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Sample records for monolithic crystal pet

  1. Monolithic crystals for PET devices: Optical coupling optimization

    Energy Technology Data Exchange (ETDEWEB)

    González, A.J., E-mail: agonzalez@i3m.upv.es; Peiró, A.; Conde, P.; Hernández, L.; Moliner, L.; Orero, A.; Rodríguez-Álvarez, M.J.; Sánchez, F.; Soriano, A.; Vidal, L.F.; Benlloch, J.M.

    2013-12-11

    In this work we present a method to efficiently collect scintillation light when using monolithic scintillator crystals. The acceptance angle of the scintillation light has been reduced by means of optical devices reducing the border effect which typically affects continuous crystals. We have applied this procedure on gamma detectors for PET systems using both position sensitive PMTs and arrays of SiPMs. In the case of using SiPMs, this approach also helps to reduce the photosensor active area. We evaluated the method using PMTs with a variety of different crystals with thicknesses ranging from 10 to 24 mm. We found that our design allows the use of crystal blocks with a thickness of up to 18 mm without degrading the spatial resolution caused by edge effects and without a significant detriment to the energy resolution. These results were compared with simulated data. The first results of monolithic LYSO crystals coupled to an array of 256 SiPMs by means of individual optical light guides are also presented. -- Highlights: •Acceptance angle reduction decreases border effect in continuous crystals. •Experimental measurements with PMTs correlate well with simulated data. •Optical devices called faceplates serve to control the scintillation light angle. •Simulation on the light propagation for SiPMs requires exhaustive modeling.

  2. A High Resolution Monolithic Crystal, DOI, MR Compatible, PET Detector

    Energy Technology Data Exchange (ETDEWEB)

    Robert S Miyaoka

    2012-03-06

    The principle objective of this proposal is to develop a positron emission tomography (PET) detector with depth-of-interaction (DOI) positioning capability that will achieve state of the art spatial resolution and sensitivity performance for small animal PET imaging. When arranged in a ring or box detector geometry, the proposed detector module will support <1 mm3 image resolution and >15% absolute detection efficiency. The detector will also be compatible with operation in a MR scanner to support simultaneous multi-modality imaging. The detector design will utilize a thick, monolithic crystal scintillator readout by a two-dimensional array of silicon photomultiplier (SiPM) devices using a novel sensor on the entrance surface (SES) design. Our hypothesis is that our single-ended readout SES design will provide an effective DOI positioning performance equivalent to more expensive dual-ended readout techniques and at a significantly lower cost. Our monolithic crystal design will also lead to a significantly lower cost system. It is our goal to design a detector with state of the art performance but at a price point that is affordable so the technology can be disseminated to many laboratories. A second hypothesis is that using SiPM arrays, the detector will be able to operate in a MR scanner without any degradation in performance to support simultaneous PET/MR imaging. Having a co-registered MR image will assist in radiotracer localization and may also be used for partial volume corrections to improve radiotracer uptake quantitation. The far reaching goal of this research is to develop technology for medical research that will lead to improvements in human health care.

  3. Thick monolithic scintillation crystals for TOF-PET with depth-of-interaction measurement

    NARCIS (Netherlands)

    Vinke, Ruud; van Dam, Herman T.; Seifert, Stefan; Beekman, Freek J.; Lohner, Herbert; Schaart, Dennis R.; Dendooven, Peter

    2010-01-01

    Positron emission tomography (PET) detectors based on monolithic scintillation crystals show excellent intrinsic spatial resolution and allow depth-of-interaction (DOI) reconstruction using a single photosensor array. The inclusion of time-of-flight (TOF) information in the image reconstruction

  4. Pilot tests of a PET detector using the TOF-PET ASIC based on monolithic crystals and SiPMs

    Science.gov (United States)

    Aguilar, A.; González-Montoro, A.; González, A. J.; Hernández, L.; Monzó, J. M.; Bugalho, R.; Ferramacho, L.; Benlloch, J. M.

    2016-12-01

    In this work we show pilot tests of PET detector blocks using the TOF-PET ASIC, coupled to SiPM detector arrays and different crystal configurations. We have characterized the main ASIC features running calibration processes to compensate the time dispersion among the different ASIC/SiPM paths as well as for the time walk on the arrival of optical photons. The aim of this work is to use of LYSO monolithic crystals and explore their photon Depth of Interaction (DOI) capabilities, keeping good energy and spatial resolutions. First tests have been carried out with crystal arrays. Here we made it possible to reach a coincidence resolving times (CRT) of 370 ps FWHM, with energy resolutions better than 20% and resolving well 2 mm sized crystal elements. When using monolithic crystals, a single-pixel LYSO reference crystal helped to explore the CRT performance. We studied different strategies to provide the best timestamp determination in the monolithic scintillator. Times around 1 ns FWHM have been achieved in these pilot studies. In terms of spatial and energy resolution, values of about 3 mm and better than 30% were found, respectively. We have also demonstrated the capability of this system (monolithic and ASIC) to return accurate DOI information.

  5. 3D position determination in monolithic crystals coupled to SiPMs for PET.

    Science.gov (United States)

    Etxebeste, Ane; Barrio, John; Muñoz, Enrique; Oliver, Josep F; Solaz, Carles; Llosá, Gabriela

    2016-05-21

    The interest in using continuous monolithic crystals in positron emission tomography (PET) has grown in the last years. Coupled to silicon photomultipliers (SiPMs), the detector can combine high sensitivity and high resolution, the two main factors to be maximized in a positron emission tomograph. In this work, the position determination capability of a detector comprised of a [Formula: see text] mm(3) LYSO crystal coupled to an [Formula: see text]-pixel array of SiPMs is evaluated. The 3D interaction position of γ-rays is estimated using an analytical model of the light distribution including reflections on the facets of the crystal. Monte Carlo simulations have been performed to evaluate different crystal reflectors and geometries. The method has been characterized and applied to different cases. Intrinsic resolution obtained with the position estimation method used in this work, applied to experimental data, achieves sub-millimetre resolution values. Average resolution over the detector surface for 5 mm thick crystal is  ∼0.9 mm FWHM and  ∼1.2 mm FWHM for 10 mm thick crystal. Depth of interaction resolution is close to 2 mm FWHM in both cases, while the FWTM is  ∼5.3 mm for 5 mm thick crystal and  ∼9.6 mm for 10 mm thick crystal.

  6. A high resolution, monolithic crystal, PET/MRI detector with DOI positioning capability.

    Science.gov (United States)

    Li, Xiaoli; Lockhart, Cate; Lewellen, Tom K; Miyaoka, Robert S

    2008-01-01

    We report on a high resolution, monolithic crystal PET detector design that provides depth of interaction (DOI) positioning within the crystal and is compatible for operation in a MRI scanner to support multimodal anatomic and functional imaging. Our design utilizes a novel sensor on the entrance surface (SES) design combined with a maximum likelihood positioning algorithm. The sensor will be a two-dimensional array of micro-pixel avalanche photodiodes (MAPD). MAPDs are a new type of solid-state photodetector with Geiger mode operation that can provide signal gain similar to a photomltipiler tube (PMT). In addition, they can be operated in high magnetic fields to support PET/MR imaging. Utilizing a multi-step simulation process, we determined the intrinsic spatial resolution characteristics of a detector using the proposed design. For a 48.8 mm by 48.8 mm by 15 mm LSO crystal detector readout by an 8 by 8 array of 5.8 mm by 5.8 mm MAPD elements the intrinsic spatial resolution is 0.83 mm FWHM in X, 0.92 mm FWHM in Y and 1.83 mm FWHM in Z (i.e., DOI) for normally incident photons. Comparing the results versus using a conventional design with the photosensors on the backside of the crystal, an average improvement of 25% in X, 23% in Y, and 20% in Z is achieved.

  7. Design of a High Resolution, Monolithic Crystal, PET/MRI Detector with DOI Positioning Capability.

    Science.gov (United States)

    Miyaoka, Robert S; Li, Xiaoli; Lockhart, Cate; Lewellen, Tom K

    2008-10-01

    We report on a high resolution, monolithic crystal PET detector design concept that provides depth of interaction (DOI) positioning within the crystal and is compatible for operation in a MRI scanner to support multimodal anatomic and functional imaging. Our design utilizes a novel sensor on the entrance surface (SES) approach combined with a maximum likelihood positioning algorithm. The sensor will be a two-dimensional array of micro-pixel avalanche photodiodes (MAPD). MAPDs are a new type of solid-state photodetector with Geiger mode operation that can provide signal gain similar to a photomltipiler tube (PMT). In addition, they can be operated in high magnetic fields to support PET/MR imaging. Utilizing a multi-step simulation process, we determined the intrinsic spatial resolution characteristics for a variety of detector configurations. The crystal was always modeled as a 48.8 mm by 48.8 mm by 15 mm monolithic slab of a lutetium-based scintillator. The SES design was evaluated via simulation for three different two-dimensional MAPD array sizes: 8×8 with 5.8×5.8 mm(2) pads; 12×12 with 3.8×3.8 mm(2) pads; and 16×16 with 2.8×2.8 mm(2) pads. To reduce the number of signal channels row-column summing readout was explored for the 12×12 and 16×16 channel array devices. The intrinsic spatial resolution for the 8×8 MAPD array is 0.88 mm FWHM in X and Y, and 1.83 mm FWHM in Z (i.e., DOI). Comparing the results versus using a conventional design with the photosensors on the backside of the crystal, an average improvement of ~24% in X and Y and 20% in Z is achieved. The X, Y intrinsic spatial resolution improved to 0.66 mm and 0.65 mm FWHM for the 12×12 and 16×16 MAPDs using row-column readout. Using the 12×12 and 16×16 arrays also led to a slight improvement in the DOI positioning accuracy.

  8. Small animal PET based on 16x16 TSV-MPPCs and monolithic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Antonio; Aguilar, Albert Talens; Conde, Pablo; Hernadez, Liczandro Hernadez; Vidal San Sebastian, Luis Fernando [Institute for Instrumentation in Molecular Imaging, i3M-CSIC, Valencia (Spain); Salbador, Carlos Correcher; Solsona, Cesar Molinos [Oncovision, Valencia (Spain); Junge, Sven; Lankes, Konrad [Bruker BioSpin (Germany); Benlloch, Jose Maria [Institute for Instrumentation in Molecular Imaging, i3M-CSIC, Valencia (Spain)

    2015-05-18

    In this work we present the design of a small animal PET based on 8 high-density arrays of MPPCs and monolithic scintillators. The MPPCs arrays are composed of 16x16 TSV-type (3x3 mm{sup 2}) elements covering a rough active area of 5x5 cm{sup 2}. A single LYSO block with a thickness of 10mm has been mounted on each detector. Black paint has been applied to the entrance and lateral faces of the crystal to preserve the scintillation light distribution. The axial and transaxial FOVs of one ring are 48 mm and 80 mm, respectively. Each MPPC array has been directly attached to a resistive readout circuit that provides outputs for each row and column of the array. These 32 signals are read with flexible boards 30 cm apart from the PET detector without any additional connectors in between. The PET-system is intended for in-line acquisition in front of MR scanners and as PET-insert inside the sensitive MRI volume. For this purpose, it is necessary to avoid magnetic sensible materials, such as nickel, and to prevent eddy currents in metallic structures induced by the MRI gradients. All detectors are air cooled and kept at temperatures of approximately 20{sup o}C with a variation below 0.05{sup o}C. The intrinsic resolution is 2.2 mm at the crystal center (averaged over all 2.6 mm) when Center of Gravity methods are used to resolve the impact position. This value is about a factor 1.5 better than results obtained with the H8500 PSPMT (64 PADs) and similar scintillators. With an improved collimator with holes with only 0.8mm diameter and a length of 70 mm, an intrinsic detector resolution of 1.1mm was reached. The energy resolutions of ROIs of 1x1 cm{sup 2} showed FWHM values in the range of 14%.

  9. Impact on the Spatial Resolution Performance of a Monolithic Crystal PET Detector Due to Different Sensor Parameters.

    Science.gov (United States)

    Li, Xiaoli; Lockhart, Cate; Lewellen, Tom K; Miyaoka, Robert S

    2009-10-24

    The performance characteristics of a monolithic crystal PET detector utilizing a novel sensor on the entrance surface (SES) design is reported. To facilitate this design, we propose to utilize a 2D silicon photomultiplier (SiPM) array device. SiPMs are a form of Geiger-Muller mode avalanche photodiodes (GMAPD) that can provide signal gain similar to a photomultiplier tube (PMT). Since these devices are still under active development, their performance parameters are changing. Using a multi-step simulation process, we investigated how different SiPM parameters affect the performance of a monolithic crystal PET detector. These parameters include gain variability between different channels; gain instability; and dark count noise. The detector simulated was a 49.6 mm by 49.6 mm by 15 mm LYSO crystal detector readout by a 16 by 16 array of 2.8 mm by 2.8 mm SiPM elements. To reduce the number of signal channels that need to be collected, the detector utilizes row-column summing. A statistics based positioning method is used for event positioning and depth of interaction (DOI) decoding. Of the variables investigated, the dark count noise had the largest impact on the intrinsic spatial resolution. Gain differences of 5-10% between detector calibration and detector testing had a modest impact on the intrinsic spatial resolution performance and led to a slight bias in positioning. There was no measurable difference with a gain variability of up to 25% between the individual SiPM channels. Based upon these results we are planning to cool our detectors below room temperature to reduce dark count noise and to actively control the temperature of the SiPMs to reduce drifts in gain over time.

  10. Development of a large-area monolithic 4x4 MPPC array for a future PET scanner employing pixelized Ce:LYSO and Pr:LuAG crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kato, T., E-mail: katou.frme.8180@asagi.waseda.j [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Kataoka, J.; Nakamori, T.; Miura, T.; Matsuda, H. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Sato, K.; Ishikawa, Y.; Yamamura, K.; Kawabata, N. [Solid State Division, Hamamatsu Photonics K. K., 1126-1, Ichino-cho, Hamamatsu, Shizuoka (Japan); Ikeda, H.; Sato, G. [ISAS/JAXA, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara-shi, Kanagawa (Japan); Kamada, K. [Materials Research Laboratory, Furukawa Co., Ltd., 1-25-13, Kannondai, Tsukuba, Ibaraki 305-0856 (Japan)

    2011-05-11

    We have developed a new type of large-area monolithic Multi-Pixel Photon Counter (MPPC) array consisting of a 4x4 matrix of 3x3 mm{sup 2} pixels. Each pixel comprises 3600 Geiger mode avalanche photodiodes (APDs) that achieve an average gain of 9.68x10{sup 5} at 71.9 V at 0 {sup o}C with variations of only {+-}7.2% over 4x4 pixels. Excellent uniformity was also obtained for photon detection efficiencies (PDE) of {+-}6.4%, whilst dark count rates at the single photoelectron (1 p.e.) level amounted to {approx_equal}2Mcps/pixel, measured at 0 {sup o}C. As the first step toward using the device in scintillation photon detectors, we fabricated a prototype gamma-ray camera consisting of an MPPC array optically coupled with a scintillator matrix, namely a 4x4 array of 3x3 x10 mm{sup 3} crystals. Specifically, we tested the performance with Ce-doped (Lu, Y){sub 2}(SiO{sub 4})O (Ce:LYSO), Pr-doped Lu{sub 3}Al{sub 5}O{sub 12} (Pr:LuAG) and 'surface coated' Pr:LuAG (Pr:LuAG (WLS)) matrices whereby the emission peak of Pr:LuAG was shifted from 310 to 420 nm via a wavelength shifter (WLS). Average energy resolutions of 13.83%, 14.70% and 13.96% (FWHM) were obtained for 662 keV gamma-rays, as measured at 0 {sup o}C with Ce:LYSO, Pr:LuAG and Pr:LuAG (WLS) scintillator matrices, respectively. We confirmed that the effective PDE for Pr:LuAG (WLS) had improved by more than 30% compared to original, non-coated Pr:LuAG matrix. These results suggest that a large-area monolithic MPPC array developed here could be promising for future medical imaging, particularly in positron emission tomography (PET).

  11. Integrated optical and nuclear simulation of a monolithic LYSO:Ce based PET detector module

    Science.gov (United States)

    Játékos, B.; Patay, G.; Lőrincz, E.; Erdei, G.

    2017-05-01

    In the recent years new digital photon counter devices (also known as silicon photomultipliers, SiPMs) were designed and manufactured to be used specifically in positron emission tomography (PET) scanners. Finely pixelated SiPM arrays have opened new opportunities in PET detector development, such as the utilization of monolithic scintillator crystals. We worked out a simulation tool (SCOPE2) to assist the optimization and characterization of such PET detector modules. In the present paper we report the first application of SCOPE2 on the performance evaluation of a prototype PET detector module. The PET detector is based on monolithic LYSO:Ce scintillator crystal and a fully digital, silicon photon-counter, SPADnet-I. A new interface has been developed for SCOPE2 to access GATE simulation results. A combination of GATE and SCOPE2 was used to simulate excitation of the prototype PET detector with an electronically collimated γ -beam. Measurement results from the collimated γ-beam experiment were compared with the combined simulation. A good agreement was observed in the tendencies of total count spectrum and point of interaction distribution. We used the performance evaluation to understand and explain the measurement results in detail.

  12. A PET detector module with monolithic crystal, single end readout, SiPM array and high depth-of-interaction resolution

    Science.gov (United States)

    Zhang, H.; Zhou, R.; Yang, C.

    2016-08-01

    Depth of interaction (DOI) technology can improve the spatial resolution of nuclear medicine imaging system which uses scintillation detectors such as Positron Emission Tomography (PET). In this paper, a prototype detector module with DOI capability is established to make complementary characteristic tests on an existing method and to improve the experimental performance using the same method. We investigate the gamma incident surface and incident angle effects on the positioning method with our model in simulations and evaluate its 3-D positioning results in experiment. It shows that the positioning results are highly affected by the gamma incident surface and incident angle. The 137Cs energy resolution is 12.1% and the DOI resolution is estimated at 2.26 mm in average by our detector in experiment.

  13. Performance study of a PET scanner based on monolithic scintillators for different DoI-dependent methods

    Science.gov (United States)

    Preziosi, E.; Sánchez, S.; González, A. J.; Pani, R.; Borrazzo, C.; Bettiol, M.; Rodriguez-Alvarez, M. J.; González-Montoro, A.; Moliner, L.; Benlloch, J. M.

    2016-12-01

    One of the technical objectives of the MindView project is developing a brain-dedicated PET insert based on monolithic scintillation crystals. It will be inserted in MRI systems with the purpose to obtain simultaneous PET and MRI brain images. High sensitivity, high image quality performance and accurate detection of the Depth-of-Interaction (DoI) of the 511keV photons are required. We have developed a DoI estimation method, dedicated to monolithic scintillators, allowing continuous DoI estimation and a DoI-dependent algorithm for the estimation of the photon planar impact position, able to improve the single module imaging capabilities. In this work, through experimental measurements, the proposed methods have been used for the estimation of the impact positions within the monolithic crystal block. We have evaluated the PET system performance following the NEMA NU 4-2008 protocol by reconstructing the images using the STIR 3D platform. The results obtained with two different methods, providing discrete and continuous DoI information, are compared with those obtained from an algorithm without DoI capabilities and with the ideal response of the detector. The proposed DoI-dependent imaging methods show clear improvements in the spatial resolution (FWHM) of reconstructed images, allowing to obtain values from 2mm (at the center FoV) to 3mm (at the FoV edges).

  14. Performance of a DOI-encoding small animal PET system with monolithic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Carles, M., E-mail: montcar@ific.uv.es [Instituto de Instrumentacion para Imagen Molecular(I3M), Centro mixto CSIC-Universitat Politecnica de Valencia- IEMAT, Camino de Vera s/n, 46020 Valencia (Spain); Lerche, Ch.W. [Department X-Ray Imaging Systems, Philips Research Europe, Weisshausstrasse 2, D-52066 Aachen (Germany); Sanchez, F.; Orero, A.; Moliner, L.; Soriano, A.; Benlloch, J.M. [Instituto de Instrumentacion para Imagen Molecular(I3M), Centro mixto CSIC-Universitat Politecnica de Valencia- IEMAT, Camino de Vera s/n, 46020 Valencia (Spain)

    2012-12-11

    PET systems designed for specific applications require high resolution and sensitivity instrumentation. In dedicated system design smaller ring diameters and deeper crystals are widely used in order to increase the system sensitivity. However, this design increases the parallax error, which degrades the spatial image resolution gradually from the center to the edge of the field-of-view (FOV). Our group has designed a depth of interaction(DOI)-encoding small animal PET system based on monolithic crystals. In this work we investigate the restoration of radial resolution for transaxially off-center sources using the DOI information provided by our system. For this purpose we have designed a support for point like sources adapted to our system geometry that allows a spatial compression and resolution response study. For different point source radial positions along vertical and horizontal axes of a FOV transaxial plane we compare the results obtained by three methods: without DOI information, with the DOI provided by our system and with the assumption that all the {gamma}-rays interact at half depth of the crystal thickness. Results show an improvement of the mean resolution of 10% with the half thickness assumption and a 16% achieved using the DOI provided by the system. Furthermore, a 10% restoration of the resolution uniformity is obtained using the half depth assumption and an 18% restoration using measured DOI.

  15. A crystal identification method for monolithic phoswich detectors based on scintillation light distribution

    Science.gov (United States)

    Preziosi, E.; Pani, R.; Trigila, C.; Polito, C.; Bettiol, M.; Borrazzo, C.; Cinti, M. N.; Fabbri, A.; Pellegrini, R.; Pani, R.

    2016-12-01

    Phoswich detectors based on scintillation crystals are widely diffused for both PET and SPECT applications. In order to separate the signals arising from different layers many methods have been proposed in literature. Separation of the layers commonly relies on time discrimination or pulse height discrimination. In this work, by means of experimental measurement on a phoswich detector based on Lanthanum Bromide and Lutetium Fine Silicate monolithic crystals, a novel method allowing to separate signals coming from different layers has been evaluated. The main feature of this method, specifically developed for phoswich based on monolithic scintillation crystals, is the discrimination capability based on the scintillation light distribution shape. For this reason, the findings that will be shown could be easily extended to whatever combination of scintillator, independently from their decay time or light yield.

  16. Towards monolithic scintillator based TOF-PET systems: practical methods for detector calibration and operation

    Science.gov (United States)

    Borghi, Giacomo; Tabacchini, Valerio; Schaart, Dennis R.

    2016-07-01

    Gamma-ray detectors based on thick monolithic scintillator crystals can achieve spatial resolutions  published k-NN 1D method. Also, the procedures for estimating the DOI and time of interaction are revised to enable full detector calibration by means of fan-beam or flood irradiations only. Moreover, a new technique is presented to allow the use of events in which some of the photosensor pixel values and/or timestamps are missing (e.g. due to dead time), so as to further increase system sensitivity. The accelerated methods were tested on a monolithic scintillator detector specifically developed for clinical PET applications, consisting of a 32 mm  ×  32 mm  ×  22 mm LYSO : Ce crystal coupled to a digital photon counter (DPC) array. This resulted in a spatial resolution of 1.7 mm FWHM, an average DOI resolution of 3.7 mm FWHM, and a CRT of 214 ps. Moreover, the possibility of using events missing the information of up to 16 out of 64 photosensor pixels is shown. This results in only a small deterioration of the detector performance.

  17. Evaluation of event position reconstruction in monolithic crystals that are optically coupled

    Science.gov (United States)

    Morrocchi, M.; Hunter, W. C. J.; Del Guerra, A.; Lewellen, T. K.; Kinahan, P. E.; MacDonald, L. R.; Bisogni, M. G.; Miyaoka, R. S.

    2016-12-01

    A PET detector featuring a pseudo-monolithic crystal is being developed as a more cost-effective alternative to a full monolithic crystal PET detector. This work evaluates different methods to localize the scintillation events in quartered monolithic crystals that are optically coupled. A semi-monolithic crystal assembly was formed using four 26  ×  26  ×  10 mm3 LYSO crystals optically coupled together using optical adhesive, to mimic a 52  ×  52  ×  10 mm3 monolithic crystal detector. The crystal assembly was coupled to a 64-channel multi-anode photomultiplier tube using silicon grease. The detector was calibrated using a 34  ×  34 scan grid. Events were first filtered and depth separated using a multi-Lorentzian fit to the collected light distribution. Next, three different techniques were explored to generate the look up tables for the event positioning. The first technique was ‘standard interpolation’ across the interface. The second technique was ‘central extrapolation’, where a bin was placed at the midpoint of the interface and events positioned within the interface region were discarded. The third technique used a ‘central overlap’ method where an extended region was extrapolated at each interface. Events were then positioned using least-squares minimization and maximum likelihood methods. The least-squares minimization applied to the look up table generated with the standard interpolation technique had the best full width at half maximum (FWHM) intrinsic spatial resolution and the lowest bias. However, there were discontinuities in the event positioning that would most likely lead to artifacts in the reconstructed image. The central extrapolation technique also had discontinuities and a 30% sensitivity loss near the crystal-crystal interfaces. The central overlap technique had slightly degraded performance metrics, but it still provided ~2.1 mm intrinsic spatial resolution at the crystal-crystal

  18. 3D photon impact determination in monolithic crystals based on autocorrelation filters and RTP methods

    Energy Technology Data Exchange (ETDEWEB)

    Conde, Pablo; Gonzalez, Antonio [Institute for Instrumentation in Molecular Imaging, I3M-CSIC, Valencia (Spain); Bettiol, Marco; Fabbri, Andrea; Pani, Roberto [Department of Molecular Medicine, Sapienza University of Rome (Italy); Benlloch Baviera, José María; Talens Aguilar, Albert; Hernandez, Liczandro; Sanchez, Filomeno [Institute for Instrumentation in Molecular Imaging, I3M-CSIC, Valencia (Spain)

    2015-05-18

    In PET detectors based on monolithic scintillators, the photon impact position can be estimated from the light intensity distribution (LD) on the photodetector pixels. Typically, there is a poor estimation of the interaction positions towards the edges when linear algorithms such as Center of Gravity (CoG) are used. We present a novel method to determine the interaction coordinates in thick monolithic crystals filtering the digitized LDs from each gamma-event by means of an autocorrelation filter and the raise to power (RTP) positioning algorithm to reduce the border effects. The experimental setup was based on two detector blocks based on monolithic LYSO scintillator crystals (50x50x20 mm{sup 3}). Each crystal is coupled to a SiPMs array as 12x12 photosensors and an electronic readout that outputs information of each SiPM row and column. Between the detector blocks, a collimated array of 9x9 {sup 22}Na sources, separated 5 mm each other, was placed. The optimum power to use in the RTP positioning algorithm was determined using the third order intercept point (IP3) from plots of the measured coordinates versus known positions. After applying the autocorrelation and RTP fifth to the data, we found an improvement of the spatial resolution from 2.5 mm when CoG is used, to 1.2 mm in the crystal center region. In this work we show how to accurately resolve 3D photon impact coordinates in thick monolithic crystals using autocorrelation filters merged with RTP methods. After applying the new approach it is possible to accurately resolve impacts close to the entrance of 20 mm thick LYSO scintillators. The reached spatial resolution at any photon depth of interaction is comparable with state-of-the-art crystal array approaches with the advantage of the proposed work to also provide continuous depth of interaction information.

  19. High performance detector head for PET and PET/MR with continuous crystals and SiPMs

    Energy Technology Data Exchange (ETDEWEB)

    Llosá, G., E-mail: gabriela.llosa@ific.uv.es [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Barrillon, P. [Laboratoire de L' Accélérateur Linéaire (LAL), Orsay (France); Barrio, J. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Bisogni, M.G. [Dipartimento di Fisica “E. Fermi”, Università di Pisa and INFN Pisa, Pisa (Italy); Cabello, J. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Del Guerra, A. [Dipartimento di Fisica “E. Fermi”, Università di Pisa and INFN Pisa, Pisa (Italy); Etxebeste, A.; Gillam, J.E.; Lacasta, C.; Oliver, J.F. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Rafecas, M. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Departamento de Física Atómica, Molecular y Nuclear, Universitat de València, Valencia (Spain); Solaz, C.; Stankova, V. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); La Taille, C. de [Laboratoire de L' Accélérateur Linéaire (LAL), Orsay (France)

    2013-02-21

    A high resolution PET detector head for small animal PET applications has been developed. The detector is composed of a 12mm×12mm continuous LYSO crystal coupled to a 64-channel monolithic SiPM matrix from FBK-irst. Crystal thicknesses of 5 mm and 10 mm have been tested, both yielding an intrinsic spatial resolution around 0.7 mm FWHM with a position determination algorithm that can also provide depth-of-interaction information. The detectors have been tested in a rotating system that makes it possible to acquire tomographic data and reconstruct images of {sup 22}Na sources. An image reconstruction method specifically adapted for continuous crystals has been employed. The Full Width at Half Maximum measured from a point source reconstructed with ML–EM was 0.7 mm with the 5 mm crystal and 0.8 mm with the 10 mm crystal.

  20. Improved Nearest Neighbor Methods for Gamma Photon Interaction Position Determination in Monolithic Scintillator PET Detectors

    NARCIS (Netherlands)

    van Dam, Herman T.; Seifert, Stefan; Vinke, Ruud; Dendooven, Peter; Lohner, Herbert; Beekman, Freek J.; Schaart, Dennis R.

    2011-01-01

    Monolithic scintillator detectors have been shown to provide good performance and to have various practical advantages for use in PET systems. Excellent results for the gamma photon interaction position determination in these detectors have been obtained by means of the k-nearest neighbor (k-NN)

  1. Performance of a SiPM based semi-monolithic scintillator PET detector

    Science.gov (United States)

    Zhang, Xianming; Wang, Xiaohui; Ren, Ning; Kuang, Zhonghua; Deng, Xinhan; Fu, Xin; Wu, San; Sang, Ziru; Hu, Zhanli; Liang, Dong; Liu, Xin; Zheng, Hairong; Yang, Yongfeng

    2017-10-01

    A depth encoding PET detector module using semi-monolithic scintillation crystal single-ended readout by a SiPM array was built and its performance was measured. The semi-monolithic scintillator detector consists of 11 polished LYSO slices measuring 1  ×  11.6  ×  10 mm3. The slices are glued together with enhanced specular reflector (ESR) in between and outside of the slices. The bottom surface of the slices is coupled to a 4  ×  4 SiPM array with a 1 mm light guide and silicon grease between them. No reflector is used on the top surface and two sides of the slices to reduce the scintillation photon reflection. The signals of the 4  ×  4 SiPM array are grouped along rows and columns separately into eight signals. Four SiPM column signals are used to identify the slices according to the center of the gravity of the scintillation photon distribution in the pixelated direction. Four SiPM row signals are used to estimate the y (monolithic direction) and z (depth of interaction) positions according to the center of the gravity and the width of the scintillation photon distribution in the monolithic direction, respectively. The detector was measured with 1 mm sampling interval in both the y and z directions with electronic collimation by using a 0.25 mm diameter 22Na point source and a 1  ×  1  ×  20 mm3 LYSO crystal detector. An average slice based energy resolution of 14.9% was obtained. All slices of 1 mm thick were clearly resolved and a detector with even thinner slices could be used. The y positions calculated with the center of gravity method are different for interactions happening at the same y, but different z positions due to depth dependent edge effects. The least-square minimization and the maximum likelihood positioning algorithms were developed and both methods improved the spatial resolution at the edges of the detector as compared with the center of gravity method. A mean absolute error

  2. A novel, SiPM-array-based, monolithic scintillator detector for PET.

    Science.gov (United States)

    Schaart, Dennis R; van Dam, Herman T; Seifert, Stefan; Vinke, Ruud; Dendooven, Peter; Löhner, Herbert; Beekman, Freek J

    2009-06-07

    Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e.g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanche photodiodes. Here we present a novel detector design with DOI correction, in which a position-sensitive SiPM array is used to read out a monolithic scintillator. Initial characterization of a prototype detector consisting of a 4 x 4 SiPM array coupled to either the front or back surface of a 13.2 mm x 13.2 mm x 10 mm LYSO:Ce(3+) crystal shows that front-side readout results in significantly better performance than conventional back-side readout. Spatial resolutions <1.6 mm full-width-at-half-maximum (FWHM) were measured at the detector centre in response to an approximately 0.54 mm FWHM diameter test beam. Hardly any resolution losses were observed at angles of incidence up to 45 degrees , demonstrating excellent DOI correction. About 14% FWHM energy resolution was obtained. The timing resolution, measured in coincidence with a BaF(2) detector, equals 960 ps FWHM.

  3. A novel, SiPM-array-based, monolithic scintillator detector for PET

    Energy Technology Data Exchange (ETDEWEB)

    Schaart, Dennis R; Dam, Herman T van; Seifert, Stefan; Beekman, Freek J [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Vinke, Ruud; Dendooven, Peter; Loehner, Herbert [Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747 AA, Groningen (Netherlands)], E-mail: d.r.schaart@tudelft.nl

    2009-06-07

    Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e.g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanche photodiodes. Here we present a novel detector design with DOI correction, in which a position-sensitive SiPM array is used to read out a monolithic scintillator. Initial characterization of a prototype detector consisting of a 4 x 4 SiPM array coupled to either the front or back surface of a 13.2 mm x 13.2 mm x 10 mm LYSO:Ce{sup 3+} crystal shows that front-side readout results in significantly better performance than conventional back-side readout. Spatial resolutions <1.6 mm full-width-at-half-maximum (FWHM) were measured at the detector centre in response to an {approx}0.54 mm FWHM diameter test beam. Hardly any resolution losses were observed at angles of incidence up to 45 deg., demonstrating excellent DOI correction. About 14% FWHM energy resolution was obtained. The timing resolution, measured in coincidence with a BaF{sub 2} detector, equals 960 ps FWHM.

  4. Heterogeneous Monolithic Integration of Single-Crystal Organic Materials.

    Science.gov (United States)

    Park, Kyung Sun; Baek, Jangmi; Park, Yoonkyung; Lee, Lynn; Hyon, Jinho; Koo Lee, Yong-Eun; Shrestha, Nabeen K; Kang, Youngjong; Sung, Myung Mo

    2017-02-01

    Manufacturing high-performance organic electronic circuits requires the effective heterogeneous integration of different nanoscale organic materials with uniform morphology and high crystallinity in a desired arrangement. In particular, the development of high-performance organic electronic and optoelectronic devices relies on high-quality single crystals that show optimal intrinsic charge-transport properties and electrical performance. Moreover, the heterogeneous integration of organic materials on a single substrate in a monolithic way is highly demanded for the production of fundamental organic electronic components as well as complex integrated circuits. Many of the various methods that have been designed to pattern multiple heterogeneous organic materials on a substrate and the heterogeneous integration of organic single crystals with their crystal growth are described here. Critical issues that have been encountered in the development of high-performance organic integrated electronics are also addressed.

  5. Innovative PET detector concept based on SiPMs and continuous crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Martinez, A.J., E-mail: agonzalez@i3m.upv.es [Instituto de Instrumentacion para Imagen Molecular (I3M), Centro Mixto UPV - CSIC - CIEMAT, Camino de Vera s/n, 46022 Valencia (Spain); ONCOVISION (GEM-Imaging S.A.), 46012 Valencia (Spain); Peiro Cloquell, A.; Sanchez Martinez, F.; Vidal San Sebastian, L.F.; Benlloch Baviera, J.M. [Instituto de Instrumentacion para Imagen Molecular (I3M), Centro Mixto UPV - CSIC - CIEMAT, Camino de Vera s/n, 46022 Valencia (Spain)

    2012-12-11

    The use of Silicon Photomultipliers (SiPM) has been proposed for Positron Emission Tomography (PET) readout because they are hardly affected by magnetic fields and their time response enables Time of Flight measurements. This work proposes an array of SiPM to be coupled to a monolithic LYSO crystal by means of a series of optical devices. The emitted light distribution by the scintillation crystal will be accurately determined using an Application Specific Integrated Circuit. The described sensor block aims to determine the planar coordinates and depth of interaction of the gamma ray with sub-millimetrical precision. In this work we present the initial studies regarding edge effects due to thick monolithic crystals and how to overcome these limitations by means of optical devices namely faceplates and light concentrators. We will also discuss on the alignment of such optical devices with the SiPMs.

  6. Effect of nucleating agents on crystallization kinetics of PET

    Directory of Open Access Journals (Sweden)

    2007-04-01

    Full Text Available Effects of three nucleating agents concluding talc, sodium benzoate (SB and an ionomer (Ion., Na+ on crystallization of poly(ethylene terephthalate (PET were studied by differential scanning calorimetry (DSC and polarized optical microscope (POM, the parameters of crystallization kinetics were obtained through Avrami and Ozawa equations. The fold surface free energy σe of pure PET and PET/nucleating agent blends were calculated by Hoffman-Lauritzen theory. The results indicate that the three kinds of nucleating agents increase the crystallization rate constant through promoting their nucleating effect for PET crystallization, among which SB is the best one with the same content. The crystallization mode of PET might shift from three-dimensional growth to two-dimensional growth by the addition of the nucleating agents. The values of σe of PET/nucleating agent blends are much less than that of pure PET, and PET/SB (99:1 blend has the least value of σe (18.2 mJ/m2. The conclusion based on Hoffman theory is similar to the analysis by Avrami and Ozawa equations.

  7. Monolithic LaBr3 : Ce crystals on silicon photomultiplier arrays for time-of-flight positron emission tomography

    NARCIS (Netherlands)

    Seifert, Stefan; van Dam, Herman T.; Huizenga, Jan; Vinke, Ruud; Dendooven, Peter; Löhner, Herbert; Schaart, Dennis R.

    2012-01-01

    Positron emission tomography detectors based on monolithic scintillation crystals exhibit good spatial and energy resolution, intrinsically provide depth-of-interaction information, have high gamma-photon capture efficiency, and may reduce the manufacturing costs compared to pixelated crystal

  8. Monolithic LaBr3 : Ce crystals on silicon photomultiplier arrays for time-of-flight positron emission tomography

    NARCIS (Netherlands)

    Seifert, Stefan; van Dam, Herman T.; Huizenga, Jan; Vinke, Ruud; Dendooven, Peter; Löhner, Herbert; Schaart, Dennis R.

    2012-01-01

    Positron emission tomography detectors based on monolithic scintillation crystals exhibit good spatial and energy resolution, intrinsically provide depth-of-interaction information, have high gamma-photon capture efficiency, and may reduce the manufacturing costs compared to pixelated crystal arrays

  9. Improved image quality using monolithic scintillator detectors with dual-sided readout in a whole-body TOF-PET ring: a simulation study

    Science.gov (United States)

    Tabacchini, Valerio; Surti, Suleman; Borghi, Giacomo; Karp, Joel S.; Schaart, Dennis R.

    2017-03-01

    We have recently built and characterized the performance of a monolithic scintillator detector based on a 32 mm  ×  32 mm  ×  22 mm LYSO:Ce crystal read out by digital silicon photomultiplier (dSiPM) arrays coupled to the crystal front and back surfaces in a dual-sided readout (DSR) configuration. The detector spatial resolution appeared to be markedly better than that of a detector consisting of the same crystal with conventional back-sided readout (BSR). Here, we aim to evaluate the influence of this difference in the detector spatial response on the quality of reconstructed images, so as to quantify the potential benefit of the DSR approach for high-resolution, whole-body time-of-flight (TOF) positron emission tomography (PET) applications. We perform Monte Carlo simulations of clinical PET systems based on BSR and DSR detectors, using the results of our detector characterization experiments to model the detector spatial responses. We subsequently quantify the improvement in image quality obtained with DSR compared to BSR, using clinically relevant metrics such as the contrast recovery coefficient (CRC) and the area under the localized receiver operating characteristic curve (ALROC). Finally, we compare the results with simulated rings of pixelated detectors with DOI capability. Our results show that the DSR detector produces significantly higher CRC and increased ALROC values than the BSR detector. The comparison with pixelated systems indicates that one would need to choose a crystal size of 3.2 mm with three DOI layers to match the performance of the BSR detector, while a pixel size of 1.3 mm with three DOI layers would be required to get on par with the DSR detector.

  10. A practical method for depth of interaction determination in monolithic scintillator PET detectors

    Energy Technology Data Exchange (ETDEWEB)

    Van Dam, Herman T; Seifert, Stefan; Beekman, Freek J; Schaart, Dennis R [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Vinke, Ruud; Dendooven, Peter; Loehner, Herbert, E-mail: h.t.vandam@tudelft.nl [Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands)

    2011-07-07

    Several new methods for determining the depth of interaction (DOI) of annihilation photons in monolithic scintillator detectors with single-sided, multi-pixel readout are investigated. The aim is to develop a DOI decoding method that allows for practical implementation in a positron emission tomography system. Specifically, calibration data, obtained with perpendicularly incident gamma photons only, are being used. Furthermore, neither detector modifications nor a priori knowledge of the light transport and/or signal variances is required. For this purpose, a clustering approach is utilized in combination with different parameters correlated with the DOI, such as the degree of similarity to a set of reference light distributions, the measured intensity on the sensor pixel(s) closest to the interaction position and the peak intensity of the measured light distribution. The proposed methods were tested experimentally on a detector comprised of a 20 mm x 20 mm x 12 mm polished LYSO:Ce crystal coupled to a 4 x 4 multi-anode photomultiplier. The method based on the linearly interpolated measured intensities on the sensor pixels closest to the estimated (x, y)-coordinate outperformed the other methods, yielding DOI resolutions between {approx}1 and {approx}4.5 mm FWHM depending on the DOI, the (x, y) resolution and the amount of reference data used.

  11. Maximum-likelihood Estimation of 3D Event Position in Monolithic Scintillation Crystals: Experimental Results

    OpenAIRE

    Moore, S K; Hunter, W C J; Furenlid, L.R.; Barrett, H. H.

    2007-01-01

    We present a simple 3D event position-estimation method using raw list-mode acquisition and maximum-likelihood estimation in a modular gamma camera with a thick (25mm) monolithic scintillation crystal. This method involves measuring 2D calibration scans with a well-collimated 511 keV source and fitting each point to a simple depth-dependent light distribution model. Preliminary results show that angled collimated beams appear properly reconstructed.

  12. Monolithic phononic crystals with a surface acoustic band gap from surface phonon-polariton coupling.

    Science.gov (United States)

    Yudistira, D; Boes, A; Djafari-Rouhani, B; Pennec, Y; Yeo, L Y; Mitchell, A; Friend, J R

    2014-11-21

    We theoretically and experimentally demonstrate the existence of complete surface acoustic wave band gaps in surface phonon-polariton phononic crystals, in a completely monolithic structure formed from a two-dimensional honeycomb array of hexagonal shape domain-inverted inclusions in single crystal piezoelectric Z-cut lithium niobate. The band gaps appear at a frequency of about twice the Bragg band gap at the center of the Brillouin zone, formed through phonon-polariton coupling. The structure is mechanically, electromagnetically, and topographically homogeneous, without any physical alteration of the surface, offering an ideal platform for many acoustic wave applications for photonics, phononics, and microfluidics.

  13. Hierarchically structured monolithic silicalite-1 consisting of crystallized nanoparticles and its performance in the Beckmann rearrangement of cyclohexanone oxime.

    Science.gov (United States)

    Li, Wen-Cui; Lu, An-Hui; Palkovits, Regina; Schmidt, Wolfgang; Spliethoff, Bernd; Schüth, Ferdi

    2005-09-14

    In this study, we present a synthetic pathway for the fabrication of self-supporting zeolite monoliths consisting of crystallized nanoparticles. A resorcinol-formaldehyde-based organic aerogel is used as a template, and silicalite-1 is used as the zeolite example. The silicalite-1 monoliths obtained consist of individual well-defined zeolite nanocrystals with sizes of 30-40 nm. The monoliths exhibit a high mechanical stability and have hierarchical porosity, with micropores within the zeolite particles, a mesopore system formed by the packing of the nanoparticles, and a macropore system on the monolith level. Such monolithic zeolites show high selectivity typically above 80% to epsilon-caprolactam combined with a high rate of reaction of 0.46 g(caprolactame)/(g(catalyst).h) in the Beckmann rearrangement of cyclohexanone oxime.

  14. Silicon Photomultipliers and Monolithic Scintillators for Time-of-Flight PET

    NARCIS (Netherlands)

    Seifert, S.

    2012-01-01

    Positron emission tomography (PET) is a nuclear medical imaging modality. Its aim is to visualize the 3-dimensional distribution of a radiopharmaceutical (also called the tracer) within a patient (clinical PET) or test-animal (in case of preclinical investigations). The information that can be obtai

  15. Silicon Photomultipliers and Monolithic Scintillators for Time-of-Flight PET

    NARCIS (Netherlands)

    Seifert, S.

    2012-01-01

    Positron emission tomography (PET) is a nuclear medical imaging modality. Its aim is to visualize the 3-dimensional distribution of a radiopharmaceutical (also called the tracer) within a patient (clinical PET) or test-animal (in case of preclinical investigations). The information that can be obtai

  16. Silicon Photomultipliers and Monolithic Scintillators for Time-of-Flight PET

    NARCIS (Netherlands)

    Seifert, S.

    2012-01-01

    Positron emission tomography (PET) is a nuclear medical imaging modality. Its aim is to visualize the 3-dimensional distribution of a radiopharmaceutical (also called the tracer) within a patient (clinical PET) or test-animal (in case of preclinical investigations). The information that can be

  17. Highly efficient coupling between a monolithically integrated photonic crystal cavity and a bus waveguide

    Science.gov (United States)

    Debnath, Kapil; Welna, Karl; Ferrera, Marcello; Deasy, Kieran; Lidzey, David; Krauss, Thomas F.; O'Faolain, Liam

    2012-01-01

    We experimentally demonstrate a new optical filter design comprising of a photonic crystal cavity and a low index bus waveguide which are monolithically integrated on a silicon-on-insulator (SOI) platform. We have fabricated oxide clad PhC cavities with a silicon nitride waveguide positioned directly above, such that there is an overlap between the evanescent tails of the two modes. We have realised an extinction ratio of 7.5dB for cavities with total Q of 50,000.

  18. New scintillating crystals for PET scanners

    CERN Document Server

    Lecoq, P

    2002-01-01

    Systematic R&D on basic mechanism in inorganic scintillators, initiated by the Crystal Clear Collaboration at CERN 10 years ago, has contributed not to a small amount, to the development of new materials for a new generation of medical imaging devices with increased resolution and sensitivity. The first important requirement for a scintillator to be used in medical imaging devices is the stopping power for the given energy range of X and gamma rays to be considered, and more precisely the conversion efficiency. A high light yield is also mandatory to improve the energy resolution, which is essentially limited by the photostatistics and the electronic noise at these energies. A short scintillation decay time allows to reduce the dead time and therefore to increase the limiting counting rate. When all these requirements are fulfilled the sensitivity and image contrast are increased for a given patient dose, or the dose can be reduced. Examples of new materials under development by the Crystal Clear Collabor...

  19. A 32 mm  ×  32 mm  ×  22 mm monolithic LYSO:Ce detector with dual-sided digital photon counter readout for ultrahigh-performance TOF-PET and TOF-PET/MRI

    Science.gov (United States)

    Borghi, Giacomo; Peet, Bart Jan; Tabacchini, Valerio; Schaart, Dennis R.

    2016-07-01

    New applications for positron emission tomography (PET) and combined PET/magnetic resonance imaging (MRI) are currently emerging, for example in the fields of neurological, breast, and pediatric imaging. Such applications require improved image quality, reduced dose, shorter scanning times, and more precise quantification. This can be achieved by means of dedicated scanners based on ultrahigh-performance detectors, which should provide excellent spatial resolution, precise depth-of-interaction (DOI) estimation, outstanding time-of-flight (TOF) capability, and high detection efficiency. Here, we introduce such an ultrahigh-performance TOF/DOI PET detector, based on a 32 mm  ×  32 mm  ×  22 mm monolithic LYSO:Ce crystal. The 32 mm  ×  32 mm front and back faces of the crystal are coupled to a digital photon counter (DPC) array, in so-called dual-sided readout (DSR) configuration. The fully digital detector offers a spatial resolution of ~1.1 mm full width at half maximum (FWHM)/~1.2 mm mean absolute error, together with a DOI resolution of ~2.4 mm FWHM, an energy resolution of 10.2% FWHM, and a coincidence resolving time of 147 ps FWHM. The time resolution closely approaches the best results (135 ps FWHM) obtained to date with small crystals made from the same material coupled to the same DPC arrays, illustrating the excellent correction for optical and electronic transit time spreads that can be achieved in monolithic scintillators using maximum-likelihood techniques for estimating the time of interaction. The performance barely degrades for events with missing data (up to 6 out of 32 DPC dies missing), permitting the use of almost all events registered under realistic acquisition conditions. Moreover, the calibration procedures and computational methods used for position and time estimation follow recently made improvements that make them fast and practical, opening up realistic perspectives for using DSR monolithic

  20. Characterization of a preclinical system of PET Imaging based detectors monolithic Lyso the PET systems; Caracterizacion de un sistema preclinico de imagen PET basado en detectores monoliticos Lyso

    Energy Technology Data Exchange (ETDEWEB)

    Rey, N.; Gomez Rodriguez, F.

    2013-07-01

    Preclinical Type are usually based on segmented to millimetre scale LSO/LYSO detection modules. A tendency of the current systems consists of exploiting light distribution curves reconstruction algorithms to obtain similar spatial resolutions with monolithic blocks of scintillator. the results of the investigation of the properties of this system as the intrinsic spatial resolution, resolution in energy and calibration of the system. (Author)

  1. Compact engineering of path-entangled sources from a monolithic quadratic nonlinear photonic crystal

    CERN Document Server

    Jin, H; Luo, X W; Leng, H Y; Gong, Y X; Zhu, S N

    2013-01-01

    Photonic entangled states lie at the heart of quantum science for the demonstrations of quantum mechanics foundations and supply as a key resource for approaching various quantum technologies. An integrated realization of such states will certainly guarantee a high-degree of entanglement and improve the performance like portability, stability and miniaturization, hence becomes an inevitable tendency towards the integrated quantum optics. Here, we report the compact realization of steerable photonic path-entangled states from a monolithic quadratic nonlinear photonic crystal. The crystal acts as an inherent beam splitter to distribute photons into coherent spatial modes, producing the heralded single-photon even appealing beamlike two-photon path-entanglement, wherein the entanglement is characterized by quantum spatial beatings. Such multifunctional entangled source can be further extended to high-dimensional fashion and multi-photon level as well as involved with other degrees of freedom, which paves a desir...

  2. A novel, SiPM-array-based, monolithic scintillator detector for PET

    NARCIS (Netherlands)

    Schaart, D.R.; Van Dam, H.T.; Seifert, S.; Vinke, R.; Dendooven, P.; Löhner, H.; Beekman, F.J.

    2009-01-01

    Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e.g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanche

  3. A novel, SiPM-array-based, monolithic scintillator detector for PET

    NARCIS (Netherlands)

    Schaart, Dennis R.; van Dam, Herman T.; Seifert, Stefan; Vinke, Ruud; Dendooven, Peter; Beekman, Freek J.; Löhner, H.

    2009-01-01

    Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e. g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as

  4. A novel, SiPM-array-based, monolithic scintillator detector for PET

    NARCIS (Netherlands)

    Schaart, Dennis R.; van Dam, Herman T.; Seifert, Stefan; Vinke, Ruud; Dendooven, Peter; Beekman, Freek J.; Löhner, H.

    2009-01-01

    Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e. g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanch

  5. Microchip laser based on Yb:YAG/V:YAG monolith crystal

    Science.gov (United States)

    Nejezchleb, Karel; Šulc, Jan; Jelínková, Helena; Škoda, Václav

    2016-03-01

    V:YAG crystal was investigated as a passive Q-switch of longitudinally diode-pumped microchip laser, emitting radiation at wavelength 1030.5 nm. This laser was based on diffusion bonded monolith crystal (diameter 3 mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3 mm long) and saturable absorber (V:YAG crystal, 2 mm long, initial transmission 86 % @ 1031 nm). The microchip resonator consisted of dielectric mirrors directly deposited on the monolith surfaces (pump mirror HT @ 968 nm and HR @ 1031 nm on Yb:YAG part, output coupler with reflection 55 % @ 1031 nm on the V:YAG part). For longitudinal CW pumping of Yb:YAG part, a fibre coupled (core diameter 100 μm, NA = 0.22, emission @ 968 nm) laser diode was used. The laser threshold was 3.8W. The laser slope efficiency for output mean in respect to incident pumping was 16 %. The linearly polarized generated transversal intensity beam profile was close to the fundamental Gaussian mode. The generated pulse length, stable and mostly independent on pumping power, was equal to 1.3 ns (FWHM). The single pulse energy was increasing with the pumping power and for the maximum pumping 9.7W it was 78 μJ which corresponds to the pulse peak-power 56 kW. The maximum Yb:YAG/V:YAG microchip laser mean output power of 1W was reached without observable thermal roll-over. The corresponding Q-switched pulses repetition rate was 13.1 kHz.

  6. Estimation of Hoffman-Lauritzen parameters from nonisothermal crystallization kinetics of PET/MWCNT nanocomposites

    Science.gov (United States)

    Gaonkar, Amita; Murudkar, Vrishali; Deshpande, V. D.

    2016-05-01

    Polyethylene terephthalate (PET) and Nucleated PET/ multi-walled carbon nanotubes (MWCNTs) nanocomposites with different MWCNTs loadings were prepared by melt compounding. The influence of the addition of MWCNTs and precipitated PET (p-PET) on the morphology and thermal properties of the nanocomposites was investigated. From Transmission Electronic Microscopy (TEM) and Wide angle X-Ray diffraction (WAXD) study, it can be clearly seen that nanocomposites with low MWCNTs contents (0.1 wt. %) get better MWCNTs dispersion than higher MWCNT loading. Comparing with PET, nucleated PET nanocomposite with 0.1% MWCNT loading shows higher value of Lauritzen-Hoffman parameters U* and Kg evaluated using the differential isoconversional method. Crystallization regime transition temperature range shifts to higher temperature (208°C - 215°C) for nanocomposites. The presence of p-PET in addition of MWCNT, which act as good nucleating agent, enhanced the crystallization of PET through heterogeneous nucleation.

  7. PRIMARY STUDY ON BLENDS BASED ON THERMOTROPIC LIQUID CRYSTAL COPOLYESTER AND PET

    Institute of Scientific and Technical Information of China (English)

    WU Liheng; ZHANG Guoyao; YI Guozhen; LIU Dong

    1992-01-01

    The blend system composed of PET and thermotropic liquid crystal copolyester based on hydroxy benzoic acid, terephthalic acid, diacetyinaphthalene and PET was studied. The results indicated that LCP could play the role of crystal nuclei. The introduction of LCP decreased the melt viscosity of the system and fibrillous structure could be formed in favor conditions.

  8. Highly-stable monolithic femtosecond Yb-fiber laser system based on photonic crystal fibers

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

    2010-01-01

    of around 297 fs duration. Our laser shows exceptional stability. No Q-switched modelocking events were detected during 4-days long observation. An average fluctuation of only 7.85 · 10−4 over the mean output power was determined as a result of more than 6-hours long measurement. The laser is stable towards......A self-starting, passively stabilized, monolithic all polarizationmaintaining femtosecond Yb-fiber master oscillator / power amplifier with very high operational and environmental stability is demonstrated. The system is based on the use of two different photonic crystal fibers. One is used...... in the oscillator cavity for dispersion balancing and nonlinear optical limiting, and another one is used for low nonlinearity final pulse recompression. The chirped-pulse amplification and recompression of the 232-fs, 45-pJ/pulse oscillator output yields a final direct fiber-end delivery of 7.3-nJ energy pulses...

  9. Self-Powered Ultrabroadband Photodetector Monolithically Integrated on a PMN-PT Ferroelectric Single Crystal.

    Science.gov (United States)

    Fang, Huajing; Xu, Chao; Ding, Jie; Li, Qiang; Sun, Jia-Lin; Dai, Ji-Yan; Ren, Tian-Ling; Yan, Qingfeng

    2016-12-07

    Photodetectors capable of detecting two or more bands simultaneously with a single system have attracted extensive attentions because of their critical applications in image sensing, communication, and so on. Here, we demonstrate a self-powered ultrabroadband photodetector monolithically integrated on a 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-28PT) single crystal. By combining the optothermal and pyroelectric effect, the multifunctional PMN-28PT single crystal can response to a wide wavelength range from UV to terahertz (THz). At room temperature, the photodetector could generate a pyroelectric current under the intermittent illumination of incident light in absence of external bias. A systematic study of the photoresponse was investigated. The pyroelectric current shows an almost linear relationship to illumination intensity. Benefiting from the excellent pyroelectric property of PMN-28PT single crystal and the optimized device architecture, the device exhibited a dramatic improvement in operation frequency up to 3 kHz without any obvious degradation in sensitivity. Such a self-powered photodetector with ultrabroadband response may open a window for the novel application of ferroelectric materials in optoelectronics.

  10. Results of a combined monolithic crystal and an array of ASICs controlled SiPMs

    Energy Technology Data Exchange (ETDEWEB)

    Conde, P.; González, A.J., E-mail: agonzalez@i3m.upv.es; Hernández, L.; Bellido, P.; Iborra, A.; Crespo, E.; Moliner, L.; Rigla, J.P.; Rodríguez-Álvarez, M.J.; Sánchez, F.; Seimetz, M.; Soriano, A.; Vidal, L.F.; Benlloch, J.M.

    2014-01-11

    In this work we present the energy and spatial resolutions we have obtained for a γ-ray detector based on a monolithic LYSO crystal coupled to an array of 256 SiPMs. Two crystal configurations of the same trapezoidal shape have been tried. In one approach all surfaces were black painted but the exit one facing the photosensor array which was polished. The other approach included a retroreflector (RR) layer coupled to the entrance face of the crystal powering the amount of transmitted light to the photosensors. Two coupling media between the scintillator and the SiPM array were used, namely direct coupling by means of optical grease and coupling through an array of light guides. Since the same operational voltage was supplied to the entire array, it was needed to equalize their gains before feeding their signals to the Data Acquisition system. Such a job was performed by means of 4 scalable Application Specific Circuits (ASICs). An energy resolution of about 24.4% has been achieved for the direct coupling with the RR layer together with a spatial resolution of approximately 2.9 mm at the detector center. With the light guides coupling the effects of image compression at the edges are significantly minimized, but worsening the energy resolution to about 33.1% with a spatial resolution nearing 4 mm at the detector center.

  11. Monolithic integration of III-V nanowire with photonic crystal microcavity for vertical light emission.

    Science.gov (United States)

    Larrue, Alexandre; Wilhelm, Christophe; Vest, Gwenaelle; Combrié, Sylvain; de Rossi, Alfredo; Soci, Cesare

    2012-03-26

    A novel photonic structure formed by the monolithic integration of a vertical III-V nanowire on top of a L3 two-dimensional photonic crystal microcavity is proposed to enhance light emission from the nanowire. The impact on the nanowire spontaneous emission rate is evaluated by calculating the spontaneous emission factor β, and the material gain at threshold is used as a figure of merit of this vertical emitting nanolaser. An optimal design is identified for a GaAs nanowire geometry with r = 155 nm and L~1.1 μm, where minimum gain at threshold (gth~13×10³ cm⁻¹) and large spontaneous emission factor (β~0.3) are simultaneously achieved. Modification of the directivity of the L3 photonic crystal cavity via the band-folding principle is employed to further optimize the far-field radiation pattern and to increase the directivity of the device. These results lay the foundation for a new approach toward large-scale integration of vertical emitting nanolasers and may enable applications such as intra-chip optical interconnects.

  12. Single crystal Fe1-xGax thin films for monolithic microwave devices

    Science.gov (United States)

    Kuanr, Bijoy K.; Camley, R. E.; Celinski, Z.; McClure, Adam; Idzerda, Yves

    2014-05-01

    Modern, high frequency, microwave devices for communications technologies can be made with thin ferromagnetic films with narrow microwave resonance linewidths. Recently, there has been interest in magnetostrictive materials where the material constants can change substantially with stresses and applied magnetic fields. We report the development of single crystal thin (20 nm thick) magnetostrictive films of Fe1-xGax (x = 0.20 FeGa(A), 0.23 FeGa(B), 0.28 FeGa(C) on GaAs(001) substrates and on their use in prototype microwave devices. These Galfenol films have a narrower linewidth than any previously reported similar thin films. We fabricate and characterize novel microstrip-based monolithic microwave devices using Galfenol thin films as an active element. We find a number of important features: (1) There is a large absorption (up to 30 dB/cm) at the resonance frequency. (2) The linewidth of the device is narrow ˜1.5 GHz. (3) The saturation magnetization of the samples decreases with the increase in Ga contents. (4) The cubic anisotropy is close to zero (˜0.06 kOe for FeGa(A)) and becomes negative for higher concentration of Ga content in the samples, and (5) the damping increases with increase in Ga concentration.

  13. High resolution detectors based on continuous crystals and SiPMs for small animal PET

    Energy Technology Data Exchange (ETDEWEB)

    Cabello, J. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Barrillon, P. [Laboratoire de L' Accélérateur Linéaire (LAL), Orsay (France); Barrio, J. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Bisogni, M.G.; Del Guerra, A. [Dipartimento di Fisica “E. Fermi“, Università di Pisa and INFN Pisa, Pisa (Italy); Lacasta, C. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Rafecas, M. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); Departamento de Física Atómica, Nuclear y Molecular, Universitat de València, Valencia (Spain); Saikouk, H. [Laboratoire de Physique Nucléaire, Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Solaz, C.; Solevi, P. [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain); La Taille, C. de [Laboratoire de L' Accélérateur Linéaire (LAL), Orsay (France); Llosá, G., E-mail: gabriela.llosa@ific.uv.es [Instituto de Física Corpuscular, Universitat de València/CSIC, Valencia (Spain)

    2013-08-01

    Sensitivity and spatial resolution are the two main factors to maximize in emission imaging. The improvement of one factor deteriorates the other with pixelated crystals. In this work we combine SiPM matrices with monolithic crystals, using an accurate γ-ray interaction position determination algorithm that provides depth of interaction. Continuous crystals provide higher sensitivity than pixelated crystals, while an accurate interaction position determination does not degrade the spatial resolution. Monte Carlo simulations and experimental data show good agreement both demonstrating sub-millimetre intrinsic spatial resolution. A system consisting in two rotating detectors in coincidence is currently under operation already producing tomographic images.

  14. GPU-based optical propagation simulator of a laser-processed crystal block for the X'tal cube PET detector.

    Science.gov (United States)

    Ogata, Yuma; Ohnishi, Takashi; Moriya, Takahiro; Inadama, Naoko; Nishikido, Fumihiko; Yoshida, Eiji; Murayama, Hideo; Yamaya, Taiga; Haneishi, Hideaki

    2014-01-01

    The X'tal cube is a next-generation DOI detector for PET that we are developing to offer higher resolution and higher sensitivity than is available with present detectors. It is constructed from a cubic monolithic scintillation crystal and silicon photomultipliers which are coupled on various positions of the six surfaces of the cube. A laser-processing technique is applied to produce 3D optical boundaries composed of micro-cracks inside the monolithic scintillator crystal. The current configuration is based on an empirical trial of a laser-processed boundary. There is room to improve the spatial resolution by optimizing the setting of the laser-processed boundary. In fact, the laser-processing technique has high freedom in setting the parameters of the boundary such as size, pitch, and angle. Computer simulation can effectively optimize such parameters. In this study, to design optical characteristics properly for the laser-processed crystal, we developed a Monte Carlo simulator which can model arbitrary arrangements of laser-processed optical boundaries (LPBs). The optical characteristics of the LPBs were measured by use of a setup with a laser and a photo-diode, and then modeled in the simulator. The accuracy of the simulator was confirmed by comparison of position histograms obtained from the simulation and from experiments with a prototype detector composed of a cubic LYSO monolithic crystal with 6 × 6 × 6 segments and multi-pixel photon counters. Furthermore, the simulator was accelerated by parallel computing with general-purpose computing on a graphics processing unit. The calculation speed was about 400 times faster than that with a CPU.

  15. LOR-interleaving image reconstruction for PET imaging with fractional-crystal collimation

    Science.gov (United States)

    Li, Yusheng; Matej, Samuel; Karp, Joel S.; Metzler, Scott D.

