grow on uniaxially-aligned and crisscrossed nanofiber arrays with extremely low fiber densities. The porosity of the nanofiber sheets was sufficient to allow aligned linear myotube formation from differentiated myoblasts on both sides of the nanofiber sheets, in spite of single-side cell seeding. The nanofiber content of the composite cell sheets is minimized to reduce the hindrance to cell migration, cell-cell contacts, mass transport, as well as the foreign body response or inflammatory response associated with the biomaterial. Even at extremely low densities, the nanofiber component significantly enhanced the stability and mechanical properties of the composite cell sheets. In addition, the aligned nanofiber arrays imparted excellent handling properties to the composite cell sheets, which allowed easy processing into more complex, thick 3D structures of higher hierarchy. Aligned nanofiber array-based composite cell sheet engineering combines several advantages of material-free cell sheet engineering and polymer scaffold-based cell sheet engineering; and it represents a new direction in aligned cell sheet engineering for a multitude of tissue engineering applications.

  20. Linear-time computation of minimal absent words using suffix array.

    PubMed

    Barton, Carl; Heliou, Alice; Mouchard, Laurent; Pissis, Solon P

    2014-12-20

    An absent word of a word y of length n is a word that does not occur in y. It is a minimal absent word if all its proper factors occur in y. Minimal absent words have been computed in genomes of organisms from all domains of life; their computation also provides a fast alternative for measuring approximation in sequence comparison. There exists an [Formula: see text]-time and [Formula: see text]-space algorithm for computing all minimal absent words on a fixed-sized alphabet based on the construction of suffix automata (Crochemore et al., 1998). No implementation of this algorithm is publicly available. There also exists an [Formula: see text]-time and [Formula: see text]-space algorithm for the same problem based on the construction of suffix arrays (Pinho et al., 2009). An implementation of this algorithm was also provided by the authors and is currently the fastest available. Our contribution in this article is twofold: first, we bridge this unpleasant gap by presenting an [Formula: see text]-time and [Formula: see text]-space algorithm for computing all minimal absent words based on the construction of suffix arrays; and second, we provide the respective implementation of this algorithm. Experimental results, using real and synthetic data, show that this implementation outperforms the one by Pinho et al. The open-source code of our implementation is freely available at http://github.com/solonas13/maw . Classical notions for sequence comparison are increasingly being replaced by other similarity measures that refer to the composition of sequences in terms of their constituent patterns. One such measure is the minimal absent words. In this article, we present a new linear-time and linear-space algorithm for the computation of minimal absent words based on the suffix array.

  1. Off-Grid Direction of Arrival Estimation Based on Joint Spatial Sparsity for Distributed Sparse Linear Arrays

    PubMed Central

    Liang, Yujie; Ying, Rendong; Lu, Zhenqi; Liu, Peilin

    2014-01-01

    In the design phase of sensor arrays during array signal processing, the estimation performance and system cost are largely determined by array aperture size. In this article, we address the problem of joint direction-of-arrival (DOA) estimation with distributed sparse linear arrays (SLAs) and propose an off-grid synchronous approach based on distributed compressed sensing to obtain larger array aperture. We focus on the complex source distribution in the practical applications and classify the sources into common and innovation parts according to whether a signal of source can impinge on all the SLAs or a specific one. For each SLA, we construct a corresponding virtual uniform linear array (ULA) to create the relationship of random linear map between the signals respectively observed by these two arrays. The signal ensembles including the common/innovation sources for different SLAs are abstracted as a joint spatial sparsity model. And we use the minimization of concatenated atomic norm via semidefinite programming to solve the problem of joint DOA estimation. Joint calculation of the signals observed by all the SLAs exploits their redundancy caused by the common sources and decreases the requirement of array size. The numerical results illustrate the advantages of the proposed approach. PMID:25420150

  2. Effects of a near-field rigid sphere scatterer on the performance of linear microphone array beamformers.

    PubMed

    Hu, Yuxiang; Zhou, Haoran; Lu, Jing; Qiu, Xiaojun

    2016-08-01

    Beamformers enable a microphone array to capture acoustic signals from a sound source with high signal to noise ratio in a noisy environment, and the linear microphone array is of particular importance, in practice, due to its simplicity and easy implementation. A linear microphone array sometimes is used near some scattering objects, which affect its beamforming performance. This paper develops a numerical model with a linear microphone array near a rigid sphere for both far-field plane wave and near-field sources. The effects of the scatterer on two typical beamformers, i.e., the delay-and-sum beamformer and the superdirective beamformer, are investigated by both simulations and experiments. It is found that the directivity factor of both beamformers improves due to the increased equivalent array aperture when the size of the array is no larger than that of the scatter. With the increase of the array size, the directivity factor tends to deteriorate at high frequencies because of the rising side-lobes. When the array size is significantly larger than that of the scatterer, the scattering has hardly any influence on the beamforming performance.

  3. Off-grid direction of arrival estimation based on joint spatial sparsity for distributed sparse linear arrays.

    PubMed

    Liang, Yujie; Ying, Rendong; Lu, Zhenqi; Liu, Peilin

    2014-11-20

    In the design phase of sensor arrays during array signal processing, the estimation performance and system cost are largely determined by array aperture size. In this article, we address the problem of joint direction-of-arrival (DOA) estimation with distributed sparse linear arrays (SLAs) and propose an off-grid synchronous approach based on distributed compressed sensing to obtain larger array aperture. We focus on the complex source distribution in the practical applications and classify the sources into common and innovation parts according to whether a signal of source can impinge on all the SLAs or a specific one. For each SLA, we construct a corresponding virtual uniform linear array (ULA) to create the relationship of random linear map between the signals respectively observed by these two arrays. The signal ensembles including the common/innovation sources for different SLAs are abstracted as a joint spatial sparsity model. And we use the minimization of concatenated atomic norm via semidefinite programming to solve the problem of joint DOA estimation. Joint calculation of the signals observed by all the SLAs exploits their redundancy caused by the common sources and decreases the requirement of array size. The numerical results illustrate the advantages of the proposed approach.

  4. Enhanced photovoltaic performance of an inclined nanowire array solar cell.

    PubMed

    Wu, Yao; Yan, Xin; Zhang, Xia; Ren, Xiaomin

    2015-11-30

    An innovative solar cell based on inclined p-i-n nanowire array is designed and analyzed. The results show that the inclined geometry can sufficiently increase the conversion efficiency of solar cells by enhancing the absorption of light in the active region. By tuning the nanowire array density, nanowire diameter, nanowire length, as well as the proportion of intrinsic region of the inclined nanowire solar cell, a remarkable efficiency in excess of 16% can be obtained in GaAs. Similar results have been obtained in InP and Si nanowire solar cells, demonstrating the universality of the performance enhancement of inclined nanowire arrays.

  5. Design Methodology of a Dual-Halbach Array Linear Actuator with Thermal-Electromagnetic Coupling.

    PubMed

    Eckert, Paulo Roberto; Flores Filho, Aly Ferreira; Perondi, Eduardo; Ferri, Jeferson; Goltz, Evandro

    2016-03-11

    This paper proposes a design methodology for linear actuators, considering thermal and electromagnetic coupling with geometrical and temperature constraints, that maximizes force density and minimizes force ripple. The method allows defining an actuator for given specifications in a step-by-step way so that requirements are met and the temperature within the device is maintained under or equal to its maximum allowed for continuous operation. According to the proposed method, the electromagnetic and thermal models are built with quasi-static parametric finite element models. The methodology was successfully applied to the design of a linear cylindrical actuator with a dual quasi-Halbach array of permanent magnets and a moving-coil. The actuator can produce an axial force of 120 N and a stroke of 80 mm. The paper also presents a comparative analysis between results obtained considering only an electromagnetic model and the thermal-electromagnetic coupled model. This comparison shows that the final designs for both cases differ significantly, especially regarding its active volume and its electrical and magnetic loading. Although in this paper the methodology was employed to design a specific actuator, its structure can be used to design a wide range of linear devices if the parametric models are adjusted for each particular actuator.

  6. Design Methodology of a Dual-Halbach Array Linear Actuator with Thermal-Electromagnetic Coupling

    PubMed Central

    Eckert, Paulo Roberto; Flores Filho, Aly Ferreira; Perondi, Eduardo; Ferri, Jeferson; Goltz, Evandro

    2016-01-01

    This paper proposes a design methodology for linear actuators, considering thermal and electromagnetic coupling with geometrical and temperature constraints, that maximizes force density and minimizes force ripple. The method allows defining an actuator for given specifications in a step-by-step way so that requirements are met and the temperature within the device is maintained under or equal to its maximum allowed for continuous operation. According to the proposed method, the electromagnetic and thermal models are built with quasi-static parametric finite element models. The methodology was successfully applied to the design of a linear cylindrical actuator with a dual quasi-Halbach array of permanent magnets and a moving-coil. The actuator can produce an axial force of 120 N and a stroke of 80 mm. The paper also presents a comparative analysis between results obtained considering only an electromagnetic model and the thermal-electromagnetic coupled model. This comparison shows that the final designs for both cases differ significantly, especially regarding its active volume and its electrical and magnetic loading. Although in this paper the methodology was employed to design a specific actuator, its structure can be used to design a wide range of linear devices if the parametric models are adjusted for each particular actuator. PMID:26978370

  7. Scaling nominal solar cell impedances for array design

    SciTech Connect

    Mueller, R.L.; Wallace, M.T.; Iles, P.

    1994-12-31

    A methodology for estimating the AC impedance of solar arrays and in particular the Mars Pathfinder (MPF) spacecraft cruise stage and lander solar arrays is presented. During an early stage in the spacecraft design, the MPF mission, cost and mass constraints resulted in a proposal to use a gallium arsenide on germanium (GaAs/Ge) cell solar array for the cruise stage and a silicon, back surface field/reflector (Si BSFR) cell solar array for the Mars lander. Previous work had shown that the AC impedance of Si BSFR cells was very different from that of GaAs/Ge cells. There was concern over how the difference in AC impedance would influence the design of the power bus voltage control circuitry and the stability of the power bus in general. The results presented in this paper are based on AC impedance measurements made on single cells and small solar cell arrays. Those measurements were then scaled to the larger spacecraft arrays. In each case, a generic AC model was used to construct impedance equations which were then correlated to test results to find the resistive and capacitive components of the cell impedance between 100 Hz and 100 Khz. The data was obtained using dark forward biasing to simulate different load points and intensities. Cell impedance tests show a large difference between Si BSFR and either Si non-BSF or GaAs/Ge cells, mainly because of the inherently high effective capacitance of the BSFR cells.

  8. Spraylon fluorocarbon encapsulation for silicon solar cell arrays

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A development program was performed for evaluating, modifying, and optimizing the Lockheed formulated liquid transparent filmforming Spraylon fluorocarbon protective coating for silicon solar cells and modules. The program objectives were designed to meet the requirements of the low-cost automated solar cell array fabrication process. As part of the study, a computer program was used to establish the limits of the safe working stress in the coated silicon solar cell array system under severe thermal shock.

  9. New Array Approaches to Explore Single Cells Genomes

    PubMed Central

    Vanneste, Evelyne; Bittman, Lilach; Van der Aa, Niels; Voet, Thierry; Vermeesch, Joris Robert

    2011-01-01

    Microarray analysis enables the genome-wide detection of copy number variations and the investigation of chromosomal instability. Whereas array techniques have been well established for the analysis of unamplified DNA derived from many cells, it has been more challenging to enable the accurate analysis of single cell genomes. In this review, we provide an overview of single cell DNA amplification techniques, the different array approaches, and discuss their potential applications to study human embryos. PMID:22509179

  10. Linear arrays of uncoolded poly SiGe microbolometers for IR detection

    NASA Astrophysics Data System (ADS)

    De Moor, Piet; Sedky, Sherif; Sabuncuoglu, Deniz; Van Hoof, Chris A.

    1999-08-01

    In this work we demonstrate the advantages of using polycrystalline silicon germanium (poly SiGe) as a structural material for surface micromachined devices, and more specifically uncooled Infra-Red (IR) microbolometers. The low stress and the low thermal conductivity of poly SiGe enable the realization of IR microbolometers having an effective detectivity above 2 X 109 cm.Hz1/2/W. Currently, linear arrays of optimized devices included in an on-chip vacuum package are developed. The vapor HF sacrificial etching technique is used to release extremely thin microbolometers with high yield. Combined with the practical advantage of an uncooled system, a low-cost yet sensitive sensor system is the result. Possible applications include space based pushbroom earth sensing, spectral environmental monitoring and process control.

  11. General linear codes for fault-tolerant matrix operations on processor arrays

    NASA Technical Reports Server (NTRS)

    Nair, V. S. S.; Abraham, J. A.

    1988-01-01

    Various checksum codes have been suggested for fault-tolerant matrix computations on processor arrays. Use of these codes is limited due to potential roundoff and overflow errors. Numerical errors may also be misconstrued as errors due to physical faults in the system. In this a set of linear codes is identified which can be used for fault-tolerant matrix operations such as matrix addition, multiplication, transposition, and LU-decomposition, with minimum numerical error. Encoding schemes are given for some of the example codes which fall under the general set of codes. With the help of experiments, a rule of thumb for the selection of a particular code for a given application is derived.

  12. Design and optimization of multi-class series-parallel linear electromagnetic array artificial muscle.

    PubMed

    Li, Jing; Ji, Zhenyu; Shi, Xuetao; You, Fusheng; Fu, Feng; Liu, Ruigang; Xia, Junying; Wang, Nan; Bai, Jing; Wang, Zhanxi; Qin, Xiansheng; Dong, Xiuzhen

    2014-01-01

    Skeletal muscle exhibiting complex and excellent precision has evolved for millions of years. Skeletal muscle has better performance and simpler structure compared with existing driving modes. Artificial muscle may be designed by analyzing and imitating properties and structure of skeletal muscle based on bionics, which has been focused on by bionic researchers, and a structure mode of linear electromagnetic array artificial muscle has been designed in this paper. Half sarcomere is the minimum unit of artificial muscle and electromagnetic model has been built. The structural parameters of artificial half sarcomere actuator were optimized to achieve better movement performance. Experimental results show that artificial half sarcomere actuator possesses great motion performance such as high response speed, great acceleration, small weight and size, robustness, etc., which presents a promising application prospect of artificial half sarcomere actuator.

  13. Fabrication and Characterization of Linear Terahertz Detector Arrays Based on Lithium Tantalate Crystal

    NASA Astrophysics Data System (ADS)

    Li, Weizhi; Wang, Jun; Gou, Jun; Huang, Zehua; Jiang, Yadong

    2015-01-01

    Two samples of 30-pixel linear terahertz detector arrays (TDAs) were fabricated based on lithium tantalate (LT) crystals. Pixel readout circuit (ROC) was designed to extract the weak current signal of TDAs. A test platform was established for performance evaluation of TDA+ROC components. By using a 2.52THz laser as radiation source, the test results reveal that average voltage responsivities of the components were larger than 7000V/W and non-uniformity no more than 2.1%. Average noise equivalent power ( NEP) of one sample was measured to be 1.5×10-9 W/Hz1/2, which is low enough and desirable for high performance THz detector.

  14. Self-assembly of linear arrays of semiconductor nanoparticles on carbon single-walled nanotubes.

    PubMed

    Engtrakul, Chaiwat; Kim, Yong-Hyun; Nedeljković, Jovan M; Ahrenkiel, S Phil; Gilbert, Katherine E H; Alleman, Jeff L; Zhang, S B; Mićić, Olga I; Nozik, Arthur J; Heben, Michael J

    2006-12-21

    Ligand-stabilized nanocrystals (NCs) were strongly bound to the nanotube surfaces by simple van der Waals forces. Linear arrays of CdSe and InP quantum dots were formed by self-assembly using the grooves in bundles of carbon single-walled nanotubes (SWNTs) as a one-dimensional template. A simple geometrical model explains the ordering in terms of the anisotropic properties of the nanotube surface. CdSe quantum rods were also observed to self-organize onto SWNTs with their long axis parallel to the nanotube axis. This approach offers a route to the formation of ordered NC/SWNT architectures that avoids problems associated with surface derivatization.

  15. Model-based Estimation for Pose, Velocity of Projectile from Stereo Linear Array Image

    NASA Astrophysics Data System (ADS)

    Zhao, Zhuxin; Wen, Gongjian; Zhang, Xing; Li, Deren

    2012-01-01

    The pose (position and attitude) and velocity of in-flight projectiles have major influence on the performance and accuracy. A cost-effective method for measuring the gun-boosted projectiles is proposed. The method adopts only one linear array image collected by the stereo vision system combining a digital line-scan camera and a mirror near the muzzle. From the projectile's stereo image, the motion parameters (pose and velocity) are acquired by using a model-based optimization algorithm. The algorithm achieves optimal estimation of the parameters by matching the stereo projection of the projectile and that of the same size 3D model. The speed and the AOA (angle of attack) could also be determined subsequently. Experiments are made to test the proposed method.

  16. A custom-made linear array transducer for photoacoustic breast imaging

    NASA Astrophysics Data System (ADS)

    Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Van Hespen, Johan; van Veldhoven, Spiridon; Prins, Christian; van Leeuwen, Ton G.; Steenbergen, Wiendelt; Manohar, Srirang

    2012-02-01

    A custom-made first prototype of a linear array ultrasound transducer for breast imaging is presented. Large active area transducer elements (5 mm × 5 mm) with 1 MHz resonance frequency are chosen to obtain a relatively high sensitivity. Acoustic lenses are used to enlarge the narrow acceptance angle of such transducer elements. The minimum detectable pressure, frequency bandwidth and electrical impedance of the transducer elements are characterized. The results show the transducer has a minimum detectable pressure of 0.8 Pa, which is superior than the transducers used in the Twente Photoacoustic Mammoscope system previously developed in our group. The bandwidth of the transducer is relative small, however it can be improved when using optimized matching layer thickness in future. We also observed a strong lateral resonance at 330 kHz, which may cause problems in various aspects for a photoacoustic imaging system. We discuss the future improvement and plans for the transducer optimizations.

  17. Digital Radiography and Computed Tomography Project -- Fully Integrated Linear Detector ArrayStatus Report

    SciTech Connect

    Tim Roney; Robert Seifert; Bob Pink; Mike Smith

    2011-09-01

    The field-portable Digital Radiography and Computed Tomography (DRCT) x-ray inspection systems developed for the Project Manager for NonStockpile Chemical Materiel (PMNSCM) over the past 13 years have used linear diode detector arrays from two manufacturers; Thomson and Thales. These two manufacturers no longer produce this type of detector. In the interest of insuring the long term viability of the portable DRCT single munitions inspection systems and to improve the imaging capabilities, this project has been investigating improved, commercially available detectors. During FY-10, detectors were evaluated and one in particular, manufactured by Detection Technologies (DT), Inc, was acquired for possible integration into the DRCT systems. The remainder of this report describes the work performed in FY-11 to complete evaluations and fully integrate the detector onto a representative DRCT platform.

  18. A novel PIN photodetector with double linear arrays for rainfall prediction

    NASA Astrophysics Data System (ADS)

    Yan, Yao; Xiong, Liu; Li, Yuan; Zhaohua, Zhang; Tianling, Ren

    2015-09-01

    A novel PIN (positive-intrinsic-negative) photodetector with double linear arrays that can be used to measure the diameter of precipitation particles and the space between two droplets in clouds is proposed. The sensitive unit is the PIN photodiode. The chip with a size of 10 × 8 mm2 has 128 photodiodes, and each row has 64 photodiodes. The device design, fabrication process and package are introduced in the paper. The photocurrent of the packaged chip was systematically tested with a red laser. Also the diameter of one water drop and the space between two water drops were measured. The minimum raindrop diameter which can be tested in this paper is 100 μm. This device can be useful for rainfall prediction. Project supported by the National Natural Science Foundation of China (No. 61434001) and the ‘Thousands Talents’ Program for Pioneer Researchers and Its Innovation Team, China.

  19. A portable X-ray apparatus with GaAs linear array

    NASA Astrophysics Data System (ADS)

    Ardashev, E. N.; Gorokhov, S. A.; Polkovnikov, M. K.; Lobanov, I. S.; Vorobiev, A. P.

    2011-08-01

    The widely growing interest to the digital diagnostics and analysis systems, that have many advantages in comparison with the traditional (film) systems, in data taking, data storing, and data transmitting, requires a new detection technology. One of the most promising system for medical radiography today is a scanning type apparatus with some linear array detectors. The constructed apparatus is a device with some semiconductor GaAs detectors as sensitive elements to form the image while scanning an object. GaAs detectors are the detectors of the direct transformation of X-ray radiation into the electrical. The present paper describes the results of the construction and testing of the portable X-ray unit for traumatic examination and orthopedic manipulation in stationer clinics and at the first aid in medicine of catastrophe.

  20. Innervation zones of fasciculating motor units: observations by a linear electrode array.

    PubMed

    Jahanmiri-Nezhad, Faezeh; Barkhaus, Paul E; Rymer, William Z; Zhou, Ping

    2015-01-01

    This study examines the innervation zone (IZ) in the biceps brachii muscle in healthy subjects and those with amyotrophic lateral sclerosis (ALS) using a 20-channel linear electromyogram (EMG) electrode array. Raster plots of individual waveform potentials were studied to estimate the motor unit IZ. While this work mainly focused on fasciculation potentials (FPs), a limited number of motor unit potentials (MUPs) from voluntary activity of 12 healthy and seven ALS subjects were also examined. Abnormal propagation of MUPs and scattered IZs were observed in fasciculating units, compared with voluntarily activated MUPs in healthy and ALS subjects. These findings can be related to muscle fiber reinnervation following motor neuron degeneration in ALS and the different origin sites of FPs compared with voluntary MUPs.

  1. Linear array of photodiodes to track a human speaker for video recording

    NASA Astrophysics Data System (ADS)

    DeTone, D.; Neal, H.; Lougheed, R.

    2012-12-01

    Communication and collaboration using stored digital media has garnered more interest by many areas of business, government and education in recent years. This is due primarily to improvements in the quality of cameras and speed of computers. An advantage of digital media is that it can serve as an effective alternative when physical interaction is not possible. Video recordings that allow for viewers to discern a presenter's facial features, lips and hand motions are more effective than videos that do not. To attain this, one must maintain a video capture in which the speaker occupies a significant portion of the captured pixels. However, camera operators are costly, and often do an imperfect job of tracking presenters in unrehearsed situations. This creates motivation for a robust, automated system that directs a video camera to follow a presenter as he or she walks anywhere in the front of a lecture hall or large conference room. Such a system is presented. The system consists of a commercial, off-the-shelf pan/tilt/zoom (PTZ) color video camera, a necklace of infrared LEDs and a linear photodiode array detector. Electronic output from the photodiode array is processed to generate the location of the LED necklace, which is worn by a human speaker. The computer controls the video camera movements to record video of the speaker. The speaker's vertical position and depth are assumed to remain relatively constant- the video camera is sent only panning (horizontal) movement commands. The LED necklace is flashed at 70Hz at a 50% duty cycle to provide noise-filtering capability. The benefit to using a photodiode array versus a standard video camera is its higher frame rate (4kHz vs. 60Hz). The higher frame rate allows for the filtering of infrared noise such as sunlight and indoor lighting-a capability absent from other tracking technologies. The system has been tested in a large lecture hall and is shown to be effective.

  2. Weapon detection using a wideband millimeter-wave linear array imaging technique

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; McMakin, Douglas L.; Collins, H. D.; Hall, Thomas E.

    1994-03-01

    A wideband millimeter-wave imaging technique has been developed by the Pacific Northwest Laboratory (PNL) for the detection of concealed weapons carried by personnel through high- security areas, such as airports. A practical airport system based on this technique should be capable of real-time image frame rate of 10 to 30 frames per second. This technique, similar to an extremely high-resolution radar system, actively probes the target with millimeter-waves and reconstructs an image from the backscattered phase and amplitude data. The primary goal of the system is the detection of weapons and the placement of the detected weapon on the body. An important additional goal is the identification of detected items, which requires a high resolution imaging technique. An experimental system has been developed at PNL which has gathered millimeter wave imagery from clothed mannequins and human beings carrying concealed weapons. This system is capable of forming images in excess of 1 meter by 2 meters at resolutions on the order of 1 cm, and is capable of scanning in less than 5 seconds. This experimental system could be enhanced to function in real time by eliminating the relatively slow mechanical scan. A sequentially switched linear array of transceiver antennas would allow real-time gathering of the imaging information, since the data would be electronically scanned in the lateral direction and electronically swept in frequency. This allows formation of a 2D image from a 1D array of transceiver antennas.

  3. Recent advances in a linear micromirror array for high-resolution projection

    NASA Astrophysics Data System (ADS)

    Picard, Francis; Doucet, Michel; Niall, Keith K.; Larouche, Carl; Savard, Maxime; Crisan, Silviu; Thibault, Simon; Jerominek, Hubert

    2004-05-01

    The visual displays of contemporary military flight simulators lack adequate definition to represent scenes in basic fast-jet fighter tasks. For example, air-to-air and air-to-ground targets are not projected with sufficient contrast and resolution for a pilot to perceive aspect, aspect rate and object detail at real world slant ranges. Simulator display geometries require the development of ultra-high resolution projectors with greater than 20 megapixel resolution at 60 Hz frame rate. A new micromirror device has been developed to address this requirement; it is able to modulate light intensity in an analog fashion with switching times shorter than 5 μs. When combined with a scanner, a laser and Schlieren optics, a linear array of these flexible micromirrors can display images composed of thousands of lines at a frame rate of 60 Hz. Recent results related to evaluation of this technology for high resolution projection are presented. Alternate operation modes for light modulation with flexible micromirrors are proposed. The related importance of controlling the residual micromirror curvature is discussed and results of experiments investigating the use of the deposition pressure to achieve such control are reported. Moreover, activities aiming at minimizing the micromirror response time and, so doing, maximizing the number of image columns per image frame are discussed. Finally, contrast measurement and estimate of the contrast limit achievable with the flexible micromirror technology are presented. All reported activities support the development of a fully addressable 2000-element micromirror array.

  4. Non-linear body wave teleseismic tomography along the TOR array

    NASA Astrophysics Data System (ADS)

    Shomali, Z. Hossein; Roberts, Roland G.

    2002-03-01

    The TOR project investigates the lithosphere-asthenosphere structure under the Tornquist Zone between Denmark and Sweden. Around 150 seismic stations (108 short-period, 28 broadband and 14 other permanent stations) were employed in a rectangular array along a 900km long by 100km wide strip across the Tornquist Zone from July 1996 to August 1997. The results obtained based on a non-linear teleseismic tomography algorithm reveal significant P -velocity variations (up to 5 per cent) along the TOR array from northern Germany to southern Sweden. Distinct lithospheric blocks are also recognized in the inversion results. Two inverse methods (singular value decomposition and a quadratic programming method) were implemented in order to investigate whether or not the lithospheric blocks and major boundaries in the inversion are required by the data or are artefacts of the inversion. According to the results, the lithosphere under northern Germany is thin but reaches to intermediate thicknesses of about 120km in the Tornquist Zone area. Farther north in the Baltic Shield, more than 200km of continental lithosphere is recognized in the model. Abrupt lateral P -velocity changes (maximum 5 per cent) are seen at both the southern and northern sides of the Tornquist Zone.

  5. FPGA-based electronics for confocal line scanners with linear detector arrays

    NASA Astrophysics Data System (ADS)

    Abeytunge, Sanjee; Toledo-Crow, Ricardo; Rajadhyaksha, Milind

    2009-02-01

    One-dimensional linear detector arrays have been used in the development of microscopes. Our confocal line scanning microscope electronics incorporate two printed circuit boards: control board and detector board. This architecture separates control electronics from detection electronics allowing us to minimize the footprint at microscope detector head. The Field Programmable Gate array (FPGA) on the control board generates timing and synchronization signals to three systems: detector board, frame grabber and galvanometric mirror scanner. The detector is kept away from its control electronics, and the clock and control signals are sent over a differential twisted-pair cable. These differential signals are translated to single ended signals and forwarded to the detector at the microscope detector head. The synchronization signals for the frame grabber are sent over a shielded cable. The control board also generates a saw tooth analog ramp to drive the galvanometric mirror scanner. The analog video output of the detector is fed into an operational amplifier where the white and the black levels are adjusted. Finally the analog video is send to the frame grabber via a shielded cable. FPGA-based electronics offer an inexpensive convenient means to control and synchronize simple line-scanning confocal microscopes.

  6. Imaging of downward-looking linear array SAR using three-dimensional spatial smoothing MUSIC algorithm

    NASA Astrophysics Data System (ADS)

    Zhang, Siqian; Kuang, Gangyao

    2014-10-01

    In this paper, a novel three-dimensional imaging algorithm of downward-looking linear array SAR is presented. To improve the resolution, multiple signal classification (MUSIC) algorithm has been used. However, since the scattering centers are always correlated in real SAR system, the estimated covariance matrix becomes singular. To address the problem, a three-dimensional spatial smoothing method is proposed in this paper to restore the singular covariance matrix to a full-rank one. The three-dimensional signal matrix can be divided into a set of orthogonal three-dimensional subspaces. The main idea of the method is based on extracting the array correlation matrix as the average of all correlation matrices from the subspaces. In addition, the spectral height of the peaks contains no information with regard to the scattering intensity of the different scattering centers, thus it is difficulty to reconstruct the backscattering information. The least square strategy is used to estimate the amplitude of the scattering center in this paper. The above results of the theoretical analysis are verified by 3-D scene simulations and experiments on real data.

  7. Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance

    NASA Astrophysics Data System (ADS)

    Pardo, J.; Franco, L.; Gómez, F.; Iglesias, A.; Pazos, A.; Pena, J.; Lobato, R.; Mosquera, J.; Pombar, M.; Sendón, J.

    2005-04-01

    A liquid isooctane (C8H18) filled ionization linear array for radiotherapy quality assurance has been designed, built and tested. The detector consists of 128 pixels, each of them with an area of 1.7 mm × 1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for high gradient beam profiles such as those present in intensity modulated radiation therapy (IMRT) and radiosurgery. As the read-out electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC. Studies concerning the collection efficiency dependence on the polarization voltage and on the dose rate have been made in order to optimize the device operation. In the first tests, we have studied dose rate and energy dependences. Dose rate dependence was found to be lower than 2.1% up to 5 Gy min-1, and energy dependence lower than 2.5% up to 20 cm depth in solid water. Output factors and penumbras for several rectangular fields have been measured with the linear array and were compared with the results obtained with a 0.125 cm3 air ionization chamber and radiographic film, respectively. Finally, we have acquired profiles for an IMRT field and for a virtual wedge. These profiles have also been compared with radiographic film measurements. All the comparisons show a good correspondence. The device has proved its capability to verify on-line therapy beams with good spatial resolution and signal-to-noise ratio.

  8. Normal and shear strain imaging using 2D deformation tracking on beam steered linear array datasets

    PubMed Central

    Xu, Haiyan; Varghese, Tomy

    2013-01-01

    Purpose: Previous publications have reported on the use of one-dimensional cross-correlation analysis with beam-steered echo signals. However, this approach fails to accurately track displacements at larger depths (>4.5 cm) due to lower signal-to-noise. In this paper, the authors present the use of adaptive parallelogram shaped two-dimensional processing blocks for deformation tracking. Methods: Beam-steered datasets were acquired using a VFX 9L4 linear array transducer operated at a 6 MHz center frequency for steered angles from −15 to 15° in increments of 1°, on both uniformly elastic and single-inclusion tissue-mimicking phantoms. Echo signals were acquired to a depth of 65 mm with the focus set at 40 mm corresponding to the center of phantom. Estimated angular displacements along and perpendicular to the beam direction are used to compute axial and lateral displacement vectors using a least-squares approach. Normal and shear strain tensor component are then estimated based on these displacement vectors. Results: Their results demonstrate that parallelogram shaped two-dimensional deformation tracking significantly improves spatial resolution (factor of 7.79 along the beam direction), signal-to-noise (5 dB improvement), and contrast-to-noise (8–14 dB improvement) associated with strain imaging using beam steering on linear array transducers. Conclusions: Parallelogram shaped two-dimensional deformation tracking is demonstrated in beam-steered radiofrequency data, enabling its use in the estimation of normal and shear strain components. PMID:23298118

  9. Thermal-independent properties of PIN-PMN-PT single-crystal linear-array ultrasonic transducers.

    PubMed

    Chen, Ruimin; Wu, Jinchuan; Ho Lam, Kwok; Yao, Liheng; Zhou, Qifa; Tian, Jian; Han, Pengdi; Shung, K Kirk

    2012-12-01

    In this paper, low-frequency 32-element linear-array ultrasonic transducers were designed and fabricated using both ternary Pb(In(1/2)Nb(1/2))-Pb(Mg(1/3)Nb(2/3))-PbTiO(3) (PIN-PMN-PT) and binary Pb(Mg(1/3)Nb(2/3))-PbTiO(3) (PMNPT) single crystals. Performance of the array transducers was characterized as a function of temperature ranging from room temperature to 160°C. It was found that the array transducers fabricated using the PIN-PMN-PT single crystal were capable of satisfactory performance at 160°C, having a -6-dB bandwidth of 66% and an insertion loss of 37 dB. The results suggest that the potential of PIN-PMN-PT linear-array ultrasonic transducers for high-temperature ultrasonic transducer applications is promising.

  10. Amorphous silicon cell array powered solar tracking apparatus

    DOEpatents

    Hanak, Joseph J.

    1985-01-01

    An array of an even number of amorphous silicon solar cells are serially connected between first and second terminals of opposite polarity. The terminals are connected to one input terminal of a DC motor whose other input terminal is connected to the mid-cell of the serial array. Vane elements are adjacent the end cells to selectively shadow one or the other of the end cells when the array is oriented from a desired attitude relative to the sun. The shadowing of one cell of a group of cells on one side of the mid-cell reduces the power of that group substantially so that full power from the group of cells on the other side of the mid-cell drives the motor to reorient the array to the desired attitude. The cell groups each have a full power output at the power rating of the motor. When the array is at the desired attitude the power output of the two groups of cells balances due to their opposite polarity so that the motor remains unpowered.

  11. Narrow multibeam satellite ground station antenna employing a linear array with a geosynchronous arc coverage of 60 deg. I - Theory

    NASA Astrophysics Data System (ADS)

    Amitay, N.; Gans, M. J.

    1982-11-01

    The feasibility of using an appropriately squinted linear scan in narrow multibeam satellite ground station antennas employing phased arrays is demonstrated. This linear scan has the potential of reducing the complexity of a narrow-beam planar array to that of a linear array. Calculations for such antennas placed at cities throughout the U.S. show that the peak beam pointing error in covering the 70 deg W to 130 deg W geosynchronous equatorial arc (GEA) is under 5/1000th of a degree. Communication at a 300 MBd rate in the 12/14 GHz band can be made feasible, for a grating lobe-free scan and 0.5 deg beamwidth antenna, by using a relatively simple time equalization.

  12. Resolution of Port/Starboard Ambiguity Using a Linear Array of Triplets and a Twin-Line Planar Array

    DTIC Science & Technology

    2016-06-01

    4]. Figure 2 Towed sonar array (adapted from [4]). Thermocline Self-Noise Near Field Far Field Tail Spreading Loss c(z) Ray Y Z X Array of Sensors...heat. This absorption is frequency-dependent and is quantified by the attenuation coefficient ( )fα′ , which varies also with temperature and...medium as shown in Figure 24, the first step is absorption . Since the absorption coefficient ( )fα is frequency-dependent, this operation must be

  13. CONTROL OF LASER RADIATION PARAMETERS: Phase filtering of the inphase mode of a linear laser array in the Talbot resonator

    NASA Astrophysics Data System (ADS)

    Kandidov, V. P.; Terekhova, Irina V.

    2003-06-01

    A technique for phase filtering of the inphase collective mode of a laser array in the Talbot resonator is developed. This technique is based on the formation of the phase distribution of the inphase mode field of the linear array with the finite number of channels close to that of the field of the infinite periodic structure. A simple scheme of the phase corrector, providing the increase in the selectivity of the inphase mode of the laser array in the Talbot resonator, is proposed. It is shown that the width of the principal maximum of the far-field intensity does not increase during the phase filtering.

  14. Microfabricated atomic vapor cell arrays for magnetic field measurements.

    PubMed

    Woetzel, S; Schultze, V; Ijsselsteijn, R; Schulz, T; Anders, S; Stolz, R; Meyer, H-G

    2011-03-01

    We describe a method for charging atomic vapor cells with cesium and buffer gas. By this, it is possible to adjust the buffer gas pressure in the cells with good accuracy. Furthermore, we present a new design of microfabricated vapor cell arrays, which combine silicon wafer based microfabrication and ultrasonic machining to achieve the arrays of thermally separated cells with 50 mm(3) volume. With cells fabricated in the outlined way, intrinsic magnetic field sensitivities down to 300 fT∕Hz(1∕2) are reached.

  15. 3D Ta/TaO x /TiO2/Ti synaptic array and linearity tuning of weight update for hardware neural network applications

    NASA Astrophysics Data System (ADS)

    Wang, I.-Ting; Chang, Chih-Cheng; Chiu, Li-Wen; Chou, Teyuh; Hou, Tuo-Hung

    2016-09-01

    The implementation of highly anticipated hardware neural networks (HNNs) hinges largely on the successful development of a low-power, high-density, and reliable analog electronic synaptic array. In this study, we demonstrate a two-layer Ta/TaO x /TiO2/Ti cross-point synaptic array that emulates the high-density three-dimensional network architecture of human brains. Excellent uniformity and reproducibility among intralayer and interlayer cells were realized. Moreover, at least 50 analog synaptic weight states could be precisely controlled with minimal drifting during a cycling endurance test of 5000 training pulses at an operating voltage of 3 V. We also propose a new state-independent bipolar-pulse-training scheme to improve the linearity of weight updates. The improved linearity considerably enhances the fault tolerance of HNNs, thus improving the training accuracy.

  16. Preliminary results from a novel CdZnTe linear pad detector array x-ray imaging system

    SciTech Connect

    Peng, J.; Tuemer, T.O.; Petrini, B.M.; Kravis, S.D.; Yin, S.; Parnham, K.B.; Glick, B.; Willson, P.D.

    1996-12-31

    The excellent energy-resolution and short charge collection time, especially the possibility of room temperature operation, make CdZnTe semiconductor detectors an excellent candidate for x-ray imaging and spectroscopic application in nuclear physics. Because of these characteristics, CdZnTe pad detectors with a novel geometry and approximately 1 mm{sup 2} pad area have been developed. These pad type linear arrays are new and important for many scanning type applications using a wide energy range from about 10 to 300 keV energies. A prototype x-ray imaging system has been developed consisting of a state-of-the-art pad type linear array of CdZnTe detectors manufactured by eV Products and low noise readout electronics developed by NOVA R and D, Inc. A series of measurements on the temperature dependence of the performance of CdZnTe linear pad detector arrays has been performed at NOVA R and D, Inc. The changes in dark (leakage) current against temperature have been studied. High resolution x-ray spectra has been obtained using {sup 57}Co source at different temperatures. A low noise front-end electronics ASIC chip for reading out the detector array was developed that can achieve fast data acquisition with dual energy imaging capability. Several prototype CdZnTe pad detector arrays are placed next to each other to form an approximately 30 cm long linear array. This array is used to make preliminary dual energy scanned images of complex objects using a 90 kV x-ray generator. Some of the images will be presented. The results show that the system is excellent for applications in industrial and medical imaging.

  17. Measurement of changes in linear accelerator photon energy through flatness variation using an ion chamber array

    SciTech Connect

    Gao Song; Balter, Peter A.; Rose, Mark; Simon, William E.

    2013-04-15

    Purpose: To compare the use of flatness versus percent depth dose (PDD) for determining changes in photon beam energy for a megavoltage linear accelerator. Methods: Energy changes were accomplished by adjusting the bending magnet current by up to {+-}15% in 5% increments away from the value used clinically. Two metrics for flatness, relative flatness in the central 80% of the field (Flat) and average maximum dose along the diagonals normalized by central axis dose (F{sub DN}), were measured using a commercially available planner ionization chamber array. PDD was measured in water at depths of 5 and 10 cm in 3 Multiplication-Sign 3 cm{sup 2} and 10 Multiplication-Sign 10 cm{sup 2} fields using a cylindrical chamber. Results: PDD was more sensitive to changes in energy when the beam energy was increased than when it was decreased. For the 18-MV beam in particular, PDD was not sensitive to energy reductions below the nominal energy. The value of Flat was found to be more sensitive to decreases in energy than to increases, with little sensitivity to energy increases above the nominal energy for 18-MV beams. F{sub DN} was the only metric that was found to be sensitive to both increases and reductions of energy for both the 6- and 18-MV beams. Conclusions: Flatness based metrics were found to be more sensitive to energy changes than PDD, In particular, F{sub DN} was found to be the most sensitive metric to energy changes for photon beams of 6 and 18 MV. The ionization chamber array allows this metric to be conveniently measured as part of routine accelerator quality assurance.

  18. Measurement of changes in linear accelerator photon energy through flatness variation using an ion chamber array.

    PubMed

    Gao, Song; Balter, Peter A; Rose, Mark; Simon, William E

    2013-04-01

    To compare the use of flatness versus percent depth dose (PDD) for determining changes in photon beam energy for a megavoltage linear accelerator. Energy changes were accomplished by adjusting the bending magnet current by up to ± 15% in 5% increments away from the value used clinically. Two metrics for flatness, relative flatness in the central 80% of the field (Flat) and average maximum dose along the diagonals normalized by central axis dose (FDN), were measured using a commercially available planner ionization chamber array. PDD was measured in water at depths of 5 and 10 cm in 3 × 3 cm(2) and 10 × 10 cm(2) fields using a cylindrical chamber. PDD was more sensitive to changes in energy when the beam energy was increased than when it was decreased. For the 18-MV beam in particular, PDD was not sensitive to energy reductions below the nominal energy. The value of Flat was found to be more sensitive to decreases in energy than to increases, with little sensitivity to energy increases above the nominal energy for 18-MV beams. FDN was the only metric that was found to be sensitive to both increases and reductions of energy for both the 6- and 18-MV beams. Flatness based metrics were found to be more sensitive to energy changes than PDD, In particular, FDN was found to be the most sensitive metric to energy changes for photon beams of 6 and 18 MV. The ionization chamber array allows this metric to be conveniently measured as part of routine accelerator quality assurance.

  19. Infrared line cameras based on linear arrays for industrial temperature measurement

    NASA Astrophysics Data System (ADS)

    Drogmoeller, Peter; Hofmann, Guenter; Budzier, Helmut; Reichardt, Thomas; Zimmerhackl, Manfred

    2002-03-01

    The PYROLINE/ MikroLine cameras provide continuous, non-contact measurement of linear temperature distributions. Operation in conjunction with the IR_LINE software provides data recording, real-time graphical analysis, process integration and camera-control capabilities. One system is based on pyroelectric line sensors with either 128 or 256 elements, operating at frame rates of 128 and 544 Hz respectively. Temperatures between 0 and 1300DGRC are measurable in four distinct spectral ranges; 8-14micrometers for low temperatures, 3-5micrometers for medium temperatures, 4.8-5.2micrometers for glass-temperature applications and 1.4-1.8micrometers for high temperatures. A newly developed IR-line camera (HRP 250) based upon a thermoelectrically cooled, 160-element, PbSe detector array operating in the 3 - 5 micrometers spectral range permits the thermal gradients of fast moving targets to be measured in the range 50 - 180 degree(s)C at a maximum frequency of 18kHz. This special system was used to measure temperature distributions on rotating tires at velocities of more than 300 km/h (190 mph). A modified version of this device was used for real-time measurement of disk-brake rotors under load. Another line camera consisting a 256 element InGaAs array was developed for the spectral range of 1.4 - 1.8 micrometers to detect impurities of polypropylene and polyethylene in raw cotton at frequencies of 2.5 - 5 kHz.