    2015-01-01

    Positron emission tomography (PET) has become an important modality in medical and molecular imaging. However, in most PET applications, the resolution is still mainly limited by the physical crystal sizes or the detector’s intrinsic spatial resolution. To achieve images with better spatial resolution in a central region of interest (ROI), we have previously proposed using collimation in PET scanners. The collimator is designed to partially mask detector crystals to detect lines of response (LORs) within fractional crystals. A sequence of collimator-encoded LORs is measured with different collimation configurations. This novel collimated scanner geometry makes the reconstruction problem challenging, as both detector and collimator effects need to be modeled to reconstruct high-resolution images from collimated LORs. In this paper, we present a LOR-interleaving (LORI) algorithm, which incorporates these effects and has the advantage of reusing existing reconstruction software, to reconstruct high-resolution images for PET with fractional-crystal collimation. We also develop a 3D ray-tracing model incorporating both the collimator and crystal penetration for simulations and reconstructions of the collimated PET. By registering the collimator-encoded LORs with the collimator configurations, high-resolution LORs are restored based on the modeled transfer matrices using the non-negative least-squares method and EM algorithm. The resolution-enhanced images are then reconstructed from the high-resolution LORs using the MLEM or OSEM algorithm. For validation, we applied the LORI method to a small-animal PET scanner, A-PET, with a specially designed collimator. We demonstrate through simulated reconstructions with a hot-rod phantom and MOBY phantom that the LORI reconstructions can substantially improve spatial resolution and quantification compared to the uncollimated reconstructions. The LORI algorithm is crucial to improve overall image quality of collimated PET, which

  16. Monolithic LaBr₃:Ce crystals on silicon photomultiplier arrays for time-of-flight positron emission tomography.

    Science.gov (United States)

    Seifert, Stefan; van Dam, Herman T; Huizenga, Jan; Vinke, Ruud; Dendooven, Peter; Löhner, Herbert; Schaart, Dennis R

    2012-04-21

    Positron emission tomography detectors based on monolithic scintillation crystals exhibit good spatial and energy resolution, intrinsically provide depth-of-interaction information, have high γ-photon capture efficiency, and may reduce the manufacturing costs compared to pixelated crystal arrays. Here, we present the characterization of a detector consisting of a 18.0 mm×16.2 mm×10.0 mm monolithic LaBr₃:5%Ce scintillator directly coupled to a 4×4 array of silicon photomultipliers. An energy resolution of 6.4% full-width-at-half-maximum (FWHM) was obtained. The point-spread-function (PSF) was determined for different regions of the detector. The full-width-at-half-maximum (FWHM) of the PSF was measured to be <1.5 mm at the center of the detector and <1.7 mm averaged over the entire crystal. Both values are not corrected for the ~0.6 mm FWHM test beam diameter. Furthermore, the influence of edge effects was investigated. We found that near the edges of the detector the spatial resolution degrades to 2.2 mm (FWHM), and a bias in the position estimates, up to 1.5 mm, was observed. Moreover, the coincidence resolving time for two identical detectors in coincidence was measured to be as small as ~198 ps FWHM.

  17. Characterization studies of Silicon Photomultipliers and crystals matrices for a novel time of flight PET detector

    CERN Document Server

    Auffray, Etiennette; Cortinovis, Daniele; Doroud, Katayoun; Garutti, Erika; Lecoq, Paul; Liu, Zheng; Martinez, Rosana; Paganoni, Marco; Pizzichemi, Marco; Silenzi, Alessandro; Xu, Chen; Zvolský, Milan

    2015-01-01

    This paper describes the characterization of crystal matrices and silicon photomultiplier arrays for a novel Positron Emission Tomography (PET) detector, namely the external plate of the EndoTOFPET-US system. The EndoTOFPET-US collaboration aims to integrate Time-Of-Flight PET with ultrasound endoscopy in a novel multimodal device, capable to support the development of new biomarkers for prostate and pancreatic tumors. The detector consists in two parts: a PET head mounted on an ultrasound probe and an external PET plate. The challenging goal of 1 mm spatial resolution for the PET image requires a detector with small crystal size, and therefore high channel density: 4096 LYSO crystals individually readout by Silicon Photomultipliers (SiPM) make up the external plate. The quality and properties of these components must be assessed before the assembly. The dark count rate, gain, breakdown voltage and correlated noise of the SiPMs are measured, while the LYSO crystals are evaluated in terms of light yield and en...

  18. Paul Lecoq assembles a read head made with special crystals for a PET (positron emission tomography) scanner. He is the initiator of the Crystal Clear collaboration, which aims to transfer crystals developed at CERN to applications in medical imaging.

    CERN Multimedia

    Maximilien Brice

    2004-01-01

    Paul Lecoq assembles a read head made with special crystals for a PET (positron emission tomography) scanner. He is the initiator of the Crystal Clear collaboration, which aims to transfer crystals developed at CERN to applications in medical imaging.

  19. Two-axis MEMS scanner with transfer-printed high-reflectivity, broadband monolithic silicon photonic crystal mirrors.

    Science.gov (United States)

    Jeong, Jae-Woong; Park, Bryan; Keum, Hohyun; Kim, Seok; Rogers, John A; Solgaard, Olav

    2013-06-03

    We present a two-axis electrostatic MEMS scanner with high-reflectivity monolithic single-crystal-silicon photonic crystal (PC) mirrors suitable for applications in harsh environments. The reflective surfaces of the MEMS scanner are transfer-printed PC mirrors with low polarization dependence, low angular dependence, and reflectivity over 85% in the wavelength range of 1490nm~1505nm and above 90% over the wavelength band of 1550~1570nm. In static mode, the scanner has total scan range of 10.2° on one rotation axis and 7.8° on the other. Dynamic operation on resonance increase the scan range to 21° at 608Hz around the outer rotation axis and 9.5° at 1.73kHz about the inner rotation axis.

  20. Crystal timing offset calibration method for time of flight PET scanners

    Science.gov (United States)

    Ye, Jinghan; Song, Xiyun

    2016-03-01

    In time-of-flight (TOF) positron emission tomography (PET), precise calibration of the timing offset of each crystal of a PET scanner is essential. Conventionally this calibration requires a specially designed tool just for this purpose. In this study a method that uses a planar source to measure the crystal timing offsets (CTO) is developed. The method uses list mode acquisitions of a planar source placed at multiple orientations inside the PET scanner field-of-view (FOV). The placement of the planar source in each acquisition is automatically figured out from the measured data, so that a fixture for exactly placing the source is not required. The expected coincidence time difference for each detected list mode event can be found from the planar source placement and the detector geometry. A deviation of the measured time difference from the expected one is due to CTO of the two crystals. The least squared solution of the CTO is found iteratively using the list mode events. The effectiveness of the crystal timing calibration method is evidenced using phantom images generated by placing back each list mode event into the image space with the timing offset applied to each event. The zigzagged outlines of the phantoms in the images become smooth after the crystal timing calibration is applied. In conclusion, a crystal timing calibration method is developed. The method uses multiple list mode acquisitions of a planar source to find the least squared solution of crystal timing offsets.

  1. 叉指结构在单片晶体滤波器中的应用%Application of interdigital structure in monolithic crystal filters

    Institute of Scientific and Technical Information of China (English)

    孙峰; 张忠友

    2013-01-01

    剖析了一种复合型宽带单片式晶体滤波器.从单片晶体滤波器和叉指换能器的原理出发对该滤波器进行了理论分析,然后使用仿真软件模拟了叉指结构对单片式晶体滤波器的影响.最后通过实验证明了插指结构对晶体滤波器具有调整矩形系数,增加带外抑制和频率微调的作用.%A composite broadband monolithic crystal filter is analyzed. The paper begins with a description of the principle of monolithic crystal filters and interdigital transducer, followed by a therotecial analysis of the filter. A simulation software is used to simulate the impact of interdigital structure on monolithic crystal filters. Finally, the experiment shows that the interpola-tion structure improves the rectangular coefficient and increases out-band rejection and frequency fine tuning for the monolithic crystal filter.

  2. A novel gamma-ray detector with submillimeter resolutions using a monolithic MPPC array with pixelized Ce:LYSO and Ce:GGAG crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kato, T., E-mail: katou.frme.8180@asagi.waseda.jp [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Kataoka, J.; Nakamori, T.; Miura, T.; Matsuda, H.; Kishimoto, A. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Sato, K.; Ishikawa, Y.; Yamamura, K.; Nakamura, S.; Kawabata, N. [Solid State Division, Hamamatsu Photonics K. K., 1126-1, Ichino-cho, Hamamatsu, Shizuoka (Japan); Ikeda, H. [ISAS/JAXA, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara-shi, Kanagawa (Japan); Yamamoto, S. [Kobe City College of Technology, 8-3, Gakuenhigashimati, Nishi-ku, Kobe-shi, Hyougo 651-2194 (Japan); Kamada, K. [Materials Research Laboratory, Furukawa Co., Ltd., 1-25-13, Kannondai, Tsukuba, Ibaraki 305-0856 (Japan)

    2013-01-21

    We have developed a large-area monolithic Multi-Pixel Photon Counter (MPPC) array consisting of 4×4 channels with a three-side buttable package. Each channel has a photosensitive area of 3×3 mm{sup 2} and 3600 Geiger mode avalanche photodiodes (APDs). For typical operational gain of 7.5×10{sup 5} at +20 °C, gain fluctuation over the entire MPPC device is only ±5.6%, and dark count rates (as measured at the 1 p.e. level) amount to ≤400kcps per channel. We first fabricated a gamma-ray camera consisting of the MPPC array with one-to-one coupling to a Ce-doped (Lu,Y){sub 2}(SiO{sub 4})O (Ce:LYSO) crystal array (4×4 array of 3×3×10 mm{sup 3} crystals). Energy and time resolutions of 11.5±0.5% (FWHM at 662 keV) and 493±22ps were obtained, respectively. When using the charge division resistor network, which compiles signals into four position-encoded analog outputs, the ultimate positional resolution is estimated as 0.19 mm in both X and Y directions, while energy resolution of 10.2±0.4% (FWHM) was obtained. Finally, we fabricated submillimeter Ce:LYSO and Ce-doped Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12} (Ce:GGAG) scintillator matrices each consisting of 1.0×1.0, 0.7×0.7 and 0.5×0.5 mm{sup 2} pixels, to further improve the spatial resolution. In all types of Ce:LYSO and Ce:GGAG matrices, each crystal was clearly resolved in the position histograms when irradiated by a {sup 137}Cs source. The energy resolutions for 662 keV gamma-rays for each Ce:LYSO and Ce:GGAG scintillator matrix were ≤14.3%. These results suggest excellent potential for its use as a high spatial medical imaging device, particularly in positron emission tomography (PET). -- Highlights: ► We developed a newly designed large-area monolithic MPPC array. ► We obtained fine gain uniformity, and good energy and time resolutions when coupled to the LYSO scintillator. ► We fabricated gamma-ray camera consisting of the MPPC array and submillimeter pixelized LYSO and GGAG scintillators. ► In

  3. A novel gamma-ray detector with submillimeter resolutions using a monolithic MPPC array with pixelized Ce:LYSO and Ce:GGAG crystals

    Science.gov (United States)

    Kato, T.; Kataoka, J.; Nakamori, T.; Miura, T.; Matsuda, H.; Kishimoto, A.; Sato, K.; Ishikawa, Y.; Yamamura, K.; Nakamura, S.; Kawabata, N.; Ikeda, H.; Yamamoto, S.; Kamada, K.

    2013-01-01

    We have developed a large-area monolithic Multi-Pixel Photon Counter (MPPC) array consisting of 4×4 channels with a three-side buttable package. Each channel has a photosensitive area of 3×3 mm2 and 3600 Geiger mode avalanche photodiodes (APDs). For typical operational gain of 7.5×105 at +20 °C, gain fluctuation over the entire MPPC device is only ±5.6%, and dark count rates (as measured at the 1 p.e. level) amount to ≤400 kcps per channel. We first fabricated a gamma-ray camera consisting of the MPPC array with one-to-one coupling to a Ce-doped (Lu, Y)2(SiO4)O (Ce:LYSO) crystal array (4×4 array of 3×3×10 mm3 crystals). Energy and time resolutions of 11.5±0.5% (FWHM at 662 keV) and 493±22 ps were obtained, respectively. When using the charge division resistor network, which compiles signals into four position-encoded analog outputs, the ultimate positional resolution is estimated as 0.19 mm in both X and Y directions, while energy resolution of 10.2±0.4% (FWHM) was obtained. Finally, we fabricated submillimeter Ce:LYSO and Ce-doped Gd3Ga3Al2O12 (Ce:GGAG) scintillator matrices each consisting of 1.0×1.0, 0.7×0.7 and 0.5×0.5 mm2 pixels, to further improve the spatial resolution. In all types of Ce:LYSO and Ce:GGAG matrices, each crystal was clearly resolved in the position histograms when irradiated by a 137Cs source. The energy resolutions for 662 keV gamma-rays for each Ce:LYSO and Ce:GGAG scintillator matrix were ≤14.3%. These results suggest excellent potential for its use as a high spatial medical imaging device, particularly in positron emission tomography (PET).

  4. Simulation study of PET detector limitations using continuous crystals

    Science.gov (United States)

    Cabello, Jorge; Etxebeste, Ane; Llosá, Gabriela; Ziegler, Sibylle I.

    2015-05-01

    Continuous crystals can potentially obtain better intrinsic detector spatial resolution compared to pixelated crystals, additionally providing depth of interaction (DoI) information from the light distribution. To achieve high performance sophisticated interaction position estimation algorithms are required. There are a number of algorithms in the literature applied to different crystal dimensions and different photodetectors. However, the different crystal properties and photodetector array geometries have an impact on the algorithm performance. In this work we analysed, through Monte Carlo simulations, different combinations of realistic crystals and photodetector parameters to better understand their influence on the interaction position estimation accuracy, with special emphasis on the DoI. We used an interaction position estimation based on an analytical model for the present work. Different photodetector granulation schemes were investigated. The impact of the number of crystal faces readout by photodetectors was studied by simulating scenarios with one and two photodetectors. In addition, crystals with different levels of reflection and aspect ratios (AR) were analysed. Results showed that the impact of photodetector granularity is mainly shown near the edges and specially in the corners of the crystal. The resulting intrinsic spatial resolution near the centre with a 12 × 12 × 10 mm3 LYSO crystal was 0.7-0.9 mm, while the average spatial resolution calculated on the entire crystal was 0.77 ± 0.18 mm for all the simulated geometries with one and two photodetectors. Having front and back photodetectors reduced the DoI bias (Euclidean distance between estimated DoI and real DoI) and improved the transversal resolution near the corners. In scenarios with one photodetector, small AR resulted in DoI inaccuracies for absorbed events at the entrance of the crystal. These inaccuracies were slightly reduced either by increasing the AR or reducing the amount of

  5. PET

    DEFF Research Database (Denmark)

    Mariager, Rasmus Mølgaard; Schmidt, Regin; Heiberg, Morten Rievers

    PET handler om den hemmelige tjenestes arbejde under den kolde krig 1945-1989. Her fortæller Regin Schmidt, Rasmus Mariager og Morten Heiberg om de mest dramatiske og interessante sager fra PET's arkiv. PET er på flere måder en udemokratisk institution, der er sat til at vogte over demokratiet....... Dens virksomhed er skjult for offentligheden, den overvåger borgernes aktiviteter, og den registrerer følsomme personoplysninger. Historien om PET rejser spørgsmålet om, hvad man skal gøre, når befolkningen i et demokrati er kritisk indstillet over for overvågningen af lovlige politiske aktiviteter......, mens myndighederne mener, at det er nødvendigt for at beskytte demokratiet. PET er på en gang en fortælling om konkrete aktioner og begivenheder i PET's arbejde og et stykke Danmarkshistorie. Det handler om overvågning, spioner, politisk ekstremisme og international terrorisme.  ...

  6. Molecular Weight and Crystallization Temperature Effects on Poly(ethylene terephthalate (PET Homopolymers, an Isothermal Crystallization Analysis

    Directory of Open Access Journals (Sweden)

    Leonardo A. Baldenegro-Perez

    2014-02-01

    Full Text Available The isothermal crystallization of poly(ethylene terephthalate (PET homopolymers with different molecular weight was studied in a wide temperature range (140–230 °C using different experimental techniques. Three different morphological regions, labeled r1, r2 and r3, were distinguished as a function of crystallization temperature (Tc. In r1 (low Tc crystallized samples were characterized by a low crystalline degree with a small spherulite texture containing thin crystals. In r2 (intermediate Tc samples showed medium size spherulites composed of two distinct crystalline families (thin and thick crystals. In this temperature range, the crystallization exhibited a maximum value and it was associated with a high content of secondary crystals. In r3 (high Tc, samples presented considerable amorphous zones and regions consisting of oversized spherulites containing only thick crystals. Time-resolved wide-angle X-ray diffraction measurements, using synchrotron radiation, indicated a rapid evolution of the crystalline degree within the second region, in contrast with the quite slow evolution observed in the third region. On the other hand, by small-angle X-ray scattering (SAXS and time-resolved SAXS experiment, it was found that the long period (L as well as the lamellar thickness (lc increase as a function of Tc, corroborating the formation of the thickest crystals in the third region. From all these observations, a morphological model was proposed for each region.

  7. Development of a Single Detector Ring Micro Crystal Element Scanner: QuickPET II

    Directory of Open Access Journals (Sweden)

    Robert S. Miyaoka

    2005-04-01

    Full Text Available This article describes a single ring version of the micro crystal element scanner (MiCES and investigation of its spatial resolution imaging characteristics for mouse positron emission tomography (PET imaging. This single ring version of the MiCES system, referred to as QuickPET II, consists of 18 MiCE detector modules mounted as a single ring in a vertical gantry. The system has a 5.76-cm transverse field of view and a 1.98-cm axial field of view. In addition to the scanner and data acquisition system, we have developed an iterative reconstruction that includes a model of the system's detector response function. Evaluation images of line sources and mice have been acquired. Using filtered backprojection, the resolution for a reconstructed line source has been measured at 1.2 mm full width at half maximum. F-18-2-fluoro-2-deoxyglucose mouse PET images are provided. The result shows that QuickPET II has the imaging characteristics to support high-resolution, static mouse PET studies using 18-F labeled compounds.

  8. Development of a single detector ring micro crystal element scanner: QuickPET II.

    Science.gov (United States)

    Miyaoka, Robert S; Janes, Marie L; Lee, Kisung; Park, Byungki; Kinahan, Paul E; Lewellen, Tom K

    2005-01-01

    This article describes a single ring version of the micro crystal element scanner (MiCES) and investigation of its spatial resolution imaging characteristics for mouse positron emission tomography (PET) imaging. This single ring version of the MiCES system, referred to as QuickPET II, consists of 18 MiCE detector modules mounted as a single ring in a vertical gantry. The system has a 5.76-cm transverse field of view and a 1.98-cm axial field of view. In addition to the scanner and data acquisition system, we have developed an iterative reconstruction that includes a model of the system's detector response function. Evaluation images of line sources and mice have been acquired. Using filtered backprojection, the resolution for a reconstructed line source has been measured at 1.2 mm full width at half maximum. F-18-2-fluoro-2-deoxyglucose mouse PET images are provided. The result shows that QuickPET II has the imaging characteristics to support high-resolution, static mouse PET studies using 18-F labeled compounds.

  9. FDG gamma camera PET equipped with one inch crystal and XCT. Assessment of myocardial viability

    Energy Technology Data Exchange (ETDEWEB)

    Beheshti, M. [Dept. of Nuclear Medicine, Medical Univ., General Hospital of Vienna (Austria); Dept. of Nuclear Medicine and Endocrinology, PET CT Centre, St. Vincent' s Hospital, Linz (Austria); Khorsand, A.; Graf, S. [Dept. of Cardiology, Medical Univ., General Hospital of Vienna (Austria); Dobrozemsky, G. [Dept. of Nuclear Medicine, Medical Univ. of Innsbruck (Austria); Oezer, S.; Kletter, K.; Dudczak, R. [Dept. of Nuclear Medicine, Medical Univ., General Hospital of Vienna (Austria); Pirich, C. [Dept. of Nuclear Medicine und Endocrinology, Paracelsus Private Medical Univ., SALK, Salzburg (Austria)

    2006-07-01

    Metabolic imaging with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) is actually considered as the best method to detect and quantitatively assess myocordial tissue viability. The aim of this study was to investigate the accuracy of FDG gamma camera positron emission tomography (GCPET) imaging equipped with one inch NaI crystals in comparison to FDG dedicated PET (dPET) imaging as a ''gold standard'' in phantom and clinical studies. Patients, methods: nineteen patients with coronary artery disease (CAD) underwent both imaging modalities. Phantom and clinical GCPET imaging were performed with a dual-headed, coincidence based gamma camera equipped with 1 inch thick NaI crystals and an X-ray tube (XCT) for attenuation correction (AC), as well as with a dedicated PET scanner with AC. {sup 99m}Tc tetrofosmin single-photon emission tomography (SPET) studies were performed for assessment of myocardial perfusion, with AC. Results: phantom studies showed a significant relation in segmental activity between FDG imaging with AC using GCPET and dPET (r = 0.91, p < 0.001). In clinical studies with AC correlation coefficients of mean segmental FDG uptake and regional defect size were r = 0.87 (p < 0.0001) and r = 0.83 (p < 0.0001), respectively. In regional analysis close agreement was even found in the most attenuated regions of the heart if AC was used in GCPET imaging. The overall agreement for detection of viable myocardium was 81% between FDG-dPET (AC) and FDG-GCPET (AC) and 74% between FDG-dPET (AC) and FDG-GCPET (NC). Conclusions: suggests that the assessment of myocardial metabolism by means of FDG is feasible with a coincidence based gamma camera equipped with 1 inch thick NaI crystal if AC is performed. The results reveal a close concordance and agreement between FDG-dPET (AC) and FDG-GCPET (AC) as compared to FDG-GCPET (NC). (orig.)

  10. A miniaturized, eye-conformable, and long-term reliable retinal prosthesis using monolithic fabrication of liquid crystal polymer (LCP).

    Science.gov (United States)

    Jeong, Joonsoo; Bae, So Hyun; Min, Kyou Sik; Seo, Jong-Mo; Chung, Hum; Kim, Sung June

    2015-03-01

    A novel retinal prosthetic device was developed using biocompatible liquid crystal polymer (LCP) to address the problems associated with conventional metal- and polymer-based devices: the hermetic metal package is bulky, heavy, and labor-intensive, whereas a thin, flexible, and MEMS-compatible polymer-based system is not durable enough for chronic implantation. Exploiting the advantageous properties of LCP such as a low moisture absorption rate, thermobonding, and thermoforming, we fabricate a small, light-weight, long-term reliable retinal prosthesis that can be conformally attached on the eye-surface. A LCP fabrication process using monolithic integration and conformal deformation was established enabling miniaturization and a batch manufacturing process as well as eliminating the need for feed-through technology. The functionality of the fabricated device was tested through wireless operation in saline solution. Its efficacy and implantation stability were verified through in vivo animal tests by measuring the cortical potential and monitoring implanted dummy devices for more than a year, respectively.

  11. Sensitivity recovery for the AX-PET prototype using inter-crystal scattering events

    CERN Document Server

    Gillam, John E; Oliver, Josep F; Casella, Chiara; Heller, Matthieu; Joram, Christian; Rafecas, Magdalena

    2014-01-01

    The development of novel detection devices and systems such as the AX-positron emission tomography (PET) demonstrator often introduce or increase the measurement of atypical coincidence events such as inter-crystal scattering (ICS). In more standard systems, ICS events often go undetected and the small measured fraction may be ignored. As the measured quantity of such events in the data increases, so too does the importance of considering them during image reconstruction. Generally, treatment of ICS events will attempt to determine which of the possible candidate lines of response (LoRs) correctly determine the annihilation photon trajectory. However, methods of assessment often have low success rates or are computationally demanding. In this investigation alternative approaches are considered. Experimental data was taken using the AX-PET prototype and a NEMA phantom. Three methods of ICS treatment were assessed-each of which considered all possible candidate LoRs during image reconstruction. Maximum likeliho...

  12. Crystal Clear - New crystals for LHC experiments help to improve PET scanners Exhibition LEPFest 2000

    CERN Multimedia

    2000-01-01

    Better resolution through smaller crystals Better images through higher light yieldHigh efficiency, stability and gain by using avalanche photodiodes and low noise electronics Reduced cost of crystals (1/10) through mass production

  13. The effect of Pglass state on the non-isothermal cold and melt crystallization processes of PET matrix

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Huichao [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Ma, Jinghong, E-mail: mjh68@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Gong, Jinghua [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Xu, Jian, E-mail: jxu@iccas.ac.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Beijing National Laboratory for Molecular Sciences, Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-08-10

    Highlights: • Pglass is an inorganic polymer with low T{sub g} and mutable viscosity. • Kinetics models and activation energy can be used to analyze the process. • Pglass can play different effect on the crystallization process of PET. - Abstract: The physical state of phosphate glass (Pglass) has an influence on the non-isothermal crystallization behaviors of PET matrix in the PET/Pglass blends, which has been investigated via heating the glassy state and cooling the melt state of the blends at various scanning rates, respectively, by means of differential scanning calorimetry (DSC) technique. The kinetics models based on the Avrami and Mo equations were used to analyze the non-isothermal crystallization process. Furthermore, the activation energy of non-isothermal crystallization, according to Kissinger theory for heating process and Friedman theory for cooling process, has been evaluated. The results showed that the Pglass accelerated the non-isothermal cold crystallization rate of PET matrix due to its nucleation effect. In contrast, for the non-isothermal melt crystallization, the Pglass hindered the crystallization process due to its large melt viscosity.

  14. Time resolution deterioration with increasing crystal length in a TOF-PET system

    CERN Document Server

    Gundacker, S; Auffray, E; Jarron, P; Meyer, T; Lecoq, P

    2014-01-01

    Highest time resolution in scintillator based detectors is becoming more and more important. In medical detector physics L(Y)SO scintillators are commonly used for time of flight positron emission tomography (TOF-PET). Coincidence time resolutions (CTRs) smaller than 100 ps FWHM are desirable in order to improve the image signal to noise ratio and thus give benefit to the patient by shorter scanning times. Also in high energy physics there is the demand to improve the timing capabilities of calorimeters down to 10 ps. To achieve these goals it is important to study the whole chain, i.e. the high energy particle interaction in the crystal, the scintillation process itself, the scintillation light transfer in the crystal, the photodetector and the electronics. Time resolution measurements for a PET like system are performed with the time-over-threshold method in a coincidence setup utilizing the ultra-fast amplifier-discriminator NINO. With 2×2×3 mm3 LSO:Ce codoped 0.4%Ca crystals coupled to commercially avai...

  15. Position algorithm for monolithic scintillation crystals based on charge projection readout

    Science.gov (United States)

    Pani, R.; Bettiol, M.; Preziosi, E.; Cinti, M. N.; Borrazzo, C.; Pellegrini, R.; Di Castro, E.; Fabbri, A.

    2016-01-01

    Nuclear medicine imaging devices commonly use multi-element photo detection systems, composed of an array of N × N elements, each one providing an individual signal. Many strategies have been developed to reduce the number of readout channels, one of the main approaches is the Rows and Columns (R/C) projection logic. In this paper we proposed a modified version of Raised To the Power (RTP) algorithm adapted to R/C logic. In order to validate its efficiency a linear scanning irradiation on two 49× 49 mm2 LaBr3:Ce (0.5%) crystals with different thickness (4 mm and 10 mm) was carried out. Imaging performance analysis was made in terms of position linearity, Field-of-View (FoV) enlargement and spatial resolution. Imaging results from Anger Logic, RTP algorithm based on single element readout and RTP algorithm based on R/C readout were compared. A notable advantage of using RTP algorithms instead of Anger Logic was found: the FoV widens from about 30% to more than 70% of the detector area whereas the spatial resolution is highly improved, especially for off-center interactions, both for 4 mm-thick and 10 mm-thick crystals. Furthermore, imaging performance with the R/C readout is just slightly different from the single element one (FoV reduction less than 7% and SR worsening less than 10%). The R/C adapted RTP algorithm opens doors to high imaging performance with a substantial reduction of complexity and cost in the readout electronics.

  16. MORPHOLOGICAL STUDIES OF PET FILMS WITH DIFFERENT CRYSTALLIZATION RATE IN DRAWING PROCESSES

    Institute of Scientific and Technical Information of China (English)

    XU Mao; ZHU Lilan; GUAN Jiayu

    1984-01-01

    Morphological changes during stretching of two PET samples (S and T) with different crystallization rate have been studied by means of SALS, solvent etching and polarizing microscope techniques. Results show that under the same drawing conditions larger and more perfect rod-like and spherulitic superstructures were formed more easily in the sample with higher crystallization rate (sample S). The amount of less compact regions which may be easily attacked by the vapor of allyl amine decreases more rapidly in sample S than in sample T during stretching, and these regions are more randomly distributed in sample T especially at low elongations. The difference of the two samples in morphological changes is coincident with their difference in tensile behavior.

  17. A technique for measuring the quality of an elliptically bent pentaerythritol [PET(002)] crystal.

    Science.gov (United States)

    Haugh, M J; Jacoby, K D; Barrios, M A; Thorn, D; Emig, J A; Schneider, M B

    2016-11-01

    We present a technique for determining the X-ray spectral quality from each region of an elliptically curved PET(002) crystal. The investigative technique utilizes the shape of the crystal rocking curve which changes significantly as the radius of curvature changes. This unique quality information enables the spectroscopist to verify where in the spectral range that the spectrometer performance is satisfactory and where there are regions that would show spectral distortion. A collection of rocking curve measurements for elliptically curved PET(002) has been built up in our X-ray laboratory. The multi-lamellar model from the XOP software has been used as a guide and corrections were applied to the model based upon measurements. But, the measurement of RI at small radius of curvature shows an anomalous behavior; the multi-lamellar model fails to show this behavior. The effect of this anomalous RI behavior on an X-ray spectrometer calibration is calculated. It is compared to the multi-lamellar model calculation which is completely inadequate for predicting RI for this range of curvature and spectral energies.

  18. A technique for measuring the quality of an elliptically bent pentaerythritol [PET(002)] crystal

    Science.gov (United States)

    Haugh, M. J.; Jacoby, K. D.; Barrios, M. A.; Thorn, D.; Emig, J. A.; Schneider, M. B.

    2016-11-01

    We present a technique for determining the X-ray spectral quality from each region of an elliptically curved PET(002) crystal. The investigative technique utilizes the shape of the crystal rocking curve which changes significantly as the radius of curvature changes. This unique quality information enables the spectroscopist to verify where in the spectral range that the spectrometer performance is satisfactory and where there are regions that would show spectral distortion. A collection of rocking curve measurements for elliptically curved PET(002) has been built up in our X-ray laboratory. The multi-lamellar model from the XOP software has been used as a guide and corrections were applied to the model based upon measurements. But, the measurement of RI at small radius of curvature shows an anomalous behavior; the multi-lamellar model fails to show this behavior. The effect of this anomalous RI behavior on an X-ray spectrometer calibration is calculated. It is compared to the multi-lamellar model calculation which is completely inadequate for predicting RI for this range of curvature and spectral energies.

  19. Characterization of stacked-crystal PET detector designs for measurement of both TOF and DOI

    Science.gov (United States)

    Schmall, Jeffrey P.; Surti, Suleman; Karp, Joel S.

    2015-05-01

    A PET detector with good timing resolution and two-level depth-of-interaction (DOI) discrimination can be constructed using a single-ended readout of scintillator stacks of Lanthanum Bromide (LaBr3), with various Cerium dopant concentrations, including pure Cerium Bromide (CeBr3). The stacked crystal geometry creates a unique signal shape for interactions occurring in each layer, which can be used to identify the DOI, while retaining the inherently good timing properties of LaBr3 and CeBr3. In this work, single pixel elements are used to optimize the choice of scintillator, coupling of layers, and type of photodetector, evaluating the performance using a fast, single-channel photomultiplier tube (PMT) and a single 4 × 4 mm2 silicon photomultiplier (SiPM). We also introduce a method to quantify and evaluate the DOI discrimination accuracy. From signal shape measurements using fast waveform sampling, we found that in addition to differences in signal rise times, between crystal layers, there were also differences in the signal fall times. A DOI accuracy of 98% was achieved using our classification method for a stacked crystal pair, consisting of a 15 mm long LaBr3(Ce:20%) crystal on top of a 15 mm long CeBr3 crystal, readout using a PMT. A DOI accuracy of 95% was measured with a stack of two, identical, 12 mm long, CeBr3 crystals. The DOI accuracy of this crystal pair was reduced to 91% when using a SiPM for readout. For the stack of two, 12 mm long, CeBr3 crystals, a coincidence timing resolution (average of timing results from the top and bottom layer) of 199 ps was measured using a PMT, and this was improved to 153 ps when using a SiPM. These results show that with stacked LaBr3/CeBr3 scintillators and fast waveform sampling nearly perfect DOI accuracy can be achieved with excellent timing resolution—timing resolution that is only minimally degraded compared to results from a single CeBr3 crystal of comparable length to the stacked crystals. The

  20. Sensitivity recovery for the AX-PET prototype using inter-crystal scattering events.

    Science.gov (United States)

    Gillam, John E; Solevi, Paola; Oliver, Josep F; Casella, Chiara; Heller, Matthieu; Joram, Christian; Rafecas, Magdalena

    2014-08-07

    The development of novel detection devices and systems such as the AX-positron emission tomography (PET) demonstrator often introduce or increase the measurement of atypical coincidence events such as inter-crystal scattering (ICS). In more standard systems, ICS events often go undetected and the small measured fraction may be ignored. As the measured quantity of such events in the data increases, so too does the importance of considering them during image reconstruction. Generally, treatment of ICS events will attempt to determine which of the possible candidate lines of response (LoRs) correctly determine the annihilation photon trajectory. However, methods of assessment often have low success rates or are computationally demanding. In this investigation alternative approaches are considered. Experimental data was taken using the AX-PET prototype and a NEMA phantom. Three methods of ICS treatment were assessed--each of which considered all possible candidate LoRs during image reconstruction. Maximum likelihood expectation maximization was used in conjunction with both standard (line-like) and novel (V-like in this investigation) detection responses modeled within the system matrix. The investigation assumed that no information other than interaction locations was available to distinguish between candidates, yet the methods assessed all provided means by which such information could be included. In all cases it was shown that the signal to noise ratio is increased using ICS events. However, only one method, which used full modeling of the ICS response in the system matrix--the V-like model--provided enhancement in all figures of merit assessed in this investigation. Finally, the optimal method of ICS incorporation was demonstrated using data from two small animals measured using the AX-PET demonstrator.

  1. Spatial distortion correction and crystal identification for MRI-compatible position-sensitive avalanche photodiode-based PET scanners.

    Science.gov (United States)

    Chaudhari, Abhijit J; Joshi, Anand A; Wu, Yibao; Leahy, Richard M; Cherry, Simon R; Badawi, Ramsey D

    2009-06-01

    Position-sensitive avalanche photodiodes (PSAPDs) are gaining widespread acceptance in modern PET scanner designs, and owing to their relative insensitivity to magnetic fields, especially in those that are MRI-compatible. Flood histograms in PET scanners are used to determine the crystal of annihilation photon interaction and hence, for detector characterization and routine quality control. For PET detectors that use PSAPDs, flood histograms show a characteristic pincushion distortion when Anger logic is used for event positioning. A small rotation in the flood histogram is also observed when the detectors are placed in a magnetic field. We first present a general purpose automatic method for spatial distortion correction for flood histograms of PSAPD-based PET detectors when placed both inside and outside a MRI scanner. Analytical formulae derived for this scheme are based on a hybrid approach that combines desirable properties from two existing event positioning schemes. The rotation of the flood histogram due to the magnetic field is determined iteratively and is accounted for in the scheme. We then provide implementation details of a method for crystal identification we have previously proposed and evaluate it for cases when the PET detectors are both outside and in a magnetic field. In this scheme, Fourier analysis is used to generate a lower-order spatial approximation of the distortion-corrected PSAPD flood histogram, which we call the 'template'. The template is then registered to the flood histogram using a diffeomorphic iterative intensity-based warping scheme. The calculated deformation field is then applied to the segmentation of the template to obtain a segmentation of the flood histogram. A manual correction tool is also developed for exceptional cases. We present a quantitative assessment of the proposed distortion correction scheme and crystal identification method against conventional methods. Our results indicate that our proposed methods lead to

  2. A DOI Detector With Crystal Scatter Identification Capability for High Sensitivity and High Spatial Resolution PET Imaging

    OpenAIRE

    2015-01-01

    A new phoswich detector is being developed at the Crump Institute, aiming to provide improvements in sensitivity, and spatial resolution for PET. The detector configuration is comprised of two layers of pixelated scintillator crystal arrays, a glass light guide and a light detector. The annihilation photon entrance (top) layer is a 48 × 48 array of 1.01 × 1.01 × 7 mm3 LYSO crystals. The bottom layer is a 32 × 32 array of 1.55 × 1.55 × 9 mm3 BGO crystals. A tapered, multiple-element glass ligh...

  3. Monolithic spectrometer

    Science.gov (United States)

    Rajic, Slobodan; Egert, Charles M.; Kahl, William K.; Snyder, Jr., William B.; Evans, III, Boyd M.; Marlar, Troy A.; Cunningham, Joseph P.

    1998-01-01

    A monolithic spectrometer is disclosed for use in spectroscopy. The spectrometer is a single body of translucent material with positioned surfaces for the transmission, reflection and spectral analysis of light rays.

  4. Imaging characterization of a new gamma ray detector based on CRY019 scintillation crystal for PET and SPECT applications

    Science.gov (United States)

    Polito, C.; Pani, R.; Trigila, C.; Cinti, M. N.; Fabbri, A.; Frantellizzi, V.; De Vincentis, G.; Pellegrini, R.; Pani, R.

    2017-02-01

    In the last 40 years, in the field of Molecular Medicine imaging there has been a huge growth in the employment and in the improvement of detectors for PET and SPECT applications in order to reach accurate diagnosis of the diseases. The most important feature required to these detectors is an high quality of images that is usually obtained benefitting from the development of a wide number of new scintillation crystals with high imaging performances. In this contest, features like high detection efficiency, short decay time, great spectral match with photodetectors, absence of afterglow and low costs are surely attractive. However, there are other factors playing an important role in the realization of high quality images such as energy and spatial resolutions, position linearity and contrast resolution. With the aim to realize an high performace gamma ray detector for PET and SPECT applications, this work is focused on the evaluation of the imaging characteristics of a recently developed scintillation crystal, CRY019.

  5. Simulation study optimizing the number of photodetection faces for the X'tal cube PET detector with separated crystal segments.

    Science.gov (United States)

    Matsumoto, Takahiro; Yamaya, Taiga; Yoshida, Eiji; Nishikido, Fumihiko; Inadama, Naoko; Murayama, Hideo; Suga, Mikio

    2014-01-01

    We are developing a novel PET detector with 3D isotropic resolution called a crystal (X'tal) cube. The X'tal cube detector consists of a crystal block all 6 surfaces of which are covered with silicon photomultipliers (SiPMs). We have developed a prototype detector with 3D isotropic 1 mm resolution. On the other hand, when the X'tal cubes are arranged to form a PET scanner, insensitive inter-detector gaps made by the SiPM arrays should not be too wide, or, better yet, they should be removed. Reduction of the number of SiPMs will also be reflected in the production costs. Therefore, reducing the number of faces to be connected to the SiPMs has become our top priority. In this study, we evaluated the effect of reducing the number of SiPMs on the positioning accuracy through numerical simulations. Simulations were performed with the X'tal cube, which was composed of a 6 × 6 × 6 array of Lu2x Gd2(1-x)SiO5:Ce crystal elements with dimensions of (3.0 mm)(3). Each surface of the crystal block was covered with a 4 × 4 array of SiPMs, each of which had a (3.0 mm)(2) active area. For material between crystal elements, we compared two: optical glue and an air gap. The air gap showed a better crystal identification performance than did the optical glue, although a good crystal identification performance was obtained even with optical glue for the 6-face photodetection. In conclusion, the number of photodetection faces could be reduced to two when the gap material was air.

  6. Optimizing light transport in scintillation crystals for time-of-flight PET: an experimental and optical Monte Carlo simulation study.

    Science.gov (United States)

    Berg, Eric; Roncali, Emilie; Cherry, Simon R

    2015-06-01

    Achieving excellent timing resolution in gamma ray detectors is crucial in several applications such as medical imaging with time-of-flight positron emission tomography (TOF-PET). Although many factors impact the overall system timing resolution, the statistical nature of scintillation light, including photon production and transport in the crystal to the photodetector, is typically the limiting factor for modern scintillation detectors. In this study, we investigated the impact of surface treatment, in particular, roughening select areas of otherwise polished crystals, on light transport and timing resolution. A custom Monte Carlo photon tracking tool was used to gain insight into changes in light collection and timing resolution that were observed experimentally: select roughening configurations increased the light collection up to 25% and improved timing resolution by 15% compared to crystals with all polished surfaces. Simulations showed that partial surface roughening caused a greater number of photons to be reflected towards the photodetector and increased the initial rate of photoelectron production. This study provides a simple method to improve timing resolution and light collection in scintillator-based gamma ray detectors, a topic of high importance in the field of TOF-PET. Additionally, we demonstrated utility of our Monte Carlo simulation tool to accurately predict the effect of altering crystal surfaces on light collection and timing resolution.

  7. Pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} on amorphous dielectric layers towards monolithic 3D photonic integration

    Energy Technology Data Exchange (ETDEWEB)

    Li, Haofeng; Brouillet, Jeremy; Wang, Xiaoxin; Liu, Jifeng, E-mail: Jifeng.Liu@dartmouth.edu [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States)

    2014-11-17

    We demonstrate pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} crystallized on amorphous layers at <450 °C towards 3D Si photonic integration. We developed two approaches to seed the lateral single crystal growth: (1) utilize the Gibbs-Thomson eutectic temperature depression at the tip of an amorphous GeSn nanotaper for selective nucleation; (2) laser-induced nucleation at one end of a GeSn strip. Either way, the crystallized Ge{sub 0.89}Sn{sub 0.11} is dominated by a single grain >18 μm long that forms optoelectronically benign twin boundaries with others grains. These pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} patterns are suitable for monolithic 3D integration of active photonic devices on Si.

  8. Study of PET scanner designs using clinical metrics to optimize the scanner axial FOV and crystal thickness

    Science.gov (United States)

    Surti, S.; Werner, M. E.; Karp, J. S.

    2013-06-01

    The aim of this study is to understand the trade-off between crystal thickness and scanner axial field-of-view FOV (AFOV) for clinical PET imaging. Clinical scanner design has evolved towards 20-25 mm thick crystals and 16-22 cm long scanner AFOV, as well as time-of-flight (TOF) imaging. While Monte Carlo studies demonstrate that longer AFOV and thicker crystals will lead to higher scanner sensitivity, cost has prohibited the building of commercial scanners with >22 cm AFOV. In this study, we performed a series of system simulations to optimize the use of a given amount of crystal material by evaluating the impact on system sensitivity and noise equivalent counts (NEC), as well as image quality in terms of lesion detectability. We evaluated two crystal types (LSO and LaBr3) and fixed the total crystal volume used for each type (8.2 L of LSO and 17.1 L of LaBr3) while varying the crystal thickness and scanner AFOV. In addition, all imaging times were normalized so that the total scan time needed to scan a 100 cm long object with multiple bed positions was kept constant. Our results show that the highest NEC cm-1 in a 35 cm diameter ×70 cm long line source cylinder is achieved for an LSO scanner with 10 mm long crystals and AFOV of 36 cm, while for LaBr3 scanners, the highest NEC cm-1 is obtained with 20 mm long crystals and an AFOV of 38 cm. Lesion phantom simulations show that the best lesion detection performance is achieved in scanners with long AFOV (≥36 cm) and using thin crystals (≤10 mm of LSO and ≤20 mm of LaBr3). This is due to a combination of improved NEC, as well as improved lesion contrast estimation due to better spatial resolution in thinner crystals. Alternatively, for lesion detection performance similar to that achieved in standard clinical scanner designs, the long AFOV scanners can be used to reduce the total scan time without increasing the amount of crystal used in the scanner. In addition, for LaBr3 based scanners, the reduced lesion

  9. Side readout of long scintillation crystal elements with digital SiPM for TOF-DOI PET.

    Science.gov (United States)

    Yeom, Jung Yeol; Vinke, Ruud; Levin, Craig S

    2014-12-01

    Side readout of scintillation light from crystal elements in positron emission tomography (PET) is an alternative to conventional end-readout configurations, with the benefit of being able to provide accurate depth-of-interaction (DOI) information and good energy resolution while achieving excellent timing resolution required for time-of-flight PET. This paper explores different readout geometries of scintillation crystal elements with the goal of achieving a detector that simultaneously achieves excellent timing resolution, energy resolution, spatial resolution, and photon sensitivity. The performance of discrete LYSO scintillation elements of different lengths read out from the end/side with digital silicon photomultipliers (dSiPMs) has been assessed. Compared to 3 × 3 × 20 mm(3) LYSO crystals read out from their ends with a coincidence resolving time (CRT) of 162 ± 6 ps FWHM and saturated energy spectra, a side-readout configuration achieved an excellent CRT of 144 ± 2 ps FWHM after correcting for timing skews within the dSiPM and an energy resolution of 11.8% ± 0.2% without requiring energy saturation correction. Using a maximum likelihood estimation method on individual dSiPM pixel response that corresponds to different 511 keV photon interaction positions, the DOI resolution of this 3 × 3 × 20 mm(3) crystal side-readout configuration was computed to be 0.8 mm FWHM with negligible artifacts at the crystal ends. On the other hand, with smaller 3 × 3 × 5 mm(3) LYSO crystals that can also be tiled/stacked to provide DOI information, a timing resolution of 134 ± 6 ps was attained but produced highly saturated energy spectra. The energy, timing, and DOI resolution information extracted from the side of long scintillation crystal elements coupled to dSiPM have been acquired for the first time. The authors conclude in this proof of concept study that such detector configuration has the potential to enable outstanding detector performance in terms of timing

  10. Side readout of long scintillation crystal elements with digital SiPM for TOF-DOI PET

    Energy Technology Data Exchange (ETDEWEB)

    Yeom, Jung Yeol, E-mail: yeomjy@kumoh.ac.kr, E-mail: cslevin@stanford.edu [Molecular Imaging Program at Stanford, Department of Radiology, Stanford University, Stanford, California 94305 and Department of Medical IT Convergence Engineering,Kumoh National Institute of Technology, Gumi, Gyeongbuk 730-701 (Korea, Republic of); Vinke, Ruud [Molecular Imaging Program at Stanford, Department of Radiology, Stanford University, Stanford, California 94305 (United States); Levin, Craig S., E-mail: yeomjy@kumoh.ac.kr, E-mail: cslevin@stanford.edu [Molecular Imaging Program at Stanford, Department of Radiology, Physics, and Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

    2014-12-15

    Purpose: Side readout of scintillation light from crystal elements in positron emission tomography (PET) is an alternative to conventional end-readout configurations, with the benefit of being able to provide accurate depth-of-interaction (DOI) information and good energy resolution while achieving excellent timing resolution required for time-of-flight PET. This paper explores different readout geometries of scintillation crystal elements with the goal of achieving a detector that simultaneously achieves excellent timing resolution, energy resolution, spatial resolution, and photon sensitivity. Methods: The performance of discrete LYSO scintillation elements of different lengths read out from the end/side with digital silicon photomultipliers (dSiPMs) has been assessed. Results: Compared to 3 × 3 × 20 mm{sup 3} LYSO crystals read out from their ends with a coincidence resolving time (CRT) of 162 ± 6 ps FWHM and saturated energy spectra, a side-readout configuration achieved an excellent CRT of 144 ± 2 ps FWHM after correcting for timing skews within the dSiPM and an energy resolution of 11.8% ± 0.2% without requiring energy saturation correction. Using a maximum likelihood estimation method on individual dSiPM pixel response that corresponds to different 511 keV photon interaction positions, the DOI resolution of this 3 × 3 × 20 mm{sup 3} crystal side-readout configuration was computed to be 0.8 mm FWHM with negligible artifacts at the crystal ends. On the other hand, with smaller 3 × 3 × 5 mm{sup 3} LYSO crystals that can also be tiled/stacked to provide DOI information, a timing resolution of 134 ± 6 ps was attained but produced highly saturated energy spectra. Conclusions: The energy, timing, and DOI resolution information extracted from the side of long scintillation crystal elements coupled to dSiPM have been acquired for the first time. The authors conclude in this proof of concept study that such detector configuration has the potential to enable

  11. 增容对回收PET/PP共混物的结晶与熔融行为的影响%Effect of Compatibilization on Crystallization and Melting Behavior of Recycled Poly (ethylene terephthalate) and Polypropylene Blends

    Institute of Scientific and Technical Information of China (English)

    王春广; 林劲新; 章自寿; 麦堪成

    2012-01-01

    The recycled poly (ethylene terephthalate) /polypropylene (r-PET/PP) blends were prepared with different compatibilizers. The differential scanning calorimetry (DSC) was used to investigate the effect of compatibilizers on crystallization and melting behavior of r-PET, the effect of r-PET on crystallization and melting behavior of PP and the effect of compatibilizers on crystallization and melting behavior of r-PET/PP blends. The results indicated that the crystallization temperatures of PP increased with increasing r-PET contents and the crystallization temperatures of r-PET decreased with increasing PP contents. Addition of compatibilizers significantly decreased the crystallization temperatures of neat r-PET and r-PET component in the blends. However , the different compatibilizers had no influence on the crystallization and melting behavior of blends and the crystallization behavior of PP in the blends depend on the kinds of compatibilizers.%制备了不同相容剂增容回收PET/PP共混物,用DSC方法研究了相容剂对r-PET结晶与熔融行为的影响,r-PET对PP结晶与熔融行为的影响和相容剂对r-PET/PP共混物结晶与熔融行为的影响,观察到PP结晶温度随着r-PET含量增加而提高,r-PET结晶温度随着PP含量增加而降低,相容剂加入明显降低共混物中r-PET结晶温度,但不同相容剂对共混物中r-PET结晶与熔融行为影响不大,共混物中PP结晶性能与相容剂的大分子链有关.

  12. Performance of a monolithic LaBr{sub 3}:Ce crystal coupled to an array of silicon photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Ulyanov, Alexei, E-mail: alexey.uliyanov@ucd.ie [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Morris, Oran [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Department of Computer Science & Applied Physics, Galway-Mayo Institute of Technology, Galway (Ireland); Hanlon, Lorraine; McBreen, Sheila; Foley, Suzanne; Roberts, Oliver J.; Tobin, Isaac; Murphy, David; Wade, Colin [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Nelms, Nick; Shortt, Brian [European Space Agency, ESTEC, 2200 AG Noordwijk (Netherlands); Slavicek, Tomas; Granja, Carlos; Solar, Michael [Institute of Experimental and Applied Physics, Czech Technical University in Prague, 12800 Prague 2 (Czech Republic)

    2016-02-21

    A gamma-ray detector composed of a single 28×28×20 mm{sup 3} LaBr{sub 3}:Ce crystal coupled to a custom built 4×4 array of silicon photomultipliers was tested over an energy range of 30 keV to 9.3 MeV. The silicon photomultipliers were initially calibrated using 20 ns light pulses generated by a light emitting diode. The photodetector responses measured as a function of the number of incident photons were found to be non-linear and consistent with model predictions. Using corrections for the non-linearity of the silicon photomultipliers, the detector showed a linear response to gamma-rays with energies from 100 keV to the maximum available energy of 9.3 MeV. The energy resolution was found to be 4% FWHM at 662 keV. Despite the large thickness of the scintillator (20 mm) and a 5 mm thick optical window, the detector was capable of measuring the positions of the gamma-ray interaction points. The position resolution was measured at 356 keV and was found to be 8 mm FWHM in the detector plane and 11 mm FWHM for the depth of interaction. The detector can be used as a building block of a larger calorimeter system that is capable of measuring gamma-ray energies up to tens of MeV.

  13. 钛系聚酯预结晶性能探索%The exploration of pre-crystallization properties of PET synthesized with Ti-based catalyst

    Institute of Scientific and Technical Information of China (English)

    王玉合; 戴钧明; 王树霞; 司虎

    2013-01-01

    The pre-crystallization properties of PET synthesized with Ti-based catalyst was investigated using differential scanning calorimetry (DSC).And the studied results was compared with the Sb-based catalyst synthe-sized PET polyesters.Results indicate that the PET polyester chips which synthesized with Ti-based catalyst have low degree of residual crystallinity and slower cold crystallization speed.And the Ti-based chips also easier to bond-ing under the same process condition compared with the Sb-based chips.%主要通过 DSC 对钛催化剂合成 PET 聚酯的预结晶性能进行了研究,以探索钛催化剂对聚酯预结晶性能的影响,并将其与锑系聚酯进行对比。结果表明,相比较锑系聚酯,钛催化剂合成 PET 聚酯切片内部残留结晶度低,冷结晶速度慢,同样工艺条件下钛系聚酯预结晶过程更容易粘结。

  14. X-ray crystal structure of the passenger domain of plasmid encoded toxin(Pet), an autotransporter enterotoxin from enteroaggregative Escherichia coli (EAEC)

    Energy Technology Data Exchange (ETDEWEB)

    Domingo Meza-Aguilar, J. [Departamento de Salud Pública Facultad de Medicina UNAM, Ciudad Universitaria Coyoacán 04510, D.F. (Mexico); Laboratorio de Patogenicidad Bacteriana, Unidad de Hemato Oncología e Investigación, Hospital Infantil de México Federico Gómez 06720, D.F. (Mexico); Fromme, Petra [Department of Chemistry and Biochemistry, Arizona State University, Physical Sciences BLDG D-102, Tempe, AZ 85287 (United States); Torres-Larios, Alfredo [Instituto de Fisiología Celular UNAM, Ciudad Universitaria Coyoacán 04510, D.F. (Mexico); Mendoza-Hernández, Guillermo [Instituto de Química UNAM, Ciudad Universitaria Coyoacán 04510, D.F (Mexico); Hernandez-Chiñas, Ulises [Departamento de Salud Pública Facultad de Medicina UNAM, Ciudad Universitaria Coyoacán 04510, D.F. (Mexico); Laboratorio de Patogenicidad Bacteriana, Unidad de Hemato Oncología e Investigación, Hospital Infantil de México Federico Gómez 06720, D.F. (Mexico); Arreguin-Espinosa de los Monteros, Roberto A. [Instituto de Química UNAM, Ciudad Universitaria Coyoacán 04510, D.F (Mexico); and others

    2014-03-07

    Highlights: • X-ray crystal structure of the passenger domain of Plasmid encoded toxin at 2.3 Å. • Structural differences between Pet passenger domain and EspP protein are described. • High flexibility of the C-terminal beta helix is structurally assigned. - Abstract: Autotransporters (ATs) represent a superfamily of proteins produced by a variety of pathogenic bacteria, which include the pathogenic groups of Escherichia coli (E. coli) associated with gastrointestinal and urinary tract infections. We present the first X-ray structure of the passenger domain from the Plasmid-encoded toxin (Pet) a 100 kDa protein at 2.3 Å resolution which is a cause of acute diarrhea in both developing and industrialized countries. Pet is a cytoskeleton-altering toxin that induces loss of actin stress fibers. While Pet (pdb code: 4OM9) shows only a sequence identity of 50% compared to the closest related protein sequence, extracellular serine protease plasmid (EspP) the structural features of both proteins are conserved. A closer structural look reveals that Pet contains a β-pleaded sheet at the sequence region of residues 181–190, the corresponding structural domain in EspP consists of a coiled loop. Secondary, the Pet passenger domain features a more pronounced beta sheet between residues 135 and 143 compared to the structure of EspP.

  15. Monolithic all-PM femtosecond Yb-fiber laser stabilized with a narrow-band fiber Bragg grating and pulse-compressed in a hollow-core photonic crystal fiber

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

    2008-01-01

    We report on an environmentally stable self-starting monolithic (i.e. without any free-space coupling) all-polarization-maintaining (PM) femtosecond Yb-fiber laser, stabilized against Q-switching by a narrow-band fiber Bragg grating and modelocked using a semiconductor saturable absorber mirror....... The laser output is compressed in a spliced-on hollow-core PM photonic crystal fiber, thus providing direct end-of-the-fiber delivery of pulses of around 370 fs duration and 4 nJ energy with high mode quality. Tuning the pump power of the end amplifier of the laser allows for the control of output pulse...

  16. Monoliths in Bioprocess Technology

    Directory of Open Access Journals (Sweden)

    Vignesh Rajamanickam

    2015-04-01

    Full Text Available Monolithic columns are a special type of chromatography column, which can be used for the purification of different biomolecules. They have become popular due to their high mass transfer properties and short purification times. Several articles have already discussed monolith manufacturing, as well as monolith characteristics. In contrast, this review focuses on the applied aspect of monoliths and discusses the most relevant biomolecules that can be successfully purified by them. We describe success stories for viruses, nucleic acids and proteins and compare them to conventional purification methods. Furthermore, the advantages of monolithic columns over particle-based resins, as well as the limitations of monoliths are discussed. With a compilation of commercially available monolithic columns, this review aims at serving as a ‘yellow pages’ for bioprocess engineers who face the challenge of purifying a certain biomolecule using monoliths.

  17. Design and evaluation of the MAMMI dedicated breast PET

    Energy Technology Data Exchange (ETDEWEB)

    Moliner, L.; Gonzalez, A. J.; Soriano, A.; Sanchez, F.; Correcher, C.; Orero, A.; Carles, M.; Vidal, L. F.; Barbera, J.; Caballero, L.; Seimetz, M.; Vazquez, C.; Benlloch, J. M. [Instituto de Instrumentacion para Imagen Molecular (I3M), Centro Mixto CSIC, Universitat Politecnica de Valencia, CIEMAT, Camino de Vera s/n, 46022 Valencia (Spain); Instituto de Instrumentacion para Imagen Molecular (I3M), Centro Mixto CSIC, Universitat Politecnica de Valencia, CIEMAT, Camino de Vera s/n, 46022 Valencia (Spain) and Oncovision, GEM-Imaging SA. 46012 Valencia (Spain); Instituto de Instrumentacion para Imagen Molecular (I3M), Centro Mixto CSIC, Universitat Politecnica de Valencia, CIEMAT, Camino de Vera s/n, 46022 Valencia (Spain); Oncovision, GEM-Imaging SA. 46012 Valencia (Spain); Instituto de Instrumentacion para Imagen Molecular (I3M), Centro Mixto CSIC, Universitat Politecnica de Valencia, CIEMAT, Camino de Vera s/n, 46022 Valencia (Spain); Oncovision, GEM-Imaging SA. 46012 Valencia (Spain); Instituto de Instrumentacion para Imagen Molecular (I3M), Centro Mixto CSIC, Universitat Politecnica de Valencia, CIEMAT, Camino de Vera s/n, 46022 Valencia (Spain)

    2012-09-15

    Purpose: A breast dedicated positron emission tomography (PET) scanner has been developed based on monolithic LYSO crystals coupled to position sensitive photomultiplier tubes (PSPMTs). In this study, we describe the design of the PET system and report on its performance evaluation. Methods: MAMMI is a breast PET scanner based on monolithic LYSO crystals. It consists of 12 compact modules with a transaxial field of view (FOV) of 170 mm in diameter and 40 mm axial FOV that translates to cover up to 170 mm. The patient lies down in a prone position that facilitates maximum breast elongation. Quantitative performance analysis of the calculated method for the attenuation correction specifically developed for MAMMI, and based on PET image segmentation, has also been conducted in this evaluation. In order to fully determine the MAMMI prototype's performance, we have adapted the measurements suggested for National Electrical Manufacturers Association (NEMA) NU 2-2007 and NU 4-2008 protocol tests, as they are defined for whole-body and small animal PET scanners, respectively. Results: Spatial resolutions of 1.6, 1.8, and 1.9 mm were measured in the axial, radial, and tangential directions, respectively. A scatter fraction of 20.8% was obtained and the maximum NEC was determined to be 25 kcps at 44 MBq. The average sensitivity of the system was observed to be 1% for an energy window of (250 keV-750 keV) and a maximum absolute sensitivity of 1.8% was measured at the FOV center. Conclusions: The overall performance of the MAMMI reported on this evaluation quantifies its ability to produce high quality PET images. Spatial resolution values below 3 mm were measured in most of the FOV. Only the radial component of spatial resolution exceeds the 3 mm at radial positions larger than 60 mm. This study emphasizes the need for standardized testing methodologies for dedicated breast PET systems similar to NEMA standards for whole-body and small animal PET scanners.

  18. Time-based position estimation in monolithic scintillator detectors

    NARCIS (Netherlands)

    Tabacchini, V.; Borghi, G.; Schaart, D.R.

    2015-01-01

    Gamma-ray detectors based on bright monolithic scintillation crystals coupled to pixelated photodetectors are currently being considered for several applications in the medical imaging field. In a typical monolithic detector, both the light intensity and the time of arrival of the earliest

  19. Time-based position estimation in monolithic scintillator detectors

    NARCIS (Netherlands)

    Tabacchini, V.; Borghi, G.; Schaart, D.R.

    2015-01-01

    Gamma-ray detectors based on bright monolithic scintillation crystals coupled to pixelated photodetectors are currently being considered for several applications in the medical imaging field. In a typical monolithic detector, both the light intensity and the time of arrival of the earliest scintilla

  20. Time-based position estimation in monolithic scintillator detectors

    NARCIS (Netherlands)

    Tabacchini, V.; Borghi, G.; Schaart, D.R.

    2015-01-01

    Gamma-ray detectors based on bright monolithic scintillation crystals coupled to pixelated photodetectors are currently being considered for several applications in the medical imaging field. In a typical monolithic detector, both the light intensity and the time of arrival of the earliest scintilla

  1. Development and evaluation of a LOR-based image reconstruction with 3D system response modeling for a PET insert with dual-layer offset crystal design

    Science.gov (United States)

    Zhang, Xuezhu; Stortz, Greg; Sossi, Vesna; Thompson, Christopher J.; Retière, Fabrice; Kozlowski, Piotr; Thiessen, Jonathan D.; Goertzen, Andrew L.

    2013-12-01

    In this study we present a method of 3D system response calculation for analytical computer simulation and statistical image reconstruction for a magnetic resonance imaging (MRI) compatible positron emission tomography (PET) insert system that uses a dual-layer offset (DLO) crystal design. The general analytical system response functions (SRFs) for detector geometric and inter-crystal penetration of coincident crystal pairs are derived first. We implemented a 3D ray-tracing algorithm with 4π sampling for calculating the SRFs of coincident pairs of individual DLO crystals. The determination of which detector blocks are intersected by a gamma ray is made by calculating the intersection of the ray with virtual cylinders with radii just inside the inner surface and just outside the outer-edge of each crystal layer of the detector ring. For efficient ray-tracing computation, the detector block and ray to be traced are then rotated so that the crystals are aligned along the X-axis, facilitating calculation of ray/crystal boundary intersection points. This algorithm can be applied to any system geometry using either single-layer (SL) or multi-layer array design with or without offset crystals. For effective data organization, a direct lines of response (LOR)-based indexed histogram-mode method is also presented in this work. SRF calculation is performed on-the-fly in both forward and back projection procedures during each iteration of image reconstruction, with acceleration through use of eight-fold geometric symmetry and multi-threaded parallel computation. To validate the proposed methods, we performed a series of analytical and Monte Carlo computer simulations for different system geometry and detector designs. The full-width-at-half-maximum of the numerical SRFs in both radial and tangential directions are calculated and compared for various system designs. By inspecting the sinograms obtained for different detector geometries, it can be seen that the DLO crystal

  2. A Small-Animal PET System Based on LYSO Crystal Arrays, PS-PMTs and a PCI DAQ Board

    Science.gov (United States)

    Alva-Sanchez, H.; Murrieta, T.; Moreno-Barbosa, E.; Brandan, M. E.; Ruiz-Trejo, C.; Martinez-Davalos, A.; Rodriguez-Villafuerte, M.

    2010-02-01

    A positron emission tomography system for small animals has been designed for research purposes, and developed at Instituto de Fi¿sica, UNAM, Mexico. Its detection modules are based on pixelated scintillator LYSO crystal arrays coupled to Hamamatsu H8500 position-sensitive photomultiplier tubes. The front-end electronics are based on nuclear instrumentation modules (NIM) and in-house built readout circuits. Peak signal digitization is performed with a commercial analogue-to-digital acquisition (DAQ) board. The system has been characterized for spatial, timing and energy resolution, system dead time, absolute sensitivity, scatter fraction and noise equivalent count rate (NEC). The results indicate that the detection modules are able to identify individual crystals (out of 400) with up to 8-to-1 peak-to-valley ratios with individual crystal energy resolution ranging from 7 to 15% at 511 keV. The timing resolution is 1.9 ns and the system dead time was found to be 16.8 ¿s and 42.1 ¿s for 0.5 ml and 10 ml volume sources, respectively. The measured absolute system sensitivity is 0.11% and the scatter fraction from a glass capillary inside a 2.5 cm diameter mouse phantom is 21.5%. A true NEC maximum value was not achieved with the system due to saturation of the PS-PMT output signals for activities above 0.27 mCi. Results from a Na18 F PET bone scan of a 30 g mouse are shown.

  3. Implementation and analysis of list mode algorithm using tubes of response on a dedicated brain and breast PET

    Energy Technology Data Exchange (ETDEWEB)

    Moliner, L. [Instituto de Instrumentación para Imagen Molecular (I3M). Centro Mixto UPV-CSIC-CIEMAT. Camino de Vera s/n, 46022 Valencia (Spain); Correcher, C. [ONCOVISION (GEM-Imaging S.A.), 46012 Valencia (Spain); González, A.J., E-mail: agonzalez@i3m.upv.es [Instituto de Instrumentación para Imagen Molecular (I3M). Centro Mixto UPV-CSIC-CIEMAT. Camino de Vera s/n, 46022 Valencia (Spain); Conde, P.; Hernández, L.; Orero, A.; Rodríguez-Álvarez, M.J.; Sánchez, F.; Soriano, A.; Vidal, L.F.; Benlloch, J.M. [Instituto de Instrumentación para Imagen Molecular (I3M). Centro Mixto UPV-CSIC-CIEMAT. Camino de Vera s/n, 46022 Valencia (Spain)

    2013-02-21

    In this work we present an innovative algorithm for the reconstruction of PET images based on the List-Mode (LM) technique which improves their spatial resolution compared to results obtained with current MLEM algorithms. This study appears as a part of a large project with the aim of improving diagnosis in early Alzheimer disease stages by means of a newly developed hybrid PET-MR insert. At the present, Alzheimer is the most relevant neurodegenerative disease and the best way to apply an effective treatment is its early diagnosis. The PET device will consist of several monolithic LYSO crystals coupled to SiPM detectors. Monolithic crystals can reduce scanner costs with the advantage to enable implementation of very small virtual pixels in their geometry. This is especially useful for LM reconstruction algorithms, since they do not need a pre-calculated system matrix. We have developed an LM algorithm which has been initially tested with a large aperture (186 mm) breast PET system. Such an algorithm instead of using the common lines of response, incorporates a novel calculation of tubes of response. The new approach improves the volumetric spatial resolution about a factor 2 at the border of the field of view when compared with traditionally used MLEM algorithm. Moreover, it has also shown to decrease the image noise, thus increasing the image quality.

  4. Study of a high-resolution, 3-D positioning cadmium zinc telluride detector for PET

    OpenAIRE

    Gu, Y.; Matteson, J. L.; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

    2011-01-01

    This paper investigates the performance of 1 mm resolution Cadmium Zinc Telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3-D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06±0.39% at 511 keV thr...

  5. A SiPM-based isotropic-3D PET detector X'tal cube with a three-dimensional array of 1 mm(3) crystals.

    Science.gov (United States)

    Yamaya, Taiga; Mitsuhashi, Takayuki; Matsumoto, Takahiro; Inadama, Naoko; Nishikido, Fumihiko; Yoshida, Eiji; Murayama, Hideo; Kawai, Hideyuki; Suga, Mikio; Watanabe, Mitsuo

    2011-11-07

    We are developing a novel, general purpose isotropic-3D PET detector X'tal cube which has high spatial resolution in all three dimensions. The research challenge for this detector is implementing effective detection of scintillation photons by covering six faces of a segmented crystal block with silicon photomultipliers (SiPMs). In this paper, we developed the second prototype of the X'tal cube for a proof-of-concept. We aimed at realizing an ultimate detector with 1.0 mm(3) cubic crystals, in contrast to our previous development using 3.0 mm(3) cubic crystals. The crystal block was composed of a 16 × 16 × 16 array of lutetium gadolinium oxyorthosilicate (LGSO) crystals 0.993 × 0.993 × 0.993 mm(3) in size. The crystals were optically glued together without inserting any reflector inside and 96 multi-pixel photon counters (MPPCs, S10931-50P, i.e. six faces each with a 4 × 4 array of MPPCs), each having a sensitive area of 3.0 × 3.0 mm(2), were optically coupled to the surfaces of the crystal block. Almost all 4096 crystals were identified through Anger-type calculation due to the finely adjusted reflector sheets inserted between the crystal block and light guides. The reflector sheets, which formed a belt of 0.5 mm width, were placed to cover half of the crystals of the second rows from the edges in order to improve identification performance of the crystals near the edges. Energy resolution of 12.7% was obtained at 511 keV with almost uniform light output for all crystal segments thanks to the effective detection of the scintillation photons.

  6. Prototype pre-clinical PET scanner with depth-of-interaction measurements using single-layer crystal array and single-ended readout

    Science.gov (United States)

    Lee, Min Sun; Kim, Kyeong Yun; Ko, Guen Bae; Lee, Jae Sung

    2017-05-01

    In this study, we developed a proof-of-concept prototype PET system using a pair of depth-of-interaction (DOI) PET detectors based on the proposed DOI-encoding method and digital silicon photomultiplier (dSiPM). Our novel cost-effective DOI measurement method is based on a triangular-shaped reflector that requires only a single-layer pixelated crystal and single-ended signal readout. The DOI detector consisted of an 18  ×  18 array of unpolished LYSO crystal (1.47  ×  1.47  ×  15 mm3) wrapped with triangular-shaped reflectors. The DOI information was encoded by depth-dependent light distribution tailored by the reflector geometry and DOI correction was performed using four-step depth calibration data and maximum-likelihood (ML) estimation. The detector pair and the object were placed on two motorized rotation stages to demonstrate 12-block ring PET geometry with 11.15 cm diameter. Spatial resolution was measured and phantom and animal imaging studies were performed to investigate imaging performance. All images were reconstructed with and without the DOI correction to examine the impact of our DOI measurement. The pair of dSiPM-based DOI PET detectors showed good physical performances respectively: 2.82 and 3.09 peak-to-valley ratios, 14.30% and 18.95% energy resolution, and 4.28 and 4.24 mm DOI resolution averaged over all crystals and all depths. A sub-millimeter spatial resolution was achieved at the center of the field of view (FOV). After applying ML-based DOI correction, maximum 36.92% improvement was achieved in the radial spatial resolution and a uniform resolution was observed within 5 cm of transverse PET FOV. We successfully acquired phantom and animal images with improved spatial resolution and contrast by using the DOI measurement. The proposed DOI-encoding method was successfully demonstrated in the system level and exhibited good performance, showing its feasibility for animal PET applications with high spatial

  7. Depth of interaction determination in monolithic scintillator with double side SiPM readout.

    Science.gov (United States)

    Morrocchi, Matteo; Ambrosi, Giovanni; Bisogni, Maria Giuseppina; Bosi, Filippo; Boretto, Marco; Cerello, Piergiorgio; Ionica, Maria; Liu, Ben; Pennazio, Francesco; Piliero, Maria Antonietta; Pirrone, Giovanni; Postolache, Vasile; Wheadon, Richard; Del Guerra, Alberto

    2017-12-01

    Monolithic scintillators read out by arrays of photodetectors represent a promising solution to obtain high spatial resolution and the depth of interaction (DOI) of the annihilation photon. We have recently investigated a detector geometry composed of a monolithic scintillator readout on two sides by silicon photomultiplier (SiPM) arrays, and we have proposed two parameters for the DOI determination: the difference in the number of triggered SiPMs on the two sides of the detector and the difference in the maximum collected signal on a single SiPM on each side. This work is focused on the DOI calibration and on the determination of the capability of our detector. For the DOI calibration, we studied a method which can be implemented also in detectors mounted in a full PET scanner. We used a PET detector module composed of a monolithic 20 × 20 × 10 mm(3) LYSO scintillator crystal coupled on two opposite faces to two arrays of SiPMs. On each side, the scintillator was coupled to 6 × 6 SiPMs. In this paper, the two parameters previously proposed for the DOI determination were calibrated with two different methods. The first used a lateral scan of the detector with a collimated 511 keV pencil beam at steps of 0.5 mm to study the detector DOI capability, while the second used the background radiation of the (176)Lu in the scintillator. The DOI determination capability was tested on different regions of the detector using each parameter and the combination of the two. With both parameters for the DOI determination, in the lateral scan, the bias between the mean reconstructed DOI and the real beam position was lower than 0.3 mm, and the DOI distribution had a standard deviation of about 1.5 mm. When using the calibration with the radioactivity of the LYSO, the mean bias increased of about 0.2 mm but with no degradation of the standard deviation of the DOI distribution. The two parameters allow to achieve a DOI resolution comparable with the state of the

  8. The Readout Electronics for the Continuous Crystal PET Detector Module%基于连续晶体 PET 探测器模块电子学设计

    Institute of Scientific and Technical Information of China (English)

    周宇; 王永纲

    2014-01-01

    和传统的基于分割晶体PET探测器相比,基于连续晶体的PET探测器具有设计结构简单、能量分辨率高、探测器效率高以及低造价等优点,近年来得到广泛的研究。基于连续晶体PET探测器的最大难点是要用探测器获得闪烁光分布,进而通过作用点定位算法计算γ光子的作用位置。探测器模块电子学需要读出和获取闪烁光的分布,因而电子学变得相对复杂。论文针对自行建立的基于连续LYSO晶体和神经网络定位算法的PET探测器模块的信号读出和数据获取的要求,设计和实现了64通道数据读出和获取电子学系统。该系统采用8片8通道、50 Mbps、串行输出、12 bit ADC对每个通道进行数字化,从海量的核事例中遴选出有效的核事例,在FPGA内实现数据打包、定时符合、基线恢复等功能。经过测试,电路各通道噪声低,增益一致性好。整个电子学系统结构紧凑、性能优良,适合基于连续晶体PET探测器的相关实验研究和应用研究。%Compared with PET detectors basing on the traditional split crystals ,PET detectors basing on continu-ous crystals having a simple structure , high energy resolution and the detector efficiency is high , as well as low cost, etc..The biggest difficulty of the continuous crystal PET detector is using the probe to get the blinking light distribution to calculate the interaction point of the γ-photon by the interaction point position algorithm . The detector module electronics needs to read out and obtain the distribution of the scintillation light , and thus reading out and data acquisition electronics becomes relatively complex .In this paper , we create our own PET detector basing on continuous LYSO crystals and neural network positioning algorithm module , design and real-ize 64 channel data acquisition and readout electronics system .The system uses eight 8-channel, 50Mbps, 12bit ADC for each channel to

  9. Effect of compatibilizer on non-isothermal crystallization kinetics of PP/r-PET blends%增容剂对PP/r-PET共混物非等温结晶动力学的影响

    Institute of Scientific and Technical Information of China (English)

    周红军; 卢永乐; 何桂銮

    2013-01-01

    The effect of the compatibilizer of glycidyl methacrylate-grafted polypropylene (PP-g-GMA) on the non-isothermal crystallization kinetics of polypropylene (PP)/recycled polyethylene terephthalate (r-PET) blend were investigated by differential scanning calorimetry. The results showed that r-PET had a heterogeneous nucleation effect in PP/r-PET blend system, resulting in an elevation of PP crystallization peak temperature and a decrease in the half-crystallization time of the blend system ; the addition of PP-g-GMA decreased the crystallization temperature of PP/r-PET and increased the half-crstallization time, but depressed the crystallization activation energy of PP.%采用差示扫描量热法研究了增容剂甲基丙烯酸缩水甘油酯接枝聚丙烯(PP-g-GMA)对聚丙烯(PP)/回收聚对苯二甲酸乙二酯(r-PET)共混物的非等温结晶动力学的影响.结果表明:在PP/r-PET共混体系中,r-PET起到异相成核的作用,PP的结晶峰温升高,半结晶时间减少;增容剂PP-g-GMA的加入使PP/r-PET的结晶温度降低,半结晶时间增大,但降低了PP的结晶活化能.

  10. High-repetition-rate quasi-CW side-pumped mJ eye-safe laser with a monolithic KTP crystal for intracavity optical parametric oscillator.

    Science.gov (United States)

    Cho, C Y; Chen, Y C; Huang, Y P; Huang, Y J; Su, K W; Chen, Y F

    2014-04-01

    We demonstrate a high-repetition-rate millijoule passively Q-switched eye-safe Nd:YVO(4) laser pumped by a quasi-CW diode stack. A theoretical analysis has been explored for the design criteria of generating TEM(n,0) mode in the diode-stack directly side-pumping configuration. We successfully generate TEM(n,0) modes at 1064 nm by adjusting the gain medium with respected to the laser axis. We further observe the spatial cleaning ability for generating an nearly TEM(0,0) mode output at 1573 nm with a monolithic OPO cavity. At the repetition rate up to 200 Hz, the output pulse energy reaches 1.21 mJ with the threshold pump energy of 17.9 mJ.

  11. Low-loss polarization-maintaining fusion splicing of single-mode fibers and hollow-core photonic crystal fibers, relevant for monolithic fiber laser pulse compression

    DEFF Research Database (Denmark)

    Kristensen, Jesper Toft; Houmann, Andreas; Liu, Xiaomin;

    2008-01-01

    B. The reciprocal HC-PCF-to-PM-SMF splice loss is found to be 2.19 ± 0.33 dB, which is caused by the mode evolution in HC-PCF. The return loss in both cases was measured to be −14 dB. We show that a splice defect is caused by the HC-PCF cleave defect, and the lossy splice can be predicted at an early stage...... of the splicing process. We also demonstrate that the higher splice loss compromises the PM properties of the splice. Our splicing technique was successfully applied to the realization of a low-loss, environmentally stable monolithic PM fiber laser pulse compressor, enabling direct end-of-the-fiber femtosecond...

  12. Preparation and characterization of polystyrene-based monolith with ordered macroporous structure

    Institute of Scientific and Technical Information of China (English)

    Quan Zhou Wu; Jian Feng He; Ji Ming Ou

    2012-01-01

    In this paper,polystyrene-based monoliths with highly ordered macroporous structure were synthesized by using SiO2 colloidal crystal as template.SEM observation shows that the macropores are highly ordered and are interconnected by small windows.The BET surface area of PS monolith is about 36.17 m2/g.The polymer monoliths can resist 5 MPa pressure,showing high mechanical and compressive strength.

  13. Monolithic microwave integrated circuits

    Science.gov (United States)

    Pucel, R. A.

    Monolithic microwave integrated circuits (MMICs), a new microwave technology which is expected to exert a profound influence on microwave circuit designs for future military systems as well as for the commercial and consumer markets, is discussed. The book contains an historical discussion followed by a comprehensive review presenting the current status in the field. The general topics of the volume are: design considerations, materials and processing considerations, monolithic circuit applications, and CAD, measurement, and packaging techniques. All phases of MMIC technology are covered, from design to testing.

  14. Advantages and pitfalls of the silicon photomultiplier (SiPM) as photodetector for the next generation of PET scanners

    Energy Technology Data Exchange (ETDEWEB)

    Del Guerra, Alberto, E-mail: alberto.delguerra@df.unipi.i [Department of Physics, University of Pisa, Pisa I-56127 (Italy); INFN, Sezione di Pisa, Pisa I-56127 (Italy); Belcari, Nicola; Giuseppina Bisogni, Maria [Department of Physics, University of Pisa, Pisa I-56127 (Italy); INFN, Sezione di Pisa, Pisa I-56127 (Italy); LLosa, Gabriela [Department of Physics, University of Pisa, Pisa I-56127 (Italy); Marcatili, Sara [Department of Physics, University of Pisa, Pisa I-56127 (Italy); INFN, Sezione di Pisa, Pisa I-56127 (Italy); Ambrosi, Giovanni [INFN Sezione di Perugia, Perugia 10-06100 (Italy); Corsi, Franco; Marzocca, Cristoforo [DEE, Politecnico di Bari, I-70125 Bari (Italy); INFN Sezione di Bari, I-70125 Bari (Italy); Dalla Betta, Gianfranco [Department of Information and Communication Technology, University of Trento, I-38050 Povo di Trento (Italy); INFN Sezione di Trento, 38100 Povo di Trento (Italy); Piemonte, Claudio [FBK-irst, Center for Materials and Microsystems, I-38050 Povo di Trento (Italy)

    2010-05-21

    Silicon photomultipliers (SiPM) are a novel type of photodetectors that show great promise for nuclear medicine applications and especially for the next generation of PET scanners. The INFN collaboration DASIPM2 is investigating in depth the properties of the SiPM developed at FBK-irst (Trento, Italy), whose performance compete successfully with those of similar devices produced by commercial companies, but have in addition novel and attractive properties, such as monolithic matrix arrangement. In this paper we illustrate the advantages and pitfalls of the SiPM for PET applications. In particular we report on the most recent experimental results for SiPM and SiPM matrices performances: (i) an intrinsic very good time resolution that coupled to a high PDE could favor time-of-flight PET exploitation; (ii) very high photodetector granularity that allows position determination with continuous crystal and possibly stacking of several layers, i.e., Depth Of Interaction information capability thus paving the way for the construction for the next generation of PET cameras; (iii) MRI compatibility in magnetic field and magnetic field gradient, thus giving the possibility of constructing a state-of-the-art PET insert within an MRI scanner.

  15. Geo-PET: A novel generic organ-pet for small animal organs and tissues

    Science.gov (United States)

    Sensoy, Levent

    reconstruct tomographic images. Results demonstrate good agreement between the simulation and the prototype. Our detector system with pixelated crystals is able to separate small objects as close as 1.25 mm apart, whereas spatial resolution converges to the theoretical limit of 1.6 mm (half the size of the smallest detecting element), which is to comparable to the spatial resolution of the existing commercial small animal PET systems. Better system spatial resolution is achievable with new generation SiPM detector boards with 1 mm x 1 mm cell dimensions. We demonstrate through Monte Carlo simulations that it is possible to achieve sub-millimeter spatial image resolution (0.7 mm for our scanner) in complex objects using monolithic crystals and exploiting the light-sharing mechanism among the neighboring detector cells. Results also suggest that scanner (or object) rotation minimizes artifacts arising from poor angular sampling, which is even more significant in smaller PET designs as the gaps between the sensitive regions of the detector have a more exaggerated effect on the overall reconstructed image quality when the design is more compact. Sensitivity of the system, on the other hand, can be doubled by adding two additional detector heads resulting in a, fully closed, 4? geometry.

  16. Embedded-monolith armor

    Science.gov (United States)

    McElfresh, Michael W.; Groves, Scott E; Moffet, Mitchell L.; Martin, Louis P.

    2016-07-19

    A lightweight armor system utilizing a face section having a multiplicity of monoliths embedded in a matrix supported on low density foam. The face section is supported with a strong stiff backing plate. The backing plate is mounted on a spall plate.

  17. Comparison of two commercial whole body PET systems based on LSO and BGO crystals respectively for brain imaging.

    Science.gov (United States)

    Trébossen, Régine; Comtat, Claude; Brulon, Vincent; Bailly, Pascal; Meyer, Marc-Etienne

    2009-04-01

    The prevalence of neurodegenerative diseases is growing in western countries and PET imaging is increasingly frequently used for clinical and research purposes. However, few PET cameras are dedicated to cerebral imaging. The Biograph 6 (Biograph6) (Siemens Medical Solutions) is a PET/CT dedicated to high throughput whole body studies. Its performance for cerebral imaging has not yet been assessed. The aims of this study were to compare the quantification and detectability of the Biograph for cerebral imaging with those of a well-validated PET camera, the ECAT EXACT HR+ (HR+) (Siemens Medical Solutions). A phantom measuring 19 cm long and 20 cm in diameter was filled with a 18F-fluorodeoxyglucose (18F-FDG) solution. Two 5.7 and 20 ml spheres filled with water (cold-spots), three 0.25 ml spheres (sphere-to-background: 3, 6, and 12), one 1.14 ml sphere (sphere-to-background: 3), and one 11.27 ml sphere (sphere-to-background: 2) filled with a radioactive solution were inserted into the phantom. The activity concentration was chosen so that the count rates for the phantom measurements matched those of typical brain studies on both cameras. Images were reconstructed using FORE and OSEM algorithms. The reconstruction parameters were adjusted to obtain a similar signal-to-noise ratio in images acquired with the two cameras. The contrast recovery (CR) coefficients were similar on the two scanners for the 5.7 and 20 ml spheres (cold spheres) and the 1.14 and 11.27 ml spheres (hot spheres). For the 0.25 ml spheres, the CR values were 35% higher for the sphere-to-background ratio of 12 and 39% higher for the sphere-to-background ratio of 6 on the Biograph6 for the 3 min scan. The variability of measurements was lower on the Biograph6 than on the HR+. The detectability for the smallest spheres on the Biograph6 was close to that on the HR+. The Biograph has similar performances as the HR+ reference tomograph for the detection and quantification of small hot spots and cold spots.

  18. Monolithic MACS micro resonators

    Science.gov (United States)

    Lehmann-Horn, J. A.; Jacquinot, J.-F.; Ginefri, J. C.; Bonhomme, C.; Sakellariou, D.

    2016-10-01

    Magic Angle Coil Spinning (MACS) aids improving the intrinsically low NMR sensitivity of heterogeneous microscopic samples. We report on the design and testing of a new type of monolithic 2D MACS resonators to overcome known limitations of conventional micro coils. The resonators' conductors were printed on dielectric substrate and tuned without utilizing lumped element capacitors. Self-resonance conditions have been computed by a hybrid FEM-MoM technique. Preliminary results reported here indicate robust mechanical stability, reduced eddy currents heating and negligible susceptibility effects. The gain in B1 /√{ P } is in agreement with the NMR sensitivity enhancement according to the principle of reciprocity. A sensitivity enhancement larger than 3 has been achieved in a monolithic micro resonator inside a standard 4 mm rotor at 500 MHz. These 2D resonators could offer higher performance micro-detection and ease of use of heterogeneous microscopic substances such as biomedical samples, microscopic specimens and thin film materials.

  19. The MONOLITH prototype

    CERN Document Server

    Ambrosio, M; Bencivenni, G; Candela, A M; Chiarini, A; Chignoli, F; De Deo, M; D'Incecco, M; Gerli, S; Giusti, P; Gómez, F; Gustavino, C; Lindozzi, M; Mannocchi, G; Menghetti, H; Morello, C; Murtas, F; Paoluzzi, G; Pilastrini, R; Redaelli, N G; Santoni, M; Sartorelli, G; Terranova, F; Trinchero, G C

    2000-01-01

    MONOLITH (Massive Observatory for Neutrino Oscillation or LImits on THeir existence) is the project of an experiment to study atmospheric neutrino oscillations with a massive magnetized iron detector. The baseline option is a 34 kt iron detector based on the use of about 50000 m/sup 2/ of the glass Resistive Plate Chambers (glass RPCs) developed at the Laboratori Nazionali del Gran Sasso (LNGS). An 8 ton prototype equipped with 23 m/sup 2/ of glass RPC has been realized and tested at the T7-PS beam at CERN. The energy resolution for pions follows a 68%/ square root (E(GeV))+2% law for orthogonally incident particles, in the energy range between 2 and 10 GeV. The time resolution and the tracking capability of the glass RPC are suitable for the MONOLITH experiment. (7 refs).

  20. The AX-PET project Demonstration of a high resolution axial 3D PET

    CERN Document Server

    Bolle, E; Casella, C; Chesi, E; Clinthorne, N; Cochran, E; De Leo, R; Dissertori, G; Djambazov, G; Fanti, V; Honscheid, K; Huh, S; Johnson, I; Joram, C; Kagan, H; Lustermann, W; Meddi, F; Nappi, E; Nessi-Tedaldi, F; Oliver, J F; Pauss, P; Rafecas, M; Renker, D; Rudge, A; Schinzel, D; Schneider, T; Seguinot, J; Smith, S; Solevi, P; Stapnes, S; Weilhammer, P

    2010-01-01

    The AX-PET is a new geometrical concept for a high resolution 3D PET scanner, based on matrices of axially oriented LYSO crystals interleaved by stacks of WLS, both individually read out by G-APDs. A PET demonstrator, based on two detector modules used in coincidence, is currently under construction.

  1. Giardia & Pets

    Science.gov (United States)

    ... body of water Young pets, like puppies and kittens, have a higher risk of illness than adult ... If your pet has persistent diarrhea, seek veterinary care. Diarrhea has different causes and could result in ...

  2. Pet Health

    Science.gov (United States)

    Pets can add fun, companionship and a feeling of safety to your life. Before getting a pet, think carefully about which animal is best for ... is each family member looking for in a pet? Who will take care of it? Does anyone ...

  3. Synthesis of ZSM-5 Monoliths with Hierarchical Porosity

    Institute of Scientific and Technical Information of China (English)

    Tong Yangchuan; Zhao Tianbo; Li Fengyan; Zong Baoning; Wang Yue

    2006-01-01

    A new route to synthesize ZSM-5 monoliths with hierarchical pore structure has been referred to in this stud y. The successful incorporation of the macropores and mesopores within the ZSM-5 structure was achieved through transforming the skeleton of the macroporous silica gel into zeolite ZSM-5 using carbon materials as the transitional template. The ZSM-5 crystal covered part of the macroporous material, and provided micropores to the macroporous silica gel. The structure of carbon monolith was studied after dissolving the silica contained in the carbon/silica composite.

  4. Bioaffinity chromatography on monolithic supports

    NARCIS (Netherlands)

    Tetala, K.K.R.; Beek, van T.A.

    2010-01-01

    Affinity chromatography on monolithic supports is a powerful analytical chemical platform because it allows for fast analyses, small sample volumes, strong enrichment of trace biomarkers and applications in microchips. In this review, the recent research using monolithic materials in the field of bi

  5. Bioaffinity chromatography on monolithic supports

    NARCIS (Netherlands)

    Tetala, K.K.R.; Beek, van T.A.

    2010-01-01

    Affinity chromatography on monolithic supports is a powerful analytical chemical platform because it allows for fast analyses, small sample volumes, strong enrichment of trace biomarkers and applications in microchips. In this review, the recent research using monolithic materials in the field of bi

  6. Design of monoliths through their mechanical properties.

    Science.gov (United States)

    Podgornik, Aleš; Savnik, Aleš; Jančar, Janez; Krajnc, Nika Lendero

    2014-03-14

    Chromatographic monoliths have several interesting properties making them attractive supports for analytics but also for purification, especially of large biomolecules and bioassemblies. Although many of monolith features were thoroughly investigated, there is no data available to predict how monolith mechanical properties affect its chromatographic performance. In this work, we investigated the effect of porosity, pore size and chemical modification on methacrylate monolith compression modulus. While a linear correlation between pore size and compression modulus was found, the effect of porosity was highly exponential. Through these correlations it was concluded that chemical modification affects monolith porosity without changing the monolith skeleton integrity. Mathematical model to describe the change of monolith permeability as a function of monolith compression modulus was derived and successfully validated for monoliths of different geometries and pore sizes. It enables the prediction of pressure drop increase due to monolith compressibility for any monolith structural characteristics, such as geometry, porosity, pore size or mobile phase properties like viscosity or flow rate, based solely on the data of compression modulus and structural data of non-compressed monolith. Furthermore, it enables simple determination of monolith pore size at which monolith compressibility is the smallest and the most robust performance is expected. Data of monolith compression modulus in combination with developed mathematical model can therefore be used for the prediction of monolith permeability during its implementation but also to accelerate the design of novel chromatographic monoliths with desired hydrodynamic properties for particular application.

  7. Porous polymer monolithic col

    Directory of Open Access Journals (Sweden)

    Lydia Terborg

    2015-05-01

    Full Text Available A new approach has been developed for the preparation of mixed-mode stationary phases to separate proteins. The pore surface of monolithic poly(glycidyl methacrylate-co-ethylene dimethacrylate capillary columns was functionalized with thiols and coated with gold nanoparticles. The final mixed mode surface chemistry was formed by attaching, in a single step, alkanethiols, mercaptoalkanoic acids, and their mixtures on the free surface of attached gold nanoparticles. Use of these mixtures allowed fine tuning of the hydrophobic/hydrophilic balance. The amount of attached gold nanoparticles according to thermal gravimetric analysis was 44.8 wt.%. This value together with results of frontal elution enabled calculation of surface coverage with the alkanethiol and mercaptoalkanoic acid ligands. Interestingly, alkanethiols coverage in a range of 4.46–4.51 molecules/nm2 significantly exceeded that of mercaptoalkanoic acids with 2.39–2.45 molecules/nm2. The mixed mode character of these monolithic stationary phases was for the first time demonstrated in the separations of proteins that could be achieved in the same column using gradient elution conditions typical of reverse phase (using gradient of acetonitrile in water and ion exchange chromatographic modes (applying gradient of salt in water, respectively.

  8. Electro-optical effects in porous PET films filled with liquid crystal: new possibilities for fiber optics and THZ applications.

    Science.gov (United States)

    Chopik, A; Pasechnik, S; Semerenko, D; Shmeliova, D; Dubtsov, A; Srivastava, A K; Chigrinov, V

    2014-03-15

    The results of investigation of electro-optical properties of porous polyethylene terephthalate films filled with a nematic liquid crystal (5 CB) are presented. It is established that the optical response of the samples on the applied voltage drastically depends on the frequency range. At low frequencies of applied electrical field (foptical response arises as an impulse of light intensity, which decays for the time essentially shorter than the electric pulse duration. At high frequencies (f>fc) electric field induces an overall change in the light intensity, which is typical for an electro-optical response of a liquid crystal (LC) layer in a conventional "sandwich"-like cell. The dependences of critical frequency fc, threshold voltages, and characteristic times on a pore diameter d were established. The peculiarities of electro-optical effects can be explained in the framework of the approach which connects the variations of light intensity with the corresponding changes of the effective refractive index n(eff) of a composite LC media. The unusual behavior of the electro-optical response at low frequencies is assigned to the orienting action of the specific shear flow typical for electrokinetic phenomena in polar liquids.

  9. 嵌段齐聚物修饰纳米 SiO2对 PET 结晶性能的影响∗%Effect of Nano-SiO2 Modified by Block Oligomer on the Crystallization Property of PET

    Institute of Scientific and Technical Information of China (English)

    孙文建; 郑鹤蛟; 李爱民; 庄洪伟; Laurence A Belfiore; 王瑶; 唐建国; 黄震; 刘继宪; 黄林军; 王彦欣; 焦吉庆; 王薇

    2015-01-01

    采用溶液聚合法在纳米 SiO2表面接枝两种不同性质的齐聚物聚乙二醇(PEG)和聚对苯二甲酸乙二酯低聚物(LMPET),通过 FTIR、1 H-NMR、XPS 和 HR-TEM 对其结构形貌进行表征。采用熔融共混制备 PET 纳米复合材料,并利用 DSC 和 XRD 对改性纳米 SiO2对 PET 结晶性能的影响进行研究。结果表明,LMPET 通过 PEG 成功接枝到 SiO2表面,粒径尺寸为40~50 nm;纳米 SiO2可作为成核剂诱导 PET 的结晶提高结晶速率,当添加量为2%(质量分数)时,结晶温度得到明显提高。%The surface of nano-silica was modified by the oligomer chains PEG and LMPET by solution poly-merization,and its structure morphology was confirmed by FTIR,1 H-NMR,XPS and HR-TEM.PET nanocomposite was prepared via melt blending,the effect on crystallization behavior of PET was studied by DSC and XRD.The re-sults indicated that LMPET was successfully linked onto SiO2 surface through PEG,and the average size of nanopati-cle is about 40-50 nm.It was found that organic silicas could act as nucleating agents in polymer matrix and facilitate the crystallization rate,when the content of modified SiO2 was about 2wt%,the crystallization temperature of PET nanocomposite was improved significantly.

  10. Biobased monoliths for adenovirus purification.

    Science.gov (United States)

    Fernandes, Cláudia S M; Gonçalves, Bianca; Sousa, Margarida; Martins, Duarte L; Barroso, Telma; Pina, Ana Sofia; Peixoto, Cristina; Aguiar-Ricardo, Ana; Roque, A Cecília A

    2015-04-01

    Adenoviruses are important platforms for vaccine development and vectors for gene therapy, increasing the demand for high titers of purified viral preparations. Monoliths are macroporous supports regarded as ideal for the purification of macromolecular complexes, including viral particles. Although common monoliths are based on synthetic polymers as methacrylates, we explored the potential of biopolymers processed by clean technologies to produce monoliths for adenovirus purification. Such an approach enables the development of disposable and biodegradable matrices for bioprocessing. A total of 20 monoliths were produced from different biopolymers (chitosan, agarose, and dextran), employing two distinct temperatures during the freezing process (-20 °C and -80 °C). The morphological and physical properties of the structures were thoroughly characterized. The monoliths presenting higher robustness and permeability rates were further analyzed for the nonspecific binding of Adenovirus serotype 5 (Ad5) preparations. The matrices presenting lower nonspecific Ad5 binding were further functionalized with quaternary amine anion-exchange ligand glycidyltrimethylammonium chloride hydrochloride by two distinct methods, and their performance toward Ad5 purification was assessed. The monolith composed of chitosan and poly(vinyl) alcohol (50:50) prepared at -80 °C allowed 100% recovery of Ad5 particles bound to the support. This is the first report of the successful purification of adenovirus using monoliths obtained from biopolymers processed by clean technologies.

  11. Monolithic microchannel heatsink

    Science.gov (United States)

    Benett, William J.; Beach, Raymond J.; Ciarlo, Dino R.

    1996-01-01

    A silicon wafer has slots sawn in it that allow diode laser bars to be mounted in contact with the silicon. Microchannels are etched into the back of the wafer to provide cooling of the diode bars. To facilitate getting the channels close to the diode bars, the channels are rotated from an angle perpendicular to the diode bars which allows increased penetration between the mounted diode bars. This invention enables the fabrication of monolithic silicon microchannel heatsinks for laser diodes. The heatsinks have low thermal resistance because of the close proximity of the microchannels to the laser diode being cooled. This allows high average power operation of two-dimensional laser diode arrays that have a high density of laser diode bars and therefore high optical power density.

  12. Experimental Validation of an Efficient Fan-Beam Calibration Procedure for k -Nearest Neighbor Position Estimation in Monolithic Scintillator Detectors

    NARCIS (Netherlands)

    Borghi, G.; Tabacchini, V.; Seifert, S.; Schaart, D.R.

    2015-01-01

    Monolithic scintillator detectors can achieve excellent spatial resolution and coincidence resolving time. However, their practical use for positron emission tomography (PET) and other applications in the medical imaging field is still limited due to drawbacks of the different methods used to

  13. Pet Allergy Quiz

    Science.gov (United States)

    ... Treatments ▸ Allergies ▸ Pet Allergy ▸ Pet Allergy Quiz Share | Pet Allergy Quiz More than half of U.S. households ... cat family. Yet, millions of people suffer from pet allergies. Take this quiz to test your knowledge ...

  14. Development of scintillation materials for PET scanners

    CERN Document Server

    Korzhik, Mikhail; Annenkov, Alexander N; Borissevitch, Andrei; Dossovitski, Alexei; Missevitch, Oleg; Lecoq, Paul

    2007-01-01

    The growing demand on PET methodology for a variety of applications ranging from clinical use to fundamental studies triggers research and development of PET scanners providing better spatial resolution and sensitivity. These efforts are primarily focused on the development of advanced PET detector solutions and on the developments of new scintillation materials as well. However Lu containing scintillation materials introduced in the last century such as LSO, LYSO, LuAP, LuYAP crystals still remain the best PET species in spite of the recent developments of bright, fast but relatively low density lanthanum bromide scintillators. At the same time Lu based materials have several drawbacks which are high temperature of crystallization and relatively high cost compared to alkali-halide scintillation materials. Here we describe recent results in the development of new scintillation materials for PET application.

  15. Positron Emission Tomography (PET)

    Energy Technology Data Exchange (ETDEWEB)

    Welch, M.J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs.

  16. Positron Emission Tomography (PET)

    Science.gov (United States)

    Welch, M. J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET.

  17. Processing and characterization of extruded PET and its r-PET and MWCNT nanocomposite thin films by spin coating

    Indian Academy of Sciences (India)

    Arvind R Singh; Vineeta D Deshpande

    2016-02-01

    The objective of the present study was basic understanding of the formation of thin film morphology by spin coating using reorganized polyethylene terephthalate (r-PET) and multiwalled carbon nanotubes (MWCNTs) as fillers in PET. A study of the correlation between physical properties of the PET films and its surface morphology was carried out using atomic force microscopy-based power spectral density (PSD) analysis. No significant work of surface analysis, using PSD of thin films of PET has been reported till date. Dilute solution of PET, PET with 3 wt% (r-PET) and PET with 3 wt% (2 wt% r-PET + 1 wt% MWCNT) filler were prepared using trifluoroacetic acid (TFA) as a solvent and thin films were fabricated on glass substrate by the optimized spin coating technique. Preparation of r-PET and r-PET+ MWCNT fillers was obtained by the precipitation method using TFA as a solvent and acetone as an antisolvent. The samples before spin coating were extruded and for comparison, a film of non-extruded PET was also prepared. Structural studies by Fourier transform infrared and X-ray diffraction show higher degree of crystallinity in r-PET and decrease in chain entanglements. Owing to the crystallizing behaviour of r-PET, it allows better dispersion of MWCNT in the polymer matrix as compared with PET. The samples with fillers of MWCNT show more compact and unique mesh-like globular structure, indicating application for electromagnetic shielding foams and fibres.

  18. Sustainable Engineering and Improved Recycling of PET for High-Value Applications: Transforming Linear PET to Lightly Branched PET with a Novel, Scalable Process

    Science.gov (United States)

    Pierre, Cynthia; Torkelson, John

    2009-03-01

    A major challenge for the most effective recycling of poly(ethylene terephthalate) concerns the fact that initial melt processing of PET into a product leads to substantial degradation of molecular weight. Thus, recycled PET has insufficient melt viscosity for reuse in high-value applications such as melt-blowing of PET bottles. Academic and industrial research has tried to remedy this situation by synthesis and use of ``chain extenders'' that can lead to branched PET (with higher melt viscosity than the linear recycled PET) via condensation reactions with functional groups on the PET. Here we show that simple processing of PET via solid-state shear pulverization (SSSP) leads to enhanced PET melt viscosity without need for chemical additives. We hypothesize that this branching results from low levels of chain scission accompanying SSSP, leading to formation of polymeric radicals that participate in chain transfer and combination reactions with other PET chains and thereby to in situ branch formation. The pulverized PET exhibits vastly enhanced crystallization kinetics, eliminating the need to employ cold crystallization to achieve maximum PET crystallinity. Results of SSSP processing of PET will be compared to results obtained with poly(butylene terephthalate).

  19. Study of a high-resolution, 3D positioning cadmium zinc telluride detector for PET

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Y; Levin, C S [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M, E-mail: cslevin@stanford.edu [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States)

    2011-03-21

    This paper investigates the performance of 1 mm resolution cadmium zinc telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm x 40 mm x 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06 {+-} 0.39% at 511 keV throughout most of the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44 {+-} 0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78 {+-} 0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes-as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system.

  20. Study of a high-resolution, 3D positioning cadmium zinc telluride detector for PET

    Science.gov (United States)

    Gu, Y.; Matteson, J. L.; Skelton, R. T.; Deal, A. C.; Stephan, E. A.; Duttweiler, F.; Gasaway, T. M.; Levin, C. S.

    2011-03-01

    This paper investigates the performance of 1 mm resolution cadmium zinc telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06 ± 0.39% at 511 keV throughout most of the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44 ± 0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78 ± 0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes—as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system.

  1. Study of a high-resolution, 3-D positioning cadmium zinc telluride detector for PET

    Science.gov (United States)

    Gu, Y; Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

    2011-01-01

    This paper investigates the performance of 1 mm resolution Cadmium Zinc Telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3-D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06±0.39% at 511 keV throughout most the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44±0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78±0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes – as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system. PMID:21335649

  2. In situ Fabrication of Monolithic Copper Azide

    Science.gov (United States)

    Li, Bing; Li, Mingyu; Zeng, Qingxuan; Wu, Xingyu

    2016-04-01

    Fabrication and characterization of monolithic copper azide were performed. The monolithic nanoporous copper (NPC) with interconnected pores and nanoparticles was prepared by decomposition and sintering of the ultrafine copper oxalate. The preferable monolithic NPC can be obtained through decomposition and sintering at 400°C for 30 min. Then, the available monolithic NPC was in situ reacted with the gaseous HN3 for 24 h and the monolithic NPC was transformed into monolithic copper azide. Additionally, the copper particles prepared by electrodeposition were also reacted with the gaseous HN3 under uniform conditions as a comparison. The fabricated monolithic copper azide was characterized by Fourier transform infrared (FTIR), inductively coupled plasma-optical emission spectrometry (ICP-OES), and differential scanning calorimetry (DSC).

  3. Senior Pets

    Science.gov (United States)

    ... by Animal/Species Browse by Topic Browse by Discipline Resources Tools for K-12 Educators You are here: Home | Public Resources | Pet ... to 6 years of age. Contrary to popular belief, dogs do not age at a rate of 7 human years for each year in dog years. Age ...

  4. Pet Therapy.

    Science.gov (United States)

    Kavanagh, Kim

    1994-01-01

    This resource guide presents information on a variety of ways that animals can be used as a therapeutic modality with people having disabilities. Aspects addressed include: pet ownership and selection criteria; dogs (including service dogs, hearing/signal dogs, seeing leader dogs, and social/specialty dogs); horseriding for both therapy and fun;…

  5. Solid state polymerization: its action on thermal and rheological properties of PET/PC reactive blends

    Directory of Open Access Journals (Sweden)

    Luis C. Mendes

    2013-01-01

    Full Text Available The solid state polymerization (SSP of PET/PC reactive extrusion blends - with and without cobalt catalyst - at different polymer ratios was studied. Thermal and rheological evaluations were performed. DSC results showed changes in the PET's Tg, Tch, Tm and Xc.. The melt flow rate (MFR decreased for PET and the blends. The intrinsic viscosity increased. The variation in calorimetric and rheological properties might be attributed to the PET's chain extension reactions - esterification and transesterification. These reactions led to an increase in the PET's molar mass, consequently shifting the PET's Tg to lower temperature and PET's crystallization, besides reducing the blend miscibility and flowability.

  6. Monolithic Fuel Fabrication Process Development

    Energy Technology Data Exchange (ETDEWEB)

    C. R. Clark; N. P. Hallinan; J. F. Jue; D. D. Keiser; J. M. Wight

    2006-05-01

    The pursuit of a high uranium density research reactor fuel plate has led to monolithic fuel, which possesses the greatest possible uranium density in the fuel region. Process developments in fabrication development include friction stir welding tool geometry and cooling improvements and a reduction in the length of time required to complete the transient liquid phase bonding process. Annealing effects on the microstructures of the U-10Mo foil and friction stir welded aluminum 6061 cladding are also examined.

  7. Pressure drop in CIM disk monolithic columns.

    Science.gov (United States)

    Mihelic, Igor; Nemec, Damjan; Podgornik, Ales; Koloini, Tine

    2005-02-11

    Pressure drop analysis in commercial CIM disk monolithic columns is presented. Experimental measurements of pressure drop are compared to hydrodynamic models usually employed for prediction of pressure drop in packed beds, e.g. free surface model and capillary model applying hydraulic radius concept. However, the comparison between pressure drop in monolith and adequate packed bed give unexpected results. Pressure drop in a CIM disk monolithic column is approximately 50% lower than in an adequate packed bed of spheres having the same hydraulic radius as CIM disk monolith; meaning they both have the same porosity and the same specific surface area. This phenomenon seems to be a consequence of the monolithic porous structure which is quite different in terms of the pore size distribution and parallel pore nonuniformity compared to the one in conventional packed beds. The number of self-similar levels for the CIM monoliths was estimated to be between 1.03 and 2.75.

  8. Graphene-supported metal oxide monolith

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Baumann, Theodore F.; Biener, Juergen; Biener, Monika A.; Wang, Yinmin; Ye, Jianchao; Tylski, Elijah

    2017-01-10

    A composition comprising at least one graphene-supported metal oxide monolith, said monolith comprising a three-dimensional structure of graphene sheets crosslinked by covalent carbon bonds, wherein the graphene sheets are coated by at least one metal oxide such as iron oxide or titanium oxide. Also provided is an electrode comprising the aforementioned graphene-supported metal oxide monolith, wherein the electrode can be substantially free of any carbon-black and substantially free of any binder.

  9. Graphene-supported metal oxide monolith

    Science.gov (United States)

    Worsley, Marcus A.; Baumann, Theodore F.; Biener, Juergen; Biener, Monika A.; Wang, Yinmin; Ye, Jianchao; Tylski, Elijah

    2017-01-10

    A composition comprising at least one graphene-supported metal oxide monolith, said monolith comprising a three-dimensional structure of graphene sheets crosslinked by covalent carbon bonds, wherein the graphene sheets are coated by at least one metal oxide such as iron oxide or titanium oxide. Also provided is an electrode comprising the aforementioned graphene-supported metal oxide monolith, wherein the electrode can be substantially free of any carbon-black and substantially free of any binder.

  10. Pet Disaster Preparedness

    Science.gov (United States)

    ... Safety Checklist – Arabic Pets and Disaster Safety Checklist – Chinese Pets and Disaster Safety Checklist – French Pets and ... Cross serves in the US, its territories and military installations around the world. Please try again. Your ...

  11. Your Pet's Medications

    Science.gov (United States)

    ... Care Animal Welfare Veterinary Careers Public Health Your Pet's Medications When your pet has a medical condition, ... authorized. What you can do to keep your pet safe When the medication is prescribed Let your ...

  12. Preclinical positron emission tomography scanner based on a monolithic annulus of scintillator: initial design study.

    Science.gov (United States)

    Stolin, Alexander V; Martone, Peter F; Jaliparthi, Gangadhar; Raylman, Raymond R

    2017-01-01

    Positron emission tomography (PET) scanners designed for imaging of small animals have transformed translational research by reducing the necessity to invasively monitor physiology and disease progression. Virtually all of these scanners are based on the use of pixelated detector modules arranged in rings. This design, while generally successful, has some limitations. Specifically, use of discrete detector modules to construct PET scanners reduces detection sensitivity and can introduce artifacts in reconstructed images, requiring the use of correction methods. To address these challenges, and facilitate measurement of photon depth-of-interaction in the detector, we investigated a small animal PET scanner (called AnnPET) based on a monolithic annulus of scintillator. The scanner was created by placing 12 flat facets around the outer surface of the scintillator to accommodate placement of silicon photomultiplier arrays. Its performance characteristics were explored using Monte Carlo simulations and sections of the NEMA NU4-2008 protocol. Results from this study revealed that AnnPET's reconstructed spatial resolution is predicted to be [Formula: see text] full width at half maximum in the radial, tangential, and axial directions. Peak detection sensitivity is predicted to be 10.1%. Images of simulated phantoms (mini-hot rod and mouse whole body) yielded promising results, indicating the potential of this system for enhancing PET imaging of small animals.

  13. Structures and magnetism of mono-palladium and mono-platinum doped Au25(PET)18 nanoclusters.

    Science.gov (United States)

    Tian, Shubo; Liao, Lingwen; Yuan, Jinyun; Yao, Chuanhao; Chen, Jishi; Yang, Jinlong; Wu, Zhikun

    2016-08-01

    Herein we report three important results of widespread interest, which are (1) the crystal structure of [Au24Pt(PET)18](0), (2) the crystal structure of [Au24Pd(PET)18](0) and (3) the main source of magnetism in [Au25(PET)18](0).

  14. American Pet Culture

    Institute of Scientific and Technical Information of China (English)

    海焰

    2007-01-01

    In America you can find dogs,cats, horses,monkeys, snakes and even pigs in almost every family.They are their pets.Americans love pets and look on them as a part of the family.Sometimes pet owners dress their pets in fashionable clothes.They even buy toys for their pets.Americans love their pets as their children, sometimes even better.

  15. Development of a PET Scanner for Simultaneously Imaging Small Animals with MRI and PET

    Directory of Open Access Journals (Sweden)

    Christopher J Thompson

    2014-08-01

    Full Text Available Recently, positron emission tomography (PET is playing an increasingly important role in the diagnosis and staging of cancer. Combined PET and X-ray computed tomography (PET-CT scanners are now the modality of choice in cancer treatment planning. More recently, the combination of PET and magnetic resonance imaging (MRI is being explored in many sites. Combining PET and MRI has presented many challenges since the photo-multiplier tubes (PMT in PET do not function in high magnetic fields, and conventional PET detectors distort MRI images. Solid state light sensors like avalanche photo-diodes (APDs and more recently silicon photo-multipliers (SiPMs are much less sensitive to magnetic fields thus easing the compatibility issues. This paper presents the results of a group of Canadian scientists who are developing a PET detector ring which fits inside a high field small animal MRI scanner with the goal of providing simultaneous PET and MRI images of small rodents used in pre-clinical medical research. We discuss the evolution of both the crystal blocks (which detect annihilation photons from positron decay and the SiPM array performance in the last four years which together combine to deliver significant system performance in terms of speed, energy and timing resolution.

  16. Dedicated brain PET system of PET/MR for brain research

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Li; Liu, Yaqiang; Ma, Tianyu; Wang, Shi; Wei, Qingyang; Xu, Tianpeng [Institute of Medical Physics, Department of Engineering Physics, Tsinghua University, Beijing (China)

    2015-05-18

    This work is to replace PET ring in human brain PET/MR system with a dedicated wearable PET insert, aimed at improving both patient feasibility and system performance for brain imaging. The designed PET/MR system includes two parts: the inside parts, including a radio frequency (RF) coil and PET ring, are mounted on patient’s head, and the outside part, a MR imager, is dependent of patient. The RF coil is the innermost layer, surrounded by an outer PET-ring layer. They are supported by a MRcompatible structure. And both RF coil and PET detectors are placed inside a standard clinical 3-T MR imager. From the design of the system we can infer that some advantages can be achieved. First, high sensitivity will be achieved with the same amount crystals as the PET ring is more close to region-of-interest area, at a reduced cost. Second, by using a 2-layer depth of interaction (DOI) detector, the parallax effect can be minimized. The resolution will benefit from short positron range caused by magnetic field and smaller ring diameter will also reduce the effect of non-collinearity. Thirdly, as the PET ring is mounted on head, impact of patient motion will be reduced.

  17. Pet Problems at Home: Pet Problems in the Community.

    Science.gov (United States)

    Soltow, Willow

    1984-01-01

    Discusses problems of pets in the community, examining the community's role related to disruptive pets and pet overpopulation. Also discusses pet problems at home, offering advice on selecting a pet, meeting a pet's needs, and disciplining pets. Includes a list of books, films/filmstrips, teaching materials, and various instructional strategies.…

  18. Pet Problems at Home: Pet Problems in the Community.

    Science.gov (United States)

    Soltow, Willow

    1984-01-01

    Discusses problems of pets in the community, examining the community's role related to disruptive pets and pet overpopulation. Also discusses pet problems at home, offering advice on selecting a pet, meeting a pet's needs, and disciplining pets. Includes a list of books, films/filmstrips, teaching materials, and various instructional strategies.…

  19. Monolithically integrated absolute frequency comb laser system

    Energy Technology Data Exchange (ETDEWEB)

    Wanke, Michael C.

    2016-07-12

    Rather than down-convert optical frequencies, a QCL laser system directly generates a THz frequency comb in a compact monolithically integrated chip that can be locked to an absolute frequency without the need of a frequency-comb synthesizer. The monolithic, absolute frequency comb can provide a THz frequency reference and tool for high-resolution broad band spectroscopy.

  20. Nanosecond monolithic CMOS readout cell

    Science.gov (United States)

    Souchkov, Vitali V.

    2004-08-24

    A pulse shaper is implemented in monolithic CMOS with a delay unit formed of a unity gain buffer. The shaper is formed of a difference amplifier having one input connected directly to an input signal and a second input connected to a delayed input signal through the buffer. An elementary cell is based on the pulse shaper and a timing circuit which gates the output of an integrator connected to the pulse shaper output. A detector readout system is formed of a plurality of elementary cells, each connected to a pixel of a pixel array, or to a microstrip of a plurality of microstrips, or to a detector segment.

  1. Compact monolithic capacitive discharge unit

    Science.gov (United States)

    Roesler, Alexander W.; Vernon, George E.; Hoke, Darren A.; De Marquis, Virginia K.; Harris, Steven M.

    2007-06-26

    A compact monolithic capacitive discharge unit (CDU) is disclosed in which a thyristor switch and a flyback charging circuit are both sandwiched about a ceramic energy storage capacitor. The result is a compact rugged assembly which provides a low-inductance current discharge path. The flyback charging circuit preferably includes a low-temperature co-fired ceramic transformer. The CDU can further include one or more ceramic substrates for enclosing the thyristor switch and for holding various passive components used in the flyback charging circuit. A load such as a detonator can also be attached directly to the CDU.

  2. Comparison of FDG PET and positron coincidence detection imaging using a dual-head gamma camera with 5/8-inch NaI(Tl) crystals in patients with suspected body malignancies.

    Science.gov (United States)

    Boren, E L; Delbeke, D; Patton, J A; Sandler, M P

    1999-04-01

    The purpose of this study was to compare the diagnostic accuracy of fluorine-18 fluorodeoxyglucose (FDG) images obtained with (a) a dual-head coincidence gamma camera (DHC) equipped with 5/8-inch-thick NaI(Tl) crystals and parallel slit collimators and (b) a dedicated positron emission tomograph (PET) in a series of 28 patients with known or suspected malignancies. Twenty-eight patients with known or suspected malignancies underwent whole-body FDG PET imaging (Siemens, ECAT 933) after injection of approximately 10 mCi of 18F-FDG. FDG DHC images were then acquired for 30 min over the regions of interest using a dual-head gamma camera (VariCam, Elscint). The images were reconstructed in the normal mode, using photopeak/photopeak, photopeak/Compton, and Compton/photopeak coincidence events. FDG PET imaging found 45 lesions ranging in size from 1 cm to 7 cm in 28 patients. FDG DHC imaging detected 35/45 (78%) of these lesions. Among the ten lesions not seen with FDG DHC imaging, eight were less than 1.5 cm in size, and two were located centrally within the abdomen suffering from marked attenuation effects. The lesions were classified into three categories: thorax (n=24), liver (n=12), and extrahepatic abdominal (n=9). FDG DHC imaging identified 100% of lesions above 1.5 cm in the thorax group and 78% of those below 1.5 cm, for an overall total of 83%. FDG DHC imaging identified 100% of lesions above 1.5 cm, in the liver and 43% of lesions below 1.5 cm, for an overall total of 67%. FDG DHC imaging identified 78% of lesions above 1.5 cm in the extrahepatic abdominal group. There were no lesions below 1.5 cm in this group. FDG coincidence imaging using a dual-head gamma camera detected 90% of lesions greater than 1.5 cm. These data suggest that DHC imaging can be used clinically in well-defined diagnostic situations to differentiate benign from malignant lesions.

  3. Monolithic stabilized Yb-fiber All-PM laser directly delivering nJ-level femtosecond pulses

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

    2008-01-01

    We present a monolithic, self-starting, all-PM, stabilized Yb-fiber laser, pulse-compressed in a hollow-core PM photonic crystal fiber, providing the 370 fs pulses of 4 nJ energy with high mode quality.......We present a monolithic, self-starting, all-PM, stabilized Yb-fiber laser, pulse-compressed in a hollow-core PM photonic crystal fiber, providing the 370 fs pulses of 4 nJ energy with high mode quality....

  4. A Laue–Bragg monolithic beam splitter for efficient X-ray 2-beam imaging

    Energy Technology Data Exchange (ETDEWEB)

    Oberta, P., E-mail: peter.oberta@rigaku.com [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Na Slovance 2, CZ-18221 Praha 8 (Czech Republic); Mokso, R. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

    2013-03-01

    Newly emerging techniques for probing matter simultaneously by two spatially and angularly separated X-ray beams require efficient and versatile beam splitting. We present a Laue–Bragg monolithic crystal beam splitter in the form of an L-shaped monolithic Si crystal. By simultaneous Laue and Bragg diffractions the X-ray beam is split into a transmitted polychromatic and a diffracted monochromatic branch with a spatial separation of tens of millimeters. The energy spectrum of the transmitted branch can be tuned via diffraction on a second crystal re-creating a beam intersection on the sample. We propose three multi-modal imaging setups exploiting the large angular separation of the two intersecting beams provided by the proposed optics. Photon efficiency and dual-energy operation are the main assets of our scheme as compared to other existing setups. The theoretical description for an energy range between 10 keV and 30 keV was developed.

  5. Microfluidic devices and methods including porous polymer monoliths

    Science.gov (United States)

    Hatch, Anson V; Sommer, Gregory J; Singh, Anup K; Wang, Ying-Chih; Abhyankar, Vinay V

    2014-04-22

    Microfluidic devices and methods including porous polymer monoliths are described. Polymerization techniques may be used to generate porous polymer monoliths having pores defined by a liquid component of a fluid mixture. The fluid mixture may contain iniferters and the resulting porous polymer monolith may include surfaces terminated with iniferter species. Capture molecules may then be grafted to the monolith pores.

  6. Fabrication of Porous Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate Monoliths via Thermally Induced Phase Separation

    Directory of Open Access Journals (Sweden)

    Takashi Tsujimoto

    2016-02-01

    Full Text Available This study deals with the fabrication of biodegradable porous materials from bacterial polyester, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB3HHx, via thermally induced phase separation. P3HB3HHx monoliths with topological porous structure were prepared by dissolution of P3HB3HHx in dimethyl sulfoxide (DMSO at 85 °C and subsequent quenching. The microstructure of the resulting P3HB3HHx monoliths was changed by the P3HB3HHx concentration of the polymer solution. Differential scanning calorimetry and polarized optical microscope analysis revealed that the P3HB3HHx monoliths crystallized during phase separation and the subsequent aging. The mechanical properties, such as compression modulus and stress, of the monoliths depended on the 3-hydroxyhexanoate content of P3HB3HHx. Furthermore, the P3HB3HHx monolith absorbed linseed oil in preference to water in a plant oil–water mixture. In combination with the biodegradable character of P3HB3HHx, the present study is expected to contribute to the development of bio-based materials.

  7. PET/CT: underlying physics, instrumentation, and advances.

    Science.gov (United States)

    Torres Espallardo, I

    2017-01-12

    Since it was first introduced, the main goal of PET/CT has been to provide both PET and CT images with high clinical quality and to present them to radiologists and specialists in nuclear medicine as a fused, perfectly aligned image. The use of fused PET and CT images quickly became routine in clinical practice, showing the great potential of these hybrid scanners. Thanks to this success, manufacturers have gone beyond considering CT as a mere attenuation corrector for PET, concentrating instead on design high performance PET and CT scanners with more interesting features. Since the first commercial PET/CT scanner became available in 2001, both the PET component and the CT component have improved immensely. In the case of PET, faster scintillation crystals with high stopping power such as LYSO crystals have enabled more sensitive devices to be built, making it possible to reduce the number of undesired coincidence events and to use time of flight (TOF) techniques. All these advances have improved lesion detection, especially in situations with very noisy backgrounds. Iterative reconstruction methods, together with the corrections carried out during the reconstruction and the use of the point-spread function, have improved image quality. In parallel, CT instrumentation has also improved significantly, and 64- and 128-row detectors have been incorporated into the most modern PET/CT scanners. This makes it possible to obtain high quality diagnostic anatomic images in a few seconds that both enable the correction of PET attenuation and provide information for diagnosis. Furthermore, nowadays nearly all PET/CT scanners have a system that modulates the dose of radiation that the patient is exposed to in the CT study in function of the region scanned. This article reviews the underlying physics of PET and CT imaging separately, describes the changes in the instrumentation and standard protocols in a combined PET/CT system, and finally points out the most important

  8. PeneloPET, a Monte Carlo PET simulation tool based on PENELOPE: features and validation

    Energy Technology Data Exchange (ETDEWEB)

    Espana, S; Herraiz, J L; Vicente, E; Udias, J M [Grupo de Fisica Nuclear, Departmento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid (Spain); Vaquero, J J; Desco, M [Unidad de Medicina y CirugIa Experimental, Hospital General Universitario Gregorio Maranon, Madrid (Spain)], E-mail: jose@nuc2.fis.ucm.es

    2009-03-21

    Monte Carlo simulations play an important role in positron emission tomography (PET) imaging, as an essential tool for the research and development of new scanners and for advanced image reconstruction. PeneloPET, a PET-dedicated Monte Carlo tool, is presented and validated in this work. PeneloPET is based on PENELOPE, a Monte Carlo code for the simulation of the transport in matter of electrons, positrons and photons, with energies from a few hundred eV to 1 GeV. PENELOPE is robust, fast and very accurate, but it may be unfriendly to people not acquainted with the FORTRAN programming language. PeneloPET is an easy-to-use application which allows comprehensive simulations of PET systems within PENELOPE. Complex and realistic simulations can be set by modifying a few simple input text files. Different levels of output data are available for analysis, from sinogram and lines-of-response (LORs) histogramming to fully detailed list mode. These data can be further exploited with the preferred programming language, including ROOT. PeneloPET simulates PET systems based on crystal array blocks coupled to photodetectors and allows the user to define radioactive sources, detectors, shielding and other parts of the scanner. The acquisition chain is simulated in high level detail; for instance, the electronic processing can include pile-up rejection mechanisms and time stamping of events, if desired. This paper describes PeneloPET and shows the results of extensive validations and comparisons of simulations against real measurements from commercial acquisition systems. PeneloPET is being extensively employed to improve the image quality of commercial PET systems and for the development of new ones.

  9. Monolithic Continuous-Flow Bioreactors

    Science.gov (United States)

    Stephanopoulos, Gregory; Kornfield, Julia A.; Voecks, Gerald A.

    1993-01-01

    Monolithic ceramic matrices containing many small flow passages useful as continuous-flow bioreactors. Ceramic matrix containing passages made by extruding and firing suitable ceramic. Pores in matrix provide attachment medium for film of cells and allow free movement of solution. Material one not toxic to micro-organisms grown in reactor. In reactor, liquid nutrients flow over, and liquid reaction products flow from, cell culture immobilized in one set of channels while oxygen flows to, and gaseous reaction products flow from, culture in adjacent set of passages. Cells live on inner surfaces containing flowing nutrient and in pores of walls of passages. Ready access to nutrients and oxygen in channels. They generate continuous high yield characteristic of immobilized cells, without large expenditure of energy otherwise incurred if necessary to pump nutrient solution through dense biomass as in bioreactors of other types.