  20. Exploring Earth's Lowermost Mantle With Core-Diffracted Waves From Linear Arrays

    NASA Astrophysics Data System (ADS)

    Wysession, M. E.; Euler, G. G.; Fischer, K. M.

    2008-12-01

    We investigate lowermost mantle structure using the slowness and decay-rate frequency dependence of core diffracted waves from large earthquakes (mb>5.5) recorded by two broadband seismometer arrays, MOMA and FLED, to provide insights on processes occurring at the base of the mantle. MOMA (Missouri to Massachusetts) and FLED (Florida to Edmonton) were linear transects deployed in 1995-96 and 2001-02, respectively, with the common goal of obtaining seismic images of the Earth's deep interior. Exploiting core diffracted wave observables with the geometry of these arrays aids in establishing strong constraints on the radial velocity structure above the core-mantle interface in a manner analogous to surface wave observables constraining uppermost mantle structure. To estimate the frequency dependence of the slowness and decay rate caused by the diffraction process, we measure the relative arrival time and amplitude of both Pdiff and Sdiff arrivals for a series of frequency bands between 0.017 and 0.17 Hz and make corrections for bias introduced by ellipticity and velocity structure above the lowermost mantle. We present a new semi- automated technique using cluster analysis to remove low-quality waveforms and to accurately determine the slowness values. Comparison with 1D reflectivity and 3D SEM synthetics facilitates quantitative interpretation. Preliminary results confirm that there is measurable frequency dependence in the slowness and decay rate caused by diffraction for both Pdiff and Sdiff, indicative of significant radial velocity gradients. Variations in the frequency dependence are also observed with both geographic location and between Pdiff and Sdiff along the same azimuth suggesting lateral changes in Vp, Vs and Vp/Vs ratio and thus the physical state at the lowermost mantle.

  1. On the retrieval of attenuation and site amplification from ambient noise on linear arrays

    NASA Astrophysics Data System (ADS)

    Weaver, R. L.

    2012-12-01

    Retrieval of seismic velocities from arrival times in ambient noise correlations is well established. Correlation amplitudes are less well understood. Such amplitudes clearly contain information on seismic attenuation, but they are also affected by ambient noise directionality, site amplification factors, and data preprocessings. From theorems stating that noise correlations are asymptotically identifiable as Green's function times specific intensity, in turn governed by radiative transport equations, we may conclude that amplitudes are simply proportional to the usual geometric and exponential attenuation factors and also to the noise field's intensity at the pseudo-source towards the pseudo-receiver. This suggests that attenuation and site amplfication factors and noise intensity may be recoverable from observed correlation amplitudes and fit procedures well informed by theory. The above is tested by correlating the records from line arrays of six of more stations as generated by numerical simulations of wave propagation scaled to a domain of 1000 km^2, with waves of 10 second period, anisotropic noise intensity, and seismic Q's of 20 to 200. Noise correlations are examined to confirm the theoretical picture and demonstrate accurate retrieval of spatially varying attenuation, site amplification factors, and specific intensity. After correlation amplitudes are extracted from raw data records, and their variances assessed, the amplitudes are used in linear least-squares fits to retrieve propagation parameters, aposteriori error estimates, and chi-square goodnesses of fit.hirty cross-correlation amplitudes X (given by error bars) amongst six stations in a line array fit well to predictions (filled circles) based on parameters retreived by least squares. The reduced chisquare of the fit is 1.11 Site factors and attenuations between neighboring stations are recovered accurately within 0.02 nepers. Data taken from a numerical simulations of two months of ten

  2. Diamagnetically trapped arrays of living cells above micromagnets.

    PubMed

    Kauffmann, Paul; Ith, Ammara; O'Brien, Daniel; Gaude, Victor; Boué, Florian; Combe, Stéphanie; Bruckert, Franz; Schaack, Béatrice; Dempsey, Nora M; Haguet, Vincent; Reyne, Gilbert

    2011-09-21

    Cell arrays are of foremost importance for many applications in pharmaceutical research or fundamental biology. Although arraying techniques have been widely investigated for adherent cells, organization of cells in suspension has been rarely considered. The arraying of non-adherent cells using the diamagnetic repulsive force is presented. A planar arrangement of Jurkat cells is achieved at the microscale above high quality microfabricated permanent magnets with remanent magnetization of J(r)≈ 1 T, in the presence of a paramagnetic contrast agent. The cytotoxicity of three Gd based contrast agents, Gd-DOTA, Gd-BOPTA and Gd-HP-DO3A, is studied. Among them, Gd-HP-DO3A appears to be the most biocompatible toward Jurkat cells. In close agreement with analytical simulations, diamagnetically 'suspended' cells have been successfully arrayed above square and honeycomb-like micromagnet arrays, which act as a "diamagnetophobic" surface. Living cell trapping is achieved in a simple manner using concentrations of Gd-HP-DO3A as low as 1.5 mM.

  3. The feasibility of MRI-guided whole prostate ablation with a linear aperiodic intracavitary ultrasound phased array.

    PubMed

    Sokka, S D; Hynynen, K H

    2000-11-01

    Over the past decade, numerous minimally invasive thermal procedures have been investigated to treat benign prostate hyperplasia and prostate cancer. Of these methods, ultrasound has shown considerable promise due to its ability to produce more precise and deeper thermal foci. In this study, a linear, transrectal ultrasound phased array capable of ablating large tissue volumes was fabricated and evaluated. The device was designed to be compatible for use with MRI guidance and thermometry. The intracavitary applicator increases treatable tissue volume by using an ultrasonic motor to provide a mechanical rotation angle of up to 100 degrees to a 62-element 1D ultrasound array. An aperiodic array geometry was used to reduce grating lobes. In addition, a specially designed Kapton interconnect was used to reduce cable crosstalk and hence also improve the acoustic efficiency of the array. MRI-guided in vivo and ex vivo experiments were performed to verify the array's large-volume ablative capabilities. Ex vivo bovine experiments were performed to assess the focusing range of the applicator. The array generated foci in a 3 cm (2 to 5 cm from the array surface along the axis normal to the array) by 5.5 cm (along the long axis of the array) by 6 cm (along the transverse axis of the array at a depth of 4 cm) volume. In vivo rabbit thigh experiments were performed to evaluate the lesion producing capabilities in perfused tissue. The array generated 3 cm x 2 cm x 2 cm lesions with 8 to 12 half-minute sonications equally spaced in the volume. The results indicate that transrectal ultrasound coagulation of the whole prostate is feasible with the developed device.

  4. The feasibility of MRI-guided whole prostate ablation with a linear aperiodic intracavitary ultrasound phased array

    NASA Astrophysics Data System (ADS)

    Sokka, S. D.; Hynynen, K. H.

    2000-11-01

    Over the past decade, numerous minimally invasive thermal procedures have been investigated to treat benign prostate hyperplasia and prostate cancer. Of these methods, ultrasound has shown considerable promise due to its ability to produce more precise and deeper thermal foci. In this study, a linear, transrectal ultrasound phased array capable of ablating large tissue volumes was fabricated and evaluated. The device was designed to be compatible for use with MRI guidance and thermometry. The intracavitary applicator increases treatable tissue volume by using an ultrasonic motor to provide a mechanical rotation angle of up to 100° to a 62-element 1D ultrasound array. An aperiodic array geometry was used to reduce grating lobes. In addition, a specially designed Kapton interconnect was used to reduce cable crosstalk and hence also improve the acoustic efficiency of the array. MRI-guided in vivo and ex vivo experiments were performed to verify the array's large-volume ablative capabilities. Ex vivo bovine experiments were performed to assess the focusing range of the applicator. The array generated foci in a 3 cm (2 to 5 cm from the array surface along the axis normal to the array) by 5.5 cm (along the long axis of the array) by 6 cm (along the transverse axis of the array at a depth of 4 cm) volume. In vivo rabbit thigh experiments were performed to evaluate the lesion-producing capabilities in perfused tissue. The array generated 3 cm × 2 cm × 2 cm lesions with 8 to 12 half-minute sonications equally spaced in the volume. The results indicate that transrectal ultrasound coagulation of the whole prostate is feasible with the developed device.

  5. Arrayed cellular environments for stem cells and regenerative medicine.

    PubMed

    Titmarsh, Drew M; Chen, Huaying; Wolvetang, Ernst J; Cooper-White, Justin J

    2013-02-01

    The behavior and composition of both multipotent and pluripotent stem cell populations are exquisitely controlled by a complex, spatiotemporally variable interplay of physico-chemical, extracellular matrix, cell-cell interaction, and soluble factor cues that collectively define the stem cell niche. The push for stem cell-based regenerative medicine models and therapies has fuelled demands for increasingly accurate cellular environmental control and enhanced experimental throughput, driving an evolution of cell culture platforms away from conventional culture formats toward integrated systems. Arrayed cellular environments typically provide a set of discrete experimental elements with variation of one or several classes of stimuli across elements of the array. These are based on high-content/high-throughput detection, small sample volumes, and multiplexing of environments to increase experimental parameter space, and can be used to address a range of biological processes at the cell population, single-cell, or subcellular level. Arrayed cellular environments have the capability to provide an unprecedented understanding of the molecular and cellular events that underlie expansion and specification of stem cell and therapeutic cell populations, and thus generate successful regenerative medicine outcomes. This review focuses on recent key developments of arrayed cellular environments and their contribution and potential in stem cells and regenerative medicine.

  6. Automated solar-cell-array assembly machine

    NASA Technical Reports Server (NTRS)

    Costogue, E. N.; Mueller, R. L.; Person, J. K.; Yasui, R. K.

    1978-01-01

    Continuous-feeding machine automatically bonds solar cells to printed-circuit substrate. In completed machine, cells move to test station where electrical characteristics could be checked. If performance of cell is below specifications, that cell is marked and removed. All machine functions are synchronized by electronics located within unit. It may help to lower costs in future solar-cell production.

  7. Wire Array Solar Cells: Fabrication and Photoelectrochemical Studies

    NASA Astrophysics Data System (ADS)

    Spurgeon, Joshua Michael

    Despite demand for clean energy to reduce our addiction to fossil fuels, the price of these technologies relative to oil and coal has prevented their widespread implementation. Solar energy has enormous potential as a carbon-free resource but is several times the cost of coal-produced electricity, largely because photovoltaics of practical efficiency require high-quality, pure semiconductor materials. To produce current in a planar junction solar cell, an electron or hole generated deep within the material must travel all the way to the junction without recombining. Radial junction, wire array solar cells, however, have the potential to decouple the directions of light absorption and charge-carrier collection so that a semiconductor with a minority-carrier diffusion length shorter than its absorption depth (i.e., a lower quality, potentially cheaper material) can effectively produce current. The axial dimension of the wires is long enough for sufficient optical absorption while the charge-carriers are collected along the shorter radial dimension in a massively parallel array. This thesis explores the wire array solar cell design by developing potentially low-cost fabrication methods and investigating the energy-conversion properties of the arrays in photoelectrochemical cells. The concept was initially investigated with Cd(Se, Te) rod arrays; however, Si was the primary focus of wire array research because its semiconductor properties make low-quality Si an ideal candidate for improvement in a radial geometry. Fabrication routes for Si wire arrays were explored, including the vapor-liquid-solid growth of wires using SiCl4. Uniform, vertically aligned Si wires were demonstrated in a process that permits control of the wire radius, length, and spacing. A technique was developed to transfer these wire arrays into a low-cost, flexible polymer film, and grow multiple subsequent arrays using a single Si(111) substrate. Photoelectrochemical measurements on Si wire array

  8. Interventional multispectral photoacoustic imaging with a clinical linear array ultrasound probe for guiding nerve blocks

    NASA Astrophysics Data System (ADS)

    Xia, Wenfeng; West, Simeon J.; Nikitichev, Daniil I.; Ourselin, Sebastien; Beard, Paul C.; Desjardins, Adrien E.

    2016-03-01

    Accurate identification of tissue structures such as nerves and blood vessels is critically important for interventional procedures such as nerve blocks. Ultrasound imaging is widely used as a guidance modality to visualize anatomical structures in real-time. However, identification of nerves and small blood vessels can be very challenging, and accidental intra-neural or intra-vascular injections can result in significant complications. Multi-spectral photoacoustic imaging can provide high sensitivity and specificity for discriminating hemoglobin- and lipid-rich tissues. However, conventional surface-illumination-based photoacoustic systems suffer from limited sensitivity at large depths. In this study, for the first time, an interventional multispectral photoacoustic imaging (IMPA) system was used to image nerves in a swine model in vivo. Pulsed excitation light with wavelengths in the ranges of 750 - 900 nm and 1150 - 1300 nm was delivered inside the body through an optical fiber positioned within the cannula of an injection needle. Ultrasound waves were received at the tissue surface using a clinical linear array imaging probe. Co-registered B-mode ultrasound images were acquired using the same imaging probe. Nerve identification was performed using a combination of B-mode ultrasound imaging and electrical stimulation. Using a linear model, spectral-unmixing of the photoacoustic data was performed to provide image contrast for oxygenated and de-oxygenated hemoglobin, water and lipids. Good correspondence between a known nerve location and a lipid-rich region in the photoacoustic images was observed. The results indicate that IMPA is a promising modality for guiding nerve blocks and other interventional procedures. Challenges involved with clinical translation are discussed.

  9. An addressable cell array for a platform of biosensor chips

    NASA Astrophysics Data System (ADS)

    Yang, Seungkyoung; Choi, Soo-hee; Jung, Moon Youn; Song, Kibong; Park, Jeong Won

    2013-05-01

    In order to detect interested matters in fields, various lab-on-a-chips where chemical, physical, or biological sensors are loaded have been developed. eNOSE can be a representative example among them. Because animals can sense 300~1000 different chemicals by olfactory system - smell -, the olfactory system has been spotlighted as new materials in the field of sensing. Those investigations, however, are usually focused on how to detect signals from the olfactory neurons or receptors loaded on chips and enhance sensing efficacy of chips. Therefore, almost of those chips are designed for only one material sensing. Multi-sensing using multi-channels will be needed when the olfactory systems are adopted well on chips. For multiple sensing, we developed an addressable cell array. The chip has 38 cell-chambers arranged in a circle shape and different cell types of thirty eight can be allocated with specific addresses on the chip without any complex valve system. In order to confirm the cell addressing, we loaded EGFP-transfected and empty vector-transfected HEK293a cells into inlets of the cell array in a planned address and those cells were positioned into each chamber by brief aspiration. The arrayed cells were confirmed as a specific pattern through EGFP and nuclei staining. This cell array which can generate address of sensor materials like cells with their own specification is expected to be applied to a platform for a biosensor chip at various sensing fields.

  10. A Fast Method to Calculate the Spatial Impulse Response for 1-D Linear Ultrasonic Phased Array Transducers.

    PubMed

    Zou, Cheng; Sun, Zhenguo; Cai, Dong; Muhammad, Salman; Zhang, Wenzeng; Chen, Qiang

    2016-11-08

    A method is developed to accurately determine the spatial impulse response at the specifically discretized observation points in the radiated field of 1-D linear ultrasonic phased array transducers with great efficiency. In contrast, the previously adopted solutions only optimize the calculation procedure for a single rectangular transducer and required approximation considerations or nonlinear calculation. In this research, an algorithm that follows an alternative approach to expedite the calculation of the spatial impulse response of a rectangular linear array is presented. The key assumption for this algorithm is that the transducer apertures are identical and linearly distributed on an infinite rigid plane baffled with the same pitch. Two points in the observation field, which have the same position relative to two transducer apertures, share the same spatial impulse response that contributed from corresponding transducer, respectively. The observation field is discretized specifically to meet the relationship of equality. The analytical expressions of the proposed algorithm, based on the specific selection of the observation points, are derived to remove redundant calculations. In order to measure the proposed methodology, the simulation results obtained from the proposed method and the classical summation method are compared. The outcomes demonstrate that the proposed strategy can speed up the calculation procedure since it accelerates the speed-up ratio which relies upon the number of discrete points and the number of the array transducers. This development will be valuable in the development of advanced and faster linear ultrasonic phased array systems.

  11. A Fast Method to Calculate the Spatial Impulse Response for 1-D Linear Ultrasonic Phased Array Transducers

    PubMed Central

    Zou, Cheng; Sun, Zhenguo; Cai, Dong; Muhammad, Salman; Zhang, Wenzeng; Chen, Qiang

    2016-01-01

    A method is developed to accurately determine the spatial impulse response at the specifically discretized observation points in the radiated field of 1-D linear ultrasonic phased array transducers with great efficiency. In contrast, the previously adopted solutions only optimize the calculation procedure for a single rectangular transducer and required approximation considerations or nonlinear calculation. In this research, an algorithm that follows an alternative approach to expedite the calculation of the spatial impulse response of a rectangular linear array is presented. The key assumption for this algorithm is that the transducer apertures are identical and linearly distributed on an infinite rigid plane baffled with the same pitch. Two points in the observation field, which have the same position relative to two transducer apertures, share the same spatial impulse response that contributed from corresponding transducer, respectively. The observation field is discretized specifically to meet the relationship of equality. The analytical expressions of the proposed algorithm, based on the specific selection of the observation points, are derived to remove redundant calculations. In order to measure the proposed methodology, the simulation results obtained from the proposed method and the classical summation method are compared. The outcomes demonstrate that the proposed strategy can speed up the calculation procedure since it accelerates the speed-up ratio which relies upon the number of discrete points and the number of the array transducers. This development will be valuable in the development of advanced and faster linear ultrasonic phased array systems. PMID:27834799

  12. Estimation of scatterer size and acoustic concentration in sound field produced by linear phased array transducer

    NASA Astrophysics Data System (ADS)

    Oguri, Takuma; Tamura, Kazuki; Yoshida, Kenji; Mamou, Jonathan; Hasegawa, Hideyuki; Maruyama, Hitoshi; Hachiya, Hiroyuki; Yamaguchi, Tadashi

    2015-07-01

    Although there have been several quantitative ultrasound studies on the methods of estimation of scatterer size and acoustic concentration based on the analysis of RF signals for tissue characterization, some problems, e.g., narrow frequency bandwidths and complex sound fields, have limited the clinical applications of such methods. In this report, two types of ultrasound transducer are investigated for the estimation of the scatterer size and acoustic concentration in two glass bead phantoms of different weight concentrations of 0.25 and 2.50% and those in an excised pig liver. The diameters of the glass beads ranged from 5 to 63 µm with an average of 50 µm. The first transducer is a single element and the other is a linear phased array. A comparison of the estimations obtained using both transducers gives an insight into how these methods could be applied clinically. Results obtained using the two transducers were significantly different. One of the possible explanations is that beamforming could significantly affect the backscatter coefficient estimation, which was not taken into account.

  13. [HPV genotypes prevalence in México and worldwide detected by Linear Array].

    PubMed

    Flores-Miramontes, María G; Torres-Reyes, Luis A; Aguilar-Lemarroy, Adriana; Vallejo-Ruíz, Verónica; Piña-Sánchez, Patricia; Cortés-Gutiérrez, Elva; Reyes-Leyva, Julio; Jave-Suárez, Luis Felipe

    2015-01-01

    Infection with human papillomavirus (HPV) is the main factor associated with the development of cervical cancer (CC). Knowing about the prevalence of HPVs at different stages in the development of CC is important for determining the HPV oncogenic risk, the development of screening strategies, the evaluation of prevention programs, and also for vaccine designing. This paper is a meta-analysis of HPV prevalence worldwide and in Mexico from studies using the Linear Array® HPV Genotyping Test as a diagnostic test (it is the commercial test that, up to date, identifies the largest number of HPV genotypes in a single sample) in DNA of cervical samples from women with normal cytology, with low grade squamous intraepithelial lesions (LGSIL), with high grade squamous intraepithelial lesions (HGSIL) and with CC. The most prevalent genotypes after HPV-16 and -18 in women with CC varies depending on geographic region, which supports the need to develop detection and prevention strategies according to the characteristics of the population.

  14. Giant linear strain gradient with extremely low elastic energy in a perovskite nanostructure array

    PubMed Central

    Tang, Y. L.; Zhu, Y. L.; Liu, Y.; Wang, Y. J.; Ma, X. L.

    2017-01-01

    Although elastic strains, particularly inhomogeneous strains, are able to tune, enhance or create novel properties of some nanoscale functional materials, potential devices dominated by inhomogeneous strains have not been achieved so far. Here we report a fabrication of inhomogeneous strains with a linear gradient as giant as 106 per metre, featuring an extremely lower elastic energy cost compared with a uniformly strained state. The present strain gradient, resulting from the disclinations in the BiFeO3 nanostructures array grown on LaAlO3 substrates via a high deposition flux, induces a polarization of several microcoulomb per square centimetre. It leads to a large built-in electric field of several megavoltage per metre, and gives rise to a large enhancement of solar absorption. Our results indicate that it is possible to build up large-scale strain-dominated nanostructures with exotic properties, which in turn could be useful in the development of novel devices for electromechanical and photoelectric applications. PMID:28665413

  15. MLAOS: a multi-point linear array of optical sensors for coniferous foliage clumping index measurement.

    PubMed

    Qu, Yonghua; Fu, Lizhe; Han, Wenchao; Zhu, Yeqing; Wang, Jindi

    2014-05-23

    The canopy foliage clumping effect is primarily caused by the non-random distribution of canopy foliage. Currently, measurements of clumping index (CI) by handheld instruments is typically time- and labor-intensive. We propose a low-cost and low-power automatic measurement system called Multi-point Linear Array of Optical Sensors (MLAOS), which consists of three above-canopy and nine below-canopy optical sensors that capture plant transmittance at different times of the day. Data communication between the MLAOS node is facilitated by using a ZigBee network, and the data are transmitted from the field MLAOS to a remote data server using the Internet. The choice of the electronic element and design of the MLAOS software is aimed at reducing costs and power consumption. A power consumption test showed that, when a 4000 mAH Li-ion battery is used, a maximum of 8-10 months of work can be achieved. A field experiment on a coniferous forest revealed that the CI of MLAOS may reveal a clumping effect that occurs within the canopy. In further work, measurement of the multi-scale clumping effect can be achieved by utilizing a greater number of MLAOS devices to capture the heterogeneity of the plant canopy.

  16. MLAOS: A Multi-Point Linear Array of Optical Sensors for Coniferous Foliage Clumping Index Measurement

    PubMed Central

    Qu, Yonghua; Fu, Lizhe; Han, Wenchao; Zhu, Yeqing; Wang, Jindi

    2014-01-01

    The canopy foliage clumping effect is primarily caused by the non-random distribution of canopy foliage. Currently, measurements of clumping index (CI) by handheld instruments is typically time- and labor-intensive. We propose a low-cost and low-power automatic measurement system called Multi-point Linear Array of Optical Sensors (MLAOS), which consists of three above-canopy and nine below-canopy optical sensors that capture plant transmittance at different times of the day. Data communication between the MLAOS node is facilitated by using a ZigBee network, and the data are transmitted from the field MLAOS to a remote data server using the Internet. The choice of the electronic element and design of the MLAOS software is aimed at reducing costs and power consumption. A power consumption test showed that, when a 4000 mAH Li-ion battery is used, a maximum of 8–10 months of work can be achieved. A field experiment on a coniferous forest revealed that the CI of MLAOS may reveal a clumping effect that occurs within the canopy. In further work, measurement of the multi-scale clumping effect can be achieved by utilizing a greater number of MLAOS devices to capture the heterogeneity of the plant canopy. PMID:24859029

  17. Giant linear strain gradient with extremely low elastic energy in a perovskite nanostructure array

    NASA Astrophysics Data System (ADS)

    Tang, Y. L.; Zhu, Y. L.; Liu, Y.; Wang, Y. J.; Ma, X. L.

    2017-06-01

    Although elastic strains, particularly inhomogeneous strains, are able to tune, enhance or create novel properties of some nanoscale functional materials, potential devices dominated by inhomogeneous strains have not been achieved so far. Here we report a fabrication of inhomogeneous strains with a linear gradient as giant as 106 per metre, featuring an extremely lower elastic energy cost compared with a uniformly strained state. The present strain gradient, resulting from the disclinations in the BiFeO3 nanostructures array grown on LaAlO3 substrates via a high deposition flux, induces a polarization of several microcoulomb per square centimetre. It leads to a large built-in electric field of several megavoltage per metre, and gives rise to a large enhancement of solar absorption. Our results indicate that it is possible to build up large-scale strain-dominated nanostructures with exotic properties, which in turn could be useful in the development of novel devices for electromechanical and photoelectric applications.

  18. Effects of Non-Elevation-Focalized Linear Array Transducer on Ultrasound Plane-Wave Imaging

    PubMed Central

    Wang, Congzhi; Xiao, Yang; Xia, Jingjing; Qiu, Weibao; Zheng, Hairong

    2016-01-01

    Plane-wave ultrasound imaging (PWUS) has become an important method of ultrasound imaging in recent years as its frame rate has exceeded 10,000 frames per second, allowing ultrasound to be used for two-dimensional shear wave detection and functional brain imaging. However, compared to the traditional focusing and scanning method, PWUS images always suffer from a degradation of lateral resolution and contrast. To improve the image quality of PWUS, many different beamforming algorithms have been proposed and verified. Yet the influence of transducer structure is rarely studied. For this paper, the influence of using an acoustic lens for PWUS was evaluated. Two linear array transducers were fabricated. One was not self-focalized in the elevation direction (non-elevation-focalized transducer, NEFT); the other one was a traditional elevation-focalized transducer (EFT). An initial simulation was conducted to show the influence of elevation focusing. Then the images obtained with NEFT on a standard ultrasound imaging phantom were compared with those obtained with EFT. It was demonstrated that, in a relatively deep region, the contrast of an NEFT image is better than that of an EFT image. These results indicate that a more sophisticated design of ultrasound transducer would further improve the image quality of PWUS. PMID:27845751

  19. Optofluidic holographic microscopy with custom field of view (FoV) using a linear array detector.

    PubMed

    Bianco, V; Paturzo, M; Marchesano, V; Gallotta, I; Di Schiavi, E; Ferraro, P

    2015-05-07

    Simple and effective imaging strategies are of utmost interest for applications on a lab-on-chip scale. In fact, the majority of diagnostic tools for medical as well as biotechnological studies still employ image-based approaches. Having onboard the chip a compact but powerful imaging apparatus with multiple imaging capabilities, such as 3D dynamic focusing along the optical axis, unlimited field of view (FoV) and double outputs, namely, intensity and quantitative phase-contrast maps of biological objects, is of extreme importance for the next generation of Lab-on-a-Chip (LoC) devices. Here we present a coherent 3D microscopy approach with a holographic modality that is specifically suitable for studying biological samples while they simply flow along microfluidic paths. The LoC device is equipped with a compact linear array detector to capture and generate a new conceptual type of a digital hologram in the space-time domain, named here as Space-Time Digital Hologram (STDH). The reported results show that the method is a promising diagnostic tool for optofluidic investigations of biological specimens.

  20. Coexistence and limiting similarity of consumer species competing for a linear array of resources.

    PubMed

    Abrams, Peter A; Rueffler, Claus

    2009-03-01

    Consumer-resource systems with linear arrays of substitutable resources form the conceptual basis of much of present-day competition theory. However, most analyses of the limiting similarity of competitors have only employed consumer-resource models as a justification for using the Lotka-Volterra competition equations to represent the interaction. Unfortunately, Lotka-Volterra models cannot reflect resource exclusion via apparent competition and are poor approximations of systems with nonlogistic resource growth. We use consumer-resource models to examine the impact of exclusion of biotic resources or depletion of abiotic resources on the ability of three consumer species to coexist along a one-dimensional resource axis. For a wide range of consumer-resource models, coexistence conditions can become more restrictive with increasing niche separation of the two outer species. This occurs when the outer species are highly efficient; in this case they cause extinction or severe depletion of intermediate resources when their own niches have an intermediate level of separation. In many cases coexistence of an intermediate consumer species is prohibited when niche separation of the two outer species is moderately large, but not when it is small. Coexistence may be most likely when the intermediate species is closer to one of the two outer species, contrary to previous theory. These results suggest that competition may lead to uneven spacing of utilization curves. The implications and range of applicability of the models are discussed.

  1. Low-Concentration-Ratio Solar-Cell Arrays

    NASA Technical Reports Server (NTRS)

    Biss, M. S.; Reed, David A., Jr.

    1986-01-01

    Paper presents design concept for mass-producible arrays of solar electric batteries and concentrators tailored to individual requirements. Arrays intended primarily for space stations needing about 100 kW of power. However, modular, lightweight, compact, and relatively low-cost design also fulfill requirements of some terrestrial applications. Arrays built with currently available materials. Pultrusions, injectionmolded parts, and composite materials used extensively to keep weight low. For added flexibility in design and construction, silicon and gallium arsenide solar-cell panels interchangeable.

  2. Comparative evaluation of different DNA extraction methods for HPV genotyping by linear array and INNO-LiPA.

    PubMed

    Donà, Maria Gabriella; Benevolo, Maria; Pimpinelli, Fulvia; Battista, Mara; Rollo, Francesca; Stivali, Francesca; Moscarelli, Antonella; Giuliani, Massimo; Di Carlo, Aldo; Vocaturo, Amina

    2011-06-01

    In order to investigate the influence of DNA extraction on two PCR-based HPV genotyping tests (Linear Array, Roche and INNO-LiPA Extra, Innogenetics), three different procedures were used to purify DNA from 28 cervico-vaginal samples tested previously by the Hybrid Capture 2: the AmpliLute Liquid Media Extraction kit (Roche), the QIAamp DNA Blood mini kit (QIAGEN), and the NucliSENS EasyMAG automated platform (bioMérieux). All HC2-positive samples were found positive by both assays, independently of the extract used. Type-specific concordance (i.e., identical HPV type-specific profile in all the extracts of the same sample) was observed in 55% and 75% of the cases testing samples by the Linear Array and the INNO-LiPA, respectively. Using the DNA extracted with the two manual methods the results were concordant in 75% of the cases both for the Linear Array and the INNO-LiPA. When comparing the Linear Array results obtained on either of the two manual extracts with those obtained following automated extraction, 65% of the samples showed type-specific concordance in both cases. The INNO-LiPA results were concordant in 80% of the cases comparing the AmpliLute versus the automated extract, while concordant results were observed in 90% of the cases when comparing the QIAGEN versus the automated extract. In conclusion, the Linear Array and INNO-LiPA results are affected by the method of DNA extraction. Consequently, different HPV type-specific profiles may be observed using different extracts of the same sample. The use of consistent protocols for DNA purification is a priority to guarantee intra-assay reproducibility over time.

  3. The Effects of Linear Microphone Array Changes on Computed Sound Exposure Level Footprints

    NASA Technical Reports Server (NTRS)

    Mueller, Arnold W.; Wilson, Mark R.

    1997-01-01

    Airport land planning commissions often are faced with determining how much area around an airport is affected by the sound exposure levels (SELS) associated with helicopter operations. This paper presents a study of the effects changing the size and composition of a microphone array has on the computed SEL contour (ground footprint) areas used by such commissions. Descent flight acoustic data measured by a fifteen microphone array were reprocessed for five different combinations of microphones within this array. This resulted in data for six different arrays for which SEL contours were computed. The fifteen microphone array was defined as the 'baseline' array since it contained the greatest amount of data. The computations used a newly developed technique, the Acoustic Re-propagation Technique (ART), which uses parts of the NASA noise prediction program ROTONET. After the areas of the SEL contours were calculated the differences between the areas were determined. The area differences for the six arrays are presented that show a five and a three microphone array (with spacing typical of that required by the FAA FAR Part 36 noise certification procedure) compare well with the fifteen microphone array. All data were obtained from a database resulting from a joint project conducted by NASA and U.S. Army researchers at Langley and Ames Research Centers. A brief description of the joint project test design, microphone array set-up, and data reduction methodology associated with the database are discussed.

  4. Microdroplet chain array for cell migration assays.

    PubMed

    Ma, Yan; Pan, Jian-Zhang; Zhao, Shi-Ping; Lou, Qi; Zhu, Ying; Fang, Qun

    2016-11-29

    Establishing cell migration assays in multiple different microenvironments is important in the study of tissue repair and regeneration, cancer progression, atherosclerosis, and arthritis. In this work, we developed a miniaturized and massive parallel microfluidic platform for multiple cell migration assays combining the traditional membrane-based cell migration technique and the droplet-based microfluidic technique. Nanoliter-scale droplets are flexibly assembled as building blocks based on a porous membrane to form microdroplet chains with diverse configurations for different assay modes. Multiple operations including in-droplet 2D/3D cell culture, cell co-culture and cell migration induced by a chemoattractant concentration gradient in droplet chains could be flexibly performed with reagent consumption in the nanoliter range for each assay and an assay scale-up to 81 assays in parallel in one microchip. We have applied the present platform to multiple modes of cell migration assays including the accurate cell migration assay, competitive cell migration assay, biomimetic chemotaxis assay, and multifactor cell migration assay based on the organ-on-a-chip concept, for demonstrating its versatility, applicability, and potential in cell migration-related research.

  5. Selective single cell isolation for genomics using microraft arrays

    PubMed Central

    Welch, Joshua D.; Williams, Lindsay A.; DiSalvo, Matthew; Brandt, Alicia T.; Marayati, Raoud; Sims, Christopher E.; Allbritton, Nancy L.; Prins, Jan F.; Yeh, Jen Jen; Jones, Corbin D.

    2016-01-01

    Genomic methods are used increasingly to interrogate the individual cells that compose specific tissues. However, current methods for single cell isolation struggle to phenotypically differentiate specific cells in a heterogeneous population and rely primarily on the use of fluorescent markers. Many cellular phenotypes of interest are too complex to be measured by this approach, making it difficult to connect genotype and phenotype at the level of individual cells. Here we demonstrate that microraft arrays, which are arrays containing thousands of individual cell culture sites, can be used to select single cells based on a variety of phenotypes, such as cell surface markers, cell proliferation and drug response. We then show that a common genomic procedure, RNA-seq, can be readily adapted to the single cells isolated from these rafts. We show that data generated using microrafts and our modified RNA-seq protocol compared favorably with the Fluidigm C1. We then used microraft arrays to select pancreatic cancer cells that proliferate in spite of cytotoxic drug treatment. Our single cell RNA-seq data identified several expected and novel gene expression changes associated with early drug resistance. PMID:27530426

  6. A High-Frequency Linear Ultrasonic Array Utilizing an Interdigitally Bonded 2-2 Piezo-Composite

    PubMed Central

    Cannata, Jonathan M.; Williams, Jay A.; Zhang, Lequan; Hu, Chang-Hong; Shung, K. Kirk

    2011-01-01

    This paper describes the development of a high-frequency 256-element linear ultrasonic array utilizing an interdigitally bonded (IB) piezo-composite. Several IB composites were fabricated with different commercial and experimental piezoelectric ceramics and evaluated to determine a suitable formulation for use in high-frequency linear arrays. It was found that the fabricated fine-scale 2–2 IB composites outperformed 1–3 IB composites with identical pillar- and kerf-widths. This result was not expected and lead to the conclusion that dicing damage was likely the cause of the discrepancy. Ultimately, a 2–2 composite fabricated using a fine-grain piezoelectric ceramic was chosen for the array. The composite was manufactured using one IB operation in the azimuth direction to produce approximately 19-μm-wide pillars separated by 6-μm-wide kerfs. The array had a 50 μm (one wavelength in water) azimuth pitch, two matching layers, and 2 mm elevation length focused to 7.3 mm using a polymethylpentene (TPX) lens. The measured pulse-echo center frequency for a representative array element was 28 MHz and −6-dB band-width was 61%. The measured single-element transmit −6-dB directivity was estimated to be 50°. The measured insertion loss was 19 dB after compensating for the effects of attenuation and diffraction in the water bath. A fine-wire phantom was used to assess the lateral and axial resolution of the array when paired with a prototype system utilizing a 64-channel analog beamformer. The −6-dB lateral and axial resolutions were estimated to be 125 and 68 μm, respectively. An anechoic cyst phantom was also imaged to determine the minimum detectable spherical inclusion, and thus the 3-D resolution of the array and beamformer. The minimum anechoic cyst detected was approximately 300 μm in diameter. PMID:21989884

  7. Simulation and Testing of a Linear Array of Modified Four-Square Feed Antennas for the Tianlai Cylindrical Radio Telescope

    NASA Astrophysics Data System (ADS)

    Cianciara, Aleksander J.; Anderson, Christopher J.; Chen, Xuelei; Chen, Zhiping; Geng, Jingchao; Li, Jixia; Liu, Chao; Liu, Tao; Lu, Wing; Peterson, Jeffrey B.; Shi, Huli; Steffel, Catherine N.; Stebbins, Albert; Stucky, Thomas; Sun, Shijie; Timbie, Peter T.; Wang, Yougang; Wu, Fengquan; Zhang, Juyong

    A wide bandwidth, dual polarized, modified four-square antenna is presented as a feed antenna for radio astronomical measurements. A linear array of these antennas is used as a line-feed for cylindrical reflectors for Tianlai, a radio interferometer designed for 21cm intensity mapping. Simulations of the feed antenna beam patterns and scattering parameters are compared to experimental results at multiple frequencies across the 650-1420MHz range. Simulations of the beam patterns of the combined feed array/reflector are presented as well.

  8. Linear charge coupled device detector array for imaging light propagating in an integrated thin-film optical waveguide

    NASA Technical Reports Server (NTRS)

    Chen, C. L.; Boyd, J. T.

    1976-01-01

    Device design, fabrication, and operation of a linear charge coupled device (CCD) detector array integrated with a thin film optical waveguide and applications of this structure to integrated optical signal processing and fiber optical communications were discussed. A two phase, overlapping-gate CCD is connected in parallel by means of a series of gates to an array of photodiodes. The photodiode provides an electrode free surface region so that a highly efficient waveguide detector coupling technique can be implemented. A thermally-oxidized layer of SiO2 forms an effective substrate for the optical waveguide.

  9. High linearity SPAD and TDC array for TCSPC and 3D ranging applications

    NASA Astrophysics Data System (ADS)

    Villa, Federica; Lussana, Rudi; Bronzi, Danilo; Dalla Mora, Alberto; Contini, Davide; Tisa, Simone; Tosi, Alberto; Zappa, Franco

    2015-01-01

    An array of 32x32 Single-Photon Avalanche-Diodes (SPADs) and Time-to-Digital Converters (TDCs) has been fabricated in a 0.35 μm automotive-certified CMOS technology. The overall dimension of the chip is 9x9 mm2. Each pixel is able to detect photons in the 300 nm - 900 nm wavelength range with a fill-factor of 3.14% and either to count them or to time stamp their arrival time. In photon-counting mode an in-pixel 6-bit counter provides photon-numberresolved intensity movies at 100 kfps, whereas in photon-timing mode the 10-bit in-pixel TDC provides time-resolved maps (Time-Correlated Single-Photon Counting measurements) or 3D depth-resolved (through direct time-of-flight technique) images and movies, with 312 ps resolution. The photodetector is a 30 μm diameter SPAD with low Dark Count Rate (120 cps at room temperature, 3% hot-pixels) and 55% peak Photon Detection Efficiency (PDE) at 450 nm. The TDC has a 6-bit counter and a 4-bit fine interpolator, based on a Delay Locked Loop (DLL) line, which makes the TDC insensitive to process, voltage, and temperature drifts. The implemented sliding-scale technique improves linearity, giving 2% LSB DNL and 10% LSB INL. The single-shot precision is 260 ps rms, comprising SPAD, TDC and driving board jitter. Both optical and electrical crosstalk among SPADs and TDCs are negligible. 2D fast movies and 3D reconstructions with centimeter resolution are reported.

  10. Plasmonic Tipless Pyramid Arrays for Cell Poration.

    PubMed

    Courvoisier, Sébastien; Saklayen, Nabiha; Huber, Marinus; Chen, Jun; Diebold, Eric D; Bonacina, Luigi; Wolf, Jean-Pierre; Mazur, Eric

    2015-07-08

    Improving the efficiency, cell survival, and throughput of methods to modify and control the genetic expression of cells is of great benefit to biology and medicine. We investigate, both computationally and experimentally, a nanostructured substrate made of tipless pyramids for plasmonic-induced transfection. By optimizing the geometrical parameters for an excitation wavelength of 800 nm, we demonstrate a 100-fold intensity enhancement of the electric near field at the cell-substrate contact area, while the low absorption typical for gold is maintained. We demonstrate that such a substrate can induce transient poration of cells by a purely optically induced process.

  11. Evaluation of cancer cell deformability by microcavity array.

    PubMed

    Yoshino, Tomoko; Tanaka, Tsuyoshi; Nakamura, Seita; Negishi, Ryo; Shionoiri, Nozomi; Hosokawa, Masahito; Matsunaga, Tadashi

    2017-03-01

    A cell entrapment device consisting of a microcavity array was used to analyze the deformability of MCF-10 human breast epithelial and MCF-7 human breast cancer cell lines by confocal laser scanning microscopy. Entrapment of up to 8 × 10(3) cells was achieved within 3 min. Protrusions were formed at the bottom surface of the array with a pore size of 3 μm. Protrusion length increased at higher filtration pressures and could be used to distinguish between MCF-7 and MCF-10 cells. These results indicate that our system is useful for high-throughput deformability analysis of cancer cells, which can provide insight into the mechanisms underlying tumor cell malignancy.

  12. Linear-array-based photoacoustic imaging of human microcirculation with a range of high frequency transducer probes

    NASA Astrophysics Data System (ADS)

    Zafar, Haroon; Breathnach, Aedán; Subhash, Hrebesh M.; Leahy, Martin J.

    2015-05-01

    Photoacoustic imaging (PAI) with a linear-array-based probe can provide a convenient means of imaging the human microcirculation within its native structural context and adds functional information. PAI using a multielement linear transducer array combined with multichannel collecting system was used for in vivo volumetric imaging of the blood microcirculation, the total concentration of hemoglobin (HbT), and the hemoglobin oxygen saturation (sO2) within human tissue. Three-dimensional (3-D) PA and ultrasound (US) volumetric scans were acquired from the forearm skin by linearly translating the transducer with a stepper motor over a region of interest, while capturing two-dimensional images using 15, 21, and 40 MHz frequency transducer probes. For the microvasculature imaging, PA images were acquired at 800- and 1064-nm wavelengths. For the HbT and sO2 estimates, PA images were collected at 750- and 850-nm wavelengths. 3-D microcirculation, HbT, and sO2 maps of the forearm skin were obtained from normal subjects. The linear-array-based PAI has been found promising in terms of resolution, imaging depth, and imaging speed for in vivo microcirculation imaging within human skin. We believe that a reflection type probe, similar to existing clinical US probes, is most likely to succeed in real clinical applications. Its advantages include ease of use, speed, and familiarity for radiographers and clinicians.