  10. Anisotropically structured magnetic aerogel monoliths

    Science.gov (United States)

    Heiligtag, Florian J.; Airaghi Leccardi, Marta J. I.; Erdem, Derya; Süess, Martin J.; Niederberger, Markus

    2014-10-01

    Texturing of magnetic ceramics and composites by aligning and fixing of colloidal particles in a magnetic field is a powerful strategy to induce anisotropic chemical, physical and especially mechanical properties into bulk materials. If porosity could be introduced, anisotropically structured magnetic materials would be the perfect supports for magnetic separations in biotechnology or for magnetic field-assisted chemical reactions. Aerogels, combining high porosity with nanoscale structural features, offer an exceptionally large surface area, but they are difficult to magnetically texture. Here we present the preparation of anatase-magnetite aerogel monoliths via the assembly of preformed nanocrystallites. Different approaches are proposed to produce macroscopic bodies with gradient-like magnetic segmentation or with strongly anisotropic magnetic texture.Texturing of magnetic ceramics and composites by aligning and fixing of colloidal particles in a magnetic field is a powerful strategy to induce anisotropic chemical, physical and especially mechanical properties into bulk materials. If porosity could be introduced, anisotropically structured magnetic materials would be the perfect supports for magnetic separations in biotechnology or for magnetic field-assisted chemical reactions. Aerogels, combining high porosity with nanoscale structural features, offer an exceptionally large surface area, but they are difficult to magnetically texture. Here we present the preparation of anatase-magnetite aerogel monoliths via the assembly of preformed nanocrystallites. Different approaches are proposed to produce macroscopic bodies with gradient-like magnetic segmentation or with strongly anisotropic magnetic texture. Electronic supplementary information (ESI) available: Digital photographs of dispersions and gels with different water-to-ethanol ratios; magnetic measurements of an anatase aerogel containing 0.25 mol% Fe3O4 nanoparticles; XRD patterns of the iron oxide and

  11. Monolithic cells for solar fuels.

    Science.gov (United States)

    Rongé, Jan; Bosserez, Tom; Martel, David; Nervi, Carlo; Boarino, Luca; Taulelle, Francis; Decher, Gero; Bordiga, Silvia; Martens, Johan A

    2014-12-07

    Hybrid energy generation models based on a variety of alternative energy supply technologies are considered the best way to cope with the depletion of fossil energy resources and to limit global warming. One of the currently missing technologies is the mimic of natural photosynthesis to convert carbon dioxide and water into chemical fuel using sunlight. This idea has been around for decades, but artificial photosynthesis of organic molecules is still far away from providing real-world solutions. The scientific challenge is to perform in an efficient way the multi-electron transfer reactions of water oxidation and carbon dioxide reduction using holes and single electrons generated in an illuminated semiconductor. In this tutorial review the design of photoelectrochemical (PEC) cells that combine solar water oxidation and CO2 reduction is discussed. In such PEC cells simultaneous transport and efficient use of light, electrons, protons and molecules has to be managed. It is explained how efficiency can be gained by compartmentalisation of the water oxidation and CO2 reduction processes by proton exchange membranes, and monolithic concepts of artificial leaves and solar membranes are presented. Besides transferring protons from the anode to the cathode compartment the membrane serves as a molecular barrier material to prevent cross-over of oxygen and fuel molecules. Innovative nano-organized multimaterials will be needed to realise practical artificial photosynthesis devices. This review provides an overview of synthesis techniques which could be used to realise monolithic multifunctional membrane-electrode assemblies, such as Layer-by-Layer (LbL) deposition, Atomic Layer Deposition (ALD), and porous silicon (porSi) engineering. Advances in modelling approaches, electrochemical techniques and in situ spectroscopies to characterise overall PEC cell performance are discussed.

  12. Pets and the immunocompromised person

    Science.gov (United States)

    AIDS patients and pets; Bone marrow transplant patients and pets; Chemotherapy patients and pets ... systems may be advised to give up their pets to avoid getting diseases from the animals. People ...

  13. The MiniPET: a didactic PET system

    Science.gov (United States)

    Pedro, R.; Silva, J.; Gurriana, L.; Silva, J. M.; Maio, A.; Soares Augusto, J.

    2013-03-01

    The MiniPET project aims to design and build a small PET system. It consists of two 4 × 4 matrices of 16 LYSO scintillator crystals and two PMTs with 16 channels resulting in a low cost system with the essential functionality of a clinical PET instrument. It is designed to illustrate the physics of the PET technique and to provide a didactic platform for the training of students and nuclear imaging professionals as well as for scientific outreach. The PET modules can be configured to test for the coincidence of 511 keV gamma rays. The model has a flexible mechanical setup [1] and can simulate 14 diferent ring geometries, from a configuration with as few as 18 detectors per ring (ring radius phi=51 mm), up to a geometry with 70 detectors per ring (phi=200 mm). A second version of the electronic system [2] allowed measurement and recording of the energy deposited in 4 detector channels by photons from a 137Cs radioactive source and by photons resulting of the annihilation of positrons from a 22Na radioactive source. These energy spectra are used for detector performance studies, as well as angular dependency studies. In this paper, the mechanical setup, the front-end high-speed analog electronics, the digital acquisition and control electronics implemented in a FPGA, as well as the data-transfer interface between the FPGA board and a host PC are described. Recent preliminary results obtained with the 4 active channels in the prototype are also presented.

  14. Trends in PET imaging

    Energy Technology Data Exchange (ETDEWEB)

    Moses, William W.

    2000-11-01

    Positron Emission Tomography (PET) imaging is a well established method for obtaining information on the status of certain organs within the human body or in animals. This paper presents an overview of recent trends PET instrumentation. Significant effort is being expended to develop new PET detector modules, especially those capable of measuring depth of interaction. This is aided by recent advances in scintillator and pixellated photodetector technology. The other significant area of effort is development of special purpose PET cameras (such as for imaging breast cancer or small animals) or cameras that have the ability to image in more than one modality (such as PET / SPECT or PET / X-Ray CT).

  15. Monolithic Time Delay Integrated APD Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of the proposed program by Epitaxial Technologies is to develop monolithic time delay integrated avalanche photodiode (APD) arrays with sensitivity...

  16. Monolithic multinozzle emitters for nanoelectrospray mass spectrometry

    Science.gov (United States)

    Wang, Daojing; Yang, Peidong; Kim, Woong; Fan, Rong

    2011-09-20

    Novel and significantly simplified procedures for fabrication of fully integrated nanoelectrospray emitters have been described. For nanofabricated monolithic multinozzle emitters (NM.sup.2 emitters), a bottom up approach using silicon nanowires on a silicon sliver is used. For microfabricated monolithic multinozzle emitters (M.sup.3 emitters), a top down approach using MEMS techniques on silicon wafers is used. The emitters have performance comparable to that of commercially-available silica capillary emitters for nanoelectrospray mass spectrometry.

  17. Activated Carbon Fiber Monoliths as Supercapacitor Electrodes

    Directory of Open Access Journals (Sweden)

    Gelines Moreno-Fernandez

    2017-01-01

    Full Text Available Activated carbon fibers (ACF are interesting candidates for electrodes in electrochemical energy storage devices; however, one major drawback for practical application is their low density. In the present work, monoliths were synthesized from two different ACFs, reaching 3 times higher densities than the original ACFs’ apparent densities. The porosity of the monoliths was only slightly decreased with respect to the pristine ACFs, the employed PVDC binder developing additional porosity upon carbonization. The ACF monoliths are essentially microporous and reach BET surface areas of up to 1838 m2 g−1. SEM analysis reveals that the ACFs are well embedded into the monolith structure and that their length was significantly reduced due to the monolith preparation process. The carbonized monoliths were studied as supercapacitor electrodes in two- and three-electrode cells having 2 M H2SO4 as electrolyte. Maximum capacitances of around 200 F g−1 were reached. The results confirm that the capacitance of the bisulfate anions essentially originates from the double layer, while hydronium cations contribute with a mixture of both, double layer capacitance and pseudocapacitance.

  18. Leptospirosis and Pets

    Science.gov (United States)

    ... Bacterial Special Pathogens Branch (BSPB) BSPB Laboratory Submissions Pets Recommend on Facebook Tweet Share Compartir Leptospirosis is ... that can affect human and animals, including your pets. All animals can potentially become infected with Leptospirosis. ...

  19. Heart PET scan

    Science.gov (United States)

    ... nuclear medicine scan; Heart positron emission tomography; Myocardial PET scan ... A PET scan requires a small amount of radioactive material (tracer). This tracer is given through a vein (IV), ...

  20. SiPM-PET with a short optical fiber bundle for simultaneous PET-MR imaging.

    Science.gov (United States)

    Hong, Seong Jong; Kang, Han Gyoo; Ko, Guen Bae; Song, In Chan; Rhee, June-Tak; Lee, Jae Sung

    2012-06-21

    For positron emission tomography (PET) inserts to magnetic resonance imaging (MRI) applications, optical fibers have been used for some time to transfer scintillation photons to photomultiplier tubes positioned outside the fringe magnetic field. We previously proposed a novel utilization of an optical fiber for good radio frequency (RF) transmission from body coils to an imaging object. Optical fiber bundles between silicon photomultipliers (SiPM) and scintillation crystals provide an increased spacing between RF-shielded electronics boxes, facilitating RF passage from the body RF coils to imaging objects. In this paper, we present test results of a SiPM-PET system with a short optical fiber bundle for simultaneous PET-MR imaging. We built the SiPM-PET system which consisted of 12 SiPM-PET modules; each module was assembled with a lutetium yttrium oxyorthosilicatecrystal block, a 31 mm optical fiber bundle, a Hamamatsu multi-pixel photon counter S11064-050P and a signal processing box shielded with copper. The SiPM-PET system, with a face-to-face distance of 71 mm, was placed inside a 3 T MRI. A small surface coil placed inside the SiPM-PET system was used to receive the signal from phantoms while the body RF coil transmitted the RF pulses. The SiPM-PET system showed little performance degradation during the simultaneous PET-MR imaging and it caused no significant degradation of MR images with turbo spin echo (TSE), gradient echo or 3D spoiled gradient recalled sequences. Echo planar imaging MR images with and without the SiPM-PET inside the MR scanner were significantly worse than the images obtained with the TSE sequence.

  1. Characterization of a sub-assembly of 3D position sensitive cadmium zinc telluride detectors and electronics from a sub-millimeter resolution PET system

    Science.gov (United States)

    Abbaszadeh, Shiva; Gu, Yi; Reynolds, Paul D.; Levin, Craig S.

    2016-09-01

    Cadmium zinc telluride (CZT) offers key advantages for small animal positron emission tomography (PET), including high spatial and energy resolution and simple metal deposition for fabrication of very small pixel arrays. Previous studies have investigated the intrinsic spatial, energy, and timing resolution of an individual sub-millimeter resolution CZT detector. In this work we present the first characterization results of a system of these detectors. The 3D position sensitive dual-CZT detector module and readout electronics developed in our lab was scaled up to complete a significant portion of the final PET system. This sub-system was configured as two opposing detection panels containing a total of twelve 40~\\text{mm}× 40~\\text{mm}× 5 mm monolithic CZT crystals for proof of concept. System-level characterization studies, including optimizing the trigger threshold of each channel’s comparators, were performed. 68Ge and 137Cs radioactive isotopes were used to characterize the energy resolution of all 468 anode channels in the sub-system. The mean measured global 511 keV photopeak energy resolution over all anodes was found to be 7.35+/- 1.75 % FWHM after correction for photon interaction depth-dependent signal variation. The measured global time resolution was 37 ns FWHM, a parameter to be further optimized, and the intrinsic spatial resolution was 0.76 mm FWHM.

  2. Single-grain Si thin-film transistors for monolithic 3D-ICs and flexible electronics

    NARCIS (Netherlands)

    Ishihara, R.; Zhang, J.; Trifunovic, M.; Derakhshandeh Kheljani, J.; Golshani, N.; Tajari Mofrad, M.R.; Chen, T.; Beenakker, C.I.M.; Shimoda, T.

    2014-01-01

    We review our recent achievements in monolithic 3D-ICs and flexible electronics based on single-grain Si TFTs that are fabricated inside a single-grain with a low-temperature process. Based on pulsed-laser crystallization and submicron sized cavities made in the substrate, amorphous-Si precursor

  3. Automatic crystal lookup table generation for PET detector calibration by fusion of information from multiple approaches%基于多种探测算法结果分级融合的PET探测器晶体查找表建立算法

    Institute of Scientific and Technical Information of China (English)

    李丽平; 周鑫; 李强

    2016-01-01

    高分辨率是现代正电子发射型断层显像仪(Positron Emission Tomography,PET)设备最重要的技术指标之一,高分辨率PET探测器通常由海量闪烁晶体组成,这使得探测器校准时,晶体查找表建立的工作量大幅增加,从而对相关自动化算法的鲁棒性提出了更高的要求.目前,晶体阵列的矫正主要依赖固定放射源对探测器晶体阵列成像得到的光子二维位置直方图.高分辨率PET探测器的晶体阵列中晶体个数增多,尺寸变小,导致二维位置直方图信噪比下降,且非线性形变更加复杂,使已有的晶体查找表建立算法都无法得到理想的自动化效率.在测试了多种前沿的晶体查找表建立算法后发现,某些算法的结果之间有很强的互补性,可以通过将多种算法结果相融合的方法得到优于单一探测算法的结果.因此提出了一种基于多种探测算法结果分级融合的晶体查找表建立算法,在实现过程中选取了三种互补性较强的晶体探测方法,分级融合其结果,大幅度降低了二维位置直方图上晶体分割的出错概率,获得了鲁棒的结果.%Background: High resolution is of key importance for positron emission tomography (PET) devices. Modern PET scanners use a large number of crystals in detector blocks to improve their resolution. The extra crystals lead to a significant increase in workload of crystal identification in PET detector calibration. Hence the robustness of crystal identification algorithms becomes a challenge. Crystal identification is typically based on flood histograms obtained by irradiating the detector blocks with an annihilation photonflood source. More crystals of smaller size degrade the quality of flood histogram and generate more complex spatial distortions. Existing crystal identification methods are not robust enough to handle these cases.Purpose: Our study aims to improve the robustness and success rate of crystal identification on PET

  4. Development of a full-ring ;add-on PET; prototype: A head coil with DOI-PET detectors for integrated PET/MRI

    Science.gov (United States)

    Nishikido, F.; Fujiwara, M.; Tashima, H.; Akram, M. S. H.; Suga, M.; Obata, T.; Yamaya, T.

    2017-08-01

    We developed a full-ring ;add-on PET; prototype which is brain-dedicated and consists of a RF-head coil with four-layer depth-of-interaction (DOI) PET detectors for integrated PET/MRI in order to evaluate performance of our previously proposed add-on PET system and to investigate the mutual influences between the individual PET and MRI modalities when they are integrated in simultaneous measurements. In this add-on PET prototype, the DOI detectors are mounted on the head coil and close to the patient head. As a result, higher sensitivity and higher spatial resolution can be achieved for the integrated PET/MRI, compared with conventional whole body PET/MRI systems. In addition, implementation cost can be reduced, tuning of the RF-coil can be optimized and PET and MRI images can be obtained simultaneously in exactly the same positions. Specifically, the full-ring prototype consists of eight DOI-PET detectors and a birdcage type head coil of a 3T MRI. The radius of the PET ring is 123.9 mm. The distance from the center to the RF-coil elements is 130.5 mm. The scintillator blocks consist of lutetium-yttrium oxyorthosilicate scintillators arranged in 19×6×4 layers with reflectors inserted between them. The size of each crystal element is 2.0 mm×2.0 mm ×5.0 mm. We evaluated performance of the full-ring prototype in simultaneous measurements of the integrated PET/MRI. We obtained spatial resolutions of 2.3 mm at the center of the field-of-view (FOV) and lower than 3.5 mm in the whole FOV. The energy resolution of 19.4% was obtained for 511 keV gamma-rays. In addition, we observed no degradation of PET performance caused by the MRI measurement. The signal-to-noise ratio (SNR) of the MRI image was 209.4 in simultaneous measurements with the PET. The maximum ΔB0 and maximum difference of the secondary magnetic field due to the eddy current effect were smaller than 0.8 ppm and ±5.0 μT, respectively. We concluded that sufficient spatial resolution and detector

  5. Monolithically integrated Ge CMOS laser

    Science.gov (United States)

    Camacho-Aguilera, Rodolfo

    2014-02-01

    Ge-on-Si devices are explored for photonic integration. Through the development of better growth techniques, monolithic integration, laser design and prototypes, it was possible to probe Ge light emitters with emphasis on lasers. Preliminary worked shows thermal photonic behavior capable of enhancing lamination at high temperatures. Increase luminescence is observed up to 120°C from L-band contribution. Higher temperatures show contribution from Δ -band. The increase carrier thermal contribution suggests high temperature applications for Ge light emitters. A Ge electrically pumped laser was probed under 0.2% biaxial strain and doping concentration ~4.5×1019cm-3 n-type. Ge pnn lasers exhibit a gain >1000cm-1 with 8mW power output, presenting a spectrum range of over 200nm, making Ge the ideal candidate for Si photonics. Large temperatures fluctuations and process limit the present device. Theoretically a gain of >4000cm- gain is possible with a threshold of as low as 1kA/cm2. Improvements in Ge work

  6. PET/碳纳米管共混物的研究进展%Research progress in PET/carbon nanotube blend

    Institute of Scientific and Technical Information of China (English)

    武荣瑞

    2012-01-01

    综述了聚对苯二甲酸乙二醇酯(PET)/碳纳米管(CNTs)的共混物的制备和性能.官能化CNTs比未官能化CNTs在PET母体中的分散性得到改善;PET/未官能化CNTs共混物和PET/官能化CNTs共混物相比PET,熔融结晶温度均增高,具有更高的结晶度;PET/未官能化CNTs共混物的熔点变化不大,而PET/官能化CNTs共混物的熔点的变化取决于官能化CNTs 中引入官能团的化学结构;PET/未官能化CNTs共混物和PET/官能化CNTs共混物的熔体黏度均比PET有所提高,切力变稀行为比PET也有所增强:PET/未官能化CNTs共混物和PET/官能化CNTs其混物的热稳定性、导电性能及机械性能均得到改善.%The preparation and properties of polyethylene terephthalate (PET)/carbon nanotube(CNTs) blend were reviewed. The dispersion of functionalized CNTs in PET matrix was better than that of non-functionalized CNTs. As compared with PET, PET/non-functionalized CNTs and PET/functionalized CNTs had higher melt crystallization temperature and crystallinity when their thermal stability, conductivity and mechanical properties were improved, the melt viscosity was increased and the shear thinning behavior was enhanced. The melting point of PET/functionalized CNTs blend depended on the chemical structure of functional group in functionalized nanotube when the melting point of PET/non-functionalized CNTs did not change greatly.

  7. A nanofabricated, monolithic, path-separated electron interferometer

    CERN Document Server

    Agarwal, Akshay; Hobbs, Richard; van Dyck, Dirk; Berggren, Karl K

    2016-01-01

    We report a self-aligned, monolithic electron interferometer, consisting of two 45 nm thick silicon layers separated by 20 $\\mu$m. This interferometer was fabricated from a single crystal silicon cantilever on a transmission electron microscope grid by gallium focused ion-beam milling. Using this interferometer, we demonstrate beam path-separation, and obtain interference fringes in a Mach-Zehnder geometry, in an unmodified 200 kV transmission electron microscope. The fringes have a period of 0.32 nm, which corresponds to the $\\left[\\bar{1}\\bar{1}1\\right]$ lattice planes of silicon, and a maximum contrast of 15 %. This design can potentially be scaled to millimeter-scale, and used in electron holography. It can also be applied to perform fundamental physics experiments, such as interaction-free measurement with electrons.

  8. Initial results of simultaneous PET/MRI experiments with an MRI-compatible silicon photomultiplier PET scanner.

    Science.gov (United States)

    Yoon, Hyun Suk; Ko, Guen Bae; Kwon, Sun Il; Lee, Chan Mi; Ito, Mikiko; Chan Song, In; Lee, Dong Soo; Hong, Seong Jong; Lee, Jae Sung

    2012-04-01

    The most investigated semiconductor photosensor for MRI-compatible PET detectors is the avalanche photodiode (APD). However, the silicon photomultiplier (SiPM), also called the Geiger-mode APD, is gaining attention in the development of the next generation of PET/MRI systems because the SiPM has much better performance than the APD. We have developed an MRI-compatible PET system based on multichannel SiPM arrays to allow simultaneous PET/MRI. The SiPM PET scanner consists of 12 detector modules with a ring diameter of 13.6 cm and an axial extent of 3.2 cm. In each detector module, 4 multichannel SiPM arrays (with 4 × 4 channels arranged in a 2 × 2 array to yield 8 × 8 channels) were coupled with 20 × 18 Lu(1.9)Gd(0.1)SiO(5):Ce crystals (each crystal is 1.5 × 1.5 × 7 mm) and mounted on a charge division network for multiplexing 64 signals into 4 position signals. Each detector module was enclosed in a shielding box to reduce interference between the PET and MRI scanners, and the temperature inside the box was monitored for correction of the temperature-dependent gain variation of the SiPM. The PET detector signal was routed to the outside of the MRI room and processed with a field programmable gate array-based data acquisition system. MRI compatibility tests and simultaneous PET/MRI acquisitions were performed inside a 3-T clinical MRI system with 4-cm loop receiver coils that were built into the SiPM PET scanner. Interference between the imaging systems was investigated, and phantom and mouse experiments were performed. No radiofrequency interference on the PET signal or degradation in the energy spectrum and flood map was shown during simultaneous PET/MRI. The quality of the MRI scans acquired with and without the operating PET showed only slight degradation. The results of phantom and mouse experiments confirmed the feasibility of this system for simultaneous PET/MRI. Simultaneous PET/MRI was possible with a multichannel SiPM-based PET scanner, with no

  9. AX-PET: A novel PET concept with G-APD readout

    CERN Document Server

    Heller, M; Casella, C; Chesi, E; De Leo, R; Dissertori, G; Fanti, V; Gillam, J E; Joram, C; Lustermann, W; Nappi, E; Oliver, J F; Pauss, F; Rafecas, M; Rudge, A; Ruotsalainen, U; Schinzel, D; Schneider, T; Seguinot, J; Solevi, P; Stapnes, S; Tuna, U; Weilhammer, P

    2012-01-01

    The AX-PET collaboration has developed a novel concept for high resolution PET imaging to overcome some of the performance limitations of classical PET cameras, in particular the compromise between spatial resolution and sensitivity introduced by the parallax error. The detector consists of an arrangement of long LYSO scintillating crystals axially oriented around the field of view together with arrays of wave length shifter strips orthogonal to the crystals. This matrix allows a precise 3D measurement of the photon interaction point. This is valid both for photoelectric absorption at 511 key and for Compton scattering down to deposited energies of about 100 keV. Crystals and WLS strips are individually read out using Geiger-mode Avalanche Photo Diodes (G-APDs). The sensitivity of such a detector can be adjusted by changing the number of layers and the resolution is defined by the crystal and strip dimensions. Two AX-PET modules were built and fully characterized in dedicated test set-ups at CERN, with point-...

  10. Study on the Synthesis and Properties of PET Using Hydrotalcite as Catalyst

    Institute of Scientific and Technical Information of China (English)

    Li Guihe; Fu Zhifeng; Cao Ding

    2013-01-01

    Poly(ethylene terephthalate) (PET) was synthesized by the in-situ polymerization method using layered double hydrotalcite (LDH) as the catalyst, and the thermal and lfame retardation properties of PET were investigated as required. As identiifed by differential scanning calorimetry (DSC) and thermogravimetric (TGA) analysis, the crystallization rate and thermal degradation temperature of the as-prepared PET sample were enhanced compared with commercial PET sample. It was conifrmed from the ifre-resistant property study that the LDH can be used as an efifcient lfame-retardant besides func-tioning as a catalyst in the transesteriifcation/polycondensation process for PET synthesis.

  11. Modified monolithic silica capillary for preconcentration of catecholamines

    Institute of Scientific and Technical Information of China (English)

    Wei Chang; Tusyo-shi Komazu

    2009-01-01

    Preconcentration of catecholamines by the modified monolithic silica in the capillary was investigated in this study. In order to achieve a microchip-based method for determining catecholamines in the saliva, the monolithic silica was fabricated in the capillary and the monolithic silica was chemically modified by on-column reaction with phenylboronate. Different modified methods were compared. The concentration conditions were optimized. This study indicates the applicability of the modified monolithic silica capillary when it was used to concentrate catecholamines.

  12. Modified monolithic silica capillary for preconcentration of catecholamines

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Preconcentration of catecholamines by the modified monolithic silica in the capillary was investigated in this study. In order to achieve a microchip-based method for determining catecholamines in the saliva,the monolithic silica was fabricated in the capillary and the monolithic silica was chemically modified by on-column reaction with phenylboronate. Different modified methods were compared. The concentration conditions were optimized. This study indicates the applicability of the modified monolithic sili...

  13. Fracture resistance of monolithic zirconia molar crowns with reduced thickness

    OpenAIRE

    Nakamura, Keisuke; Harada, A.; Inagaki, R.; Kanno, Taro; Niwano, Y; Milleding, Percy; Ørtengren, Ulf Thore

    2015-01-01

    This is the accepted manuscript version. Published version is available at Acta Odontologica Scandinavica Objectives. The purpose of the present study was to analyze the relationship between fracture load of monolithic zirconia crowns and axial/occlusal thickness, and to evaluate the fracture resistance of monolithic zirconia crowns with reduced thickness in comparison with that of monolithic lithium disilicate crowns with regular thickness. Materials and methods. Monolithic zi...

  14. Development of a monolithic ferrite memory array

    Science.gov (United States)

    Heckler, C. H., Jr.; Bhiwandker, N. C.

    1972-01-01

    The results of the development and testing of ferrite monolithic memory arrays are presented. This development required the synthesis of ferrite materials having special magnetic and physical characteristics and the development of special processes; (1) for making flexible sheets (laminae) of the ferrite composition, (2) for embedding conductors in ferrite, and (3) bonding ferrite laminae together to form a monolithic structure. Major problems encountered in each of these areas and their solutions are discussed. Twenty-two full-size arrays were fabricated and fired during the development of these processes. The majority of these arrays were tested for their memory characteristics as well as for their physical characteristics and the results are presented. The arrays produced during this program meet the essential goals and demonstrate the feasibility of fabricating monolithic ferrite memory arrays by the processes developed.

  15. Carbon Fiber Composite Monoliths as Catalyst Supports

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I [ORNL; Gallego, Nidia C [ORNL; Pickel, Joseph M [ORNL; Blom, Douglas Allen [ORNL; Burchell, Timothy D [ORNL

    2006-01-01

    Carbon fiber composite monoliths are rigid bodies that can be activated to a large surface area, have tunable porosity, and proven performance in gas separation and storage. They are ideal as catalyst supports in applications where a rigid support, with open structure and easy fluid access is desired. We developed a procedure for depositing a dispersed nanoparticulate phase of molybdenum carbide (Mo2C) on carbon composite monoliths in the concentration range of 3 to 15 wt% Mo. The composition and morphology of this phase was characterized using X-ray diffraction and electron microscopy, and a mechanism was suggested for its formation. Molybdenum carbide is known for its catalytic properties that resemble those of platinum group metals, but at a lower cost. The materials obtained are expected to demonstrate catalytic activity in a series of hydrocarbon reactions involving hydrogen transfer. This project demonstrates the potential of carbon fiber composite monoliths as catalyst supports.

  16. Carbon Fiber Composite Monoliths for Catalyst Supports

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I [ORNL; Gallego, Nidia C [ORNL; Pickel, Joseph M [ORNL; Blom, Douglas Allen [ORNL; Burchell, Timothy D [ORNL

    2006-01-01

    Carbon fiber composite monoliths are rigid bodies that can be activated to a large surface area, have tunable porosity, and proven performance in gas separation and storage. They are ideal as catalyst supports in applications where a rigid support, with open structure and easy fluid access is desired. We developed a procedure for depositing a dispersed nanoparticulate phase of molybdenum carbide (Mo2C) on carbon composite monoliths in the concentration range of 3 to 15 wt% Mo. The composition and morphology of this phase was characterized using X-ray diffraction and electron microscopy, and a mechanism was suggested for its formation. Molybdenum carbide is known for its catalytic properties that resemble those of platinum group metals, but at a lower cost. The materials obtained are expected to demonstrate catalytic activity in a series of hydrocarbon reactions involving hydrogen transfer. This project demonstrates the potential of carbon fiber composite monoliths as catalyst supports.

  17. Eigenpolarization theory of monolithic nonplanar ring oscillators

    Science.gov (United States)

    Nilsson, Alan C.; Gustafson, Eric K.; Byer, Robert L.

    1989-01-01

    Diode-laser-pumped monolithic nonplanar ring oscillators (NPROs) in an applied magnetic field can operate as unidirectional traveling-wave lasers. The diode laser pumping, monolithic construction, and unidirectional oscillation lead to narrow linewidth radiation. Here, a comprehensive theory of the eigenpolarizations of a monolithic NPRO is presented. It is shown how the properties of the integral optical diode that forces unidirectional operation depend on the choice of the gain medium, the applied magnetic field, the output coupler, and the geometry of the nonplanar ring light path. Using optical equivalence theorems to gain insight into the polarization characteristics of the NPRO, a strategy for designing NPROs with low thresholds and large loss nonreciprocities is given. An analysis of the eigenpolarizations for one such NPRO is presented, alternative optimization approaches are considered, and the prospects for further reducing the linewidths of these lasers are briefly discussed.

  18. Physical and chemical sensing using monolithic semiconductor optical transducers

    Science.gov (United States)

    Zappe, Hans P.; Hofstetter, Daniel; Maisenhoelder, Bernd; Moser, Michael; Riel, Peter; Kunz, Rino E.

    1997-09-01

    We present two monolithically integrated optical sensor systems based on semiconductor photonic integrated circuits. These compact, robust and highly functional transducers perform all necessary optical and electro-optical functions on-chip; extension to multi-sensor arrays is easily envisaged. A monolithic Michelson interferometer for high-resolution displacement measurement and a monolithic Mach-Zehnder interferometer for refractometry are discussed.

  19. Aperture scaling effects with monolithic periodically poled lithium niobate optical parametric oscillators and generators.

    Science.gov (United States)

    Missey, M; Dominic, V; Powers, P; Schepler, K L

    2000-02-15

    We used elliptical beams to demonstrate aperture scaling effects in nanosecond single-grating and multigrating periodically poled lithium niobate (PPLN) monolithic optical parametric oscillators and generators. Increasing the cavity Fresnel number in single-grating crystals broadened both the beam divergence and the spectral bandwidth. Both effects are explained in terms of the phase-matching geometry. These effects are suppressed when a multigrating PPLN crystal is used because the individual gratings provide small effective subapertures. A flood-pumped multigrating optical parametric generator displayed a low output beam divergence and contained 19 pairs of signal and idler frequencies.

  20. Detector block based on arrays of 144 SiPMs and monolithic scintillators: A performance study

    Energy Technology Data Exchange (ETDEWEB)

    González, A.J.; Conde, P.; Iborra, A. [Institute for Instrumentation in Molecular Imaging (I3M), Universidad Politécnica de Valencia – CSIC – CIEMAT (Spain); Aguilar, A. [Communications and Digital Systems Design Group (DSDC), Universidad de Valencia (Spain); Bellido, P. [Institute for Instrumentation in Molecular Imaging (I3M), Universidad Politécnica de Valencia – CSIC – CIEMAT (Spain); García-Olcina, R. [Communications and Digital Systems Design Group (DSDC), Universidad de Valencia (Spain); Hernández, L.; Moliner, L.; Rigla, J.P.; Rodríguez-Álvarez, M.J.; Sánchez, F.; Seimetz, M.; Soriano, A. [Institute for Instrumentation in Molecular Imaging (I3M), Universidad Politécnica de Valencia – CSIC – CIEMAT (Spain); Torres, J. [Communications and Digital Systems Design Group (DSDC), Universidad de Valencia (Spain); Vidal, L.F.; Benlloch, J.M. [Institute for Instrumentation in Molecular Imaging (I3M), Universidad Politécnica de Valencia – CSIC – CIEMAT (Spain)

    2015-07-01

    We have developed a detector block composed by a monolithic LYSO scintillator coupled to a custom made 12×12 SiPMs array. The design is mainly focused to applications such as Positron Emission Tomography. The readout electronics is based on 3 identical and scalable Application Specific Integrated Circuits (ASIC). We have determined the main performance of the detector block namely spatial, energy, and time resolution but also the system capability to determine the photon depth of interaction, for different crystal surface treatments. Intrinsic detector spatial resolution values as good as 1.7 mm FWHM and energies of 15% for black painted crystals were measured.

  1. Increased thermal conductivity monolithic zeolite structures

    Science.gov (United States)

    Klett, James; Klett, Lynn; Kaufman, Jonathan

    2008-11-25

    A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

  2. Characterization of CIM monoliths as enzyme reactors.

    Science.gov (United States)

    Vodopivec, Martina; Podgornik, Ales; Berovic, Marin; Strancar, Ales

    2003-09-25

    The immobilization of the enzymes citrate lyase, malate dehydrogenase, isocitrate dehydrogenase and lactate dehydrogenase to CIM monolithic supports was performed. The long-term stability, reproducibility, and linear response range of the immobilized enzyme reactors were investigated along with the determination of the kinetic behavior of the enzymes immobilized on the CIM monoliths. The Michaelis-Menten constant K(m) and the turnover number k(3) of the immobilized enzymes were found to be flow-unaffected. Furthermore, the K(m) values of the soluble and immobilized enzyme were found to be comparable. Both facts indicate the absence of a diffusional limitation in immobilized CIM enzyme reactors.

  3. Monolithically integrated optoelectronic down-converter (MIOD)

    Science.gov (United States)

    Portnoi, Efrim L.; Venus, G. B.; Khazan, A. A.; Gorfinkel, Vera B.; Kompa, Guenter; Avrutin, Evgenii A.; Thayne, Iain G.; Barrow, David A.; Marsh, John H.

    1995-06-01

    Optoelectronic down-conversion of very high-frequency amplitude-modulated signals using a semiconductor laser simultaneously as a local oscillator and a mixer is proposed. Three possible constructions of a monolithically integrated down-converter are considered theoretically: a four-terminal semiconductor laser with dual pumping current/modal gain control, and both a passively mode-locked and a passively Q-switched semiconductor laser monolithically integrated with an electroabsorption or pumping current modulator. Experimental verification of the feasibility of the concept of down conversion in a laser diode is presented.

  4. Structural features and relaxation properties of PET/PC blends containing impact strength modifier and chain extender

    Directory of Open Access Journals (Sweden)

    2009-10-01

    Full Text Available It has been investigated how methylene diphenyl diisocyanate (MDI influences the morphology, rheological, mechanical and relaxation properties, as well as PET crystallizability, of PET/PC/(PP/EPDM ternary blends produced by the reactive extrusion process. It appears that irrespective of phase structure of the blends, MDI causes a rise in melt viscosity (decreased MFI-values of the material which is the result of an increased molecular weight of the macromolecules; PET crystallization becomes retarded. MDI improves compatibility between PET and PC in PET/PC/(PP/EPDM ternary blends. Addition of MDI leads to higher values of the dynamic shear modulus for PET high elastic state (in the temperature range between Tg PET and cool crystallization temperature of PET; the PET cool crystallization and melt crystallization processes become retarded; the PET and PC glass transition temperatures approach one another. MDI has been shown not to influence significantly the blend morphology or the character of interaction between the PP/EPDM disperse phase and PET/PC blend matrix.

  5. Solvothermal removal of the organic template from L{sub 3} ('sponge') templated silica monoliths

    Energy Technology Data Exchange (ETDEWEB)

    Dabbs, Daniel M. [Princeton University, Department of Chemical Engineering (United States); Mulders, Norbert [University of Delaware, Department of Physics and Astronomy (United States); Aksay, Ilhan A. [Princeton University, Department of Chemical Engineering (United States)], E-mail: iaksay@princeton.EDU

    2006-10-15

    We compare the methods of continuous solvent (Soxhlet) and supercritical solvent extractions for the removal of the organic template from nanostructured silica monoliths. Our monoliths are formed by templating the L{sub 3} liquid crystal phase of cetylpyridinium chloride in aqueous solutions with tetramethoxy silane. The monoliths that result from both Soxhlet and supercritical extraction methods are mechanically robust, optically clear, and free of cracks. The Soxhlet method compares favorably with supercritical solvent extraction in that equivalent L{sub 3}-templated silica can be synthesized without the use of specialized reactor hardware or higher temperatures and high pressures, while avoiding noxious byproducts. The comparative effectiveness of various solvents in the Soxhlet process is related to the Hildebrand solubility parameter, determined by the effective surface area of the extracted silica.

  6. Disaster Preparedness for Your Pet

    Science.gov (United States)

    ... and prepare a disaster kit for your pet. Leaving pets out of evacuation plans can put pets, ... during an evacuation Contact your local emergency management office and ask if they offer accommodations for owners ...

  7. Sensory analysis of pet foods.

    Science.gov (United States)

    Koppel, Kadri

    2014-08-01

    Pet food palatability depends first and foremost on the pet and is related to the pet food sensory properties such as aroma, texture and flavor. Sensory analysis of pet foods may be conducted by humans via descriptive or hedonic analysis, pets via acceptance or preference tests, and through a number of instrumental analysis methods. Sensory analysis of pet foods provides additional information on reasons behind palatable and unpalatable foods as pets lack linguistic capabilities. Furthermore, sensory analysis may be combined with other types of information such as personality and environment factors to increase understanding of acceptable pet foods. Most pet food flavor research is proprietary and, thus, there are a limited number of publications available. Funding opportunities for pet food studies would increase research and publications and this would help raise public awareness of pet food related issues. This mini-review addresses current pet food sensory analysis literature and discusses future challenges and possibilities.

  8. PET studies in epilepsy

    OpenAIRE

    Sarikaya, Ismet

    2015-01-01

    Various PET studies, such as measurements of glucose, serotonin and oxygen metabolism, cerebral blood flow and receptor bindings are availabe for epilepsy. 18Fluoro-2-deoxyglucose (18F-FDG) PET imaging of brain glucose metabolism is a well established and widely available technique. Studies have demonstrated that the sensitivity of interictal FDG-PET is higher than interictal SPECT and similar to ictal SPECT for the lateralization and localization of epileptogenic foci in presurgical patients...

  9. Clinical PET application

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sang Moo; Hong, Song W.; Choi, Chang W.; Yang, Seong Dae [Korea Cancer Center Hospital, Seoul (Korea)

    1997-12-01

    PET gives various methabolic images, and is very important, new diagnostic modality in clinical oncology. In Korea Cancer Center Hospital, PET is installed as a research tool of long-mid-term atomic research project. For the efficient use of PET for clinical and research projects, income from the patients should be managed to get the raw material, equipment, manpower, and also for the clinical PET research. 1. Support the clinical application of PET in oncology. 2. Budgetary management of income, costs for raw material, equipment, manpower, and the clinical PET research project. In this year, 250 cases of PET images were obtained, which resulted total income of 180,000,000 won. 50,000,000 won was deposited for the 1998 PET clinical research. Second year PET clinical research should be managed under unified project. Increased demand for {sup 18}FDG in and outside KCCH need more than 2 times production of {sup 18}FDG in a day purchase of HPLC pump and {sup 68}Ga pin source which was delayed due to economic crisis, should be done early in 1998. (author). 2 figs., 3 tabs.

  10. Monolithic Integration of GaN-based LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Jin-Ping, E-mail: jpao@ee.tokushima-u.ac.jp [Institute of Technology and Science, University of Tokushima 2-1 Minami-Josanjima, Tokushima 770-8506 (Japan)

    2011-02-01

    The technology of monolithically integrated GaN-based light-emitting diodes (LEDs) is reported. First, the technology details to realize monolithic integration are described, including the circuit design for high-voltage and alternating current (AC) operation and the technologies for device isolation. The performances of the fabricated monolithic LED arrays are then demonstrated. A monolithic series array with totally 40 LEDs exhibited expected operation function under AC bias. The operation voltage of the array is 72 V when 20 LEDs were connected in series. Some modified circuit designs for high-voltage operation and other monolithic LED arrays are finally reviewed.

  11. Monolithic resonant optical reflector laser diodes

    Science.gov (United States)

    Hirata, T.; Suehiro, M.; Maeda, M.; Hihara, M.; Hosomatsu, H.

    1991-10-01

    The first monolithic resonant optical reflector laser diode that has a waveguide directional coupler and two DBR reflectors integrated by compositional disordering of quantum-well heterostructures is described. A linewidth of 440 kHz was obtained, and this value is expected to be greatly decreased by reducing the propagation loss in the integrated waveguide.

  12. Constant capacitance in nanopores of carbon monoliths.

    Science.gov (United States)

    García-Gómez, Alejandra; Moreno-Fernández, Gelines; Lobato, Belén; Centeno, Teresa A

    2015-06-28

    The results obtained for binder-free electrodes made of carbon monoliths with narrow micropore size distributions confirm that the specific capacitance in the electrolyte (C2H5)4NBF4/acetonitrile does not depend significantly on the micropore size and support the foregoing constant result of 0.094 ± 0.011 F m(-2).

  13. Development and evaluation of an ultra-fast ASIC for future PET scanners using TOF-capable MPPC array detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ambe, T., E-mail: hiro-a-be.n@akane.waseda.jp [Research Institute for Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo (Japan); Ikeda, H. [ISAS/JAXA, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara-shi, Kanagawa (Japan); Kataoka, J.; Matsuda, H.; Kato, T. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo (Japan)

    2015-01-21

    We developed a front-end ASIC for future PET scanners with Time-Of-Flight (TOF) capability to be coupled with 4×4 Multi-Pixel Photon Counter (MPPC) arrays. The ASIC is designed based on the open-IP project proposed by JAXA and realized in TSMC 0.35 μm CMOS technology. The circuit comprises 16-channel, low impedance current conveyors for effectively acquiring fast MPPC signals. For precise measurement of the coincidence timing of 511-keV gamma rays, the leading-edge method was used to discriminate the signals. We first tested the time response of the ASIC by illuminating each channel of a MPPC array device 3×3 mm{sup 2} in size with a Pico-second Light Pulsar with a light emission peak of 655 nm and pulse duration of 54 ps (FWHM). We obtained 105 ps (FWHM) on average for each channel in time jitter measurements. Moreover, we compensated for the time lag of each channel with inner delay circuits and succeeded in suppressing about a 700-ps lag to only 15 ps. This paper reports TOF measurements using back-to-back 511-keV signals, and suggests that the ASIC can be a promising device for future TOF-PET scanners based on the MPPC array. - Highlights: • We developed a newly designed large-area monolithic MPPC array. • We obtained fine gain uniformity, and good energy and time resolutions when coupled to the LYSO scintillator. • We fabricated gamma-ray camera consisting of the MPPC array and the submillimeter pixelized LYSO and GGAG scintillators. • In the flood images, each crystal of scintillator matrices was clearly resolved. • Good energy resolutions for 662 keV gamma-rays for each LYSO and GGAG scintillator matrices were obtained.

  14. Effect of absorbed pump power on the quality of output beam from monolithic microchip lasers

    Indian Academy of Sciences (India)

    Pranab K Mukhopadhyay; K Ranganathan; Jogy George; S K Sharma; T P S Nathan

    2002-04-01

    The dependence of the beam propagation factor (2 parameter) with the absorbed pump power in the case of monolithic microchip laser under face-cooled configuration is extensively studied. Our investigations show that the 2 parameter is related to the absorbed pump power through two parameters ( and ) whose values depend on the laser material properties and laser configuration. We have shown that one parameter arises due to the oscillation of higher order modes in the microchip cavity and the other parameter accounts for the spherical aberration associated with the thermal lens induced by the pump beam. Such dependency of 2 parameter with the absorbed pump power is experimentally verified for a face-cooled monolithic microchip laser based on Nd3+ - doped GdVO4 crystal and the values of and parameters were estimated from the experimentally measured data points.

  15. Study on the Process Technology of PA6/PET Bicomponent Fiber

    Institute of Scientific and Technical Information of China (English)

    林耀

    2001-01-01

    PA6/PET bicomponent fiber at different spinning speedswere produced. Influences of cross blowing, spinning speed, PA6 and PET component ratio, drawing condition etc. on the mechanical properties, heat shrinkage,orientation and crystallization of the fiber were investigated. Also the rules among these influencing parameters were obtained. The splitting property of the fiber and its influence on the textile processing are discussed, which offers a base for the production of PA6/PET bicomponent fiber using splitting technology.

  16. AX-PET: A novel PET concept with G-APD readout

    Science.gov (United States)

    Bolle, E.; Casella, C.; Chesi, E.; De Leo, R.; Dissertori, G.; Fanti, V.; Gillam, J. E.; Heller, M.; Joram, C.; Lustermann, W.; Nappi, E.; Oliver, J. F.; Pauss, F.; Rafecas, M.; Rudge, A.; Ruotsalainen, U.; Schinzel, D.; Schneider, T.; Séguinot, J.; Solevi, P.; Stapnes, S.; Tuna, U.; Weilhammer, P.

    2012-12-01

    The AX-PET collaboration has developed a novel concept for high resolution PET imaging to overcome some of the performance limitations of classical PET cameras, in particular the compromise between spatial resolution and sensitivity introduced by the parallax error. The detector consists of an arrangement of long LYSO scintillating crystals axially oriented around the field of view together with arrays of wave length shifter strips orthogonal to the crystals. This matrix allows a precise 3D measurement of the photon interaction point. This is valid both for photoelectric absorption at 511 keV and for Compton scattering down to deposited energies of about 100 keV. Crystals and WLS strips are individually read out using Geiger-mode Avalanche Photo Diodes (G-APDs). The sensitivity of such a detector can be adjusted by changing the number of layers and the resolution is defined by the crystal and strip dimensions. Two AX-PET modules were built and fully characterized in dedicated test set-ups at CERN, with point-like 22Na sources. Their performance in terms of energy (Renergy≈11.8% (FWMH) at 511 keV) and spatial resolution was assessed (σaxial≈0.65 mm), both individually and for the two modules in coincidence. Test campaigns at ETH Zurich and at the company AAA allowed the tomographic reconstructions of more complex phantoms validating the 3D reconstruction algorithms. The concept of the AX-PET modules will be presented together with some characterization results. We describe a count rate model which allows to optimize the planing of the tomographic scans.

  17. AX-PET: A novel PET concept with G-APD readout

    Energy Technology Data Exchange (ETDEWEB)

    Bolle, E. [University of Oslo, NO-0317 Oslo (Norway); Casella, C. [Institute for Particle Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Chesi, E. [Ohio State University, Columbus, Ohio 43210 (United States); De Leo, R. [INFN, Sezione di Bari, I-70122 Bari (Italy); Dissertori, G. [Institute for Particle Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Fanti, V. [Universita e Sezione INFN di Cagliari (Italy); Gillam, J.E. [IFIC (Universidad de Valencia/CSIC), E-46071 Valencia (Spain); Heller, M., E-mail: Matthieu.Heller@cern.ch [CERN, PH Department, CH-1211 Geneva (Switzerland); Joram, C. [CERN, PH Department, CH-1211 Geneva (Switzerland); Lustermann, W. [Institute for Particle Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Nappi, E. [INFN, Sezione di Bari, I-70122 Bari (Italy); Oliver, J.F. [IFIC (Universidad de Valencia/CSIC), E-46071 Valencia (Spain); Pauss, F. [Institute for Particle Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Rafecas, M. [IFIC (Universidad de Valencia/CSIC), E-46071 Valencia (Spain); Rudge, A. [Ohio State University, Columbus, Ohio 43210 (United States); Ruotsalainen, U. [University of Michigan, Ann Arbor, MI 48109 (United States); University of Rome ' La Sapienza' , I-00185 Rome (Italy); Tampere University of Technology, FI-33100 Tampere (Finland); Schinzel, D. [Institute for Particle Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Schneider, T.; Seguinot, J. [CERN, PH Department, CH-1211 Geneva (Switzerland); Solevi, P. [IFIC (Universidad de Valencia/CSIC), E-46071 Valencia (Spain); and others

    2012-12-11

    The AX-PET collaboration has developed a novel concept for high resolution PET imaging to overcome some of the performance limitations of classical PET cameras, in particular the compromise between spatial resolution and sensitivity introduced by the parallax error. The detector consists of an arrangement of long LYSO scintillating crystals axially oriented around the field of view together with arrays of wave length shifter strips orthogonal to the crystals. This matrix allows a precise 3D measurement of the photon interaction point. This is valid both for photoelectric absorption at 511 keV and for Compton scattering down to deposited energies of about 100 keV. Crystals and WLS strips are individually read out using Geiger-mode Avalanche Photo Diodes (G-APDs). The sensitivity of such a detector can be adjusted by changing the number of layers and the resolution is defined by the crystal and strip dimensions. Two AX-PET modules were built and fully characterized in dedicated test set-ups at CERN, with point-like {sup 22}Na sources. Their performance in terms of energy (R{sub energy} Almost-Equal-To 11.8% (FWMH) at 511 keV) and spatial resolution was assessed ({sigma}{sub axial} Almost-Equal-To 0.65mm), both individually and for the two modules in coincidence. Test campaigns at ETH Zurich and at the company AAA allowed the tomographic reconstructions of more complex phantoms validating the 3D reconstruction algorithms. The concept of the AX-PET modules will be presented together with some characterization results. We describe a count rate model which allows to optimize the planing of the tomographic scans.

  18. My Pet Rock

    Science.gov (United States)

    Lark, Adam; Kramp, Robyne; Nurnberger-Haag, Julie

    2008-01-01

    Many teachers and students have experienced the classic pet rock experiment in conjunction with a geology unit. A teacher has students bring in a "pet" rock found outside of school, and the students run geologic tests on the rock. The tests include determining relative hardness using Mohs scale, checking for magnetization, and assessing luster.…

  19. My Pet Rock

    Science.gov (United States)

    Lark, Adam; Kramp, Robyne; Nurnberger-Haag, Julie

    2008-01-01

    Many teachers and students have experienced the classic pet rock experiment in conjunction with a geology unit. A teacher has students bring in a "pet" rock found outside of school, and the students run geologic tests on the rock. The tests include determining relative hardness using Mohs scale, checking for magnetization, and assessing luster.…

  20. Mobile PET Center Project

    Science.gov (United States)

    Ryzhikova, O.; Naumov, N.; Sergienko, V.; Kostylev, V.

    2017-01-01

    Positron emission tomography is the most promising technology to monitor cancer and heart disease treatment. Stationary PET center requires substantial financial resources and time for construction and equipping. The developed mobile solution will allow introducing PET technology quickly without major investments.

  1. Usage of Recycled Pet

    Directory of Open Access Journals (Sweden)

    A. Ebru Tayyar

    2010-01-01

    Full Text Available The increasing industrialization, urbanization and the technological development have caused to increase depletion of the natural resources and environmental pollution's problem. Especially, for the countries which have not enough space recycling of the waste eliminating waste on regular basis or decreasing the amount and volume of waste have provided the important advantages. There are lots of studies and projects to develop both protect resources and prevent environmental pollution. PET bottles are commonly used in beverage industry and can be reused after physical and chemical recycling processes. Usage areas of recycled PET have been developed rapidly. Although recycled PET is used in plastic industry, composite industry also provides usage alternatives of recycled PET. Textile is a suitable sector for recycling of some plastics made of polymers too. In this study, the recycling technologies and applications of waste PET bottles have been investigated and scientific works in this area have been summarized.

  2. The MINDView brain PET detector, feasibility study based on SiPM arrays

    Science.gov (United States)

    González, Antonio J.; Majewski, Stan; Sánchez, Filomeno; Aussenhofer, Sebastian; Aguilar, Albert; Conde, Pablo; Hernández, Liczandro; Vidal, Luis F.; Pani, Roberto; Bettiol, Marco; Fabbri, Andrea; Bert, Julien; Visvikis, Dimitris; Jackson, Carl; Murphy, John; O'Neill, Kevin; Benlloch, Jose M.

    2016-05-01

    The Multimodal Imaging of Neurological Disorders (MINDView) project aims to develop a dedicated brain Positron Emission Tomography (PET) scanner with sufficient resolution and sensitivity to visualize neurotransmitter pathways and their disruptions in mental disorders for diagnosis and follow-up treatment. The PET system should be compact and fully compatible with a Magnetic Resonance Imaging (MRI) device in order to allow its operation as a PET brain insert in a hybrid imaging setup with most MRI scanners. The proposed design will enable the currently-installed MRI base to be easily upgraded to PET/MRI systems. The current design for the PET insert consists of a 3-ring configuration with 20 modules per ring and an axial field of view of ~15 cm and a geometrical aperture of ~33 cm in diameter. When coupled to the new head Radio Frequency (RF) coil, the inner usable diameter of the complete PET-RF coil insert is reduced to 26 cm. Two scintillator configurations have been tested, namely a 3-layer staggered array of LYSO with 1.5 mm pixel size, with 35×35 elements (6 mm thickness each) and a black-painted monolithic LYSO block also covering about 50×50 mm2 active area with 20 mm thickness. Laboratory test results associated with the current MINDView PET module concept are presented in terms of key parameters' optimization, such as spatial and energy resolution, sensitivity and Depth of Interaction (DOI) capability. It was possible to resolve all pixel elements from the three scintillator layers with energy resolutions as good as 10%. The monolithic scintillator showed average detector resolutions varying from 3.5 mm in the entrance layer to better than 1.5 mm near the photosensor, with average energy resolutions of about 17%.

  3. The MINDView brain PET detector, feasibility study based on SiPM arrays

    Energy Technology Data Exchange (ETDEWEB)

    González, Antonio J., E-mail: agonzalez@i3m.upv.es [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain); Majewski, Stan [Radiology Research, Department of Radiology, University of Virginia, VA 22903 (United States); Sánchez, Filomeno [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain); Aussenhofer, Sebastian [NORAS MRI products GmbH, Hochberg (Germany); Aguilar, Albert; Conde, Pablo; Hernández, Liczandro; Vidal, Luis F. [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain); Pani, Roberto; Bettiol, Marco; Fabbri, Andrea [Department of Molecular Medicine, Sapienza University of Rome (Italy); Bert, Julien; Visvikis, Dimitris [Université de Bretagne Occidentale, Brest (France); Jackson, Carl; Murphy, John; O’Neill, Kevin [SensL Technologies, Cork (Ireland); Benlloch, Jose M. [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain)

    2016-05-11

    The Multimodal Imaging of Neurological Disorders (MINDView) project aims to develop a dedicated brain Positron Emission Tomography (PET) scanner with sufficient resolution and sensitivity to visualize neurotransmitter pathways and their disruptions in mental disorders for diagnosis and follow-up treatment. The PET system should be compact and fully compatible with a Magnetic Resonance Imaging (MRI) device in order to allow its operation as a PET brain insert in a hybrid imaging setup with most MRI scanners. The proposed design will enable the currently-installed MRI base to be easily upgraded to PET/MRI systems. The current design for the PET insert consists of a 3-ring configuration with 20 modules per ring and an axial field of view of ~15 cm and a geometrical aperture of ~33 cm in diameter. When coupled to the new head Radio Frequency (RF) coil, the inner usable diameter of the complete PET-RF coil insert is reduced to 26 cm. Two scintillator configurations have been tested, namely a 3-layer staggered array of LYSO with 1.5 mm pixel size, with 35×35 elements (6 mm thickness each) and a black-painted monolithic LYSO block also covering about 50×50 mm{sup 2} active area with 20 mm thickness. Laboratory test results associated with the current MINDView PET module concept are presented in terms of key parameters' optimization, such as spatial and energy resolution, sensitivity and Depth of Interaction (DOI) capability. It was possible to resolve all pixel elements from the three scintillator layers with energy resolutions as good as 10%. The monolithic scintillator showed average detector resolutions varying from 3.5 mm in the entrance layer to better than 1.5 mm near the photosensor, with average energy resolutions of about 17%.

  4. Development of brain PET using GAPD arrays.

    Science.gov (United States)

    Jung, Jin Ho; Choi, Yong; Hong, Key Jo; Kang, Jihoon; Hu, Wei; Lim, Hyun Keong; Huh, Yoonsuk; Kim, Sangsu; Jung, Jiwoong; Kim, Kyu Bom

    2012-03-01

    In recent times, there has been great interest in the use of Geiger-mode avalanche photodiodes (GAPDs) as scintillator readout in positron emission tomography (PET) detectors because of their advantages, such as high gain, compact size, low power consumption, and magnetic field insensitivity. The purpose of this study was to develop a novel PET system based on GAPD arrays for brain imaging. The PET consisted of 72 detector modules arranged in a ring of 330 mm diameter. Each PET module was composed of a 4 × 4 matrix of 3 × 3 × 20 mm(3) cerium-doped lutetium yttrium orthosilicate (LYSO) crystals coupled with a 4 × 4 array three-side tileable GAPD. The signals from each PET module were fed into preamplifiers using a 3 m long flat cable and then sent to a position decoder circuit (PDC), which output a digital address and an analog pulse of the interacted channel among 64 preamplifier signals transmitted from four PET detector modules. The PDC outputs were fed into field programmable gate array (FPGA)-embedded data acquisition (DAQ) boards. The analog signal was then digitized, and arrival time and energy of the signal were calculated and stored. The energy and coincidence timing resolutions measured for 511 keV gamma rays were 18.4 ± 3.1% and 2.6 ns, respectively. The transaxial spatial resolution and sensitivity in the center of field of view (FOV) were 3.1 mm and 0.32% cps/Bq, respectively. The rods down to a diameter of 2.5 mm were resolved in a hot-rod phantom image, and activity distribution patterns between the white and gray matters in the Hoffman brain phantom were well imaged. Experimental results indicate that a PET system can be developed using GAPD arrays and the GAPD-based PET system can provide high-quality PET imaging.

  5. Necking Point in PET High-speed Fiber Spinning

    Institute of Scientific and Technical Information of China (English)

    王夏琴; 唐志廉

    2001-01-01

    Cross-over method is established to predict necking point for PET high- speed fiber spinning. Even slowly crystallizing polymers such as PET can crystallize on the spinline at sufficiently high spinning speed. The development of rtmning velocity, temperature, crystallinity and theological force is investigated for the take-up velocity over a range of 6 000 - 10 000 m/min. The position of necking point, temperature rise and abrupt increase of crystallinity move closer to the spinneret with the increase of take-up velocity,

  6. Multicolor photonic crystal laser array

    Science.gov (United States)

    Wright, Jeremy B; Brener, Igal; Subramania, Ganapathi S; Wang, George T; Li, Qiming

    2015-04-28

    A multicolor photonic crystal laser array comprises pixels of monolithically grown gain sections each with a different emission center wavelength. As an example, two-dimensional surface-emitting photonic crystal lasers comprising broad gain-bandwidth III-nitride multiple quantum well axial heterostructures were fabricated using a novel top-down nanowire fabrication method. Single-mode lasing was obtained in the blue-violet spectral region with 60 nm of tuning (or 16% of the nominal center wavelength) that was determined purely by the photonic crystal geometry. This approach can be extended to cover the entire visible spectrum.

  7. Simulation study comparing the helmet-chin PET with a cylindrical PET of the same number of detectors

    Science.gov (United States)

    Ahmed, Abdella M.; Tashima, Hideaki; Yoshida, Eiji; Nishikido, Fumihiko; Yamaya, Taiga

    2017-06-01

    There is a growing interest in developing brain PET scanners with high sensitivity and high spatial resolution for early diagnosis of neurodegenerative diseases and studies of brain functions. Sensitivity of the PET scanner can be improved by increasing the solid angle. However, conventional PET scanners are designed based on a cylindrical geometry, which may not be the most efficient design for brain imaging in terms of the balance between sensitivity and cost. We proposed a dedicated brain PET scanner based on a hemispheric shape detector and a chin detector (referred to as the helmet-chin PET), which is designed to maximize the solid angle by increasing the number of lines-of-response in the hemisphere. The parallax error, which PET scanners with a large solid angle tend to have, can be suppressed by the use of depth-of-interaction detectors. In this study, we carry out a realistic evaluation of the helmet-chin PET using Monte Carlo simulation based on the 4-layer GSO detector which consists of a 16  ×  16  ×  4 array of crystals with dimensions of 2.8  ×  2.8  ×  7.5 mm3. The purpose of this simulation is to show the gain in imaging performance of the helmet-chin PET compared with the cylindrical PET using the same number of detectors in each configuration. The sensitivity of the helmet-chin PET evaluated with a cylindrical phantom has a significant increase, especially at the top of the (field-of-view) FOV. The peak-NECR of the helmet-chin PET is 1.4 times higher compared to the cylindrical PET. The helmet-chin PET provides relatively low noise images throughout the FOV compared to the cylindrical PET which exhibits enhanced noise at the peripheral regions. The results show the helmet-chin PET can significantly improve the sensitivity and reduce the noise in the reconstructed images.

  8. A monolithic integrated photonic microwave filter

    Science.gov (United States)

    Fandiño, Javier S.; Muñoz, Pascual; Doménech, David; Capmany, José

    2016-12-01

    Meeting the increasing demand for capacity in wireless networks requires the harnessing of higher regions in the radiofrequency spectrum, reducing cell size, as well as more compact, agile and power-efficient base stations that are capable of smoothly interfacing the radio and fibre segments. Fully functional microwave photonic chips are promising candidates in attempts to meet these goals. In recent years, many integrated microwave photonic chips have been reported in different technologies. To the best of our knowledge, none has monolithically integrated all the main active and passive optoelectronic components. Here, we report the first demonstration of a tunable microwave photonics filter that is monolithically integrated into an indium phosphide chip. The reconfigurable radiofrequency photonic filter includes all the necessary elements (for example, lasers, modulators and photodetectors), and its response can be tuned by means of control electric currents. This is an important step in demonstrating the feasibility of integrated and programmable microwave photonic processors.

  9. Macroporous Monolithic Polymers: Preparation and Applications

    Directory of Open Access Journals (Sweden)

    Cecilia Inés Alvarez Igarzabal

    2009-12-01

    Full Text Available In the last years, macroporous monolithic materials have been introduced as a new and useful generation of polymers used in different fields. These polymers may be prepared in a simple way from a homogenous mixture into a mold and contain large interconnected pores or channels allowing for high flow rates at moderate pressures. Due to their porous characteristics, they could be used in different processes, such as stationary phases for different types of chromatography, high-throughput bioreactors and in microfluidic chip applications. This review reports the contributions of several groups working in the preparation of different macroporous monoliths and their modification by immobilization of specific ligands on the products for specific purposes.

  10. Monolithic pixel detectors for high energy physics

    CERN Document Server

    Snoeys, W

    2013-01-01

    Monolithic pixel detectors integrating sensor matrix and readout in one piece of silicon have revolutionized imaging for consumer applications, but despite years of research they have not yet been widely adopted for high energy physics. Two major requirements for this application, radiation tolerance and low power consumption, require charge collection by drift for the most extreme radiation levels and an optimization of the collected signal charge over input capacitance ratio ( Q / C ). It is shown that monolithic detectors can achieve Q / C for low analog power consumption and even carryout the promise to practically eliminate analog power consumption, but combining suf fi cient Q / C , collection by drift, and integration of readout circuitry within the pixel remains a challenge. An overview is given of different approaches to address this challenge, with possible advantages and disadvantages.

  11. Development of a PET Insert for simultaneously small animal PET/MRI

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yingjie; Zhang, Zhiming; Li, Daowu; Liu, Shuangquan; Wang, Peilin; Feng, Baotong; Chai, Pei; Wei, Long [Division of Nuclear Technology and Applications, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049 (China); Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing, 100049 (China)

    2015-05-18

    PET/MR is a new multi-modality imaging system which provide both structural and functional information with good soft tissue imaging ability and no ionizing radiation. In recent years, PET/MR is under major progress because of the development of silicon photomultipliers (SiPM). The goal of this study is to develop a MRI compatible PET insert based on SiPM and LYSO scintillator. The PET system was constituted by the detector ring, electronics and software. The detector ring consists of 16 detector module. The inner diameter of the ring was 151 mm, the external diameter was 216 mm, which was big enough for small animal research, e.g. rat, rabbit and tupaia. The sensor of each module was 2*2 SensL SPMArraySL, coupled with an array of 14 x 14 LYSO crystals, each crystal measuring 2 mm x 2 mm 10 mm. The detector was encapsulated in a copper box for light and magnetic shielding. Resister charge multiplexing circuit was used in the front end electronics. Each detector output 8X and 8Y position signals. One summed timing signal was extracted from the common cathode of all 64 channels. All these signals were transmitted to digital electronic board by a 3 m long coaxial cable from inside of the MR to the outside. Each digital electronic board handled 8 detector modules based on FPGA to obtain the timing, position and energy information of a single event. And then these single events were sent to the coincidence processing board to produce coincidence packets which are prepared for further processing. A 0.2mCi 68Ge line source was used to do the preliminary imaging test. The image was reconstructed by 3D-OSEM algorithm. The initial result proved the system to be feasible as a PET. FDG phantom imaging and simultaneous PET/MR imaging are in progress.

  12. Update On Monolithic Fuel Fabrication Development

    Energy Technology Data Exchange (ETDEWEB)

    C. R Clark; J. M. Wight; G. C. Knighton; G. A. Moore; J. F. Jue

    2005-11-01

    Efforts to develop a viable monolithic research reactor fuel plate have continued at Idaho National Laboratory. These efforts have concentrated on both fabrication process refinement and scale-up to produce full sized fuel plates. Advancements have been made in the production of U-Mo foil including full sized foils. Progress has also been made in the friction stir welding and transient liquid phase bonding fabrication processes resulting in better bonding, more stable processes and the ability to fabricate larger fuel plates.

  13. FLUIDIZED BED STEAM REFORMER MONOLITH FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Jantzen, C

    2006-12-22

    Fluidized Bed Steam Reforming (FBSR) is being considered as an alternative technology for the immobilization of a wide variety of aqueous high sodium containing radioactive wastes at various DOE facilities in the United States. The addition of clay, charcoal, and a catalyst as co-reactants converts aqueous Low Activity Wastes (LAW) to a granular or ''mineralized'' waste form while converting organic components to CO{sub 2} and steam, and nitrate/nitrite components, if any, to N{sub 2}. The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage-like structures that atomically bond radionuclides like Tc-99 and anions such as SO{sub 4}, I, F, and Cl. The granular product has been shown to be as durable as LAW glass. Shallow land burial requires that the mineralized waste form be able to sustain the weight of soil overburden and potential intrusion by future generations. The strength requirement necessitates binding the granular product into a monolith. FBSR mineral products were formulated into a variety of monoliths including various cements, Ceramicrete, and hydroceramics. All but one of the nine monoliths tested met the <2g/m{sup 2} durability specification for Na and Re (simulant for Tc-99) when tested using the Product Consistency Test (PCT; ASTM C1285). Of the nine monoliths tested the cements produced with 80-87 wt% FBSR product, the Ceramicrete, and the hydroceramic produced with 83.3 wt% FBSR product, met the compressive strength and durability requirements for an LAW waste form.

  14. Monolithically integrated interferometer for optical displacement measurement

    Science.gov (United States)

    Hofstetter, Daniel; Zappe, Hans P.

    1996-01-01

    We discuss the fabrication of a monolithically integrated optical displacement sensors using III-V semiconductor technology. The device is configured as a Michelson interferometer and consists of a distributed Bragg reflector laser, a photodetector and waveguides forming a directional coupler. Using this interferometer, displacements in the 100 nm range could be measured at distances of up to 45 cm. We present fabrication, device results and characterization of the completed interferometer, problems, limitations and future applications will also be discussed.

  15. An overview of monolithic zirconia in dentistry

    Directory of Open Access Journals (Sweden)

    Özlem Malkondu

    2016-07-01

    Full Text Available Zirconia restorations have been used successfully for years in dentistry owing to their biocompatibility and good mechanical properties. Because of their lack of translucency, zirconia cores are generally veneered with porcelain, which makes restorations weaker due to failure of the adhesion between the two materials. In recent years, all-ceramic zirconia restorations have been introduced in the dental sector with the intent to solve this problem. Besides the elimination of chipping, the reduced occlusal space requirement seems to be a clear advantage of monolithic zirconia restorations. However, scientific evidence is needed to recommend this relatively new application for clinical use. This mini-review discusses the current scientific literature on monolithic zirconia restorations. The results of in vitro studies suggested that monolithic zirconia may be the best choice for posterior fixed partial dentures in the presence of high occlusal loads and minimal occlusal restoration space. The results should be supported with much more in vitro and particularly in vivo studies to obtain a final conclusion.

  16. Monolithic Ytterbium All-single-mode Fiber Laser with Direct Fiber-end Delivery of nJ-level Femtosecond Pulses

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry

    2008-01-01

    We demonstrate a monolithic, i.e. without any free-space coupling, all-single-mode passively modelocked Yb-fiber laser, with direct fiber-end delivery of 364−405 fs pulses of 4 nJ pulse energy using a low-loss hollow-core photonic crystal fiber compression....

  17. One-Watt level mid-IR output, singly resonant, continuous-wave optical parametric oscillator pumped by a monolithic diode laser

    NARCIS (Netherlands)

    Nieuwenhuis, Albert F.; Lee, Christopher James; Sumpf, Bernd; van der Slot, Petrus J.M.; Erbert, Götz; Boller, Klaus J.

    2010-01-01

    We report more than 1.1 Watt of idler power at 3373 nm in a singly resonant optical parametric oscillator (SRO), directly pumped by a single-frequency monolithic tapered diode laser. The SRO is based on a periodically poled MgO:LiNbO3 crystal in a four mirror cavity and is excited by 8.05 W of 1062

  18. Preparation of imprinted monolithic column under molecular crowding conditions

    Institute of Scientific and Technical Information of China (English)

    Xiao Xia Li; Xin Liu; Li Hong Bai; Hong Quan Duan; Yan Ping Huang; Zhao Sheng Liu

    2011-01-01

    Molecular crowding is a new concept to obtain molecularly imprinted polymers (MIPs) with greater capacity and selectivity. In this work, molecular crowding agent was firstly applied to the preparation of MIPs monolithic column. A new polymerization system based on molecular crowding surrounding was developed to prepare enrofloxacin-imprinted monolith, which was composed of polystyrene and tetrahydrofuran. The result showed that the monolithic MIPs under molecular crowding conditions presented good molecular recognition for enrofloxacin with an imprinting factor of 3.03.

  19. Development of a high resolution module for PET scanners

    Science.gov (United States)

    Stringhini, G.; Pizzichemi, M.; Ghezzi, A.; Stojkovic, A.; Tavernier, S.; Niknejad, T.; Varela, J.; Paganoni, M.; Auffray, E.

    2017-02-01

    Positron Emission Tomography (PET) scanners require high performances in term of spatial resolution and sensitivity to allow early detection of cancer masses. In small animal and organ dedicated PET scanners the Depth of Interaction (DOI) information has to be obtained to avoid parallax errors and to reconstruct high resolution images. In the whole body PET, the DOI information can be useful to correct for the time jitter of the optical photons along the main axis of the scintillator, improving the time performances. In this work we present the development of PET module designed to reach high performance as compared to the current scanners while keeping the complexity of the system reasonably low. The module presented is based on a 64 LYSO (Lutetium-yttrium oxyorthosilicate) crystals matrix and on a 4×4 MPPC (Multi Pixels Photon Counter) array as detector in a 4 to 1 coupling between the crystals and the detector and a single side readout. The lateral surfaces of the crystals are optically treated to be unpolished. The DOI and the energy resolution of the PET module are presented and a fast method to obtain the DOI calibration is discussed.

  20. Finite Element Modeling of Reheat Stretch Blow Molding of PET

    Science.gov (United States)

    Krishnan, Dwarak; Dupaix, Rebecca B.

    2004-06-01

    Poly (ethylene terephthalate) or PET is a polymer used as a packaging material for consumer products such as beverages, food or other liquids, and in other applications including drawn fibers and stretched films. Key features that make it widely used are its transparency, dimensional stability, gas impermeability, impact resistance, and high stiffness and strength in certain preferential directions. These commercially useful properties arise from the fact that PET crystallizes upon deformation above the glass transition temperature. Additionally, this strain-induced crystallization causes the deformation behavior of PET to be highly sensitive to processing conditions. It is thus crucial for engineers to be able to predict its performance at various process temperatures, strain rates and strain states so as to optimize the manufacturing process. In addressing these issues; a finite element analysis of the reheat blow molding process with PET has been carried out using ABAQUS. The simulation employed a constitutive model for PET developed by Dupaix and Boyce et al.. The model includes the combined effects of molecular orientation and strain-induced crystallization on strain hardening when the material is deformed above the glass transition temperature. The simulated bottles were also compared with actual blow molded bottles to evaluate the validity of the simulation.

  1. Manufacturing, structure and properties of recycled polyethylene terephthalate /liquid crystal polymer/montmorillonite clay nanocomposites

    Science.gov (United States)

    Japins, Guntis; Berzina, Rita; Zicans, Janis; Merijs Meri, Remo; Ivanova, Tatjana; Kalkis, Valdis; Reinholds, Ingars

    2013-12-01

    Polyethylene terephthalate (PET)/liquid crystal polymer (LCP)/monthmorillonite clay (MMT) compositions were obtained by melt mixing. Their mechanical, structural, rheological and thermal properties were investigated.

  2. Monolithic Lumped Element Integrated Circuit (M2LEIC) Transistors.

    Science.gov (United States)

    INTEGRATED CIRCUITS, *MONOLITHIC STRUCTURES(ELECTRONICS), *TRANSISTORS, CHIPS(ELECTRONICS), FABRICATION, EPITAXIAL GROWTH, ULTRAHIGH FREQUENCY, POLYSILICONS, PHOTOLITHOGRAPHY, RADIOFREQUENCY POWER, IMPEDANCE MATCHING .

  3. Clinical application of PET

    Energy Technology Data Exchange (ETDEWEB)

    Lomena, Francisco [Hospital Clinico Villarroel, Barcelona (Spain). Nuclear Medicine]. E-mail: flomena@clinic.ub.es; Soler, Marina [CETIR Grup Medic. Esplkugues de Llobregat, Barcelona (Spain). PET Unit

    2005-10-15

    Positron emission tomography (PET) is an imaging modality that gives information on tissue metabolism and functionalism, different from other imaging techniques like computed tomography (CT) and magnetic resonance imaging (MRI), which provide anatomical or structural information. PET has reached its development in biomedical research because of its capacity to use analogous compounds of many endogenous substance as tracers, and to measure, in vivo and in a non-invasive way, their consumption by the different organs and tissues of the mammalian body. Fluorodeoxyglucose-F 18 (FDG) PET has been proven to be a tracer adequate for clinical use in oncology and in many neurological diseases, with an excellent cost-efficiency ratio. The current PET-CT scanners can come to be the best tools for exploring patients who suffer from cancer.(author)

  4. Combined PET/MRI

    DEFF Research Database (Denmark)

    Bailey, D. L.; Pichler, B. J.; Gückel, B.

    2015-01-01

    This paper summarises key themes and discussions from the 4th international workshop dedicated to the advancement of the technical, scientific and clinical applications of combined positron emission tomography (PET)/magnetic resonance imaging (MRI) systems that was held in Tübingen, Germany, from...... February 23 to 27, 2015. Specifically, we summarise the three days of invited presentations from active researchers in this and associated fields augmented by round table discussions and dialogue boards with specific topics. These include the use of PET/MRI in cardiovascular disease, paediatrics, oncology......, neurology and multi-parametric imaging, the latter of which was suggested as a key promoting factor for the wider adoption of integrated PET/MRI. Discussions throughout the workshop and a poll taken on the final day demonstrated that attendees felt more strongly that PET/MRI has further advanced in both...

  5. Crystallization Behavior of Copolymer Poly (ethylene terephthalate/isophthalate) (IPET)

    Institute of Scientific and Technical Information of China (English)

    顾书英; 肖茹; 顾利霞

    2001-01-01

    The non-isothermal crystallization kinetics, isothermal crystallization and the morphology of crystals of the copolymer poly (ethylene terephthalate/ isophthalate )(IPET) were studied by DSC and polarized-light microscopy in this paper. DSC results indicate that the glass transition temperature Tg of IPET is slightly lower than that of poly(ethylene terephthalate) (PET), but the melting temperature Tm and the crystallization temperature Tc of PET and IPET have much difference.The difference of Tc between PET and IPET2 is about 7℃, and the difference of Tm between PET and IPET2 is about 16℃. From the kinetics analysis of the crystallization, the crystallization mechanism of all samples is of three-dimension spherulitic growth from instantaneous nuclei and the incorporation of isophthalate (IPA) decreases the crystallization rate of IPET greatly. The isothermal results indicate that the morphologies of PET and IPET crystals are all spherulite, which is in conformity to the results of nonisothermal dynamic crystallization. At the same time,the spherulite of IPET grows slower and has longer incubation time than the spherulite of PET under the same crystallization condition.

  6. PET studies in epilepsy.

    Science.gov (United States)

    Sarikaya, Ismet

    2015-01-01

    Various PET studies, such as measurements of glucose, serotonin and oxygen metabolism, cerebral blood flow and receptor bindings are availabe for epilepsy. (18)Fluoro-2-deoxyglucose ((18)F-FDG) PET imaging of brain glucose metabolism is a well established and widely available technique. Studies have demonstrated that the sensitivity of interictal FDG-PET is higher than interictal SPECT and similar to ictal SPECT for the lateralization and localization of epileptogenic foci in presurgical patients refractory to medical treatments who have noncontributory EEG and MRI. In addition to localizing epileptogenic focus, FDG-PET provide additional important information on the functional status of the rest of the brain. The main limitation of interictal FDG-PET is that it cannot precisely define the surgical margin as the area of hypometabolism usually extends beyond the epileptogenic zone. Various neurotransmitters (GABA, glutamate, opiates, serotonin, dopamine, acethylcholine, and adenosine) and receptor subtypes are involved in epilepsy. PET receptor imaging studies performed in limited centers help to understand the role of neurotransmitters in epileptogenesis, identify epileptic foci and investigate new treatment approaches. PET receptor imaging studies have demonstrated reduced (11)C-flumazenil (GABAA-cBDZ) and (18)F-MPPF (5-HT1A serotonin) and increased (11)C-cerfentanil (mu opiate) and (11)C-MeNTI (delta opiate) bindings in the area of seizure. (11)C-flumazenil has been reported to be more sensitive than FDG-PET for identifying epileptic foci. The area of abnormality on GABAAcBDZ and opiate receptor images is usually smaller and more circumscribed than the area of hypometabolism on FDG images. Studies have demonstrated that (11)C-alpha-methyl-L-tryptophan PET (to study synthesis of serotonin) can detect the epileptic focus within malformations of cortical development and helps in differentiating epileptogenic from non-epileptogenic tubers in patients with tuberous

  7. PET/CT Artifacts

    OpenAIRE

    Blodgett, Todd M.; Mehta, Ajeet S.; Mehta, Amar S.; Laymon, Charles M; Carney, Jonathan; Townsend, David W.

    2011-01-01

    There are several artifacts encountered in PET/CT imaging, including attenuation correction (AC) artifacts associated with using CT for attenuation correction. Several artifacts can mimic a 2-deoxy-2-[18F] fluoro-D-glucose (FDG) avid malignant lesions and therefore recognition of these artifacts is clinically relevant. Our goal was to identify and characterize these artifacts and also discuss some protocol variables that may affect image quality in PET/CT.

  8. PET and PET/CT in endocrine tumours

    Energy Technology Data Exchange (ETDEWEB)

    Dudczak, Robert [Department of Nuclear Medicine, Medical University of Vienna (Austria)], E-mail: robert.dudczak@meduniwien.ac.at; Traub-Weidinger, Tatjana [Department of Nuclear Medicine, Medical University of Vienna (Austria)

    2010-03-15

    Functional information provided by PET tracers together with the superior image quality and the better data quantification by PET technology had a changing effect on the significance of nuclear medicine in medical issues. Recently introduced hybrid PET/CT systems together with the introduction of novel PET radiopharmaceuticals have contributed to the fact that nuclear medicine has become a growing diagnostic impact on endocrinology. In this review imaging strategies, different radiopharmaceuticals including the basic mechanism of their cell uptake, and the diagnostic value of PET and PET/CT in endocrine tumours except differentiated thyroid carcinomas will be discussed.

  9. Cascaded Brillouin lasing in monolithic barium fluoride whispering gallery mode resonators

    CERN Document Server

    Lin, Guoping; Saleh, Khaldoun; Martinenghi, Romain; Beugnot, Jean-Charles; Sylvestre, Thibaut; Chembo, Yanne K

    2015-01-01

    We report the observation of stimulated Brillouin scattering and lasing at 1550~nm in barium fluoride (BaF$_2$) crystal. Brillouin lasing was achieved with ultra-high quality ($Q$) factor monolithic whispering gallery mode (WGM) mm-size disk resonators. Overmoded resonators were specifically used to provide cavity resonances for both the pump and all Brillouin Stokes waves. Single and multiple Brillouin Stokes radiations with frequency shift ranging from $8.2$ GHz up to $49$ GHz have been generated through cascaded Brillouin lasing. BaF$_2$ resonator-based Brillouin lasing can find potential applications for high-coherence lasers and microwave photonics.

  10. Detector characterization for an inline PET scanner in hadrontherapy

    Energy Technology Data Exchange (ETDEWEB)

    Taverne, Marina [IPNL, Universite Claude Bernard Lyon 1, 4 rue Enrico Fermi, 69100 Villeurbanne (France); Boutemeur, Madjid [IPNL, Universite Claude Bernard Lyon 1, 4 rue Enrico Fermi, 69100 Villeurbanne (France); Buthod, Anthony [IPNL, Universite Claude Bernard Lyon 1, 4 rue Enrico Fermi, 69100 Villeurbanne (France); Guigues, Laurent [CREATIS, INSA Lyon, avenue Albert Einstein, 69100 Villeurbanne (France); Henriquet, Pierre [IPNL, Universite Claude Bernard Lyon 1, 4 rue Enrico Fermi, 69100 Villeurbanne (France); Lollierou, Julien [IPNL, Universite Claude Bernard Lyon 1, 4 rue Enrico Fermi, 69100 Villeurbanne (France); Ricol, Marie-Charlotte [IPNL, Universite Claude Bernard Lyon 1, 4 rue Enrico Fermi, 69100 Villeurbanne (France); Rosset-Lanchet, Remi [IPNL, Universite Claude Bernard Lyon 1, 4 rue Enrico Fermi, 69100 Villeurbanne (France); Roubin, Mathieu [IPNL, Universite Claude Bernard Lyon 1, 4 rue Enrico Fermi, 69100 Villeurbanne (France); Saidi, Reda [IPNL, Universite Claude Bernard Lyon 1, 4 rue Enrico Fermi, 69100 Villeurbanne (France); Sappey-Marinier, Dominique [CREATIS, INSA Lyon, avenue Albert Einstein, 69100 Villeurbanne (France); Testa, Etienne [IPNL, Universite Claude Bernard Lyon 1, 4 rue Enrico Fermi, 69100 Villeurbanne (France)]. E-mail: taverne@ipnl.in2p3.fr

    2007-02-01

    Our group at the 'Institut de Physique Nucleaire de Lyon' (IPNL) is working on physics and detectors for medical imaging. We are presently developing a small animal Positron Emission Tomograph (PET) scanner prototype with an innovative slow control and data acquisition features, for a demonstration purpose and within the crystal clear international collaboration. We also investigate a feasibility study of an online PET dedicated for inline and in situ dose deposition control in hadrontherapy. Here, we present the characterization setup and method we used to calibrate the detector heads of our PET prototype. Each of these heads consists of a single block continuous scintillating LySO crystal coupled to a multi-anode photomultiplier equipped with its proper acquisition readout chain.

  11. Monolith-Supported Amine-Functionalized Mg2(dobpdc) Adsorbents for CO2 Capture.

    Science.gov (United States)

    Darunte, Lalit A; Terada, Yuri; Murdock, Christopher R; Walton, Krista S; Sholl, David S; Jones, Christopher W

    2017-05-24

    The potential of using an amine-functionalized metal organic framework (MOF), mmen-M2(dobpdc) (M = Mg and Mn), supported on a structured monolith contactor for CO2 capture from simulated flue gas is explored. The stability of the unsupported MOF powders under humid conditions is explored using nitrogen physisorption and X-ray diffraction analysis before and after exposure to humidity. Based on its superior stability to humidity, mmen-Mg2(dobpdc) is selected for further growth on a honeycomb cordierite monolith that is wash-coated with α-alumina. A simple approach for the synthesis of an Mg2(dobpdc) MOF film using MgO nanoparticles as the metal precursor is used. Rapid drying of MgO on the monolith surface followed by a hydrothermal treatment is demonstrated to allow for the synthesis of a MOF film with good crystallite density and favorable orientation of the MOF crystals. The CO2 adsorption behavior of the monolith-supported mmen-Mg2(dobpdc) material is assessed using 10% CO2 in helium and 100% CO2, demonstrating a CO2 uptake of 2.37 and 2.88 mmol/g, respectively. Excellent cyclic adsorption/desorption performance over multiple cycles is also observed. This is one of the first examples of the deployment of an advanced MOF adsorbent in a scalable, low-pressure drop gas-solid contactor. Such demonstrations are critical to the practical application of MOF materials in adsorptive gas separations, as structured contactors have many practical advantages over packed or fluidized beds.

  12. Effect of pressure on the crystallization behaviour of polyethylene terephthalate

    CERN Document Server

    Li Li; Huang Rui

    2002-01-01

    Crystallized polyethylene terephthalate (PET) samples were obtained at high pressures of 200-400 MPa at a temperature of 603 K, and another group of the samples were made at pressures of 250-350 MPa and different temperatures with a fixed supercooling. The samples were investigated by means of differential scanning calorimetry and scanning electron microscopy. Characterization results suggested that high pressure could increase the crystallization rate and promote the thickening process of PET lamellar crystals.

  13. Selective oxidation of cyclohexene through gold functionalized silica monolith microreactors

    Science.gov (United States)

    Alotaibi, Mohammed T.; Taylor, Martin J.; Liu, Dan; Beaumont, Simon K.; Kyriakou, Georgios

    2016-04-01

    Two simple, reproducible methods of preparing evenly distributed Au nanoparticle containing mesoporous silica monoliths are investigated. These Au nanoparticle containing monoliths are subsequently investigated as flow reactors for the selective oxidation of cyclohexene. In the first strategy, the silica monolith was directly impregnated with Au nanoparticles during the formation of the monolith. The second approach was to pre-functionalize the monolith with thiol groups tethered within the silica mesostructure. These can act as evenly distributed anchors for the Au nanoparticles to be incorporated by flowing a Au nanoparticle solution through the thiol functionalized monolith. Both methods led to successfully achieving even distribution of Au nanoparticles along the length of the monolith as demonstrated by ICP-OES. However, the impregnation method led to strong agglomeration of the Au nanoparticles during subsequent heating steps while the thiol anchoring procedure maintained the nanoparticles in the range of 6.8 ± 1.4 nm. Both Au nanoparticle containing monoliths as well as samples with no Au incorporated were tested for the selective oxidation of cyclohexene under constant flow at 30 °C. The Au free materials were found to be catalytically inactive with Au being the minimum necessary requirement for the reaction to proceed. The impregnated Au-containing monolith was found to be less active than the thiol functionalized Au-containing material, attributable to the low metal surface area of the Au nanoparticles. The reaction on the thiol functionalized Au-containing monolith was found to depend strongly on the type of oxidant used: tert-butyl hydroperoxide (TBHP) was more active than H2O2, likely due to the thiol induced hydrophobicity in the monolith.

  14. ClearPEM: prototype PET device dedicated to breast imaging

    CERN Multimedia

    Joao Varela

    2009-01-01

    Clinical trials have begun in Portugal on a new breast imaging system (ClearPEM) using positron emission tomography (PET). The system, developed by a Portuguese consortium in collaboration with CERN and laboratories participating in the Crystal Clear collaboration, will detect even the smallest tumours and thus help avoid unnecessary biopsies.

  15. A prototype MR insertable brain PET using tileable GAPD arrays.

    Science.gov (United States)

    Hong, Key Jo; Choi, Yong; Jung, Jin Ho; Kang, Jihoon; Hu, Wei; Lim, Hyun Keong; Huh, Yoonsuk; Kim, Sangsu; Jung, Ji Woong; Kim, Kyu Bom; Song, Myung Sung; Park, Hyun-Wook

    2013-04-01

    The aim of this study was to develop a prototype magnetic resonance (MR)-compatible positron emission tomography (PET) that can be inserted into a MR imager and that allows simultaneous PET and MR imaging of the human brain. This paper reports the initial results of the authors' prototype brain PET system operating within a 3-T magnetic resonance imaging (MRI) system using newly developed Geiger-mode avalanche photodiode (GAPD)-based PET detectors, long flexible flat cables, position decoder circuit with high multiplexing ratio, and digital signal processing with field programmable gate array-based analog to digital converter boards. A brain PET with 72 detector modules arranged in a ring was constructed and mounted in a 3-T MRI. Each PET module was composed of cerium-doped lutetium yttrium orthosilicate (LYSO) crystals coupled to a tileable GAPD. The GAPD output charge signals were transferred to preamplifiers using 3 m long flat cables. The LYSO and GAPD were located inside the MR bore and all electronics were positioned outside the MR bore. The PET detector performance was investigated both outside and inside the MRI, and MR image quality was evaluated with and without the PET system. The performance of the PET detector when operated inside the MRI during MR image acquisition showed no significant change in energy resolution and count rates, except for a slight degradation in timing resolution with an increase from 4.2 to 4.6 ns. Simultaneous PET/MR images of a hot-rod and Hoffman brain phantom were acquired in a 3-T MRI. Rods down to a diameter of 3.5 mm were resolved in the hot-rod PET image. The activity distribution patterns between the white and gray matter in the Hoffman brain phantom were well imaged. The hot-rod and Hoffman brain phantoms on the simultaneously acquired MR images obtained with standard sequences were observed without any noticeable artifacts, although MR image quality requires some improvement. These results demonstrate that the

  16. Monolithically integrated quantum dot optical modulator with semiconductor optical amplifier for thousand and original band optical communication

    Science.gov (United States)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Matsumoto, Atsushi; Kawanishi, Tetsuya

    2016-04-01

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed with T-band (1.0 µm waveband) and O-band (1.3 µm waveband) QD optical gain materials for Gbps-order, high-speed optical data generation. The insertion loss due to coupling between the device and the optical fiber was effectively compensated for by the SOA section. It was also confirmed that the monolithic QD-OGM/SOA device enabled >4.8 Gbps optical data generation with a clear eye opening in the T-band. Furthermore, we successfully demonstrated error-free 4.8 Gbps optical data transmissions in each of the six wavelength channels over a 10-km-long photonic crystal fiber using the monolithic QD-OGM/SOA device in multiple O-band wavelength channels, which were generated by the single QD gain chip. These results suggest that the monolithic QD-OGM/SOA device will be advantageous in ultra-broadband optical frequency systems that utilize the T+O-band for short- and medium-range optical communications.

  17. Progress on photonic crystals

    CERN Document Server

    Lecoq, P; Gundacker, S; Hillemanns, H; Jarron, P; Knapitsch, A; Leclercq, J L; Letartre, X; Meyer, T; Pauwels, K; Powolny, F; Seassal, C

    2010-01-01

    The renewal of interest for Time of Flight Positron Emission Tomography (TOF PET) has highlighted the need for increasing the light output of scintillating crystals and in particular for improving the light extraction from materials with a high index of refraction. One possible solution to overcome the problem of total internal reflection and light losses resulting from multiple bouncing within the crystal is to improve the light extraction efficiency at the crystal/photodetector interface by means of photonic crystals, i.e. media with a periodic modulation of the dielectric constant at the wavelength scale. After a short reminder of the underlying principles this contribution proposes to present the very encouraging results we have recently obtained on LYSO pixels and the perspectives on other crystals such as BGO, LuYAP and LuAG. These results confirm the impressive predictions from our previously published Monte Carlo simulations. A detailed description of the sample preparation procedure is given as well ...

  18. Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders

    NARCIS (Netherlands)

    De Kanter, J.L.C.G.

    2006-01-01

    Summary accompanying the thesis: Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders by Jens de Kanter This thesis presents the investigation of the crush behaviour of both monolithic aluminium cylinders and externally fibre reinforced aluminium cylinders. The research is based

  19. A Monolithic Perovskite Structure for Use as a Magnetic Regenerator

    DEFF Research Database (Denmark)

    Pryds, Nini; Clemens, Frank; Menon, Mohan

    2011-01-01

    A La0.67Ca0.26Sr0.07Mn1.05O3 (LCSM) perovskite was prepared for the first time as a ceramic monolithic regenerator used in a regenerative magnetic refrigeration device. The parameters influencing the extrusion process and the performance of the regenerator, such as the nature of the monolith paste...

  20. Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders

    NARCIS (Netherlands)

    De Kanter, J.L.C.G.

    2006-01-01

    Summary accompanying the thesis: Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders by Jens de Kanter This thesis presents the investigation of the crush behaviour of both monolithic aluminium cylinders and externally fibre reinforced aluminium cylinders. The research is based

  1. Hydrogel coated monoliths for enzymatic hydrolysis of penicillin G

    NARCIS (Netherlands)

    De Lathouder, K.M.; Smeltink, M.W.; Straathof, A.J.J.; Paasman, M.A.; Van de Sandt, E.J.A.X.; Kapteijn, F.; Moulijn, J.A.

    2008-01-01

    The objective of this work was to develop a hydrogel-coated monolith for the entrapment of penicillin G acylase (E. coli, PGA). After screening of different hydrogels, chitosan was chosen as the carrier material for the preparation of monolithic biocatalysts. This protocol leads to active immobilize

  2. A new large area monolithic silicon telescope

    CERN Document Server

    Tudisco, S; Cabibbo, M; Cardella, G; De Geronimo, G; Di Pietro, A; Fallica, G; Figuera, P; Musumarra, A; Papa, M; Pappalardo, G S; Rizzo, F; Valvo, G

    1999-01-01

    A new prototype of large area (20x20 mm sup 2) monolithic silicon telescope with an ultrathin DELTA E stage (1 mu m) has been built and tested. A particular mask for the ground electrode has been developed to improve the charge collection reducing the induction between the E and DELTA E stages. A special designed preamplifier has been used for the readout of the signal from the DELTA E stage to overcome the problem of the large input capacitance (40 nF). A rather low energy threshold charge discrimination has been obtained. Small side effects due to the electric field deformation near the ground electrode were observed and quantified.

  3. Monolithic aerogels with nanoporous crystalline phases

    Science.gov (United States)

    Daniel, Christophe; Guerra, Gaetano

    2015-05-01

    High porosity monolithic aerogels with nanoporous crystalline phases can be obtained from syndiotactic polystyrene and poly(2,6-dimethyl-1,4-phenylene)oxide thermoreversible gels by removing the solvent with supercritical CO2. The presence of crystalline nanopores in the aerogels based on these polymers allows a high uptake associated with a high selectivity of volatile organic compounds from vapor phase or aqueous solutions even at very low activities. The sorption and the fast kinetics make these materials particularly suitable as sorption medium to remove traces of pollutants from water and moist air.

  4. Medical application of PET technology

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sang Moo; Choi, C. W.; An, S. H.; Woo, K. S.; Chung, W. S.; Yang, S. D.; Jun, G. S. and others

    1999-04-01

    We performed following studies using PET technology: 1. Clinical usefulness of [{sup 18}F]FDG whole body PET in malignant disease 2. Clinical usefulness of quantitative evaluation of F-18-FDG 3. Pilot study of C-11 methionine PET in brain tumor 4. PET study in patients with Parkinson's disease 5. A study on the clinical myocardial PET image. PET gives various metabolic information for the living human body, and is very important, new diagnostic modality. The PET study will give us the information of cancer patients such as early detection of cancer, staging, recurrence detection and characterization of cancer. The quantitative analysis using PET could be applied to evaluate the pathophysiology of various diseases and develop new drugs and develop new radiopharmaceuticals.

  5. PET applications in pediatrics

    Energy Technology Data Exchange (ETDEWEB)

    Shulkin, B. L. [Ann Arbor, Univ. of Michigan Medical Center (United States). Pediatric Nuclear Medicine Section

    1997-12-01

    This article summarizes the major PET studies which have been performed in pediatric patients to elucidate and characterize diseases and normal development. Issues special for the application of the technique in children, such as dosimetry, patient preparation, and image acquisition are discussed. Studies of central nervous system (CNS) development and pathology, including epilepsy, intraventricular hemorrhage, neonatal asphyxia, tumors, and effects on the CNS from treatment of other tumors are reviewed. These have contributed information fundamental to their understanding of CNS development and pathology. PET investigations into the pathophysiology of congenital heart disease have begun and hold great promise to aid their understanding of these conditions. The second major area in which PET has been applied is the study of non CNS neoplasms. Neuroblastoma has been investigated with tracers which explore basic biochemical features which characterize this tumor, as well as with tracers which explore biochemical events relatively specific for this malignancy. Other common and uncommon tumors of childhood are discussed. The PET technique has been shown useful for answering questions of clinical relevance for the management of these uncommon neoplasms. PET is likely to continue to aid their understanding of many pediatric diseases and may gain more widespread clinical acceptance as the technology continues to disseminate rapidly.

  6. Monolithic columns in plant proteomics and metabolomics.

    Science.gov (United States)

    Rigobello-Masini, Marilda; Penteado, José Carlos Pires; Masini, Jorge Cesar

    2013-03-01

    Since "omics" techniques emerged, plant studies, from biochemistry to ecology, have become more comprehensive. Plant proteomics and metabolomics enable the construction of databases that, with the help of genomics and informatics, show the data obtained as a system. Thus, all the constituents of the system can be seen with their interactions in both space and time. For instance, perturbations in a plant ecosystem as a consequence of application of herbicides or exposure to pollutants can be predicted by using information gathered from these databases. Analytical chemistry has been involved in this scientific evolution. Proteomics and metabolomics are emerging fields that require separation, identification, and quantification of proteins, peptides, and small molecules of metabolites in complex biological samples. The success of this work relies on efficient chromatographic and electrophoretic techniques, and on mass spectrometric detection. This paper reviews recent developments in the use of monolithic columns, focusing on their applications in "top-down" and "bottom-up" approaches, including their use as supports for immobilization of proteolytic enzymes and their use in two-dimensional and multidimensional chromatography. Whereas polymeric columns have been predominantly used for separation of proteins and polypeptides, silica-based monoliths have been more extensively used for separation of small molecules of metabolites. Representative applications in proteomics and in analysis of plant metabolites are given and summarized in tables.

  7. Growth techniques for monolithic YBCO solenoidal magnets

    Energy Technology Data Exchange (ETDEWEB)

    Scruggs, S.J. [Texas Center for Superconductivity at University of Houston, 4800 Calhoun, Houston, TX 77204 (United States)]. E-mail: Sscruggs2@uh.edu; Putman, P.T. [Texas Center for Superconductivity at University of Houston, 4800 Calhoun, Houston, TX 77204 (United States); Fang, H. [Texas Center for Superconductivity at University of Houston, 4800 Calhoun, Houston, TX 77204 (United States); Alessandrini, M. [Texas Center for Superconductivity at University of Houston, 4800 Calhoun, Houston, TX 77204 (United States); Salama, K. [Texas Center for Superconductivity at University of Houston, 4800 Calhoun, Houston, TX 77204 (United States)

    2006-10-01

    The possibility of growing large single domain YBCO solenoids by the use of a large seed has been investigated. There are two known methods for producing a similar solenoid. This first is a conventional top seeded melt growth process followed by a post processing machining step to create the bore. The second involves using multiple seeds spaced around the magnet bore. The appeal of the new technique lies in decreasing processing time compared to the single seed technique, while avoiding alignment problems found in the multiple seeding technique. By avoiding these problems, larger diameter monoliths can be produced. Large diameter monoliths are beneficial because the maximum magnetic field produced by a trapped field magnet is proportional to the radius of the sample. Furthermore, the availability of trapped field magnets with large diameter could enable their use in applications that traditionally have been considered to require wound electromagnets, such as beam bending magnets for particle accelerators or electric propulsion. A comparison of YBCO solenoids grown by the use of a large seed and grown by the use of two small seeds simulating multiple seeding is made. Trapped field measurements as well as microstructure evaluation were used in characterization of each solenoid. Results indicate that high quality growth occurs only in the vicinity of the seeds for the multiple seeded sample, while the sample with the large seeded exhibited high quality growth throughout the entire sample.

  8. High surface area, high permeability carbon monoliths

    Energy Technology Data Exchange (ETDEWEB)

    Lagasse, R.R.; Schroeder, J.L. [Sandia National Labs., Albuquerque, NM (United States). Organic Materials Processing Dept.

    1994-12-31

    The goal of this work is to prepare carbon monoliths having precisely tailored pore size distribution. Prior studies have demonstrated that poly(acrylonitrile) can be processed into a precursor having tailored macropore structure. Since the macropores were preserved during pyrolysis, this synthetic process provided a route to porous carbon having macropores with size =0.1 to 10{mu}m. No micropores of size <2 nm could be detected in the carbon, however, by nitrogen adsorption. In the present work, the authors have processed a different polymer, poly(vinylidene chloride) into a macroporous precursor, Pyrolysis produced carbon monoliths having macropores derived from the polymer precursor as well as extensive microporosity produced during the pyrolysis of the polymer. One of these carbons had BET surface area of 1,050 m{sup 2}/g and about 1.2 cc/g total pore volume, with about 1/3 of the total pore volume in micropores and the remainder in 1{mu}m macropores. No mesopores in the intermediate size range could be detected by nitrogen adsorption. Carbon materials having high surface area as well as micron size pores have potential applications as electrodes for double layer supercapacitors containing liquid electrolyte, or as efficient media for performing chemical separations.

  9. Hydrothermal method for preparing calcium phosphate monoliths

    Directory of Open Access Journals (Sweden)

    García Carrodeguas Raúl

    2003-01-01

    Full Text Available A new hydrothermal route for preparing biphasic calcium phosphate monoliths is proposed. Firstly, a slurry of beta-tricalcium phosphate/ortho-phosphoric acid (b-TCP/H3PO4 is cast into the desired final shape and size to obtain a block composed of dicalcium phosphate dihydrate (DCPD and b-TCP. This block is then treated in 1.0 M Na2HPO4 at 60 °C in order to hydrolyze the DCPD into Ca10-x(HPO4x(PO4 6-x(OH2-x (CDHA and Ca8H2(PO46 .5H2O (OCP. The result is a monolithic piece which preserves the initial shape and size, but which is composed instead of CDHA, OCP, and b-TCP. During the initial stage, when the pH is slightly alkaline, the product of DCPD hydrolysis is CDHA. However, when a neutral or slightly acidic pH is reached OCP is formed. Test samples processed by this method showed complete conversion of DCPD into CDHA and OCP after 112 h of hydrolysis, and with a compressive strength of 16.2 MPa, similar to cancellous bone.

  10. Catastrophic failure of a monolithic zirconia prosthesis.

    Science.gov (United States)

    Chang, Jae-Seung; Ji, Woon; Choi, Chang-Hoon; Kim, Sunjai

    2015-02-01

    Recently, monolithic zirconia restorations have received attention as an alternative to zirconia veneered with feldspathic porcelain to eliminate chipping failures of veneer ceramics. In this clinical report, a patient with mandibular edentulism received 4 dental implants in the interforaminal area, and a screw-retained monolithic zirconia prosthesis was fabricated. The patient also received a maxillary complete removable dental prosthesis over 4 anterior roots. At the 18-month follow-up, all of the zirconia cylinders were seen to be fractured, and the contacting abutment surfaces had lost structural integrity. The damaged abutments were replaced with new abutments, and a new prosthesis was delivered with a computer-assisted design and computer-assisted manufacturing fabricated titanium framework with denture teeth and denture base resins. At the 6-month recall, the patient did not have any problems. Dental zirconia has excellent physical properties; however, care should be taken to prevent excessive stresses on the zirconia cylinders when a screw-retained zirconia restoration is planned as a definitive prosthesis.

  11. PET imaging in multiple sclerosis

    NARCIS (Netherlands)

    Faria, Daniele de Paula; Copray, Sjef; Buchpiguel, Carlos; Dierckx, Rudi; de Vries, Erik

    2014-01-01

    Positron emission tomography (PET) is a non-invasive technique for quantitative imaging of biochemical and physiological processes in animals and humans. PET uses probes labeled with a radioactive isotope, called PET tracers, which can bind to or be converted by a specific biological target and thus

  12. Cognitive dysfunction in senior pets.

    Science.gov (United States)

    Crowell-Davis, Sharon L

    2008-02-01

    Aging pets can experience declines in memory, learning, perception, and awareness. These pets may be disoriented, forget previously learned behaviors, develop new fears and anxiety, or change their interactions with people. When these changes are due to cognitive dysfunction, behavioral and environmental adjustments along with medical therapy can slow the progression and keep pets active longer.

  13. Optimization of PET scanner geometry

    Energy Technology Data Exchange (ETDEWEB)

    Adam, Lars-Eric; Karp, J.S. [Univ. of Pennsylvania, Department of Radiology, Philadelphia, PA (United States)

    2000-12-01

    Modern positron emission tomographs (PET), when used for 3D imaging, have a wide open gantry without intra plane septa and only little shielding. In order to reduce the scatter contamination from activity inside and outside the field-of-view (FOV), and to block radiation originating from activity outside-the-FOV, we have investigated the implementation of septa and additional patient shielding on our existing whole body PET scanner. A series of Monte Carlo simulations, based on EGS4, were performed to predict the potential benefits. Our simulations include point and line sources at various radial and axial positions in the FOV of the scanner, and different sized uniform cylinders (up to 100 cm long and 50 cm in diameter). The scanner itself is based on 6 continuous NaI(Tl) crystals, an axial FOV of 25.6 cm, a ring diameter of 90 cm, and a transaxial FOV of 56 cm. The results show that septa can reduce the relative scatter fraction and effectively block radiation from outside-the-FOV, but they also reduce the sensitivity for true events, leading to a decrease of the trues-to-singles ratio that is not desirable. The use of septa is only advantageous for large objects, if the loss of true events is compensated for by increasing the injected activity. Patient shields that are mounted outside-the-FOV reduce the contamination from scattered and single events without interfering with true events. They are more effective for objects with a small diameter and less effective for objects with a large diameter. (author)

  14. Crystals against cancer

    CERN Multimedia

    2009-01-01

    This is a remarkable example of direct technology transfer from particle physics to medicine. Clinical trials have begun in Portugal on a new medical imaging system for the diagnosis of breast cancer, which uses positron emission tomography (PET). The system, developed by a Portuguese consortium in collaboration with CERN and laboratories participating in the Crystal Clear collaboration, will detect even the smallest tumours and thus help avoid unnecessary biopsies.

  15. PET-CT; PET-CT

    Energy Technology Data Exchange (ETDEWEB)

    Schober, O. [Univeritaetsklinikum Muenster (Germany). Klinik und Poliklinik fuer Nuklearmedizin; Heindel, W. [Univeritaetsklinikum Muenster (Germany). Inst. fuer Klinische Radiologie

    2008-07-01

    Positron emission tomography - computerized tomography (PET-CT) is the fusion of two modern imaging techniques. The book includes the following chapters: 1. fundamentals: radiation protection aspects, radionuclide production, contrast agents, patient preparation, image interpretation; 2. diagnostics of carcinomas: carcinomas in brain, head-throat, thyroid, lungs, intestinal tract, gynecological carcinomas, urinary tract and bladder carcinomas, prostate carcinomas, malignant lymphomas, malignant malinomas, carcinomas in the skeletal system; 3. infections; 4. diagnostics of cardiovascular diseases; 5. diagnostics of neurodegenerative diseases; 6. developments and perspectives, 7. attachments: internet links, glossary, abbreviations.

  16. Clinical application of pet

    Directory of Open Access Journals (Sweden)

    Francisco Lomeña

    2005-10-01

    Full Text Available Positron emission tomography (PET is an imaging modality that gives information on tissue metabolism and functionalism, different from other imaging techniques like computed tomography (CT and magnetic resonance imaging (MRI, which provide anatomical or structural information. PET has reached its development in biomedical research because of its capacity to use analogous compounds of many endogenous substance as tracers, and to measure, in vivo and in a non-invasive way, their consumption by the different organs and tissues of the mammalian body. Fluordeoxyglucose-F18 (FDG PET has been proven to be a tracer adequate for clinical use in oncology and in many neurological diseases, with an excellent cost-efficiency ratio. The current PET-CT scanners can come to be the best tools for exploring patients who suffer from cancer.A tomografia por emissão de pósitrons (PET é uma técnica de diagnóstico por imagem que fornece informação sobre o metabolismo e funcionamento dos tecidos, diferente de outras técnicas de imagens como tomografia computadorizada (TC e ressonância magnética (RM, as quais fornecem informações estruturais ou anatômicas. O PET alcançou seu desenvolvimento em investigação biomédica devido à sua capacidade de usar traçadores análogos a muitas substâncias endógenas e de medir in vivo e de forma não invasiva seu consumo em diferentes órgãos e tecidos dos mamíferos 18Fluordesoxiglicose (FDG PET tem provado ser uma exploração de uso clínico com excelente relação custo benefício em oncologia e em muitas doenças neurológicas. Os atuais tomógrafos por PET-CT podem chegar a ser a melhor ferramenta de diagnóstico nos pacientes que sofrem de câncer.

  17. Monolithic crystalline cladding microstructures for efficient light guiding and beam manipulation in passive and active regimes

    Science.gov (United States)

    Jia, Yuechen; Cheng, Chen; Vázquez de Aldana, Javier R.; Castillo, Gabriel R.; Rabes, Blanca del Rosal; Tan, Yang; Jaque, Daniel; Chen, Feng

    2014-01-01

    Miniature laser sources with on-demand beam features are desirable devices for a broad range of photonic applications. Lasing based on direct-pump of miniaturized waveguiding active structures offers a low-cost but intriguing solution for compact light-emitting devices. In this work, we demonstrate a novel family of three dimensional (3D) photonic microstructures monolithically integrated in a Nd:YAG laser crystal wafer. They are produced by the femtosecond laser writing, capable of simultaneous light waveguiding and beam manipulation. In these guiding systems, tailoring of laser modes by both passive/active beam splitting and ring-shaped transformation are achieved by an appropriate design of refractive index patterns. Integration of graphene thin-layer as saturable absorber in the 3D laser structures allows for efficient passive Q-switching of tailored laser radiations which may enable miniature waveguiding lasers for broader applications. Our results pave a way to construct complex integrated passive and active laser circuits in dielectric crystals by using femtosecond laser written monolithic photonic chips. PMID:25100561

  18. PET performance evaluation of MADPET4: a small animal PET insert for a 7-Tesla MRI scanner.

    Science.gov (United States)

    Omidvari, Negar; Cabello, Jorge; Topping, Geoffrey; Schneider, Florian Roland; Paul, Stephan; Schwaiger, Markus; Ziegler, Sibylle I

    2017-10-04

    MADPET4 is the first small animal PET insert with two layers of individually read out crystals in combination with silicon photomultiplier technology. It has a novel detector arrangement, in which all crystals face the center of field of view transaxially. In this work, the PET performance of MADPET4 was evaluated and compared to other preclinical PET scanners using the NEMA NU 4 measurements, followed by imaging a mouse-size hot-rod resolution phantom and two in vivo simultaneous PET/MRI scans in a 7-T MRI scanner. The insert had a peak sensitivity of 0.49%, using an energy threshold of 350 keV. A uniform transaxial resolution was obtained up to 15 mm radial offset from the axial center, using filtered back-projection with single-slice rebinning. The measured average radial and tangential resolutions (FWHM) were 1.38 mm and 1.39 mm, respectively. The 1.2 mm rods were separable in the hot-rod phantom using an iterative image reconstruction algorithm. The scatter fraction was 7.3% and peak noise equivalent count rate was 15.5 kcps at 65.1 MBq of activity. The FDG uptake in a mouse heart and brain were visible in the two in vivo simultaneous PET/MRI scans without applying image corrections. In conclusion, the insert demonstrated a good overall performance and can be used for small animal multi-modal research applications. © 2017 Institute of Physics and Engineering in Medicine.

  19. Kinetic analysis of dynamic PET data

    Energy Technology Data Exchange (ETDEWEB)

    Knittel, B.

    1983-12-01

    Our goal is to quantify regional physiological processes such as blood flow and metabolism by means of tracer kinetic modeling and positron emission tomography (PET). Compartmental models are one way of characterizing the behavior of tracers in physiological systems. This paper describes a general method of estimating compartmental model rate constants from measurements of the concentration of tracers in blood and tissue, taken at multiple time intervals. A computer program which applies the method is described, and examples are shown for simulated and actual data acquired from the Donner 280-Crystal Positron Tomograph.

  20. KINETICS OF NON-ISOTHERMAL CRYSTALLIZATION

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhiying; CAO Zhenlin

    1990-01-01

    A kinetic equation of non-isothermal crystamzation was derived by extending Avrami's equation to the non-isothermal situation. More crystallization information can be obtained from this kinetic equation. The curves of non-isothermal and isothermal crystallizations were analysed and compared for poly (ethylene terephthalate ) (PET), and the results were discussed.

  1. A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators

    National Research Council Canada - National Science Library

    Kamińska, D; Gajos, A; Czerwiński, E; Alfs, D; Bednarski, T; Białas, P; Curceanu, C; Dulski, K; Głowacz, B; Gupta-Sharma, N; Gorgol, M; Hiesmayr, B C; Jasińska, B; Korcyl, G; Kowalski, P; Krzemień, W; Krawczyk, N; Kubicz, E; Mohammed, M; Niedźwiecki, Sz; Pawlik-Niedźwiecka, M; Raczyński, L; Rudy, Z; Silarski, M; Wieczorek, A; Wiślicki, W; Zgardzińska, B; Zieliński, M; Moskal, P

    2016-01-01

    ...) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals...

  2. PET/MR in oncology

    DEFF Research Database (Denmark)

    Balyasnikova, Svetlana; Löfgren, Johan; de Nijs, Robin

    2012-01-01

    of the challenges inherent in this new technology, but focus on potential applications for simultaneous PET/MR in the field of oncology. Methods and tracers for use with the PET technology will be familiar to most readers of this journal; thus this paper aims to provide a short and basic introduction to a number...... be applied together with PET increasing the amount of information about the tissues of interest. The potential clinical benefit of applying PET/MR in staging, radiotherapy planning and treatment evaluation in oncology, as well as the research perspectives for the use of PET/MR in the development of new...

  3. PET/MR in oncology

    DEFF Research Database (Denmark)

    Balyasnikova, Svetlana; Löfgren, Johan; de Nijs, Robin

    2012-01-01

    of the challenges inherent in this new technology, but focus on potential applications for simultaneous PET/MR in the field of oncology. Methods and tracers for use with the PET technology will be familiar to most readers of this journal; thus this paper aims to provide a short and basic introduction to a number...... be applied together with PET increasing the amount of information about the tissues of interest. The potential clinical benefit of applying PET/MR in staging, radiotherapy planning and treatment evaluation in oncology, as well as the research perspectives for the use of PET/MR in the development of new...

  4. Preparation and Characterization of Temperature-responsive Porous Monoliths

    Institute of Scientific and Technical Information of China (English)

    ZHANG, Rongyue; QI, Li; XIN, Peiyong; YANG, Gengliang; CHEN, Yi

    2009-01-01

    A new temperature-responsive porous monolith has been prepared by surface-initiated activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) grafting poly(N-isopropylacrylamide) (PNIPAAm) within the pores of the porous polymer monolith. The grafting copolymerization was carried out by a method based on a continuous flow-through technique without special deoxygenation procedure needed in the general ATRP. The addition of ascorbic acid could counteract the oxidation effect of oxygen diffusing into the reaction system. The resulting grafted monolith was characterized by a mercury intrusion method and the size of macropore was 3.65 μm, which was suitable for flow through the monolith for HPLC. The thermally responsive property of the grafted monolith was evaluated by HPLC using steroids with various hydrophobicities as probes. Through determination of retention factor of each steroid on the grafted monolith at different temperatures using water as mobile phase, it was found that the slope of the plot of retention factor of each steroid versus the temperature changed around the low critical solution temperature (LCST, 32 ℃) of PNIPAAm in water. It was relative to the grafted PNIPAAm temperature sensitivity that a hydrophobic and hydrophilic alternation would take place around its LCST.Based on this thermally responsive property, the grafted monolith was used as stationary phase for HPLC and to separate the steroids using water as mobile phase by changing the column temperature. As a mobile phase, water is much better than organic solvents concerning the environment.

  5. Influence of different carbon monolith preparation parameters on pesticide adsorption

    Directory of Open Access Journals (Sweden)

    Vukčević Marija

    2013-01-01

    Full Text Available The capacity of carbon monolith for pesticide removal from water, and the mechanism of pesticide interaction with carbon surface were examined. Different carbon monolith samples were obtained by varying the carbonization and activation parameters. In order to examine the role of surface oxygen groups in pesticide adsorption, carbon monolith surface was functionalized by chemical treatment in HNO3, H2O2 and KOH. The surface properties of the obtained samples were investigated by BET surface area, pore size distribution and temperature-programmed desorption. Adsorption of pesticides from aqueous solution onto activated carbon monolith samples was studied by using five pesticides belonging to different chemical groups (acetamiprid, dimethoate, nicosulfuron, carbofuran and atrazine. Presented results show that higher temperature of carbonization and the amount of activating agent allow obtaining microporous carbon monolith with higher amount of surface functional groups. Adsorption properties of the activated carbon monolith were more readily affected by the amount of the surface functional groups than by specific surface area. Results obtained by carbon monolith functionalisation showed that π-π interactions were the main force for adsorption of pesticides with aromatic structure, while acidic groups play an important role in adsorption of pesticides with no aromatic ring in the chemical structure.

  6. Improving the Time Resolution of TOF-PET Detectors by Double-Sided Readout

    NARCIS (Netherlands)

    Seifert, S.; Schaart, D.R.

    2015-01-01

    State-of-the-art scintillation detectors for time-of-flight positron emission tomography (TOF-PET) typically employ scintillation crystals with a high aspect ratio (e.g. 4 ×4 ×22 mm3) read out on one of the small crystal surfaces. This single-sided readout (SSR) geometry may be unfavorable in terms

  7. Improving the Time Resolution of TOF-PET Detectors by Double-Sided Readout

    NARCIS (Netherlands)

    Seifert, S.; Schaart, D.R.

    2015-01-01

    State-of-the-art scintillation detectors for time-of-flight positron emission tomography (TOF-PET) typically employ scintillation crystals with a high aspect ratio (e.g. 4 ×4 ×22 mm3) read out on one of the small crystal surfaces. This single-sided readout (SSR) geometry may be unfavorable in terms

  8. Choosing a Pet

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    THE capital boasts countless markets of all kinds,but some of its insect,bird and pet markets immortalize Beijing culture and folkloric traditions.Don’t miss it! The Huasheng Tianqiao Market,south of the famous Panjiayuan Antique Market, was moved a few years ago and rebuilt in the

  9. I Love Petting Zoos!

    Centers for Disease Control (CDC) Podcasts

    2010-03-23

    This Kidtastics podcast helps children learn about how to stay safe and healthy when visiting petting zoos and other animal exhibits.  Created: 3/23/2010 by Centers for Disease Control and Prevention (CDC).   Date Released: 3/23/2010.

  10. Cold Weather Pet Safety

    Science.gov (United States)

    ... they can be knocked over, potentially starting a fire. Check your furnace before the cold weather sets in to make ... avoided because of the risk of burns or fire. Heated pet mats should also be used ... to burrow, get them back inside quickly because they are showing signs of ...

  11. PET's indsats under lup

    DEFF Research Database (Denmark)

    Hansen, Peer Henrik

    2006-01-01

    En undersøgelseskommission nedsat i 1999. Fem medlemmer skal undersøge PET's efterretningsvirksomhed i forhold til politiske partier, faglige konflikter og politisk ideologiske bevægelser i Danmark under den kolde krig. Kommissionens rapport forventes færdig næste år. Udgivelsesdato: 2. juli 2006...

  12. Pets and Parasites

    Science.gov (United States)

    ... to Be SafeTo avoid dog bites, teach your child how to behave around dogs.December 2010September 2000familydoctor.org editorial staffAvoiding SnakebitesRead Article >>Pets and AnimalsAvoiding SnakebitesLearn how to identify, treat, and ...

  13. PET and PET/CT in malignant melanoma; PET y PET/CT en melanoma maligno

    Energy Technology Data Exchange (ETDEWEB)

    Garcia O, J.R. [Nuclear Medicine and Molecular Imaging PET/CT, Centro Medico ABC, Mexico D.F. (Mexico)

    2007-07-01

    The advantages that it has the PET/CT are: 1. It diminishes mainly positive false lesions. It identifies physiologic accumulate places. 2. It diminishes in smaller grade false negative. Small injuries. Injuries with low grade concentration. Injure on intense activity areas. 3. Precise anatomical localization of accumulate places. 4. Reduction of the acquisition time. (Author)

  14. Birds Kept as Pets

    Science.gov (United States)

    ... Bird Importation website . Choosing a bird Match a bird's attitude, temperament, size, and activity level with your family, ... 2009;135:68-77 Compendium of Measures To Control Chlamydophila psittaci ... Pet Birds (Avian Chlamydiosis), 2010 [PDF – 17 pages] National Association ...

  15. Spatial resolution limits for the isotropic-3D PET detector X’tal cube

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Eiji, E-mail: rush@nirs.go.jp; Tashima, Hideaki; Hirano, Yoshiyuki; Inadama, Naoko; Nishikido, Fumihiko; Murayama, Hideo; Yamaya, Taiga

    2013-11-11

    Positron emission tomography (PET) has become a popular imaging method in metabolism, neuroscience, and molecular imaging. For dedicated human brain and small animal PET scanners, high spatial resolution is needed to visualize small objects. To improve the spatial resolution, we are developing the X’tal cube, which is our new PET detector to achieve isotropic 3D positioning detectability. We have shown that the X’tal cube can achieve 1 mm{sup 3} uniform crystal identification performance with the Anger-type calculation even at the block edges. We plan to develop the X’tal cube with even smaller 3D grids for sub-millimeter crystal identification. In this work, we investigate spatial resolution of a PET scanner based on the X’tal cube using Monte Carlo simulations for predicting resolution performance in smaller 3D grids. For spatial resolution evaluation, a point source emitting 511 keV photons was simulated by GATE for all physical processes involved in emission and interaction of positrons. We simulated two types of animal PET scanners. The first PET scanner had a detector ring 14.6 cm in diameter composed of 18 detectors. The second PET scanner had a detector ring 7.8 cm in diameter composed of 12 detectors. After the GATE simulations, we converted the interacting 3D position information to digitalized positions for realistic segmented crystals. We simulated several X’tal cubes with cubic crystals from (0.5 mm){sup 3} to (2 mm){sup 3} in size. Also, for evaluating the effect of DOI resolution, we simulated several X’tal cubes with crystal thickness from (0.5 mm){sup 3} to (9 mm){sup 3}. We showed that sub-millimeter spatial resolution was possible using cubic crystals smaller than (1.0 mm){sup 3} even with the assumed physical processes. Also, the weighted average spatial resolutions of both PET scanners with (0.5 mm){sup 3} cubic crystals were 0.53 mm (14.6 cm ring diameter) and 0.48 mm (7.8 cm ring diameter). For the 7.8 cm ring diameter, spatial

  16. Passively Q-switched diode-pumped Cr4+:YAG/Nd3+:GdVO4 monolithic microchip laser

    CERN Document Server

    Forget, S; Balembois, F; Georges, P; Landru, N; Feve, J P; Lin, J; Weng, Z; Forget, Sebastien; Druon, Frederic; Balembois, Francois; Georges, Patrick; Landru, Nicolas; Feve, Jean Philippe; Lin, Jiali; Weng, Zhiming

    2006-01-01

    the realization of high repetition rate passively Q-switched monolithic microlaser is a challenge since a decade. To achieve this goal, we report here on the first passively Q-switched diode-pumped microchip laser based on the association of a Nd:GdVO4 crystal and a Cr4+:YAG saturable absorber. The monolithic design consists of 1 mm long 1% doped Nd:GdVO4 optically contacted on a 0.4 mm long Cr4+:YAG leading to a plano-plano cavity. A repetition rate as high as 85 kHz is achieved. The average output power is approximately 400 mW for 2.2 W of absorbed pump power and the pulse length is 1.1 ns.

  17. Preliminary comparison of monolithic and aperture optics for XRMF

    Energy Technology Data Exchange (ETDEWEB)

    Havrilla, G.J.; Worley, C.G.

    1997-08-01

    Comparisons between standard aperture optics and a custom designed monolithic capillary x-ray optic for the Kevex Omicron are presented. The results demonstrate the feasibility of retrofitting an Omicron with a monolithic capillary. Increased flux is observed especially at lower energies which results in an increase in sensitivity and potentially an increase in spatial resolution. Alignment is a critical factor in achieving optimal performance of the monolithic capillary. Further improvements in flux output, spot size and overall sensitivity are expected with better alignment.

  18. On monolithic stability and reinforcement analysis of high arch dams

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Monolithic stability safety and reinforcement based on monolithic stability are very important for arch dam design.In this paper,the issue is addressed based on deformation reinforcement theory.In this approach,plastic complementary energy norm can be taken as safety Index for monolithic stability.According to deformation reinforcement theory,the areas where unbalanced force exists require reinforcement,and the required reinforcement forces are just the unbalanced forces with opposite direction.Results show that areas with unbalanced force mainly concentrate in dam-toes,dam-heels and faults.

  19. Hierarchically Structured Monolithic ZSM-5 through Macroporous Silica Gel Zeolitization

    Institute of Scientific and Technical Information of China (English)

    Lei Qian; Zhao Tianbo; Li Fengyan; Zong Baoning; Tong Yangchuan

    2006-01-01

    The hierarchically structured ZSM-5 monolith was prepared through transforming the skeletons of the macroporous silica gel into ZSM-5 by the steam-assisted conversion method. The morphology and monolithic shapes of macroporous silica gel were well preserved. The hierarchically structured ZSM-5 monolith exhibited the hierarchical porosity, with mesopores and macropores existing inside the macroporous silica gel, and micropores formed by the ZSM-5. The products have been characterized properly by using the XRD, SEM and N2 adsorption-desorption methods.

  20. Preparation of carbon monoliths from orange peel for NOx retention

    Directory of Open Access Journals (Sweden)

    Liliana Giraldo

    2014-12-01

    Full Text Available A series of monoliths are prepared from orange peels and chemically activated with H3PO4, KOH, ZnCl2, and water vapor without a binder. The monoliths were characterized by N2 adsorption-desorption isotherms at 77 K, Boehm titrations and XPS. Thereafter, monoliths were tested for their ability to establish NOx retention. The results show that the retention capacities of NOx were a function of the textural properties and chemistries. The carbons synthesized with ZnCl2 and KOH retained similar amounts of NOx.

  1. A decoupled monolithic projection method for natural convection problems

    Science.gov (United States)

    Pan, Xiaomin; Kim, Kyoungyoun; Lee, Changhoon; Choi, Jung-Il

    2016-06-01

    We propose an efficient monolithic numerical procedure based on a projection method for solving natural convection problems. In the present monolithic method, the buoyancy, linear diffusion, and nonlinear convection terms are implicitly advanced by applying the Crank-Nicolson scheme in time. To avoid an otherwise inevitable iterative procedure in solving the monolithic discretized system, we use a linearization of the nonlinear convection terms and approximate block lower-upper (LU) decompositions along with approximate factorization. Numerical simulations demonstrate that the proposed method is more stable and computationally efficient than other semi-implicit methods, preserving temporal second-order accuracy.