  13. Cytotoxicity of ZnO Nanowire Arrays on Excitable Cells.

    PubMed

    Wang, Yongchen; Wu, Yu; Quadri, Farhan; Prox, Jordan D; Guo, Liang

    2017-04-07

    Zinc oxide (ZnO) nanowires have been widely studied for their applications in electronics, optics, and catalysts. Their semiconducting, piezoelectric, fluorescent, and antibacterial properties have also attracted broad interest in their biomedical applications. Thus, it is imperative to evaluate the biosafety of ZnO nanowires and their biological effects. In this study, the cellular level biological effects of ZnO nanowire arrays are specifically tested on three types of excitable cells, including NG108-15 neuronal cell line, HL-1 cardiac muscle cell line, and neonatal rat cardiomyocytes. Vertically aligned and densely packed ZnO nanowire arrays are synthesized using a solution-based method and used as a substrate for cell culture. The metabolism levels of all three types of cells cultured on ZnO nanowire arrays are studied using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays of a full factorial design. Under the studied settings, the results show statistically significant inhibitory effects of ZnO nanowire arrays on the metabolism of NG108-15 and HL-1 cells in comparison to gold, glass, and polystyrene substrates, and on the metabolism of cardiomyocytes in comparison to gold substrate.

  14. Single cell array impedance analysis in a microfluidic device

    NASA Astrophysics Data System (ADS)

    Altinagac, Emre; Taskin, Selen; Kizil, Huseyin

    2016-10-01

    Impedance analysis of single cells is presented in this paper. Following the separation of a target cell type by dielectrophoresis in our previous work, this paper focuses on capturing the cells as a single array and performing impedance analysis to point out the signature difference between each cell type. Lab-on-a-chip devices having a titanium interdigitated electrode layer on a glass substrate and a PDMS microchannel are fabricated to capture each cell in a single form and perform impedance analysis. HCT116 (homosapiens colon colorectal carcin) and HEK293 (human embryonic kidney) cells are used in our experiments.

  15. High power density fuel cell comprising an array of microchannels

    DOEpatents

    Morse, Jeffrey D.; Upadhye, Ravindra S.; Spadaccini, Christopher M.; Park, Hyung Gyu

    2013-10-15

    A fuel cell according to one embodiment includes a porous electrolyte support structure defining an array of microchannels, the microchannels including fuel and oxidant microchannels; fuel electrodes formed along some of the microchannels; and oxidant electrodes formed along other of the microchannels. A method of making a fuel cell according to one embodiment includes forming an array of walls defining microchannels therebetween using at least one of molding, stamping, extrusion, injection and electrodeposition; processing the walls to make the walls porous, thereby creating a porous electrolyte support structure; forming anode electrodes along some of the microchannels; and forming cathode electrodes along other of the microchannels. Additional embodiments are also disclosed.

  16. Thin solar cell and lightweight array

    NASA Technical Reports Server (NTRS)

    Brandhorst, Henry W., Jr. (Inventor); Weinberg, Irving (Inventor)

    1991-01-01

    A thin, lightweight solar cell that utilizes front contact metallization is presented. Both the front light receiving surface of the solar cell and the facing surface of the cover glass are recessed to accommodate this metallization. This enables the two surfaces to meet flush for an optimum seal.

  17. Cell pairing using microwell array electrodes based on dielectrophoresis.

    PubMed

    Yoshimura, Yuki; Tomita, Masahiro; Mizutani, Fumio; Yasukawa, Tomoyuki

    2014-07-15

    We report a simple device with an array of 10,000 (100 × 100) microwells for producing vertical pairs of cells in individual microwells with a rapid manipulation based on positive dielectrophoresis (p-DEP). The areas encircled with micropoles which fabricated from an electrical insulating photosensitive polymer were used as microwells. The width (14 μm) and depth (25 μm) of the individual microwells restricted the size to two vertically aligned cells. The DEP device for the manipulation of cells consisted of a microfluidic channel with an upper indium tin oxide (ITO) electrode and a lower microwell array electrode fabricated on an ITO substrate. Mouse myeloma cells stained in green were trapped within 1 s in the microwells by p-DEP by applying an alternating current voltage between the upper ITO and the lower microwell array electrode. The cells were retained inside the wells even after switching off the voltage and washing with a fluidic flow. Other myeloma cells stained in blue were then trapped in the microwells occupied by the cells stained in green to form the vertical cell pairing in the microwells. Cells stained in different colors were paired within only 1 min and a pairing efficiency of over 50% was achieved.

  18. Solar cell array design handbook, volume 1

    NASA Technical Reports Server (NTRS)

    Rauschenbach, H. S.

    1976-01-01

    Twelve chapters discuss the following: historical developments, the environment and its effects, solar cells, solar cell filters and covers, solar cell and other electrical interconnections, blocking and shunt diodes, substrates and deployment mechanisms, material properties, design synthesis and optimization, design analysis, procurement, production and cost aspects, evaluation and test, orbital performance, and illustrative design examples. A comprehensive index permits rapid locating of desired topics. The handbook consists of two volumes: Volume 1 is of an expository nature while Volume 2 contains detailed design data in an appendix-like fashion. Volume 2 includes solar cell performance data, applicable unit conversion factors and physical constants, and mechanical, electrical, thermal optical, magnetic, and outgassing material properties. Extensive references are provided.

  19. Fabrication of cell container arrays with overlaid surface topographies.

    PubMed

    Truckenmüller, Roman; Giselbrecht, Stefan; Escalante-Marun, Maryana; Groenendijk, Max; Papenburg, Bernke; Rivron, Nicolas; Unadkat, Hemant; Saile, Volker; Subramaniam, Vinod; van den Berg, Albert; van Blitterswijk, Clemens; Wessling, Matthias; de Boer, Jan; Stamatialis, Dimitrios

    2012-02-01

    This paper presents cell culture substrates in the form of microcontainer arrays with overlaid surface topographies, and a technology for their fabrication. The new fabrication technology is based on microscale thermoforming of thin polymer films whose surfaces are topographically prepatterned on a micro- or nanoscale. For microthermoforming, we apply a new process on the basis of temporary back moulding of polymer films and use the novel concept of a perforated-sheet-like mould. Thermal micro- or nanoimprinting is applied for prepatterning. The novel cell container arrays are fabricated from polylactic acid (PLA) films. The thin-walled microcontainer structures have the shape of a spherical calotte merging into a hexagonal shape at their upper circumferential edges. In the arrays, the cell containers are arranged densely packed in honeycomb fashion. The inner surfaces of the highly curved container walls are provided with various topographical micro- and nanopatterns. For a first validation of the microcontainer arrays as in vitro cell culture substrates, C2C12 mouse premyoblasts are cultured in containers with microgrooved surfaces and shown to align along the grooves in the three-dimensional film substrates. In future stem-cell-biological and tissue engineering applications, microcontainers fabricated using the proposed technology may act as geometrically defined artificial microenvironments or niches.

  20. Cicada-inspired cell-instructive nanopatterned arrays

    PubMed Central

    Diu, Ting; Faruqui, Nilofar; Sjöström, Terje; Lamarre, Baptiste; Jenkinson, Howard F.; Su, Bo; Ryadnov, Maxim G.

    2014-01-01

    Biocompatible surfaces hold key to a variety of biomedical problems that are directly related to the competition between host-tissue cell integration and bacterial colonisation. A saving solution to this is seen in the ability of cells to uniquely respond to physical cues on such surfaces thus prompting the search for cell-instructive nanoscale patterns. Here we introduce a generic rationale engineered into biocompatible, titanium, substrates to differentiate cell responses. The rationale is inspired by cicada wing surfaces that display bactericidal nanopillar patterns. The surfaces engineered in this study are titania (TiO2) nanowire arrays that are selectively bactericidal against motile bacteria, while capable of guiding mammalian cell proliferation according to the type of the array. The concept holds promise for clinically relevant materials capable of differential physico-mechanical responses to cellular adhesion. PMID:25409910

  1. Cicada-inspired cell-instructive nanopatterned arrays.

    PubMed

    Diu, Ting; Faruqui, Nilofar; Sjöström, Terje; Lamarre, Baptiste; Jenkinson, Howard F; Su, Bo; Ryadnov, Maxim G

    2014-11-20

    Biocompatible surfaces hold key to a variety of biomedical problems that are directly related to the competition between host-tissue cell integration and bacterial colonisation. A saving solution to this is seen in the ability of cells to uniquely respond to physical cues on such surfaces thus prompting the search for cell-instructive nanoscale patterns. Here we introduce a generic rationale engineered into biocompatible, titanium, substrates to differentiate cell responses. The rationale is inspired by cicada wing surfaces that display bactericidal nanopillar patterns. The surfaces engineered in this study are titania (TiO2) nanowire arrays that are selectively bactericidal against motile bacteria, while capable of guiding mammalian cell proliferation according to the type of the array. The concept holds promise for clinically relevant materials capable of differential physico-mechanical responses to cellular adhesion.

  2. Cicada-inspired cell-instructive nanopatterned arrays

    NASA Astrophysics Data System (ADS)

    Diu, Ting; Faruqui, Nilofar; Sjöström, Terje; Lamarre, Baptiste; Jenkinson, Howard F.; Su, Bo; Ryadnov, Maxim G.

    2014-11-01

    Biocompatible surfaces hold key to a variety of biomedical problems that are directly related to the competition between host-tissue cell integration and bacterial colonisation. A saving solution to this is seen in the ability of cells to uniquely respond to physical cues on such surfaces thus prompting the search for cell-instructive nanoscale patterns. Here we introduce a generic rationale engineered into biocompatible, titanium, substrates to differentiate cell responses. The rationale is inspired by cicada wing surfaces that display bactericidal nanopillar patterns. The surfaces engineered in this study are titania (TiO2) nanowire arrays that are selectively bactericidal against motile bacteria, while capable of guiding mammalian cell proliferation according to the type of the array. The concept holds promise for clinically relevant materials capable of differential physico-mechanical responses to cellular adhesion.

  3. Comparative Study on Synthesizing Reconfigurable Time- Modulated Linear Arrays using Differential Evolution, Artificial Bee Colony and Particle Swarm Optimization

    NASA Astrophysics Data System (ADS)

    Mandal, S. K.; Singh, Harshavardhan; Mahanti, G. K.; Ghatak, Rowdra

    2014-10-01

    This paper presents a new technique based on optimization tools to design phase only, digitally controlled, reconfigurable antenna arrays through time modulation. In the proposed approach, the on-time durations of the time-modulated elements and the static amplitudes of the array elements are perturbed in such a way that the same on-time sequence and discrete values of static amplitudes for four bit digital attenuators produces either a pencil or a flat-top beam pattern, depending on the suitable discrete phase distributions of five bit digital phase shifters. In order to illustrate the technique, three optimization tools: differential evolution (DE), artificial bee colony (ABC), and particle swarm optimization (PSO) are employed and their performances are compared. The numerical results for a 20-element linear array are presented.

  4. Memory cell operation based on small Josephson junctions arrays

    NASA Astrophysics Data System (ADS)

    Braiman, Y.; Nair, N.; Rezac, J.; Imam, N.

    2016-12-01

    In this paper we analyze a cryogenic memory cell circuit based on a small coupled array of Josephson junctions. All the basic memory operations (e.g., write, read, and reset) are implemented on the same circuit and different junctions in the array can in principle be utilized for these operations. The presented memory operation paradigm is fundamentally different from conventional single quantum flux operation logics (SFQ). As an example, we demonstrate memory operation driven by a SFQ pulse employing an inductively coupled array of three Josephson junctions. We have chosen realistic Josephson junction parameters based on state-of-the-art fabrication capabilities and have calculated access times and access energies for basic memory cell operations. We also implemented an optimization procedure based on the simulated annealing algorithm to calculate the optimized and typical values of access times and access energies.

  5. Studies of encapsulant materials for terrestrial solar-cell arrays

    NASA Technical Reports Server (NTRS)

    Carmichael, D. C. (Compiler)

    1975-01-01

    Study 1 of this contract is entitled ""Evaluation of World Experience and Properties of Materials for Encapsulation of Terrestrial Solar-Cell Arrays.'' The approach of this study is to review and analyze world experience and to compile data on properties of encapsulants for photovoltaic cells and for related applications. The objective of the effort is to recommend candidate materials and processes for encapsulating terrestrial photovoltaic arrays at low cost for a service life greater than 20 years. The objectives of Study 2, ""Definition of Encapsulant Service Environments and Test Conditions,'' are to develop the climatic/environmental data required to define the frequency and duration of detrimental environmental conditions in a 20-year array lifetime and to develop a corresponding test schedule for encapsulant systems.

  6. Method of low temperature operation of an electrochemical cell array

    DOEpatents

    Singh, Prabhakar; Ruka, Roswell J.; Bratton, Raymond J.

    1994-01-01

    In the method of operating an electrochemical cell generator apparatus containing a generator chamber (20) containing an array of cells (12) having interior and exterior electrodes with solid electrolyte between the electrodes, where a hot gas (F) contacts the outside of the cells (12) and the generating chamber normally operates at over 850.degree. C., where N.sub.2 gas is fed to contact the interior electrode of the cells (12) in any case when the generating chamber (20) temperature drops for whatever reason to within the range of from 550.degree. C. to 800.degree. C., to eliminate cracking within the cells (12).

  7. Method of low temperature operation of an electrochemical cell array

    DOEpatents

    Singh, P.; Ruka, R.J.; Bratton, R.J.

    1994-04-26

    A method is described for operating an electrochemical cell generator apparatus containing a generator chamber containing an array of cells having interior and exterior electrodes with solid electrolyte between the electrodes, where a hot gas contacts the outside of the cells and the generating chamber normally operates at over 850 C, where N[sub 2] gas is fed to contact the interior electrode of the cells in any case when the generating chamber temperature drops for whatever reason to within the range of from 550 C to 800 C, to eliminate cracking within the cells. 2 figures.

  8. Thermal-Independent Properties of PIN-PMN-PT Single-Crystal Linear-Array Ultrasonic Transducers

    PubMed Central

    Chen, Ruimin; Wu, Jinchuan; Lam, Kwok Ho; Yao, Liheng; Zhou, Qifa; Tian, Jian; Han, Pengdi; Shung, K. Kirk

    2013-01-01

    In this paper, low-frequency 32-element linear-array ultrasonic transducers were designed and fabricated using both ternary Pb(In1/2Nb1/2)–Pb(Mg1/3Nb2/3)–PbTiO3 (PIN-PMN-PT) and binary Pb(Mg1/3Nb2/3)–PbTiO3 (PMN-PT) single crystals. Performance of the array transducers was characterized as a function of temperature ranging from room temperature to 160°C. It was found that the array transducers fabricated using the PIN-PMN-PT single crystal were capable of satisfactory performance at 160°C, having a −6-dB bandwidth of 66% and an insertion loss of 37 dB. The results suggest that the potential of PIN-PMN-PT linear-array ultrasonic transducers for high-temperature ultrasonic transducer applications is promising. PMID:23221227

  9. 2D Numerical Modeling for Transducers with Combined Pseudospectral and Finite Difference Methods: Application to High Frequency Linear Arrays

    NASA Astrophysics Data System (ADS)

    Guiroy, Axel; Certon, Dominique; Boy, Philippe; Lethiecq, Marc; Levassort, Franck

    A 2D numerical model based on a hybrid finite-difference (FD) and pseudospectral (PS) method adapted to high frequency linear arrays is presented. This model, coupled with the DREAM toolbox, was used to simulate the 1-way radiation pattern in water of a 50 MHz linear array with 64 elements (at a focal distance of 10 mm). The influence of several parameters of the internal structure of the array on the radiation pattern was studied. The variation of element widths, kerf widths and kerf depths was evaluated on the main properties of the pressure field (i.e. spatial resolutions, sensitivity and depth of field) in the focal zone. These simulations were performed using experimental data previously measured for materials used and in particular for the PZT piezoelectric thick film. Results show that a trade-off can be found between the technological aspects (width of elements and kerf) and performance of the array. Finally, a kerfless configuration was evaluated and it is shown that this is also a viable option.

  10. An advanced space photovoltaic concentrator array using Fresnel lenses, gallium arsenide cells, and prismatic cell covers

    NASA Technical Reports Server (NTRS)

    O'Neill, Mark J.; Piszczor, Michael F.

    1988-01-01

    The current status of a space concentrator array which uses refractive optics, gallium arsenide cells, and prismatic cell covers to achieve excellent performance at a very low array mass is documented. The prismatically covered cells have established records for space cell performance (24.2 percent efficient at 100 AM0 suns and 25 C) and terrestrial single-junction cell performance (29.3 percent efficient at 200 AM1.5 suns and 25 C).

  11. An advanced space photovoltaic concentrator array using Fresnel lenses, gallium arsenide cells, and prismatic cell covers

    NASA Technical Reports Server (NTRS)

    O'Neill, Mark J.; Piszczor, Michael F.

    1988-01-01

    The current status of a space concentrator array which uses refractive optics, gallium arsenide cells, and prismatic cell covers to achieve excellent performance at a very low array mass is documented. The prismatically covered cells have established records for space cell performance (24.2 percent efficient at 100 AM0 suns and 25 C) and terrestrial single-junction cell performance (29.3 percent efficient at 200 AM1.5 suns and 25 C).

  12. Adaptive synchronization in an array of linearly coupled neural networks with reaction-diffusion terms and time delays

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Teng, Zhidong; Jiang, Haijun

    2012-10-01

    In this paper, the adaptive synchronization in an array of linearly coupled neural networks with reaction-diffusion terms and time delays is discussed. Based on the LaSalle invariant principle of functional differential equations and the adaptive feedback control technique, some sufficient conditions for adaptive synchronization of such a system are obtained. Finally, a numerical example is given to show the effectiveness of the proposed synchronization method.

  13. Design and prototype of radar sensor with Vivaldi linear array for through-wall radar imaging: an experimental study

    NASA Astrophysics Data System (ADS)

    Yılmaz, Betül; Özdemir, Caner

    2016-10-01

    We present a radar sensor that was designed to detect and image moving objects/targets on the other side of a wall. The radar sensor was composed of a linear array of Vivaldi antenna elements, an radio frequency (RF) switch, a microcontroller unit, and an RF transceiver. For the linear array, a total of eight antenna elements were used as sensors in synthetic aperture radar (SAR) configuration in the cross-range axis to improve the resolution in this dimension. Design steps of Vivaldi antenna elements and the entire linear array were presented. After the design, the prototyping procedure and the details of the radar sensor were given. Through-the-wall radar (TWR) imaging experiments were performed for stationary and moving targets using the assembled sensor. The resultant TWR images after these experiments were presented. During the image formation, a back-projection type image focusing algorithm was implemented and applied to increase the signal-to-noise ratio of the raw images. The constructed radar images demonstrated that our radar sensor could successfully detect and image both stationary and moving targets on the other side of the wall.

  14. High-speed height measurement by a light-source-stepping method using a linear LED array.

    PubMed

    Fujigaki, Motoharu; Oura, Yohei; Asai, Daisuke; Murata, Yorinobu

    2013-10-07

    High-speed height measurement is required in industrial fields for analyzing the behavior of a breaking object, a vibrating object or a rotating object. A shape measurement performed using a phase-shifting method can measure the shape with high spatial resolution because the coordinates can be obtained pixel by pixel. A light-source-stepping method (LSSM) that uses a linear LED array by means of a whole-space tabulation method (WSTM) has been proposed. Accurate shape measurement can be performed using this method. The response speed of the LED array is greater than 12 kHz. In this paper, height measurement is performed using WSTM and LSSM with a linear LED array and a high-speed camera. It was verified that the response speed of the linear LED is greater than 200 kHz. The phase shifting was performed at 12 kHz, and the height measurement of the vibrating woofer was performed at 4 kHz using a 3-step phase-shifting method.

  15. A spatial capture-recapture model to estimate fish survival and location from linear continuous monitoring arrays

    USGS Publications Warehouse

    Raabe, Joshua K.; Gardner, Beth; Hightower, Joseph E.

    2013-01-01

    We developed a spatial capture–recapture model to evaluate survival and activity centres (i.e., mean locations) of tagged individuals detected along a linear array. Our spatially explicit version of the Cormack–Jolly–Seber model, analyzed using a Bayesian framework, correlates movement between periods and can incorporate environmental or other covariates. We demonstrate the model using 2010 data for anadromous American shad (Alosa sapidissima) tagged with passive integrated transponders (PIT) at a weir near the mouth of a North Carolina river and passively monitored with an upstream array of PIT antennas. The river channel constrained migrations, resulting in linear, one-dimensional encounter histories that included both weir captures and antenna detections. Individual activity centres in a given time period were a function of the individual’s previous estimated location and the river conditions (i.e., gage height). Model results indicate high within-river spawning mortality (mean weekly survival = 0.80) and more extensive movements during elevated river conditions. This model is applicable for any linear array (e.g., rivers, shorelines, and corridors), opening new opportunities to study demographic parameters, movement or migration, and habitat use.

  16. Linear array of conserved sequence motifs to discriminate protein subfamilies: study on pyridine nucleotide-disulfide reductases

    PubMed Central

    Avila, César L; Rapisarda, Viviana A; Farías, Ricardo N; De Las Rivas, Javier; Chehín, Rosana

    2007-01-01

    Background The pyridine nucleotide disulfide reductase (PNDR) is a large and heterogeneous protein family divided into two classes (I and II), which reflect the divergent evolution of its characteristic disulfide redox active site. However, not all the PNDR members fit into these categories and this suggests the need of further studies to achieve a more comprehensive classification of this complex family. Results A workflow to improve the clusterization of protein families based on the array of linear conserved motifs is designed. The method is applied to the PNDR large family finding two main groups, which correspond to PNDR classes I and II. However, two other separate protein clusters, previously classified as class I in most databases, are outgrouped: the peroxide reductases (NAOX, NAPE) and the type II NADH dehydrogenases (NDH-2). In this way, two novel PNDR classes III and IV for NAOX/NAPE and NDH-2 respectively are proposed. By knowledge-driven biochemical and functional data analyses done on the new class IV, a linear array of motifs putatively related to Cu(II)-reductase activity is detected in a specific subset of NDH-2. Conclusion The results presented are a novel contribution to the classification of the complex and large PNDR protein family, supporting its reclusterization into four classes. The linear array of motifs detected within the class IV PNDR subfamily could be useful as a signature for a particular subgroup of NDH-2. PMID:17367536

  17. Microphthalmia with linear skin defects (MLS) syndrome evaluated by prenatal karyotyping, FISH and array comparative genomic hybridization.

    PubMed

    Cain, Colyn Cargile; Saul, Daniel; Attanasio, Lisa; Oehler, Erin; Hamosh, Ada; Blakemore, Karin; Stetten, Gail

    2007-04-01

    To explore the utility of comparative genomic hybridization to BAC arrays (array CGH) for prenatal diagnosis of microphthalmia and linear skin defects syndrome. We used karyotype analysis, FISH and array CGH to investigate an X;Y translocation. Replication studies were done on cultured amniocytes and lymphoblasts. We describe a severe case of MLS syndrome that presented prenatally with multiple anomalies including cystic hygroma, microphthalmia, intrauterine growth restriction and a complex congenital heart defect. Cytogenetic analysis of amniocytes revealed an unbalanced de novo translocation between chromosomes X and Y [karyotype 46,X,der(X)t(X;Y)(p22.3;q11.2).ish der(X)(DXZ1+,DMD+,KAL-,STS-,SRY-),22q11.2 (Tuple1 x 2)]. MLS diagnosis was made at birth and the prenatal karyotype was confirmed. Replication studies showed the derivative X chromosome was the inactive X. Array CGH confirmed the X and Y imbalances seen in the karyotype and also showed twelve BACs in the MLS region were deleted as a result of the translocation. FISH with BAC clones verified the array findings and placed the X breakpoint in Xp22.2, resulting in the amended karyotype, 46,X,der(X)t(X;Y)(p22.2;q11.2).ish der(X)(DXZ1+,DMD+,KAL-,STS-,SRY-),22q11.2(Tuple1 x 2) arr cgh Xp22.33p22.2(LLNOYCO3M15D10 -->GS1-590J6)x 1,Yq11.222q23(RP11-20H21-->RP11-79J10)x 1. The sensitivity of array CGH was valuable in detecting monosomy of the MLS critical region. Array CGH should be considered for the prenatal diagnosis of this syndrome. Copyright (c) 2007 John Wiley & Sons, Ltd.

  18. Characterization and simulation of linear scintillator arrays for low-energy x-ray detection

    NASA Astrophysics Data System (ADS)

    Franco, L.; Gómez, F.; Badano, A.

    2008-11-01

    Current x-ray imaging in many industrial and medical applications uses different scintillator materials coupled to photodiode arrays. Knowledge of the light distribution and photoelectron signal allows for the improvement of the imaging properties of such devices. We have measured and simulated the pixel scintillation light distribution collected by the photodiode arrays for four commercial scintillator arrays made of cesium iodide, cadmium tungstate and gadolinium oxysulfide with pitches of 0.8 mm and 1.6 mm. We used a collimated low-energy x-ray beam to study the collected signal in each array element and the effective fill factors determined from the photodiode geometry, backing material and radiation transport in the scintillator. A proper description of the optical parameters of these detectors provides excellent agreement of the experimental results with Monte Carlo simulations performed with MANTIS.

  19. Astronomical camera using a high-performance indium antimonide linear array

    NASA Technical Reports Server (NTRS)

    Herring, M.; Bailey, G. C.; Kupferman, P. N.; Macenka, S.

    1984-01-01

    The development and current status of InSb line arrays for astronomy are reviewed. Instrument concepts are currently being developed for an infrared instrument for NASA's Space Telescope which would use such detectors for both spectroscopy and imaging. Preliminary performance measurements are given for a simple pushbroom camera, using a 128-element line array, designed for operation on the 24-inch Cassegrain telescope at the JPL Table Mountain Observatory. The design and construction of the camera are described.

  20. Nanoliter scale microbioreactor array for quantitative cell biology.

    PubMed

    Lee, Philip J; Hung, Paul J; Rao, Vivek M; Lee, Luke P

    2006-05-05

    A nanoliter scale microbioreactor array was designed for multiplexed quantitative cell biology. An addressable 8 x 8 array of three nanoliter chambers was demonstrated for observing the serum response of HeLa human cancer cells in 64 parallel cultures. The individual culture unit was designed with a "C" shaped ring that effectively decoupled the central cell growth regions from the outer fluid transport channels. The chamber layout mimics physiological tissue conditions by implementing an outer channel for convective "blood" flow that feeds cells through diffusion into the low shear "interstitial" space. The 2 microm opening at the base of the "C" ring established a differential fluidic resistance up to 3 orders of magnitude greater than the fluid transport channel within a single mold microfluidic device. Three-dimensional (3D) finite element simulation were used to predict fluid transport properties based on chamber dimensions and verified experimentally. The microbioreactor array provided a continuous flow culture environment with a Peclet number (0.02) and shear stress (0.01 Pa) that approximated in vivo tissue conditions without limiting mass transport (10 s nutrient turnover). This microfluidic design overcomes the major problems encountered in multiplexing nanoliter culture environments by enabling uniform cell loading, eliminating shear, and pressure stresses on cultured cells, providing stable control of fluidic addressing, and permitting continuous on-chip optical monitoring.

  1. The photoemissive cell of a vacuum ultraviolet radiation detector array

    NASA Astrophysics Data System (ADS)

    Il'ichev, E. A.; Kuleshov, A. E.; Nabiev, R. M.; Petrukhin, G. N.; Rychkov, G. S.; Teverovskaya, E. G.

    2017-04-01

    A photoemissive "solar-blind" cell of a vacuum ultraviolet detector array for the 50-225 nm wavelength range is described. The cell is a cavity in the shape of frustum of a pyramid in a silicon wafer, the walls of which are coated by polycrystalline diamond film acting the part of a photosensitive cathode. The design of the cell allows one to manage the work of the detector in the "pass through" mode; i.e., photons fall to one side of the wafer, and photoelectrons release from its opposite side. Estimation of photosensitivity of the cell gives a value of about ten photons.

  2. Fabrication of long linear arrays of plastic optical fibers with squared ends for the use of code mark printing lithography

    NASA Astrophysics Data System (ADS)

    Horiuchi, Toshiyuki; Watanabe, Jun; Suzuki, Yuta; Iwasaki, Jun-ya

    2017-05-01

    Two dimensional code marks are often used for the production management. In particular, in the production lines of liquid-crystal-display panels and others, data on fabrication processes such as production number and process conditions are written on each substrate or device in detail, and they are used for quality managements. For this reason, lithography system specialized in code mark printing is developed. However, conventional systems using lamp projection exposure or laser scan exposure are very expensive. Therefore, development of a low-cost exposure system using light emitting diodes (LEDs) and optical fibers with squared ends arrayed in a matrix is strongly expected. In the past research, feasibility of such a new exposure system was demonstrated using a handmade system equipped with 100 LEDs with a central wavelength of 405 nm, a 10×10 matrix of optical fibers with 1 mm square ends, and a 10X projection lens. Based on these progresses, a new method for fabricating large-scale arrays of finer fibers with squared ends was developed in this paper. At most 40 plastic optical fibers were arranged in a linear gap of an arraying instrument, and simultaneously squared by heating them on a hotplate at 120°C for 7 min. Fiber sizes were homogeneous within 496+/-4 μm. In addition, average light leak was improved from 34.4 to 21.3% by adopting the new method in place of conventional one by one squaring method. Square matrix arrays necessary for printing code marks will be obtained by piling the newly fabricated linear arrays up.

  3. Structure of cortical microtubule arrays in plant cells

    PubMed Central

    1978-01-01

    Serial sectioning was used to track the position and measure the lengths of cortical microtubules in glutaraldehyde-osmium tetroxide- fixed root tip cells. Microtubules lying against the longitudinal walls during interphase, those overlying developing xylem thickenings, and those in pre-prophase bands are oriented circumferentially but on average are only about one-eighth of the cell circumference in length, i.e., 2-4 micrometer. The arrays consist of overlapping component microtubules, interconnected by cross bridges where they are grouped and also connected to the plasma membrane. Microtubule lengths vary greatly in any given array, but the probability that any pass right around the cell is extremely low. The majority of the microtubule terminations lie in statistically random positions in the arrays, but nonrandomness in the form of groups of terminations and terminations in short lines parallel to the axis of cell elongation has been observed. Low temperature induces microtubule shortening and increases the frequency of C-shaped terminations over the 1.7% found under normal conditions; colchicine and high pressures produce abnormally large proportions of very short microtubules amongst those that survive the treatments. Deuterium oxide (D2O) treatment probably induces the formation of additional microtubules as distinct from increasing the length of those already present. The distribution of C-shaped terminations provides evidence for at least local polarity in the arrays. The validity of the findings is discussed, along with implications for the development, maintenance, and orientation of the arrays and their possible relationship to the orientation of cellulose deposition. PMID:350889

  4. Shrink-induced single-cell plastic microwell array.

    PubMed

    Lew, Valerie; Nguyen, Diep; Khine, Michelle

    2011-12-01

    The ability to interrogate and track single cells over time in a high-throughput format would provide critical information for fundamental biological understanding of processes and for various applications, including drug screening and toxicology. We have developed an ultrarapid and simple method to create single-cell wells of controllable diameter and depth with commodity shrink-wrap film and tape. Using a programmable CO(2) laser, we cut hole arrays into the tape. The tape then serves as a shadow mask to selectively etch wells into commodity shrink-wrap film by O(2) plasma. When the shrink-wrap film retracts upon briefly heating, high-aspect plastic microwell arrays with diameters down to 20 μm are readily achieved. We calibrated the loading procedure with fluorescent microbeads. Finally, we demonstrate the utility of the wells by loading fluorescently labeled single human embryonic stem cells into the wells.

  5. Thermoelastic analysis of solar cell arrays and their material properties

    NASA Technical Reports Server (NTRS)

    Salama, M. A.; Rowe, W. M.; Yasui, R. K.

    1973-01-01

    A thermoelastic stress analysis procedure is reported for predicting the thermally induced stresses and failures in silicon solar cell arrays. A prerequisite for the analysis is the characterization of the temperature-dependent thermal and mechanical properties of the solar cell materials. Extensive material property testing was carried out in the temperature range -200 to +200 C for the filter glass, P- and N-type silicon, interconnector metals, solder, and several candidate silicone rubber adhesives. The analysis procedure is applied to several solar cell array design configurations. Results of the analysis indicate the optimum design configuration, with respect to compatible materials, effect of the solder coating, and effect of the interconnector geometry. Good agreement was found between results of the analysis and the test program.

  6. Design of High Temperature Ultrasonic Linear Arrays for Under-Sodium Viewing

    SciTech Connect

    Griffin, Jeffrey W.; Bond, Leonard J.; Jones, Anthony M.; Peters, Timothy J.

    2010-11-07

    This paper summarizes the design process for high temperature ultrasonic phased array transducers for imaging in liquid sodium at temperatures up to 260C. The project is funded by the USDOE Generation IV Reactor Program and includes collaboration with the Japanese Atomic Energy Agency. The transducer system is being designed to be able to provide images inside a sodium cooled fast reactor, to support operation and maintenance activities including potentially location of looseor damaged parts during service outages. The prototype transducer array is being designed for 8 to 16, 3MHz rectangular lead niobate (K-81) or bismuth titanate (K-15) piezoelectric elements spaced at λ/2 (wavelength in sodium). A nickel or nickel alloy faceplate serves as the sodium wetting surface. Scan angle of the focused ultrasonic beam is ±30 degrees. Imaging spatial resolution is ≤ 1mm. The array is designed to be operated using a commercial phased array control system and it is planned that array testing will be performed in room temperature water, hot oil (260C), and molten sodium (260C).

  7. Size specific transfection to mammalian cells by micropillar array electroporation

    NASA Astrophysics Data System (ADS)

    Zu, Yingbo

    Electroporation serves as a promising non-viral gene delivery approach, while its current configurations carry drawbacks associated with high-voltage electrical pulses and heterogeneous treatment on individual cells. Here, we developed a new micropillar array electroporation (MAE) platform to advance the delivery of plasmid DNA and RNA to mammalian cells. By introducing well-patterned micropillar array on the electrode surface, the number of pillars each cell faces varies with its cell membrane surface area, despite their large population and random locations. In this way, cell size specific electroporation is conveniently done and contributed to a 2.5 3 fold increase on plasmid DNA transfection and an additional 10-55% knockdown with targeting siRNA, respectively. The delivery efficiency varies with the number and size of the micropillars as well as their pattern density. As MAE works like many single cell electroporation is carried out in a parallel fashion, the electrophysiology response of individual cells is representative, which has the potential to gear up the tedious, cell-specific protocol screening process in the current in vitro bulk electroporation (i.e., electroporation to a large population of cells). Its success might facilitate the wide adoption of electroporation as a safe and effective non-viral gene delivery approach needed in many biological research and clinical treatments.

  8. Internal structure of the San Jacinto fault zone at Jackass Flat from data recorded by a dense linear array

    NASA Astrophysics Data System (ADS)

    Qiu, H.; Ben-Zion, Y.; Ross, Z. E.; Share, P.-E.; Vernon, F. L.

    2017-03-01

    The internal structure of the Clark fault in the trifurcation area of the San Jacinto fault zone is imaged using seismograms recorded by a dense linear array (JF) crossing the surface trace of the fault and an adjacent array (TR) to the SW. Delay times between phase arrivals associated with ∼3500 local earthquakes and 9 teleseismic events are used to estimate velocity variations within the arrays. The teleseismic P waves travel faster beneath the TR than the JF array, in contrast to larger-scale tomographic results. Statistical analysis of local P wave delay times indicates that the entire JF array, with an aperture of ∼400 m, is inside a low velocity damage zone. This low velocity zone is bounded on the NE side by a shallow bimaterial interface generating fault zone head waves, and it contains an inner zone of more intense damage generating fault zone trapped waves. The P wave velocity contrast across the local bounding bimaterial interface is 10-15%. The trapping structure is associated with a width of ∼200 m, S wave velocity reduction of ∼35% with respect to the surrounding rock, Q value of ∼20 and depth of ∼3.5 km. The imaging results suggest that the main seismogenic fault is near the SW end of the JF array, in agreement with a prominent geomorphologic feature. The existence of intense local damage on the crustal block with faster larger-scale velocity at depth is consistent with common propagation of earthquake ruptures in the area to the NW.

  9. Internal structure of the San Jacinto fault zone at Jackass Flat from data recorded by a dense linear array

    NASA Astrophysics Data System (ADS)

    Qiu, H.; Ben-Zion, Y.; Ross, Z. E.; Share, P.-E.; Vernon, F. L.

    2017-06-01

    The internal structure of the Clark fault in the trifurcation area of the San Jacinto fault zone is imaged using seismograms recorded by a dense linear array (Jackass Flat, JF) crossing the surface trace of the fault and an adjacent array (TR) to the SW. Delay times between phase arrivals associated with ∼3500 local earthquakes and nine teleseismic events are used to estimate velocity variations within the arrays. The teleseismic P waves travel faster beneath the TR than the JF array, in contrast to larger scale tomographic results. Statistical analysis of local P-wave delay times indicates that the entire JF array, with an aperture of ∼400 m, is inside a low-velocity damage zone. This low-velocity zone is bounded on the NE side by a shallow bimaterial interface generating fault zone head waves, and it contains an inner zone of more intense damage generating fault zone trapped waves. The P-wave velocity contrast across the local bounding bimaterial interface is 10-15 per cent. The trapping structure is associated with a width of ∼200 m, S-wave velocity reduction of ∼35 per cent with respect to the surrounding rock, Q-value of ∼20 and depth of ∼3.5 km. The imaging results suggest that the main seismogenic fault is near the SW end of the JF array, in agreement with a prominent geomorphologic feature. The existence of intense local damage on the crustal block with faster larger scale velocity at depth is consistent with common propagation of earthquake ruptures in the area to the NW.

  10. SKYLAB 1 SOLAR CELL ARRAY INSTALLATION IN VAB

    NASA Technical Reports Server (NTRS)

    1972-01-01

    One of Skylab 1's solar cell arrays installed on the orbital space station in High Bay 2 of the Vehicle Assembly Building today. Skylab 2 in High Bay 1 in visible in the background. Each of the two solar cell arrays on the space station that will be deployed in orbit, is designed to provide 10,500 watts of power at 55 degrees centigrade while in the sunlight portion of each orbit. All power needed to operate the station and the Apollo Telescope mount will be taken from the arrays. The remainder of the power generated will be diverted to battery chargers which will keep the batteries at full charge and ready for use while the orbiting spacecraft cluster is in the Earth's shadow. Each array will have almost 1,177 square feet of surface area to turn sunlight into electrical power. Skylab 1 is schedule for launch April 30, 1973 and Skylab 2, carrying the astronauts Conrad, Kerwin and Weitz to dock with the space station and enter it to live and work for 28 days, will be launched a day later.

  11. Single-cell chromosomal imbalances detection by array CGH

    PubMed Central

    Le Caignec, Cedric; Spits, Claudia; Sermon, Karen; De Rycke, Martine; Thienpont, Bernard; Debrock, Sophie; Staessen, Catherine; Moreau, Yves; Fryns, Jean-Pierre; Van Steirteghem, Andre; Liebaers, Inge; Vermeesch, Joris R.

    2006-01-01

    Genomic imbalances are a major cause of constitutional and acquired disorders. Therefore, aneuploidy screening has become the cornerstone of preimplantation, prenatal and postnatal genetic diagnosis, as well as a routine aspect of the diagnostic workup of many acquired disorders. Recently, array comparative genomic hybridization (array CGH) has been introduced as a rapid and high-resolution method for the detection of both benign and disease-causing genomic copy-number variations. Until now, array CGH has been performed using a significant quantity of DNA derived from a pool of cells. Here, we present an array CGH method that accurately detects chromosomal imbalances from a single lymphoblast, fibroblast and blastomere within a single day. Trisomy 13, 18, 21 and monosomy X, as well as normal ploidy levels of all other chromosomes, were accurately determined from single fibroblasts. Moreover, we showed that a segmental deletion as small as 34 Mb could be detected. Finally, we demonstrated the possibility to detect aneuploidies in single blastomeres derived from preimplantation embryos. This technique offers new possibilities for genetic analysis of single cells in general and opens the route towards aneuploidy screening and detection of unbalanced translocations in preimplantation embryos in particular. PMID:16698960

  12. Size Specific Transfection to Mammalian Cells by Micropillar Array Electroporation

    NASA Astrophysics Data System (ADS)

    Zu, Yingbo; Huang, Shuyan; Lu, Yang; Liu, Xuan; Wang, Shengnian

    2016-12-01

    Electroporation serves as a promising non-viral gene delivery approach, while its current configuration carries several drawbacks associated with high-voltage electrical pulses and heterogeneous treatment on individual cells. Here we developed a new micropillar array electroporation (MAE) platform to advance the electroporation-based delivery of DNA and RNA probes into mammalian cells. By introducing well-patterned micropillar array texture on the electrode surface, the number of pillars each cell faces varies with its plasma membrane surface area, despite their large population and random locations. In this way, cell size specific electroporation is conveniently carried out, contributing to a 2.5~3 fold increase on plasmid DNA transfection and an additional 10–55% transgene knockdown with siRNA probes, respectively. The delivery efficiency varies with the number and size of micropillars as well as their pattern density. As MAE works like many single cell electroporation are carried out in parallel, the electrophysiology response of individual cells is representative, which has potentials to facilitate the tedious, cell-specific protocol screening process in current bulk electroporation (i.e., electroporation to a large population of cells). Its success might promote the wide adoption of electroporation as a safe and effective non-viral gene delivery approach needed in many biological research and clinical treatments.

  13. Electrical impedance characterization of cell growth on interdigitated microelectrode array.

    PubMed

    Lee, Gi Hyun; Pyun, Jae-Chul; Cho, Sungbo

    2014-11-01

    Electrical cell-substrate impedance sensing is a method for label-free and real-time monitoring of biological cells, which has been increasingly employed in the diagnostic and pharmaceutical industries. In this study, we fabricated an interdigitated electrode (IDE) array, which consists of 10 fingers, with a length of 1.2 mm, width of 50 μm, spacing of 50 μm, and thickness of 75 nm. The impedance spectra of the fabricated IDE were measured without or with cells in the frequency range of 100 Hz to 100 kHz using a lock-in amplifier based system and characterized by equivalent circuit modelling. Regarding the total impedance as a series resistance (R) and capacitance (C) model, R and C parameters were traced at a selected frequency during cell growth. It was able to monitor cell adherence and proliferation dependent on the behaviours and characteristics of cells on the fabricated IDE array by monitoring RC parameters. The degree of changes in RC value during cell growth was dependent on the type of cells used.

  14. Size Specific Transfection to Mammalian Cells by Micropillar Array Electroporation

    PubMed Central

    Zu, Yingbo; Huang, Shuyan; Lu, Yang; Liu, Xuan; Wang, Shengnian

    2016-01-01

    Electroporation serves as a promising non-viral gene delivery approach, while its current configuration carries several drawbacks associated with high-voltage electrical pulses and heterogeneous treatment on individual cells. Here we developed a new micropillar array electroporation (MAE) platform to advance the electroporation-based delivery of DNA and RNA probes into mammalian cells. By introducing well-patterned micropillar array texture on the electrode surface, the number of pillars each cell faces varies with its plasma membrane surface area, despite their large population and random locations. In this way, cell size specific electroporation is conveniently carried out, contributing to a 2.5~3 fold increase on plasmid DNA transfection and an additional 10–55% transgene knockdown with siRNA probes, respectively. The delivery efficiency varies with the number and size of micropillars as well as their pattern density. As MAE works like many single cell electroporation are carried out in parallel, the electrophysiology response of individual cells is representative, which has potentials to facilitate the tedious, cell-specific protocol screening process in current bulk electroporation (i.e., electroporation to a large population of cells). Its success might promote the wide adoption of electroporation as a safe and effective non-viral gene delivery approach needed in many biological research and clinical treatments. PMID:27924861

  15. Spin-Orbit Coupling in Quantum Dot Cell Arrays

    NASA Astrophysics Data System (ADS)

    Fernando, Rojas; Francisco, Mireles; Ernesto, Cota; Ulloa, Sergio E.