  2. Evaluation of PET performance and MR compatibility of a preclinical PET/MR insert with digital silicon photomultiplier technology

    Energy Technology Data Exchange (ETDEWEB)

    Hallen, Patrick; Schug, David; Wehner, Jakob [Department of Physics of Molecular Imaging Systems, RWTH Aachen University (Germany); Weissler, Bjorn [Department of Chemical Application Research, Philips Research (Germany); Gebhardt, Pierre [Division of Imaging Sciences and Biomedical Engineering, King’s College London (United Kingdom); Goldschmidt, Benjamin [Department of Physics of Molecular Imaging Systems, RWTH Aachen University (Germany); Salomon, Andre [Department of Oncology Solutions, Philips Research (Germany); Duppenbecker, Peter [Department of Physics of Molecular Imaging Systems, RWTH Aachen University (Germany); Kiessling, Fabian [Institute for Experimental Molecular Imaging, RWTH Aachen University (Germany); Schultz, Volkmar [Department of Physics of Molecular Imaging Systems, RWTH Aachen University (Germany)

    2015-05-18

    In this work we present detailed characterizations of our preclinical high resolution PET/MR insert based on the Hyperion-IID platform. The PET/MR insert consists of a ring of 10 singles detection modules, each comprising 2x3 scintillation detector stacks. Each detector stack features a 30x30 pixelated LYSO crystal array with a height of 12 mm and a pitch of 1 mm, coupled via a slit 2 mm light guide to a digital SiPM tile. The PET performance is stable under a wide range of operating points. The spatial resolution is below 1Ä,mm and the CRT reaches 260 or 450 ps depending on trigger settings. The energy resolution is 12.6% FWHM. The characterization of the MR compatibility showed no relevant degradation in PET performance during MRI operation. On the MRI side, we observe a degradation in B0 homogeneity from a VRMS of 0.03 ppm to 0.08 ppm with active shimming, while observing only minor degradations in the B0 field. The noise floor is slightly increased by 2-15% without any observable dependence on the activity. The Z gradients induces an observable eddy current inside the PET inserts which can lead to ghosting artifacts for EPI sequences. However, we don't observe any visible image degradation for widely used anatomical imaging sequences such as gradient echo and turbo spin echo sequences. To prove the viability of our PET/MR insert for in vivo small animal studies, we successfully performed a longitudinal mouse study with subcutaneously injected tumor model cells. The simultaneously acquired PET/MR images provide a high level of anatomical information and soft tissue contrast in the MR layer together with a high resolution image of the FDG tracer distribution in the PET layer.

  3. Preliminary studies of PQS PET detector module for dose verification of carbon beam therapy

    Science.gov (United States)

    Kim, H.-I.; An, S. Jung; Lee, C. Y.; Jo, W. J.; Min, E.; Lee, K.; Kim, Y.; Joung, J.; Chung, Y. H.

    2014-05-01

    PET imaging can be used to verify dose distributions of therapeutic particle beams such as carbon ion beams. The purpose of this study was to develop a PET detector module which was designed for an in-beam PET scanner geometry integrated into a carbon beam therapy system, and to evaluate its feasibility as a monitoring system of patient dose distribution. A C-shaped PET geometry was proposed to avoid blockage of the carbon beam by the detector modules. The proposed PET system consisted of 14 detector modules forming a bore with 30.2 cm inner diameter for brain imaging. Each detector module is composed of a 9 × 9 array of 4.0 mm × 4.0 mm × 20.0 mm LYSO crystal module optically coupled with four 29 mm diameter PMTs using Photomultiplier-quadrant-sharing (PQS) technique. Because the crystal pixel was identified based upon the distribution of scintillation lights of four PMTs, the design of the reflector between crystal elements should be well optimized. The optical design of reflectors was optimized using DETECT2000, a Monte Carlo code for light photon transport. A laser-cut reflector set was developed using the Enhanced Specular Reflector (ESR, 3M Co.) mirror-film with a high reflectance of 98% and a thickness of 0.064 mm. All 81 crystal elements of detector module were identified. Our result demonstrates that the C-shaped PET system is under development and we present the first reconstructed image.

  4. Monolithically Peltier-cooled laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Hava, S.; Hunsperger, R.G.; Sequeira, H.B.

    1984-04-01

    A new method of cooling a GaAs/GaAlAs laser in an optical integrated circuit or on a discrete chip, by adding an integral thermoelectric (Peltier) cooling and heat spreading device to the laser, is presented. This cooling both reduces and stabilizes the laser junction temperature to minimize such deleterious effects as wavelength drift due to heating. A unified description of the electrical and thermal properties of a monolithic semiconductor mesa structure is given. Here it is shown that an improvement in thermal characteristics is obtained by depositing a relatively thick metallic layer, and by using this layer as a part of an active Peltier structure. Experimental results reveal a 14-percent increase in emitted power (external quantum efficiency) due to passive heat spreading and a further 8-percent if its Peltier cooler is operated. Fabrication techniques used to obtain devices exhibiting the above performance characteristics are given. 21 references.

  5. LSST primary/tertiary monolithic mirror

    Science.gov (United States)

    Sebag, J.; Gressler, W.; Liang, M.; Neill, D.; Araujo-Hauck, C.; Andrew, J.; Angeli, G.; Cho, M.; Claver, C.; Daruich, F.; Gessner, C.; Hileman, E.; Krabbendam, V.; Muller, G.; Poczulp, G.; Repp, R.; Wiecha, O.; Xin, B.; Kenagy, K.; Martin, H. M.; Tuell, M. T.; West, S. C.

    2016-08-01

    At the core of the Large Synoptic Survey Telescope (LSST) three-mirror optical design is the primary/tertiary (M1M3) mirror that combines these two large mirrors onto one monolithic substrate. The M1M3 mirror was spin cast and polished at the Steward Observatory Mirror Lab at The University of Arizona (formerly SOML, now the Richard F. Caris Mirror Lab at the University of Arizona (RFCML)). Final acceptance of the mirror occurred during the year 2015 and the mirror is now in storage while the mirror cell assembly is being fabricated. The M1M3 mirror will be tested at RFCML after integration with its mirror cell before being shipped to Chile.

  6. A monolithic thin film electrochromic window

    Energy Technology Data Exchange (ETDEWEB)

    Goldner, R.B.; Arntz, F.O.; Berera, G.; Haas, T.E.; Wong, K.K. (Tufts Univ., Medford, MA (United States). Electro-Optics Technology Center); Wei, G. (Mobil Solar Energy Corp., Billerica, MA (United States)); Yu, P.C. (PPG Industries, Inc., Monroeville, PA (United States))

    1991-01-01

    Three closely related thin film solid state ionic devices that are potentially important for applications are: electrochromic smart windows, high energy density thin film rechargeable batteries, and thin film electrochemical sensors. Each usually has at least on mixed ion/electron conductor, an electron-blocking ion conductor, and an ion-blocking electron conductor, and many of the technical issues associated with thin film solid state ionics are common to all three devices. Since the electrochromic window has the added technical requirement of electrically-controlled optical modulation, (over the solar spectrum), and since research at the authors' institution has focused primarily on the window structure, this paper will address the electrochromic window, and particularly a monolithic variable reflectivity electrochromic window, as an illustrative example of some of the challenges and opportunities that are confronting the thin film solid state ionics community. 33 refs.

  7. A monolithic thin film electrochromic window

    Energy Technology Data Exchange (ETDEWEB)

    Goldner, R.B.; Arntz, F.O.; Berera, G.; Haas, T.E.; Wong, K.K. [Tufts Univ., Medford, MA (United States). Electro-Optics Technology Center; Wei, G. [Mobil Solar Energy Corp., Billerica, MA (United States); Yu, P.C. [PPG Industries, Inc., Monroeville, PA (United States)

    1991-12-31

    Three closely related thin film solid state ionic devices that are potentially important for applications are: electrochromic smart windows, high energy density thin film rechargeable batteries, and thin film electrochemical sensors. Each usually has at least on mixed ion/electron conductor, an electron-blocking ion conductor, and an ion-blocking electron conductor, and many of the technical issues associated with thin film solid state ionics are common to all three devices. Since the electrochromic window has the added technical requirement of electrically-controlled optical modulation, (over the solar spectrum), and since research at the authors` institution has focused primarily on the window structure, this paper will address the electrochromic window, and particularly a monolithic variable reflectivity electrochromic window, as an illustrative example of some of the challenges and opportunities that are confronting the thin film solid state ionics community. 33 refs.

  8. Machining distortion prediction of aerospace monolithic components

    Institute of Scientific and Technical Information of China (English)

    Yun-bo BI; Qun-lin CHENG; Hui-yue DONG; Ying-lin KE

    2009-01-01

    To predict the distortion of aerospace monolithic components.a model is established to simulate the numerical control (NC)milling process using 3D finite element method(FEM).In this model,the cutting layer is simplified firstly.Then,the models of cutting force and cutting temperature are established to gain the cutting loads,which are applied to the mesh model of the part.Finally,a prototype of machining simulation environment is developed to simulate the milling process of a spar.Key factors influencing the distortion,such as initial residual stress,cutting loads,fixture layout,cutting sequence,and tool path are considered all together.The total distortion of the spar is predicted and an experiment is conducted to validate the numerical results.It is found that the maximum discrepancy between the simulation results and experiment values is 19.0%

  9. Solid oxide fuel cell having monolithic core

    Science.gov (United States)

    Ackerman, J. P.; Young, J. E.

    1983-10-01

    A solid oxide fuel cell is described for electrochemically combining fuel and oxidant for generating galvanic output, wherein the cell core has an array of electrolyte and interconnect walls that are substantially devoid of any composite inert materials for support. The core is monolithic, where each electrolyte wall consists of thin layers of cathode and anode materials sandwiching a thin layer of electrolyte material. The electrolyte walls are arranged and backfolded between adjacent interconnect walls operable to define a plurality of core passageways alternately arranged where the inside faces have only the anode material or only the cathode material exposed. Each layer of the electrolyte and interconnect materials 0.002 to 0.01 cm thick; and each layer of the cathode and anode materials is 0.002 to 0.05 cm thick.

  10. Silver deposition on chemically treated carbon monolith

    Directory of Open Access Journals (Sweden)

    Jovanović Zoran M.

    2009-01-01

    Full Text Available Carbon monolith was treated with HNO3, KOH and H2O2. Effects of these treatments on the surface functional groups and on the amount of silver deposited on the CM surface were studied by temperature programmed desorption (TPD and atomic absorption spectrometry (AAS. As a result of chemical treatment there was an increase in the amount of surface oxygen complexes. The increase in the amount of silver deposit is proportional to the amount of surface groups that produce CO under decomposition. However, the high amount of CO groups, decomposing above 600°C, induces the smaller Ag crystallite size. Therefore, the high temperature CO evolving oxides are, most likely, the initial centers for Ag deposition.

  11. Crystallinity and stoichiometry of nano-structured sol-gel-derived BaTiO{sub 3} monolithic gels

    Energy Technology Data Exchange (ETDEWEB)

    Shimooka, Hirokazu [Kyushu Inst. of Tech., Kitakyushu, Fukuoka (Japan). Dept. of Applied Chemistry; Kuwabara, Makoto [Univ. of Tokyo (Japan). Dept. of Materials Science

    1996-11-01

    The crystallization behavior and stoichiometric changes of barium titanium alkoxide-derived monolithic gels prepared by the sol-gel process using a high-concentration Ba,Ti precursor solution (0.8 mol/L) were investigated during aging at room temperature. Crystallization of the gels (which were amorphous, per X-ray diffraction analysis immediately after gelation) into the BaTiO{sub 3} perovskite phase increased during aging and was associated with significant shrinkage of the gels. Crystallization reached a value of {approximately}82% by the final stage of shrinkage, assuming the degree of crystallization of a gel treated at 600 C to be 100%. The stoichiometry of the gels (Ba/Ti molar ratio) also changed considerably during aging, as estimated by the concentrations of Ba and Ti that remained in the expelled liquid resulting from syneresis at any time during the aging process. Deviation in the Ba/Ti ratio of the precursor solution ranged from 0.015 at the initial stage of shrinkage to 0.003 at the final stage, a value determined by inductively coupled plasma atomic emission spectroscopy. The present study demonstrates the great advantage of using high-concentration precursor solutions of barium titanium alkoxides, rather than low-concentration solutions, to obtain BaTiO{sub 3} gel monoliths with high density and crystallinity and little stoichiometric deviation, by sol-gel processing at room temperature.

  12. Fundamentals of PET and PET/CT imaging.

    Science.gov (United States)

    Basu, Sandip; Kwee, Thomas C; Surti, Suleman; Akin, Esma A; Yoo, Don; Alavi, Abass

    2011-06-01

    In this review, the fundamental principles of fluorodeoxyglucose (FDG) positron emission tomography (PET) and FDG PET/computed tomography (CT) imaging have been described. The basic physics of PET instrumentation, radiotracer chemistry, and the artifacts, as well as normal physiological or benign pathological variants, have been described and presented to the readers in a lucid manner to enable them an easy grasp of the fundamentals of the subject. Finally, we have outlined the current developments in quantitative PET imaging, including dual time point and delayed PET imaging, time-of-flight technology in PET imaging and partial volume correction, and global disease assessment with their potential of being incorporated into the assessment of benign and malignant disorders.

  13. Monolithic Rare Earth Doped PTR Glass Laser Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The main goal of the project is to demonstrate the feasibility of a monolithic solid state laser on the basis of PTR glass co-doped with luminescent rare earth ions....

  14. Plant oil-based shape memory polymer using acrylic monolith

    Directory of Open Access Journals (Sweden)

    T. Tsujimoto

    2015-09-01

    Full Text Available This article deals with the synthesis of a plant oil-based material using acrylic monolith. An acrylic monolith bearing oxirane groups was prepared via simple technique that involved the dissolution of poly(glycidyl methacrylate-comethyl methacrylate (PGMA in ethanolic – aqueous solution by heating and subsequent cooling. The PGMA monolith had topologically porous structure, which was attributed to the phase separation of the polymer solution. The PGMA monolith was impregnated by epoxidized soybean oil (ESO containing thermally-latent catalyst, and the subsequent curing produced a crosslinked material with relatively good transparency. The Young’s modulus and the tensile strength of polyESO/PGMA increased compared with the ESO homopolymer. The strain at break of polyESO/PGMA was larger than that of the ESO homopolymer and crosslinked PGMA. Furthermore, polyESO/PGMA exhibited good shape memory-recovery behavior.

  15. Application of monolithic chromatographic supports in virus research.

    Science.gov (United States)

    Krajacic, Mladen; Ravnikar, Maja; Štrancar, Aleš; Gutiérrez-Aguirre, Ion

    2017-05-12

    Key properties of monolithic chromatographic supports, make them suitable for separation and/or concentration of large biomolecules, especially virus particles and viral genomes. One by one, the studies that have been completed so far, contributed to the knowledge that monolith chromatography has hardly any limitation to be applied in virus research. Viruses of different sizes, possessing icosahedral structure and symmetrical morphology, as well as rod-shaped or filamentous viruses with helical structure, even enveloped ones, all of them could be successfully managed by means of monolith chromatography. Same is true for viral genomes, primarily when being distinct from other nucleic acid forms present in a host cell. This review is exclusively focused on viruses. It describes the application of monolith chromatography to different problematics within the virus research field. The reviewed achievements offer new possibilities and trigger new aspects in virology. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Monolithic Perovskite Silicon Tandem Solar Cells with Advanced Optics

    Energy Technology Data Exchange (ETDEWEB)

    Goldschmidt, Jan C.; Bett, Alexander J.; Bivour, Martin; Blasi, Benedikt; Eisenlohr, Johannes; Kohlstadt, Markus; Lee, Seunghun; Mastroianni, Simone; Mundt, Laura; Mundus, Markus; Ndione, Paul; Reichel, Christian; Schubert, Martin; Schulze, Patricia S.; Tucher, Nico; Veit, Clemens; Veurman, Welmoed; Wienands, Karl; Winkler, Kristina; Wurfel, Uli; Glunz, Stefan W.; Hermle, Martin

    2016-11-14

    For high efficiency monolithic perovskite silicon tandem solar cells, we develop low-temperature processes for the perovskite top cell, rear-side light trapping, optimized perovskite growth, transparent contacts and adapted characterization methods.

  17. Effect of accelerated aging on translucency of monolithic zirconia

    Directory of Open Access Journals (Sweden)

    O. Abdelbary

    2016-12-01

    Conclusion: Thickness of zirconia has significant effect on translucency. Aging has significant effect on thinner sections of zirconia. More research is required on zirconia towards making the material more translucent for its potential use as esthetic monolithic restoration.

  18. Monolithic CMOS pixel detector for international linear collider vertex detection

    Indian Academy of Sciences (India)

    J E Brau; O Igonkina; N Sinew; D Strom; C Baltay; W Emmet; H Neal; D Rabinowitz

    2007-12-01

    A monolithic CMS pixel detector is under development for an ILC experiment. This chronopixel array provides a time stamp resolution of one bunch crossing, a critical feature for background suppression. The status of this effort is summarized.

  19. Design and performance of HEAD PENN-PET scanner

    Energy Technology Data Exchange (ETDEWEB)

    Freifelder, R.; Karp, J.S. (Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Radiology); Geagan, M.; Muehllehner, G. (UGM Medical Systems Inc., Philadelphia, PA (United States))

    1994-08-01

    A new PET scanner for brain imaging (and animals) has been designed with very high sensitivity and spatial resolution. The design is an evolution of the PENN-PET scanner, which uses large position-sensitive NaI(Tl) detectors, with Anger-type positioning logic, and which allows 3-D volume imaging, without septa. The new design is built with a single annular crystal coupled to 180 photomultiplier tubes, and uses local triggering electronics to subdivide the detector into small zones and to determine coincident events within the detector. The axial acceptance angle of [+-] 27 deg, with a field-of-view of 25.6 cm, is larger than any currently operating PET scanner. Performance measurements are presented.

  20. High-grade lymphoma of the bladder visualized on PET.

    Science.gov (United States)

    Mantzarides, M; Papathanassiou, D; Bonardel, G; Soret, M; Gontier, E; Foehrenbach, H

    2005-07-01

    F-18 FDG PET is used for the staging of many cancers. One of its limits is the analysis of the pelvis and the urinary tract because of physiological radiotracer excretion. We report a rare case of an 82-year-old woman in whom intravenous administration of diuretics (furosemide) allowed the identification of a primary diffuse large B-cell lymphoma of the bladder wall. This pharmaceutical increases urine flow and, therefore, reduces the concentration of radiotracer in the urinary tract, improving the visualization of pelvic or urinary tumors. Furosemide administration is an easy, safe, and noninvasive method, even in case of renal insufficiency. Newer PET cameras with high-performance crystals allow rapid acquisitions and improve the tolerance of an examination with diuretic injection. The 3-dimensional reconstruction of images in new PET cameras reduces the occurrence of hyperactive bladder artifacts. The present case illustrates the advantages of furosemide in a rare pathologic entity.

  1. The AX-PET demonstrator-Design, construction and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Beltrame, P. [CERN, PH Department, CH-1211 Geneva (Switzerland); Bolle, E. [University of Oslo, NO-0317 Oslo (Norway); Braem, A. [CERN, PH Department, CH-1211 Geneva (Switzerland); Casella, C., E-mail: Chiara.Casella@cern.ch [Institute for Particle Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Chesi, E. [Ohio State University, Columbus, Ohio 43210 (United States); Clinthorne, N. [University of Michigan, Ann Arbor, MI 48109 (United States); De Leo, R. [INFN, Sezione di Bari, I-70122 Bari (Italy); Dissertori, G.; Djambazov, L. [Institute for Particle Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Fanti, V.; Heller, M.; Joram, C. [CERN, PH Department, CH-1211 Geneva (Switzerland); Kagan, H. [Ohio State University, Columbus, Ohio 43210 (United States); Lustermann, W. [Institute for Particle Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Meddi, F. [University of Rome ' La Sapienza' , I-00185 Rome (Italy); Nappi, E. [INFN, Sezione di Bari, I-70122 Bari (Italy); Nessi-Tedaldi, F. [Institute for Particle Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Oliver, J.F. [IFIC (Universidad de Valencia/CSIC), E-46071 Valencia (Spain); Pauss, F. [Institute for Particle Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Rafecas, M. [IFIC (Universidad de Valencia/CSIC), E-46071 Valencia (Spain); and others

    2011-10-21

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

  2. High-Resolution PET Detector. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Karp, Joel

    2014-03-26

    The objective of this project was to develop an understanding of the limits of performance for a high resolution PET detector using an approach based on continuous scintillation crystals rather than pixelated crystals. The overall goal was to design a high-resolution detector, which requires both high spatial resolution and high sensitivity for 511 keV gammas. Continuous scintillation detectors (Anger cameras) have been used extensively for both single-photon and PET scanners, however, these instruments were based on NaI(Tl) scintillators using relatively large, individual photo-multipliers. In this project we investigated the potential of this type of detector technology to achieve higher spatial resolution through the use of improved scintillator materials and photo-sensors, and modification of the detector surface to optimize the light response function.We achieved an average spatial resolution of 3-mm for a 25-mm thick, LYSO continuous detector using a maximum likelihood position algorithm and shallow slots cut into the entrance surface.

  3. Performance characteristics between monolithic and microservice-based systems

    OpenAIRE

    Flygare, Robin; Holmqvist, Anthon

    2017-01-01

    A new promising technology to face the problem of scalability and availability is the microservice architecture. The problem with this architecture is that there is no significant study that clearly proves the performance differences compared to the monolithic architecture. Our thesis aims to provide a more conclusive answer of how the microservice architecture differs performance wise compared to the monolithic architecture. In this study, we conducted several experiments on a self-developed...

  4. Sol-Gel Synthesis of Non-Silica Monolithic Materials

    Directory of Open Access Journals (Sweden)

    Bartłomiej Gaweł

    2010-04-01

    Full Text Available Monolithic materials have become very popular because of various applications, especially within chromatography and catalysis. Large surface areas and multimodal porosities are great advantages for these applications. New sol-gel preparation methods utilizing phase separation or nanocasting have opened the possibility for preparing materials of other oxides than silica. In this review, we present different synthesis methods for inorganic, non-silica monolithic materials. Some examples of application of the materials are also included.

  5. Reliability Analysis and Optimal Design of Monolithic Vertical Wall Breakwaters

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Burcharth, Hans F.; Christiani, E.

    1994-01-01

    Reliability analysis and reliability-based design of monolithic vertical wall breakwaters are considered. Probabilistic models of the most important failure modes, sliding failure, failure of the foundation and overturning failure are described . Relevant design variables are identified and relia......Reliability analysis and reliability-based design of monolithic vertical wall breakwaters are considered. Probabilistic models of the most important failure modes, sliding failure, failure of the foundation and overturning failure are described . Relevant design variables are identified...

  6. Extended Leach Testing of Simulated LAW Cast Stone Monoliths

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R. Jeffrey [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Westsik, Joseph H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Williams, Benjamin D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jung, H. B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Guohui [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-07-09

    This report describes the results from long-term laboratory leach tests performed at Pacific Northwest National Laboratory (PNNL) for Washington River Protection Solutions (WRPS) to evaluate the release of key constituents from monoliths of Cast Stone prepared with four simulated low-activity waste (LAW) liquid waste streams. Specific objectives of the Cast Stone long-term leach tests described in this report focused on four activities: 1. Extending the leaching times for selected ongoing EPA-1315 tests on monoliths made with LAW simulants beyond the conventional 63-day time period up to 609 days reported herein (with some tests continuing that will be documented later) in an effort to evaluate long-term leaching properties of Cast Stone to support future performance assessment activities. 2. Starting new EPA-1315 leach tests on archived Cast Stone monoliths made with four LAW simulants using two leachants (deionized water [DIW] and simulated Hanford Integrated Disposal Facility (IDF) Site vadose zone pore water [VZP]). 3. Evaluating the impacts of varying the iodide loading (starting iodide concentrations) in one LAW simulant (7.8 M Na Hanford Tank Waste Operations Simulator (HTWOS) Average) by manufacturing new Cast Stone monoliths and repeating the EPA-1315 leach tests using DIW and the VZP leachants. 4. Evaluating the impacts of using a non-pertechnetate form of Tc that is present in some Hanford tanks. In this activity one LAW simulant (7.8 M Na HTWOS Average) was spiked with a Tc(I)-tricarbonyl gluconate species and then solidified into Cast Stone monoliths. Cured monoliths were leached using the EPA-1315 leach protocol with DIW and VZP. The leach results for the Tc-Gluconate Cast Stone monoliths were compared to Cast Stone monoliths pertechnetate.

  7. Mechanically stable, hierarchically porous Cu3(btc)2 (HKUST-1) monoliths via direct conversion of copper(II) hydroxide-based monoliths.

    Science.gov (United States)

    Moitra, Nirmalya; Fukumoto, Shotaro; Reboul, Julien; Sumida, Kenji; Zhu, Yang; Nakanishi, Kazuki; Furukawa, Shuhei; Kitagawa, Susumu; Kanamori, Kazuyoshi

    2015-02-28

    The synthesis of highly crystalline macro-meso-microporous monolithic Cu3(btc)2 (HKUST-1; btc(3-) = benzene-1,3,5-tricarboxylate) is demonstrated by direct conversion of Cu(OH)2-based monoliths while preserving the characteristic macroporous structure. The high mechanical strength of the monoliths is promising for possible applications to continuous flow reactors.

  8. PET/PCTG比例对共混材料热性能影响%Influence of PET/PCTG Ratio on Thermal Properties of Blends

    Institute of Scientific and Technical Information of China (English)

    李敏雯; 张钦发; 李夏君; 张义珂

    2016-01-01

    聚对苯二甲酸乙二醇/环已烷二甲醇酯(PCTG)由于其具有较高的玻璃化温度且与PET具有结构上的相似性,PET与PCTG共混有助提高材料的耐热性能.研究PET与PCTG共混材料的热性能可为共混材料成型加工提供理论基础.文章对不同比例PET/PCTG共混材料进行升温和降温差示扫描量热分析(DSC),研究了不同比例PET/PCTG共混材料的冷、热结晶性能.研究结果表明:不同比例的PET/PCTG共混材料的冷、热结晶峰值温度不相同,当PET/PCTG比例为7:3时,其冷结晶峰值温度最低,结晶熔融峰值温度和热结晶峰值温度最高.%Poly((ethylene-co-cyclohexane1,4-dimethanol) terephthalate (PCTG) was similar in chemical structure and higher glass transition temperature compared with PET.Heat durability and impact strength of PET/PCTG bottles could be improved by blending with PCTG.Study on thermal properties of PET/PCTG blends were the basis of molding and processing conditions for PET/PCTG blends.The crystallinity of various PET/PCTG blends had been researched by analyzed using differential scanning calorimetry (DSC),results showed that crystallization temperature and melting temperature of blends with various PET/PCTG ratio were different,cold peak crystallization temperature of PET/PCTG blends were lowest,and heat peak crystallization temperature and peak melting temperature were highest when PET/PCTG was 7:3.

  9. Are Pets Good For Us?

    Institute of Scientific and Technical Information of China (English)

    邢连香

    2006-01-01

    A pet animal keeps us feel happy.Pets can staywith us when we are left by ourselves,and pets in-vite us to love and be loved.Often a cat or dog cankeep us easy at time when human words don’t help.Pets also keep us get close to the more natural animalworld.Learning to care for a pet helps a child to growup into a loving man or woman who feels responsible(有责任的) towards those dependent (依靠) on him.A pet dog can make us believe in others for we cansee faithfulness (忠诚) in the dog.In fact,we keeppets not only fo...

  10. Ingredients: where pet food starts.

    Science.gov (United States)

    Thompson, Angele

    2008-08-01

    Every clinician is asked "What should I feed my pet?" Understanding the ingredients in pet food is an important part of making the best recommendation. Pet food can be as simple as one ingredient or as complicated as containing more than 60 ingredients. Pet food and its ingredients are regulated by the Food and Drug Administration and state feed officials. Part of that regulation is the review and definition of ingredients. Existing ingredients change and new ingredients become available so the need for ingredient definitions grows. Ingredients for product formulations are chosen based on their nutrient content, digestibility, palatability, functionality, availability, and cost. As an example, a typical, nutritionally complete dry dog food with 42 ingredients is examined and the ingredients are discussed here. Safe, healthy pet food starts with safe ingredients sourced from well-monitored suppliers. The ultimate goal of both veterinarians and pet food manufacturers is the same--long healthy lives for dogs and cats.

  11. Monoliths: A Review of the Basics, Preparation Methods and Their Relevance to Oxidation

    Directory of Open Access Journals (Sweden)

    Sandeeran Govender

    2017-02-01

    Full Text Available Considerable research has been conducted on monolithic catalysts for various applications. Strategies toward coating monoliths are of equal interest and importance. In this paper, the preparation of monoliths and monolithic catalysts have been summarized. More specifically, a brief explanation for the manufacturing of ceramic and metallic monoliths has been provided. Also, different methods for coating γ-alumina, as a secondary support, are included. Techniques used to deposit metal-based species, zeolites and carbon onto monoliths are discussed. Furthermore, monoliths extruded with metal oxides, zeolites and carbon are described. The main foci are on the reasoning and understanding behind the preparation of monolithic catalysts. Ideas and concerns are also contributed to encourage better approaches when designing these catalysts. More importantly, the relevance of monolithic structures to reactions, such as the selective oxidation of alkanes, catalytic combustion for power generation and the preferential oxidation of carbon monoxide, has been described.

  12. 固相挤出回收PET结晶性能和降解程度的研究%Study on Crystallization and Degradation of Recycled PET Treated by Solid-state Extrusion

    Institute of Scientific and Technical Information of China (English)

    唐琦琦; 付强; 杨斌; 李润明; 周持兴

    2005-01-01

    提出一种全新的固相挤出加工方法,即在低温下用双螺杆挤出机挤出加工回收聚对苯二甲酸乙二醇酯(PET).用WAXD和DSC分别考察PET的结晶形态和结晶性能,通过考察熔体流动速率和特性黏度的变化,评价回收PET树脂的降解程度.研究发现,与传统的熔融挤出法相比,经过固相挤出造粒的回收PET结晶更完善,结晶度提高了10%,晶粒大小分布更窄,而且降解程度有效地减小.

  13. Infections That Pets Carry (For Parents)

    Science.gov (United States)

    ... Your 1- to 2-Year-Old Infections That Pets Carry KidsHealth > For Parents > Infections That Pets Carry ... how to protect your family from infections. How Pets Spread Infections Like people, all animals carry germs . ...

  14. Pet overpopulation: An economic analysis

    OpenAIRE

    Coate, Stephen; Knight, Brian

    2009-01-01

    This paper considers the problem of pet overpopulation. It develops a tractable dynamic model whose positive predictions square well with key features of the current U.S. market for pets. The model is used to understand, from a welfare economic perspective, the sense in which there is \\overpopulation" of pets and the underlying causes of the problem. The paper also employs the model to consider what policies might be implemented to deal with the problem. A calibrated example is developed to i...

  15. PET radiopharmaceuticals for neuroreceptor imaging

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Routine clinical PET radiopharmaceuticals for the noninvasive imaging of brain receptors, transporters,and enzymes are commonly labeled with positron emitting nuclides such as carbon-11 or fluorine-18. Certain minimal conditions need to be fulfilled for these PET ligands to be used as imaging agents in vivo. Some of these prerequisites are discussed and examples of the most useful clinical PET radiopharmaceuticals that have found application in the central nervous system are reviewed.

  16. PET and Recycling

    Directory of Open Access Journals (Sweden)

    Funda Sevencan

    2007-08-01

    Full Text Available This review aims to clarify the need of decreasing the environmental effects caused by human and draw attention to the increasing environmental effects of plastics wastes. Plastics consist of organic molecules with high density molecules or polymers. Main resources of plastics are the residue of oil rafineries. Several advantages of plastics, have increased the usage continuously. Polyethylene Terephthalate (PET is the most commonly used plastics. PET is used to protect food, drinking water, fruit juice, alcoholic beverage, and food packing films. By the increasing interest on the environmental effects of plastic wastes, concerns on the recyclable packing materials also grew up. Also the daily use of recyclable containers consisting PET have increased. There are five steps for recycling of plastics. These steps are; using large amounts of plastics, collecting them in a big center, classifying and sorting the plastics, reproducing the polymers and obtaining new products with melted plastics. Providing a healthy recycling of plastics, the consumers should have knowledge and responsibility. The consumer should know what he/she has to do before putting the plastics in the recycling containers. Recycling containers and bags should be placed near the sources of plastic wastes. Consequently, the plastic wastes and environmental problems they cause will be on the agenda in future. [TAF Prev Med Bull. 2007; 6(4: 307-312

  17. Polymethacrylate monolithic and hybrid particle-monolithic columns for reversed-phase and hydrophilic interaction capillary liquid chromatography.

    Science.gov (United States)

    Jandera, Pavel; Urban, Jirí; Skeríková, Veronika; Langmaier, Pavel; Kubícková, Romana; Planeta, Josef

    2010-01-01

    We prepared hybrid particle-monolithic polymethacrylate columns for micro-HPLC by in situ polymerization in fused silica capillaries pre-packed with 3-5microm C(18) and aminopropyl silica bonded particles, using polymerization mixtures based on laurylmethacrylate-ethylene dimethacrylate (co)polymers for the reversed-phase (RP) mode and [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl) zwitterionic (co)polymers for the hydrophilic interaction (HILIC) mode. The hybrid particle-monolithic columns showed reduced porosity and hold-up volumes, approximately 2-2.5 times lower in comparison to the pure monolithic columns prepared in the whole volume of empty capillaries. The elution volumes of sample compounds are also generally lower in comparison to packed or pure monolithic columns. The efficiency and permeability of the hybrid columns are intermediate in between the properties of the reference pure monolithic and particle-packed columns. The chemistries of the embedded solid particles and of the interparticle monolithic moiety in the hybrid capillary columns contribute to the retention to various degrees, affecting the selectivity of separation. Some hybrid columns provided improved separations of proteins in comparison to the reference particle-packed columns in the reversed-phase mode. Zwitterionic hybrid particle-monolithic columns show dual mode retention HILIC/RP behaviour depending on the composition of the mobile phase and allow separations of polar compounds such as phenolic acids in the HILIC mode at lower concentrations of acetonitrile and, often in shorter analysis time in comparison to particle-packed and full-volume monolithic columns.

  18. A dedicated high resolution PET imager for plant sciences

    CERN Document Server

    Wang, Qiang; Li, Ke; Wen, Jie; Komarov, Sergey; O'Sullivan, Joseph A; Tai, Yuan-Chuan

    2014-01-01

    PET provides in vivo molecular and functional imaging capability that is crucial to studying the interaction of plant with changing environment at the whole-plant level. We have developed a dedicated plant PET imager that features high spatial resolution, housed in a fully controlled environment provided by a plant growth chamber (PGC). The system currently contains two types of detector modules: 84 microPET R4 block detectors with 2.2 mm crystals to provide a large detecting area; and 32 Inveon block detectors with 1.5 mm crystals to provide higher spatial resolution. Outputs of the four microPET block detectors in a modular housing are concatenated by a custom printed circuit board to match the output characteristics of an Inveon detector. All the detectors are read out by QuickSilver electronics. The detector modules are configured to full rings with a 15 cm diameter trans-axial field of view (FOV) for dynamic tomographic imaging of small plants. Potentially, the Inveon detectors can be reconfigured to qua...

  19. Performance evaluation of the microPET P4: a PET system dedicated to animal imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tai, Y.C.; Chatziioannou, A.; Cherry, S.R. [Crump Institute for Molecular Imaging, UCLA School of Medicine, Los Angeles, CA (United States); Siegel, S.; Goble, R.N.; Nutt, R.E. [Concorde Microsystems, Inc, Knoxville, TN (United States); Young, J. [CTI, Inc, Knoxville, TN (United States); Newport, D. [Electrical and Computer Engineering, University of Tennessee, Knoxville, TN (United States)

    2001-07-01

    The microPET Primate 4-ring system (P4) is an animal PET tomograph with a 7.8 cm axial extent, a 19 cm diameter transaxial field of view (FOV) and a 22 cm animal port. The system is composed of 168 detector modules, each with an 8x8 array of 2.2x2.2x10 mm{sup 3} lutetium oxyorthosilicate crystals, arranged as 32 crystal rings 26 cm in diameter. The detector crystals are coupled to a Hamamatsu R5900-C8 PS-PMT via a 10 cm long optical fibre bundle. The detectors have a timing resolution of 3.2 ns, an average energy resolution of 26%, and an average intrinsic spatial resolution of 1.75 mm. The system operates in 3D mode without inter-plane septa, acquiring data in list mode. The reconstructed image spatial resolution ranges from 1.8 mm at the centre to 3 mm at 4 cm radial offset. The tomograph has a peak system sensitivity of 2.25% at the centre of the FOV with a 250-750 keV energy window. The noise equivalent count rate peaks at 100-290 kcps for representative object sizes. Images from two phantoms and three different types of laboratory animal demonstrate the advantage of the P4 system over the original prototype microPET, including its threefold improvement in sensitivity and a large axial FOV sufficient to image an entire mouse in a single bed position. (author)

  20. Performance evaluation of the microPET P4: a PET system dedicated to animal imaging

    Science.gov (United States)

    Tai, Y. C.; Chatziioannou, A.; Siegel, S.; Young, J.; Newport, D.; Goble, R. N.; Nutt, R. E.; Cherry, S. R.

    2001-07-01

    The microPET Primate 4-ring system (P4) is an animal PET tomograph with a 7.8 cm axial extent, a 19 cm diameter transaxial field of view (FOV) and a 22 cm animal port. The system is composed of 168 detector modules, each with an 8×8 array of 2.2×2.2×10 mm3 lutetium oxyorthosilicate crystals, arranged as 32 crystal rings 26 cm in diameter. The detector crystals are coupled to a Hamamatsu R5900-C8 PS-PMT via a 10 cm long optical fibre bundle. The detectors have a timing resolution of 3.2 ns, an average energy resolution of 26%, and an average intrinsic spatial resolution of 1.75 mm. The system operates in 3D mode without inter-plane septa, acquiring data in list mode. The reconstructed image spatial resolution ranges from 1.8 mm at the centre to 3 mm at 4 cm radial offset. The tomograph has a peak system sensitivity of 2.25% at the centre of the FOV with a 250-750 keV energy window. The noise equivalent count rate peaks at 100-290 kcps for representative object sizes. Images from two phantoms and three different types of laboratory animal demonstrate the advantage of the P4 system over the original prototype microPET, including its threefold improvement in sensitivity and a large axial FOV sufficient to image an entire mouse in a single bed position.

  1. Extended suicide with a pet.

    Science.gov (United States)

    Cooke, Brian K

    2013-01-01

    The combination of the killing of a pet and a suicide is a perplexing scenario that is largely unexplored in the literature. Many forensic psychiatrists and psychologists may be unaccustomed to considering the significance of the killing of a pet. The subject is important, however, because many people regard their pets as members of their family. A case is presented of a woman who killed her pet dog and herself by carbon monoxide poisoning. The purpose of this article is to provide an initial exploration of the topic of extended suicide with a pet. Forensic mental health evaluations may have a role in understanding the etiology of this event and in opining as to the culpability of individuals who attempt to or successfully kill a pet and then commit suicide. Because the scientific literature is lacking, there is a need to understand this act from a variety of perspectives. First, a social and anthropological perspective will be presented that summarizes the history of the practice of killing of one's pet, with a focus on the ancient Egyptians. A clinical context will examine what relationship animals have to mental illness. A vast body of existing scientific data showing the relevance of human attachment to pets suggests that conclusions from the phenomena of homicide-suicide and filicide-suicide are applicable to extended suicide with a pet. Finally, recommendations will be proposed for both clinical and forensic psychiatrists faced with similar cases.

  2. Respiratory gating in cardiac PET

    DEFF Research Database (Denmark)

    Lassen, Martin Lyngby; Rasmussen, Thomas; Christensen, Thomas E

    2017-01-01

    BACKGROUND: Respiratory motion due to breathing during cardiac positron emission tomography (PET) results in spatial blurring and erroneous tracer quantification. Respiratory gating might represent a solution by dividing the PET coincidence dataset into smaller respiratory phase subsets. The aim...... stress (82)RB-PET. Respiratory rates and depths were measured by a respiratory gating system in addition to registering actual respiratory rates. Patients undergoing adenosine stress showed a decrease in measured respiratory rate from initial to later scan phase measurements [12.4 (±5.7) vs 5.6 (±4.......7) min(-1), P PET...

  3. Biasable, Balanced, Fundamental Submillimeter Monolithic Membrane Mixer

    Science.gov (United States)

    Siegel, Peter; Schlecht, Erich; Mehdi, Imran; Gill, John; Velebir, James; Tsang, Raymond; Dengler, Robert; Lin, Robert

    2010-01-01

    This device is a biasable, submillimeter-wave, balanced mixer fabricated using JPL s monolithic membrane process a simplified version of planar membrane technology. The primary target application is instrumentation used for analysis of atmospheric constituents, pressure, temperature, winds, and other physical and chemical properties of the atmospheres of planets and comets. Other applications include high-sensitivity gas detection and analysis. This innovation uses a balanced configuration of two diodes allowing the radio frequency (RF) signal and local oscillator (LO) inputs to be separated. This removes the need for external diplexers that are inherently narrowband, bulky, and require mechanical tuning to change frequency. Additionally, this mixer uses DC bias-ability to improve its performance and versatility. In order to solve problems relating to circuit size, the GaAs membrane process was created. As much of the circuitry as possible is fabricated on-chip, making the circuit monolithic. The remainder of the circuitry is precision-machined into a waveguide block that holds the GaAs circuit. The most critical alignments are performed using micron-scale semiconductor technology, enabling wide bandwidth and high operating frequencies. The balanced mixer gets superior performance with less than 2 mW of LO power. This can be provided by a simple two-stage multiplier chain following an amplifier at around 90 GHz. Further, the diodes are arranged so that they can be biased. Biasing pushes the diodes closer to their switching voltage, so that less LO power is required to switch the diodes on and off. In the photo, the diodes are at the right end of the circuit. The LO comes from the waveguide at the right into a reduced-height section containing the diodes. Because the diodes are in series to the LO signal, they are both turned on and off simultaneously once per LO cycle. Conversely, the RF signal is picked up from the RF waveguide by the probe at the left, and flows

  4. Integrated self-aligned tips for dispersion tuning in a photonic crystal micro-cavity

    NARCIS (Netherlands)

    Chakkalakkal Abdulla, S.M.; Kauppinen, L.J.; de Ridder, R.M.; Krijnen, Gijsbertus J.M.

    2011-01-01

    A micro-bimorph cantilever is monolithically integrated with a photonic crystal micro-cavity based device, using surface micro-machining techniques. The integrated cantilever is equipped with self-aligned dielectric tips with respect to the holes of the photonic crystal and on electrostatic

  5. Localisation of gamma-ray interaction points in thick monolithic CeBr3 and LaBr3:Ce scintillators

    Science.gov (United States)

    Ulyanov, Alexei; Morris, Oran; Roberts, Oliver J.; Tobin, Isaac; Hanlon, Lorraine; McBreen, Sheila; Murphy, David; Nelms, Nick; Shortt, Brian

    2017-02-01

    Localisation of gamma-ray interaction points in monolithic scintillator crystals can simplify the design and improve the performance of a future Compton telescope for gamma-ray astronomy. In this paper we compare the position resolution of three monolithic scintillators: a 28×28×20 mm3 (length×breadth × thickness) LaBr3:Ce crystal, a 25×25×20 mm3 CeBr3 crystal and a 25×25×10 mm3 CeBr3 crystal. Each crystal was encapsulated and coupled to an array of 4×4 silicon photomultipliers through an optical window. The measurements were conducted using 81 keV and 356 keV gamma-rays from a collimated 133Ba source. The 3D position reconstruction of interaction points was performed using artificial neural networks trained with experimental data. Although the position resolution was significantly better for the thinner crystal, the 20 mm thick CeBr3 crystal showed an acceptable resolution of about 5.4 mm FWHM for the x and y coordinates, and 7.8 mm FWHM for the z-coordinate (crystal depth) at 356 keV. These values were obtained from the full position scans of the crystal sides. The position resolution of the LaBr3:Ce crystal was found to be considerably worse, presumably due to the highly diffusive optical interface between the crystal and the optical window of the enclosure. The energy resolution (FWHM) measured for 662 keV gamma-rays was 4.0% for LaBr3:Ce and 5.5% for CeBr3. The same crystals equipped with a PMT (Hamamatsu R6322-100) gave an energy resolution of 3.0% and 4.7%, respectively.

  6. EFFECT OF INTERFACIAL ADHESION ON CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLY (ETHYLENE TEREPHTHALATE)/GLASS BEAD COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    OU Yuchun; YU Zhongzhen; ZHU Jin; LI Ge; ZHU Shanguang

    1996-01-01

    The interfacial adhesion between poly (ethylene terephthalate) (PET) and glass bead was investigated by scanning electron microscope and parallel-plate rheometer. Effect of interfacial adhesion on the crystallization and mechanical properties of PET/glass bead composites was also studied by differential scanning calorimeter and mechanical testers.The results obtained indicate that the glass bead has a heterogeneous nucleation effect on the PET crystallization. Although better interfacial adhesion is advantageous to the increase of the tensile strength of the composite, yet it is unfavorable to the crystallization of PET. It should be pointed out that the crystallization rate of filled PET is always higher than that of pure PET, regardless of the state of interfacial adhesion.

  7. Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

    Science.gov (United States)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

    2015-04-01

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

  8. Monolithically Integrated Microelectromechanical Systems for On-Chip Strain Engineering of Quantum Dots.

    Science.gov (United States)

    Zhang, Yang; Chen, Yan; Mietschke, Michael; Zhang, Long; Yuan, Feifei; Abel, Stefan; Hühne, Ruben; Nielsch, Kornelius; Fompeyrine, Jean; Ding, Fei; Schmidt, Oliver G

    2016-09-14

    Elastic strain fields based on single crystal piezoelectric elements represent an effective way for engineering the quantum dot (QD) emission with unrivaled precision and technological relevance. However, pioneering researches in this direction were mainly based on bulk piezoelectric substrates, which prevent the development of chip-scale devices. Here, we present a monolithically integrated Microelectromechanical systems (MEMS) device with great potential for on-chip quantum photonic applications. High-quality epitaxial PMN-PT thin films have been grown on SrTiO3 buffered Si and show excellent piezoelectric responses. Dense arrays of MEMS with small footprints are then fabricated based on these films, forming an on-chip strain tuning platform. After transferring the QD-containing nanomembranes onto these MEMS, the nonclassical emissions (e.g., single photons) from single QDs can be engineered by the strain fields. We envision that the strain tunable QD sources on the individually addressable and monolithically integrated MEMS pave the way toward complex quantum photonic applications on chip.

  9. Preliminary results of a prototype C-shaped PET designed for an in-beam PET system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun-Il [Department of Radiation Convergence Engineering, Yonsei University, Wonju 220-710 (Korea, Republic of); Chung, Yong Hyun, E-mail: ychung@yonsei.ac.kr [Department of Radiation Convergence Engineering, Yonsei University, Wonju 220-710 (Korea, Republic of); Lee, Kisung [Department of Bio-convergence Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Kim, Kyeong Min [Molecular Imaging Research Center, Korea Institute of Radiological and Medical Science, Seoul 139-706 (Korea, Republic of); Kim, Yongkwon; Joung, Jinhun [Nucare Medical System, Inc., Incheon 406-840 (Korea, Republic of)

    2016-06-21

    Positron emission tomography (PET) can be utilized in particle beam therapy to verify the dose distribution of the target volume as well as the accuracy of the treatment. We present an in-beam PET scanner that can be integrated into a particle beam therapy system. The proposed PET scanner consisted of 14 detector modules arranged in a C-shape to avoid blockage of the particle beam line by the detector modules. Each detector module was composed of a 9×9 array of 4.0 mm×4.0 mm×20.0 mm LYSO crystals optically coupled to four 29-mm-diameter PMTs using the photomultiplier-quadrant-sharing (PQS) technique. In this study, a Geant4 Application for Tomographic Emission (GATE) simulation study was conducted to design a C-shaped PET scanner and then experimental evaluation of the proposed design was performed. The spatial resolution and sensitivity were measured according to NEMA NU2-2007 standards and were 6.1 mm and 5.61 cps/kBq, respectively, which is in good agreement with our simulation, with an error rate of 12.0%. Taken together, our results demonstrate the feasibility of the proposed C-shaped in-beam PET system, which we expect will be useful for measuring dose distribution in particle therapy.

  10. Preliminary results of a prototype C-shaped PET designed for an in-beam PET system

    Science.gov (United States)

    Kim, Hyun-Il; Chung, Yong Hyun; Lee, Kisung; Kim, Kyeong Min; Kim, Yongkwon; Joung, Jinhun

    2016-06-01

    Positron emission tomography (PET) can be utilized in particle beam therapy to verify the dose distribution of the target volume as well as the accuracy of the treatment. We present an in-beam PET scanner that can be integrated into a particle beam therapy system. The proposed PET scanner consisted of 14 detector modules arranged in a C-shape to avoid blockage of the particle beam line by the detector modules. Each detector module was composed of a 9×9 array of 4.0 mm×4.0 mm×20.0 mm LYSO crystals optically coupled to four 29-mm-diameter PMTs using the photomultiplier-quadrant-sharing (PQS) technique. In this study, a Geant4 Application for Tomographic Emission (GATE) simulation study was conducted to design a C-shaped PET scanner and then experimental evaluation of the proposed design was performed. The spatial resolution and sensitivity were measured according to NEMA NU2-2007 standards and were 6.1 mm and 5.61 cps/kBq, respectively, which is in good agreement with our simulation, with an error rate of 12.0%. Taken together, our results demonstrate the feasibility of the proposed C-shaped in-beam PET system, which we expect will be useful for measuring dose distribution in particle therapy.

  11. Cost-effectiveness of PET and PET/Computed Tomography

    DEFF Research Database (Denmark)

    Gerke, Oke; Hermansson, Ronnie; Hess, Søren

    2015-01-01

    measure by means of incremental cost-effectiveness ratios when considering the replacement of the standard regimen by a new diagnostic procedure. This article discusses economic assessments of PET and PET/computed tomography reported until mid-July 2014. Forty-seven studies on cancer and noncancer...

  12. Dedicated monolithic infrared spectrometer for process monitoring

    Science.gov (United States)

    Chadha, Suneet; Kyle, William; Bolduc, Roy A.; Curtiss, Lawrence E.

    1999-12-01

    Foster-Miller has leveraged its innovations in IR fiber- optic probes and the recent development of a miniature spectrometer to build a novel IR sensor system for process applications. The developed sensor systems is a low-cost alternative to process FTIR and filter based systems. A monolithic wedge-grating optic provides the spectral dispersion with low cost thermopile point or array detectors picking off the diffracted wavelengths from the optic. The integrated optic provides spectral discrimination between 3- 12 micrometers with resolution at 8 cm-1 or better and high overall optical throughput. The device has a fixed cylindrical grating uniquely bonded to the edge of a ZnSe conditioning 'wedge'. The conditioning optic overcomes limitations of concave gratings as it accepts high angle light at the narrow end of the wedge and progressively conditions it to be near normal to the grating. On return, the diffracted wavelengths are concentrated on the discrete or array detector elements by the wedge, providing throughput comparable to that of an FTIR. The miniature spectrometer coupled to flow through liquid cells or multipass gas cells provides significant cost advantage over conventional sampling methodologies. Currently, we are investigating process applications for the petroleum and dairy markets. The sensor system eliminates the cost, complexity, reliability and bandwidth/resolution problems associated with either Fabry Perot or Michelson Interferometer based approaches for low-cost process applications.

  13. The Advanced Virgo monolithic fused silica suspension

    Energy Technology Data Exchange (ETDEWEB)

    Aisa, D.; Aisa, S.; Campeggi, C.; Colombini, M. [University of Perugia and INFN Perugia (Italy); Conte, A. [University of Roma Sapienza and INFN Roma (Italy); Farnesini, L. [University of Perugia and INFN Perugia (Italy); Majorana, E.; Mezzani, F. [University of Roma Sapienza and INFN Roma (Italy); Montani, M. [University of Urbino and INFN Firenze (Italy); Naticchioni, L.; Perciballi, M. [University of Roma Sapienza and INFN Roma (Italy); Piergiovanni, F. [University of Urbino and INFN Firenze (Italy); Piluso, A. [University of Perugia and INFN Perugia (Italy); Puppo, P., E-mail: paola.puppo@roma1.infn.it [University of Roma Sapienza and INFN Roma (Italy); Rapagnani, P. [University of Roma Sapienza and INFN Roma (Italy); Travasso, F. [University of Perugia and INFN Perugia (Italy); Vicerè, A. [University of Urbino and INFN Firenze (Italy); Vocca, H. [University of Perugia and INFN Perugia (Italy)

    2016-07-11

    The detection of gravitational waves is one of the most challenging prospects faced by experimental physicists. Suspension thermal noise is an important noise source at operating frequencies between approximately 10 and 30 Hz, and represents a limit to the sensitivity of the ground based interferometric gravitational wave detectors. Its effects can be reduced by minimizing the losses and by optimizing the geometry of the suspension fiber as well as its attachment system. In this proceeding we will describe the mirrors double stage monolithic suspension system to be used in the Advanced Virgo (AdV) detector. We also present the results of the thermal noise study, performed with the help of a finite elements model, taking into account the precise geometry of the fibers attachment systems on the suspension elements. We shall demonstrate the suitability of this suspension for installation in AdV. - Highlights: • Suspension system design for the test masses of the gravitational wave detectors. • Finite element model studies. • Suspension thermal noise studies.

  14. Large single crystal growth of MnWO4-type materials from high-temperature solutions

    Science.gov (United States)

    Gattermann, U.; Röska, B.; Paulmann, C.; Park, S.-H.

    2016-11-01

    A simple high-temperature growth apparatus was constructed to obtain large crystals of chemically gradient (In, Na)-doped MnWO4solid-solutions. This paper presents the crystal growth and characterisation of both MnWO4and epitaxially grown (In, Na): MnWO4crystals on MnWO4. These large monolithic crystals were made in two steps: A MnWO4 crystal was grown in the crystallographic main direction [001] applying the Czochralski method, followed by the top seeded growth of (In, Na): MnWO4 solid-solutions with an oriented seed crystal of MnWO4. Such a monolithic crystal will serve to fundamental investigation of coupling properties at boundaries between various multiferroic MnWO4-typesolid-solutions.

  15. Synthesis of hierarchical porous carbon monoliths with incorporated metal-organic frameworks for enhancing volumetric based CO₂ capture capability.

    Science.gov (United States)

    Qian, Dan; Lei, Cheng; Hao, Guang-Ping; Li, Wen-Cui; Lu, An-Hui

    2012-11-01

    This work aims to optimize the structural features of hierarchical porous carbon monolith (HCM) by incorporating the advantages of metal-organic frameworks (MOFs) (Cu₃(BTC)₂) to maximize the volumetric based CO₂ capture capability (CO₂ capacity in cm³ per cm³ adsorbent), which is seriously required for the practical application of CO₂ capture. The monolithic HCM was used as a matrix, in which Cu₃(BTC)₂ was in situ synthesized, to form HCM-Cu₃(BTC)₂ composites by a step-by-step impregnation and crystallization method. The resulted HCM-Cu₃(BTC)₂ composites, which retain the monolithic shape and exhibit unique hybrid structure features of both HCM and Cu₃(BTC)₂, show high CO₂ uptake of 22.7 cm³ cm⁻³ on a volumetric basis. This value is nearly as twice as the uptake of original HCM. The dynamic gas separation measurement of HCM-Cu₃(BTC)₂, using 16% (v/v) CO₂ in N₂ as feedstock, illustrates that CO₂ can be easily separated from N₂ under the ambient conditions and achieves a high separation factor for CO₂ over N₂, ranging from 67 to 100, reflecting a strongly competitive CO₂ adsorption by the composite. A facile CO₂ release can be realized by purging an argon flow through the fixed-bed adsorber at 25 °C, indicating the good regeneration ability.

  16. Monolithic supports with unique geometries and enhanced mass transfer.

    Energy Technology Data Exchange (ETDEWEB)

    Stuecker, John Nicholas; Ferrizz, Robert Matthew; Cesarano, Joseph, III; Miller, James Edward

    2004-01-01

    The catalytic combustion of natural gas has been the topic of much research over the past decade. Interest in this technology results from a desire to decrease or eliminate the emissions of harmful nitrogen oxides (NOX) from gas turbine power plants. A low-pressure drop catalyst support, such as a ceramic monolith, is ideal for this high-temperature, high-flow application. A drawback to the traditional honeycomb monoliths under these operating conditions is poor mass transfer to the catalyst surface in the straight-through channels. 'Robocasting' is a unique process developed at Sandia National Laboratories that can be used to manufacture ceramic monoliths with alternative 3-dimensional geometries, providing tortuous pathways to increase mass transfer while maintaining low pressure drops. This report details the mass transfer effects for novel 3-dimensional robocast monoliths, traditional honeycomb-type monoliths, and ceramic foams. The mass transfer limit is experimentally determined using the probe reaction of CO oxidation over a Pt / {gamma}-Al{sub 2}O{sub 3} catalyst, and the pressure drop is measured for each monolith sample. Conversion versus temperature data is analyzed quantitatively using well-known dimensionless mass transfer parameters. The results show that, relative to the honeycomb monolith support, considerable improvement in mass transfer efficiency is observed for robocast samples synthesized using an FCC-like geometry of alternating rods. Also, there is clearly a trade-off between enhanced mass transfer and increased pressure drop, which can be optimized depending on the particular demands of a given application.

  17. Development of a novel depth of interaction PET detector using highly multiplexed G-APD cross-strip encoding

    Energy Technology Data Exchange (ETDEWEB)

    Kolb, A., E-mail: armin.kolb@med.uni-tuebingen.de; Parl, C.; Liu, C. C.; Pichler, B. J. [Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, 72076 Tübingen (Germany); Mantlik, F. [Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, 72076 Tübingen, Germany and Department of Empirical Inference, Max Planck Institute for Intelligent Systems, 72076 Tübingen (Germany); Lorenz, E. [Max Planck Institute for Physics, Föhringer Ring 6, 80805 München (Germany); Renker, D. [Department of Physics, Technische Universität München, 85748 Garching (Germany)

    2014-08-15

    Purpose: The aim of this study was to develop a prototype PET detector module for a combined small animal positron emission tomography and magnetic resonance imaging (PET/MRI) system. The most important factor for small animal imaging applications is the detection sensitivity of the PET camera, which can be optimized by utilizing longer scintillation crystals. At the same time, small animal PET systems must yield a high spatial resolution. The measured object is very close to the PET detector because the bore diameter of a high field animal MR scanner is limited. When used in combination with long scintillation crystals, these small-bore PET systems generate parallax errors that ultimately lead to a decreased spatial resolution. Thus, we developed a depth of interaction (DoI) encoding PET detector module that has a uniform spatial resolution across the whole field of view (FOV), high detection sensitivity, compactness, and insensitivity to magnetic fields. Methods: The approach was based on Geiger mode avalanche photodiode (G-APD) detectors with cross-strip encoding. The number of readout channels was reduced by a factor of 36 for the chosen block elements. Two 12 × 2 G-APD strip arrays (25μm cells) were placed perpendicular on each face of a 12 × 12 lutetium oxyorthosilicate crystal block with a crystal size of 1.55 × 1.55 × 20 mm. The strip arrays were multiplexed into two channels and used to calculate the x, y coordinates for each array and the deposited energy. The DoI was measured in step sizes of 1.8 mm by a collimated {sup 18}F source. The coincident resolved time (CRT) was analyzed at all DoI positions by acquiring the waveform for each event and applying a digital leading edge discriminator. Results: All 144 crystals were well resolved in the crystal flood map. The average full width half maximum (FWHM) energy resolution of the detector was 12.8% ± 1.5% with a FWHM CRT of 1.14 ± 0.02 ns. The average FWHM DoI resolution over 12 crystals was 2.90

  18. Development of a novel depth of interaction PET detector using highly multiplexed G-APD cross-strip encoding.

    Science.gov (United States)

    Kolb, A; Parl, C; Mantlik, F; Liu, C C; Lorenz, E; Renker, D; Pichler, B J

    2014-08-01

    The aim of this study was to develop a prototype PET detector module for a combined small animal positron emission tomography and magnetic resonance imaging (PET/MRI) system. The most important factor for small animal imaging applications is the detection sensitivity of the PET camera, which can be optimized by utilizing longer scintillation crystals. At the same time, small animal PET systems must yield a high spatial resolution. The measured object is very close to the PET detector because the bore diameter of a high field animal MR scanner is limited. When used in combination with long scintillation crystals, these small-bore PET systems generate parallax errors that ultimately lead to a decreased spatial resolution. Thus, we developed a depth of interaction (DoI) encoding PET detector module that has a uniform spatial resolution across the whole field of view (FOV), high detection sensitivity, compactness, and insensitivity to magnetic fields. The approach was based on Geiger mode avalanche photodiode (G-APD) detectors with cross-strip encoding. The number of readout channels was reduced by a factor of 36 for the chosen block elements. Two 12 × 2 G-APD strip arrays (25 μm cells) were placed perpendicular on each face of a 12 × 12 lutetium oxyorthosilicate crystal block with a crystal size of 1.55 × 1.55 × 20 mm. The strip arrays were multiplexed into two channels and used to calculate the x, y coordinates for each array and the deposited energy. The DoI was measured in step sizes of 1.8 mm by a collimated (18)F source. The coincident resolved time (CRT) was analyzed at all DoI positions by acquiring the waveform for each event and applying a digital leading edge discriminator. All 144 crystals were well resolved in the crystal flood map. The average full width half maximum (FWHM) energy resolution of the detector was 12.8% ± 1.5% with a FWHM CRT of 1.14 ± 0.02 ns. The average FWHM DoI resolution over 12 crystals was 2.90 ± 0.15 mm. The novel DoI PET

  19. PET and PET/CT in clinical cardiology

    Energy Technology Data Exchange (ETDEWEB)

    Won, Kyoung Sook [Keimyung University School of Medicine, Daegu (Korea, Republic of)

    2005-02-15

    Cardiac PET emerged as a powerful tool that allowed in vivo quantification of physiologic processes including myocardial perfusion and metabolism, as well as neuronal and receptor function for more than 25 years. Now PET imaging has been playing an important role in the clinical evaluation of patients with known or suspected ischemic heart disease. This important clinical role is expected to grow with the availability of PET/CT scanner that allow a true integration of structure and function. The objective of this review is to provide and update on the current and future role of PET in clinical cardiology with a special eye on the great opportunities now offered by PET/CT.

  20. A Monte-Carlo based model of the AX-PET demonstrator and its experimental validation.

    Science.gov (United States)

    Solevi, P; Oliver, J F; Gillam, J E; Bolle, E; Casella, C; Chesi, E; De Leo, R; Dissertori, G; Fanti, V; Heller, M; Lai, M; Lustermann, W; Nappi, E; Pauss, F; Rudge, A; Ruotsalainen, U; Schinzel, D; Schneider, T; Séguinot, J; Stapnes, S; Weilhammer, P; Tuna, U; Joram, C; Rafecas, M

    2013-08-21

    AX-PET is a novel PET detector based on axially oriented crystals and orthogonal wavelength shifter (WLS) strips, both individually read out by silicon photo-multipliers. Its design decouples sensitivity and spatial resolution, by reducing the parallax error due to the layered arrangement of the crystals. Additionally the granularity of AX-PET enhances the capability to track photons within the detector yielding a large fraction of inter-crystal scatter events. These events, if properly processed, can be included in the reconstruction stage further increasing the sensitivity. Its unique features require dedicated Monte-Carlo simulations, enabling the development of the device, interpreting data and allowing the development of reconstruction codes. At the same time the non-conventional design of AX-PET poses several challenges to the simulation and modeling tasks, mostly related to the light transport and distribution within the crystals and WLS strips, as well as the electronics readout. In this work we present a hybrid simulation tool based on an analytical model and a Monte-Carlo based description of the AX-PET demonstrator. It was extensively validated against experimental data, providing excellent agreement.

  1. 10 "Poison Pills" for Pets

    Science.gov (United States)

    ... by Animal/Species Browse by Topic Browse by Discipline Resources Tools for K-12 Educators You are here: Home | Public Resources | Pet ... of all phone calls to the ASPCA Animal Poison Control Center (APCC) are about human medications. Your pet can easily ingest dropped pills ...

  2. Small Molecule PET-Radiopharmaceuticals

    NARCIS (Netherlands)

    Elsinga, Philip H.; Dierckx, Rudi A. J. O.

    2014-01-01

    This review describes several aspects required for the development of small molecule PET-tracers. Design and selection criteria are important to consider before starting to develop novel PET-tracers. Principles and latest trends in C-11 and F-18-radiochemistry are summarized. In addition an update o

  3. Welfare assessment in pet rabbits

    NARCIS (Netherlands)

    Schepers, F.; Koene, P.; Beerda, B.