    2002-03-01

    We investigate the role of spin-orbit interaction on the energy spectra, charge and spin configurations of a planar semiconductor quantum dot cell array in a square geometry. The quantum dot array is assumed to be formed by electrical gate confinement, for instance, of a two dimensional electron gas on a semiconductor heterojunction. Hence, it is expected that while tunneling between neighboring dots, the hopping electron will couple its spin with its orbital degree of freedom, due to the interfacial electric fields defining the structure. The spin-orbit (Rashba-like) coupling effect is modelled in a tight-binding formalism with nearest-neighbor spin-dependent interactions. An extended Hubbard Hamiltonian is used to describe the electrons in each cell (with an excess of two electrons per cell), taking into account intra- and inter-cell Coulomb interactions, as well as intra-cell tunneling. We present results for the energy spectrum as a function of the relevant parameters in the cell: tunneling amplitude, spin-orbit coupling t_SO, and dot size imperfections. We find that a number of spin-degeneracies are broken with increasing t_SO. The charge- and spin-polarizations in the cell in the presence of a driver, as well as the interplay between cells will be discussed for different system parameters.

  16. Iron-copper metallization for flexible solar/cell arrays

    NASA Technical Reports Server (NTRS)

    Lavendel, H. W.

    1983-01-01

    The feasibility of a copper-base metallization for shallow-junction cells applied in flexible solar arrays in space is discussed. This type of metallization will reduce usage of precious metals (such as silver), increase case of bonding (by welding or by soldering) and eliminate heavy high Z interconnects (such as molybdenum). The main points of concern are stability against thermally induced diffusion of copper into silicon which causes degradation of shallow cell junctions, and low series resistance of the contact with semiconductor which promotes cell efficiency.

  17. Status of wraparound contact solar cells and arrays

    NASA Technical Reports Server (NTRS)

    Baraona, C. R.; Young, L. E.

    1978-01-01

    Solar cells with wraparound contacts provide the following advantages in array assembly: (1) eliminate the need for discretely formed, damage susceptible series tabs; (2) eliminate the n gap problem by allowing the use of uniform covers over the entire cell surface; (3) allow a higher packing factor by reducing the additional series spacing formly required for forming, and routing the series tab; and (4) allow the cell bonding to the interconnect system to be a single-side function wherein series contacts can be made at the same time parallel contracts are made.

  18. Cross-correlation, triangulation, and curved-wavefront focusing of coral reef sound using a bi-linear hydrophone array.

    PubMed

    Freeman, Simon E; Buckingham, Michael J; Freeman, Lauren A; Lammers, Marc O; D'Spain, Gerald L

    2015-01-01

    A seven element, bi-linear hydrophone array was deployed over a coral reef in the Papahãnaumokuãkea Marine National Monument, Northwest Hawaiian Islands, in order to investigate the spatial, temporal, and spectral properties of biological sound in an environment free of anthropogenic influences. Local biological sound sources, including snapping shrimp and other organisms, produced curved-wavefront acoustic arrivals at the array, allowing source location via focusing to be performed over an area of 1600 m(2). Initially, however, a rough estimate of source location was obtained from triangulation of pair-wise cross-correlations of the sound. Refinements to these initial source locations, and source frequency information, were then obtained using two techniques, conventional and adaptive focusing. It was found that most of the sources were situated on or inside the reef structure itself, rather than over adjacent sandy areas. Snapping-shrimp-like sounds, all with similar spectral characteristics, originated from individual sources predominantly in one area to the east of the array. To the west, the spectral and spatial distributions of the sources were more varied, suggesting the presence of a multitude of heterogeneous biological processes. In addition to the biological sounds, some low-frequency noise due to distant breaking waves was received from end-fire north of the array.

  19. Control and dynamic range extension of linear photodiode arrays by a single board computer

    NASA Astrophysics Data System (ADS)

    McGeorge, Scott W.; Salin, Eric D.

    A complete interface for data acquisition and control of Reticon Series arrays utilizing an inexpensive microcomputer (Rockwell AIM-65) is described and with specific application to atomic spectra (ICP), data collection techniques are illustrated that provide a dynamic range extension for intense signals.

  20. High power density fuel cell comprising an array of microchannels

    DOEpatents

    Sopchak, David A; Morse, Jeffrey D; Upadhye, Ravindra S; Kotovsky, Jack; Graff, Robert T

    2014-05-06

    A phosphoric acid fuel cell according to one embodiment includes an array of microchannels defined by a porous electrolyte support structure extending between bottom and upper support layers, the microchannels including fuel and oxidant microchannels; fuel electrodes formed along some of the microchannels; and air electrodes formed along other of the microchannels. A method of making a phosphoric acid fuel cell according to one embodiment includes etching an array of microchannels in a substrate, thereby forming walls between the microchannels; processing the walls to make the walls porous, thereby forming a porous electrolyte support structure; forming anode electrodes along some of the walls; forming cathode electrodes along other of the walls; and filling the porous electrolyte support structure with a phosphoric acid electrolyte. Additional embodiments are also disclosed.

  1. Micro-magnet arrays for specific single bacterial cell positioning

    NASA Astrophysics Data System (ADS)

    Pivetal, Jérémy; Royet, David; Ciuta, Georgeta; Frenea-Robin, Marie; Haddour, Naoufel; Dempsey, Nora M.; Dumas-Bouchiat, Frédéric; Simonet, Pascal

    2015-04-01

    In various contexts such as pathogen detection or analysis of microbial diversity where cellular heterogeneity must be taken into account, there is a growing need for tools and methods that enable microbiologists to analyze bacterial cells individually. One of the main challenges in the development of new platforms for single cell studies is to perform precise cell positioning, but the ability to specifically target cells is also important in many applications. In this work, we report the development of new strategies to selectively trap single bacterial cells upon large arrays, based on the use of micro-magnets. Escherichia coli bacteria were used to demonstrate magnetically driven bacterial cell organization. In order to provide a flexible approach adaptable to several applications in the field of microbiology, cells were magnetically and specifically labeled using two different strategies, namely immunomagnetic labeling and magnetic in situ hybridization. Results show that centimeter-sized arrays of targeted, isolated bacteria can be successfully created upon the surface of a flat magnetically patterned hard magnetic film. Efforts are now being directed towards the integration of a detection tool to provide a complete micro-system device for a variety of microbiological applications.

  2. Kinetics of Intracellular Ice Formation in One-Dimensional Arrays of Interacting Biological Cells

    PubMed Central

    Irimia, Daniel; Karlsson, Jens O. M.

    2005-01-01

    Although cell-cell interactions are known to significantly affect the kinetics of intracellular ice formation (IIF) during tissue freezing, this effect is not well understood. Progress in elucidating the mechanism and role of intercellular ice propagation in tissue freezing has been hampered in part by limitations in experimental design and data analysis. Thus, using rapid-cooling cryomicroscopy, IIF was measured in adherent cells cultured in micropatterned linear constructs (to control cell-cell interactions and minimize confounding factors). By fitting a Markov chain model to IIF data from micropatterned HepG2 cell pairs, the nondimensional rate of intercellular ice propagation was found to be α = 10.4 ± 0.1. Using this measurement, a new generator matrix was derived to predict the kinetics of IIF in linear four-cell constructs; cryomicroscopic measurements of IIF state probabilities in micropatterned four-cell arrays conformed with theoretical predictions (p < 0.05), validating the modeling assumptions. Thus, the theoretical model was extended to allow prediction of IIF in larger tissues, using Monte Carlo techniques. Simulations were performed to investigate the effects of tissue size and ice propagation rate, for one-dimensional tissue constructs containing up to 100 cells and nondimensional propagation rates in the range 0.1 ≤ α ≤ 1000. PMID:15475590

  3. Micropost arrays for measuring stem cell-derived cardiomyocyte contractility

    PubMed Central

    Beussman, Kevin M.; Rodriguez, Marita L.; Leonard, Andrea; Taparia, Nikita; Thompson, Curtis R.; Sniadecki, Nathan J.

    2015-01-01

    Stem cell-derived cardiomyocytes have the potential to be used to study heart disease and maturation, screen drug treatments, and restore heart function. Here, we discuss the procedures involved in using micropost arrays to measure the contractile forces generated by stem cell-derived cardiomyocytes. Cardiomyocyte contractility is needed for the heart to pump blood, so measuring the contractile forces of cardiomyocytes is a straightforward way to assess their function. Microfabrication and soft lithography techniques are utilized to create identical arrays of flexible, silicone microposts from a common master. Micropost arrays are functionalized with extracellular matrix protein to allow cardiomyocytes to adhere to the tips of the microposts. Live imaging is used to capture videos of the deflection of microposts caused by the contraction of the cardiomyocytes. Image analysis code provides an accurate means to quantify these deflections. The contractile forces produced by a beating cardiomyocyte are calculated by modeling the microposts as cantilever beams. We have used this assay to assess techniques for improving the maturation and contractile function of stem cell-derived cardiomyocytes. PMID:26344757

  4. A K-Band Linear Phased Array Antenna Based on Ba(0.60)Sr(0.40)TiO3 Thin Film Phase Shifters

    NASA Technical Reports Server (NTRS)

    Romanofsky, R.; Bernhard, J.; Washington, G.; VanKeuls, F.; Miranda, F.; Cannedy, C.

    2000-01-01

    This paper summarizes the development of a 23.675 GHz linear 16-element scanning phased array antenna based on thin ferroelectric film coupled microstripline phase shifters and microstrip patch radiators.

  5. Uncooled Thermopile Infrared Detector Linear Arrays with Detectivity Greater Than 10(super script9) cmHZ(super script 1/2)/W

    NASA Technical Reports Server (NTRS)

    Foote, Marc C.; Jones, Eric W.; Caillat, Thierry

    1997-01-01

    We have fabricated 63-element linear arrays of micromachined thermopile infrared detectors on silicon substrates. Each detector consists of a suspended silicon nitride membrane with 11 thermocouples of sputtered Bi-Te and Bi-Sb-Te films.

  6. INTEGRATING A LINEAR INTERPOLATION FUNCTION ACROSS TRIANGULAR CELL BOUNDARIES

    SciTech Connect

    J. R. WISEMAN; J. S. BROCK

    2000-04-01

    Computational models of particle dynamics often exchange solution data with discretized continuum-fields using interpolation functions. These particle methods require a series expansion of the interpolation function for two purposes: numerical analysis used to establish the model's consistency and accuracy, and logical-coordinate evaluation used to locate particles within a grid. This report presents discrete-expansions for a linear interpolation function commonly used within triangular cell geometries. Discrete-expansions, unlike a Taylor's series, account for interpolation discontinuities across cell boundaries and, therefore, are valid throughout a discretized domain. Verification of linear discrete-expansions is demonstrated on a simple test problem.

  7. Simplified calculation of solar cell temperatures in terrestrial photovoltaic arrays

    NASA Astrophysics Data System (ADS)

    Ingersoll, J. G.

    1984-12-01

    A simplified algorithm to predict the average steady-state temperature of the solar cells in a photovoltaic array has been developed. The methodology can be applied to arrays on the roof (or walls) of buildings as well as on the ground. It is intended primarily for residential buildings, although it can be used for any type of building, and considers all four-array mounting systems (rack, stand-off, direct, and integral). Input parameters in this development include weather (insolation, ambient temperature, wind speed, humidity, and sky cloud cover), as well as building construction and operation characteristics. The photovoltaic array's geometrical, optical, and thermal properties are used in the analysis as well. Natural or forced convection under the solar panels and/or in the building attic below can also be accounted for by this model. The model has been partially verified against limited measured data and found to be in very good agreement for wind speeds of 1 m/s or more.

  8. Linear arrays of InGaAs/InP avalanche photodiodes for 1.0-1.7 micron

    NASA Technical Reports Server (NTRS)

    Ackley, D. E.; Hladky, J.; Lange, M. J.; Mason, S.; Erickson, G.; Olsen, G. H.; Ban, V. S.; Forrest, S. R.; Staller, C.

    1990-01-01

    Separate absorption and multiplication InGaAs/InP avalanche photodiodes (SAM-APDs) with a floating guard ring structure that is well-suited to array applications have been successfully demonstrated. Individual APDs have breakdown voltages greater than 80 V, multiplications over 40 at 100 nA dark current, and uniform spatial gain profiles. Uniform I-V characteristics and gains have been measured over linear dimensions as large as 1.2 cm. Gains over 10 at low multiplied dark currents were measured on 21 consecutive devices at the wafer level.

  9. Linear arrays of InGaAs/InP avalanche photodiodes for 1.0-1.7 micron

    NASA Technical Reports Server (NTRS)

    Ackley, D. E.; Hladky, J.; Lange, M. J.; Mason, S.; Erickson, G.; Olsen, G. H.; Ban, V. S.; Forrest, S. R.; Staller, C.

    1990-01-01

    Separate absorption and multiplication InGaAs/InP avalanche photodiodes (SAM-APDs) with a floating guard ring structure that is well-suited to array applications have been successfully demonstrated. Individual APDs have breakdown voltages greater than 80 V, multiplications over 40 at 100 nA dark current, and uniform spatial gain profiles. Uniform I-V characteristics and gains have been measured over linear dimensions as large as 1.2 cm. Gains over 10 at low multiplied dark currents were measured on 21 consecutive devices at the wafer level.

  10. Real-time photoacoustic tomograpghy using linear array probe and detection of line structure using Hough transform.

    PubMed

    Shin, Seung-Won; Park, Jaebyung; Shin, Dong Ho; Song, Chul-Gyu; Kim, Kyeong-Seop

    2015-01-01

    A real-time photoacoustic tomography (PAT) system is developed using a linear array probe and phantom images are acquired with a pattern of line structure. Moreover, it is attempted to detect line structures from the acquired images by Hough transform. This effort leads to the measurement of a process of magenta passing through a tube and acquisition of images at a speed of about 2 frame/sec. Besides, it is confirmed that the Hough transform applied on the acquired PAT images has the detection rate of about 50% for delineating a line structure.

  11. Linear array transducer for high-power airborne ultrasound using flextensional structure

    NASA Astrophysics Data System (ADS)

    Yamamoto, Jun; Mizuno, Yosuke; Tabaru, Marie; Nakamura, Kentaro

    2015-07-01

    To change the direction of ultrasonic irradiation without moving a transducer, a high-power airborne ultrasonic transducer for a one-dimensional phased array system was designed and tested. A flextensional element transducer with higher-mode bending vibration was fabricated to obtain a high vibration amplitude over a wide aperture, where a phase-compensating stepped structure was employed. The width of the main lobe at half maximum and the sidelobe level were measured to be 14.3 deg and 0.78, respectively. The maximal sound pressure of 132 dB (0 dB re. 0.02 mPa) was obtained under the applied voltage of 4.0 V. The beam steering characteristics of a phased array using eight elements were compared with the simple theory.

  12. Role of micropillar arrays in cell rolling dynamics.

    PubMed

    Kim, Kisoo; Koo, Junemo; Moon, SangJun; Lee, Won Gu

    2016-12-19

    In this study, we present a role of arrayed micropillar structures in cell rolling dynamics. Cell rolling on a ligand coated surface as a means of cell separation was demonstrated using a micropillar-integrated microfluidic channel. This approach allows the separation of cells according to characteristic surface properties, regardless of cell size. In these experiments, different moving trajectories of the cells between a ligand-coated micropost structure and a 1% BSA coated micropost structure were observed using sequential images. Based on the analysis of the angle of travel of cells in the trajectory, the average angles of travel on the ligand-coated microposts were 1.5° and -3.1° on a 1% BSA-coated micropost structure. The overall force equivalent applied to a cell can be analyzed to predict the cell rolling dynamics when a cell is detached. These results show that it will be possible to design chip geometry for delicate operations and to separate target cells. Furthermore, we believe that these control techniques based on a ligand coated micropillar surface can be used for enhancing cell rolling-based separation in a faster and more continuous manner.

  13. Comparison of real-time multiplex human papillomavirus (HPV) PCR assays with the linear array HPV genotyping PCR assay and influence of DNA extraction method on HPV detection.

    PubMed

    Roberts, Christine C; Swoyer, Ryan; Bryan, Janine T; Taddeo, Frank J

    2011-05-01

    Real-time human papillomavirus (HPV) type-specific multiplex PCR assays were developed to detect HPV DNA in specimens collected for the efficacy determination of the quadrivalent HPV (type 6, 11, 16, and 18) L1 virus-like particle (VLP) vaccine (Gardasil). We evaluated the concordance between type-specific multiplex HPV PCR and the widely used, commercially available Roche Linear Array genotyping PCR assay. Female genital swab specimens were tested for the presence of L1, E6, and E7 sequences of HPV type 6 (HPV6), HPV11, HPV16, HPV18, HPV31, HPV45, HPV52, and HPV58 and E6 and E7 sequences of HPV33, HPV35, HPV39, HPV51, HPV56, and HPV59 in type- and gene-specific real-time multiplex PCR assays. Specimens were also tested for the presence of L1 sequences using two versions of the Roche Linear Array genotyping assay. Measures of concordance of a modified version of the Linear Array and the standard Linear Array PCR assay were evaluated. With specimen DNA extraction using the Qiagen Spin blood kit held as the constant, multiplex PCR assays detect more HPV-positive specimens for the 14 HPV types common to both than either version of the Linear Array HPV genotyping assay. Type-specific agreements between the assays were good, at least 0.838, but were often driven by negative agreement in HPV types with low prevalence, as evidenced by reduced proportions of positive agreement. Overall HPV status agreements ranged from 0.615 for multiplex PCR and standard Linear Array to 0.881 for multiplex PCR and modified Linear Array. An alternate DNA extraction technique, that used by the Qiagen MinElute kit, impacted subsequent HPV detection in both the multiplex PCR and Linear Array assays.

  14. Development of a second-generation linear Fresnel lens photovoltaic and thermal (PVT) concentrator array, including fabrication and installation of a 200 square meter collector field

    SciTech Connect

    O'Neill, M.J.

    1985-02-01

    This report summarizes work performed in two areas: development of a second-generation linear Fresnel lens photovoltaic concentrator array, and development and fabrication of a 22 kilowatt photovoltaic and thermal concentrator array. Under these programs, ENTECH, Inc. developed a new second-generation linear Fresnel lens PVT concentrator system, and deployed a 200 square meter collector field of the new design at Sandia-Albuquerque. The new system combines excellent performance and low mass-production cost.

  15. Plasmonic hole arrays with extreme optical chirality in linear and nonlinear regimes

    NASA Astrophysics Data System (ADS)

    Gorkunov, Maxim V.; Kondratov, Alexei V.; Darinskii, Alexander N.; Artemov, Vladimir V.; Rogov, Oleg Y.; Gainutdinov, Radmir V.

    2016-04-01

    Metamaterials with high optical activity (OA) and circular dichroism (CD) are desired for various prospective applications ranging from circular light polarizing to enhanced chiral sensing and biosensing. Modern techniques allow fabricating subwavelength arrays of holes of complex chiral shapes that exhibit extreme optical chirality: their OA and CD take the whole range of possible values in the visible. In order to understand the nature of extreme chirality, we performed the electromagnetic finite difference time domain simulations for the hole shapes resolved by atomic force microscopy. The analysis of the simulation data allowed us to develop an analytical chiral coupled-mode model that nicely fits the results and explains the extreme chirality as determined by the Fano-type transmission resonance due to the interference of a weak background channel and a resonant plasmon channel. The model shows critical importance of the dissipation losses, the hole shape symmetry and chirality. In a planar 2D-chiral hole array, the mirror asymmetry can be induced by the difference of dielectric materials adjacent to the array sides and even their weak deviation results in remarkably strong OA and CD. We note that such deviations can arise due to the dielectric nonlinearity and discuss how 2D-chiral metamaterials in symmetric environment can acquire optical chirality due to the nonlinear symmetry breaking.

  16. Mechanical stress inference for two dimensional cell arrays.

    PubMed

    Chiou, Kevin K; Hufnagel, Lars; Shraiman, Boris I

    2012-01-01

    Many morphogenetic processes involve mechanical rearrangements of epithelial tissues that are driven by precisely regulated cytoskeletal forces and cell adhesion. The mechanical state of the cell and intercellular adhesion are not only the targets of regulation, but are themselves the likely signals that coordinate developmental process. Yet, because it is difficult to directly measure mechanical stress in vivo on sub-cellular scale, little is understood about the role of mechanics in development. Here we present an alternative approach which takes advantage of the recent progress in live imaging of morphogenetic processes and uses computational analysis of high resolution images of epithelial tissues to infer relative magnitude of forces acting within and between cells. We model intracellular stress in terms of bulk pressure and interfacial tension, allowing these parameters to vary from cell to cell and from interface to interface. Assuming that epithelial cell layers are close to mechanical equilibrium, we use the observed geometry of the two dimensional cell array to infer interfacial tensions and intracellular pressures. Here we present the mathematical formulation of the proposed Mechanical Inverse method and apply it to the analysis of epithelial cell layers observed at the onset of ventral furrow formation in the Drosophila embryo and in the process of hair-cell determination in the avian cochlea. The analysis reveals mechanical anisotropy in the former process and mechanical heterogeneity, correlated with cell differentiation, in the latter process. The proposed method opens a way for quantitative and detailed experimental tests of models of cell and tissue mechanics.

  17. Recent Advances in Genetic Technique of Microbial Report Cells and Their Applications in Cell Arrays

    PubMed Central

    Kim, Do Hyun; Kim, Moon Il; Park, Hyun Gyu

    2015-01-01

    Microbial cell arrays have attracted consistent attention for their ability to provide unique global data on target analytes at low cost, their capacity for readily detectable and robust cell growth in diverse environments, their high degree of convenience, and their capacity for multiplexing via incorporation of molecularly tailored reporter cells. To highlight recent progress in the field of microbial cell arrays, this review discusses research on genetic engineering of reporter cells, technologies for patterning live cells on solid surfaces, cellular immobilization in different polymers, and studies on their application in environmental monitoring, disease diagnostics, and other related fields. On the basis of these results, we discuss current challenges and future prospects for novel microbial cell arrays, which show promise for use as potent tools for unraveling complex biological processes. PMID:26436087

  18. Modeling Herriott cells using the linear canonical transform.

    PubMed

    Dahlen, Dar; Wilcox, Russell; Leemans, Wim

    2017-01-10

    We demonstrate a new way to analyze stable, multipass optical cavities (Herriott cells), using the linear canonical transform formalism, showing that re-entrant designs reproduce an arbitrary input field at the output, resulting in useful symmetries. We use this analysis to predict the stability of cavities used in interferometric delay lines for temporal pulse addition.

  19. Array-CGH analysis of cutaneous anaplastic large cell lymphoma.

    PubMed

    Szuhai, K; van Doorn, R; Tensen, C P; Van Kester

    2013-01-01

    This chapter describes a study in which the pattern of numerical chromosomal alterations in cutaneous anaplastic large cell lymphoma (C-ALCL) tumor samples was defined using array-based comparative genomic hybridization (CGH). First, the array-based CGH technique applied is outlined in detail. Next, its application in the analysis of C-ALCL tumor specimens is described. This approach resulted in the identification of highly recurrent chromosomal alterations in C-ALCL that include gain of 7q31 and loss on 6q16-6q21 and 13q34, each affecting 45% of the patients. The pattern characteristic of C-ALCL differs markedly from chromosomal alterations observed in other CTCL such as mycosis fungoides and Sézary syndrome and yielded several candidate genes with potential relevance in the pathogenesis of C-ALCL.

  20. Design and Information Content of Arrays of Sorption-based Vapor Sensors using Solubility Interactions and Linear Solvation Energy Relationships

    SciTech Connect

    Grate, Jay W.; Abraham, Michael H.; Wise, Barry M.

    2009-11-01

    The sorption of vapors by the selective polymeric layer on a chemical vapor sensor is described in detail and dissected into fundamental solubility interactions. The sorption process is modeled in terms of solvation parameters for vapor solubility properties and linear solvation energy relationships. The latter relationships model the log of the partition coefficient as the sum of terms related to specific types of interactions. The approaches are particularly applicable to the design and understanding of acoustic wave chemical vapor sensors such as those based on surface acoustic wave devices. It is shown how an understanding of solubility interactions informs the selection of polymers to obtain chemical diversity in sensor arrays and obtain the maximum amount of chemical information. The inherent dimensionality of the array data, as analyzed by principle components analysis, is consistent with this formulation. Furthermore, it is shown how new chemometric methods have been developed to extract the chemical information from array responses in terms of solvation parameters serving as de-scriptors of the detected vapor.

  1. Note: Design principles of a linear array multi-channel effusive metal-vapor atom source

    SciTech Connect

    Jana, B.; Majumder, A.; Thakur, K. B.; Das, A. K.

    2013-10-15

    Atomic beams can easily be produced by allowing atoms to effuse through a channel. In an earlier investigation [A. Majumder et al., Vacuum 83, 989 (2009)], we had designed, fabricated, and characterized an effusive metal-vapor source using collinear-array of multi-channel. In this note, we describe the theoretical basis of designing the source. Atom density in atomic beam has been estimated using a set of analytical expressions for long-channel operated in transparent mode. Parametric studies on aspect ratio of channel, inter-channel separation, beam width, and vertical distance from the source are carried out. They are useful in providing physical picture and optimizing design parameters.

  2. Re-evaluation of EMG-torque relation in chronic stroke using linear electrode array EMG recordings.

    PubMed

    Bhadane, Minal; Liu, Jie; Rymer, W Zev; Zhou, Ping; Li, Sheng

    2016-06-28

    The objective was to re-evaluate the controversial reports of EMG-torque relation between impaired and non-impaired sides using linear electrode array EMG recordings. Ten subjects with chronic stroke performed a series of submaximal isometric elbow flexion tasks. A 20-channel linear array was used to record surface EMG of the biceps brachii muscles from both impaired and non-impaired sides. M-wave recordings for bilateral biceps brachii muscles were also made. Distribution of the slope of the EMG-torque relations for the individual channels showed a quasi-symmetrical "M" shaped pattern. The lowest value corresponded to the innervation zone (IZ) location. The highest value from the slope curve for each side was selected for comparison to minimize the effect of electrode placement and IZ asymmetry. The slope was greater on the impaired side in 4 of 10 subjects. There were a weak correlation between slope ratio and strength ratio and a moderate to high correlation between slope ratio and M-wave ratio between two sides. These findings suggest that the EMG-torque relations are likely mediated and influenced by multiple factors. Our findings emphasize the importance of electrode placement and suggest the primary role of peripheral adaptive changes in the EMG-torque relations in chronic stroke.

  3. Experimental validation of spatial Fourier transform-based multiple sound zone generation with a linear loudspeaker array.

    PubMed

    Okamoto, Takuma; Sakaguchi, Atsushi

    2017-03-01

    Generating acoustically bright and dark zones using loudspeakers is gaining attention as one of the most important acoustic communication techniques for such uses as personal sound systems and multilingual guide services. Although most conventional methods are based on numerical solutions, an analytical approach based on the spatial Fourier transform with a linear loudspeaker array has been proposed, and its effectiveness has been compared with conventional acoustic energy difference maximization and presented by computer simulations. To describe the effectiveness of the proposal in actual environments, this paper investigates the experimental validation of the proposed approach with rectangular and Hann windows and compared it with three conventional methods: simple delay-and-sum beamforming, contrast maximization, and least squares-based pressure matching using an actually implemented linear array of 64 loudspeakers in an anechoic chamber. The results of both the computer simulations and the actual experiments show that the proposed approach with a Hann window more accurately controlled the bright and dark zones than the conventional methods.

  4. Development of high-speed InGaAs linear array and camera for OCT and machine vision

    NASA Astrophysics Data System (ADS)

    Malchow, Douglas S.; Brubaker, Robert M.; Nguyen, Hai; Flynn, Kevin

    2008-02-01

    Spectral Domain Optical Coherence Tomography (SD-OCT) is a rapidly growing imaging technique for high-resolution visualization of structures within strongly scattering media. It is being used to create 2-D and 3-D images in biological tissues to measure structures in the eye, image abnormal growths in organ tissue, and to assess the health of arterial walls. The ability to image to depths of several millimeters with resolutions better than 5 microns has driven the need to maximize the image depth, while also increasing the imaging speed. Researchers are using short-wave-infrared light wavelengths from 1 to 1.6 microns to penetrate deeper in denser tissue than visible or NIR wavelengths. This, in turn, has created the need to increase the line rates of InGaAs linear array cameras by a factor of ten, while also increasing gain and reducing dead time. This paper will describe the development and characterization of a 1024 pixel linear array with 25 micron pitch and readout rate of over 45,000 lines per second and the resulting camera. This camera will also have application for machine vision inspection of hot glass globs, for sorting of fast moving agricultural materials and for quality control of pharmaceutical products.

  5. Re-evaluation of EMG-torque relation in chronic stroke using linear electrode array EMG recordings

    PubMed Central

    Bhadane, Minal; Liu, Jie; Rymer, W. Zev; Zhou, Ping; Li, Sheng

    2016-01-01

    The objective was to re-evaluate the controversial reports of EMG-torque relation between impaired and non-impaired sides using linear electrode array EMG recordings. Ten subjects with chronic stroke performed a series of submaximal isometric elbow flexion tasks. A 20-channel linear array was used to record surface EMG of the biceps brachii muscles from both impaired and non-impaired sides. M-wave recordings for bilateral biceps brachii muscles were also made. Distribution of the slope of the EMG-torque relations for the individual channels showed a quasi-symmetrical “M” shaped pattern. The lowest value corresponded to the innervation zone (IZ) location. The highest value from the slope curve for each side was selected for comparison to minimize the effect of electrode placement and IZ asymmetry. The slope was greater on the impaired side in 4 of 10 subjects. There were a weak correlation between slope ratio and strength ratio and a moderate to high correlation between slope ratio and M-wave ratio between two sides. These findings suggest that the EMG-torque relations are likely mediated and influenced by multiple factors. Our findings emphasize the importance of electrode placement and suggest the primary role of peripheral adaptive changes in the EMG-torque relations in chronic stroke. PMID:27349938

  6. Solar cell array design handbook - The principles and technology of photovoltaic energy conversion

    NASA Technical Reports Server (NTRS)

    Rauschenbach, H. S.

    1980-01-01

    Photovoltaic solar cell array design and technology for ground-based and space applications are discussed from the user's point of view. Solar array systems are described, with attention given to array concepts, historical development, applications and performance, and the analysis of array characteristics, circuits, components, performance and reliability is examined. Aspects of solar cell array design considered include the design process, photovoltaic system and detailed array design, and the design of array thermal, radiation shielding and electromagnetic components. Attention is then given to the characteristics and design of the separate components of solar arrays, including the solar cells, optical elements and mechanical elements, and the fabrication, testing, environmental conditions and effects and material properties of arrays and their components are discussed.

  7. Properties of linear arrays of Josephson junctions capacitively coupled to a diffusive metal

    NASA Astrophysics Data System (ADS)

    Lobos, Alejandro; Giamarchi, Thierry

    2011-03-01

    Josephson junctions arrays (JJAs) are strongly-correlated quantum systems showing a rich and complex behavior at low-temperatures. Besides their potential uses in applications, JJAs allow to investigate (under controlled conditions) many aspects of low-dimensional superconductivity which remain to be understood. In this work we study the phase diagram and the low-energy properties of a one-dimensional (1D) JJA capacitively coupled to a diffusive two-dimensional electron gas (2DEG) placed at a distance d , which provides dissipation. We derive an effective field-theoretical model for the 1D JJA coupled to the 2DEG, and predict a superconductor-insulator transition (SIT) at T = 0 , in agreement with former theoretical predictions. We discuss implications for transport experiments and for the observed SIT in 1DJJAs. Both in the superconducting and insulating phases, the coupling to the 2DEG produces deviations with respect to the resistivity as a function of T predicted for an isolated array. This work was supported in part by the Swiss SNF under MaNEP and division II.

  8. Linear and Non-Linear Optical Imaging of Cancer Cells with Silicon Nanoparticles

    PubMed Central

    Tolstik, Elen; Osminkina, Liubov A.; Akimov, Denis; Gongalsky, Maksim B.; Kudryavtsev, Andrew A.; Timoshenko, Victor Yu.; Heintzmann, Rainer; Sivakov, Vladimir; Popp, Jürgen

    2016-01-01

    New approaches for visualisation of silicon nanoparticles (SiNPs) in cancer cells are realised by means of the linear and nonlinear optics in vitro. Aqueous colloidal solutions of SiNPs with sizes of about 10–40 nm obtained by ultrasound grinding of silicon nanowires were introduced into breast cancer cells (MCF-7 cell line). Further, the time-varying nanoparticles enclosed in cell structures were visualised by high-resolution structured illumination microscopy (HR-SIM) and micro-Raman spectroscopy. Additionally, the nonlinear optical methods of two-photon excited fluorescence (TPEF) and coherent anti-Stokes Raman scattering (CARS) with infrared laser excitation were applied to study the localisation of SiNPs in cells. Advantages of the nonlinear methods, such as rapid imaging, which prevents cells from overheating and larger penetration depth compared to the single-photon excited HR-SIM, are discussed. The obtained results reveal new perspectives of the multimodal visualisation and precise detection of the uptake of biodegradable non-toxic SiNPs by cancer cells and they are discussed in view of future applications for the optical diagnostics of cancer tumours. PMID:27626408

  9. Linear and Non-Linear Optical Imaging of Cancer Cells with Silicon Nanoparticles.

    PubMed

    Tolstik, Elen; Osminkina, Liubov A; Akimov, Denis; Gongalsky, Maksim B; Kudryavtsev, Andrew A; Timoshenko, Victor Yu; Heintzmann, Rainer; Sivakov, Vladimir; Popp, Jürgen

    2016-09-12

    New approaches for visualisation of silicon nanoparticles (SiNPs) in cancer cells are realised by means of the linear and nonlinear optics in vitro. Aqueous colloidal solutions of SiNPs with sizes of about 10-40 nm obtained by ultrasound grinding of silicon nanowires were introduced into breast cancer cells (MCF-7 cell line). Further, the time-varying nanoparticles enclosed in cell structures were visualised by high-resolution structured illumination microscopy (HR-SIM) and micro-Raman spectroscopy. Additionally, the nonlinear optical methods of two-photon excited fluorescence (TPEF) and coherent anti-Stokes Raman scattering (CARS) with infrared laser excitation were applied to study the localisation of SiNPs in cells. Advantages of the nonlinear methods, such as rapid imaging, which prevents cells from overheating and larger penetration depth compared to the single-photon excited HR-SIM, are discussed. The obtained results reveal new perspectives of the multimodal visualisation and precise detection of the uptake of biodegradable non-toxic SiNPs by cancer cells and they are discussed in view of future applications for the optical diagnostics of cancer tumours.

  10. Mixed Linear/Square-Root Encoded Single-Slope Ramp Provides Low-Noise ADC with High Linearity for Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Wrigley, Chris J.; Hancock, Bruce R.; Newton, Kenneth W.; Cunningham, Thomas J.

    2013-01-01

    Single-slope analog-to-digital converters (ADCs) are particularly useful for onchip digitization in focal plane arrays (FPAs) because of their inherent monotonicity, relative simplicity, and efficiency for column-parallel applications, but they are comparatively slow. Squareroot encoding can allow the number of code values to be reduced without loss of signal-to-noise ratio (SNR) by keeping the quantization noise just below the signal shot noise. This encoding can be implemented directly by using a quadratic ramp. The reduction in the number of code values can substantially increase the quantization speed. However, in an FPA, the fixed pattern noise (FPN) limits the use of small quantization steps at low signal levels. If the zero-point is adjusted so that the lowest column is onscale, the other columns, including those at the center of the distribution, will be pushed up the ramp where the quantization noise is higher. Additionally, the finite frequency response of the ramp buffer amplifier and the comparator distort the shape of the ramp, so that the effective ramp value at the time the comparator trips differs from the intended value, resulting in errors. Allowing increased settling time decreases the quantization speed, while increasing the bandwidth increases the noise. The FPN problem is solved by breaking the ramp into two portions, with some fraction of the available code values allocated to a linear ramp and the remainder to a quadratic ramp. To avoid large transients, both the value and the slope of the linear and quadratic portions should be equal where they join. The span of the linear portion must cover the minimum offset, but not necessarily the maximum, since the fraction of the pixels above the upper limit will still be correctly quantized, albeit with increased quantization noise. The required linear span, maximum signal and ratio of quantization noise to shot noise at high signal, along with the continuity requirement, determines the number of

  11. An approach for configuring space photovoltaic tandem arrays based on cell layer performance

    NASA Technical Reports Server (NTRS)

    Flora, C. S.; Dillard, P. A.

    1991-01-01

    Meeting solar array performance goals of 300 W/Kg requires use of solar cells with orbital efficiencies greater than 20 percent. Only multijunction cells and cell layers operating in tandem produce this required efficiency. An approach for defining solar array design concepts that use tandem cell layers involve the following: transforming cell layer performance at standard test conditions to on-orbit performance; optimizing circuit configuration with tandem cell layers; evaluating circuit sensitivity to cell current mismatch; developing array electrical design around selected circuit; and predicting array orbital performance including seasonal variations.

  12. Linear diode laser bar optical stretchers for cell deformation

    PubMed Central

    Sraj, Ihab; Marr, David W.M.; Eggleton, Charles D.

    2010-01-01

    To investigate the use of linear diode laser bars to optically stretch cells and measure their mechanical properties, we present numerical simulations using the immersed boundary method (IBM) coupled with classic ray optics. Cells are considered as three-dimensional (3D) spherical elastic capsules immersed in a fluid subjected to both optical and hydrodynamic forces in a periodic domain. We simulate cell deformation induced by both single and dual diode laser bar configurations and show that a single diode laser bar induces significant stretching but also induces cell translation of speed < 10 µm/sec for applied 6.6 mW/µm power in unconfined systems. The dual diode laser bar configuration, however, can be used to both stretch and optically trap cells at a fixed position. The net cell deformation was found to be a function of the total laser power and not the power distribution between single or dual diode laser bar configurations. PMID:21258483

  13. Study of cell secretion using MEMS-based arrays

    NASA Astrophysics Data System (ADS)

    Feng, Xiaojun; Szaro, Ben G.; Castracane, James

    2004-01-01

    This paper focuses on the development of a custom MEMS-based array which will facilitate cell secretion studies by enabling parallel electrochemical detection of secretion events from separate cells with millisecond resolution. Initial prototypes of the microarrays have been fabricated with well-shaped gold electrodes which roughly conform to the shape of a single cell. Amperometric measurements on bovine adrenal chromaffin cells using the prototype microarrays concluded that 80% of the catecholamine secreted from the cells was captured by the well-electrodes. This was a 4-fold increase in detection efficiency over the conventional carbon fiber electrode method. To expand the applicability of this method, additional cell-lines and microarray designs are under investigation. An amphibian fibroblast cell-line (FT cell-line, American Tissue Culture Collection) is being used in our lab. FT cells can take up hormones or other biological compounds from the culture media through a non-specific uptake mechanism which is still under investigation. Microarrays of a new design have been fabricated with patterned gold electrodes on polyimide. A different testing method will be applied to these new microarrays. The FT cells will be cultured directly on top of the microarrays to cover the gold electrodes. Cells will then be loaded with norepinephrine by incubation in media containing 1mM norepinephrine. Rapid elevation of intracellular Ca2+ levels triggers the exocytosis of norepinephrine which then can be detected by the gold electrode. The new polyimide based microarrays have been successfully used to support confluent growth of the FT cells. Loading of the FT cells with norepinephrine and electrochemical detection tests are underway.

  14. Study of cell secretion using MEMS-based arrays

    NASA Astrophysics Data System (ADS)

    Feng, Xiaojun; Szaro, Ben G.; Castracane, James

    2003-12-01

    This paper focuses on the development of a custom MEMS-based array which will facilitate cell secretion studies by enabling parallel electrochemical detection of secretion events from separate cells with millisecond resolution. Initial prototypes of the microarrays have been fabricated with well-shaped gold electrodes which roughly conform to the shape of a single cell. Amperometric measurements on bovine adrenal chromaffin cells using the prototype microarrays concluded that 80% of the catecholamine secreted from the cells was captured by the well-electrodes. This was a 4-fold increase in detection efficiency over the conventional carbon fiber electrode method. To expand the applicability of this method, additional cell-lines and microarray designs are under investigation. An amphibian fibroblast cell-line (FT cell-line, American Tissue Culture Collection) is being used in our lab. FT cells can take up hormones or other biological compounds from the culture media through a non-specific uptake mechanism which is still under investigation. Microarrays of a new design have been fabricated with patterned gold electrodes on polyimide. A different testing method will be applied to these new microarrays. The FT cells will be cultured directly on top of the microarrays to cover the gold electrodes. Cells will then be loaded with norepinephrine by incubation in media containing 1mM norepinephrine. Rapid elevation of intracellular Ca2+ levels triggers the exocytosis of norepinephrine which then can be detected by the gold electrode. The new polyimide based microarrays have been successfully used to support confluent growth of the FT cells. Loading of the FT cells with norepinephrine and electrochemical detection tests are underway.

  15. Low power, highly linear output buffer. [for infrared focal plane arrays

    NASA Technical Reports Server (NTRS)

    Foley, D.; Butler, N.; Stobie, J.

    1992-01-01

    A class AB CMOS output buffer has been designed for use on an IR focal plane array. Given the requirements for power dissipation and load capacitance a class A output, such as a source follower, would be unsuitable. The approach taken uses a class AB amplifier configured as a charge integrator. Thus it converts a charge packet in the focal plane multiplexer to a voltage which is then the output of the focal plane. With a quiescent current of 18 micro-a and a load capacitance of 100 pf, the amplifier has an open loop unity gain bandwidth of 900 khz. Integral nonlinearity is better than .03 percent over 5.5 volts when run with VDD-VSS = 6v.

  16. Low power, highly linear output buffer. [for infrared focal plane arrays

    NASA Technical Reports Server (NTRS)

    Foley, D.; Butler, N.; Stobie, J.

    1992-01-01

    A class AB CMOS output buffer has been designed for use on an IR focal plane array. Given the requirements for power dissipation and load capacitance a class A output, such as a source follower, would be unsuitable. The approach taken uses a class AB amplifier configured as a charge integrator. Thus it converts a charge packet in the focal plane multiplexer to a voltage which is then the output of the focal plane. With a quiescent current of 18 micro-a and a load capacitance of 100 pf, the amplifier has an open loop unity gain bandwidth of 900 khz. Integral nonlinearity is better than .03 percent over 5.5 volts when run with VDD-VSS = 6v.

  17. Efficient Multiterminal Spectrum Splitting via a Nanowire Array Solar Cell

    PubMed Central

    2015-01-01

    Nanowire-based solar cells opened a new avenue for increasing conversion efficiency and rationalizing material use by growing different III–V materials on silicon substrates. Here, we propose a multiterminal nanowire solar cell design with a theoretical conversion efficiency of 48.3% utilizing an efficient lateral spectrum splitting between three different III–V material nanowire arrays grown on a flat silicon substrate. This allows choosing an ideal material combination to achieve the proper spectrum splitting as well as fabrication feasibility. The high efficiency is possible due to an enhanced absorption cross-section of standing nanowires and optimization of the geometric parameters. Furthermore, we propose a multiterminal contacting scheme that can be fabricated with a technology close to standard CMOS. As an alternative we also consider a single power source with a module level voltage matching. These new concepts open avenues for next-generation solar cells for terrestrial and space applications. PMID:26878027

  18. Efficient Multiterminal Spectrum Splitting via a Nanowire Array Solar Cell.

    PubMed

    Dorodnyy, Alexander; Alarcon-Lladó, Esther; Shklover, Valery; Hafner, Christian; Fontcuberta I Morral, Anna; Leuthold, Juerg

    2015-09-16

    Nanowire-based solar cells opened a new avenue for increasing conversion efficiency and rationalizing material use by growing different III-V materials on silicon substrates. Here, we propose a multiterminal nanowire solar cell design with a theoretical conversion efficiency of 48.3% utilizing an efficient lateral spectrum splitting between three different III-V material nanowire arrays grown on a flat silicon substrate. This allows choosing an ideal material combination to achieve the proper spectrum splitting as well as fabrication feasibility. The high efficiency is possible due to an enhanced absorption cross-section of standing nanowires and optimization of the geometric parameters. Furthermore, we propose a multiterminal contacting scheme that can be fabricated with a technology close to standard CMOS. As an alternative we also consider a single power source with a module level voltage matching. These new concepts open avenues for next-generation solar cells for terrestrial and space applications.

  19. Inkjet printing of silk nest arrays for cell hosting.

    PubMed

    Suntivich, Rattanon; Drachuk, Irina; Calabrese, Rossella; Kaplan, David L; Tsukruk, Vladimir V

    2014-04-14

    An inkjet printing approach is presented for the facile fabrication of microscopic arrays of biocompatible silk "nests" capable of hosting live cells for prospective biosensors. The patterning of silk fibroin nests were constructed by the layer-by-layer (LbL) assembly of silk polyelectrolytes chemically modified with poly-(l-lysine) and poly-(l-glutamic acid) side chains. The inkjet-printed silk circular regions with a characteristic "nest" shape had diameters of 70-100 μm and a thickness several hundred nanometers were stabilized by ionic pairing and by the formation of the silk II crystalline secondary structure. These "locked-in" silk nests remained anchored to the substrate during incubation in cell growth media to provide a biotemplated platform for printing-in, immobilization, encapsulation and growth of cells. The process of inkjet-assisted printing is versatile and can be applied on any type of substrate, including rigid and flexible, with scalability and facile formation.

  20. Continuous perfusion microfluidic cell culture array for high-throughput cell-based assays.

    PubMed

    Hung, Paul J; Lee, Philip J; Sabounchi, Poorya; Lin, Robert; Lee, Luke P

    2005-01-05

    We present for the first time a microfluidic cell culture array for long-term cellular monitoring. The 10 x 10 array could potentially assay 100 different cell-based experiments in parallel. The device was designed to integrate the processes used in typical cell culture experiments on a single self-contained microfluidic system. Major functions include repeated cell growth/passage cycles, reagent introduction, and real-time optical analysis. The single unit of the array consists of a circular microfluidic chamber, multiple narrow perfusion channels surrounding the main chamber, and four ports for fluidic access. Human carcinoma (HeLa) cells were cultured inside the device with continuous perfusion of medium at 37 degrees C. The observed doubling time was 1.4 +/- 0.1 days with a peak cell density of approximately 2.5*10(5) cells/cm(2). Cell assay was demonstrated by monitoring the fluorescence localization of calcein AM from 1 min to 10 days after reagent introduction. Confluent cell cultures were passaged within the microfluidic chambers using trypsin and successfully regrown, suggesting a stable culture environment suitable for continuous operation. The cell culture array could offer a platform for a wide range of assays with applications in drug screening, bioinformatics, and quantitative cell biology. (c) 2004 Wiley Periodicals, Inc.

  1. Stoichiometric control of live cell mixing to enable fluidically-encoded co-culture models in perfused microbioreactor arrays.

    PubMed

    Occhetta, P; Glass, N; Otte, E; Rasponi, M; Cooper-White, J J

    2016-02-01

    In vivo, tissues are maintained and repaired through interactions between the present (different) cell types, which communicate with each other through both the secretion of paracrine factors and direct cell-cell contacts. In order to investigate and better understand this dynamic, complex interplay among diverse cell populations, we must develop new in vitro co-culture strategies that enable us to recapitulate such native tissue complexity. In this work, a microfluidic mixer based on a staggered herringbone design was computationally designed and experimentally validated that features the ability to mix large, non-diffusive particles (i.e. live cells) in a programmed manner. This is the first time that the herringbone mixer concept has been shown to effectively mix particles of the size range applicable to live cells. The cell mixer allowed for sequentially mixing of two cell types to generate reverse linear concentration co-culture patterns. Once validated, the mixer was integrated into a perfused microbioreactor array as an upstream module to deliver mixed cells to five downstream culture units, each consisting of ten serially-connected circular microculture chambers. This novel cell mixer microbioreactor array (CM-MBA) platform was validated through the establishment of spatio-temporally tunable osteogenic co-culture models, investigating the role of pre-osteoblastic cells (SAOS2) on human mesenchymal stem cells (hMSCs) commitment to an osteogenic endpoint. An increase on expression of alkaline phosphatase in sequential (downstream) chambers, consistent with the initial linear distribution of SAOS2, suggests not only osteoblastic cell-driven hMSCs induction towards the osteogenic phenotype, but also the importance of paracrine signaling. In conclusion, the cell mixer microbioreactor array combines the ability to rapidly establish cell co-culture models in a high-throughput, programmable fashion, with the additional advantage of maintaining cells in culture

  2. Distributed hydrophone array based on liquid crystal cell

    NASA Astrophysics Data System (ADS)

    Brodzeli, Zourab; Ladouceur, Francois; Silvestri, Leonardo; Michie, Andrew; Chigrinov, Vladimir; Guo, Grace Qi; Pozhidaev, Eugene P.; Kiselev, Alexei D.

    2012-02-01

    We describe a fibre optic hydrophone array system that could be used for underwater acoustic surveillance applications e.g. military, counter terrorist and customs authorities in protecting ports and harbors, offshore production facilities or coastal approaches as well as various marine applications. In this paper we propose a new approach to underwater sonar systems using voltage-controlled Liquid Crystals (LC) and simple multiplexing method. The proposed method permits measurements of sound under water at multiple points along an optical fibre using low cost components (LC cells), standard single mode fibre, without complex interferometric measurement techniques, electronics or demodulation software.

  3. Radial microwire array solar cell with pyramidal structure

    NASA Astrophysics Data System (ADS)

    Priyadarshini, Bindu; Das, Mukul Kumar; Sen, Mrinal; Kumar, Subindu

    2016-10-01

    In this work, a theoretical model for radial p-n junction microwire array solar cell with pyramidal structures in the space between microwires has been developed. Incorporation of pyramidal structures results in reflection of light, which would otherwise be unused, and illuminates side walls of the microwires. This additional illumination enhances absorption and, hence, efficiency of the whole structure. Efficiency enhancement is analyzed by varying different device parameters e.g., radius and length of each microwire and packing fraction of the structure. Results show that the maximum fractional efficiency enhancement can be obtained as 30% by suitable choice of these parameters.

  4. Linear Basal cell carcinoma in an asian patient.

    PubMed

    Shinsuke, Kinoshita; Hirohiko, Kakizaki; Yasuhiro, Takahashi; Kazuo, Hara; Masayoshi, Iwaki

    2007-12-17

    Linear basal cell carcinoma (BCC), which has a ratio of its long and short axes of more than 3: 1, is a distinct clinical entity among BCC. We report the first case report of a linear BCC in an Asian patient. An 87 year-old woman presented with an ulcerated black nodule, 15x5mm (3: 1), on her nasojungal fold of the right lower eyelid. The tumor was excised with 5 mm safety margin. The pathological examination confirmed the tumor was a BCC with a clear margin. Diagnosis of a linear BCC is based on its morphological features and occurrence along the wrinkle line, which needs to be also considered in Asian.

  5. Linear Basal Cell Carcinoma in an Asian Patient

    PubMed Central

    Shinsuke, Kinoshita; Hirohiko, Kakizaki; Yasuhiro, Takahashi; Kazuo, Hara; Masayoshi, Iwaki

    2007-01-01

    Linear basal cell carcinoma (BCC), which has a ratio of its long and short axes of more than 3: 1, is a distinct clinical entity among BCC. We report the first case report of a linear BCC in an Asian patient. An 87 year-old woman presented with an ulcerated black nodule, 15×5mm (3: 1), on her nasojungal fold of the right lower eyelid. The tumor was excised with 5 mm safety margin. The pathological examination confirmed the tumor was a BCC with a clear margin. Diagnosis of a linear BCC is based on its morphological features and occurrence along the wrinkle line, which needs to be also considered in Asian. PMID:19478861

  6. Demonstration of a linear optical true-time delay device by use of a microelectromechanical mirror array.

    PubMed

    Rader, Amber; Anderson, Betty Lise

    2003-03-10

    We present the design and proof-of-concept demonstration of an optical device capable of producing true-time delay(s) (TTD)(s) for phased array antennas. This TTD device uses a free-space approach consisting of a single microelectromechanical systems (MEMS) mirror array in a multiple reflection spherical mirror configuration based on the White cell. Divergence is avoided by periodic refocusing by the mirrors. By using the MEMS mirror to switch between paths of different lengths, time delays are generated. Six different delays in 1-ns increments were demonstrated by using the Texas Instruments Digital Micromirror Device as the switching element. Losses of 1.6 to 5.2 dB per bounce and crosstalk of -27 dB were also measured, both resulting primarily from diffraction from holes in each pixel and the inter-pixel gaps of the MEMS.

  7. Bipolar Electrode Array Embedded in a Polymer Light-Emitting Electrochemical Cell.

    PubMed

    Gao, Jun; Chen, Shulun; AlTal, Faleh; Hu, Shiyu; Bouffier, Laurent; Wantz, Guillaume

    2017-09-20

    A linear array of aluminum discs is deposited between the driving electrodes of an extremely large planar polymer light-emitting electrochemical cell (PLEC). The planar PLEC is then operated at a constant bias voltage of 100 V. This promotes in situ electrochemical doping of the luminescent polymer from both the driving electrodes and the aluminum discs. These aluminum discs function as discrete bipolar electrodes (BPEs) that can drive redox reactions at their extremities. Time-lapse fluorescence imaging reveals that p- and n-doping that originated from neighboring BPEs can interact to form multiple light-emitting p-n junctions in series. This provides direct evidence of the working principle of bulk homojunction PLECs. The propagation of p-doping is faster from the BPEs than from the positive driving electrode due to electric field enhancement at the extremities of BPEs. The effect of field enhancement and the fact that the doping fronts only need to travel the distance between the neighboring BPEs to form a light-emitting junction greatly reduce the response time for electroluminescence in the region containing the BPE array. The near simultaneous formation of multiple light-emitting p-n junctions in series causes a measurable increase in cell current. This indicates that the region containing a BPE is much more conductive than the rest of the planar cell despite the latter's greater width. The p- and n-doping originating from the BPEs is initially highly confined. Significant expansion and divergence of doping occurred when the region containing the BPE array became more conductive. The shape and direction of expanded doping strongly suggest that the multiple light-emitting p-n junctions, formed between and connected by the array of metal BPEs, have functioned as a single rod-shaped BPE. This represents a new type of BPE that is formed in situ and as a combination of metal, doped polymers, and forward-biased p-n junctions connected in series.

  8. PARALIND-based blind joint angle and delay estimation for multipath signals with uniform linear array

    NASA Astrophysics Data System (ADS)

    Liu, Xu; Guang, Liang; Yang, Longxiang; Zhu, Hongbo

    2012-12-01

    A novel joint angle and delay estimation (JADE) algorithm for multipath signals, based on the PARAllel profiles with LINear Dependencies (PARALIND) model, is proposed. Capitalizing on the structure property of Vandermonde matrices, PARALIND model is proved to be unique. Angle and delay of multiple rays of sources can be estimated by PARALIND decomposition and an ESPRIT-like shift-invariance technique. Simulation results show that the proposed algorithm outperforms the traditional JADE algorithm. It can automatically distinguish the estimated parameters between sources, and still be available when the number of rays is larger than the number of receiving antennae.

  9. Generating Non-Linear Concentration Gradients in Microfluidic Devices for Cell Studies

    PubMed Central

    Selimović, Šeila; Sim, Woo Young; Kim, Sang Bok; Jang, Yun Ho; Lee, Won Gu; Khabiry, Masoud; Bae, Hojae; Jambovane, Sachin; Hong, Jong Wook; Khademhosseini, Ali

    2011-01-01

    We describe a microfluidic device for generating non-linear (exponential and sigmoidal) concentration gradients, coupled with a microwell array for cell storage and analysis. The device has two inputs for co-flowing multiple aqueous solutions, a main co-flow channel and an asymmetrical grid of fluidic channels that allows the two solutions to combine at intersection points without fully mixing. Due to this asymmetry and diffusion of the two species in the co-flow channel, varying amounts of the two solutions enter each fluidic path. This induces exponential and sigmoidal concentration gradients at low and high flow rates, respectively, making the microfluidic device versatile. A key feature of this design is that it is space-saving, as it does not require multiplexing or a separate array of mixing channels. Furthermore, the gradient structure can be utilized in concert with cell experiments, to expose cells captured in microwells to various concentrations of soluble factors. We demonstrate the utility of this design to assess the viability of fibroblast cells in response to a range of hydrogen peroxide (H2O2) concentrations. PMID:21344866

  10. Precision Pointing in Space Using Arrays of Shape Memory Based Linear Actuators

    NASA Astrophysics Data System (ADS)

    Sonawane, Nikhil

    Space systems such as communication satellites, earth observation satellites and telescope require accurate pointing to observe fixed targets over prolonged time. These systems typically use reaction wheels to slew the spacecraft and gimballing systems containing motors to achieve precise pointing. Motor based actuators have limited life as they contain moving parts that require lubrication in space. Alternate methods have utilized piezoelectric actuators. This paper presents Shape memory alloys (SMA) actuators for control of a deployable antenna placed on a satellite. The SMAs are operated as a series of distributed linear actuators. These distributed linear actuators are not prone to single point failures and although each individual actuator is imprecise due to hysteresis and temperature variation, the system as a whole achieves reliable results. The SMAs can be programmed to perform a series of periodic motion and operate as a mechanical guidance system that is not prone to damage from radiation or space weather. Efforts are focused on developing a system that can achieve 1 degree pointing accuracy at first, with an ultimate goal of achieving a few arc seconds accuracy. Bench top model of the actuator system has been developed and working towards testing the system under vacuum. A demonstration flight of the technology is planned aboard a CubeSat.

  11. Feedback Linearized Aircraft Control Using Dynamic Cell Structure

    NASA Technical Reports Server (NTRS)

    Jorgensen, C. C.

    1998-01-01

    A Dynamic Cell Structure (DCS ) Neural Network was developed which learns a topology representing network (TRN) of F-15 aircraft aerodynamic stability and control derivatives. The network is combined with a feedback linearized tracking controller to produce a robust control architecture capable of handling multiple accident and off-nominal flight scenarios. This paper describes network and its performance for accident scenarios including differential stabilator lock, soft sensor failure, control, stability derivative variation, and turbulence.

  12. Electrophysiological characterization of Nsc-34 cell line using Microelectrode Array.

    PubMed

    Sabitha, K R; Sanjay, D; Savita, B; Raju, T R; Laxmi, T R

    2016-11-15

    Neurons communicate with each other through intricate network to evolve higher brain functions. The electrical activity of the neurons plays a crucial role in shaping the connectivity. With motor neurons being vulnerable to neurodegenerative diseases, understanding the electrophysiological properties of motor neurons is the need of the hour, in order to comprehend the impairment of connectivity in these diseases. NSC-34 cell line serves as an excellent model to study the properties of motor neurons as they express Choline acetyltransferase (ChAT). Although NSC-34 cell lines have been used to study the effect of various toxicological, neurotrophic and neuroprotective agents, the electrical activity of these cells has not been elucidated. In the current study, we have characterized the electrophysiological properties of NSC-34 cell lines using Micro-Electrode Array (MEA) as a tool. Based on the spike waveform, firing frequency, auto- and cross-correlogram analysis, we demonstrate that NSC-34 cell culture has >2 distinct types of neuronal population: principal excitatory neurons, putative interneurons and unclassified neurons. The presence of interneurons in the NSC-34 culture was characterized by increased expression of GAD-67 markers. Thus, finding an understanding of the electrophysiological properties of different population of neurons in NSC-34 cell line, will have multiple applications in the treatment of neurological disorders.

  13. Inverted Silicon Nanopencil Array Solar Cells with Enhanced Contact Structures.

    PubMed

    Liang, Xiaoguang; Shu, Lei; Lin, Hao; Fang, Ming; Zhang, Heng; Dong, Guofa; Yip, SenPo; Xiu, Fei; Ho, Johnny C

    2016-09-27

    Although three-dimensional nanostructured solar cells have attracted extensive research attention due to their superior broadband and omnidirectional light-harvesting properties, majority of them are still suffered from complicated fabrication processes as well as disappointed photovoltaic performances. Here, we employed our newly-developed, low-cost and simple wet anisotropic etching to fabricate hierarchical silicon nanostructured arrays with different solar cell contact design, followed by systematic investigations of their photovoltaic characteristics. Specifically, nano-arrays with the tapered tips (e.g. inverted nanopencils) are found to enable the more conformal top electrode deposition directly onto the nanostructures for better series and shunt conductance, but its insufficient film coverage at the basal plane would still restrict the charge carrier collection. In contrast, the low-platform contact design facilitates a substantial photovoltaic device performance enhancement of ~24%, as compared to the one of conventional top electrode design, due to the shortened current path and improved lateral conductance for the minimized carrier recombination and series resistance. This enhanced contact structure can not only maintain excellent photon-trapping behaviors of nanostructures, but also help to eliminate adverse impacts of these tapered nano-morphological features on the contact resistance, providing further insight into design consideration in optimizing the contact geometry for high-performance nanostructured photovoltaic devices.

  14. Inverted Silicon Nanopencil Array Solar Cells with Enhanced Contact Structures

    NASA Astrophysics Data System (ADS)

    Liang, Xiaoguang; Shu, Lei; Lin, Hao; Fang, Ming; Zhang, Heng; Dong, Guofa; Yip, Senpo; Xiu, Fei; Ho, Johnny C.

    2016-09-01

    Although three-dimensional nanostructured solar cells have attracted extensive research attention due to their superior broadband and omnidirectional light-harvesting properties, majority of them are still suffered from complicated fabrication processes as well as disappointed photovoltaic performances. Here, we employed our newly-developed, low-cost and simple wet anisotropic etching to fabricate hierarchical silicon nanostructured arrays with different solar cell contact design, followed by systematic investigations of their photovoltaic characteristics. Specifically, nano-arrays with the tapered tips (e.g. inverted nanopencils) are found to enable the more conformal top electrode deposition directly onto the nanostructures for better series and shunt conductance, but its insufficient film coverage at the basal plane would still restrict the charge carrier collection. In contrast, the low-platform contact design facilitates a substantial photovoltaic device performance enhancement of ~24%, as compared to the one of conventional top electrode design, due to the shortened current path and improved lateral conductance for the minimized carrier recombination and series resistance. This enhanced contact structure can not only maintain excellent photon-trapping behaviors of nanostructures, but also help to eliminate adverse impacts of these tapered nano-morphological features on the contact resistance, providing further insight into design consideration in optimizing the contact geometry for high-performance nanostructured photovoltaic devices.

  15. Inverted Silicon Nanopencil Array Solar Cells with Enhanced Contact Structures

    PubMed Central

    Liang, Xiaoguang; Shu, Lei; Lin, Hao; Fang, Ming; Zhang, Heng; Dong, Guofa; Yip, SenPo; Xiu, Fei; Ho, Johnny C.

    2016-01-01

    Although three-dimensional nanostructured solar cells have attracted extensive research attention due to their superior broadband and omnidirectional light-harvesting properties, majority of them are still suffered from complicated fabrication processes as well as disappointed photovoltaic performances. Here, we employed our newly-developed, low-cost and simple wet anisotropic etching to fabricate hierarchical silicon nanostructured arrays with different solar cell contact design, followed by systematic investigations of their photovoltaic characteristics. Specifically, nano-arrays with the tapered tips (e.g. inverted nanopencils) are found to enable the more conformal top electrode deposition directly onto the nanostructures for better series and shunt conductance, but its insufficient film coverage at the basal plane would still restrict the charge carrier collection. In contrast, the low-platform contact design facilitates a substantial photovoltaic device performance enhancement of ~24%, as compared to the one of conventional top electrode design, due to the shortened current path and improved lateral conductance for the minimized carrier recombination and series resistance. This enhanced contact structure can not only maintain excellent photon-trapping behaviors of nanostructures, but also help to eliminate adverse impacts of these tapered nano-morphological features on the contact resistance, providing further insight into design consideration in optimizing the contact geometry for high-performance nanostructured photovoltaic devices. PMID:27671709

  16. Analytical and Experimental Characterization of a Linear-Array Thermopile Scanning Radiometer for Geo-Synchronous Earth Radiation Budget Applications

    NASA Technical Reports Server (NTRS)

    Sorensen, Ira J.

    1998-01-01

    The Thermal Radiation Group, a laboratory in the department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently working towards the development of a new technology for cavity-based radiometers. The radiometer consists of a 256-element linear-array thermopile detector mounted on the wall of a mirrored wedgeshaped cavity. The objective of this research is to provide analytical and experimental characterization of the proposed radiometer. A dynamic end-to-end opto-electrothermal model is developed to simulate the performance of the radiometer. Experimental results for prototype thermopile detectors are included. Also presented is the concept of the discrete Green's function to characterize the optical scattering of radiant energy in the cavity, along with a data-processing algorithm to correct for the scattering. Finally, a parametric study of the sensitivity of the discrete Green's function to uncertainties in the surface properties of the cavity is presented.

  17. Automating the design of image processing pipelines for novel color filter arrays: local, linear, learned (L3) method

    NASA Astrophysics Data System (ADS)

    Tian, Qiyuan; Lansel, Steven; Farrell, Joyce E.; Wandell, Brian A.

    2014-03-01

    The high density of pixels in modern color sensors provides an opportunity to experiment with new color filter array (CFA) designs. A significant bottleneck in evaluating new designs is the need to create demosaicking, denoising and color transform algorithms tuned for the CFA. To address this issue, we developed a method(local, linear, learned or L3) for automatically creating an image processing pipeline. In this paper we describe the L3 algorithm and illustrate how we created a pipeline for a CFA organized as a 2×2 RGB/Wblock containing a clear (W) pixel. Under low light conditions, the L3 pipeline developed for the RGB/W CFA produces images that are superior to those from a matched Bayer RGB sensor. We also use L3 to learn pipelines for other RGB/W CFAs with different spatial layouts. The L3 algorithm shortens the development time for producing a high quality image pipeline for novel CFA designs.

  18. Linearly enhanced response of thermopower in cascaded array of dual-stripe single-metal thermocouples

    NASA Astrophysics Data System (ADS)

    Li, Gang; Han, Danhong; Yang, Fan; Wang, Zhenhai; Pi, Yudan; Wang, Wei; Xu, Shengyong

    2017-05-01

    Based on the width dependence of thermopower, cascaded single-metal thermocouples were demonstrated in this report. The cascaded thermocouples were made from 100 nm thick Ni films with a 100 μm wide stripe and a 5 μm narrow stripe. The experiment results showed a linearly enhanced response of thermopower. The 64-cascaded thermocouple achieved an equivalent Seebeck coefficient of up to 55.69 μV/K, which is higher than that of a commercial type-K thermocouple (39.6 μV/K). The single-metal thermocouples were also fabricated on flexible substrates. With the simple fabrication process and remarkable temperature sensing ability, the cascaded single-metal thermocouples may find promising applications in temperature measurement of modern flexible electronic products and wearable devices.

  19. On the retrieval of attenuation and site amplifications from ambient noise on linear arrays: further numerical simulations

    NASA Astrophysics Data System (ADS)

    Weaver, Richard L.

    2013-06-01

    While it is clear that ambient noise correlations contain information on seismic attenuation, retrieval of that information requires disentangling the influences of site amplification factors and anisotropic noise intensity. Recent work has argued that recognition that ambient noise intensity is governed by a radiative transfer equation will facilitate that retrieval. This sufficiently constrains the noise field to permit amplitudes of noise correlation waveforms to be fit to models of spatially varying attenuation, noise intensity and site amplification factors. Numerical simulations, for the case of a uniformly spaced linear array of receivers, homogeneous attenuation and wave speed and mild directionality to the noise field, were shown earlier to be consistent with the assertion. Here, the numerical simulations are extended to a broader class of systems. Accurate retrieval is demonstrated using a priori error estimates and weighted least-squares fitting. Attenuations and site factors are retrieved in systems with spatially varying attenuation, highly directional noise intensities, irregular line arrays and poor signal-to-noise ratios. Examination of a variety of systems illustrates some of the range of applicability and limits of the approach.

  20. Linear terrestrial laser scanning using array avalanche photodiodes as detectors for rapid three-dimensional imaging.

    PubMed

    Cai, Yinqiao; Tong, Xiaohua; Tong, Peng; Bu, Hongyi; Shu, Rong

    2010-12-01

    As an active remote sensor technology, the terrestrial laser scanner is widely used for direct generation of a three-dimensional (3D) image of an object in the fields of geodesy, surveying, and photogrammetry. In this article, a new laser scanner using array avalanche photodiodes, as designed by the Shanghai Institute of Technical Physics of the Chinese Academy of Sciences, is introduced for rapid collection of 3D data. The system structure of the new laser scanner is first presented, and a mathematical model is further derived to transform the original data to the 3D coordinates of the object in a user-defined coordinate system. The performance of the new laser scanner is tested through a comprehensive experiment. The result shows that the new laser scanner can scan a scene with a field view of 30° × 30° in 0.2 s and that, with respect to the point clouds obtained on the wall and ground floor surfaces, the root mean square errors for fitting the two planes are 0.21 and 0.01 cm, respectively. The primary advantages of the developed laser scanner include: (i) with a line scanning mode, the new scanner achieves simultaneously the 3D coordinates of 24 points per single laser pulse, which enables it to scan faster than traditional scanners with a point scanning mode and (ii) the new scanner makes use of two galvanometric mirrors to deflect the laser beam in both the horizontal and the vertical directions. This capability makes the instrument smaller and lighter, which is more acceptable for users.

  1. Evaluation of linear array MOSFET detectors for in vivo dosimetry to measure rectal dose in HDR brachytherapy.

    PubMed

    Haughey, Aisling; Coalter, George; Mugabe, Koki

    2011-09-01

    The study aimed to assess the suitability of linear array metal oxide semiconductor field effect transistor detectors (MOSFETs) as in vivo dosimeters to measure rectal dose in high dose rate brachytherapy treatments. The MOSFET arrays were calibrated with an Ir192 source and phantom measurements were performed to check agreement with the treatment planning system. The angular dependence, linearity and constancy of the detectors were evaluated. For in vivo measurements two sites were investigated, transperineal needle implants for prostate cancer and Fletcher suites for cervical cancer. The MOSFETs were inserted into the patients' rectum in theatre inside a modified flatus tube. The patients were then CT scanned for treatment planning. Measured rectal doses during treatment were compared with point dose measurements predicted by the TPS. The MOSFETs were found to require individual calibration factors. The calibration was found to drift by approximately 1% ±0.8 per 500 mV accumulated and varies with distance from source due to energy dependence. In vivo results for prostate patients found only 33% of measured doses agreed with the TPS within ±10%. For cervix cases 42% of measured doses agreed with the TPS within ±10%, however of those not agreeing variations of up to 70% were observed. One of the most limiting factors in this study was found to be the inability to prevent the MOSFET moving internally between the time of CT and treatment. Due to the many uncertainties associated with MOSFETs including calibration drift, angular dependence and the inability to know their exact position at the time of treatment, we consider them to be unsuitable for in vivo dosimetry in rectum for HDR brachytherapy.

  2. Generation of living cell arrays for atomic force microscopy studies.

    PubMed

    Formosa, Cécile; Pillet, Flavien; Schiavone, Marion; Duval, Raphaël E; Ressier, Laurence; Dague, Etienne

    2015-01-01

    Atomic force microscopy (AFM) is a useful tool for studying the morphology or the nanomechanical and adhesive properties of live microorganisms under physiological conditions. However, to perform AFM imaging, living cells must be immobilized firmly enough to withstand the lateral forces exerted by the scanning tip, but without denaturing them. This protocol describes how to immobilize living cells, ranging from spores of bacteria to yeast cells, into polydimethylsiloxane (PDMS) stamps, with no chemical or physical denaturation. This protocol generates arrays of living cells, allowing statistically relevant measurements to be obtained from AFM measurements, which can increase the relevance of results. The first step of the protocol is to generate a microstructured silicon master, from which many microstructured PDMS stamps can be replicated. Living cells are finally assembled into the microstructures of these PDMS stamps using a convective and capillary assembly. The complete procedure can be performed in 1 week, although the first step is done only once, and thus repeats can be completed within 1 d.

  3. A smart sensor architecture based on emergent computation in an array of outer-totalistic cells

    NASA Astrophysics Data System (ADS)

    Dogaru, Radu; Dogaru, Ioana; Glesner, Manfred

    2005-06-01

    A novel smart-sensor architecture is proposed, capable to segment and recognize characters in a monochrome image. It is capable to provide a list of ASCII codes representing the recognized characters from the monochrome visual field. It can operate as a blind's aid or for industrial applications. A bio-inspired cellular model with simple linear neurons was found the best to perform the nontrivial task of cropping isolated compact objects such as handwritten digits or characters. By attaching a simple outer-totalistic cell to each pixel sensor, emergent computation in the resulting cellular automata lattice provides a straightforward and compact solution to the otherwise computationally intensive problem of character segmentation. A simple and robust recognition algorithm is built in a compact sequential controller accessing the array of cells so that the integrated device can provide directly a list of codes of the recognized characters. Preliminary simulation tests indicate good performance and robustness to various distortions of the visual field.

  4. Development of a Microforce Sensor and Its Array Platform for Robotic Cell Microinjection Force Measurement.

    PubMed

    Xie, Yu; Zhou, Yunlei; Lin, Yuzi; Wang, Lingyun; Xi, Wenming

    2016-04-06

    Robot-assisted cell microinjection, which is precise and can enable a high throughput, is attracting interest from researchers. Conventional probe-type cell microforce sensors have some real-time injection force measurement limitations, which prevent their integration in a cell microinjection robot. In this paper, a novel supported-beam based cell micro-force sensor with a piezoelectric polyvinylidine fluoride film used as the sensing element is described, which was designed to solve the real-time force-sensing problem during a robotic microinjection manipulation, and theoretical mechanical and electrical models of the sensor function are derived. Furthermore, an array based cell-holding device with a trapezoidal microstructure is micro-fabricated, which serves to improve the force sensing speed and cell manipulation rates. Tests confirmed that the sensor showed good repeatability and a linearity of 1.82%. Finally, robot-assisted zebrafish embryo microinjection experiments were conducted. These results demonstrated the effectiveness of the sensor working with the robotic cell manipulation system. Moreover, the sensing structure, theoretical model, and fabrication method established in this study are not scale dependent. Smaller cells, e.g., mouse oocytes, could also be manipulated with this approach.

  5. Development of a Microforce Sensor and Its Array Platform for Robotic Cell Microinjection Force Measurement

    PubMed Central

    Xie, Yu; Zhou, Yunlei; Lin, Yuzi; Wang, Lingyun; Xi, Wenming

    2016-01-01

    Robot-assisted cell microinjection, which is precise and can enable a high throughput, is attracting interest from researchers. Conventional probe-type cell microforce sensors have some real-time injection force measurement limitations, which prevent their integration in a cell microinjection robot. In this paper, a novel supported-beam based cell micro-force sensor with a piezoelectric polyvinylidine fluoride film used as the sensing element is described, which was designed to solve the real-time force-sensing problem during a robotic microinjection manipulation, and theoretical mechanical and electrical models of the sensor function are derived. Furthermore, an array based cell-holding device with a trapezoidal microstructure is micro-fabricated, which serves to improve the force sensing speed and cell manipulation rates. Tests confirmed that the sensor showed good repeatability and a linearity of 1.82%. Finally, robot-assisted zebrafish embryo microinjection experiments were conducted. These results demonstrated the effectiveness of the sensor working with the robotic cell manipulation system. Moreover, the sensing structure, theoretical model, and fabrication method established in this study are not scale dependent. Smaller cells, e.g., mouse oocytes, could also be manipulated with this approach. PMID:27058545

  6. Reliability of superficial male pelvic floor structural measurements using linear-array transperineal sonography.

    PubMed

    Roll, Shawn C; Rana, Manku; Sigward, Susan M; Yani, Moheb S; Kirages, Daniel J; Kutch, Jason J

    2015-02-01

    This study evaluated reliability of measures for superficial structures of the male pelvic floor (PF) obtained via transperineal sonography. Two embalmed cadavers were dissected to identify positioning of muscles on and around the bulb of the penis and to confirm the PF protocol. Cross-sectional area (CSA) and linear thickness of the bulb of the penis, urethra, bulbospongiosus (BS) muscles, and ischiocavernosus (IC) muscles were measured on 38 transverse images from 20 male patients by three raters with varied study knowledge and sonographic experience. Intra- and inter-rater reliability were calculated with two-way, mixed effects intra-class correlation coefficients. Measures of the bulb of the penis had the best reliability. CSA of all muscles and sagittal thickness of the BS near the central tendon had good reliability. Reliability varied for rater-identified thickest muscle region and measures of the urethra. Our study suggests that structures of the male PF can be reliably evaluated using a transperineal sonographic approach.

  7. Characterization of cell seeding and specific capture of B cells in microbubble well arrays

    PubMed Central

    Jones, Meghan C.; Kobie, James J.

    2014-01-01

    Development of micro-well array systems for use in high-throughput screening of rare cells requires a detailed understanding of the factors that impact the specific capture of cells in wells and the distribution statistics of the number of cells deposited into wells. In this study we investigate the development of microbubble (MB) well array technology for sorting antigen-specific B-cells. Using Poisson statistics we delineate the important role that the fractional area of MB well opening and the cell seeding density have on determining cell seeding distribution in wells. The unique architecture of the MB well hinders captured cells from escaping the well and provides a unique microenvironmental niche that enables media changes as needed for extended cell culture. Using cell lines and primary B and T cells isolated from human peripheral blood we demonstrate the use of affinity capture agents coated in the MB wells to enrich for the selective capture of B cells. Important differences were noted in the efficacy of bovine serum albumin to block the nonspecific adsorption of primary cells relative to cell lines as well as the efficacy of the capture coatings using mixed primary B and T cells samples. These results emphasize the importance of using primary cells in technology development and suggest the need to utilize B cell capture agents that are insensitive to cell activation. PMID:23358874

  8. Linear Array Geometry Synthesis with Minimum Side Lobe Level and Null Control Using Dynamic Multi-Swarm Particle Swarm Optimizer with Local Search

    NASA Astrophysics Data System (ADS)

    Ghosh, Pradipta; Zafar, Hamim

    Linear antenna array design is one of the most important electromagnetic optimization problems of current interest. This paper describes the synthesis method of linear array geometry with minimum side lobe level and null control by the Dynamic Multi-Swarm Particle Swarm Optimizer with Local Search (DMSPSO) which optimizes the spacing between the elements of the linear array to produce a radiation pattern with minimum side lobe level and null placement control. The results of the DMSPSO algorithm have been shown to meet or beat the results obtained using other state-of-the-art metaheuristics like the Genetic Algorithm (GA),General Particle Swarm Optimization (PSO), Memetic Algorithms (MA), and Tabu Search (TS) in a statistically meaningful way. Three design examples are presented that illustrate the use of the DMSPSO algorithm, and the optimization goal in each example is easily achieved.

  9. Tunable TiO2 Nanotube Arrays for Flexible Bio-Sensitized Solar Cells

    DTIC Science & Technology

    2012-08-01

    Tunable TiO2 Nanotube Arrays for Flexible Bio-Sensitized Solar Cells by Joshua J. Martin, Mark H. Griep, Anit Giri, Samuel G. Hirsch... Tio2 Nanotube Arrays for Flexible Bio-Sensitized Solar Cells 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...pathway vs. TiO2 nanoparticles in dye-sensitized solar cell (DSSC) designs. TiNT arrays prepared by electrochemical anodization of Ti foils and

  10. Bima Array Detections of HCN in Comets Linear (C/2002 T7) and Neat (C/2001 Q4)

    NASA Technical Reports Server (NTRS)

    Friedel, D. N.; Remijan, A.; Snyder, L. E.; AHearn, M. F.; Blake, Geoffrey A.; dePater, Imke; Dickel, H. R.; Forster, J. R.; Hogerheijde, M. R.

    2004-01-01

    We present interferometric detections of HCN in comets LINEAR (C/2002 T7) and NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland Association (BIMA) Array in its D-configuration cross-correlation mode. We detected the HCN J = 1 - 0 emission line in both comets. With a 25".4 x 20".3 synthesized beam around Comet LINEAR, we found a total beam averaged HCN column density (assuming a rotation temperature of 146 K) of < N(sub T) > = 2.1(11)x 10(sup 13) cm(exp -2), and a HCN production rate of Q(HCN)=2.8(15)x 10(sup 27) s(exp -1). With a 21".3 x 17".5 synthesized beam around Comet NEAT, we found a total beam averaged HCN column density (assuming a rotation temperature of 107 K) of < N(sub T) > = 5.7(30) x 10(sup l2) cm(exp -2), and a HCN production rate of Q(HCN)=8.3(44) x 10(sup 26) s(exp -l) giving a production rate of HCN relative to H2O of approximately 0.09(5)%. The production rates relative to H2O and spatial extent of HCN are similar to previous comet observations.

  11. Flaw Shape Reconstruction from SH-Wave Array Ultrasonic Data Using Time Domain Linearized Inverse Scattering Method

    SciTech Connect

    Kimoto, K.; Hirose, S.

    2005-04-09

    A linearized inverse scattering method, so called the Kirchhoff inversion, is formulated in time domain for SH-waves measured by a contact ultrasonic transducer and tested using experimental data. The data for reconstruction are experimentally obtained by measuring ultrasonic echoes from artificial flaws in steel plate specimens. For an efficient and accurate data collection, a contact SH-wave linear array transducer is used. The shapes of the artificial flaws are reconstructed by the Kirchhoff inversion and the conventional SAFT (Synthetic Aperture Focusing Technique) using the waves from a single ray path. Comparison of the two methods shows that the Kirchhoff inversion works well for experimental data and outperforms SAFT although only an illuminated portion of the flaw boundaries is reconstructed by either method. In order to gain more information on the flaw boundaries, the Kirchhoff inversion which takes into account multiple ray paths is also tested with the same experimental data. As a result, it is shown that a larger part of the flaw boundaries can be visualized by considering the multiple ray paths.

  12. The effect of plasma on solar cell array arc characteristics

    NASA Technical Reports Server (NTRS)

    Snyder, D. B.; Tyree, E.

    1984-01-01

    The influence from the ambient plasma on the arc characteristics of a negatively biased solar cell array was investigated. The arc characteristics examined were the peak current during an arc, the decay time as the arc terminates, and the charge lost during the arc. These arc characteristics were examined in a nitrogen plasma with charge densities ranging from 15,000 to 45,000 cu cm. Background gas pressures ranged from 8x1,000,000 to 6x100,000 torr. Over these ranges of parameters no significant effect on the arc characteristics were seen. Arc characteristics were also examined for three gas species: helium, nitrogen and argon. The helium arcs have higher peak currents and shorter decay times than nitrogen and argon arcs. There are slight differences in the arc characteristics between nitrogen and argon. These differences may be caused by the differences in mass of the respective species. Also, evidence is presented for an electron emission mechanism appearing as a precursor to solar array arcs. Occassionally the plasma generator could be turned off, and currents could still be detected in the vacuum system. When these currents are presented, arcs may occur.

  13. The effect of plasma on solar cell array arc characteristics

    NASA Technical Reports Server (NTRS)

    Snyder, D. B.; Tyree, E.

    1985-01-01

    The influence from the ambient plasma on the arc characteristics of a negatively biased solar cell array was investigated. The arc characteristics examined were the peak current during an arc, the decay time as the arc terminates, and the charge lost during the arc. These arc characteristics were examined in a nitrogen plasma with charge densities ranging from 15,000 to 45,000 cu cm. Background gas pressures ranged from 8x1,000,000 to 6x100,000 torr. Over these ranges of parameters no significant effect on the arc characteristics were seen. Arc characteristics were also examined for three gas species: helium, nitrogen and argon. The helium arcs have higher peak currents and shorter decay times than nitrogen and argon arcs. There are slight differences in the arc characteristics between nitrogen and argon. These differences may be caused by the differences in mass of the respective species. Also, evidence is presented for an electron emission mechanism appearing as a precursor to solar array arcs. Occasionally the plasma generator could be turned off, and currents could still be detected in the vacuum system. When these currents are presented, arcs may occur.

  14. Light absorption and emission in nanowire array solar cells.

    PubMed

    Kupec, Jan; Stoop, Ralph L; Witzigmann, Bernd

    2010-12-20

    Inorganic nanowires are under intense research for large scale solar power generation intended to ultimately contribute a substantial fraction to the overall power mix. Their unique feature is to allow different pathways for the light absorption and carrier transport. In this publication we investigate the properties of a nanowire array acting as a photonic device governed by wave-optical phenomena. We solve the Maxwell equations and calculate the light absorption efficiency for the AM1.5d spectrum and give recommendations on the design. Due to concentration of the incident sunlight at a microscopic level the absorptivity of nanowire solar cells can exceed the absorptivity of an equal amount of material used in thin-film devices. We compute the local density of photon states to assess the effect of emission enhancement, which influences the radiative lifetime of excess carriers. This allows us to compute the efficiency limit within the framework of detailed balance. The efficiency is highly sensitive with respect to the diameter and distance of the nanowires. Designs featuring nanowires below a certain diameter will intrinsically feature low short-circuit current that cannot be compensated even by increasing the nanowire density. Optimum efficiency is not achieved in densely packed arrays, in fact spacing the nanowires further apart (simultaneously decreasing the material use) can even improve efficiency in certain scenarios. We observe absorption enhancement reducing the material use. In terms of carrier generation per material use, nanowire devices can outperform thin-film devices by far.

  15. TAB interconnects for space concentrator solar cell arrays

    NASA Technical Reports Server (NTRS)

    Avery, J.; Bauman, J. S.; Gallagher, P.; Yerkes, J. W.