    2009-01-01

    One million pet rabbits are kept in The Netherlands, but there are no data available on their behaviour and welfare. This study seeks to assess the welfare of pet rabbits in Dutch households and is a first step in the development of a welfare assessment system. In an internet survey, housing

  4. Imaging results and TOF studies with axial PET detectors

    CERN Document Server

    Joram, Christian

    2013-01-01

    We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the held of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The Fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations ( <2 mm FWHM in all three coordinates over the complete held of view) and also demonstrated the ability to include Compton interactions (inter-cr...

  5. Neurotransmission imaging by PET

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Akihiro; Suhara, Tetsuya [National Inst. of Radiological Sciences, Chiba (Japan)

    2001-08-01

    PET studies on neurotransmission in psychological disorders to evaluate abnormal neurotransmission and therapeutic effects are thoroughly reviewed by type of major neurotransmitters. Studies on dopaminergic neurotransmission have focused on the function of dopamine D{sub 2} receptors, receptor subtypes, such as the D{sub 1} receptor, and ligands, such as transporters. PET studies of dopamine D{sub 2} receptor, which began in the early 1980s, have predominantly been performed in schizophrenia, and most have failed to detect any statistically significant differences between schizophrenia patients and controls. The studies in the early 1980s were performed by using [{sup 11}C]N-methyl-spiperone (NMSP) and [{sup 11}C]raclopride, ligands for striatal dopamine D{sub 2} receptors. [{sup 11}C]FLB457, which has much higher affinity for D{sub 2} receptors than raclopride, began to be used in the 1990s. Dopamine D{sub 2} occupancy after drug ingestion has also been investigated to clarify the mechanisms and effects of antipsychotic drugs, and there have also been studies on the effect of aging and personality traits on dopamine D{sub 2} receptor levels in healthy subjects. In studies on dopamine receptor subtypes other than D{sub 2}, dopamine D{sub 1} receptors have been studied in connection with assessments of cognitive functions. Most studies on dopamine transporters have been related to drug dependence. Serotonin 5-HT{sub 2A} receptors have been studied with [{sup 11}C]NMSP in schizophrenia patients, while studies of another serotonin receptor subtype, 5-HT{sub 1A} receptors, have been mainly conducted in patients with depression. [{sup 11}C]NMSP PET showed no difference between schizophrenia patients who had not undergone phamacotherapy and normal subjects. Because serotonin selective reuptake inhibitors (SSRIs) affect serotonin transporters, and abnormalities in serotonin transporters detected in mood disorders, PET ligands for serotonin transporters have increasingly

  6. Advanced Gasification Mercury/Trace Metal Control with Monolith Traps

    Energy Technology Data Exchange (ETDEWEB)

    Musich, Mark; Swanson, Michael; Dunham, Grant; Stanislowski, Joshua

    2010-10-05

    Two Corning monoliths and a non-carbon-based material have been identified as potential additives for mercury capture in syngas at temperatures above 400°F and pressure of 600 psig. A new Corning monolith formulation, GR-F1-2189, described as an active sample appeared to be the best monolith tested to date. The Corning SR Liquid monolith concept continues to be a strong candidate for mercury capture. Both monolith types allowed mercury reduction to below 5-μg/m{sup 3} (~5 ppb), a current U.S. Department of Energy (DOE) goal for trace metal control. Preparation methods for formulating the SR Liquid monolith impacted the ability of the monolith to capture mercury. The Energy & Environmental Research Center (EERC)-prepared Noncarbon Sorbents 1 and 2 appeared to offer potential for sustained and significant reduction of mercury concentration in the simulated fuel gas. The Noncarbon Sorbent 1 allowed sustained mercury reduction to below 5-μg/m{sup 3} (~5 ppb). The non-carbon-based sorbent appeared to offer the potential for regeneration, that is, desorption of mercury by temperature swing (using nitrogen and steam at temperatures above where adsorption takes place). A Corning cordierite monolith treated with a Group IB metal offered limited potential as a mercury sorbent. However, a Corning carbon-based monolith containing prereduced metallic species similar to those found on the noncarbon sorbents did not exhibit significant or sustained mercury reduction. EERC sorbents prepared with Group IB and IIB selenide appeared to have some promise for mercury capture. Unfortunately, these sorbents also released Se, as was evidenced by the measurement of H2Se in the effluent gas. All sorbents tested with arsine or hydrogen selenide, including Corning monoliths and the Group IB and IIB metal-based materials, showed an ability to capture arsine or hydrogen selenide at 400°F and 600 psig. Based on current testing, the noncarbon metal-based sorbents appear to be the most

  7. ADVANCED GASIFICATION MERCURY/TRACE METAL CONTROL WITH MONOLITH TRAPS

    Energy Technology Data Exchange (ETDEWEB)

    Mark A. Musich; Michael L. Swanson; Grant E. Dunham; Joshua J. Stanislowski

    2010-07-31

    Two Corning monoliths and a non-carbon-based material have been identified as potential additives for mercury capture in syngas at temperatures above 400°F and pressure of 600 psig. A new Corning monolith formulation, GR-F1-2189, described as an active sample appeared to be the best monolith tested to date. The Corning SR Liquid monolith concept continues to be a strong candidate for mercury capture. Both monolith types allowed mercury reduction to below 5-μg/m3 (~5 ppb), a current U.S. Department of Energy (DOE) goal for trace metal control. Preparation methods for formulating the SR Liquid monolith impacted the ability of the monolith to capture mercury. The Energy & Environmental Research Center (EERC)-prepared Noncarbon Sorbents 1 and 2 appeared to offer potential for sustained and significant reduction of mercury concentration in the simulated fuel gas. The Noncarbon Sorbent 1 allowed sustained mercury reduction to below 5-μg/m3 (~5 ppb). The non-carbon-based sorbent appeared to offer the potential for regeneration, that is, desorption of mercury by temperature swing (using nitrogen and steam at temperatures above where adsorption takes place). A Corning cordierite monolith treated with a Group IB metal offered limited potential as a mercury sorbent. However, a Corning carbon-based monolith containing prereduced metallic species similar to those found on the noncarbon sorbents did not exhibit significant or sustained mercury reduction. EERC sorbents prepared with Group IB and IIB selenide appeared to have some promise for mercury capture. Unfortunately, these sorbents also released Se, as was evidenced by the measurement of H2Se in the effluent gas. All sorbents tested with arsine or hydrogen selenide, including Corning monoliths and the Group IB and IIB metal-based materials, showed an ability to capture arsine or hydrogen selenide at 400°F and 600 psig. Based on current testing, the noncarbon metal-based sorbents appear to be the most effective arsine

  8. New Graphene Form of Nanoporous Monolith for Excellent Energy Storage.

    Science.gov (United States)

    Bi, Hui; Lin, Tianquan; Xu, Feng; Tang, Yufeng; Liu, Zhanqiang; Huang, Fuqiang

    2016-01-13

    Extraordinary tubular graphene cellular material of a tetrahedrally connected covalent structure was very recently discovered as a new supermaterial with ultralight, ultrastiff, superelastic, and excellent conductive characteristics, but no high specific surface area will keep it from any next-generation energy storage applications. Herein, we prepare another new graphene monolith of mesoporous graphene-filled tubes instead of hollow tubes in the reported cellular structure. This graphene nanoporous monolith is also composed of covalently bonded carbon network possessing high specific surface area of ∼1590 m(2) g(-1) and electrical conductivity of ∼32 S cm(-1), superior to graphene aerogels and porous graphene forms self-assembled by graphene oxide. This 3D graphene monolith can support over 10 000 times its own weight, significantly superior to CNT and graphene cellular materials with a similar density. Furthermore, pseudocapacitance-active functional groups are introduced into the new nanoporous graphene monolith as an electrode material in electrochemical capacitors. Surprisingly, the electrode of 3D mesoporous graphene has a specific capacitance of 303 F g(-1) and maintains over 98% retention after 10 000 cycles, belonging to the list for the best carbon-based active materials. The macroscopic mesoporous graphene monolith suggests the great potential as an electrode for supercapacitors in energy storage areas.

  9. Recent advances in polymer monoliths for ion-exchange chromatography.

    Science.gov (United States)

    Nordborg, Anna; Hilder, Emily F

    2009-05-01

    The use of polymeric materials in ion-exchange chromatography applications is advantageous because of their typically high mechanical stability and tolerance of a wide range of pH conditions. The possibility of using polymeric monoliths in ion-exchange chromatography is therefore obvious and many of the same strategies developed for polymeric particles have been adapted for use with polymeric monoliths. In this review different strategies for the synthesis of polymeric monoliths with ion-exchange functionality are discussed. The incorporation of ion-exchange functionality by co-polymerization is included, as also are different post-polymerization alterations to the monolith surface such as grafting. The formulations and strategies presented include materials intended for use in analytical separations in ion-exchange chromatography, sample pre-treatment or enrichment applications, and materials for capillary electrochromatography. Finally, examples of the use of polymeric monoliths in ion-exchange chromatography applications are included with examples published in the years 2003 to 2008.

  10. HPLC analysis of synthetic polymers on short monolithic columns.

    Science.gov (United States)

    Maksimova, Elena; Vlakh, Evgenia; Sinitsyna, Ekaterina; Tennikova, Tatiana

    2013-12-01

    Ultrashort monolithic columns (disks) were thoroughly studied as efficient stationary phases for precipitation-dissolution chromatography of synthetic polymers. Gradient elution mode was applied in all chromatographic runs. The mixtures of different flexible chain homopolymers, such as polystyrenes, poly(methyl methacrylates), and poly(tert-butylmethacrylates) were separated according to their molecular weights on both commercial poly(styrene-co-divinylbenzene) disks (12 id × 3 mm and 5 × 5 mm) and lab-made monolithic columns (4.6 id × 50 mm) filled with supports of different hydrophobicity. The experimental conditions were optimized to reach fast and highly efficient separation. It was observed that, similar to the separation of monoliths of other classes of (macro)molecules (proteins, DNA, oligonucleotides), the length of column did not affect the peak resolution. A comparison of the retention properties of the poly(styrene-co-divinylbenzene) disk-shaped monoliths with those based on poly(lauryl methacrylate-co-ethylene dimethacrylate), poly(butyl methacrylate-co-ethylene dimethacrylate), and poly(glycidyl methacrylate-co-ethylene dimethacrylate) supports demonstrated the obvious effect of surface chemistry on the resolution factor. Additionally, the results of the discussed chromatographic mode on the fast determination of the molecular weights of homopolymers used in this study were compared to those established by SEC on columns packed with sorbent beads of a similar nature to the monoliths. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Edge chipping and flexural resistance of monolithic ceramics☆

    Science.gov (United States)

    Zhang, Yu; Lee, James J.-W.; Srikanth, Ramanathan; Lawn, Brian R.

    2014-01-01

    Objective Test the hypothesis that monolithic ceramics can be developed with combined esthetics and superior fracture resistance to circumvent processing and performance drawbacks of traditional all-ceramic crowns and fixed-dental-prostheses consisting of a hard and strong core with an esthetic porcelain veneer. Specifically, to demonstrate that monolithic prostheses can be produced with a much reduced susceptibility to fracture. Methods Protocols were applied for quantifying resistance to chipping as well as resistance to flexural failure in two classes of dental ceramic, microstructurally-modified zirconias and lithium disilicate glass–ceramics. A sharp indenter was used to induce chips near the edges of flat-layer specimens, and the results compared with predictions from a critical load equation. The critical loads required to produce cementation surface failure in monolithic specimens bonded to dentin were computed from established flexural strength relations and the predictions validated with experimental data. Results Monolithic zirconias have superior chipping and flexural fracture resistance relative to their veneered counterparts. While they have superior esthetics, glass–ceramics exhibit lower strength but higher chip fracture resistance relative to porcelain-veneered zirconias. Significance The study suggests a promising future for new and improved monolithic ceramic restorations, with combined durability and acceptable esthetics. PMID:24139756

  12. Supplements for exotic pets.

    Science.gov (United States)

    Mejia-Fava, Johanna; Colitz, Carmen M H

    2014-09-01

    The use of supplements has become commonplace in an effort to complement traditional therapy and as part of long-term preventive health plans. This article discusses historical and present uses of antioxidants, vitamins, and herbs. By complementing traditional medicine with holistic and alternative nutrition and supplements, the overall health and wellness of exotic pets can be enhanced and balanced. Further research is needed for understanding the strengths and uses of supplements in exotic species. Going back to the animals' origin and roots bring clinicians closer to nature and its healing powers.

  13. PET and PET/CT - relevance in breast cancer patients; PET und PET/CT - Stellenwert beim Mammakarzinom

    Energy Technology Data Exchange (ETDEWEB)

    Palmedo, H. [Klinik und Poliklinik fuer Nuklearmedizin, Universitaetsklinikum Bonn (Germany)

    2004-12-01

    Breast cancer is the most frequent malignant tumor of women in Germany. In spite of an increasing incidence mortality has slightly declined most likely due to improvements in diagnosis and therapy of the disease. FDG-PET has a high diagnostic accuracy for the detection of lymph node and distant metastases. However, PET is no alternative to axillary dissection or sentinel node biopsy because sensitivity for small lymph node metastases is limited. For N-staging, FDG-PET delivers valuable information if mammaria-interna or mediastinal lymph node disease has to be proven (1b-indication). Individually, PET can add important diagnostic information in patients with suspected distant metastases but unsuspicious or equivocal conventional imaging (2-indication). FDG-PET shows unique and favourable properties for early therapy monitoring during preoperative chemotherapy. Larger studies have to confirm these results. (orig.)

  14. Design and performance from an integrated PET/MRI system for small animals.

    Science.gov (United States)

    Yamamoto, Seiichi; Imaizumi, Masao; Kanai, Yasukazu; Tatsumi, Mitsuaki; Aoki, Masaaki; Sugiyama, Eiji; Kawakami, Makoto; Shimosegawa, Eku; Hatazawa, Jun

    2010-02-01

    Although simultaneous measurements of PET and magnetic resonance imaging (MRI) can provide interesting results in molecular imaging research, most of the combined systems are huge and animal handling in the system is not easy. To minimize these problems, we developed a compact integrated PET/MRI (iPET/MRI) system for small animals. For the iPET/MRI system, a new MR-compatible PET and a permanent magnet open MRI were designed. In the MRI, a tunnel is opened at the yoke of the magnet. The position-sensitive photo-multiplier tubes (PSPMTs) of the MR-compatible PET are positioned at the back of the yoke where the magnetic field is sufficiently low. The scintillators for the PET system are positioned at the center of the MRI magnets, and the direction of the scintillation photons is changed by slanted light guides, and they are fed to the PSPMTs by 75 cm long optical fiber bundles. The PET detectors employed two types of LGSO crystals (1.9 mm x 2.2 mm x 6 mm and 7 mm) with different decay times (33 and 43 ns) for depth of interaction detection. Sixteen optical fiber-based block detectors are arranged in a 112 mm diameter ring. The transaxial field-of-view (FOV) of the PET system is ~80 mm, and the axial FOV is 21 mm which can be enlarged by the axial motion of the PET detector ring during MRI acquisition. The transaxial and axial resolutions at the center of the PET system was 2.9 and 2.4 mm FWHM, respectively. The absolute sensitivity was 1.5% at the center of the axial FOV. Phantom images revealed no artifact in either the PET or MRI images. We successfully obtained simultaneously measured small animal images using the iPET/MRI system. The open geometry of the developed iPET/ MRI facilitates easy accessibility to the subject. The iPET/ MRI system appears to be a promising tool for molecular imaging research.

  15. Readout strategy of an electro-optical coupled PET detector for time-of-flight PET/MRI

    Science.gov (United States)

    Bieniosek, M. F.; Olcott, P. D.; Levin, C. S.

    2013-10-01

    Combining PET with MRI in a single system provides clinicians with complementary molecular and anatomical information. However, existing integrated PET/MRI systems do not have time-of-flight (ToF) PET capabilities. This work describes an MRI-compatible front-end electronic system with ToF capabilities. The approach employs a fast arrival-time pickoff comparator to digitize the timing information, and a laser diode to drive a 10 m fiber-optic cable to optically transmit asynchronous timing information to a photodiode receiver readout system. The FWHM jitter of the comparator and this electo-optical link is 11.5 ps in response to a fast digital pulse. When configured with LYSO scintillation crystals and Hamamatsu MPPC silicon photo-multipliers the comparator and electro-optical link achieved a 511 keV coincidence time resolution of 254.7 ps +/- 8.0 ps FWHM with 3 × 3 × 20 mm3 crystals and 166.5 +/- 2.5 ps FWHM with 3 × 3 × 5 mm3 crystals.

  16. Monolithic View of Galaxy Formation and Evolution

    Directory of Open Access Journals (Sweden)

    Cesare Chiosi

    2014-07-01

    Full Text Available We review and critically discuss the current understanding of galaxy formation and evolution limited to Early Type Galaxies (ETGs as inferred from the observational data and briefly contrast the hierarchical and quasi-monolithic paradigms of formation and evolution. Since in Cold Dark Matter (CDM cosmogony small scale structures typically collapse early and form low-mass haloes that subsequently can merge to assembly larger haloes, galaxies formed in the gravitational potential well of a halo are also expected to merge thus assembling their mass hierarchically. Mergers should occur all over the Hubble time and large mass galaxies should be in place only recently. However, recent observations of high redshift galaxies tell a different story: massive ETGs are already in place at high redshift. To this aim, we propose here a revision of the quasi-monolithic scenario as an alternative to the hierarchical one, in which mass assembling should occur in early stages of a galaxy lifetime and present recent models of ETGs made of Dark and Baryonic Matter in a Λ-CDM Universe that obey the latter scheme. The galaxies are followed from the detachment from the linear regime and Hubble flow at z ≥ 20 down to the stage of nearly complete assembly of the stellar content (z ∼ 2 − 1 and beyond.  It is found that the total mass (Mh = MDM + MBM and/or initial over-density of the proto-galaxy drive the subsequent star formation histories (SFH. Massive galaxies (Mh ~ _1012M⊙ experience a single, intense burst of star formation (with rates ≥ 103M⊙/yr at early epochs, consistently with observations, with a weak dependence on the initial over-density; intermediate mass haloes (Mh~_ 1010 − 1011M⊙ have star formation histories that strongly depend on their initial over-density; finally, low mass haloes (Mh ~_ 109M⊙ always have erratic, burst-like star forming histories. The present-day properties (morphology, structure, chemistry and photometry of the

  17. Monolithic Solid Oxide Fuel Cell development

    Science.gov (United States)

    Myles, K. M.; McPheeters, C. C.

    1989-12-01

    The Monolithic Solid Oxide Fuel Cell (MSOFC) is an oxide-ceramic structure in which appropriate electronic and ionic conductors are fabricated in a honeycomb shape similar to a block of corrugated paperboard. These electronic and ionic conductors are arranged to provide short conduction paths to minimize resistive losses. The power density achievable with the MSOFC is expected to be about 8 kW/kg or 4 kW/L, at fuel efficienceis over 50 percent, because of small cell size and low resistive losses in the materials. The MSOFC operates in the range of 700 to 1000 C, at which temperatures rapid reform of hydrocarbon fuels is expected within the nickel-YSZ fuel channels. Tape casting and hot roll calendering are used to fabricate the MSOFC structure. The performance of the MSOFC has improved significantly during the course of development. The limitation of this system, based on materials resistance alone without interfacial resistances, is 0.093 ohm-sq cm area-specific resistance (ASR). The current typical performance of MSOFC single cells is characterized by ASRs of about 0.4 to 0.5 ohm-sq cm. With further development the ASR is expected to be reduced below 0.2 ohm-sq cm, which will result in power levels greater than 1.4 W/sq cm. The feasibility of the MSOFC concept was proven, and the performance was dramatically improved. The differences in thermal expansion coefficients and firing shrinkages among the fuel cell materials were minimized. As a result of good matching of these properties, the MSOFC structure was successfully fabricated with few defects, and the system shows excellent promise for development into a practical power source.

  18. FDG PET imaging dementia

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Byeong Cheol [Kyungpook National University Medical School and Kyungpook National University Hospital, Daegu (Korea, Republic of)

    2007-04-15

    Dementia is a major burden for many countries including South Korea, where life expectancy is continuously growing and the proportion of aged people is rapidly growing. Neurodegenerative disorders, such as, Alzheimer disease, dementia with Lewy bodies, frontotemporal dementia. Parkinson disease, progressive supranuclear palsy, corticobasal degeneration, Huntington disease, can cause dementia, and cerebrovascular disease also can cause dementia. Depression or hypothyroidism also can cause cognitive deficits, but they are reversible by management of underlying cause unlike the forementioned dementias. Therefore these are called pseudodementia. We are entering an era of dementia care that will be based upon the identification of potentially modifiable risk factors and early disease markers, and the application of new drugs postpone progression of dementias or target specific proteins that cause dementia. Efficient pharmacologic treatment of dementia needs not only to distinguish underlying causes of dementia but also to be installed as soon as possible. Therefore, differential diagnosis and early diagnosis of dementia are utmost importance. F-18 FDG PET is useful for clarifying dementing diseases and is also useful for early detection of the disease. Purpose of this article is to review the current value of FDG PET for dementing diseases including differential diagnosis of dementia and prediction of evolving dementia.

  19. WE-AB-204-10: Evaluation of a Novel Dedicated Breast PET System (Mammi-PET)

    Energy Technology Data Exchange (ETDEWEB)

    Long, Z; Swanson, T; O’Connor, M [Mayo Clinic, Rochester, MN (United States)

    2015-06-15

    Purpose: To evaluate the performance characteristics of a novel dedicated breast PET system (Mammi-PET, Oncovision). The system has 2 detector rings giving axial/transaxial field of view of 8/17 cm. Each ring consists of 12 monolithic LYSO modules coupled to PSPMTs. Methods: Uniformity, sensitivity, energy and spatial resolution were measured according to NEMA standards. Count rate performance was investigated using a source of F-18 (1384uCi) decayed over 5 half-lives. A prototype PET phantom was imaged for 20 min to evaluate image quality, recovery coefficients and partial volume effects. Under an IRB-approved protocol, 11 patients who just underwent whole body PET/CT exams were imaged prone with the breast pendulant at 5–10 minutes/breast. Image quality was assessed with and without scatter/attenuation correction and using different reconstruction algorithms. Results: Integral/differential uniformity were 9.8%/6.0% respectively. System sensitivity was 2.3% on axis, 2.2% and 2.8% at 3.8 cm and 7.8 cm off-axis. Mean energy resolution of all modules was 23.3%. Spatial resolution (FWHM) was 1.82 mm and 2.90 mm on axis and 5.8 cm off axis. Three cylinders (14 mm diameter) in the PET phantom were filled with activity concentration ratios of 4:1, 3:1, and 2:1 relative to the background. Measured cylinder to background ratios were 2.6, 1.8 and 1.5 (without corrections) and 3.6, 2.3 and 1.5 (with attenuation/scatter correction). Five cylinders (14, 10, 6, 4 and 2 mm diameter) each with an activity ratio of 4:1 were measured and showed recovery coefficients of 1, 0.66, 0.45, 0.18 and 0.18 (without corrections), and 1, 0.53, 0.30, 0.13 and 0 (with attenuation/scatter correction). Optimal phantom image quality was obtained with 3D MLEM algorithm, >20 iterations and without attenuation/scatter correction. Conclusion: The MAMMI system demonstrated good performance characteristics. Further work is needed to determine the optimal reconstruction parameters for qualitative and

  20. 36 CFR 2.15 - Pets.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Pets. 2.15 Section 2.15 Parks... USE AND RECREATION § 2.15 Pets. (a) The following are prohibited: (1) Possessing a pet in a public... area closed to the possession of pets by the superintendent. This subparagraph shall not apply to...

  1. 36 CFR 1002.15 - Pets.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Pets. 1002.15 Section 1002.15....15 Pets. (a) The following are prohibited: (1) Possessing a pet in a public building, public... possession of pets by the Board. This paragraph shall not apply to guide dogs accompanying visually...

  2. 7 CFR 502.11 - Pets.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Pets. 502.11 Section 502.11 Agriculture Regulations of... CONDUCT ON BELTSVILLE AGRICULTURE RESEARCH CENTER PROPERTY, BELTSVILLE, MARYLAND § 502.11 Pets. Pets... vaccinations. Pets that are the property of employees residing on BARC must be up to date on their...

  3. Monolithic series-connected gallium arsenide converter development

    Energy Technology Data Exchange (ETDEWEB)

    Spitzer, M.B.; McClelland, R.W.; Dingle, B.D.; Dingle, J.E.; Hill, D.S. (Kopin Corp., Taunton, MA (United States)); Rose, B.H. (Sandia National Labs., Albuquerque, NM (United States))

    1991-01-01

    We report the development of monolithic GaAs photovoltaic devices intended to convert light generated by a laser or other bright source to electricity. The converters described here can provide higher operating voltage than is possible using a single-junction converter, owing to use of a monolithic circuit that forms a planar series-connected string of single-junction sub-cells. This planar monolithic circuit is arranged to deliver the desired voltage and current during operation at the maximum power point. The paper describes two-, six-, and twelve-junction converters intended for illumination by a laser diode with a wavelength of 0.8 {mu}m. Design and characterization data are presented for optical power in the range of 100 mW to 1 W. The best conversion efficiency exceeds 50%. 9 refs., 4 figs., 2 tabs.

  4. Design of Monolithic Integrator for Strain-to-Frequency Converter

    Directory of Open Access Journals (Sweden)

    Tuan Mohd. Khairi Tuan Mat

    2012-01-01

    Full Text Available Strain-to-Frequency converter (SFC is a one of the analog conditioner tools that converts any strain signal to the frequency signal. The basic concept of SFC is by detecting any changing of strains, then converting the strain to the voltage signal and converting the voltage signal to the frequency signal. This tool consists of 3 main  components which are strain gauge, differential integrator and comparator. This paper presents the designing and analysis of monolithic integrator that to be used in the Strain-toFrequency converter. The primary goal is to design and simulate the performance of monolithic integrator for SFC using GATEWAY Silvaco Electronic Design Automation (S EDA tools and EXPERT software. The performances of SFC using the designed monolithic integrator are also investigated.

  5. Molecularly imprinted macroporous monolithic materials for protein recognition

    Institute of Scientific and Technical Information of China (English)

    Qi Liang Deng; Yan Li Li; Li Hua Zhang; Yu Kui Zhang

    2011-01-01

    Synthetic materials that can specifically recognize proteins will find wide application in many fields. In this report, bovine serum albumin was chosen as the template protein. Acrylamide and N, N'-methylenebisacrylamide were employed as the functional and cross-linker monomers, respectively. Molecularly imprinted macroporous monolithic materials that can preferentially bind the template protein in an aqueous environment were prepared by combination of molecular imprinting technique and freezing/thawing preparation method. The resulted imprinted macroporous monolithic columns were evaluated by utilizing as stationary phase in high performance liquid chromatography and solid-phase extraction materials. The experimental results indicated that the imprinted macroporous monolithic column exhibited good recognition for template protein, as compared with the control protein (hemoglobin), whereas the non-imprinted polymer (prepared under the same conditions except without addition template protein) had no selective properties.

  6. A Possible Astronomically Aligned Monolith at Gardom's Edge

    Science.gov (United States)

    Brown, Daniel; Alder, Andy; Bemand, Elizabeth

    2015-05-01

    A unique triangular shaped monolith located within the Peak District National Park at Gardom's Edge could be intentionally astronomically aligned. It is set within a landscape rich in late Neolithic and Bronze Age remains. We show that the stone is most likely in its original orientation owing to its clear signs of erosion and associated to the time period of the late Neolithic. It is tilted towards south and its north side slopes at an angle equal to the maximum altitude of the Sun at mid-summer. This alignment emphasizes the changing declinations of the Sun during the seasons as well as giving an indication of mid-summers day. This functionality is achieved by an impressive display of light and shadow on the north facing side of the monolith. Together with other monuments in the close vicinity the monolith would have represented an ideal marker or social arena for seasonal gatherings for the otherwise dispersed small communities.

  7. Preliminary shielding analysis for the CSNS target station monolith

    Institute of Scientific and Technical Information of China (English)

    张斌; 陈义学; 杨寿海; 吴军; 殷雯; 梁天骄; 贾学军

    2010-01-01

    The construction of the China Spallation Neutron Source (CSNS) has been initiated at Dongguan,Guangdong,China.In spallation neutron sources the target station monolith is contaminated by a large number of fast neutrons whose energies can be as large as those of the protons of the proton beam directed towards the tungsten target.A detailed radiation transport analysis of the target station monolith is important for the construction of the CSNS.The analysis is performed using the coupled Monte Carlo and multi-dimensional discrete ordinates method.Successful elimination of the primary ray effects via the two-dimensional uncollided flux and first collision source methodology is also illustrated.The dose at the edge of the monolith is calculated.The results demonstrate that the doses received by the hall staff members are below the required standard limit.

  8. Monolithic fuel cell based power source for burst power generation

    Science.gov (United States)

    Fee, D. C.; Blackburn, P. E.; Busch, D. E.; Dees, D. W.; Dusek, J.; Easler, T. E.; Ellingson, W. A.; Flandermeyer, B. K.; Fousek, R. J.; Heiberger, J. J.

    A unique fuel cell coupled with a low power nuclear reactor presents an attractive approach for SDI burst power requirements. The monolithic fuel cell looks attractive for space applications and represents a quantum jump in fuel cell technology. Such a breakthrough in design is the enabling technology for lightweight, low volume power sources for space based pulse power systems. The monolith is unique among fuel cells in being an all solid state device. The capability for miniaturization, inherent in solid state devices, gives the low volume required for space missions. In addition, the solid oxide fuel cell technology employed in the monolith has high temperature reject heat and can be operated in either closed or open cycles. Both these features are attractive for integration into a burst power system.

  9. A Possible Astronomically Aligned Monolith at Gardom's Edge

    CERN Document Server

    Brown, D; Bemand, E

    2012-01-01

    A unique triangular shaped monolith located within the Peak District National Park at Gardom's Edge could be intentionally astronomically aligned. It is set within a landscape rich in late Neolithic and Bronze Age remains. We show that the stone is most likely in its original orientation owing to its clear signs of erosion and associated to the time period of the late Neolithic. It is tilted towards South and its North side slopes at an angle equal to the maximum altitude of the Sun at mid-summer. This alignment emphasizes the changing declinations of the Sun during the seasons as well as giving an indication of mid-summers day. This functionality is achieved by an impressive display of light and shadow on the North-facing side of the Monolith. Together with other monuments in the close vicinity the monolith would have represented an ideal marker or social arena for seasonal gatherings for the else dispersed small communities.

  10. MONOLITHIC FUEL FABRICATION PROCESS DEVELOPMENT AT THE IDAHO NATIONAL LABORATORY_

    Energy Technology Data Exchange (ETDEWEB)

    G. A. Moore; F. J. Rice; N. E. Woolstenhulme; J-F. Jue; B. H. Park; S. E. Steffler; N. P. Hallinan; M. D. Chapple; M. C. Marshall; B. L. Mackowiak; C. R. Clark; B. H. Rabin

    2009-11-01

    Full-size/prototypic U10Mo monolithic fuel-foils and aluminum clad fuel plates are being developed at the Idaho National Laboratory’s (INL) Materials and Fuels Complex (MFC). These efforts are focused on realizing Low Enriched Uranium (LEU) high density monolithic fuel plates for use in High Performance Research and Test Reactors. The U10Mo fuel foils under development afford a fuel meat density of ~16 gU/cc and thus have the potential to facilitate LEU conversions without any significant reactor-performance penalty. An overview is provided of the ongoing monolithic UMo fuel development effort, including application of a zirconium barrier layer on fuel foils, fabrication scale-up efforts, and development of complex/graded fuel foils. Fuel plate clad bonding processes to be discussed include: Hot Isostatic Pressing (HIP) and Friction Bonding (FB).

  11. Pet food recalls and pet food contaminants in small animals.

    Science.gov (United States)

    Bischoff, Karyn; Rumbeiha, Wilson K

    2012-03-01

    Most pet foods are safe, but incidents of chemical contamination occur and lead to illness and recalls. There were 11 major pet food recalls in the United States between 1996 and 2010 that were due to chemical contaminants or misformulations: 3 aflatoxin, 3 excess vitamin D3, 1 excess methionine, 3 inadequate thiamine, and 1 adulteration with melamine and related compounds and an additional 2 warnings concerning a Fanconilike renal syndrome in dogs after ingesting large amounts of chicken jerky treat products. This article describes clinical findings and treatment of animals exposed to the most common pet food contaminants.

  12. Evaluation of resistive-plate-chamber-based TOF-PET applied to in-beam particle therapy monitoring

    Science.gov (United States)

    Torres-Espallardo, I.; Diblen, F.; Rohling, H.; Solevi, P.; Gillam, J.; Watts, D.; España, S.; Vandenberghe, S.; Fiedler, F.; Rafecas, M.

    2015-05-01

    Particle therapy is a highly conformal radiotherapy technique which reduces the dose deposited to the surrounding normal tissues. In order to fully exploit its advantages, treatment monitoring is necessary to minimize uncertainties related to the dose delivery. Up to now, the only clinically feasible technique for the monitoring of therapeutic irradiation with particle beams is Positron Emission Tomography (PET). In this work we have compared a Resistive Plate Chamber (RPC)-based PET scanner with a scintillation-crystal-based PET scanner for this application. In general, the main advantages of the RPC-PET system are its excellent timing resolution, low cost, and the possibility of building large area systems. We simulated a partial-ring scanner based on an RPC prototype under construction within the Fondazione per Adroterapia Oncologica (TERA). For comparison with the crystal-based PET scanner we have chosen the geometry of a commercially available PET scanner, the Philips Gemini TF. The coincidence time resolution used in the simulations takes into account the current achievable values as well as expected improvements of both technologies. Several scenarios (including patient data) have been simulated to evaluate the performance of different scanners. Initial results have shown that the low sensitivity of the RPC hampers its application to hadron-beam monitoring, which has an intrinsically low positron yield compared to diagnostic PET. In addition, for in-beam PET there is a further data loss due to the partial ring configuration. In order to improve the performance of the RPC-based scanner, an improved version of the RPC detector (modifying the thickness of the gas and glass layers), providing a larger sensitivity, has been simulated and compared with an axially extended version of the crystal-based device. The improved version of the RPC shows better performance than the prototype, but the extended version of the crystal-based PET outperforms all other options.

  13. PET-Based Thoracic Radiation Oncology.

    Science.gov (United States)

    Simone, Charles B; Houshmand, Sina; Kalbasi, Anusha; Salavati, Ali; Alavi, Abass

    2016-07-01

    Fluorodeoxyglucose-PET is increasingly being integrated into multiple aspects of oncology. PET/computed tomography (PET/CT) has become especially important in radiation oncology. With the increasing use of advanced techniques like intensity-modulated radiation therapy and proton therapy, PET/CT scans have played critical roles in the target delineation of tumors for radiation oncologists delivering conformal treatment techniques. Use of PET/CT is well established in lung cancer and several other thoracic malignancies. This article details the current uses of PET/CT in thoracic radiation oncology with a focus on lung cancer and describes expected future roles of PET/CT for thoracic tumors.

  14. Preparation of poly(γ-glutamic acid)/hydroxyapatite monolith via biomineralization for bone tissue engineering.

    Science.gov (United States)

    Park, Sung-Bin; Hasegawa, Urara; van der Vlies, André J; Sung, Moon-Hee; Uyama, Hiroshi

    2014-01-01

    A hybrid monolith of poly(γ-glutamic acid) and hydroxyapatite (PGA/HAp monolith) was prepared via biomineralization and used as a macroporous cell scaffold in bone tissue engineering. The PGA monolith having a bimodal pore size distribution was used as a substrate to induce biomineralization. The PGA/HAp monolith was obtained by immersing the PGA monolith in simulated body fluid. Pretreatment with CaCl2 enhanced the apatite-forming ability of the PGA monolith. Murine osteoblastic MC3T3-E1 cells efficiently attached and proliferated on the PGA/HAp monolith. MTT assay showed that both the PGA and PGA/HAp monolith did not have apparent cytotoxicity. Moreover, the PGA and PGA/HAp monoliths adsorbed bone morphogenetic protein-2 (BMP-2) by electrostatic interaction which was slowly released in the medium during cell culture. The PGA/HAp monolith enhanced BMP-2 induced alkaline phosphatase activity compared to the PGA monolith and a polystyrene culture plate. Thus, these PGA/HAp monoliths may have potential in bone tissue engineering.

  15. Numerical Simulation of Fluid Dynamics in a Monolithic Column

    Directory of Open Access Journals (Sweden)

    Kazuhiro Yamamoto

    2017-01-01

    Full Text Available As for the measurement of polycyclic aromatic hydrocarbons (PAHs, ultra-performance liquid chromatography (UPLC is used for PAH identification and densitometry. However, when a solvent containing a substance to be identified passes through a column of UPLC, a dedicated high-pressure-proof device is required. Recently, a liquid chromatography instrument using a monolithic column technology has been proposed to reduce the pressure of UPLC. The present study tested five types of monolithic columns produced in experiments. To simulate the flow field, the lattice Boltzmann method (LBM was used. The velocity profile was discussed to decrease the pressure drop in the ultra-performance liquid chromatography (UPLC system.

  16. A Monolithic Oxide-Based Transversal Thermoelectric Energy Harvester

    Science.gov (United States)

    Teichert, S.; Bochmann, A.; Reimann, T.; Schulz, T.; Dreßler, C.; Udich, S.; Töpfer, J.

    2016-03-01

    We report the fabrication and properties of a monolithic transversal thermoelectric energy harvester based on the combination of a thermoelectric oxide and a metal. The fabrication of the device is done with a ceramic multilayer technology using printing and co-firing processes. Five transversal devices were combined to a meander-like thermoelectric generator. Electrical measurements and finite element calculations were performed to characterize the resulting thermoelectric generator. A maximum experimental electrical power output of 30.2 mW at a temperature difference of {Δ }T = 208 K was found. The prepared monolithic thermoelectric generator provides at {Δ }T = 35 K sufficient energy to drive a simple electronic sensor application.

  17. Monolithic Michelson Interferometer as ultra stable wavelength reference

    Science.gov (United States)

    Wan, Xiaoke; Ge, Jian

    2010-07-01

    Ultra-stable Monolithic Michelson interferometer can be an ideal reference for highprecision applications such as RV measurement in planet searching and orbit study. The advantages include wide wavelength range, simple sinusoidal spectral format, and high optical efficiency. In this paper, we report that a monolithic Michelson interferometers has been in-house developed with minimized thermal sensitivity with compensation tuning. With a scanning white light interferometer, the thermal sensitivity is measured ~ 6x10-7/°C at 550 nm and it decreases to zero near 1000 nm. We expect the wideband wavelength reference source to be stabilized better than 0.3 m/s for RV experiments

  18. Lectin-carbohydrate interactions on nanoporous gold monoliths.

    Science.gov (United States)

    Tan, Yih Horng; Fujikawa, Kohki; Pornsuriyasak, Papapida; Alla, Allan J; Ganesh, N Vijaya; Demchenko, Alexei V; Stine, Keith J

    2013-07-01

    Monoliths of nanoporous gold (np-Au) were modified with self-assembled monolayers of octadecanethiol (C18-SH), 8-mercaptooctyl α-D-mannopyranoside (αMan-C8-SH), and 8-mercapto-3,6-dioxaoctanol (HO-PEG2-SH), and the loading was assessed using thermogravimetric analysis (TGA). Modification with mixed SAMs containing αMan-C8-SH (at a 0.20 mole fraction in the SAM forming solution) with either octanethiol or HO-PEG2-SH was also investigated. The np-Au monoliths modified with αMan-C8-SH bind the lectin Concanavalin A (Con A), and the additional mass due to bound protein was assessed using TGA analysis. A comparison of TGA traces measured before and after exposure of HO-PEG2-SH modified np-Au to Con A showed that the non-specific binding of Con A was minimal. In contrast, np-Au modified with octanethiol showed a significant mass loss due to non-specifically adsorbed Con A. A significant mass loss was also attributed to binding of Con A to bare np-Au monoliths. TGA revealed a mass loss due to the binding of Con A to np-Au monoliths modified with pure αMan-C8-SH. The use of mass losses determined by TGA to compare the binding of Con A to np-Au monoliths modified by mixed SAMs of αMan-C8-SH and either octanethiol or HO-PEG2-SH revealed that binding to mixed SAM modified surfaces is specific for the mixed SAMs with HO-PEG2-SH but shows a significant contribution from non-specific adsorption for the mixed SAMs with octanethiol. Minimal adsorption of immunoglobulin G (IgG) and peanut agglutinin (PNA) towards the mannoside modified np-Au monoliths was demonstrated. A greater mass loss was found for Con A bound onto the monolith than for either IgG or PNA, signifying that the mannose presenting SAMs in np-Au retain selectivity for Con A. TGA data also provide evidence that Con A bound to the αMan-C8-SH modified np-Au can be eluted by flowing a solution of methyl α-D-mannopyranoside through the structure. The presence of Con A proteins on the modified np-Au surface was

  19. Paladin Enterprises: Monolithic particle physics models global climate.

    CERN Multimedia

    2002-01-01

    Paladin Enterprises presents a monolithic particle model of the universe which will be used by them to build an economical fusion energy system. The model is an extension of the work done by James Clerk Maxwell. Essentially, gravity is unified with electro-magnetic forces and shown to be a product of a closed loop current system, i.e. a particle - monolithic or sub atomic. This discovery explains rapid global climate changes which are evident in the geological record and also provides an explanation for recent changes in the global climate.

  20. Investigation of spatial resolution improvement by use of a mouth-insert detector in the helmet PET scanner.

    Science.gov (United States)

    Ahmed, Abdella M; Tashima, Hideaki; Yamaya, Taiga

    2017-10-06

    The dominant factor limiting the intrinsic spatial resolution of a positron emission tomography (PET) system is the size of the crystal elements in the detector. To increase sensitivity and achieve high spatial resolution, it is essential to use advanced depth-of-interaction (DOI) detectors and arrange them close to the subject. The DOI detectors help maintain high spatial resolution by mitigating the parallax error caused by the thickness of the scintillator near the peripheral regions of the field-of-view. As an optimal geometry for a brain PET scanner, with high sensitivity and spatial resolution, we proposed and developed the helmet-chin PET scanner using 54 four-layered DOI detectors consisting of a 16 × 16 × 4 array of GSOZ scintillator crystals with dimensions of 2.8 × 2.8 × 7.5 mm(3). All the detectors used in the helmet-chin PET scanner had the same spatial resolution. In this study, we conducted a feasibility study of a new add-on detector arrangement for the helmet PET scanner by replacing the chin detector with a segmented crystal cube, having high spatial resolution in all directions, which can be placed inside the mouth. The crystal cube (which we have named the mouth-insert detector) has an array of 20 × 20 × 20 LYSO crystal segments with dimensions of 1 × 1 × 1 mm(3). Thus, the scanner is formed by the combination of the helmet and mouth-insert detectors, and is referred to as the helmet-mouth-insert PET scanner. The results show that the helmet-mouth-insert PET scanner has comparable sensitivity and improved spatial resolution near the center of the hemisphere, compared to the helmet-chin PET scanner.

  1. Characterization of the Ferrara animal PET scanner

    CERN Document Server

    Di Domenico, G; Damiani, C; Del Guerra, A; Gilardi, M C; Motta, A; Zavattini, G

    2002-01-01

    A dedicated small animal PET scanner, YAPPET, was designed and built at Ferrara University. Each detector consists of a 20x20 matrix of 2x2x30 mm sup 3 YAP:Ce finger-like crystals glued together and directly coupled to a Hamamatsu position sensitive photomultiplier. The scanner is made from four detectors positioned on a rotating gantry at a distance of 7.5 cm from the center and the field of view (FOV) is 4 cm both in the transaxial direction and in the axial direction. The system operates in 3D acquisition mode. The performance parameters of YAPPET scanner such as spatial, energy and time resolution, as well as its sensitivity and counting rate have been determined. The average spatial resolution over the whole FOV is 1.8 mm at FWHM and 4.2 mm at FWTM. The sensitivity at the center is 640 cps/mu Ci.

  2. Phase Field Modeling Using PetIGA

    KAUST Repository

    Vignal, Philippe A.

    2013-06-01

    Phase field modeling has become a widely used framework in the computational material science community. Its ability to model different problems by defining appropriate phase field parameters and relating it to a free energy functional makes it highly versatile. Thermodynamically consistent partial differential equations can then be generated by assuming dissipative dynamics, and setting up the problem as one of minimizing this free energy. The equations are nonetheless challenging to solve, and having a highly efficient and parallel framework to solve them is necessary. In this work, a brief review on phase field models is given, followed by a short analysis of the Phase Field Crystal Model solved with Isogeometric Analysis us- ing PetIGA. We end with an introduction to a new modeling concept, where free energy functions are built with a periodic equilibrium structure in mind.

  3. Polyurea-Based Aerogel Monoliths and Composites

    Science.gov (United States)

    Lee, Je Kyun

    2012-01-01

    aerogel insulation material was developed that will provide superior thermal insulation and inherent radiation protection for government and commercial applications. The rubbery polyureabased aerogel exhibits little dustiness, good flexibility and toughness, and durability typical of the parent polyurea polymer, yet with the low density and superior insulation properties associated with aerogels. The thermal conductivity values of polyurea-based aerogels at lower temperature under vacuum pressures are very low and better than that of silica aerogels. Flexible, rubbery polyurea-based aerogels are able to overcome the weak and brittle nature of conventional inorganic and organic aerogels, including polyisocyanurate aerogels, which are generally prepared with the one similar component to polyurethane rubber aerogels. Additionally, with higher content of hydrogen in their structures, the polyurea rubber-based aerogels will also provide inherently better radiation protection than those of inorganic and carbon aerogels. The aerogel materials also demonstrate good hydrophobicity due to their hydrocarbon molecular structure. There are several strategies to overcoming the drawbacks associated with the weakness and brittleness of silica aerogels. Development of the flexible fiber-reinforced silica aerogel composite blanket has proven to be one promising approach, providing a conveniently fielded form factor that is relatively robust in industrial environments compared to silica aerogel monoliths. However, the flexible, silica aerogel composites still have a brittle, dusty character that may be undesirable, or even intolerable, in certain application environments. Although the cross - linked organic aerogels, such as resorcinol- formaldehyde (RF), polyisocyanurate, and cellulose aerogels, show very high impact strength, they are also very brittle with little elongation (i.e., less rubbery). Also, silica and carbon aerogels are less efficient radiation shielding materials due

  4. Constitutive Theory Developed for Monolithic Ceramic Materials

    Science.gov (United States)

    Janosik, Lesley A.

    1998-01-01

    with these service conditions by developing a multiaxial viscoplastic constitutive model that accounts for time-dependent hereditary material deformation (such as creep and stress relaxation) in monolithic structural ceramics. Using continuum principles of engineering mechanics, we derived the complete viscoplastic theory from a scalar dissipative potential function.

  5. Monolithic, High-Speed Fiber-Optic Switching Array for Lidar

    Science.gov (United States)

    Suckow, Will; Roberts, Tony; Switzer, Gregg; Terwilliger, Chelle

    2011-01-01

    Current fiber switch technologies use mechanical means to redirect light beams, resulting in slow switch time, as well as poor reliability due to moving parts wearing out quickly at high speeds. A non-mechanical ability to switch laser output into one of multiple fibers within a fiber array can provide significant power, weight, and costs savings to an all-fiber system. This invention uses an array of crystals that act as miniature prisms to redirect light as an electric voltage changes the prism s properties. At the heart of the electro-optic fiber-optic switch is an electro- optic crystal patterned with tiny prisms that can deflect the beam from the input fiber into any one of the receiving fibers arranged in a linear array when a voltage is applied across the crystal. Prism boundaries are defined by a net dipole moment in the crystal lattice that has been poled opposite to the surrounding lattice fabricated using patterned, removable microelectrodes. When a voltage is applied across the crystal, the resulting electric field changes the index of refraction within the prism boundaries relative to the surrounding substrate, causing light to deflect slightly according to Snell s Law. There are several materials that can host the necessary monolithic poled pattern (including, but not limited to, SLT, KTP, LiNbO3, and Mg:LiNbO3). Be cause this is a solid-state system without moving parts, it is very fast, and does not wear down easily. This invention is applicable to all fiber networks, as well as industries that use such networks. The unit comes in a compact package, can handle both low and high voltages, and has a high reliability (100,000 hours without maintenance).

  6. PET/TAC in Oncology; PET/TAC en Oncologia

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez V, A.M. [Especialista en Medicina Nuclear, Profa. Depto. Radiologia de la Facultad de Medicina, Universidad Complutense de Madrid, Madrid (Spain)

    2007-07-01

    From this presentation of PET-TAC in oncology the following advantages on the conventional PET are obtained: 1. More short study and stadium in one session. 2. It adds the information of both techniques. 3. Better localization of leisure: affected organ, stadium change (neck, mediastinum, abdomen). 4. Reduction of false positive (muscle, brown fat, atelectasis, pneumonias, intestine, urinary vials, etc.). 5. Reduction of negative false. 6. Reduction of not conclusive. 7. More understandable for other specialists. 8. Biopsies guide. 9. Planning radiotherapy.

  7. Chromatographic comparison of bupivacaine imprinted polymers prepared in crushed monolith, microsphere, silica-based composite and capillary monolith formats.

    Science.gov (United States)

    Oxelbark, Joakim; Legido-Quigley, Cristina; Aureliano, Carla S A; Titirici, Maria-Magdalena; Schillinger, Eric; Sellergren, Börje; Courtois, Julien; Irgum, Knut; Dambies, Laurent; Cormack, Peter A G; Sherrington, David C; De Lorenzi, Ersilia

    2007-08-10

    A comprehensive comparison of five chromatographic stationary phases based on molecularly imprinted polymers is presented. Efficiency, imprinting factors, water compatibility and batch-to-batch reproducibility are discussed for crushed monolith, microspheres, two silica-based composites and capillary monoliths, all imprinted with the local anaesthetic bupivacaine. Synthesis protocol and chromatographic test conditions have been kept fixed within certain limits, in order to provide further insight into the strengths and weaknesses of the different formats. Excluding microparticles, all formats give satisfactory performance, especially in aqueous mobile phases. An assessment of batch-to-batch reproducibility in different mobile phases adds further value to this comparison study.

  8. Veterinarians' role for pet owners facing pet loss.

    Science.gov (United States)

    Fernandez-Mehler, P; Gloor, P; Sager, E; Lewis, F I; Glaus, T M

    2013-05-25

    Owners' satisfaction with, and expectations from, their veterinarians around euthanasia, including questions on disposal of pet remains subject to animal species, clients' gender, age, family conditions, area of living and type of veterinary clinic visited were evaluated by questionnaire. Questionnaires were to be filled out by clients consecutively visiting the individual practices and hospitals for any kind of consultations. Of 2350 questionnaires distributed, 2008 were returned and available for analysis. Owner satisfaction concerning the procedure of euthanasia was high (92 per cent, 1173/1272). After the event of euthanasia, 14 per cent (170/1250) had changed their veterinarian, even though 75 per cent of these 170 had been satisfied with the procedure. Most owners (88 per cent) expected veterinarians to talk about their pet's final destination, and 38 per cent expected this to happen early in the pet's life. For 81 per cent clients, the veterinarian was the primary informant about the possibilities concerning the disposal of pet remains, and 33 per cent indicated their veterinarian as the contact person to talk about pet loss. Area of living, or veterinary specialisation, only marginally influenced the answers. Veterinarians play an important role to inform their clients concerning questions around euthanasia and the care of pet remains, and to support them during the process of mourning.

  9. Lanthanum halide scintillators for time-of-flight 3-D pet

    Science.gov (United States)

    Karp, Joel S.; Surti, Suleman

    2008-06-03

    A Lanthanum Halide scintillator (for example LaCl.sub.3 and LaBr.sub.3) with fast decay time and good timing resolution, as well as high light output and good energy resolution, is used in the design of a PET scanner. The PET scanner includes a cavity for accepting a patient and a plurality of PET detector modules arranged in an approximately cylindrical configuration about the cavity. Each PET detector includes a Lanthanum Halide scintillator having a plurality of Lanthanum Halide crystals, a light guide, and a plurality of photomultiplier tubes arranged respectively peripherally around the cavity. The good timing resolution enables a time-of-flight (TOF) PET scanner to be developed that exhibits a reduction in noise propagation during image reconstruction and a gain in the signal-to-noise ratio. Such a PET scanner includes a time stamp circuit that records the time of receipt of gamma rays by respective PET detectors and provides timing data outputs that are provided to a processor that, in turn, calculates time-of-flight (TOF) of gamma rays through a patient in the cavity and uses the TOF of gamma rays in the reconstruction of images of the patient.

  10. Development of a SiPM-based PET imaging system for small animals

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yanye [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Yang, Kun, E-mail: yangkun9999@hotmail.com [Department of Control Technology and Instrumentation, College of Quality and Technical Supervision, Hebei University, Baoding, 071000 (China); Zhou, Kedi; Zhang, Qiushi; Pang, Bo [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Ren, Qiushi, E-mail: renqsh@coe.pku.edu.cn [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China)

    2014-04-11

    Advances in small animal positron emission tomography (PET) imaging have been accelerated by many new technologies such as the successful incorporation of silicon photomultiplier (SiPM). In this paper, we have developed a compact, lightweight PET imaging system that is based on SiPM detectors for small animals imaging, which could be integrated into a multi-modality imaging system. This PET imaging system consists of a stationary detector gantry, a motor-controlled animal bed module, electronics modules, and power supply modules. The PET detector, which was designed as a multi-slice circular ring geometry of 27 discrete block detectors, is composed of a cerium doped lutetium–yttrium oxyorthosilicate (LYSO) scintillation crystal and SiPM arrays. The system has a 60 mm transaxial field of view (FOV) and a 26 mm axial FOV. Performance tests (e.g. spatial resolution, energy resolution, and sensitivity) and phantom and animal imaging studies were performed to evaluate the imaging performance of the PET imaging system. The performance tests and animal imaging results demonstrate the feasibility of an animal PET system based on SiPM detectors and indicate that SiPM detectors can be promising photodetectors in animal PET instrumentation development.

  11. Application of a low impedance contactless conductometric detector for the determination of inorganic cations in capillary monolithic column chromatography.

    Science.gov (United States)

    Shen, Dazhong; Li, Dongdong; Yang, Xiuwen; Zhu, Yan; Dong, Jianfeng; Kang, Qi

    2011-03-15

    Poly(glycidyl methacrylate) cation exchange monolithic column was prepared in fused-silica capillaries of 320 μm i.d. by thermally initiated radical polymerization and utilized in capillary ion chromatography. With 15 mM methanesulfonic acid as the mobile phase, the separations of a mixture of inorganic cations (Li(+), Na(+), NH(4)(+), K(+)) was tested by using a capacitively coupled contactless conductivity detector (C(4)D) and a low impedance C(4)D (LIC(4)D). The LIC(4)D is the series combination of a C(4)D and a quartz crystal resonator. At the resonant frequency of the series combination, the capacitor impedance from capillary wall was offset by the inductance impedance from the quartz crystal resonator. A minimum impedance was obtained in the impedance-frequency curve of the combination. The responses of the C(4)D and LIC(4)D were analyzed based on an equivalent circuit model. It was shown that the sensitivity of the C(4)D to the change in analyte concentration is rather poor due to the high ratio of the impedance from the capillary wall capacitor to the solution impedance. The LIC(4)D has the similar sensitivity as a contact conductivity detector but a much smaller cell volume. The on-column detection model was realized by LiC(4)D without preparation of optical detection window in monolithic column.

  12. STUDY ON THE EFFECTS OF TLCP ON PYROLYSIS OF PET AND ITS RETARDANT MECHANISM

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The flame retardancy of aromatic thermotropic liquid crystal phosphorus-containing copolyester,TLCP,on PET was investigated.The results show that the presence of TLCP promotes char formation of the substrate and enhances thermal stability of char,hence delay its decomposition.SEM pictures show that the char formed from PET/TLCP is more compact,therefore is more resistant to fire and heat than that from pure PET.Evolved gas analysis by I.R measurements indicates that TLCP would decompose to produce phosphorus containing small molecular compounds in pyrolysis process.Phosphoruscontaining volatile compounds are detected in gas pyrolytical products.It is suggested that TLCP could play an important role of flame retardancy in vapor phase.TLCP could inhibit the generation of combustible volatile in the pyrolytical process of PET,and therefore prevent the fire propagation during the combustion since combustible volatile is necessary for the generation of fire.

  13. Image reconstruction for AX-PET. Different approaches to histograming for semi-continuous data

    Energy Technology Data Exchange (ETDEWEB)

    Solevi, P.; Oliver, J.F.; Gillam, J. [Council for Scientific Research (CSIC)/Valencia Univ. (Spain). IFIC; Rafecas, M. [Valencia Univ. (Spain). Dept. of Atomic, Molecular, and Nuclear Physics

    2011-07-01

    AX-PET is a unique PET device based on axially oriented crystals and orthogonally placed Wavelength shifter strips, both individually readout by Geiger-mode Avalanche Photo Diodes (G-APD, also known as SiPM). The AX-PET design was conceived in order to simultaneously improve spatial resolution and sensitivity by reducing the parallax error. The peculiar design of AX-PET yields discrete transaxial and depth (x and y) coordinates, while the axial coordinate is continuous. In order not to lose resolution, various approaches to treat the axial coordinate were explored to deal with the semi-continuous coordinates. A data set suitable for this task was processed and reconstructed by using different techniques, and the results are presented. This new approach better model the z pdf but, depending on the used technique to estimate the weight, might introduce some blurring in the final image. (orig.)

  14. Influence of expanded graphite (EG and graphene oxide (GO on physical properties of PET based nanocomposites

    Directory of Open Access Journals (Sweden)

    Paszkiewicz Sandra

    2014-12-01

    Full Text Available This work is the continuation and refinement of already published communications based on PET/EG nanocomposites prepared by in situ polymerization1, 2. In this study, nanocomposites based on poly(ethylene terephthalate with expanded graphite were compared to those with functionalized graphite sheets (GO. The results suggest that the degree of dispersion of nanoparticles in the PET matrix has important effect on the structure and physical properties of the nanocomposites. The existence of graphene sheets nanoparticles enhances the crystallization rate of PET. It has been confirmed that in situ polymerization is the effective method for preparation nanocomposites which can avoid the agglomeration of nanoparticles in polymer matrices and improve the interfacial interaction between nanofiller and polymer matrix. The obtained results have shown also that due to the presence of functional groups on GO surface the interactions with PET matrix can be stronger than in the case of exfoliated graphene (EG and matrix.

  15. MR-compatibility of a high-resolution small animal PET insert operating inside a 7 T MRI

    Science.gov (United States)

    Thiessen, J. D.; Shams, E.; Stortz, G.; Schellenberg, G.; Bishop, D.; Khan, M. S.; Kozlowski, P.; Retière, F.; Sossi, V.; Thompson, C. J.; Goertzen, A. L.

    2016-11-01

    A full-ring PET insert consisting of 16 PET detector modules was designed and constructed to fit within the 114 mm diameter gradient bore of a Bruker 7 T MRI. The individual detector modules contain two silicon photomultiplier (SiPM) arrays, dual-layer offset LYSO crystal arrays, and high-definition multimedia interface (HDMI) cables for both signal and power transmission. Several different RF shielding configurations were assessed prior to construction of a fully assembled PET insert using a combination of carbon fibre and copper foil for RF shielding. MR-compatibility measurements included field mapping of the static magnetic field (B 0) and the time-varying excitation field (B 1) as well as acquisitions with multiple pulse sequences: spin echo (SE), rapid imaging with refocused echoes (RARE), fast low angle shot (FLASH) gradient echo, and echo planar imaging (EPI). B 0 field maps revealed a small degradation in the mean homogeneity (+0.1 ppm) when the PET insert was installed and operating. No significant change was observed in the B 1 field maps or the image homogeneity of various MR images, with a 9% decrease in the signal-to-noise ratio (SNR) observed only in EPI images acquired with the PET insert installed and operating. PET detector flood histograms, photopeak amplitudes, and energy resolutions were unchanged in individual PET detector modules when acquired during MRI operation. There was a small baseline shift on the PET detector signals due to the switching amplifiers used to power MRI gradient pulses. This baseline shift was observable when measured with an oscilloscope and varied as a function of the gradient duty cycle, but had no noticeable effect on the performance of the PET detector modules. Compact front-end electronics and effective RF shielding led to minimal cross-interference between the PET and MRI systems. Both PET detector and MRI performance was excellent, whether operating as a standalone system or a hybrid PET/MRI.

  16. Take Care with Pet Reptiles

    Science.gov (United States)

    ... Past Emails CDC Features Take Care with Pet Reptiles and Amphibians Language: English Español (Spanish) Recommend on ... messages, and helpful resources. Safe Handling Tips for Reptiles and Amphibians Always wash your hands thoroughly after ...

  17. PET and PET/CT in tumour of undetermined origin; PET y PET/CT en tumor de origen indeterminado

    Energy Technology Data Exchange (ETDEWEB)

    Garcia O, J.R. [Nuclear Medicine and Molecular Imaging, PET/CT, Centro Medico ABC, Mexico D.F. (Mexico)

    2007-07-01

    In this presentation the following conclusions were obtained regarding the use of PET and PET/CT in patient with cancer of unknown primary: 1. Detection of the primary one in 1/3 at 1/2 of patient. 2. It detects metastases in other places in 50%. 3. It changes the initial therapy planned in 1/3 at 1/2 of patient. 4. Useful in initial phases of protocol study to limit the other procedures. After standard evaluation. Before advanced protocol. 5. PET/CT study increases the % of primary detection, although in a non significant way vs. PET. 6. They are required more studies to value their utility to a more objective manner. (Author)

  18. Performance modeling of a wearable brain PET (BET) camera

    Science.gov (United States)

    Schmidtlein, C. R.; Turner, J. N.; Thompson, M. O.; Mandal, K. C.; Häggström, I.; Zhang, J.; Humm, J. L.; Feiglin, D. H.; Krol, A.