    1993-01-01

    The Boeing Company has evaluated the use of Tape Automated Bonding (TAB) and Surface Mount Technology (SMT) for a highly reliable, low cost interconnect for concentrator solar cell arrays. TAB and SMT are currently used in the electronics industry for chip interconnects and printed circuit board assembly. TAB tape consists of sixty-four 3-mil/1-oz tin-plated copper leads on 8-mil centers. The leads are thermocompression gang bonded to GaAs concentrator solar cell with silver contacts. This bond, known as an Inner Lead Bond (ILB), allows for pretesting and sorting capability via nondestruct wire bond pull and flash testing. Destructive wire pull tests resulted in preferred mid-span failures. Improvements in fill factor were attributed to decreased contact resistance on TAB bonded cells. Preliminary thermal cycling and aging tests were shown excellent bond strength and metallurgical results. Auger scans of bond sites reveals an Ag-Cu-Tin composition. Improper bonds are identified through flash testing as a performance degradation. On going testing of cells are underway at Lewis Research Center. SMT techniques are utilized to excise and form TAB leads post ILB. The formed leads' shape isolates thermal mismatches between the cells and the flex circuit they are mounted on. TABed cells are picked and placed with a gantry x-y-z positioning system with pattern recognition. Adhesives are selected to avoid thermal expansion mismatch and promote thermal transfer to the flex circuit. TAB outer lead bonds are parallel gap welded (PGW) to the flex circuit to finish the concentrator solar cell subassembly.

  16. A microfluidic cell culture array with various oxygen tensions.

    PubMed

    Peng, Chien-Chung; Liao, Wei-Hao; Chen, Ying-Hua; Wu, Chueh-Yu; Tung, Yi-Chung

    2013-08-21

    Oxygen tension plays an important role in regulating various cellular functions in both normal physiology and disease states. Therefore, drug testing using conventional in vitro cell models under normoxia often possesses limited prediction capability. A traditional method of setting an oxygen tension in a liquid medium is by saturating it with a gas mixture at the desired level of oxygen, which requires bulky gas cylinders, sophisticated control, and tedious interconnections. Moreover, only a single oxygen tension can be tested at the same time. In this paper, we develop a microfluidic cell culture array platform capable of performing cell culture and drug testing under various oxygen tensions simultaneously. The device is fabricated using an elastomeric material, polydimethylsiloxane (PDMS) and the well-developed multi-layer soft lithography (MSL) technique. The prototype device has 4 × 4 wells, arranged in the same dimensions as a conventional 96-well plate, for cell culture. The oxygen tensions are controlled by spatially confined oxygen scavenging chemical reactions underneath the wells using microfluidics. The platform takes advantage of microfluidic phenomena while exhibiting the combinatorial diversities achieved by microarrays. Importantly, the platform is compatible with existing cell incubators and high-throughput instruments (liquid handling systems and plate readers) for cost-effective setup and straightforward operation. Utilizing the developed platform, we successfully perform drug testing using an anti-cancer drug, triapazamine (TPZ), on adenocarcinomic human alveolar basal epithelial cell line (A549) under three oxygen tensions ranging from 1.4% to normoxia. The developed platform is promising to provide a more meaningful in vitro cell model for various biomedical applications while maintaining desired high throughput capabilities.

  17. TAB interconnects for space concentrator solar cell arrays

    NASA Astrophysics Data System (ADS)

    Avery, J.; Bauman, J. S.; Gallagher, P.; Yerkes, J. W.

    1993-05-01

    The Boeing Company has evaluated the use of Tape Automated Bonding (TAB) and Surface Mount Technology (SMT) for a highly reliable, low cost interconnect for concentrator solar cell arrays. TAB and SMT are currently used in the electronics industry for chip interconnects and printed circuit board assembly. TAB tape consists of sixty-four 3-mil/1-oz tin-plated copper leads on 8-mil centers. The leads are thermocompression gang bonded to GaAs concentrator solar cell with silver contacts. This bond, known as an Inner Lead Bond (ILB), allows for pretesting and sorting capability via nondestruct wire bond pull and flash testing. Destructive wire pull tests resulted in preferred mid-span failures. Improvements in fill factor were attributed to decreased contact resistance on TAB bonded cells. Preliminary thermal cycling and aging tests were shown excellent bond strength and metallurgical results. Auger scans of bond sites reveals an Ag-Cu-Tin composition. Improper bonds are identified through flash testing as a performance degradation. On going testing of cells are underway at Lewis Research Center. SMT techniques are utilized to excise and form TAB leads post ILB. The formed leads' shape isolates thermal mismatches between the cells and the flex circuit they are mounted on. TABed cells are picked and placed with a gantry x-y-z positioning system with pattern recognition. Adhesives are selected to avoid thermal expansion mismatch and promote thermal transfer to the flex circuit. TAB outer lead bonds are parallel gap welded (PGW) to the flex circuit to finish the concentrator solar cell subassembly.

  18. Deformation measurement of individual cells in large populations using a single-cell microchamber array chip.

    PubMed

    Doh, I; Lee, W C; Cho, Y-H; Pisano, A P; Kuypers, F A

    2012-04-23

    We analyze the deformability of individual red blood cells (RBCs) using SiCMA technology. Our approach is adequate to quickly measure large numbers of individual cells in heterogeneous populations. Individual cells are trapped in a large-scale array of micro-wells, and dielectrophoretic (DEP) force is applied to deform the cells. The simple structures of micro-wells and DEP electrodes facilitate the analysis of thousands of RBCs in parallel. This unique method allows the correlation of red cell deformation with cell surface and cytosolic characteristics to define the distribution of individual cellular characteristics in heterogeneous populations.

  19. Cell manipulation tool with combined microwell array and optical tweezers for cell isolation and deposition

    NASA Astrophysics Data System (ADS)

    Wang, Xiaolin; Gou, Xue; Chen, Shuxun; Yan, Xiao; Sun, Dong

    2013-07-01

    Isolation from rare cells and deposition of sorted cells with high accuracy for further study are critical to a wide range of biomedical applications. In the current paper, we report an automated cell manipulation tool with combined optical tweezers and a uniquely designed microwell array, which functions for recognition, isolation, assembly, transportation and deposition of the interesting cells. The microwell array allows the passive hydrodynamic docking of cells, while offering the opportunity to inspect the interesting cell phenotypes with high spatio-temporal resolution based on the flexible image processing technique. In addition, dynamic and parallel cell manipulation in three dimensions can realize the target cell levitation from microwell and pattern assembly with multiple optical traps. Integrated with the programmed motorized stage, the optically levitated and assembled cells can be transported and deposited to the predefined microenvironment, so the tool can facilitate the integration of other on-chip functionalities for further study without removing these isolated cells from the chip. Experiments on human embryonic stem cells and yeast cells are performed to demonstrate the effectiveness of the proposed cell manipulation tool. Besides the application to cell isolation and deposition, three other biological applications with this tool are also presented.

  20. III-nitride core–shell nanowire arrayed solar cells.

    PubMed

    Wierer, Jonathan J; Li, Qiming; Koleske, Daniel D; Lee, Stephen R; Wang, George T

    2012-05-17

    A solar cell based on a hybrid nanowire–film architecture consisting of a vertically aligned array of InGaN/GaN multi-quantum well core–shell nanowires which are electrically connected by a coalesced p-InGaN canopy layer is demonstrated. This unique hybrid structure allows for standard planar device processing, solving a key challenge with nanowire device integration, while enabling various advantages by the nanowire absorbing region such as higher indium composition InGaN layers by elastic strain relief, more efficient carrier collection in thinner layers, and enhanced light trapping from nano-scale optical index changes. This hybrid structure is fabricated into working solar cells exhibiting photoresponse out to 2.1 eV and short-circuit current densities of ~1 mA cm(-2) under 1 sun AM1.5G. This proof-of-concept nanowire-based device demonstrates a route forward for high-efficiency III-nitride solar cells.

  1. Single cell trapping and DNA damage analysis using microwell arrays

    PubMed Central

    Wood, David K.; Weingeist, David M.; Bhatia, Sangeeta N.; Engelward, Bevin P.

    2010-01-01

    With a direct link to cancer, aging, and heritable diseases as well as a critical role in cancer treatment, the importance of DNA damage is well-established. The intense interest in DNA damage in applications ranging from epidemiology to drug development drives an urgent need for robust, high throughput, and inexpensive tools for objective, quantitative DNA damage analysis. We have developed a simple method for high throughput DNA damage measurements that provides information on multiple lesions and pathways. Our method utilizes single cells captured by gravity into a microwell array with DNA damage revealed morphologically by gel electrophoresis. Spatial encoding enables simultaneous assays of multiple experimental conditions performed in parallel with fully automated analysis. This method also enables novel functionalities, including multiplexed labeling for parallel single cell assays, as well as DNA damage measurement in cell aggregates. We have also developed 24- and 96-well versions, which are applicable to high throughput screening. Using this platform, we have quantified DNA repair capacities of individuals with different genetic backgrounds, and compared the efficacy of potential cancer chemotherapeutics as inhibitors of a critical DNA repair enzyme, human AP endonuclease. This platform enables high throughput assessment of multiple DNA repair pathways and subpathways in parallel, thus enabling new strategies for drug discovery, genotoxicity testing, and environmental health. PMID:20534572

  2. Design of a 5-MA 100-ns linear-transformer-driver accelerator for wire array Z-pinch experiments

    NASA Astrophysics Data System (ADS)

    Zhou, Lin; Li, Zhenghong; Wang, Zhen; Liang, Chuan; Li, Mingjia; Qi, Jianmin; Chu, Yanyun

    2016-03-01

    The linear-transformer-driver (LTD) is a recently developed pulsed-power technology that shows great promise for a number of applications. These include a Z -pinch-driven fission-fusion-hybrid reactor that is being developed by the Chinese Academy of Engineering Physics. In support of the reactor development effort, we are planning to build an LTD-based accelerator that is optimized for driving wire-array Z -pinch loads. The accelerator comprises six modules in parallel, each of which has eight series 0.8-MA LTD cavities in a voltage-adder configuration. Vacuum transmission lines are used from the interior of the adder to the central vacuum chamber where the load is placed. Thus the traditional stack-flashover problem is eliminated. The machine is 3.2 m tall and 12 m in outer diameter including supports. A prototype cavity was built and tested for more than 6000 shots intermittently at a repetition rate of 0.1 Hz. A novel trigger, in which only one input trigger pulse is needed by utilizing an internal trigger brick, was developed and successfully verified in these shots. A full circuit modeling was conducted for the accelerator. The simulation result shows that a current pulse rising to 5.2 MA in 91 ns (10%-90%) can be delivered to the wire-array load, which is 1.5 cm in height, 1.2 cm in initial radius, and 1 mg in mass. The maximum implosion velocity of the load is 32 cm /μ s when compressed to 0.1 of the initial radius. The maximum kinetic energy is 78 kJ, which is 11.7% of the electric energy stored in the capacitors. This accelerator is supposed to enable a radiation energy efficiency of 20%-30%, providing a high efficient facility for research on the fast Z pinch and technologies for repetition-rate-operated accelerators.

  3. Internal structure of the San Jacinto fault zone at Blackburn Saddle from seismic data of a linear array

    NASA Astrophysics Data System (ADS)

    Share, Pieter-Ewald; Ben-Zion, Yehuda; Ross, Zachary E.; Qiu, Hongrui; Vernon, Frank L.

    2017-08-01

    Local and teleseismic earthquake waveforms recorded by a 180-m-long linear array (BB) with seven seismometers crossing the Clark fault of the San Jacinto fault zone northwest of Anza are used to image a deep bimaterial interface and core damage structure of the fault. Delay times of P waves across the array indicate an increase in slowness from the southwest most (BB01) to the northeast most (BB07) station. Automatic algorithms combined with visual inspection and additional analyses are used to identify local events generating fault zone head and trapped waves. The observed fault zone head waves imply that the Clark fault in the area is a sharp bimaterial interface, with lower seismic velocity on the southwest side. The moveout between the head and direct P arrivals for events within ∼40 km epicentral distance indicates an average velocity contrast across the fault over that section and the top 20 km of 3.2 per cent. A constant moveout for events beyond ∼40 km to the southeast is due to off-fault locations of these events or because the imaged deep bimaterial interface is discontinuous or ends at that distance. The lack of head waves from events beyond ∼20 km to the northwest is associated with structural complexity near the Hemet stepover. Events located in a broad region generate fault zone trapped waves at stations BB04-BB07. Waveform inversions indicate that the most likely parameters of the trapping structure are width of ∼200 m, S velocity reduction of 30-40 per cent with respect to the bounding blocks, Q value of 10-20 and depth of ∼3.5 km. The trapping structure and zone with largest slowness are on the northeast side of the fault. The observed sense of velocity contrast and asymmetric damage across the fault suggest preferred rupture direction of earthquakes to the northwest. This inference is consistent with results of other geological and seismological studies.

  4. Linearity and effective optical pathlength of liquid waveguide capillary cells

    NASA Astrophysics Data System (ADS)

    Belz, Mathias; Dress, Peter; Sukhitskiy, Aleksandr; Liu, Suyi

    1999-11-01

    The validity of using Beer's Law to describe liquid waveguide capillary cells (LWCC) as absorption cells with increased optical pathlength was investigated. Experimental and theoretical results for two types of LWCC are presented. 'Type I' LWCCs are constructed with solid TEFLON AF tubing. 'Type II' LWCCs consist of quartz tubing with an outer coating of TEFLON AF. UV/Vis absorbance spectra versus chromophore concentration were found to be linear for both LWCC types within the wavelength range and absorbance accuracy of the spectrophotometer used. The ratio between 'effective' and 'physical' pathlength, EPLR was determined experimentally for both LWCC types. Type I cells had an effective optical pathlength that was statistically indistinguishable from the physical pathlength on a 95 percent probability basis. Type II cells had an effective optical pathlength that was slightly shorter than the physical pathlength, dependent on the cell's inner diameter and wall thickness. A theoretical model explaining Type I LWCC result is presented. Our results indicate that Beer- Lambert's Law can be applied to both types of LWCCs for UV/Vis absorption spectroscopy.

  5. Performance of the Linear Gas Cell at the NSCL

    NASA Astrophysics Data System (ADS)

    Cooper, Kortney; Morrissey, David; Ringle, Ryan; Schwarz, Stefan; Sumithrarachchi, Chandana; Savard, Guy

    2014-09-01

    Beam thermalization allows projectile fragmentation facilities to produce low-energy ion beams. The beam thermalization technique employed by the National Superconducting Cyclotron Laboratory (NSCL) involves high-energy ion beams first passing through solid degraders to remove the bulk of the beam's kinetic energy. The remaining kinetic energy is then dissipated through collisions with the buffer gas atoms of a linear gas cell constructed by Argonne National Lab (ANL). Numerous experiments have been performed for the commissioning and online operation of the gas cell. These experiments used incident ions that ranged from 29Mg, 29P, 33Cl, 37K, 40S, 46Ar, to 76Ga at incoming rates ranging from 102 pps to 107 pps. The extraction efficiency as well as the overall efficiency of the system has been analyzed for each experiment. LISE + + , particle-in-cell (PIC), and SIMION simulations have been carried out for the data obtained with 76Ga ions. Both the experimental and simulated results for the gas cell's performance will be presented and discussed. Beam thermalization allows projectile fragmentation facilities to produce low-energy ion beams. The beam thermalization technique employed by the National Superconducting Cyclotron Laboratory (NSCL) involves high-energy ion beams first passing through solid degraders to remove the bulk of the beam's kinetic energy. The remaining kinetic energy is then dissipated through collisions with the buffer gas atoms of a linear gas cell constructed by Argonne National Lab (ANL). Numerous experiments have been performed for the commissioning and online operation of the gas cell. These experiments used incident ions that ranged from 29Mg, 29P, 33Cl, 37K, 40S, 46Ar, to 76Ga at incoming rates ranging from 102 pps to 107 pps. The extraction efficiency as well as the overall efficiency of the system has been analyzed for each experiment. LISE + + , particle-in-cell (PIC), and SIMION simulations have been carried out for the data obtained

  6. Cost competitiveness of a solar cell array power source for ATS-6 educational TV terminal

    NASA Technical Reports Server (NTRS)

    Masters, R. M.

    1975-01-01

    A cost comparison is made between a terrestrial solar cell array power system and a variety of other power sources for the ATS-6 Satellite Instructional Television Experiment (SITE) TV terminals in India. The solar array system was sized for a typical Indian location, Lahore. Based on present capital and fuel costs, the solar cell array power system is a close competitor to the least expensive alternate power system. A feasibility demonstration of a terrestrial solar cell array system powering an ATS-6 receiver terminal at Cleveland, Ohio is described.

  7. Accurate quantification of atherosclerotic plaque volume by 3D vascular ultrasound using the volumetric linear array method.

    PubMed

    López-Melgar, Beatriz; Fernández-Friera, Leticia; Sánchez-González, Javier; Vilchez, Jean Paul; Cecconi, Alberto; Mateo, Jesús; Peñalvo, José L; Oliva, Belén; García-Ruiz, Jose M; Kauffman, Steve; Jiménez-Borreguero, Luis Jesús; Ruiz-Cabello, Jesús; Fernández-Ortiz, Antonio; Ibáñez, Borja; Fuster, Valentín

    2016-05-01

    Direct quantification of atherosclerotic plaque volume by three-dimensional vascular ultrasound (3DVUS) is more reproducible than 2DUS-based three-dimensional (2D/3D) techniques that generate pseudo-3D volumes from summed 2D plaque areas; however, its accuracy has not been reported. We aimed to determine 3DVUS accuracy for plaque volume measurement with special emphasis on small plaques (a hallmark of early atherosclerosis). The in vitro study consisted of nine phantoms of different volumes (small and medium-large) embedded at variable distances from the surface (superficial vs. >5 cm-depth) and comparison of 3DVUS data generated using a novel volumetric-linear array method with the real phantom volumes. The in vivo study was undertaken in a rabbit model of atherosclerosis in which 3DVUS and 2D/3D volume measurements were correlated against gold-standard histological measurements. In the in vitro setting, there was a strong correlation between 3DVUS measures and real phantom volume both for small (3.0-64.5 mm(3) size) and medium-large (91.1-965.5 mm(3) size) phantoms embedded superficially, with intraclass correlation coefficients (ICC) of 0.99 and 0.98, respectively; conversely, when phantoms were placed at >5 cm, the correlation was only moderate (ICC = 0.67). In the in vivo setting there was strong correlation between 3DVUS-measured plaque volumes and the histological gold-standard (ICC = 0.99 [4.02-92.5 mm(3) size]). Conversely, the correlation between 2D/3D values and the histological gold standard (sum of plaque areas) was weaker (ICC = 0.87 [49-520 mm(2) size]), with large dispersion of the differences between measurements in Bland-Altman plots (mean error, 79.2 mm(2)). 3DVUS using the volumetric-linear array method accurately measures plaque volumes, including those of small plaques. Measurements are more accurate for superficial arterial territories than for deep territories. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. Design to improve photoelectric efficiency for photovoltaic cell array for laser power beaming

    NASA Astrophysics Data System (ADS)

    Li, Xiaojiang; Li, Beibei

    2017-02-01

    Photovoltaic cell (PV) array is a photovoltaic conversion device for laser power beaming, and uneven distribution of laser beam energy will have negative influence on the photovoltaic efficiency of PV array. In order to improve the photovoltaic efficiency under uneven laser irradiation, an optimized and efficient parallel-series PV array is designed. Based on the mathematical model and MATLB/Simulink simulation model of PV array , the influencing factors of photovoltaic efficiency are analyzed, and the concept and scheme to improve the photovoltaic efficiency of parallel-series PV array are proposed. Finally, compared with typical PV array, the effects improving efficiency of optimized array is simulated and analyzed. The simulation results show that under uneven laser irradiation, the optimized parallel-series PV array can obtain higher photovoltaic efficiency.

  9. Evaluation of solar cells and arrays for potential solar power satellite applications

    NASA Technical Reports Server (NTRS)

    Almgren, D. W.; Csigi, K.; Gaudet, A. D.

    1978-01-01

    Proposed solar array designs and manufacturing methods are evaluated to identify options which show the greatest promise of leading up to the develpment of a cost-effective SPS solar cell array design. The key program elements which have to be accomplished as part of an SPS solar cell array development program are defined. The issues focussed on are: (1) definition of one or more designs of a candidate SPS solar array module, using results from current system studies; (2) development of the necessary manufacturing requirements for the candidate SPS solar cell arrays and an assessment of the market size, timing, and industry infrastructure needed to produce the arrays for the SPS program; (3) evaluation of current DOE, NASA and DOD photovoltaic programs to determine the impacts of recent advances in solar cell materials, array designs and manufacturing technology on the candidate SPS solar cell arrays; and (4) definition of key program elements for the development of the most promising solar cell arrays for the SPS program.

  10. EMG-torque Relation in Chronic Stroke: A Novel EMG Complexity Representation with A Linear Electrode Array.

    PubMed

    Zhang, Xu; Wang, Dongqing; Yu, Zaiyang; Chen, Xiang; Li, Sheng; Zhou, Ping

    2016-11-08

    This study examines the electromyogram (EMG) - torque relation for chronic stroke survivors using a novel EMG complexity representation. Ten stroke subjects performed a series of submaximal isometric elbow flexion tasks using their affected and contralateral arms, respectively, while a 20-channel linear electrode array was used to record surface EMG from the biceps brachii muscles. The sample entropy (SampEn) of surface EMG signals was calculated with both global and local tolerance schemes. A regression analysis was performed between SampEn of each channel's surface EMG and elbow flexion torque. It was found that a linear regression can be used to well describe the relation between surface EMG SampEn and the torque. Each channel's root mean square (RMS) amplitude of surface EMG signal in the different torque level was computed to determine the channel with the highest EMG amplitude. The slope of the regression (observed from the channel with the highest EMG amplitude) was smaller on the impaired side than on the non-impaired side in 8 of the 10 subjects, regardless of the tolerance scheme (global or local) and the range of torques (full or matched range) used for comparison. The surface EMG signals from the channels above the estimated muscle innervation zones demonstrated significantly lower levels of complexity compared with other channels between innervation zones and muscle tendons. The study provides a novel point of view of the EMG-torque relation in the complexity domain, and reveals its alterations post stroke, which are associated with complex neural and muscular changes post stroke. The slope difference between channels with regard to innervation zones also confirms the relevance of electrode position in surface EMG analysis.

  11. Technical evaluation of Solar Cells, Inc., CdTe module and array at NREL

    SciTech Connect

    Kroposki, B.; Strand, T.; Hansen, R.; Powell, R.; Sasala, R.

    1996-05-01

    The Engineering and Technology Validation Team at the National Renewable Energy Laboratory (NREL) conducts in-situ technical evaluations of polycrystalline thin-film photovoltaic (PV) modules and arrays. This paper focuses on the technical evaluation of Solar Cells, Inc., (SCI) cadmium telluride (CdTe) module and array performance by attempting to correlate individual module and array performance. This is done by examining the performance and stability of the modules and array over a period of more than one year. Temperature coefficients for module and array parameters (P{sub max}, V{sub oc}, V{sub max}, I{sub sc}, I{sub max}) are also calculated.

  12. Cancer Cell Analyses at the Single Cell-Level Using Electroactive Microwell Array Device

    PubMed Central

    Kobayashi, Marina; Kim, Soo Hyeon; Nakamura, Hiroko; Kaneda, Shohei; Fujii, Teruo

    2015-01-01

    Circulating tumor cells (CTCs), shed from primary tumors and disseminated into peripheral blood, are playing a major role in metastasis. Even after isolation of CTCs from blood, the target cells are mixed with a population of other cell types. Here, we propose a new method for analyses of cell mixture at the single-cell level using a microfluidic device that contains arrayed electroactive microwells. Dielectrophoretic (DEP) force, induced by the electrodes patterned on the bottom surface of the microwells, allows efficient trapping and stable positioning of single cells for high-throughput biochemical analyses. We demonstrated that various on-chip analyses including immunostaining, viability/apoptosis assay and fluorescent in situ hybridization (FISH) at the single-cell level could be conducted just by applying specific reagents for each assay. Our simple method should greatly help discrimination and analysis of rare cancer cells among a population of blood cells. PMID:26558904

  13. Reflection at a liquid-solid interface of a transient ultrasonic field radiated by a linear phased array transducer.

    PubMed

    Maghlaoui, Nadir; Belgroune, Djema; Ourak, Mohamed; Djelouah, Hakim

    2016-09-01

    In order to put in evidence the specular reflection and the non-specular reflection in the transient case, we have used a model for the study of the transient ultrasonic waves radiated by a linear phased array transducer in a liquid and reflected by a solid plane interface. This method is an extension of the angular spectrum method to the transient case where the reflection at the plane interface is taken into account by using the reflection coefficient for harmonic plane waves. The results obtained highlighted the different components of the ultrasonic field: the direct and edge waves as well as the longitudinal head waves or leaky Rayleigh waves. The transient representation of these waves have been carefully analyzed and discussed by the rays model. Instantaneous cartographies allowed a clear description of all the waves which appear at the liquid-solid interface. The obtained results have been compared to those obtained with a finite element method package. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. An Intelligent Sensor Array Distributed System for Vibration Analysis and Acoustic Noise Characterization of a Linear Switched Reluctance Actuator

    PubMed Central

    Salvado, José; Espírito-Santo, António; Calado, Maria

    2012-01-01

    This paper proposes a distributed system for analysis and monitoring (DSAM) of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs). The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications. PMID:22969364

  15. An intelligent sensor array distributed system for vibration analysis and acoustic noise characterization of a linear switched reluctance actuator.

    PubMed

    Salvado, José; Espírito-Santo, António; Calado, Maria

    2012-01-01

    This paper proposes a distributed system for analysis and monitoring (DSAM) of vibrations and acoustic noise, which consists of an array of intelligent modules, sensor modules, communication bus and a host PC acting as data center. The main advantages of the DSAM are its modularity, scalability, and flexibility for use of different type of sensors/transducers, with analog or digital outputs, and for signals of different nature. Its final cost is also significantly lower than other available commercial solutions. The system is reconfigurable, can operate either with synchronous or asynchronous modes, with programmable sampling frequencies, 8-bit or 12-bit resolution and a memory buffer of 15 kbyte. It allows real-time data-acquisition for signals of different nature, in applications that require a large number of sensors, thus it is suited for monitoring of vibrations in Linear Switched Reluctance Actuators (LSRAs). The acquired data allows the full characterization of the LSRA in terms of its response to vibrations of structural origins, and the vibrations and acoustic noise emitted under normal operation. The DSAM can also be used for electrical machine condition monitoring, machine fault diagnosis, structural characterization and monitoring, among other applications.

  16. 1D layered velocity models and microseismic event locations: synthetic examples for a case with a single linear receiver array

    NASA Astrophysics Data System (ADS)

    Akram, Jubran; Eaton, David W.

    2017-10-01

    We discuss various aspects of 1D velocity-model building for application to microseismic data analysis. We generate simple synthetic example data using a widely used single linear array geometry. The synthetic data contain 30 sources with known locations for a reference model based on previous studies of the Barnett shale. We investigate several key factors that should be considered, including selection of the calibration technique, inclusion of a priori information such as lateral heterogeneity and parameter ranges, and choice of algorithm for travel time computations. For the source-receiver geometry considered here, hypocenter location errors (±6 m in X and ±12 m in Z) can result from differently calibrated models only and without including the errors in picked arrival times and polarization estimates. We find that the errors in hypocenter locations are reduced (±3 m in X and ±6 m in Z) when a model calibrated with multiple shots simultaneously is used. Using four different models (vertical fault, dipping layers, channels, and these effects combined), we demonstrate that systematic errors in hypocenter locations can result when a 1D layered model is used in lieu of a laterally heterogeneous subsurface. Finally, we show that event locations from a velocity model calibrated using direct-arrival times are more stable than from a model calibrated with first-arrival times.

  17. Real-time photoacoustic and ultrasound imaging: a simple solution for clinical ultrasound systems with linear arrays.

    PubMed

    Montilla, Leonardo G; Olafsson, Ragnar; Bauer, Daniel R; Witte, Russell S

    2013-01-07

    Recent clinical studies have demonstrated that photoacoustic imaging (PAI) provides important diagnostic information during a routine breast exam for cancer. PAI enhances contrast between blood vessels and background tissue, which can help characterize suspicious lesions. However, most PAI systems are either not compatible with commercial ultrasound systems or inefficiently deliver light to the region of interest, effectively reducing the sensitivity of the technique. To address and potentially overcome these limitations, we developed an accessory for a standard linear ultrasound array that optimizes light delivery for PAI. The photoacoustic enabling device (PED) exploits an optically transparent acoustic reflector to help direct laser illumination to the region of interest. This study compares the PED with standard fiber bundle illumination in scattering and non-scattering media. In scattering media with the same incident fluence, the PED enhanced the photoacoustic signal by 18 dB at a depth of 5 mm and 6 dB at a depth of 20 mm. To demonstrate in vivo feasibility, we also used the device to image a mouse with a pancreatic tumor. The PED identified blood vessels at the periphery of the tumor, suggesting that PAI provides complementary contrast to standard pulse echo ultrasound. The PED is a simple and inexpensive solution that facilitates the translation of PAI technology to the clinic for routine screening of breast cancer.

  18. Limited-view photoacoustic imaging based on linear-array detection and filtered mean-backprojection-iterative reconstruction

    NASA Astrophysics Data System (ADS)

    Ma, Songbo; Yang, Sihua; Guo, Hua

    2009-12-01

    Most existing photoacoustic tomography techniques require collecting complete projection data that are acquired on a defined circle surrounding the object. However, in clinical application, the object can only be approached from a limited angle mostly. Furthermore, with the incomplete projection data acquired in limited view, the general filtered backprojection algorithm will streak image artifacts nearby the reconstructed location of absorbers. In this paper, we present a limited-view-scanning photoacoustic imaging system with a linear transducer array and develop a filtered mean-backprojection-iteration (FMBPI) algorithm to reconstruct the absorbed optical deposit distribution. The FMBPI algorithm combines the terseness of the filtered backprojection algorithm with the accuracy of the iterative reconstruction algorithm. Numerical simulation and experimental results validate that the algorithm can effectively reconstruct high-quality image with limited-view data. It is also demonstrated that with the FMBPI algorithm, the limited-view-scanning multielement photoacoustic imaging system has a great potential to be applied in fast noninvasive clinic diagnosis of breast cancer at the early stage.

  19. Crosstalk Reduction for High-Frequency Linear-Array Ultrasound Transducers Using 1–3 Piezocomposites With Pseudo-Random Pillars

    PubMed Central

    Yang, Hao-Chung; Cannata, Jonathan; Williams, Jay; Shung, K. Kirk

    2013-01-01

    The goal of this research was to develop a novel diced 1–3 piezocomposite geometry to reduce pulse–echo ring down and acoustic crosstalk between high-frequency ultrasonic array elements. Two PZT-5H-based 1–3 composites (10 and 15 MHz) of different pillar geometries [square (SQ), 45° triangle (TR), and pseudo-random (PR)] were fabricated and then made into single-element ultrasound transducers. The measured pulse–echo waveforms and their envelopes indicate that the PR composites had the shortest −20-dB pulse length and highest sensitivity among the composites evaluated. Using these composites, 15-MHz array subapertures with a 0.95λ pitch were fabricated to assess the acoustic crosstalk between array elements. The combined electrical and acoustical crosstalk between the nearest array elements of the PR array sub-apertures (−31.8 dB at 15 MHz) was 6.5 and 2.2 dB lower than those of the SQ and the TR array subapertures, respectively. These results demonstrate that the 1–3 piezocomposite with the pseudo-random pillars may be a better choice for fabricating enhanced high-frequency linear-array ultrasound transducers; especially when mechanical dicing is used. PMID:23143580

  20. Deep linear ultrasonic sensor array observation for particle migration related with tectonic movements; A proposal for tsunami early warning

    NASA Astrophysics Data System (ADS)

    Acar, Dursun; Alpar, Bedri; Taymaz, Tuncay; Yolsal Çevikbilen, Seda; Özeren, Sinan; Eken, Tuna; Çaǧatay, Namık; Elbek, Şebnem; Sarı, Erol; Eriş, K. Kadir

    2017-04-01

    Recent tsunami warning systems has equipped with vertically placed point-transducers for measuring surface level of water. However, they are capable for secondary or more after current stages of changing water mass directions by driven tectonic forces. Secondly, they are efficient on continent shelves about increasing wave-amplitude and stuck mass of water. Atmospheric pressure and wind velocity measurements provide auxiliary correction for eliminate wrong alerts. Deep ocean bed and sediment-water interface area is one of the best observational zone about primary water currents due to fault movements. Reverse or normal fault mechanism earthquakes may give only a short time for tsunami escape even with the help of coastal tsunami alert centres. However, we can save more time with observation of suspended or semi-placed particles at the oceanic-bed with parallel-array sensors, which are more efficient than a single transducer during an earthquake or any slow deformation stage of basin. Because one or more far transducers cannot be able to get information about particle dimensions and density clouds, for example, how fast they are at low velocities (e.g. in the order of 1 mm per second) during acceleration of water masses under tectonic forces. At faster velocities, linear-array transducer series are more efficient since they are even sensitive to their neighbour-sensor scanning areas. Because triangular scanning area of an individual sensor expands to its neighbour areas and it receives sound-beam reflections coming back from the same particle. Homogenously separated piezo-crystal structure provides a hammer effect with less trigger-energy under high-pressure. The experiences about high velocity (up to 1 m per second) and very-close particle observations were successful at a close-water circuit prepared by using 5 cm diameter pipe-pomp system. Observation supports earthquake early warning variety work about concentration of radon gas, free ions, magnetic field and

  1. Progressive Transverse Microtubule Array Organization in Hormone-Induced Arabidopsis Hypocotyl Cells[W

    PubMed Central

    Vineyard, Laura; Elliott, Andrew; Dhingra, Sonia; Lucas, Jessica R.; Shaw, Sidney L.

    2013-01-01

    The acentriolar cortical microtubule arrays in dark-grown hypocotyl cells organize into a transverse coaligned pattern that is critical for axial plant growth. In light-grown Arabidopsis thaliana seedlings, the cortical array on the outer (periclinal) cell face creates a variety of array patterns with a significant bias (>3:1) for microtubules polymerizing edge-ward and into the side (anticlinal) faces of the cell. To study the mechanisms required for creating the transverse coalignment, we developed a dual-hormone protocol that synchronously induces ∼80% of the light-grown hypocotyl cells to form transverse arrays over a 2-h period. Repatterning occurred in two phases, beginning with an initial 30 to 40% decrease in polymerizing plus ends prior to visible changes in the array pattern. Transverse organization initiated at the cell’s midzone by 45 min after induction and progressed bidirectionally toward the apical and basal ends of the cell. Reorganization corrected the edge-ward bias in polymerization and proceeded without transiting through an obligate intermediate pattern. Quantitative comparisons of uninduced and induced microtubule arrays showed a limited deconstruction of the initial periclinal array followed by a progressive array reorganization to transverse coordinated between the anticlinal and periclinal cell faces. PMID:23444330

  2. Transcription factor network reconstruction using the living cell array.

    PubMed

    Yang, Eric; Yarmush, Martin L; Androulakis, Ioannis P

    2009-02-07

    The objective of identifying transcriptional regulatory networks is to provide insights as to what governs an organism's long term response to external stimuli. We explore the coupling of the living cell array (LCA), a novel microfluidics device which utilizes fluorescence levels as a surrogate for transcription factor activity with reverse Euler deconvolution (RED) a computational technique proposed in this work to decipher the dynamics of the interactions. It is hypothesized that these two methods will allow us to first assess the underlying network architecture associated with the transcription factor network as well as specific mechanistic consequences of transcription factor activation such as receptor dimerization or tolerance. The overall approach identifies evidence of time-lagged response which may be indicative of mechanisms such as receptor dimerization, tolerance mechanisms which are evidence of various receptor mediated dynamics, and feedback loops which regulate the response of an organism to changing environmental conditions. Furthermore, through the exploration of multiple network architectures, we were able to obtain insights as to the role each transcription factor plays in the overall response and their overall redundancy in the organism's response to external perturbations. Thus, the LCA along with the proposed analysis technique is a valuable tool for identifying the possible architectures and mechanisms underlying the transcriptional response.

  3. Feasibility of using linearly polarized rotating birdcage transmitters and close-fitting receive arrays in MRI to reduce SAR in the vicinity of deep brain simulation implants.

    PubMed

    Golestanirad, Laleh; Keil, Boris; Angelone, Leonardo M; Bonmassar, Giorgio; Mareyam, Azma; Wald, Lawrence L

    2017-04-01

    MRI of patients with deep brain stimulation (DBS) implants is strictly limited due to safety concerns, including high levels of local specific absorption rate (SAR) of radiofrequency (RF) fields near the implant and related RF-induced heating. This study demonstrates the feasibility of using a rotating linearly polarized birdcage transmitter and a 32-channel close-fit receive array to significantly reduce local SAR in MRI of DBS patients. Electromagnetic simulations and phantom experiments were performed with generic DBS lead geometries and implantation paths. The technique was based on mechanically rotating a linear birdcage transmitter to align its zero electric-field region with the implant while using a close-fit receive array to significantly increase signal to noise ratio of the images. It was found that the zero electric-field region of the transmitter is thick enough at 1.5 Tesla to encompass DBS lead trajectories with wire segments that were up to 30 degrees out of plane, as well as leads with looped segments. Moreover, SAR reduction was not sensitive to tissue properties, and insertion of a close-fit 32-channel receive array did not degrade the SAR reduction performance. The ensemble of rotating linear birdcage and 32-channel close-fit receive array introduces a promising technology for future improvement of imaging in patients with DBS implants. Magn Reson Med 77:1701-1712, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  4. Controllable in-situ cell electroporation with cell positioning and impedance monitoring using micro electrode array

    PubMed Central

    Guo, Xiaoliang; Zhu, Rong

    2016-01-01

    This paper reports a novel microarray chip for in-situ, real-time and selective electroporation on individual cells integrated with cell positioning and impedance monitoring. An array of quadrupole-electrode units (termed positioning electrodes) and pairs of planar center electrodes located at the centers of each quadrupole-electrode unit were fabricated on the chip. The positioning electrodes are used to trap and position living cells onto the center electrodes based on negative dielectrophoresis (nDEP). The center electrodes are used for in-situ cell electroporation, and also used to measure cell impedance for monitoring cellular dynamics in real time. Controllably selective electroporation and electrical measurement on the cells in array are realized. We present an evidence of selective electroporation through use of fluorescent dyes. Subsequently we use in-situ and real-time impedance measurement to monitor the process, which demonstrates the dynamic behavior of the cell electroporation. Finally, we show the use of this device to perform successful transfection onto individual HeLa cells with vector DNA encoding a green fluorescent. PMID:27507603

  5. The impact of solar cell technology on planar solar array performance

    NASA Technical Reports Server (NTRS)

    Mills, Michael W.; Kurland, Richard M.

    1989-01-01

    The results of a study into the potential impact of advanced solar cell technologies on the characteristics (weight, cost, area) of typical planar solar arrays designed for low, medium and geosynchronous altitude earth orbits are discussed. The study considered planar solar array substrate designs of lightweight, rigid-panel graphite epoxy and ultra-lightweight Kapton. The study proposed to answer the following questions: Do improved cell characteristics translate into array-level weight, size and cost improvements; What is the relative importance of cell efficiency, weight and cost with respect to array-level performance; How does mission orbital environment affect array-level performance. Comparisons were made at the array level including all mechanisms, hinges, booms, and harnesses. Array designs were sized to provide 5kW of array power (not spacecraft bus power, which is system dependent but can be scaled from given values). The study used important grass roots issues such as use of the GaAs radiation damage coefficients as determined by Anspaugh. Detailed costing was prepared, including cell and cover costs, and manufacturing attrition rates for the various cell types.

  6. Screening of Carotenoids in Tomato Fruits by Using Liquid Chromatography with Diode Array-Linear Ion Trap Mass Spectrometry Detection.

    PubMed

    Gentili, Alessandra; Caretti, Fulvia; Ventura, Salvatore; Pérez-Fernández, Virginia; Venditti, Alessandro; Curini, Roberta

    2015-08-26

    This paper presents an analytical strategy for a large-scale screening of carotenoids in tomato fruits by exploiting the potentialities of the triple quadrupole-linear ion trap hybrid mass spectrometer (QqQLIT). The method involves separation on C30 reversed-phase column and identification by means of diode array detection (DAD) and atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). The authentic standards of six model compounds were used to optimize the separative conditions and to predict the chromatographic behavior of untargeted carotenoids. An information dependent acquisition (IDA) was performed with (i) enhanced-mass scan (EMS) as the survey scan, (ii) enhanced-resolution (ER) scan to obtain the exact mass of the precursor ions (16-35 ppm), and (iii) enhanced product ion (EPI) scan as dependent scan to obtain structural information. LC-DAD-multiple reaction monitoring (MRM) chromatograms were also acquired for the identification of targeted carotenoids occurring at low concentrations; for the first time, the relative abundance between the MRM transitions (ion ratio) was used as an extra tool for the MS distinction of structural isomers and the related families of geometrical isomers. The whole analytical strategy was high-throughput, because a great number of experimental data could be acquired with few analytical steps, and cost-effective, because only few standards were used; when applied to characterize some tomato varieties ('Tangerine', 'Pachino', 'Datterino', and 'Camone') and passata of 'San Marzano' tomatoes, our method succeeded in identifying up to 44 carotenoids in the 'Tangerine'" variety.

  7. The glycosylphosphatidylinositol-PLC in Trypanosoma brucei forms a linear array on the exterior of the flagellar membrane before and after activation.

    PubMed

    Hanrahan, Orla; Webb, Helena; O'Byrne, Robert; Brabazon, Elaine; Treumann, Achim; Sunter, Jack D; Carrington, Mark; Voorheis, H Paul

    2009-06-01

    Bloodstream forms of Trypanosoma brucei contain a glycosylphosphatidylinositol-specific phospholipase C (GPI-PLC) that cleaves the GPI-anchor of the variable surface glycoprotein (VSG). Its location in trypanosomes has been controversial. Here, using confocal microscopy and surface labelling techniques, we show that the GPI-PLC is located exclusively in a linear array on the outside of the flagellar membrane, close to the flagellar attachment zone, but does not co-localize with the flagellar attachment zone protein, FAZ1. Consequently, the GPI-PLC and the VSG occupy the same plasma membrane leaflet, which resolves the topological problem associated with the cleavage reaction if the VSG and the GPI-PLC were on opposite sides of the membrane. The exterior location requires the enzyme to be tightly regulated to prevent VSG release under basal conditions. During stimulated VSG release in intact cells, the GPI-PLC did not change location, suggesting that the release mechanism involves lateral diffusion of the VSG in the plane of the membrane to the fixed position of the GPI-PLC.

  8. Fiber optic-linear array detection spectrophotometry in combination with dispersive liquid-liquid microextraction for simultaneous preconcentration and determination of palladium and cobalt.

    PubMed

    Shokoufi, N; Shemirani, F; Assadi, Y

    2007-08-06

    A new combined method including fiber optic-linear array detection spectrophotometry (FO-LADS) and dispersive liquid-liquid microextraction (DLLME) was developed using a cylindrical micro-cell for simultaneous preconcentration and determination of different species. DLLME and FO-LADS methods have good matching conditions for being combined since FO-LADS is a suitable method for the determination of analytes in low volume of the remained phase obtained after DLLME. DLLME technique was successfully used as a sample preparation method. In this preconcentration method, an appropriate mixture of ethanol (the disperser solvent) and 1,2-dichlorobenzene (the extraction solvent) was injected rapidly into the water sample containing palladium and cobalt after complex formation using 1-(2-pyridylazo)-2-naphthol (PAN) reagent. After phase separation, 50 microL of the sedimented phase containing enriched analytes was determined by FO-LADS. The ordinary and first derivative absorption spectra were obtained for optimization and simultaneous determination of palladium and cobalt, respectively. Under the optimum conditions, the calibration graphs were linear in the range of 2-100 microg L(-1) and 1-70 microg L(-1) with detection limit of 0.25 microg L(-1) and 0.2 microg L(-1) for palladium and cobalt, respectively. The relative standard deviations (R.S.D.s, n = 5) were lower than 4%. The enhancement factors of 162 and 165 were obtained for palladium and cobalt, respectively. The proposed method was compared with other methods and applied to the analysis of several real and synthetic samples with satisfactory results.

  9. Microlens array induced light absorption enhancement in polymer solar cells

    SciTech Connect

    Chen, Yuqing; Elshobaki, Moneim; Ye, Zhuo; Park, Joong-Mok; Noack, Max A.; Ho, Kai-Ming; Chaudhary, Sumit

    2013-01-24

    Over the last decade, polymer solar cells (PSCs) have attracted a lot of attention and highest power conversion efficiencies (PCE) are now close to 10%. Here we employ an optical structure – the microlens array (MLA) – to increase light absorption inside the active layer, and PCE of PSCs increased even for optimized devices. Normal incident light rays are refracted at the MLA and travel longer optical paths inside the active layers. Two PSC systems – poly(3-hexylthiophene-2,5-diyl):(6,6)-phenyl C61 butyric acid methyl ester (P3HT:PCBM) and poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:(6,6)-phenyl C71 butyric acid methyl ester (PCDTBT:PC70BM) – were investigated. In the P3HT:PCBM system, MLA increased the absorption, absolute external quantum efficiency, and the PCE of an optimized device by [similar]4.3%. In the PCDTBT:PC70BM system, MLA increased the absorption, absolute external quantum efficiency, and PCE by more than 10%. In addition, simulations incorporating optical parameters of all structural layers were performed and they support the enhancement of absorption in the active layer with the assistance of MLA. Our results show that utilizing MLA is an effective strategy to further increase light absorption in PSCs, in which optical losses account for [similar]40% of total losses. MLA also does not pose materials processing challenges to the active layers since it is on the other side of the transparent substrate.

  10. Cell pairing using a dielectrophoresis-based device with interdigitated array electrodes.

    PubMed

    Şen, Mustafa; Ino, Kosuke; Ramón-Azcón, Javier; Shiku, Hitoshi; Matsue, Tomokazu

    2013-09-21

    We present a chip device with an array of 900 gourd-shaped microwells designed to pair single cells of different types. The device consists of interdigitated array (IDA) electrodes and uses positive dielectrophoresis to trap cells within the microwells. Each side of a microwell is on a different comb of the IDA, so that cells of different types are trapped on opposite sides of the microwells, leading to close cell pairing. Using this device, a large number of cell pairs can be formed easily and rapidly, making it a highly attractive tool for controllable cell pairing in a range of biological applications.

  11. Label-free enumeration of colorectal cancer cells from lymphocytes performed at a high cell-loading density by using interdigitated ring-array microelectrodes.

    PubMed

    Xing, Xiaoxing; Poon, Randy Y C; Wong, Cesar S C; Yobas, Levent

    2014-11-15

    We report the label-free enumeration of human colorectal-carcinoma cells from blood lymphocytes by using interdigitated ring-array microelectrodes; this enumeration was based on the dielectrophoretic selection of cells. Because of the novel design of the device, a continuous flow of cells is uniformly distributed into parallel streams through 300 rings (~40 μm in diameter each) that are integrated into the electrode digits. Using this array, 82% of cancer cells were recovered and 99% of blood lymphocytes were removed. Most of the cancer cells recovered were viable (94%) and could be cultivated for >8 days, during which period they retained their normal cell morphology and proliferation rates. The recovery rate correlated closely with cancer-cell loadings in spiked samples and this relationship was linear over a range of at least 2 orders of magnitude. Importantly, because of the 3D structure of the rings, these results were obtained at a high cell-loading concentration (10(7)cells/mL). The rings could be further optimized for use in accurate label-free identification and measurement of circulating tumor cells in cancer research and disease management.

  12. Patterning pallet arrays for cell selection based on high-resolution measurements of fluorescent biosensors.

    PubMed

    Shadpour, Hamed; Zawistowski, Jon S; Herman, Annadele; Hahn, Klaus; Allbritton, Nancy L

    2011-06-24

    Pallet arrays enable cells to be separated while they remain adherent to a surface and provide a much greater range of cell selection criteria relative to that of current technologies. However there remains a need to further broaden cell selection criteria to include dynamic intracellular signaling events. To demonstrate the feasibility of measuring cellular protein behavior on the arrays using high resolution microscopy, the surfaces of individual pallets were modified to minimize the impact of scattered light at the pallet edges. The surfaces of the three-dimensional pallets on an array were patterned with a coating such as fibronectin using a customized stamping tool. Micropatterns of varying shape and size were printed in designated regions on the pallets in single or multiple steps to demonstrate the reliability and precision of patterning molecules on the pallet surface. Use of a fibronectin matrix stamped at the center of each pallet permitted the localization of H1299 and mouse embryonic fibroblast (MEF) cells to the pallet centers and away from the edges. Compared to pallet arrays with fibronectin coating the entire top surface, arrays with a central fibronectin pattern increased the percentage of cells localized to the pallet center by 3-4-fold. Localization of cells to the pallet center also enabled the physical separation of cells from optical artifacts created by the rough pallet side walls. To demonstrate the measurement of dynamic intracellular signaling on the arrays, fluorescence measurements of high spatial resolution were performed using a RhoA GTPase biosensor. This biosensor utilized fluorescence resonance energy transfer (FRET) between cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) to measure localized RhoA activity in cellular ruffles at the cell periphery. These results demonstrated the ability to perform spatially resolved measurements of fluorescence-based sensors on the pallet arrays. Thus, the patterned pallet arrays

  13. Patterning pallet arrays for cell selection based on high-resolution measurements of fluorescent biosensors

    PubMed Central

    Shadpour, Hamed; Zawistowski, Jon S.; Herman, Annadele; Hahn, Klaus; Allbritton, Nancy L.

    2011-01-01

    Pallet arrays enable cells to be separated while they remain adherent to a surface and provide a much greater range of cell selection criteria relative to that of current technologies. However there remains a need to further broaden cell selection criteria to include dynamic intracellular signaling events. To demonstrate the feasibility of measuring cellular protein behavior on the arrays using high resolution microscopy, the surfaces of individual pallets were modified to minimize the impact of scattered light at the pallet edges. The surfaces of the three-dimensional pallets on an array were patterned with a coating such as fibronectin using a customized stamping tool. Micropatterns of varying shape and size were printed in designated regions on the pallets in single or multiple steps to demonstrate the reliability and precision of patterning molecules on the pallet surface. Use of a fibronectin matrix stamped at the center of each pallet permitted the localization of H1299 and mouse embryonic fibroblast (MEF) cells to the pallet centers and away from the edges. Compared to pallet arrays with fibronection coating the entire top surface, arrays with a central fibronectin pattern increased the percentage of cells localized to the pallet center by 3-4 fold. Localization of cells to the pallet center also enabled the physical separation of cells from optical artifacts created by the rough pallet side walls. To demonstrate the measurement of dynamic intracellular signaling on the arrays, fluorescence measurements of high spatial resolution were performed using a RhoA GTPase biosensor. This biosensor utilized fluorescence resonance energy transfer (FRET) between cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) to measure localized RhoA activity in cellular ruffles at the cell periphery. These results demonstrated the ability to perform spatially resolved measurements of fluorescence-based sensors on the pallet arrays. Thus, the patterned pallet

  14. Si-APD linear-array x-ray detector with 10-100 μm spatial and sub-nanosecond time resolution

    SciTech Connect

    Kishimoto, S. Haruki, R.; Mitsui, T.; Yoda, Y.; Shimazaki, S.; Saito, M.; Ikeno, M.; Tanaka, M.

    2016-07-27

    We developed a silicon avalanche photodiode (Si-APD) linear-array detector to be used for time-resolved X-ray scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 × 200 μm{sup 2}) with a pixel pitch of 150 μm and a depletion depth of 10 μm. The multichannel scaler counted X-ray pulses over continuous 2046 time bins for every 0.5 ns and recorded a time spectrum at each pixel with a time resolution of 0.5 ns (FWHM) for 8.0 keV X-rays. Using the detector system, we were able to observe X-ray peaks clearly separated with 2 ns interval in the multibunch-mode operation of the Photon Factory ring. The small-angle X-ray scattering for polyvinylidene fluoride film was also observed with the detector.

  15. Nuclear resonant scattering measurements on {sup 57}Fe by multichannel scaling with a 64-pixel silicon avalanche photodiode linear-array detector

    SciTech Connect

    Kishimoto, S. Haruki, R.; Mitsui, T.; Yoda, Y.; Taniguchi, T.; Shimazaki, S.; Ikeno, M.; Saito, M.; Tanaka, M.

    2014-11-15

    We developed a silicon avalanche photodiode (Si-APD) linear-array detector for use in nuclear resonant scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 × 200 μm{sup 2}) with a pixel pitch of 150 μm and depletion depth of 10 μm. An ultrafast frontend circuit allows the X-ray detector to obtain a high output rate of >10{sup 7} cps per pixel. High-performance integrated circuits achieve multichannel scaling over 1024 continuous time bins with a 1 ns resolution for each pixel without dead time. The multichannel scaling method enabled us to record a time spectrum of the 14.4 keV nuclear radiation at each pixel with a time resolution of 1.4 ns (FWHM). This method was successfully applied to nuclear forward scattering and nuclear small-angle scattering on {sup 57}Fe.

  16. Nuclear resonant scattering measurements on (57)Fe by multichannel scaling with a 64-pixel silicon avalanche photodiode linear-array detector.

    PubMed

    Kishimoto, S; Mitsui, T; Haruki, R; Yoda, Y; Taniguchi, T; Shimazaki, S; Ikeno, M; Saito, M; Tanaka, M

    2014-11-01

    We developed a silicon avalanche photodiode (Si-APD) linear-array detector for use in nuclear resonant scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 × 200 μm(2)) with a pixel pitch of 150 μm and depletion depth of 10 μm. An ultrafast frontend circuit allows the X-ray detector to obtain a high output rate of >10(7) cps per pixel. High-performance integrated circuits achieve multichannel scaling over 1024 continuous time bins with a 1 ns resolution for each pixel without dead time. The multichannel scaling method enabled us to record a time spectrum of the 14.4 keV nuclear radiation at each pixel with a time resolution of 1.4 ns (FWHM). This method was successfully applied to nuclear forward scattering and nuclear small-angle scattering on (57)Fe.

  17. Characteristics of arc currents on a negatively biased solar cell array in a plasma

    NASA Technical Reports Server (NTRS)

    Snyder, D. B.

    1984-01-01

    The time dependence of the emitted currents during arcing on solar cell arrays is being studied. The arcs are characterized using three parameters: the voltage change of the array during the arc (i.e., the charge lost), the peak current during the arc, and the time constant describing the arc current. This paper reports the dependence of these characteristics on two array parameters, the interconnect bias voltage and the array capacitance to ground. It was found that the voltage change of the array during an arc is nearly equal to the bias voltage. The array capacitance, on the other hand, influences both the peak current and the decay time constant of the arc. Both of these characteristics increase with increasing capacitance.

  18. Linear array measurements of enhanced dynamic wedge and treatment planning system (TPS) calculation for 15 MV photon beam and comparison with electronic portal imaging device (EPID) measurements.

    PubMed

    Petrovic, Borislava; Grzadziel, Aleksandra; Rutonjski, Laza; Slosarek, Krzysztof

    2010-09-01

    Enhanced dynamic wedges (EDW) are known to increase drastically the radiation therapy treatment efficiency. This paper has the aim to compare linear array measurements of EDW with the calculations of treatment planning system (TPS) and the electronic portal imaging device (EPID) for 15 MV photon energy. The range of different field sizes and wedge angles (for 15 MV photon beam) were measured by the linear chamber array CA 24 in Blue water phantom. The measurement conditions were applied to the calculations of the commercial treatment planning system XIO CMS v.4.2.0 using convolution algorithm. EPID measurements were done on EPID-focus distance of 100 cm, and beam parameters being the same as for CA24 measurements. Both depth doses and profiles were measured. EDW linear array measurements of profiles to XIO CMS TPS calculation differ around 0.5%. Profiles in non-wedged direction and open field profiles practically do not differ. Percentage depth doses (PDDs) for all EDW measurements show the difference of not more than 0.2%, while the open field PDD is almost the same as EDW PDD. Wedge factors for 60 deg wedge angle were also examined, and the difference is up to 4%. EPID to linear array differs up to 5%. The implementation of EDW in radiation therapy treatments provides clinicians with an effective tool for the conformal radiotherapy treatment planning. If modelling of EDW beam in TPS is done correctly, a very good agreement between measurements and calculation is obtained, but EPID cannot be used for reference measurements.

  19. Self-assembled two-dimensional thermoresponsive microgel arrays for cell growth/detachment control.

    PubMed

    Xia, Yongqing; He, Xinlong; Cao, Meiwen; Wang, Xiaojuan; Sun, Yawei; He, Hua; Xu, Hai; Lu, Jian Ren

    2014-11-10

    Monodisperse poly(N-isopropylacrylamide-styrene) (PNIPAAmSt) microgels with different St/NIPAAm ratios have been synthesized via a one-step surfactant-free emulsion polymerization process. The resulting microgel dispersions were used to fabricate 2D arrays on the surface of silicon wafers/glass coverslips through dip coating. The thermal responsiveness of the PNIPAAmSt microgel arrays was examined by spectroscopic ellipsometry and the results unraveled that the thermoresponsive behavior of the arrays was highly consistent with the microgels dispersed in the bulk, showing high dependence on the content of styrene. The structure of the films varied from nonclose-packed 2D arrays to close-packed 2D arrays, depending on both properties of the microgels and array fabrication conditions. When the weight ratio of styrene was below 40%, the microgel arrays demonstrated effective control for cell growth and detachment across their volume phase transition temperatures (around 28 °C). The extent of swelling of the microgels was the key factor to determine whether the cells could detach from the film easily. For the rather close-packed 2D arrays prepared by the same kind of PNIPAAmSt microgels, the gaps between microgel particles showed no obvious effect on the rate of cell detachment.

  20. Integration of TiO2 nanotube arrays into solid-state dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Bandara, J.; Shankar, K.; Basham, J.; Wietasch, H.; Paulose, M.; Varghese, O. K.; Grimes, C. A.; Thelakkat, M.

    2011-02-01

    In this investigation, transparent TiO2 nanotube arrays prepared on a FTO substrate are employed as 1D nanostructures providing elongated direct pathways for electron transport and collection in solid-state dye-sensitized solar cell (SDSC). Donor-antenna (D-A) dyes provide an exciting route for improving the light harvesting efficiency in dye sensitized solar cells owing to their high molar extinction coefficients and the effective spatial separation of charges in the charge-separated state. Hence in this study we fabricated SDSC devices with different thicknesses of transparent TiO2 nanotube array electrodes sensitized with Ru-(II)-donor-antenna dye and spiro-OMeTAD as a hole conductor. At AM 1.5 G, 100 mW/cm2 illumination intensity, a power conversion efficiency of 1.94% was achieved when the TiO2 nanotubes are initially subjected to TiCl4 treatment. Furthermore, a linear increase in the cell current without loss in fill factor is observed for increasing length of TiO2 nanotubes. The structural and morphological characteristics of the transparent TiO2 nanotube arrays as well as the optimal conditions for the fabrication of SDSCs with transparent TiO2 nanotubes on FTO glass are reported.

  1. Detection of ≥1Mb microdeletions and microduplications in a single cell using custom oligonucleotide arrays.

    PubMed

    Bi, Weimin; Breman, Amy; Shaw, Chad A; Stankiewicz, Pawel; Gambin, Tomasz; Lu, Xinyan; Cheung, Sau Wai; Jackson, Laird G; Lupski, James R; Van den Veyver, Ignatia B; Beaudet, Arthur L

    2012-01-01

    High resolution detection of genomic copy number abnormalities in a single cell is relevant to preimplantation genetic diagnosis and potentially to noninvasive prenatal diagnosis. Our objective is to develop a reliable array comparative genomic hybridization (CGH) platform to detect genomic imbalances as small as ~1Mb ina single cell. We empirically optimized the conditions for oligonucleotide-based array CGH using single cells from multiple lymphoblastoid cell lines with known copy number abnormalities. To improve resolution, we designed custom arrays with high density probes covering clinically relevant genomic regions. The detection of megabase-sized copy number variations (CNVs) in a single cell was influenced by the number of probes clustered in the interrogated region. Using our custom array, we reproducibly detected multiple chromosome abnormalities including trisomy 21, a 1.2Mb Williams syndrome deletion, and a 1.3Mb CMT1A duplication. Replicate analyses yielded consistent results. Aneuploidy and genomic imbalances with CNVs as small as 1.2Mb in a single cell are detectable by array CGH using arrays with high-density coverage in the targeted regions. This approach has the potential to be applied for preimplantation genetic diagnosis to detect aneuploidy and common microdeletion/duplication syndromes and for noninvasive prenatal diagnosis if single fetal cells can be isolated. © 2012 John Wiley & Sons, Ltd.

  2. Human papillomavirus genotyping by Linear Array and Next-Generation Sequencing in cervical samples from Western Mexico.

    PubMed

    Flores-Miramontes, María Guadalupe; Torres-Reyes, Luis Alberto; Alvarado-Ruíz, Liliana; Romero-Martínez, Salvador Angel; Ramírez-Rodríguez, Verenice; Balderas-Peña, Luz María Adriana; Vallejo-Ruíz, Verónica; Piña-Sánchez, Patricia; Cortés-Gutiérrez, Elva Irene; Jave-Suárez, Luis Felipe; Aguilar-Lemarroy, Adriana

    2015-10-06

    The Linear Array® (LA) genotyping test is one of the most used methodologies for Human papillomavirus (HPV) genotyping, in that it is able to detect 37 HPV genotypes and co-infections in the same sample. However, the assay is limited to a restricted number of HPV, and sequence variations in the detection region of the HPV probes could give false negatives results. Recently, 454 Next-Generation sequencing (NGS) technology has been efficiently used also for HPV genotyping; this methodology is based on massive sequencing of HPV fragments and is expected to be highly specific and sensitive. In this work, we studied HPV prevalence in cervixes of women in Western Mexico by LA and confirmed the genotypes found by NGS. Two hundred thirty three cervical samples from women Without cervical lesions (WCL, n = 48), with Cervical intraepithelial neoplasia grade 1 (CIN I, n = 98), or with Cervical cancer (CC, n = 87) were recruited, DNA was extracted, and HPV positivity was determined by PCR amplification using PGMY09/11 primers. All HPV- positive samples were genotyped individually by LA. Additionally, pools of amplicons from the PGMY-PCR products were sequenced using 454 NGS technology. Results obtained by NGS were compared with those of LA for each group of samples. We identified 35 HPV genotypes, among which 30 were identified by both technologies; in addition, the HPV genotypes 32, 44, 74, 102 and 114 were detected by NGS. These latter genotypes, to our knowledge, have not been previously reported in Mexican population. Furthermore, we found that LA did not detect, in some diagnosis groups, certain HPV genotypes included in the test, such as 6, 11, 16, 26, 35, 51, 58, 68, 73, and 89, which indicates possible variations at the species level. There are HPV genotypes in Mexican population that cannot be detected by LA, which is, at present, the most complete commercial genotyping test. More studies are necessary to determine the impact of HPV-44, 74, 102 and 114 on the risk of

  3. Method of making silicon solar cell array. [and mounting on flexible substrate

    NASA Technical Reports Server (NTRS)

    Forestieri, A. F.; Broder, J. D.; Bernatowicz, D. T. (Inventor)

    1973-01-01

    A heat sealable transparent plastic film, such as a flourinated ethylene propylene copolymer, is used both as a cover material and as an adhesive for mounting a solar cell array to a flexible substrate.

  4. Photovoltaic cell and array technology development for future unique NASA missions

    NASA Technical Reports Server (NTRS)

    Bailey, S.; Curtis, H.; Piszczor, M.; Surampudi, R.; Hamilton, T.; Rapp, D.; Stella, P.; Mardesich, N.; Mondt, J.; Bunker, R.; Nesmith, B.; Gaddy, E.; Marvin, D.; Kazmerski, L.

    2002-01-01

    A technology review committee from NASA, the U.S. Department of Energy (DOE), and the Air Force Research Lab, was formed to assess solar cell and array technologies required for future NASA science missions.

  5. Photovoltaic cell and array technology development for future unique NASA missions

    NASA Technical Reports Server (NTRS)

    Bailey, S.; Curtis, H.; Piszczor, M.; Surampudi, R.; Hamilton, T.; Rapp, D.; Stella, P.; Mardesich, N.; Mondt, J.; Bunker, R.; hide

    2002-01-01

    A technology review committee from NASA, the U.S. Department of Energy (DOE), and the Air Force Research Lab, was formed to assess solar cell and array technologies required for future NASA science missions.

  6. Deformable L-shaped microwell array for trapping pairs of heterogeneous cells

    NASA Astrophysics Data System (ADS)

    Lee, Gi-Hun; Kim, Sung-Hwan; Kang, AhRan; Takayama, Shuichi; Lee, Sang-Hoon; Park, Joong Yull

    2015-03-01

    To study cell-to-cell interactions, there has been a continuous demand on developing microsystems for trapping pairs of two different cells in microwell arrays. Here, we propose an L-shaped microwell (L-microwell) array that relies on the elasticity of a polydimethylsiloxane (PDMS) substrate for trapping and pairing heterogeneous cells. We designed an L-microwell suitable for trapping single cell in each branch via stretching/releasing the PDMS substrate, and also performed 3D time-dependent diffusion simulations to visualize how cell-secreted molecules diffuse in the L-microwell and communicate with the partner cell. The computational results showed that the secreted molecule first contacted the partner cell after 35 min, and the secreted molecule fully covered the partner cell in 4 h (when referenced to 10% of the secreted molecular concentration). The molecules that diffused to the outside of the L-microwell were significantly diluted by the bulk solution, which prevented unwanted cellular communication between neighboring L-microwells. We produced over 5000 cell pairs in one 2.25 cm2 array with about 30 000 L-microwells. The proposed L-microwell array offers a versatile and convenient cell pairing method to investigate cell-to-cell interactions in, for example, cell fusion, immune reactions, and cancer metastasis.

  7. Hybrid triple-level-cell/multi-level-cell NAND flash storage array with chip exchangeable method

    NASA Astrophysics Data System (ADS)

    Hachiya, Shogo; Johguchi, Koh; Miyaji, Kousuke; Takeuchi, Ken

    2014-01-01

    This paper proposes a mix-and-match design method for triple level cell (TLC)/multi level cell (MLC) NAND flash hybrid and exchangeable storage arrays. A TLC-NAND flash provides an low cost and high capacity memory solution. However the reliability and access latency of TLC NAND flash are degraded from MLC NAND flash. Additionally, the block unit write is preferable for TLC NAND flash since the write order is complicated due to narrow data margin and write disturbance. The proposed solution combines TLC and MLC NAND flash memories for a storage array. To reduce access to TLC NAND flash, the stored data is screened and only the static frozen data are stored into TLC NAND flash with a Round-Robin frozen data collection algorithm (RR-FDCA). Furthermore, the proposed chip exchanging method extends the solid-state drive (SSD) lifetime without system suspending. As a result, in spite of moderate characteristics of TLC NAND flash, the proposed storage array can achieve 29% write energy saving and 56% write performance enhancement with 17% cost reduction, compared with the conventional MLC-only SSD.

  8. Disturbance characteristics of half-selected cells in a cross-point resistive switching memory array

    NASA Astrophysics Data System (ADS)

    Chen, Zhe; Li, Haitong; Chen, Hong-Yu; Chen, Bing; Liu, Rui; Huang, Peng; Zhang, Feifei; Jiang, Zizhen; Ye, Hongfei; Gao, Bin; Liu, Lifeng; Liu, Xiaoyan; Kang, Jinfeng; Wong, H.-S. Philip; Yu, Shimeng

    2016-05-01

    Disturbance characteristics of cross-point resistive random access memory (RRAM) arrays are comprehensively studied in this paper. An analytical model is developed to quantify the number of pulses (#Pulse) the cell can bear before disturbance occurs under various sub-switching voltage stresses based on physical understanding. An evaluation methodology is proposed to assess the disturb behavior of half-selected (HS) cells in cross-point RRAM arrays by combining the analytical model and SPICE simulation. The characteristics of cross-point RRAM arrays such as energy consumption, reliable operating cycles and total error bits are evaluated by the methodology. A possible solution to mitigate disturbance is proposed.

  9. Optimization of Germanium Cell Arrays in Tungsten Emitter-based Solar TPV Systems

    NASA Astrophysics Data System (ADS)

    Datas, A.; Algora, C.; Corregidor, V.; Martín, D.; Bett, A. W.; Dimroth, F.; Fernández, J.

    2007-02-01

    This work presents a simulation study to find the best cell array configuration which leads to the maximum thermophotovoltaic (TPV) conversion efficiency in a specific solar thermophotovoltaic (STPV) system. First, the optical and electrical device parameters have been extracted from germanium TPV cells working at 25°C. Then, a cell model consisting of two parallel diodes and two resistances (series and shunt) has been developed for its use in SPICE® software. The parameters of this model have been obtained from the fitting of dark the I-V curve from germanium cells. In addition, the cell photocurrent density has been calculated by integrating the measured spectral response (SR) of the cells under a typical tungsten emission spectrum at different system view factors (VF), i.e. ratios of power density on the emitter surface to the power density on the receptor surface. Changing the VF leads to different light power densities reaching the receptor area for a fixed emitter temperature. Different emitter temperatures have also been taken into account in this study. They are directly related to the different re-emitting efficiencies expected for the concentrator-emitter system in a real STPV system. Finally, the overall array efficiency has been estimated for different array configurations working from 0.01 to the maximum view factor for each array configuration, which depends on the geometry and the number of cells in the array. The cell temperature effect on the efficiency has been also considered from the measured cells in flash equipment.

  10. Supporting Structures for Flat Solar-Cell Arrays

    NASA Technical Reports Server (NTRS)

    Wilson, A. H.

    1986-01-01

    Strong supporting structures for flat solar photovoltaic arrays built with such commonly available materials as wood and galvanized steel sheet. Structures resist expected static loads from snow and ice as well as dynamic loads from winds and even Earthquake vibrations. Supporting structure uses inexpensive materials. Parts prefabricated to minimize assembly work in field.

  11. Supporting Structures for Flat Solar-Cell Arrays

    NASA Technical Reports Server (NTRS)

    Wilson, A. H.

    1986-01-01

    Strong supporting structures for flat solar photovoltaic arrays built with such commonly available materials as wood and galvanized steel sheet. Structures resist expected static loads from snow and ice as well as dynamic loads from winds and even Earthquake vibrations. Supporting structure uses inexpensive materials. Parts prefabricated to minimize assembly work in field.

  12. The effects of anodization parameters on titania nanotube arrays and dye sensitized solar cells.

    PubMed

    Xie, Z B; Adams, S; Blackwood, D J; Wang, J

    2008-10-08

    Ordered, closely packed, and vertically oriented titania nanotube arrays with lengths exceeding 10 µm were fabricated by anodization of titanium foils. The effects of anodization voltage and time on the microstructural morphology and the photovoltaic performance of dye sensitized solar cells based on the titania nanotube arrays were investigated. On increasing the anodization voltage or time, the increase in active surface area leads to enhanced photovoltaic currents and thereby an overall higher performance of the dye sensitized solar cells. The efficiency enhancement with rising anodization voltage exceeds the increase in the outer surface area of the nanotubes, indicating that the active surface area is further enlarged by a more accessible inner surface of the nanotube arrays grown with a higher anodization voltage. A promising efficiency of 3.67% for dye sensitized solar cells based on anodized titania nanotube arrays was achieved under AM1.5, 100 mW cm(-2) illumination.

  13. Multiscale Study of Plasmonic Scattering and Light Trapping Effect in Silicon Nanowire Array Solar Cells.

    PubMed

    Meng, Lingyi; Zhang, Yu; Yam, ChiYung

    2017-02-02

    Nanometallic structures that support surface plasmons provide new ways to confine light at deep-subwavelength scales. The effect of light scattering in nanowire array solar cells is studied by a multiscale approach combining classical electromagnetic (EM) and quantum mechanical simulations. A photovoltaic device is constructed by integrating a silicon nanowire array with a plasmonic silver nanosphere. The light scatterings by plasmonic element and nanowire array are obtained via classical EM simulations, while current-voltage characteristics and optical properties of the nanowire cells are evaluated quantum mechanically. We found that the power conversion efficiency (PCE) of photovoltaic device is substantially improved due to the local field enhancement of the plasmonic effect and light trapping by the nanowire array. In addition, we showed that there exists an optimal nanowire number density in terms of optical confinement and solar cell PCE.

  14. Cell integrated multi-junction thermocouple array for solid oxide fuel cell temperature sensing: N+1 architecture

    NASA Astrophysics Data System (ADS)

    Ranaweera, Manoj; Kim, Jung-Sik

    2016-05-01

    Understanding the cell temperature distribution of solid oxide fuel cell (SOFC) stacks during normal operation has multifaceted advantages in performance and degradation studies. Present efforts on measuring temperature from operating SOFCs measure only the gas channel temperature and do not reveal the cell level temperature distribution, which is more important for understanding a cell's performance and its temperature-related degradation. The authors propose a cell-integrated, multi-junction thermocouple array for in-situ cell surface temperature monitoring of an operational SOFC. The proposed thermocouple array requires far fewer numbers of thermoelements than that required by sets of thermocouples for the same number of temperature sensing points. Hence, the proposed array causes lower disturbance to cell performance than thermocouples. The thermoelement array was sputter deposited on the cathode of a commercial SOFC using alumel (Ni:Al:Mn:Si - 95:2:2:1 by wt.) and chromel (Ni:Cr - 90:10 by wt.). The thermocouple array was tested in a furnace over the entire operating temperature range of a typical SOFC. The individual sensing points of the array were shown to measure temperature independently from each other with equivalent accuracy to a thermocouple. Thus, the concept of multi-junction thermocouples is experimentally validated and its stability on a porous SOFC cathode is confirmed.

  15. Tissue matrix arrays for high throughput screening and systems analysis of cell function

    PubMed Central

    Beachley, Vince Z.; Wolf, Matthew T.; Sadtler, Kaitlyn; Manda, Srikanth S.; Jacobs, Heather; Blatchley, Michael; Bader, Joel S.; Pandey, Akhilesh; Pardoll, Drew; Elisseeff, Jennifer H.

    2015-01-01

    Cell and protein arrays have demonstrated remarkable utility in the high-throughput evaluation of biological responses; however, they lack the complexity of native tissue and organs. Here, we describe tissue extracellular matrix (ECM) arrays for screening biological outputs and systems analysis. We spotted processed tissue ECM particles as two-dimensional arrays or incorporated them with cells to generate three-dimensional cell-matrix microtissue arrays. We then investigated the response of human stem, cancer, and immune cells to tissue ECM arrays originating from 11 different tissues, and validated the 2D and 3D arrays as representative of the in vivo microenvironment through quantitative analysis of tissue-specific cellular responses, including matrix production, adhesion and proliferation, and morphological changes following culture. The biological outputs correlated with tissue proteomics, and network analysis identified several proteins linked to cell function. Our methodology enables broad screening of ECMs to connect tissue-specific composition with biological activity, providing a new resource for biomaterials research and translation. PMID:26480475

  16. Array of Hall Effect Sensors for Linear Positioning of a Magnet Independently of Its Strength Variation. A Case Study: Monitoring Milk Yield during Milking in Goats

    PubMed Central

    García-Diego, Fernando-Juan; Sánchez-Quinche, Angel; Merello, Paloma; Beltrán, Pedro; Peris, Cristófol

    2013-01-01

    In this study we propose an electronic system for linear positioning of a magnet independent of its modulus, which could vary because of aging, different fabrication process, etc. The system comprises a linear array of 24 Hall Effect sensors of proportional response. The data from all sensors are subject to a pretreatment (normalization) by row (position) making them independent on the temporary variation of its magnetic field strength. We analyze the particular case of the individual flow in milking of goats. The multiple regression analysis allowed us to calibrate the electronic system with a percentage of explanation R2 = 99.96%. In our case, the uncertainty in the linear position of the magnet is 0.51 mm that represents 0.019 L of goat milk. The test in farm compared the results obtained by direct reading of the volume with those obtained by the proposed electronic calibrated system, achieving a percentage of explanation of 99.05%. PMID:23793020

  17. Cell Confinement in Patterned Nanoliter Droplets in a Microwell Array by Wiping

    PubMed Central

    Kang, Lifeng; Hancock, Matthew J.; Brigham, Mark D.; Khademhosseini, Ali

    2009-01-01

    Cell patterning is useful for a variety of biological applications such as tissue engineering and drug discovery. In particular, the ability to localize cells within distinct fluids is beneficial for a variety of applications ranging from microencapsulation to high-throughput analysis. However, despite much progress, cell immobilization and maintenance within patterned microscale droplets remains a challenge. In particular, no method currently exists to rapidly seed cells into microwell arrays in a controllable and reliable manner. In this study, we present simple wiping technique to localize cells within arrays of polymeric microwells. This robust method produces cell seeding densities that vary consistently with microwell geometry and cell concentration. Moreover, we develop a simple theoretical model to accurately predict cell seeding density and seeding efficiency in terms of the design parameters of the microwell array and the cell density. This short-term cell patterning approach is an enabling tool to develop new high-throughput screening technologies that utilize microwell arrays containing cells for screening applications. PMID:19585570

  18. Light Weight, Low Cost, High Efficiency Solar Cells for Space Planar Arrays.

    DTIC Science & Technology

    1997-01-01

    replacement for GaAs cells and capable of operating in nominal space environments. 15. Subject Terms Multijunction solar cells , Photovoltaics, Space Power...PL-TR-96-1175 PL-TR- 96-1175 LIGHT WEIGHT, LOW COST, HIGH EFFICIENCY SOLAR CELLS FOR SPACE PLANAR ARRAYS Dr. David Lillington Dr. Terry Cavicchi...Light Weight, Low Cost, High Efficiency Solar Cells for F33615-91-C-2146 Space Planar Arrays 5b. Program Element # 63401F 6. Author(s) 5c.

  19. Light-Weight, Low Cost, High-Efficiency Solar Cells Space Planar Arrays.

    DTIC Science & Technology

    1996-01-01

    PL-TR-96-1007 PL-TR- 96- 1007 LIGHT-WEIGHT, LOW COST, HIGH-EFFICIENCY SOLAR CELLS FOR SPACE PLANAR ARRAYS Michael L. Timmons Research Triangle...Cost, High-Efficiency Solar Cells F33615-91-C-2155 for Space Planar Arrays 5b. Program Element # 62601F 6. Author(s) 5c. Project # 2864 Michael L...GalnAsP cell is markedly better. 48 Figure 5.1. Schematic cross-section of mechanically stacked tandem solar cell . S is the spacing of the interconnect grid

  20. Comparison of the clinical performance of restriction fragment mass polymorphism (RFMP) and Roche linear array HPV test assays for HPV detection and genotyping.

    PubMed

    Lee, Hyo-Pyo; Cho, Woojae; Bae, Jae-Man; Shin, Ji Young; Shin, Soo-Kyung; Hwang, Sun Young; Min, Kyung Tae; Kim, Soo Nyung; Lee, Sun Joo; Kim, Soo-Ok; Yoo, Wang Don; Hong, Sun Pyo

    2013-06-01

    The need for accurate genotyping of human papillomavirus (HPV) infections is becoming increasingly important as HPV is the primary cause of cervical cancer worldwide. The matrix-assisted laser desorption ionization time-of-flight mass spectrometry-based restriction fragment mass polymorphism (RFMP) assay provides accurate, broad-spectrum, high-throughput genotyping of HPV. We evaluated the clinical performance of the RFMP assay compared to a commercially available Roche linear array HPV genotyping test (LA) for detecting and genotyping of HPV. The RFMP assay and the LA were compared for detecting and genotyping HPV among a cohort of 244 liquid-based cytology samples. Overall, 216 specimens (93.1%, κ = 0.86) generated concordant results for the presence or absence of high-risk HPV (HR-HPV) by the two assays. The RFMP assay and the LA assay generated concordant, compatible, and discordant genotyping results for 79.3, 9.9, and 10.8%, respectively. The diagnostic sensitivity and specificity of RFMP and LA for the cervical lesions of squamous cell carcinoma (SCC) were similar, at 92.9 and 85.0% (RFMP) and 92.9 and 83.8% (LA), respectively. In addition, the odds ratio for SCC with HR-HPV positivity estimated by the RFMP assay (73.7, 95% CI: 8.9-3173.3) was higher than the LA assay (67.0, 95% CI: 8.2-2887.0). The RFMP and the LA assays were highly comparable with regard to detection and genotyping analysis of HPV. The sensitivity and specificity of RFMP assay for the detection of HR-HPV in various levels of cervical lesions seems to be valuable in the monitoring of HPV-associated cervical cancer. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. A discrete component low-noise preamplifier readout for a linear (1×16) SiC photodiode array

    NASA Astrophysics Data System (ADS)

    Kahle, Duncan; Aslam, Shahid; Herrero, Federico A.; Waczynski, Augustyn

    2016-09-01

    A compact, low-noise and inexpensive preamplifier circuit has been designed and fabricated to optimally readout a common cathode (1×16) channel 4H-SiC Schottky photodiode array for use in ultraviolet experiments. The readout uses an operational amplifier with 10 pF capacitor in the feedback loop in parallel with a low leakage switch for each of the channels. This circuit configuration allows for reiterative sample, integrate and reset. A sampling technique is given to remove Johnson noise, enabling a femtoampere level readout noise performance. Commercial-off-the-shelf acquisition electronics are used to digitize the preamplifier analog signals. The data logging acquisition electronics has a different integration circuit, which allows the bandwidth and gain to be independently adjusted. Using this readout, photoresponse measurements across the array between spectral wavelengths 200 nm and 370 nm are made to establish the array pixels external quantum efficiency, current responsivity and noise equivalent power.

  2. A Microfluidic Localized, Multiple Cell Culture Array using Vacuum Actuated Cell Seeding: Integrated Anticancer Drug Testing

    PubMed Central

    Gao, Yan; Li, Peng

    2013-01-01

    In this study, we introduced a novel and convenient approach to culture multiple cells in localized arrays of microfluidic chambers using one-step vacuum actuation. In one device, we integrated 8 individually addressable regions of culture chambers, each only requiring one simple vacuum operation to seed cells lines. Four cell lines were seeded in designated regions in one device via sequential injection with high purity (99.9%-100%) and cultured for long-term. The on-chip simultaneous culture of HuT 78, Ramos, PC-3 and C166-GFP cells for 48 h was demonstrated with viabilities of 92%+/−2%, 94%+/−4%, 96%+/−2% and 97%+/−2%, respectively. The longest culture period for C166-GFP cells in this study was 168 h with a viability of 96%+/−10%. Cell proliferation in each individual side channel can be tracked. Mass transport between the main channel and side channels was achieved through diffusion and studied using fluorescein solution. The main advantage of this device is the capability to perform multiple cell-based assays on the same device for better comparative studies. After treating cells with staurosporine or anti-human CD95 for 16 h, the apoptotic cell percentage of HuT 78, CCRF-CEM, PC-3 and Ramos cells were 36%+/−3%, 24%+/−4%, 12%+/−2%, 18%+/−4% for staurosporine, and 63%+/−2%, 45%+/−1%, 3%+/−3%, 27%+/−12% for anti-human CD95, respectively. With the advantages of enhanced integration, ease of use and fabrication, and flexibility, this device will be suitable for long-term multiple cell monitoring and cell based assays. PMID:23813077

  3. Ultra-dense silicon nanowire array solar cells by nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Liu, Pei; Siontas, Stylianos; Zaslavsky, Alexander; Pacifici, Domenico; Ha, Jong-Yoon; Krylyuk, Sergiy; Davydov, Albert

    Nanowire (NW) solar cells have been attracting increasing interest due to their potentially superior light absorption compared to thin bulk films. In order to improve light trapping, we have used nanoimprint lithography (NIL) to fabricate high-density NW arrays with deep sub-micron pitch (P) and diameter (D). We have grown dense vertical arrays of Si axial p - i - n junction NWs of D = 170 nm and P = 500 nm by vapor-liquid-solid epitaxy on seed arrays produced by NIL. The NWs were 9 µm length long with a 5 µm intrinsic section. The NW arrays were planarized using SU-8 photoresist, followed by reactive ion etching to expose the NW tips. Top n-contact was realized by sputter deposition of a transparent 200 nm IZO layer. The nanoimprinted NW array samples measured under AM 1.5 G illumination showed a peak external quantum efficiency of ~8% and internal quantum efficiency of ~90% in the visible spectral range. Three-dimensional finite-difference time-domain simulations of Si NW periodic arrays with varying P confirm the importance of high NW density. Specifically, due to diffractive scattering and light trapping, absorption efficiency close to 100% in the 400-650 nm spectral range is predicted for a Si NW array with an even smaller P = 250 nm, significantly outperforming a blanket Si film of the same thickness. Such pitch values are accessible to NIL and work on such arrays is in progress. National Science Foundation.

  4. Engineering complex tissue-like microgel arrays for evaluating stem cell differentiation

    PubMed Central

    Guermani, Enrico; Shaki, Hossein; Mohanty, Soumyaranjan; Mehrali, Mehdi; Arpanaei, Ayyoob; Gaharwar, Akhilesh K.; Dolatshahi-Pirouz, Alireza

    2016-01-01

    Development of tissue engineering scaffolds with native-like biology and microarchitectures is a prerequisite for stem cell mediated generation of off-the-shelf-tissues. So far, the field of tissue engineering has not full-filled its grand potential of engineering such combinatorial scaffolds for engineering functional tissues. This is primarily due to the many challenges associated with finding the right microarchitectures and ECM compositions for optimal tissue regeneration. Here, we have developed a new microgel array to address this grand challenge through robotic printing of complex stem cell-laden microgel arrays. The developed microgel array platform consisted of various microgel environments that where composed of native-like cellular microarchitectures resembling vascularized and bone marrow tissue architectures. The feasibility of our array system was demonstrated through localized cell spreading and osteogenic differentiation of human mesenchymal stem cells (hMSCs) into complex tissue-like structures. In summary, we have developed a tissue-like microgel array for evaluating stem cell differentiation within complex and heterogeneous cell microenvironments. We anticipate that the developed platform will be used for high-throughput identification of combinatorial and native-like scaffolds for tissue engineering of functional organs. PMID:27465860

  5. Highly efficient ultrathin-film amorphous silicon solar cells on top of imprinted periodic nanodot arrays

    SciTech Connect

    Yan, Wensheng Gu, Min; Tao, Zhikuo; Ong, Thiam Min Brian

    2015-03-02

    The addressing of the light absorption and conversion efficiency is critical to the ultrathin-film hydrogenated amorphous silicon (a-Si:H) solar cells. We systematically investigate ultrathin a-Si:H solar cells with a 100 nm absorber on top of imprinted hexagonal nanodot arrays. Experimental evidences are demonstrated for not only notable silver nanodot arrays but also lower-cost ITO and Al:ZnO nanodot arrays. The measured external quantum efficiency is explained by the simulation results. The J{sub sc} values are 12.1, 13.0, and 14.3 mA/cm{sup 2} and efficiencies are 6.6%, 7.5%, and 8.3% for ITO, Al:ZnO, and silver nanodot arrays, respectively. Simulated optical absorption distribution shows high light trapping within amorphous silicon layer.

  6. High voltage solar cell power generating system for regulated solar array development

    NASA Technical Reports Server (NTRS)

    Levy, E., Jr.; Hoffman, A. C.

    1973-01-01

    A laboratory solar power system regulated by on-panel switches has been delivered for operating high power (3 kw), high voltage (15,000 volt) loads (communication tubes, ion thrusters). The modular system consists of 26 solar arrays, each with an integral light source and cooling system. A typical array contains 2560 series-connected cells. Each light source consists of twenty 500 watt tungsten iodide lamps providing plus or minus 5 per cent uniformity at one solar constant. An array temperature of less than 40 C is achieved using an infrared filter, a water cooled plate, a vacuum hold-down system, and air flushing.

  7. ZnO nanotube waveguide arrays on graphene films for local optical excitation on biological cells

    NASA Astrophysics Data System (ADS)

    Baek, Hyeonjun; Kwak, Hankyul; Song, Minho S.; Ha, Go Eun; Park, Jongwoo; Tchoe, Youngbin; Hyun, Jerome K.; Park, Hye Yoon; Cheong, Eunji; Yi, Gyu-Chul

    2017-04-01

    We report on scalable and position-controlled optical nanoprobe arrays using ZnO nanotube waveguides on graphene films for use in local optical excitation. For the waveguide fabrication, position-controlled and well-ordered ZnO nanotube arrays were grown on chemical vapor deposited graphene films with a submicron patterned mask layer and Au prepared between the interspace of nanotubes. Mammalian cells were cultured on the nanotube waveguide arrays and were locally excited by light illuminated through the nanotubes. Fluorescence and optogenetic signals could be excited through the optical nanoprobes. This method offers the ability to investigate cellular behavior with a high spatial resolution that surpasses the current limitation.

  8. Low molecular weight antigen arrays delete high affinity memory B cells without affecting specific T-cell help.

    PubMed

    Reim, J W; Symer, D E; Watson, D C; Dintzis, R Z; Dintzis, H M

    1996-12-01

    An ongoing, T-cell dependent, secondary antibody response to an epitope can be suppressed in vivo by low molecular weight, soluble polymers, bearing multiple copies of the same epitope. This study illustrates that such suppressive T-cell independent antigen arrays target the epitope-specific, high affinity, memory B cells for long-term functional elimination. Splenocytes from hyperimmune unsuppressed donors, when adoptively transferred into irradiated recipients will readily reconstitute a secondary anti-hapten response after antigenic challenge. No such response was observed with splenocytes transferred from hyperimmune donors suppressed with antigen arrays. The extent of suppression depended on antigen array dose and duration of exposure in the donor animals. The suppressive antigen array carryover from the donors into the recipients was negligible and insufficient to account for the observed suppression. B cells from hyperimmune mice producing high affinity anti-fluorescein antibodies, generated by multiple fluoresceinated ovalbumin (FL-OVA) injections, were helped efficiently by T cells from hyperimmune donors, which were either unsuppressed or suppressed with antigen arrays. Accordingly, help from T cells, specific for the carrier protein remains intact after such suppression. Neither lipopolysaccharide (LPS), nor additional transferred carrier-primed T cells could reverse the unresponsiveness of adoptively transferred splenocytes from suppressed animals. Flow cytometry showed that the number of hapten-specific B cells was markedly reduced after suppression. Collectively, these data show that the long term elimination of an ongoing T-cell dependent antibody response by suppressive exogenous antigen arrays is due to the functional deletion of high affinity, antigen-specific B cells, even in the presence of adequate T-cell help. The long-term nature of such functional deletion strongly suggests physical deletion of the antigen-specific B cell population.

  9. Analytical and numerical study of the buckling of planar linear array deployable structures based on scissor-like element under its own weight

    NASA Astrophysics Data System (ADS)

    Li, Bo; Wang, San-Min; Zhi, Chang-Jian; Xue, Xiang-Zhen; Makis, Viliam

    2017-01-01

    This paper aims at investigating the buckling load of fully deployed linear array deployable structure based on scissor-like element (SLE) under its own weight. The deployable structure has been widely researched both in geometric configurations and structural dynamic characteristics. However, when the number of elements or degree of deployment exceeds the predetermined range, even if there is no external load, deployable structure will automatically collapse under its own weight. To address this issue, this paper derives a new stability model based on linear elastic analysis and energy method to compute the buckling load caused by its own weight for avoiding the structural instability, which can be applied to a linear array deployable structure with n SLEs. In the process of calculation, the first SLE is taken for mechanical analysis and the results are extended to any unit. In the sequel of this process, the scissor deployable structure is equivalent to a uniform solid column and its buckling condition under self-weight is obtained based on the principle of potential energy. Also, the effect of various parameters that affect the instability of the structure, such as the number of elements, bar length and degree of deployment is investigated, and the results of the theoretical analysis are verified through a comparison with the simulation results in ANSYS, which show that the new stability model proposed here can predict the buckling load of scissor deployable structure.

  10. A microneedle array able to inject tens of thousands of cells simultaneously

    NASA Astrophysics Data System (ADS)

    Teichert, Gregory H.; Burnett, Sandra; Jensen, Brian D.

    2013-09-01

    This paper presents a biological microelectromechanical system for injecting foreign particles into thousands of cells simultaneously. The system inserts an array of microneedles into a monolayer of cells, and the foreign particles enter the cells by diffusion. The needle array is fabricated using a series of deep reactive ion etches and produces about 4 million needles that average 1 μm in diameter and 8 μm in length with 10 μm spacing. The insertion of the needles is controlled through a compliant suspension. The compliant suspension was designed to provide for needle motion into the cells while restraining rotations or transverse motions that could result in tearing of the cell membranes. Testing was performed using propidium iodide, a membrane impermeable dye, injected into HeLa cells. Average cell survivability was found to be 97.7%, and up to 97.9% of the surviving cells received the propidium iodide.

  11. Ratiometric Array of Conjugated Polymers-Fluorescent Protein Provides a Robust Mammalian Cell Sensor.

    PubMed

    Rana, Subinoy; Elci, S Gokhan; Mout, Rubul; Singla, Arvind K; Yazdani, Mahdieh; Bender, Markus; Bajaj, Avinash; Saha, Krishnendu; Bunz, Uwe H F; Jirik, Frank R; Rotello, Vincent M

    2016-04-06

    Supramolecular complexes of a family of positively charged conjugated polymers (CPs) and green fluorescent protein (GFP) create a fluorescence resonance energy transfer (FRET)-based ratiometric biosensor array. Selective multivalent interactions of the CPs with mammalian cell surfaces caused differential change in FRET signals, providing a fingerprint signature for each cell type. The resulting fluorescence signatures allowed the identification of 16 different cell types and discrimination between healthy, cancerous, and metastatic cells, with the same genetic background. While the CP-GFP sensor array completely differentiated between the cell types, only partial classification was achieved for the CPs alone, validating the effectiveness of the ratiometric sensor. The utility of the biosensor was further demonstrated in the detection of blinded unknown samples, where 121 of 128 samples were correctly identified. Notably, this selectivity-based sensor stratified diverse cell types in minutes, using only 2000 cells, without requiring specific biomarkers or cell labeling.

  12. Organic electrochemical transistor array for recording transepithelial ion transport of human airway epithelial cells.

    PubMed

    Yao, Chunlei; Xie, Changyan; Lin, Peng; Yan, Feng; Huang, Pingbo; Hsing, I-Ming

    2013-12-03

    An organic electrochemical transistor array is integrated with human airway epithelial cells. This integration provides a novel method to couple transepithelial ion transport with electrical current. Activation and inhibition of transepithelial ion transport are readily detected with excellent time resolution. The organic electrochemical transistor array serves as a promising platform for physiological studies and drug testing. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Recursive Trace Line Method for Detecting Myelinated Bundles: a Comparison Study with Pyramidal Cell Arrays

    PubMed Central

    Casanova, Manuel F.; Konkachbaev, Anouar I.; Switala, Andrew E.; Elmaghraby, Adel S.

    2008-01-01

    Minicolumns are thought to be the smallest cortical modules within the hierarchical organization of the isocortex. Several reports suggest alterations in minicolumnar morphometry may be involved in psychiatric disorders such as autism, dyslexia, and schizophrenia. Thus far anatomical studies of minicolumns have primarily relied on measurements of pyramidal cell arrays. This study expands on a recursive trace line segmentation method used to define morphometric measures for myelinated axon bundles. The results were compared against those of pyramidal cell arrays derived from immediately adjacent serial sections. Width estimates based on cell somas and myelinated axon bundles were highly correlated (r = 0.9888). Histograms of signal intensity using the recursive trace line method produced expected features of myeloarchitectonics; that is, bundles of Meynert and intervening interradiary plexus. The close correspondence of derived values for myelinated axon bundles and pyramidal cell arrays suggests their participation and interaction within the same modular arrangement of the isocortex. PMID:18192023

  14. Characterization of the San Jacinto Fault Zone Northwest of the Trifurcation Area from Earthquake Data Recorded by a Dense Linear Array

    NASA Astrophysics Data System (ADS)

    Share, P. E.; Ben-Zion, Y.; Ross, Z.; Qiu, H.; Vernon, F.

    2015-12-01

    Data generated by earthquakes and recorded by a linear seismic array at Blackburn saddle NW of the trifurcation area, crossing the Clark branch of the San Jacinto Fault Zone, are used to study the internal fault zone structure in the area. The linear array (BB) is 180 m long and comprises 7 broadband three-component 1-Hz seismometers. Automatic algorithms are used to detect P and S body waves and fault zone head and trapped waves. Statistical analyses of P body wave travel times of 765 events, occurring during 2012-2014 within a 110 by 20 km window centered along the length of the Clark fault, show a 0.6-0.8 % gradual increase in slowness from the SW most (BB01) to the NE most (BB07) station. The results suggest the NE most stations overlie a zone of greater damage. Sharp velocity contrasts across the fault are imaged using fault zone head waves. In total, 72 events (within the same 110 by 20 km window) are found to produce phases with clear head wave characteristics. Further analysis of the candidate events leads to the characterization of two separate groups. The first, consisting of 51 events within approximately 11 km epicentral distance from the array, shows a clear increase of head to P body wave differential times with increasing along fault distance. Based on this moveout, an average velocity contrast across of the fault of 4 % (SW block is slower) is calculated for the portion of the Clark Fault beneath the array. Differential times for the second group show no moveout with along fault distance, suggesting a local secondary bimaterial interface with limited along-strike and/or depth extent. Events located in a broad region that also includes the San Andreas and Elsinore Faults produce candidate trapped waves that are most clear at stations BB05, BB06 and BB07 (the three NE most stations). Waveform modeling results will be presented in the meeting.

  15. Plasmonic nanodot array optimization on organic thin film solar cells using anodic aluminum oxide templates

    NASA Astrophysics Data System (ADS)

    Bae, Kyuyoung; Kim, Kyoungsik

    2013-09-01

    The fabrication method of plasmonic nanodots on ITO or nc-ZnO substrate has been developed to improve the efficiency of organic thin film solar cells. Nanoscale metallic nanodots arrays are fabricated by anodic aluminum oxide (AAO) template mask which can have different structural parameters by varying anodization conditions. In this paper, the structural parameters of metallic nanodots, which can be controlled by the diverse structures of AAO template mask, are investigated to enhance the optical properties of organic thin film solar cells. It is found that optical properties of the organic thin film solar cells are improved by finding optimization values of the structural parameters of the metallic nanodot array.

  16. Light management in perovskite solar cells and organic LEDs with microlens arrays

    DOE PAGES

    Peer, Akshit; Biswas, Rana; Park, Joong -Mok; ...

    2017-04-28

    Here, we demonstrate enhanced absorption in solar cells and enhanced light emission in OLEDs by light interaction with a periodically structured microlens array. We simulate n-i-p perovskite solar cells with a microlens at the air-glass interface, with rigorous scattering matrix simulations. The microlens focuses light in nanoscale regions within the absorber layer enhancing the solar cell. Optimal period of ~700 nm and microlens height of ~800-1000 nm, provides absorption (photocurrent) enhancement of 6% (6.3%). An external polymer microlens array on the air-glass side of the OLED generates experimental and theoretical enhancements >100%, by outcoupling trapped modes in the glass substrate.

  17. Copy Number Variation Analysis by Array Analysis of Single Cells Following Whole Genome Amplification.

    PubMed

    Dimitriadou, Eftychia; Zamani Esteki, Masoud; Vermeesch, Joris Robert

    2015-01-01

    Whole genome amplification is required to ensure the availability of sufficient material for copy number variation analysis of a genome deriving from an individual cell. Here, we describe the protocols we use for copy number variation analysis of non-fixed single cells by array-based approaches following single-cell isolation and whole genome amplification. We are focusing on two alternative protocols, an isothermal and a PCR-based whole genome amplification method, followed by either comparative genome hybridization (aCGH) or SNP array analysis, respectively.

  18. Si/PEDOT:PSS core/shell nanowire arrays for efficient hybrid solar cells.

    PubMed

    Lu, Wenhui; Wang, Chengwei; Yue, Wei; Chen, Liwei

    2011-09-01

    A solution filling and drying method has been demonstrated to fabricate Si/PEDOT:PSS core/shell nanowire arrays for hybrid solar cells. The hybrid core/shell nanowire arrays show excellent broadband anti-reflection, and resulting hybrid solar cells absorb about 88% of AM 1.5G photons in the 300-1100 nm range. The power conversion efficiency (PCE) of the hybrid solar cell reaches 6.35%, and is primarily limited by direct and indirect interfacial recombination of charge carriers.

  19. Tissue matrix arrays for high-throughput screening and systems analysis of cell function.

    PubMed

    Beachley, Vince Z; Wolf, Matthew T; Sadtler, Kaitlyn; Manda, Srikanth S; Jacobs, Heather; Blatchley, Michael R; Bader, Joel S; Pandey, Akhilesh; Pardoll, Drew; Elisseeff, Jennifer H

    2015-12-01

    Cell and protein arrays have demonstrated remarkable utility in the high-throughput evaluation of biological responses; however, they lack the complexity of native tissue and organs. Here we spotted tissue extracellular matrix (ECM) particles as two-dimensional (2D) arrays or incorporated them with cells to generate three-dimensional (3D) cell-matrix microtissue arrays. We then investigated the responses of human stem, cancer and immune cells to tissue ECM arrays originating from 11 different tissues. We validated the 2D and 3D arrays as representative of the in vivo microenvironment by means of quantitative analysis of tissue-specific cellular responses, including matrix production, adhesion and proliferation, and morphological changes after culture. The biological outputs correlated with tissue proteomics, and network analysis identified several proteins linked to cell function. Our methodology enables broad screening of ECMs to connect tissue-specific composition with biological activity, providing a new resource for biomaterials research and further understanding of regeneration and disease mechanisms.

  20. Array tomography: characterizing FAC-sorted populations of zebrafish immune cells by their 3D ultrastructure

    PubMed Central

    Wacker, Irene; Chockley, Peter; Bartels, Carolin; Spomer, Waldemar; Hofmann, Andreas; Gengenbach, Ulrich; Singh, Sachin; Thaler, Marlene; Grabher, Clemens; SCHRÖDER, RASMUS R

    2015-01-01

    For 3D reconstructions of whole immune cells from zebrafish, isolated from adult animals by FAC-sorting we employed array tomography on hundreds of serial sections deposited on silicon wafers. Image stacks were either recorded manually or automatically with the newly released ZEISS Atlas 5 Array Tomography platform on a Zeiss FEGSEM. To characterize different populations of immune cells, organelle inventories were created by segmenting individual cells. In addition, arrays were used for quantification of cell populations with respect to the various cell types they contained. The detection of immunological synapses in cocultures of cell populations from thymus or WKM with cancer cells helped to identify the cytotoxic nature of these cells. Our results demonstrate the practicality and benefit of AT for high-throughput ultrastructural imaging of substantial volumes. Lay Description To look at immune cells from zebrafish we employed array tomography, a technique where arrays of serial sections deposited on solid substrates are used for imaging. Cell populations were isolated from the different organs of zebrafish involved in haematopoiesis, the production of blood cells. They were chemically fixed and centrifuged to concentrate them in a pellet that was then dehydrated and embedded in resin. Using a custom-built handling device it was possible to place hundreds of serial sections on silicon wafers as well ordered arrays. To image a whole cell at a resolution that would allow identifying all the organelles (i.e. compartments surrounded by membranes) inside the cell, stacks of usually 50–100 images were recorded in a scanning electron microscope (SEM). This recording was either done manually or automatically using the newly released Atlas Array Tomography platform on a ZEISS SEM. For the imaging of the sections a pixel size of about 5 nm was chosen, which defines membrane boundaries very well and allows segmentation of the membrane topology. After alignment of the

  1. A planar interdigitated ring electrode array via dielectrophoresis for uniform patterning of cells.

    PubMed

    Hsiung, Lo-Chang; Yang, Chun-Hui; Chiu, Chi-Li; Chen, Chen-Lin; Wang, Yueh; Lee, Hsinyu; Cheng, Ji-Yen; Ho, Ming-Chih; Wo, Andrew M

    2008-12-01

    Uniform patterning of cells is highly desirable for most cellular studies involving cell-cell interactions but is often difficult in an in vitro environment. This paper presents the development of a collagen-coated planar interdigitated ring electrode (PIRE) array utilizing positive dielectrophoresis to pattern cells uniformly. Key features of the PIRE design include: (1) maximizing length along the edges where the localized maximum in the electric field exists; (2) making the inner gap slightly smaller than the outer gap in causing the electric field strength near the center of a PIRE being generally stronger than that near the outer edge of the same PIRE. Results of human hepatocellular carcinoma cells, HepG2, adhered on a 6x6 PIRE array show that cells patterned within minutes with good uniformity (48+/-6 cells per PIRE). Cell viability test revealed healthy patterned cells after 24h that were still confined to the collagen-coated PIREs. Furthermore, quantification of fluorescence intensity of living cells shows an acceptable reproducibility of cell viability among PIREs (mean normalized intensity per PIRE was 1+/-0.138). The results suggest that the PIRE array would benefit applications that desire uniform cellular patterning, and improve both response and reproducibility of cell-based biosensors.

  2. A linear photodiode array employed in a short range laser triangulation obstacle avoidance sensor. M.S. Thesis; [Martian roving vehicle sensor

    NASA Technical Reports Server (NTRS)

    Odenthal, J. P.

    1980-01-01

    An opto-electronic receiver incorporating a multi-element linear photodiode array as a component of a laser-triangulation rangefinder was developed as an obstacle avoidance sensor for a Martian roving vehicle. The detector can resolve the angle of laser return in 1.5 deg increments within a field of view of 30 deg and a range of five meters. A second receiver with a 1024 elements over 60 deg and a 3 meter range is also documented. Design criteria, circuit operation, schematics, experimental results and calibration procedures are discussed.

  3. Masking mechanisms applied to thin-film coatings for the manufacturing of linear variable filters for two-dimensional array detectors.

    PubMed

    Abel-Tibérini, Laëtitia; Lemarquis, Frédéric; Lequime, Michel

    2008-10-20

    We propose a method for manufacturing linear variable interference filters for two-dimensional (2D) array detectors, based on the use of correcting masks combining both rotation and translation movements of the masks and substrates. The major advantage of this method is its capability to produce several identical filters in a single run. 20 mm x 20 mm samples were manufactured with a wavelength ratio almost equal to 2 along the thickness gradient direction. In agreement with calculations, the measured uniformity perpendicular to the gradient is about 99.8% along 20 mm.

  4. Collision rates for rare cell capture in periodic obstacle arrays strongly depend on density of cell suspension.

    PubMed

    Cimrák, I

    2016-11-01

    Recently, computational modelling has been successfully used for determination of collision rates for rare cell capture in periodic obstacle arrays. The models were based on particle advection simulations where the cells were advected according to velocity field computed from two dimensional Navier-Stokes equations. This approach may be used under the assumption of very dilute cell suspensions where no mutual cell collisions occur. We use the object-in-fluid framework to demonstrate that even with low cell-to-fluid ratio, the optimal geometry of the obstacle array significantly changes. We show computational simulations for ratios of 3.5, 6.9 and 10.4% determining the optimal geometry of the periodic obstacle arrays. It was already previously demonstrated that cells in periodic obstacle arrays follow trajectories in two modes: the colliding mode and the zig-zag mode. The colliding mode maximizes the cell-obstacle collision frequency. Our simulations reveal that for dilute suspensions and for suspensions with cell-to-fluid ratio 3.5%, there is a range of column shifts for which the cells follow colliding trajectories. However we showed, that for 6.9 and 10.4%, the cells never follow colliding trajectories.

  5. Linear fitting of multi-threshold counting data with a pixel-array detector for spectral X-ray imaging

    PubMed Central

    Muir, Ryan D.; Pogranichney, Nicholas R.; Muir, J. Lewis; Sullivan, Shane Z.; Battaile, Kevin P.; Mulichak, Anne M.; Toth, Scott J.; Keefe, Lisa J.; Simpson, Garth J.

    2014-01-01

    Experiments and modeling are described to perform spectral fitting of multi-threshold counting measurements on a pixel-array detector. An analytical model was developed for describing the probability density function of detected voltage in X-ray photon-counting arrays, utilizing fractional photon counting to account for edge/corner effects from voltage plumes that spread across multiple pixels. Each pixel was mathematically calibrated by fitting the detected voltage distributions to the model at both 13.5 keV and 15.0 keV X-ray energies. The model and established pixel responses were then exploited to statistically recover images of X-ray intensity as a function of X-ray energy in a simulated multi-wavelength and multi-counting threshold experiment. PMID:25178010

  6. Linear fitting of multi-threshold counting data with a pixel-array detector for spectral X-ray imaging.

    PubMed

    Muir, Ryan D; Pogranichney, Nicholas R; Muir, J Lewis; Sullivan, Shane Z; Battaile, Kevin P; Mulichak, Anne M; Toth, Scott J; Keefe, Lisa J; Simpson, Garth J

    2014-09-01

    Experiments and modeling are described to perform spectral fitting of multi-threshold counting measurements on a pixel-array detector. An analytical model was developed for describing the probability density function of detected voltage in X-ray photon-counting arrays, utilizing fractional photon counting to account for edge/corner effects from voltage plumes that spread across multiple pixels. Each pixel was mathematically calibrated by fitting the detected voltage distributions to the model at both 13.5 keV and 15.0 keV X-ray energies. The model and established pixel responses were then exploited to statistically recover images of X-ray intensity as a function of X-ray energy in a simulated multi-wavelength and multi-counting threshold experiment.

  7. Microscale Bioadhesive Hydrogel Arrays for Cell Engineering Applications.

    PubMed

    Patel, Ravi Ghanshyam; Purwada, Alberto; Cerchietti, Leandro; Inghirami, Giorgio; Melnick, Ari; Gaharwar, Akhilesh K; Singh, Ankur

    2014-09-01

    Bioengineered hydrogels have been explored in cell and tissue engineering applications to support cell growth and modulate its behavior. A rationally designed scaffold should allow for encapsulated cells to survive, adhere, proliferate, remodel the niche, and can be used for controlled delivery of biomolecules. Here we report a microarray of composite bioadhesive microgels with modular dimensions, tunable mechanical properties and bulk modified adhesive biomolecule composition. Composite bioadhesive microgels of maleimide functionalized polyethylene glycol (PEG-MAL) with interpenetrating network (IPN) of gelatin ionically cross-linked with silicate nanoparticles were engineered by integrating microfabrication with Michael-type addition chemistry and ionic gelation. By encapsulating clinically relevant anchorage-dependent cervical cancer cells and suspension leukemia cells as cell culture models in these composite microgels, we demonstrate enhanced cell spreading, survival, and metabolic activity compared to control gels. The composite bioadhesive hydrogels represent a platform that could be used to study independent effect of stiffness and adhesive ligand density on cell survival and function. We envision that such microarrays of cell adhesive microenvironments, which do not require harsh chemical and UV crosslinking conditions, will provide a more efficacious cell culture platform that can be used to study cell behavior and survival, function as building blocks to fabricate 3D tissue structures, cell delivery systems, and high throughput drug screening devices.

  8. Insertion of linear 8.4 μm diameter 16 channel carbon fiber electrode arrays for single unit recordings.

    PubMed

    Patel, Paras R; Na, Kyounghwan; Zhang, Huanan; Kozai, Takashi D Y; Kotov, Nicholas A; Yoon, Euisik; Chestek, Cynthia A

    2015-08-01

    Single carbon fiber electrodes (d = 8.4 μm) insulated with parylene-c and functionalized with pTS have been shown to record single unit activity but manual implantation of these devices with forceps can be difficult. Without an improvement in the insertion method any increase in the channel count by fabricating carbon fiber arrays would be impractical. In this study, we utilize a water soluble coating and structural backbones that allow us to create, implant, and record from fully functionalized arrays of carbon fibers with ∼150 μm pitch. Two approaches were tested for the insertion of carbon fiber arrays. The first method used a poly(ethylene glycol) (PEG) coating that temporarily stiffened the fibers while leaving a small portion at the tip exposed. The small exposed portion (500 μm-1 mm) readily penetrated the brain allowing for an insertion that did not require the handling of each fiber by forceps. The second method involved the fabrication of silicon support structures with individual shanks spaced 150 μm apart. Each shank consisted of a small groove that held an individual carbon fiber. Our results showed that the PEG coating allowed for the chronic implantation of carbon fiber arrays in five rats with unit activity detected at 31 days post-implant. The silicon support structures recorded single unit activity in three acute rat surgeries. In one of those surgeries a stacked device with three layers of silicon support structures and carbon fibers was built and shown to readily insert into the brain with unit activity on select sites. From these studies we have found that carbon fibers spaced at ∼150 μm readily insert into the brain. This greatly increases the recording density of chronic neural probes and paves the way for even higher density devices that have a minimal scarring response.

  9. Insertion of linear 8.4 μm diameter 16 channel carbon fiber electrode arrays for single unit recordings

    PubMed Central

    Patel, Paras R.; Na, Kyounghwan; Zhang, Huanan; Kozai, Takashi D. Y.; Kotov, Nicholas A.; Yoon, Euisik; Chestek, Cynthia A.

    2016-01-01

    Objective Single carbon fiber electrodes (d=8.4 μm) insulated with parylene-c and functionalized with PEDOT:pTS have been shown to record single unit activity but manual implantation of these devices with forceps can be difficult. Without an improvement in the insertion method any increase in the channel count by fabricating carbon fiber arrays would be impractical. In this study, we utilize a water soluble coating and structural backbones that allow us to create, implant, and record from fully functionalized arrays of carbon fibers with ~150 μm pitch. Approach Two approaches were tested for the insertion of carbon fiber arrays. The first method used a PEG coating that temporarily stiffened the fibers while leaving a small portion at the tip exposed. The small exposed portion (500 μm – 1 mm) readily penetrated the brain allowing for an insertion that did not require the handling of each fiber by forceps. The second method involved the fabrication of silicon support structures with individual shanks spaced 150 μm apart. Each shank consisted of a small groove that held an individual carbon fiber. Main results Our results showed that the PEG coating allowed for the chronic implantation of carbon fiber arrays in 5 rats with unit activity detected at 31 days post-implant. The silicon support structures recorded single unit activity in 3 acute rat surgeries. In one of those surgeries a stacked device with 3 layers of silicon support structures and carbon fibers was built and shown to readily insert into the brain with unit activity on select sites. Significance From these studies we have found that carbon fibers spaced at ~150 μm readily insert into the brain. This greatly increases the recording density of chronic neural probes and paves the way for even higher density devices that have a minimal scarring response. PMID:26035638

  10. Insertion of linear 8.4 μm diameter 16 channel carbon fiber electrode arrays for single unit recordings

    NASA Astrophysics Data System (ADS)

    Patel, Paras R.; Na, Kyounghwan; Zhang, Huanan; Kozai, Takashi D. Y.; Kotov, Nicholas A.; Yoon, Euisik; Chestek, Cynthia A.

    2015-08-01

    Objective. Single carbon fiber electrodes (d = 8.4 μm) insulated with parylene-c and functionalized with PEDOT:pTS have been shown to record single unit activity but manual implantation of these devices with forceps can be difficult. Without an improvement in the insertion method any increase in the channel count by fabricating carbon fiber arrays would be impractical. In this study, we utilize a water soluble coating and structural backbones that allow us to create, implant, and record from fully functionalized arrays of carbon fibers with ˜150 μm pitch. Approach. Two approaches were tested for the insertion of carbon fiber arrays. The first method used a poly(ethylene glycol) (PEG) coating that temporarily stiffened the fibers while leaving a small portion at the tip exposed. The small exposed portion (500 μm-1 mm) readily penetrated the brain allowing for an insertion that did not require the handling of each fiber by forceps. The second method involved the fabrication of silicon support structures with individual shanks spaced 150 μm apart. Each shank consisted of a small groove that held an individual carbon fiber. Main results. Our results showed that the PEG coating allowed for the chronic implantation of carbon fiber arrays in five rats with unit activity detected at 31 days post-implant. The silicon support structures recorded single unit activity in three acute rat surgeries. In one of those surgeries a stacked device with three layers of silicon support structures and carbon fibers was built and shown to readily insert into the brain with unit activity on select sites. Significance. From these studies we have found that carbon fibers spaced at ˜150 μm readily insert into the brain. This greatly increases the recording density of chronic neural probes and paves the way for even higher density devices that have a minimal scarring response.

  11. Salvage of fetal karyotype information from SNP array data obtained from products of conception with maternal cell contamination.

    PubMed

    Sasaki, Karin; Abe, Kosei; Mori, Takahide; Hashimoto, Kazunori; Nakabayashi, Kazuhiko

    2017-08-01

    Maternal cell contamination (MCC) is known to increase the risk of misdiagnosis in prenatal diagnosis as well as in diagnostic tests for the products of conception (POC) from miscarriages. We aimed to develop a data correction method to salvage fetal karyotype information from single-nucleotide polymorphism (SNP) array data for POC with MCC when parental genotype data are available. We obtained SNP array data from mixed genomic DNAs of a mother-child pair and used the dataset to assess the accuracy of data correction. We subsequently applied our method to miscarriage specimens with MCC. We adopted a linear interpolation model as a data correction method and implemented the method in an R package, snpsal. We successfully determined the fetal karyotypes of two miscarriage specimens that were previously undiagnosed due to MCC to be normal in one case and trisomy 16 in the other case using snpsal. The R package, snpsal, developed in this study facilitates rapid and accurate estimation of the fetal karyotype from SNP array data for POC with MCC. © 2017 John Wiley & Sons, Ltd. © 2017 John Wiley & Sons, Ltd.

  12. Arrayed three-dimensional structures designed to induce and maintain a cell pattern by a topographical effect on cell behavior.

    PubMed

    Saito, Takao; Teraoka, Kay; Ota, Kazuyoshi

    2015-04-01

    We investigated the ability of the microscale topography of a three-dimensional (3-D) structure arrayed on the surface of a substrate to induce and maintain a cell pattern by controlling cell behavior. Arrayed 3-D structures having different topographical characteristics, i.e., geometry and dimension, were fabricated on the surface of glass substrates by masked sand blasting. Each 3-D structure was designed to have a unit composed of a planar island for cell growth and surrounding grooves exhibiting cell repellency. The principle of the cell repellency is based on the topographical control of cell attachment, spreading, growth, and differentiation by utilizing the spatially restricted microenvironment of the grooves. Grooves with a width of less than approximately 116μm and a depth of approximately 108μm formed narrow V-shapes with a dihedral angle of less than approximately 44.4°. Cell culture experiments using osteoblast-like cells demonstrated that these narrow V-shaped grooves had sufficient cell repellency to form and maintain a cell pattern on the surface for at least 14days. From the present study, arrayed 3-D structures designed to have narrow V-shaped grooves with optimal topographical characteristics for cell repellency are promising for the formation of stable cell patterns for creating novel cell microarray platforms without using conventional protein/cell-repellent chemicals.

  13. Oligonucleotide Arrays vs. Metaphase-Comparative Genomic Hybridisation and BAC Arrays for Single-Cell Analysis: First Applications to Preimplantation Genetic Diagnosis for Robertsonian Translocation Carriers

    PubMed Central

    Ramos, Laia; del Rey, Javier; Daina, Gemma; García-Aragonés, Manel; Armengol, Lluís; Fernandez-Encinas, Alba; Parriego, Mònica; Boada, Montserrat; Martinez-Passarell, Olga; Martorell, Maria Rosa; Casagran, Oriol; Benet, Jordi; Navarro, Joaquima

    2014-01-01

    Comprehensive chromosome analysis techniques such as metaphase-Comparative Genomic Hybridisation (CGH) and array-CGH are available for single-cell analysis. However, while metaphase-CGH and BAC array-CGH have been widely used for Preimplantation Genetic Diagnosis, oligonucleotide array-CGH has not been used in an extensive way. A comparison between oligonucleotide array-CGH and metaphase-CGH has been performed analysing 15 single fibroblasts from aneuploid cell-lines and 18 single blastomeres from human cleavage-stage embryos. Afterwards, oligonucleotide array-CGH and BAC array-CGH were also compared analysing 16 single blastomeres from human cleavage-stage embryos. All three comprehensive analysis techniques provided broadly similar cytogenetic profiles; however, non-identical profiles appeared when extensive aneuploidies were present in a cell. Both array techniques provided an optimised analysis procedure and a higher resolution than metaphase-CGH. Moreover, oligonucleotide array-CGH was able to define extra segmental imbalances in 14.7% of the blastomeres and it better determined the specific unbalanced chromosome regions due to a higher resolution of the technique (≈20 kb). Applicability of oligonucleotide array-CGH for Preimplantation Genetic Diagnosis has been demonstrated in two cases of Robertsonian translocation carriers 45,XY,der(13;14)(q10;q10). Transfer of euploid embryos was performed in both cases and pregnancy was achieved by one of the couples. This is the first time that an oligonucleotide array-CGH approach has been successfully applied to Preimplantation Genetic Diagnosis for balanced chromosome rearrangement carriers. PMID:25415307

  14. Oligonucleotide arrays vs. metaphase-comparative genomic hybridisation and BAC arrays for single-cell analysis: first applications to preimplantation genetic diagnosis for Robertsonian translocation carriers.

    PubMed

    Ramos, Laia; del Rey, Javier; Daina, Gemma; García-Aragonés, Manel; Armengol, Lluís; Fernandez-Encinas, Alba; Parriego, Mònica; Boada, Montserrat; Martinez-Passarell, Olga; Martorell, Maria Rosa; Casagran, Oriol; Benet, Jordi; Navarro, Joaquima

    2014-01-01

    Comprehensive chromosome analysis techniques such as metaphase-Comparative Genomic Hybridisation (CGH) and array-CGH are available for single-cell analysis. However, while metaphase-CGH and BAC array-CGH have been widely used for Preimplantation Genetic Diagnosis, oligonucleotide array-CGH has not been used in an extensive way. A comparison between oligonucleotide array-CGH and metaphase-CGH has been performed analysing 15 single fibroblasts from aneuploid cell-lines and 18 single blastomeres from human cleavage-stage embryos. Afterwards, oligonucleotide array-CGH and BAC array-CGH were also compared analysing 16 single blastomeres from human cleavage-stage embryos. All three comprehensive analysis techniques provided broadly similar cytogenetic profiles; however, non-identical profiles appeared when extensive aneuploidies were present in a cell. Both array techniques provided an optimised analysis procedure and a higher resolution than metaphase-CGH. Moreover, oligonucleotide array-CGH was able to define extra segmental imbalances in 14.7% of the blastomeres and it better determined the specific unbalanced chromosome regions due to a higher resolution of the technique (≈ 20 kb). Applicability of oligonucleotide array-CGH for Preimplantation Genetic Diagnosis has been demonstrated in two cases of Robertsonian translocation carriers 45,XY,der(13;14)(q10;q10). Transfer of euploid embryos was performed in both cases and pregnancy was achieved by one of the couples. This is the first time that an oligonucleotide array-CGH approach has been successfully applied to Preimplantation Genetic Diagnosis for balanced chromosome rearrangement carriers.

  15. Application of a Halbach magnetic array for long-range cell and particle separations in biological samples

    NASA Astrophysics Data System (ADS)

    Kang, Joo H.; Driscoll, Harry; Super, Michael; Ingber, Donald E.

    2016-05-01

    Here, we describe a versatile application of a planar Halbach permanent magnet array for an efficient long-range magnetic separation of living cells and microparticles over distances up to 30 mm. A Halbach array was constructed from rectangular bar magnets using 3D-printed holders and compared to a conventional alternating array of identical magnets. We theoretically predicted the superiority of the Halbach array for a long-range magnetic separation and then experimentally validated that the Halbach configuration outperforms the alternating array for isolating magnetic microparticles or microparticle-bound bacterial cells at longer distances. Magnetophoretic velocities (ymag) of magnetic particles (7.9 μm diameter) induced by the Halbach array in a microfluidic device were significantly higher and extended over a larger area than those induced by the alternating magnet array (ymag = 178 versus 0 μm/s at 10 mm, respectively). When applied to 50 ml tubes (˜30 mm diameter), the Halbach array removed >95% of Staphylococcus aureus bacterial cells bound with 1 μm magnetic particles compared to ˜70% removed using the alternating array. In addition, the Halbach array enabled manipulation of 1 μm magnetic beads in a deep 96-well plate for ELISA applications, which was not possible with the conventional magnet arrays. Our analysis demonstrates the utility of the Halbach array for the future design of devices for high-throughput magnetic separations of cells, molecules, and toxins.

  16. Microbubble Array Diffusion Assay for the Detection of Cell Secreting Factors

    PubMed Central

    Bobo, Bryan; Phalen, Dana; Rebhahn, Jonathan; Piepenbrink, Michael S.; Zheng, Bo; Mosmann, Tim R.; Kobie, James J.; DeLouise, Lisa

    2014-01-01

    The therapeutic potential of monoclonal antibodies (mAbs) makes them an ideal tool in both clinical and research applications due to their ability to recognize and bind specific epitopes with high affinity and selectivity. While mAbs offer significant therapeutic potential, their utility is overshadowed by the cost associated with their production, which often relies on the ability to identify minority antigen specific cells out of a heterogeneous population. To address concerns with suboptimal methods for screening cells, we have developed a cell sorting array comprised of nanoliter spherical cell culture compartments, termed microbubble (MB) wells. We demonstrate a proof-of-concept system for the detection of cell secreted factors from both immortalized cell lines and primary B cell samples. Exploiting the unique ability of the MB well architecture to accumulate cell secreted factors as well as affinity capture coatings, we demonstrate on chip detection and recovery of antibody secreting cells for sequencing of immunoglobin genes. Furthermore, rapid image capture and analysis capabilities were developed for the processing of large MB arrays, thus facilitating the ability to conduct high-throughput screening of heterogeneous cell samples faster and more efficiently than ever before. The proof-of-concept assays presented herein lay the groundwork for the progression of MB well arrays as an advanced on chip cell sorting technology. PMID:25079889

  17. A microchip integrating cell array positioning with in situ single-cell impedance measurement.

    PubMed

    Guo, Xiaoliang; Zhu, Rong; Zong, Xianli

    2015-10-07

    This paper presents a novel microarray chip integrating cell positioning with in situ, real-time and long-time impedance measurement on a single cell. The microchip integrates a plurality of quadrupole-electrode units (termed positioning electrodes) patterned into an array with pairs of planar electrodes (termed measuring electrodes) located at the centers of each quadrupole-electrode unit. The positioning electrodes are utilized to trap and position living cells onto the measuring electrodes based on negative dielectrophoresis (nDEP), while the measuring electrodes are used to measure impedances of the trapped single cells. Each measuring electrode has a small footprint area of 7 × 7 μm(2) to ensure inhabiting only one single cell on it. However, the electrode with a small surface area has a low double-layer capacitance when it is immersed in a liquid solution, thus generating a large double-layer impedance, which reduces the sensitivity for impedance measurement on the single cell. To enlarge the effective surface areas of the measuring electrodes, a novel surface-modification process is proposed to controllably construct gold nanostructures on the surfaces of the measuring electrodes while the positioning electrodes are unstained. The double layer capacitances of the modified electrodes are increased by about one order after surface-modification. The developed microchip is used to monitor the adhering behavior of a single HeLa cell by measuring its impedance spectra in real time. The measured impedance is analyzed and used to extract cellular electrical parameters, which demonstrated that the cell compresses the electrical double layer in the process of adherence and adheres onto the measuring electrodes after 4-5 hours.

  18. Non-linear patterns in age-related DNA methylation may reflect CD4(+) T cell differentiation.

    PubMed

    Johnson, Nicholas D; Wiener, Howard W; Smith, Alicia K; Nishitani, Shota; Absher, Devin M; Arnett, Donna K; Aslibekyan, Stella; Conneely, Karen N

    2017-04-07

    DNA methylation (DNAm) is an important epigenetic process involved in the regulation of gene expression. While many studies have identified thousands of loci associated with age, few have differentiated between linear and non-linear DNAm trends with age. Non-linear trends could indicate early- or late-life gene regulatory processes. Using data from the Illumina 450K array on 336 human peripheral blood samples, we identified 21 CpG sites that associated with age (P<1.03E-7) and exhibited changing rates of DNAm change with age (P<1.94E-6). For two of these CpG sites (cg07955995 and cg22285878), DNAm increased with age at an increasing rate, indicating that differential DNAm was greatest among elderly individuals. We observed significant replication for both CpG sites (P<5.0E-8) in a second set of peripheral blood samples. In 8 of 9 additional datasets comprising samples of monocytes, T cell subtypes, and brain tissue, we observed a pattern directionally consistent with DNAm increasing with age at an increasing rate, which was nominally significant in the three largest datasets (4.3E-15cell differentiation via the repression of FOXP3. These findings may suggest a possible role for cg07955995 and cg22285878 in immunosenescence.

  19. Solar Cell and Array Technology Development for NASA Solar Electric Propulsion Missions

    NASA Technical Reports Server (NTRS)

    Piszczor, Michael; McNatt, Jeremiah; Mercer, Carolyn; Kerslake, Tom; Pappa, Richard

    2012-01-01

    NASA is currently developing advanced solar cell and solar array technologies to support future exploration activities. These advanced photovoltaic technology development efforts are needed to enable very large (multi-hundred kilowatt) power systems that must be compatible with solar electric propulsion (SEP) missions. The technology being developed must address a wide variety of requirements and cover the necessary advances in solar cell, blanket integration, and large solar array structures that are needed for this class of missions. Th is paper will summarize NASA's plans for high power SEP missions, initi al mission studies and power system requirements, plans for advanced photovoltaic technology development, and the status of specific cell and array technology development and testing that have already been conducted.

  20. Stress Analysis and Design of Silicon Solar Cell Arrays and Related Material Properties

    NASA Technical Reports Server (NTRS)

    Salama, A. M.; Rowe, W. M.; Yasui, R. K.

    1972-01-01

    A systematic approach is presented for the design of solar cell arrays to eliminate mechanical failures that might arise in components of the arrays in a thermal environment. A prerequisite to the approach is the characterization of material properties at different temperatures. Significant data is obtained for the thermal behavior of the silicon solar cell material and adhesives. Upon determining the mechanical and thermal material properties of the components of the solar cell array, utilizing a finite element idealization for predicting the stress fields in the components, and employing the von Mises failure criterion, potential failure areas in various design configurations in a given thermal environment are identified. Guide lines and means to optimize a given design are illustrated by two examples.