    2016-03-01

    Purpose: To explore, by means of analytical and Monte Carlo modeling, performance of a novel lightweight and low-cost wearable helmet-shaped Brain PET (BET) camera based on thin-film digital Geiger Avalanche Photo Diode (dGAPD) with LSO and LaBr3 scintillators for imaging in vivo human brain processes for freely moving and acting subjects responding to various stimuli in any environment. Methods: We performed analytical and Monte Carlo modeling PET performance of a spherical cap BET device and cylindrical brain PET (CYL) device, both with 25 cm diameter and the same total mass of LSO scintillator. Total mass of LSO in both the BET and CYL systems is about 32 kg for a 25 mm thick scintillator, and 13 kg for 10 mm thick scintillator (assuming an LSO density of 7.3 g/ml). We also investigated a similar system using an LaBr3 scintillator corresponding to 22 kg and 9 kg for the 25 mm and 10 mm thick systems (assuming an LaBr3 density of 5.08 g/ml). In addition, we considered a clinical whole body (WB) LSO PET/CT scanner with 82 cm ring diameter and 15.8 cm axial length to represent a reference system. BET consisted of distributed Autonomous Detector Arrays (ADAs) integrated into Intelligent Autonomous Detector Blocks (IADBs). The ADA comprised of an array of small LYSO scintillator volumes (voxels with base a×a: 1.0 50% better noise equivalent count (NEC) performance relative to the CYL geometry, and >1100% better performance than a WB geometry for 25 mm thick LSO and LaBr3. For 10 mm thick LaBr3 equivalent mass systems LSO (7 mm thick) performed ~40% higher NEC than LaBr3. Analytic and Monte Carlo simulations also showed that 1×1×3 mm scintillator crystals can achieve ~1.2 mm FWHM spatial resolution. Conclusions: This study shows that a spherical cap brain PET system can provide improved NEC while preserving spatial resolution when compared to an equivalent dedicated cylindrical PET brain camera and shows greatly improved PET performance relative to a conventional

  19. Performance of a PET Insert for High Resolution Small Animal PET/MR Imaging at 7T.

    Science.gov (United States)

    Stortz, Greg; Thiessen, Jonathan D; Bishop, Daryl; Khan, Muhammad S; Kozlowski, Piotr; Retière, Fabrice; Schellenberg, Graham; Shams, Ehsan; Zhang, Xuezhu; Thompson, Christopher J; Goertzen, Andrew; Sossi, Vesna

    2017-09-14

    We present the characterization of a compact magnetic resonance (MR) compatible positron emission tomography (PET) insert for simultaneous pre-clinical PET/MR imaging. While specifically designed with the strict size constraint to fit inside the 114 mm inner diameter of the BGA-12S gradient coil used in the Bruker 70/20 and 94/20 series of small animal MR imaging (MRI) systems, the insert can be easily installed in any appropriate MRI scanner or used as a stand-alone PET system. Methods: The insert is made from a ring of 16 detector-blocks each made from depth-of-interaction capable dual-layer-offset arrays of cerium-doped lutetium-yttrium oxyorthosilicate crystals read out by silicon photomultiplier (SiPM) arrays. Scintillator crystal arrays are made from 22×10 / 21×9 crystals in the bottom/top layers with 6/4 mm layer thicknesses, arranged with a 1.27 mm pitch, resulting in a useable field of view (FOV) 28 mm long and ~55 mm wide. Results: Spatial resolution ranges from 1.17 to 1.86 mm full-width-at-half-maximum (FWHM) in the radial direction from a radial offset of 0 to 15 mm. With a 300-800 keV energy window, peak sensitivity is 2.2% and noise-equivalent count rate (NECR) from a mouse-sized phantom at 3.7 MBq is 11.1 kcps and peaks at 20.8 kcps at 14.5 MBq. Phantom imaging shows that feature sizes as low as 0.7 mm can be resolved. (18)F-fluorodeoxyglucose ((18)F-FDG) PET/MR images of mouse and rat brains show no signs of inter-modality interference, and can excellently resolve substructures within the brains. Conclusion: Due to excellent spatial resolvability and lack of intermodality interference, this PET insert will serve as a useful tool for pre-clinical PET/MR. Copyright © 2017 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  20. A radiation hard bipolar monolithic front-end readout

    CERN Document Server

    Baschirotto, A; Cappelluti, I; Castello, R; Cermesoni, M; Gola, A; Pessina, G; Pistolesi, E; Rancoita, P G; Seidman, A

    1999-01-01

    A fast bipolar monolithic charge sensitive preamplifier (CSP), implemented in the monolithic 2 mu m BiCMOS technology (called HF2CMOS) was designed and built in a quad monolithic chip. Studies of radiation effects in the CSP $9 performance, from non-irradiated and up to neutron irradiation of 5.3*10/sup 14/ n/cm/sup 2/, have confirmed that the use of bipolar npn transistors is suitable for the radiation level of the future LHC collider environment. The CSP $9 presents a new circuit solution for obtaining adequate slew rate performances which results in an integral linearity better than 0.8554330n 5 V at 20 ns of shaping time, regardless of the bias current selected for the CSP. This way $9 the bias current of the CSP can be set for optimizing the power dissipation with respect to series and parallel noise, especially useful when the CSP is put in a radiation environment. A prototype test with a novel monolithic 20 ns $9 time constant RC-CR shaper, capable to sum up four inputs has been also realized, featurin...

  1. Carbon monolith: preparation, characterization and application as microextraction fiber.

    Science.gov (United States)

    Shi, Zhi-Guo; Chen, Fei; Xing, Jun; Feng, Yu-Qi

    2009-07-10

    A carbon monolith was synthesized via a polymerization-carbonization method, styrene and divinylbenzene being adopted as precursors and dodecanol as a porogen during polymerization. The resultant monolith had bimodal porous substructure, narrowly distributed nano skeleton pores and uniform textural pores or throughpores. The carbon monolith was directly used as an extracting fiber, taking place of the coated silica fibers in commercially available solid-phase microextraction device, for the extraction of phenols followed by gas chromatography-mass spectrometry. Under the studied conditions, the calibration curves were linear from 0.5 to 50 ng mL(-1) for phenol, o-nitrophenol, 2,4-dichlorophenol and p-chlorophenol. The limits of detection were between 0.04 and 0.43 ng mL(-1). The recoveries of the phenols spiked in real water samples at 10 ng mL(-1) were between 85% and 98% with the relative standard deviations below 10%. Compared with the commercial coated ones (e.g. PDMS, CW/DVB and DVB/CAR/PDMS), the carbon monolith-based fiber had advantages of faster extraction equilibrium and higher extraction capacity due to the superior pore connectivity and pore openness resulting from its bimodal porous substructure.

  2. Shear bond strength of indirect composite material to monolithic zirconia

    Science.gov (United States)

    2016-01-01

    PURPOSE This study aimed to evaluate the effect of surface treatments on bond strength of indirect composite material (Tescera Indirect Composite System) to monolithic zirconia (inCoris TZI). MATERIALS AND METHODS Partially stabilized monolithic zirconia blocks were cut into with 2.0 mm thickness. Sintered zirconia specimens were divided into different surface treatment groups: no treatment (control), sandblasting, glaze layer & hydrofluoric acid application, and sandblasting + glaze layer & hydrofluoric acid application. The indirect composite material was applied to the surface of the monolithic zirconia specimens. Shear bond strength value of each specimen was evaluated after thermocycling. The fractured surface of each specimen was examined with a stereomicroscope and a scanning electron microscope to assess the failure types. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey LSD tests (α=.05). RESULTS Bond strength was significantly lower in untreated specimens than in sandblasted specimens (P<.05). No difference between the glaze layer and hydrofluoric acid application treated groups were observed. However, bond strength for these groups were significantly higher as compared with the other two groups (P<.05). CONCLUSION Combined use of glaze layer & hydrofluoric acid application and silanization are reliable for strong and durable bonding between indirect composite material and monolithic zirconia. PMID:27555895

  3. Cyclodextrin-Functionalized Monolithic Capillary Columns: Preparation and Chiral Applications.

    Science.gov (United States)

    Adly, Frady G; Antwi, Nana Yaa; Ghanem, Ashraf

    2016-02-01

    In this review, the recently reported approaches for the preparation of cyclodextrin-functionalized capillary monolithic columns are highlighted, with few applications in chiral separations using capillary liquid chromatography (CLC) and capillary electrochromatography (CEC). Chirality 28:97-109, 2016. © 2015 Wiley Periodicals, Inc.

  4. Monolithic natural gas storage delivery system based on sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Hornbostel, Marc; Krishnan, Gopala N.; Sanjurjo, Angel

    2016-09-27

    The invention provides methods for producing a strong, light, sorbent-based storage/dispenser system for gases and fuels. The system comprises a porous monolithic material with an adherent strong impervious skin that is capable of storing a gas under pressure in a safe and usable manner.

  5. Monolithic natural gas storage delivery system based on sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Hornbostel, Marc; Krishnan, Gopala N.; Sanjurjo, Angel

    2016-09-27

    The invention provides methods for producing a strong, light, sorbent-based storage/dispenser system for gases and fuels. The system comprises a porous monolithic material with an adherent strong impervious skin that is capable of storing a gas under pressure in a safe and usable manner.

  6. Multiple Quantum Well (MQW) Devices For Monolithic Integrated Optoelectronics

    Science.gov (United States)

    Wood, Thomas H.

    1988-05-01

    Semiconductor MQWs represent a new technology for opto-electronics. These MQWs have an electroabsorption effect approximately 50 times larger than conventional semiconductors. They are compatible with existing source and detector material systems and produce devices that are compact and high speed, which makes them useful for monolithic integrated optoelectronic devices.

  7. Morphosynthesis of cubic silver cages on monolithic activated carbon.

    Science.gov (United States)

    Wang, Fei; Zhao, Hong; Lai, Yijian; Liu, Siyu; Zhao, Binyuan; Ning, Yuesheng; Hu, Xiaobin

    2013-11-14

    Cubic silver cages were prepared on monolithic activated carbon (MAC) pre-absorbed with Cl(-), SO4(2-), or PO4(3-) anions. Silver insoluble salts served as templates for the morphosynthesis of silver cages. The silver ions were reduced by reductive functional groups on MAC micropores through a galvanic cell reaction mechanism.

  8. 3D-Printed MOF Monoliths for Gas Adsorption Processes.

    Science.gov (United States)

    Thakkar, Harshul; Eastman, Stephen; Al-Naddaf, Qasim; Rownaghi, Ali Asghar; Rezaei, Fateme

    2017-09-27

    Metal-Organic Frameworks (MOFs) have shown promising performance in separation, adsorption, reaction and storage of various industrial gases, however, their large-scale applications have been hampered by the lack of a proper strategy to formulate them into scalable gas-solid contactors. Herein, we report fabrication of MOF monoliths using 3D printing technique and evaluation of their adsorptive performance in CO2 removal from air. The 3D-printed MOF-74(Ni) and UTSA-16(Co) monoliths with MOF loadings as high as 80 and 85 wt %, respectively were developed and their physical and structural properties were characterized and compared with those of MOF powders. Our adsorption experiments showed that upon exposure to 5,000 ppm (0.5%) CO2 at 25 ºC, the MOF-74(Ni) and UTSA-16(Co) monoliths can adsorb CO2 with the uptake capacity of 1.35 and 1.31 mmol/g, respectively, which are 79 and 87% of the capacity of their MOF analogues under the same conditions. Furthermore, a stable performance was obtained for self-standing 3D-printed monolithic structures with relatively good adsorption kinetics. The preliminary findings reported in this investigation highlight the advantage of robocasting (3D printing) technique for shaping MOF materials into practical configurations that are suitable for various gas separation applications.

  9. From 1D to 3D - macroscopic nanowire aerogel monoliths.

    Science.gov (United States)

    Cheng, Wei; Rechberger, Felix; Niederberger, Markus

    2016-08-01

    Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying.

  10. KINETICS OF NON-ISOTHERMAL CRYSTALLIZATION OF POLY (ETHYLENE TEREPHTHALATE) MODIFIED BY POLY (ETHYLENE GLYCOL)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhiying; WU Shizhen; DU Yinghua; CAO Zhenlin

    1991-01-01

    The non-isothermal crystallization kinetics of poly(ethylene terephthalate) (PET) modified by poly (ethlene glycol) (PEG) were determined by DSC. The dual linear regression method was used to evaluate the relationship between the reciprocal of t1/2 ( the half life of crystallization ) and the appropriate temperature variable. The parameters such as the activation energy (Ed) for transport,the equilibrium melting temperature (T0m),the nucleation parameter (ψ),the maximum crystallization temperature (Tc, max ) , and the kinetic crystallizability (G) for the copolyesters were obtained. The influence of the PEG content in PET chains on the parameters characterizing crystallization kinetics and crystallization thermodynamics was discussed.

  11. A feasibility study of a prototype PET insert device to convert a general-purpose animal PET scanner to higher resolution.

    Science.gov (United States)

    Wu, Heyu; Pal, Debashish; O'Sullivan, Joseph A; Tai, Yuan-Chuan

    2008-01-01

    We developed a prototype system to evaluate the feasibility of using a PET insert device to achieve higher resolution from a general-purpose animal PET scanner. The system consists of a high-resolution PET detector, a computer-controlled rotation stage, and a custom mounting plate. The detector consists of a cerium-doped lutetium oxyorthosilicate array (12 x 12 crystals, 0.8 x 1.66 x 3.75 mm(3) each) directly coupled to a position-sensitive photomultiplier tube (PS-PMT). The detector signals were fed into the scanner electronics to establish coincidences between the 2 systems. The detector was mounted to a rotation stage that is attached to the scanner via the custom mounting plate after removing the transmission source holder. The rotation stage was concentric with the center of the scanner. The angular offset of the insert detector was calibrated via optimizing point-source images. In all imaging experiments, coincidence data were collected from 9 angles to provide 180 degrees sampling. A (22)Na point source was imaged at different offsets from the center to characterize the in-plane resolution of the insert system. A (68)Ge point source was stepped across the axial field of view to measure the sensitivity of the system. A 23.2-g mouse was injected with 38.5 MBq of (18)F-fluoride and imaged at 3 h after injection for 2 h. The transverse image resolution of the PET insert device ranges from 1.1- to 1.4-mm full width at half maximum (FWHM) without correction for the point-source dimension. This corresponds to approximately 33% improvement over the resolution of the original scanner (1.7- to 1.8-mm FWHM) in 2 of the 3 directions. The sensitivity of the device is 0.064% at the center of the field, 46-fold lower than the sensitivity of an existing animal PET scanner. The mouse bone scan had improved image resolution using the PET insert device over that of the existing animal PET scanner alone. We have demonstrated the feasibility of using a high-resolution insert

  12. Validation of GEANT3 simulation studies with a dual-head PMT ClearPET TM prototype

    CERN Document Server

    Ziemons, K; Streun, M; Pietrzyk, U

    2004-01-01

    The ClearPET TM project is proposed by working groups of the Crystal Clear Collaboration (CCC) to develop a 2/sup nd/ generation high performance small animal positron emission tomograph (PET). High sensitivity and high spatial resolution is foreseen for the ClearPET TM camera by using a phoswich arrangement combining mixed lutetium yttrium aluminum perovskite (LuYAP:Ce) and lutetium oxyorthosilicate (LSO) scintillating crystals. Design optimizations for the first photomultiplier tube (PMT) based ClearPET camera are done with a Monte-Carlo simulation package implemented on GEANT3 (CERN, Geneva, Switzerland). A dual-head prototype has been built to test the frontend electronics and was used to validate the implementation of the GEANT3 simulation tool. Multiple simulations were performed following the experimental protocols to measure the intrinsic resolution and the sensitivity profile in axial and radial direction. Including a mean energy resolution of about 27.0% the simulated intrinsic resolution is about (...

  13. Do carotid MR surface coils affect PET quantification in PET/MR imaging?

    Energy Technology Data Exchange (ETDEWEB)

    Willemink, Martin J; Eldib, Mootaz [Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY (United States); Leiner, Tim [Department of Radiology, University Medical Center Utrecht, Utrecht (Netherlands); Fayad, Zahi A; Mani, Venkatesh [Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY (United States)

    2015-05-18

    To evaluate the effect of surface coils for carotid MR imaging on PET quantification in a clinical simultaneous whole-body PET/MR scanner. A cylindrical phantom was filled with a homogeneous 2L water-FDG mixture at a starting dose of 301.2MBq. Clinical PET/MR and PET/CT systems were used to acquire PET-data without a coil (reference standard) and with two carotid MRI coils (Siemens Special Purpose 8-Channel and Machnet 4-Channel Phased Array). PET-signal attenuation was evaluated with Osirix using 51 (PET/MR) and 37 (PET/CT) circular ROIs. Mean and maximum standardized uptake values (SUVs) were quantified for each ROI. Furthermore, SUVs of PET/MR and PET/CT were compared. For validation, a patient was scanned with an injected dose of 407.7MBq on both a PET/CT and a PET/MR system without a coil and with both coils. PET/MR underestimations were -2.2% (Siemens) and -7.8% (Machnet) for SUVmean, and -1.2% (Siemens) and -3.3% (Machnet) for SUVmax, respectively. For PET/CT, underestimations were -1.3% (Siemens) and -1.4% (Machnet) for SUVmean and -0.5% (both Siemens and Machnet) for SUVmax, respectively using no coil data as reference. Except for PET/CT SUVmax values all differences were significant. SUVs differed significantly between PET/MR and PET/CT with SUVmean values of 0.51-0.55 for PET/MR and 0.68-0.69 for PET/CT, respectively. The patient examination showed that median SUVmean values measured in the carotid arteries decreased from 0.97 without a coil to 0.96 (Siemens) and 0.88 (Machnet). Carotid surface coils do affect attenuation correction in both PET/MR and PET/CT imaging. Furthermore, SUVs differed significantly between PET/MR and PET/CT.

  14. A dedicated high-resolution PET imager for plant sciences.

    Science.gov (United States)

    Wang, Qiang; Mathews, Aswin J; Li, Ke; Wen, Jie; Komarov, Sergey; O'Sullivan, Joseph A; Tai, Yuan-Chuan

    2014-10-07

    PET provides an in vivo molecular and functional imaging capability that could be valuable for studying the interaction of plants in changing environments at the whole-plant level. We have developed a dedicated plant PET imager housed in a plant growth chamber (PGC), which provides a fully controlled environment. The system currently contains two types of scintillation detector modules from commercial small animal PET scanners: 84 microPET® detectors, which are made with scintillation crystal arrays of 2.2 mm(3) × 2.2 mm(3) × 10 mm(3) crystals to provide a large detection area; and 32 Inveon™ detectors, which are made with scintillation crystal arrays of 1.5 mm(3) × 1.5 mm(3) × 10 mm(3) crystals to provide higher spatial resolution. The detector modules are configured to form two half-rings, which provide a 15 cm-diameter trans-axial field of view (FOV) for dynamic tomographic imaging of small plants. Alternatively, the Inveon detectors can be reconfigured to form quarter-rings, which provide a 25 cm FOV using step-and-shoot motion. The imager contains two linear stages that move detectors vertically at different heights for multisection scanning, and two rotation stages to collect coincidence events from all angles when using the step-and-shoot acquisition. The detector modules and mechanical components of the imager are housed inside a PGC that regulates the environmental parameters. The system has a typical energy resolution of 15% for the Inveon detectors and 24% for the microPET detectors, timing resolution of 1.8 ns, and sensitivity of 1.3%, 1.4% and 3.0% measured at the center of the FOV, 5 cm off to the larger half-ring and 5 cm off to the smaller half-ring, respectively (with a 350-650 keV energy window and 3.1 ns timing window). The system's spatial resolution is capable of resolving rod sources of 1.25 mm diameter spaced 2.5 mm apart (center to center) using the ML-EM reconstruction algorithm. Preliminary imaging experiments

  15. PET/MRI in cancer patients

    DEFF Research Database (Denmark)

    Kjær, Andreas; Loft, Annika; Law, Ian

    2013-01-01

    described include brain tumors, pediatric oncology as well as lung, abdominal and pelvic cancer. In general the cases show that PET/MRI performs well in all these types of cancer when compared to PET/CT. However, future large-scale clinical studies are needed to establish when to use PET/MRI. We envision...... Medicine & PET at Rigshospitalet in Copenhagen we installed an integrated PET/MRI in December 2011. Here, we describe our first clinical PET/MR cases and discuss some of the areas within oncology where we envision promising future application of integrated PET/MR imaging in clinical routine. Cases...... that PET/MRI in oncology will prove to become a valuable addition to PET/CT in diagnosing, tailoring and monitoring cancer therapy in selected patient populations....

  16. Are Pets in the Bedroom a Problem?

    Science.gov (United States)

    Krahn, Lois E; Tovar, M Diane; Miller, Bernie

    2015-12-01

    The presence of pets in the bedroom can alter the sleep environment in ways that could affect sleep. Data were collected by questionnaire and interview from 150 consecutive patients seen at the Center for Sleep Medicine, Mayo Clinic in Arizona. Seventy-four people (49%) reported having pets, with 31 (41% of pet owners) having multiple pets. More than half of pet owners (56%) allowed their pets to sleep in the bedroom. Fifteen pet owners (20%) described their pets as disruptive, whereas 31 (41%) perceived their pets as unobtrusive or even beneficial to sleep. Health care professionals working with patients with sleep concerns should inquire about the presence of companion animals in the sleep environment to help them find solutions and optimize their sleep.

  17. Advances in Clinical PET/MRI Instrumentation.

    Science.gov (United States)

    Herzog, Hans; Lerche, Christoph

    2016-04-01

    In 2010, the first whole-body PET/MRI scanners installed for clinical use were the sequential Philips PET/MRI with PMT-based, TOF-capable technology and the integrated simultaneous Siemens PET/MRI. Avalanche photodiodes as non-magneto-sensitive readout electronics allowed PET integrated within the MRI. The experiences with these scanners showed that improvements of software aspects, such as attenuation correction, were necessary and that efficient protocols combining optimally PET and MRI must be still developed. In 2014, General Electric issued an integrated PET/MRI with SiPM-based PET detectors, allowing TOF-PET. Looking at the MRI components of current PET/MR imaging systems, primary improvements come from sequences and new coils.

  18. Nutritional sustainability of pet foods.

    Science.gov (United States)

    Swanson, Kelly S; Carter, Rebecca A; Yount, Tracy P; Aretz, Jan; Buff, Preston R

    2013-03-01

    Sustainable practices meet the needs of the present without compromising the ability of future generations to meet their needs. Applying these concepts to food and feed production, nutritional sustainability is the ability of a food system to provide sufficient energy and essential nutrients required to maintain good health in a population without compromising the ability of future generations to meet their nutritional needs. Ecological, social, and economic aspects must be balanced to support the sustainability of the overall food system. The nutritional sustainability of a food system can be influenced by several factors, including the ingredient selection, nutrient composition, digestibility, and consumption rates of a diet. Carbon and water footprints vary greatly among plant- and animal-based ingredients, production strategy, and geographical location. Because the pet food industry is based largely on by-products and is tightly interlinked with livestock production and the human food system, however, it is quite unique with regard to sustainability. Often based on consumer demand rather than nutritional requirements, many commercial pet foods are formulated to provide nutrients in excess of current minimum recommendations, use ingredients that compete directly with the human food system, or are overconsumed by pets, resulting in food wastage and obesity. Pet food professionals have the opportunity to address these challenges and influence the sustainability of pet ownership through product design, manufacturing processes, public education, and policy change. A coordinated effort across the industry that includes ingredient buyers, formulators, and nutritionists may result in a more sustainable pet food system.

  19. Game Design to Introduce Pets

    Directory of Open Access Journals (Sweden)

    Wahyu Febriyanto

    2017-02-01

    Full Text Available Introduction of animals from an early age can make children to love animals, especially pets. Children are the easiest group to receive stimulation, such as for example the stimulation of introducing children to the pet. Various media are used by parents to introduce pet. For examplle, by the media of books, multimedia, etc. One of the interesting media to introduce pet is with game. Of these problems then need to know how to make concept and design game to introduced pets for children age 3-6 years. In this paper, author formulate how to make pet game design include game genre, user interface design, image model selection, game characters, and game engine. The expected design of this game can be formulation of learning through proper game as a learning tool children. Game design derived from this writing by using model 2-dimensional images are funny and interesting coloring. And combines several game genres into one, or use the mini games that children do not get bored quickly. Design of GUI (Graphical User Interface is made as simple as possible so that children easily understand in playing this game, but also must use an interesting image

  20. Oxygen Barrier Properties and Melt Crystallization Behavior of Poly(ethylene terephthalate/Graphene Oxide Nanocomposites

    Directory of Open Access Journals (Sweden)

    Anna Szymczyk

    2015-01-01

    Full Text Available Poly(ethylene terephthalate nanocomposites with low loading (0.1–0.5 wt% of graphene oxide (GO have been prepared by using in situ polymerization method. TEM study of nanocomposites morphology has shown uniform distribution of highly exfoliated graphene oxide nanoplatelets in PET matrix. Investigations of oxygen permeability of amorphous films of nanocomposites showed that the nanocomposites had better oxygen barrier properties than the neat PET. The improvement of oxygen permeability for PET nanocomposite films over the neat PET is approximately factors of 2–3.3. DSC study on the nonisothermal crystallization behaviors proves that GO acts as a nucleating agent to accelerate the crystallization of PET matrix. The evolution of the lamellar nanostructure of nanocomposite and neat PET was monitored by SAXS during nonisothermal crystallization from the melt. It was found that unfilled PET and nanocomposite with the highest concentration of GO (0.5 wt% showed almost similar values of the long period (L=11.4 nm for neat PET and L=11.5 nm for PET/0.5GO.

  1. Realizing PET systems with 100 ps FWHM coincidence timing resolution (Conference Presentation)

    Science.gov (United States)

    Cates, Joshua; Levin, Craig

    2016-10-01

    The past two decades have seen much progress in coincidence timing resolution (CTR) for time-of-flight (TOF) capable positron emission tomography (PET) systems. With these advancements, clinical TOF-PET systems have achieved sub-400 ps FWHM (full-width-at-half-maximum) CTR, providing decreased patient radiation dose, shorter scan time, improved lesion detectability, increased accuracy and precision of lesion uptake measurements, and less sensitivity to errors in data correction techniques (normalization, scatter, and attenuation corrections). An important and long-standing milestone for the TOF-PET community is 100 ps FWHM CTR. At that level of timing performance, more than a factor of five improvement in image signal-to-noise ratio is possible compared to non-TOF-PET, with the potential for a transformational impact on quantitative PET imaging. With advancements in silicon photomultiplier technologies, novel scintillation materials and signal processing techniques, sub-100 ps CTR has been reported for relatively short scintillation crystal elements (3 mm length). However, clinical PET requires scintillation crystal elements that are 20 mm length or greater to provide adequate stopping power for 511 keV photons. This increased crystal length reduces the light collection efficiency and increases the scintillation photon transit time variance, resulting in degraded CTR. Significant strides have been made in achieving sub-150 ps FWHM CTR with 20 mm length crystals in single pixel, bench top experiments. We will present perspectives on the entire detection chain, from luminescence to signal processing and time-pickoff to enable 100 ps CTR at the level of full clinically-relevant detector modules.

  2. A high resolution TOF-PET concept with axial geometry and digital SiPM readout

    CERN Document Server

    Casella, C; Joram, C; Schneider, T

    2014-01-01

    The axial arrangement of long scintillation crystals is a promising concept in PET instrumentation to address the need for optimized resolution and sensitivity. Individual crystal readout and arrays of wavelength shifter strips placed orthogonally to the crystals lead to a 3D-detection of the annihilations photons. A fully operational demonstrator scanner, developed by the AX-PET collaboration, proved the potential of this concept in terms of energy and spatial resolution as well as sensitivity. This paper describes a feasibility study, performed on axial prototype detector modules with 100 mm long LYSO crystals, read out by the novel digital Silicon Photomultipliers (dSiPM) from Philips. With their highly integrated readout electronics and excellent intrinsic time resolution, dSiPMs allow for compact, axial detector modules which may extend the potential of the axial PET concept by time of fl ight capabilities (TOF-PET). A coincidence time resolution of 211 ps (FWHM) was achieved in the coincidence of two ax...

  3. Spatial resolution and sensitivity of the Inveon small-animal PET scanner.

    NARCIS (Netherlands)

    Visser, E.P.; Disselhorst, J.; Brom, M.; Laverman, P.; Gotthardt, M.; Oyen, W.J.G.; Boerman, O.C.

    2009-01-01

    The Inveon small-animal PET scanner is characterized by a large, 127-mm axial length and a 161-mm crystal ring diameter. The associated high sensitivity is obtained by using all lines of response (LORs) up to the maximum ring difference (MRD) of 79, for which the most oblique LORs form acceptance an

  4. Spatial resolution and sensitivity of the Inveon small-animal PET scanner.

    NARCIS (Netherlands)

    Visser, E.P.; Disselhorst, J.; Brom, M.; Laverman, P.; Gotthardt, M.; Oyen, W.J.G.; Boerman, O.C.

    2009-01-01

    The Inveon small-animal PET scanner is characterized by a large, 127-mm axial length and a 161-mm crystal ring diameter. The associated high sensitivity is obtained by using all lines of response (LORs) up to the maximum ring difference (MRD) of 79, for which the most oblique LORs form acceptance

  5. Parasites, pets, and people.

    Science.gov (United States)

    Marx, M B

    1991-03-01

    It is important for the family physician to understand that patients' relationships with their pets play an important role in helping maintain mental and physical health yet provide the potential for causing illness in the patient. Toxocara canis (dog roundworm) and Toxocara cati (cat roundworm) are the ascarids most commonly responsible for VLM and ocular larva migrans in humans. These roundworms live in their adult stage in the small intestine of the dog and cat where their eggs are passed in the feces. The eggs containing the infective larva are very sticky, thus an infant crawling around on the floor can easily pick these up on fingers that almost invariably end up in the mouth. Infections are usually mild and asymptomatic but with a persistent eosinophilia. Ocular larva migrans is the form usually occurring in older children and adults. Some public health veterinarians recommend that a puppy or kitten should not be obtained as a companion for a child who is not old enough to read, thus bypassing the crawling and toddler stages. Hookworm eggs, shed in the feces of infected dogs or cats, develop into the infective second stage within a week. Humans are usually infected when bare areas of skin such as bare feet or the torso come in contact with soil contaminated with the larvae. The second-stage larvae are able to penetrate the intact skin of humans and the foot pads of dogs and cats. In the United States, the common dog hookworm, A. caninum, is a widespread parasite. Human intestinal ancylostomiasis caused by this species is rare, with only six cases recorded in the literature. Infection in humans or animals by the common tapeworm of dogs and cats (Dipylidium caninum) requires ingestion of the intermediate host, the dog or cat flea containing the larva (cysticercoids) of the agent. Many cases in humans are asymptomatic. Dipylidiasis affects mainly infants and young children who may swallow a flea that hops up while the infant is crawling on the floor or fondling

  6. Compensation strategies for PET scanners with unconventional scanner geometry

    CERN Document Server

    Gundlich, B; Oehler, M

    2006-01-01

    The small animal PET scanner ClearPET®Neuro, developed at the Forschungszentrum Julich GmbH in cooperation with the Crystal Clear Collaboration (CERN), represents scanners with an unconventional geometry: due to axial and transaxial detector gaps ClearPet®Neuro delivers inhomogeneous sinograms with missing data. When filtered backprojection (FBP) or Fourier rebinning (FORE) are applied, strong geometrical artifacts appear in the images. In this contribution we present a method that takes the geometrical sensitivity into account and converts the measured sinograms into homogeneous and complete data. By this means artifactfree images are achieved using FBP or FORE. Besides an advantageous measurement setup that reduces inhomogeneities and data gaps in the sinograms, a modification of the measured sinograms is necessary. This modification includes two steps: a geometrical normalization and corrections for missing data. To normalize the measured sinograms, computed sinograms are used that describe the geometric...

  7. Monolithic glass block lasercom terminal: hardware proof of concept and test results

    Science.gov (United States)

    Carlson, Robert T.; Drake, Marvin D.; Jaeger, Jerold L.

    1995-04-01

    We summarize a compact lasercom terminal implementation based on a previously described system concept, and report on measurements made on a prototype optical system built on internal MITRE funds. This paper discusses the fabrication and test of an innovative hardware proof-of-concept for an advanced satellite lasercom terminal with a ten-fold size, weight, and production cost reduction over current practice. We have built and tested a proof-of-concept of the optics portion of a full duplex `monolithic glass block' (MGB) lasercom terminal. The complete MGB optical system is only 6' X 4' X 0.5' and weighs less than a pound. A complete terminal which includes a 3 - 4 inch telescope and gimbal could be implemented for as little as 15 - 30 pounds. The optical system test results are reported. Our approach uses emerging technologies and a highly integrated system design, based on representative system requirements for satellite crosslinks. Technology evaluation and system trades led to a novel optics design for a lasercom terminal, based on thin film coatings and half-inch glass cubes. The emerging photonic technologies employed include liquid crystals for solid state switching, automatic gain control, and microradian alignment; multi-layer dielectric films for optical bandpass filters, dichroic separation, and polarization control; semiconductor lasers with microlens optics; and an original design where all the optics are realized in planar thin films incorporated on small glass substrates, nominally one-half inch in size. These glass cubes are permanently bonded together to form a monolithic ensemble. Hence, we have coined this implementation the monolithic glass block (MGB) approach. Fused silica is used throughout for reasons of superb radiation resistance and thermal stability. The thin film filters, switches, and polarizers perform all the necessary functions in collimated light. This approach is feasible because the optical paths have been dramatically reduced to

  8. Parasites in pet reptiles

    Science.gov (United States)

    2011-01-01

    Exotic reptiles originating from the wild can be carriers of many different pathogens and some of them can infect humans. Reptiles imported into Slovenia from 2000 to 2005, specimens of native species taken from the wild and captive bred species were investigated. A total of 949 reptiles (55 snakes, 331 lizards and 563 turtles), belonging to 68 different species, were examined for the presence of endoparasites and ectoparasites. Twelve different groups (Nematoda (5), Trematoda (1), Acanthocephala (1), Pentastomida (1) and Protozoa (4)) of endoparasites were determined in 26 (47.3%) of 55 examined snakes. In snakes two different species of ectoparasites were also found. Among the tested lizards eighteen different groups (Nematoda (8), Cestoda (1), Trematoda (1), Acanthocephala (1), Pentastomida (1) and Protozoa (6)) of endoparasites in 252 (76.1%) of 331 examined animals were found. One Trombiculid ectoparasite was determined. In 563 of examined turtles eight different groups (Nematoda (4), Cestoda (1), Trematoda (1) and Protozoa (2)) of endoparasites were determined in 498 (88.5%) animals. In examined turtles three different species of ectoparasites were seen. The established prevalence of various parasites in reptiles used as pet animals indicates the need for examination on specific pathogens prior to introduction to owners. PMID:21624124

  9. Crystals in crystals

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Schmidt, I.; Carlsson, A.;

    2005-01-01

    A major factor governing the performance of catalytically active particles supported on a zeolite carrier is the degree of dispersion. It is shown that the introduction of noncrystallographic mesopores into zeolite single crystals (silicalite-1, ZSM-5) may increase the degree of particle dispersion...... of the zeolite particles, particularly after thermal treatment. When using mesoporous zeolites, the particles were evenly distributed throughout the mesopore system of the zeolitic support, even after calcination, leading to nanocrystals within mesoporous zeolite single crystals....

  10. Quantitative PET imaging with the 3T MR-BrainPET

    Energy Technology Data Exchange (ETDEWEB)

    Weirich, C., E-mail: c.weirich@fz-juelich.de [Forschungszentrum Jülich, Institute of Neuroscience and Medicine – 4, Juelich (Germany); Scheins, J.; Lohmann, P.; Tellmann, L. [Forschungszentrum Jülich, Institute of Neuroscience and Medicine – 4, Juelich (Germany); Byars, L.; Michel, C. [Siemens Healthcare, Molecular Imaging, Knoxville, TN (United States); Rota Kops, E.; Brenner, D.; Herzog, H.; Shah, N.J. [Forschungszentrum Jülich, Institute of Neuroscience and Medicine – 4, Juelich (Germany)

    2013-02-21

    The new hybrid imaging technology of MR-PET allows for simultaneous acquisition of versatile MRI contrasts and the quantitative metabolic imaging with PET. In order to achieve the quantification of PET images with minimal residual error the application of several corrections is crucial. In this work we present our results on quantification with the 3T MR BrainPET scanner.

  11. Effect of Attenuation Correction on Regional Quantification Between PET/MR and PET/CT

    DEFF Research Database (Denmark)

    Teuho, Jarmo; Johansson, Jarkko; Linden, Jani

    2016-01-01

    UNLABELLED: A spatial bias in brain PET/MR exists compared with PET/CT, because of MR-based attenuation correction. We performed an evaluation among 4 institutions, 3 PET/MR systems, and 4 PET/CT systems using an anthropomorphic brain phantom, hypothesizing that the spatial bias would be minimize...

  12. First results of the INSIDE in-beam PET scanner for the on-line monitoring of particle therapy treatments

    Science.gov (United States)

    Piliero, M. A.; Belcari, N.; Bisogni, M. G.; Camarlinghi, N.; Cerello, P.; Coli, S.; Del Guerra, A.; Ferrero, V.; Fiorina, E.; Giraudo, G.; Kostara, E.; Morrocchi, M.; Pennazio, F.; Peroni, C.; Pirrone, G.; Rivetti, A.; Rolo, M. D.; Rosso, V.; Sportelli, G.; Wheadon, R.

    2016-12-01

    Quality assessment of particle therapy treatments by means of PET systems has been carried out since late `90 and it is one of the most promising in-vivo non invasive monitoring techniques employed clinically. It can be performed with a diagnostic PET scanners installed outside the treatment room (off-line monitoring) or inside the treatment room (in-room monitoring). However the most efficient way is by integrating a PET scanner with the treatment delivery system (on-line monitoring) so that the biological wash out and the patient repositioning errors are minimized. In this work we present the performance of the in-beam PET scanner developed within the INSIDE project. The INSIDE PET scanner is made of two planar heads, 10 cm wide (transaxially) and 25 cm long (axially), composed of pixellated LFS crystals coupled to Hamamatsu MPPCs. Custom designed Front-End Electronics (FE) and Data AcQuisition (DAQ) systems allow an on-line reconstruction of PET images from separated in-spill and inter-spill data sets. The INSIDE PET scanner has been recently delivered at the CNAO (Pavia, Italy) hadrontherapy facility and the first experimental measurements have been carried out. Homogeneous PMMA phantoms and PMMA phantoms with small air and bone inserts were irradiated with monoenergetic clinical proton beams. The activity range was evaluated at various benchmark positions within the field of view to assess the homogeneity of response of the PET system. Repeated irradiations of PMMA phantoms with clinical spread out Bragg peak proton beams were performed to evaluate the reproducibility of the PET signal. The results found in this work show that the response of the INSIDE PET scanner is independent of the position within the radiation field. Results also show the capability of the INSIDE PET scanner to distinguish variations of the activity range due to small tissue inhomogeneities. Finally, the reproducibility of the activity range measurement was within 1 mm.

  13. PET for Staging of Esophageal Cancer

    Institute of Scientific and Technical Information of China (English)

    A.H.Hoelscher

    2004-01-01

    FDG-PET is of clinical value especially for detection of distant metastases or recurrent esophageal cancer. For the staging of primary tumor or locoregional lymph node metastasis PET is currently not suitable.

  14. Pet Meds Sending Kids to the ER

    Science.gov (United States)

    ... Health and Human Services. More Health News on: Child Safety Pet Health Poisoning Recent Health News Related MedlinePlus Health Topics Child Safety Pet Health Poisoning About MedlinePlus Site Map FAQs Customer ...

  15. Exercises in PET Image Reconstruction

    Science.gov (United States)

    Nix, Oliver

    These exercises are complementary to the theoretical lectures about positron emission tomography (PET) image reconstruction. They aim at providing some hands on experience in PET image reconstruction and focus on demonstrating the different data preprocessing steps and reconstruction algorithms needed to obtain high quality PET images. Normalisation, geometric-, attenuation- and scatter correction are introduced. To explain the necessity of those some basics about PET scanner hardware, data acquisition and organisation are reviewed. During the course the students use a software application based on the STIR (software for tomographic image reconstruction) library 1,2 which allows them to dynamically select or deselect corrections and reconstruction methods as well as to modify their most important parameters. Following the guided tutorial, the students get an impression on the effect the individual data precorrections have on image quality and what happens if they are forgotten. Several data sets in sinogram format are provided, such as line source data, Jaszczak phantom data sets with high and low statistics and NEMA whole body phantom data. The two most frequently used reconstruction algorithms in PET image reconstruction, filtered back projection (FBP) and the iterative OSEM (ordered subset expectation maximation) approach are used to reconstruct images. The exercise should help the students gaining an understanding what the reasons for inferior image quality and artefacts are and how to improve quality by a clever choice of reconstruction parameters.

  16. Evaluation of static physics performance of the jPET-D4 by Monte Carlo simulations.

    Science.gov (United States)

    Hasegawa, Tomoyuki; Yoshida, Eiji; Kobayashi, Ayako; Shibuya, Kengo; Nishikido, Fumihiko; Kobayashi, Tetsuya; Suga, Mikio; Yamaya, Taiga; Kitamura, Keishi; Maruyama, Koichi; Murayama, Hideo

    2007-01-07

    The jPET-D4 is the first PET scanner to introduce a unique four-layer depth-of-interaction (DOI) detector scheme in order to achieve high sensitivity and uniform high spatial resolution. This paper compares measurement and Monte Carlo simulation results of the static physics performance of this prototype research PET scanner. Measurement results include single and coincidence energy spectra, point and line source sensitivities, axial sensitivity profile (slice profile) and scatter fraction. We use GATE (Geant4 application for tomographic emission) as a Monte Carlo radiation transport model. Experimental results are reproduced well by the simulation model with reasonable assumptions on characteristic responses of the DOI detectors. In a previous study, the jPET-D4 was shown to provide a uniform spatial resolution as good as 3 mm (FHWM). In the present study, we demonstrate that a high sensitivity, 11.3 +/- 0.5%, is provided at the FOV centre. However, about three-fourths of this sensitivity is related to multiple-crystal events, for which some misidentification of the crystal cannot be avoided. Therefore, it is crucial to develop a more efficient way to identify the crystal of interaction and to reduce misidentification in order to make use of these high performance values simultaneously. We expect that effective sensitivity can be improved by replacing the GSO crystals with more absorptive crystals such as BGO and LSO. The results we describe here are essential to take full advantage of the next generation PET systems that have DOI recognition capability.

  17. Magnetic Resonance-based Motion Correction for Quantitative PET in Simultaneous PET-MR Imaging.

    Science.gov (United States)

    Rakvongthai, Yothin; El Fakhri, Georges

    2017-07-01

    Motion degrades image quality and quantitation of PET images, and is an obstacle to quantitative PET imaging. Simultaneous PET-MR offers a tool that can be used for correcting the motion in PET images by using anatomic information from MR imaging acquired concurrently. Motion correction can be performed by transforming a set of reconstructed PET images into the same frame or by incorporating the transformation into the system model and reconstructing the motion-corrected image. Several phantom and patient studies have validated that MR-based motion correction strategies have great promise for quantitative PET imaging in simultaneous PET-MR. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Investigation of a clinical PET detector module design that employs large-area avalanche photodetectors.

    Science.gov (United States)

    Peng, Hao; Olcott, Peter D; Spanoudaki, Virginia; Levin, Craig S

    2011-06-21

    We investigated the feasibility of designing an Anger-logic PET detector module using large-area high-gain avalanche photodiodes (APDs) for a brain-dedicated PET/MRI system. Using Monte Carlo simulations, we systematically optimized the detector design with regard to the scintillation crystal, optical diffuser, surface treatment, layout of large-area APDs, and signal-to-noise ratio (SNR, defined as the 511 keV photopeak position divided by the standard deviation of noise floor in an energy spectrum) of the APD devices. A detector prototype was built comprising an 8 × 8 array of 2.75 × 3.00 × 20.0 mm3 LYSO (lutetium-yttrium-oxyorthosilicate) crystals and a 22.0 × 24.0 × 9.0 mm3 optical diffuser. From the four designs of the optical diffuser tested, two designs employing a slotted diffuser are able to resolve all 64 crystals within the block with good uniformity and peak-to-valley ratio. Good agreement was found between the simulation and experimental results. For the detector employing a slotted optical diffuser, the energy resolution of the global energy spectrum after normalization is 13.4 ± 0.4%. The energy resolution of individual crystals varies between 11.3 ± 0.3% and 17.3 ± 0.4%. The time resolution varies between 4.85 ± 0.04 (center crystal), 5.17 ± 0.06 (edge crystal), and 5.18 ± 0.07 ns (corner crystal). The generalized framework proposed in this work helps to guide the design of detector modules for selected PET system configurations, including scaling the design down to a preclinical PET system, scaling up to a whole-body clinical scanner, as well as replacing APDs with other novel photodetectors that have higher gain or SNR such as silicon photomultipliers.

  19. AX-PET A novel PET detector concept with full 3D reconstruction

    CERN Document Server

    Braem, A; Séguinot, J; Dissertori, G; Djambazov, L; Lustermann, W; Nessi-Tedaldi, F; Pauss, F; Schinzel, D; Solevi, P; Lacasta, C; Oliver, J F; Rafecas, M; De Leo, R; Nappi, E; Vilardi, I; Chesi, E; Cochran, E; Honscheid, K; Kagan, H; Rudge, A; Smith, S; Weilhammer, P; Johnson, I; Renker, D; Clinthorne, N; Huh, S; Bolle, E; Stapnes, S; Meddi, F

    2009-01-01

    We describe the concept and first experimental tests of a novel 3D axial Positron Emission Tomography (PET) geometry. It allows for a new way of measuring the interaction point in the detector with very high precision. It is based on a matrix of long Lutetium-Yttrium OxyorthoSilicate (LYSO) crystals oriented in the axial direction, each coupled to one Geiger Mode Avalanche Photodiode (G-APD) array. To derive the axial coordinate, Wave Length Shifter (WLS) strips are mounted orthogonally and interleaved between the crystals. The light from the WLS strips is read by custom-made G-APDs. The weighted mean of the signals in the WLS strips has proven to give very precise axial resolution. The achievable resolution along the three axes is mainly driven by the dimensions of the LYSO crystals and WLS strips. This concept is inherently free of parallax errors. Furthermore, it will allow identification of Compton interactions in the detector and for reconstruction of a fraction of them, which is expected to enhance imag...

  20. A Novel Method for the Image Quality assessment of PET Scanners by Monte Carlo simulations: Effect of the scintillator

    Science.gov (United States)

    Karpetas, G. E.; Michail, C. M.; Fountos, G. P.; Kalyvas, N. I.; Valais, I. G.; Kandarakis, I. S.; Panayiotakis, G. S.

    2014-03-01

    The aim of the present study was to propose a comprehensive method for PET scanners image quality assessment, by the simulation of a thin layer chromatography (TLC) flood source with a previous validated Monte-Carlo (MC) model. The model was developed by using the GATE MC package and reconstructed images were obtained using the STIR software, with cluster computing. The PET scanner simulated was the GE Discovery-ST. The TLC source was immersed in 18F-FDG bath solution (1MBq) in order to assess image quality. The influence of different scintillating crystals on PET scanner's image quality, in terms of the MTF, the NNPS and the DQE, was investigated. Images were reconstructed by the commonly used FBP2D, FPB3DRP and the OSMAPOSL (15 subsets, 3 iterations) reprojection algorithms. The PET scanner configuration, incorporating LuAP crystals, provided the optimum MTF values in both 2D and 3DFBP whereas the corresponding configuration with BGO crystals was found with the higher MTF values after OSMAPOSL. The scanner incorporating BGO crystals were also found with the lowest noise levels and the highest DQE values after all image reconstruction algorithms. The plane source can be also useful for the experimental image quality assessment of PET and SPECT scanners in clinical practice.

  1. Noise and physical limits to maximum resolution of PET images

    Energy Technology Data Exchange (ETDEWEB)

    Herraiz, J.L.; Espana, S. [Dpto. Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain); Vicente, E.; Vaquero, J.J.; Desco, M. [Unidad de Medicina y Cirugia Experimental, Hospital GU ' Gregorio Maranon' , E-28007 Madrid (Spain); Udias, J.M. [Dpto. Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain)], E-mail: jose@nuc2.fis.ucm.es

    2007-10-01

    In this work we show that there is a limit for the maximum resolution achievable with a high resolution PET scanner, as well as for the best signal-to-noise ratio, which are ultimately related to the physical effects involved in the emission and detection of the radiation and thus they cannot be overcome with any particular reconstruction method. These effects prevent the spatial high frequency components of the imaged structures to be recorded by the scanner. Therefore, the information encoded in these high frequencies cannot be recovered by any reconstruction technique. Within this framework, we have determined the maximum resolution achievable for a given acquisition as a function of data statistics and scanner parameters, like the size of the crystals or the inter-crystal scatter. In particular, the noise level in the data as a limitation factor to yield high-resolution images in tomographs with small crystal sizes is outlined. These results have implications regarding how to decide the optimal number of voxels of the reconstructed image or how to design better PET scanners.

  2. Performance of the Tachyon Time-of-Flight PET Camera.

    Science.gov (United States)

    Peng, Q; Choong, W-S; Vu, C; Huber, J S; Janecek, M; Wilson, D; Huesman, R H; Qi, Jinyi; Zhou, Jian; Moses, W W

    2015-02-01

    We have constructed and characterized a time-of-flight Positron Emission Tomography (TOF PET) camera called the Tachyon. The Tachyon is a single-ring Lutetium Oxyorthosilicate (LSO) based camera designed to obtain significantly better timing resolution than the ~ 550 ps found in present commercial TOF cameras, in order to quantify the benefit of improved TOF resolution for clinically relevant tasks. The Tachyon's detector module is optimized for timing by coupling the 6.15 × 25 mm(2) side of 6.15 × 6.15 × 25 mm(3) LSO scintillator crystals onto a 1-inch diameter Hamamatsu R-9800 PMT with a super-bialkali photocathode. We characterized the camera according to the NEMA NU 2-2012 standard, measuring the energy resolution, timing resolution, spatial resolution, noise equivalent count rates and sensitivity. The Tachyon achieved a coincidence timing resolution of 314 ps +/- ps FWHM over all crystal-crystal combinations. Experiments were performed with the NEMA body phantom to assess the imaging performance improvement over non-TOF PET. The results show that at a matched contrast, incorporating 314 ps TOF reduces the standard deviation of the contrast by a factor of about 2.3.

  3. Role of the Confined Geometry on the Crystallization of Poly(ethylene terephthlate) Ultrathin Films

    Institute of Scientific and Technical Information of China (English)

    Ying ZHANG; Yong Lai LU; De Yan SHEN

    2005-01-01

    The reflection-absorption infrared (RAIR) was employed to study the crystallization kinetic of poly (ethylene terephthalate) (PET) ultrathin films. During isothermal crystallization the thinner PET film shows a slower kinetic compared with the thicker film. Moreover, the final crystallinity of films with various thickness was found decrease with thickness. The result of fitting our data to Avrami equation showed that the Avrami exponents decrease with film thickness.

  4. A multiplexed TOF and DOI capable PET detector using a binary position sensitive network.

    Science.gov (United States)

    Bieniosek, M F; Cates, J W; Levin, C S

    2016-11-07

    Time of flight (TOF) and depth of interaction (DOI) capabilities can significantly enhance the quality and uniformity of positron emission tomography (PET) images. Many proposed TOF/DOI PET detectors require complex readout systems using additional photosensors, active cooling, or waveform sampling. This work describes a high performance, low complexity, room temperature TOF/DOI PET module. The module uses multiplexed timing channels to significantly reduce the electronic readout complexity of the PET detector while maintaining excellent timing, energy, and position resolution. DOI was determined using a two layer light sharing scintillation crystal array with a novel binary position sensitive network. A 20 mm effective thickness LYSO crystal array with four 3 mm  ×  3 mm silicon photomultipliers (SiPM) read out by a single timing channel, one energy channel and two position channels achieved a full width half maximum (FWHM) coincidence time resolution of 180  ±  2 ps with 10 mm of DOI resolution and 11% energy resolution. With sixteen 3 mm  ×  3 mm SiPMs read out by a single timing channel, one energy channel and four position channels a coincidence time resolution 204  ±  1 ps was achieved with 10 mm of DOI resolution and 15% energy resolution. The methods presented here could significantly simplify the construction of high performance TOF/DOI PET detectors.

  5. A multiplexed TOF and DOI capable PET detector using a binary position sensitive network

    Science.gov (United States)

    Bieniosek, M. F.; Cates, J. W.; Levin, C. S.

    2016-11-01

    Time of flight (TOF) and depth of interaction (DOI) capabilities can significantly enhance the quality and uniformity of positron emission tomography (PET) images. Many proposed TOF/DOI PET detectors require complex readout systems using additional photosensors, active cooling, or waveform sampling. This work describes a high performance, low complexity, room temperature TOF/DOI PET module. The module uses multiplexed timing channels to significantly reduce the electronic readout complexity of the PET detector while maintaining excellent timing, energy, and position resolution. DOI was determined using a two layer light sharing scintillation crystal array with a novel binary position sensitive network. A 20 mm effective thickness LYSO crystal array with four 3 mm  ×  3 mm silicon photomultipliers (SiPM) read out by a single timing channel, one energy channel and two position channels achieved a full width half maximum (FWHM) coincidence time resolution of 180  ±  2 ps with 10 mm of DOI resolution and 11% energy resolution. With sixteen 3 mm  ×  3 mm SiPMs read out by a single timing channel, one energy channel and four position channels a coincidence time resolution 204  ±  1 ps was achieved with 10 mm of DOI resolution and 15% energy resolution. The methods presented here could significantly simplify the construction of high performance TOF/DOI PET detectors.

  6. Piezoresistive Sensors Development Using Monolithic CMOS MEMS Technology

    Directory of Open Access Journals (Sweden)

    A. Chaehoi

    2011-04-01

    Full Text Available This paper presents the development of a monolithic CMOS-MEMS platform under the iDesign and SemeMEMS projects with the aim of jointly providing an open access “one-stop-shop” design and prototyping facility for integrated CMOS-MEMS. This work addresses the implementation of a 3-axis accelerometer and a pressure sensor using Semefab’s in-house 2-poly 1-metal CMOS process on a 380/4/15 μm SOI wafer; the membrane and the proof mass being micromachined using double-sided Deep Reactive Ion Etching (DRIE. This monolithic approach promises, in high volume production and using low complexity processes, a dramatic cost reduction over hybrid sensors. Furthermore, the embedded signal conditioning and the low-noise level in polysilicon gauges enables high performance to be achieved by implementing dedicated on-chip amplification and filtering circuitry.

  7. Fabrication and characterization of monolithic solid oxide fuel cells

    Science.gov (United States)

    Minh, N. Q.; Horne, C. R.; Liu, F. S.; Moffatt, D. M.; Staszak, P. R.

    The monolithic solid oxide fuel cell (MSOFC) is an all-ceramic structure in which cell components are configured in a compact corrugated array. The MSOFC shows promise for use in a wide range of sizes (kilowatt to megawatt) and a broad spectrum of applications (electric utility, cogeneration, on-site, and aerospace power). A process based on the tape calendering technique is being developed for the fabrication of the MSOFC. MSOFC single cells have been fabricated by this process without cracking or delamination. Stacks of various sizes have been formed and processed to demonstrate fabricability of the monolithic structure. Extensive physical, chemical, electrical, and electrochemical characterization of fabricated samples has been carried out to confirm the required properties of each cell component. The characterization results reported have been used to support material and fabrication improvements.

  8. Low-bandgap, monolithic, multi-bandgap, optoelectronic devices

    Science.gov (United States)

    Wanlass, Mark W.; Carapella, Jeffrey J.

    2014-07-08

    Low bandgap, monolithic, multi-bandgap, optoelectronic devices (10), including PV converters, photodetectors, and LED's, have lattice-matched (LM), double-heterostructure (DH), low-bandgap GaInAs(P) subcells (22, 24) including those that are lattice-mismatched (LMM) to InP, grown on an InP substrate (26) by use of at least one graded lattice constant transition layer (20) of InAsP positioned somewhere between the InP substrate (26) and the LMM subcell(s) (22, 24). These devices are monofacial (10) or bifacial (80) and include monolithic, integrated, modules (MIMs) (190) with a plurality of voltage-matched subcell circuits (262, 264, 266, 270, 272) as well as other variations and embodiments.

  9. Design and Testing of Prototypic Elements Containing Monolithic Fuel

    Energy Technology Data Exchange (ETDEWEB)

    N.E. Woolstenhulme; M.K. Meyer; D.M. Wachs

    2011-10-01

    The US fuel development team has performed numerous irradiation tests on small to medium sized specimens containing low enriched uranium fuel designs. The team is now focused on qualification and demonstration of the uranium-molybdenum Base Monolithic Design and has entered the next generation of testing with the design and irradiation of prototypic elements which contain this fuel. The designs of fuel elements containing monolithic fuel, such as AFIP-7 (which is currently under irradiation) and RERTR-FE (which is currently under fabrication), are appropriate progressions relative to the technology life cycle. The culmination of this testing program will occur with the design, fabrication, and irradiation of demonstration products to include the base fuel demonstration and design demonstration experiments. Future plans show that design, fabrication, and testing activities will apply the rigor needed for a demonstration campaign.

  10. From 1D to 3D - macroscopic nanowire aerogel monoliths

    Science.gov (United States)

    Cheng, Wei; Rechberger, Felix; Niederberger, Markus

    2016-07-01

    Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying.Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying. Electronic supplementary information (ESI) available: Experimental details, SEM and TEM images, and digital photographs. See DOI: 10.1039/c6nr04429h

  11. Low-bandgap, monolithic, multi-bandgap, optoelectronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Wanlass, Mark W.; Carapella, Jeffrey J.

    2016-01-05

    Low bandgap, monolithic, multi-bandgap, optoelectronic devices (10), including PV converters, photodetectors, and LED's, have lattice-matched (LM), double-heterostructure (DH), low-bandgap GaInAs(P) subcells (22, 24) including those that are lattice-mismatched (LMM) to InP, grown on an InP substrate (26) by use of at least one graded lattice constant transition layer (20) of InAsP positioned somewhere between the InP substrate (26) and the LMM subcell(s) (22, 24). These devices are monofacial (10) or bifacial (80) and include monolithic, integrated, modules (MIMs) (190) with a plurality of voltage-matched subcell circuits (262, 264, 266, 270, 272) as well as other variations and embodiments.

  12. Low-bandgap, monolithic, multi-bandgap, optoelectronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Wanlass, Mark W.; Carapella, Jeffrey J.

    2014-07-08

    Low bandgap, monolithic, multi-bandgap, optoelectronic devices (10), including PV converters, photodetectors, and LED's, have lattice-matched (LM), double-heterostructure (DH), low-bandgap GaInAs(P) subcells (22, 24) including those that are lattice-mismatched (LMM) to InP, grown on an InP substrate (26) by use of at least one graded lattice constant transition layer (20) of InAsP positioned somewhere between the InP substrate (26) and the LMM subcell(s) (22, 24). These devices are monofacial (10) or bifacial (80) and include monolithic, integrated, modules (MIMs) (190) with a plurality of voltage-matched subcell circuits (262, 264, 266, 270, 272) as well as other variations and embodiments.

  13. Low-bandgap, monolithic, multi-bandgap, optoelectronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Wanlass, Mark W.; Carapella, Jeffrey J.

    2016-03-22

    Low bandgap, monolithic, multi-bandgap, optoelectronic devices (10), including PV converters, photodetectors, and LED's, have lattice-matched (LM), double-heterostructure (DH), low-bandgap GaInAs(P) subcells (22, 24) including those that are lattice-mismatched (LMM) to InP, grown on an InP substrate (26) by use of at least one graded lattice constant transition layer (20) of InAsP positioned somewhere between the InP substrate (26) and the LMM subcell(s) (22, 24). These devices are monofacial (10) or bifacial (80) and include monolithic, integrated, modules (MIMs) (190) with a plurality of voltage-matched subcell circuits (262, 264, 266, 270, 272) as well as other variations and embodiments.

  14. Development of stable monolithic wide-field Michelson interferometers

    Science.gov (United States)

    Wan, Xiaoke; Ge, Jian; Chen, Zhiping

    2011-07-01

    Bulk wide-field Michelson interferometers are very useful for high precision applications in remote sensing and astronomy. A stable monolithic Michelson interferometer is a key element in high precision radial velocity (RV) measurements for extrasolar planets searching and studies. Thermal stress analysis shows that matching coefficients of thermal expansion (CTEs) is a critical requirement for ensuring interferometer stability. This requirement leads to a novel design using BK7 and LAK7 materials, such that the monolithic interferometer is free from thermal distortion. The processes of design, fabrication, and testing of interferometers are described in detail. In performance evaluations, the field angle is typically 23.8° and thermal sensitivity is typically -2.6×10-6/° C near 550nm, which corresponds to ˜800m/s/°C in the RV scale. Low-cost interferometer products have been commissioned in multiple RV instruments, and they are producing high stability performance over long term operations.

  15. Development of stable monolithic wide-field Michelson interferometers.

    Science.gov (United States)

    Wan, Xiaoke; Ge, Jian; Chen, Zhiping

    2011-07-20

    Bulk wide-field Michelson interferometers are very useful for high precision applications in remote sensing and astronomy. A stable monolithic Michelson interferometer is a key element in high precision radial velocity (RV) measurements for extrasolar planets searching and studies. Thermal stress analysis shows that matching coefficients of thermal expansion (CTEs) is a critical requirement for ensuring interferometer stability. This requirement leads to a novel design using BK7 and LAK7 materials, such that the monolithic interferometer is free from thermal distortion. The processes of design, fabrication, and testing of interferometers are described in detail. In performance evaluations, the field angle is typically 23.8° and thermal sensitivity is typically -2.6×10(-6)/°C near 550 nm, which corresponds to ∼800 m/s/°C in the RV scale. Low-cost interferometer products have been commissioned in multiple RV instruments, and they are producing high stability performance over long term operations.

  16. Affinity Monolith-Integrated Microchips for Protein Purification and Concentration.

    Science.gov (United States)

    Gao, Changlu; Sun, Xiuhua; Wang, Huaixin; Qiao, Wei; Hu, Bo

    2016-01-01

    Affinity chromatography is a valuable method to purify and concentrate minute amount of proteins. Monoliths with epoxy groups for affinity immobilization were prepared by direct in-situ photopolymerization of glycidyl methacrylate and ethylene glycol dimethacrylate in porogenic solvents consisting of 1-dodecanol and cyclohexanol. By integrating affinity monoliths onto a microfluidic system, targeted biomolecules can be captured and retained on affinity column, while other biomolecules having no specific interactions toward the immobilized ligands flow through the microchannel. Therefore, proteins which remain on the affinity column are purified and concentrated, and then eluted by appropriate solutions and finally, separated by microchip capillary electrophoresis. This integrated microfluidic device has been applied to the purification and separation of specific proteins (FITC-labeled human serum albumin and IgG) in a mixture.

  17. THE CHARACTERISTICS OF EEC PET INSTRUMENTATION

    NARCIS (Netherlands)

    PAANS, AMJ

    1991-01-01

    As a result of a Guide-Questionnaire distributed among all European PET centers an inventory of the European PET instrumentation has become available in a data base. An overview and analysis of the European PET equipment, cyclotrons, scanners and software, together with some global information on th

  18. 36 CFR 13.1106 - Pets.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Pets. 13.1106 Section 13.1106 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK... Provisions § 13.1106 Pets. Pets are prohibited except— (a) On the Bartlett Cove Public Use Dock; (b) On...

  19. Pets in the family: practical approaches.

    Science.gov (United States)

    Hodgson, Kate; Darling, Marcia

    2011-01-01

    Adapting family life cycle theory to include pets provides veterinarians with a framework for understanding and reinforcing the human-animal bond. The family genogram with pets is a practice tool that identifies all people and pets in the family, enhancing the practice of One Health at the community level.

  20. 7 CFR 503.11 - Pets.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Pets. 503.11 Section 503.11 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL RESEARCH SERVICE, DEPARTMENT OF AGRICULTURE CONDUCT ON PLUM ISLAND ANIMAL DISEASE CENTER § 503.11 Pets. No pets or animals of any kind may be...

  1. 36 CFR 13.978 - Pets.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Pets. 13.978 Section 13.978 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK... (fda) § 13.978 Pets. Possessing a pet is prohibited— (a) In the FDA, except in public parking areas,...

  2. 7 CFR 500.10 - Pets.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Pets. 500.10 Section 500.10 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL RESEARCH SERVICE, DEPARTMENT OF AGRICULTURE NATIONAL ARBORETUM Conduct on U.S. National Arboreturm Property § 500.10 Pets. Pets brought upon...

  3. 36 CFR 13.1310 - Pets.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Pets. 13.1310 Section 13.1310... SYSTEM UNITS IN ALASKA Special Regulations-Kenai Fjords National Park General Provisions § 13.1310 Pets. (a) Pets are prohibited— (1) In the Exit Glacier Developed Area except in the parking lot, on...

  4. 36 CFR 13.1234 - Pets.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Pets. 13.1234 Section 13.1234 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK... § 13.1234 Pets. Possessing a pet in the BCDA is prohibited....

  5. The modification behaviour for Si implanted PET

    Institute of Scientific and Technical Information of China (English)

    吴瑜光; 张通和; 刘安东; 张旭; 周固

    2003-01-01

    Polyethylene terephthalate (PET) has been modified by Si ion implantation with a dose ranging from 1 × 1016 to 2 × 1017 ions /cm2 using a metal vapor vacuum arc(MEVVA)source. The surface morphology was observed by atomic force microscopy (AFM). The change in the microstructure of Si implanted PET was observed with a transmission electron microscope (TEM). It is believed that the change would improve the conductive properties and wear resistance. The electrical properties of PET have been improved via Si ion implantation. The resistivity of implanted PET decreased obviously with an increase in ion dose. When Si ion dose was 2 × 1017 cm?2, the resistivity of PET could be less than 7.9 Ω@m. The surface hardness and modulus increased obviously. The mechanical property of the implanted PET has been modified greatly. The hardness and modulus of Si implanted PET with a dose of 2 × 1017/cm2 are 12.5 and 2.45 times greater than those of pristine PET, respectively. The area of cutting groove for Si implanted PET is narrower and shallower than those of the unimplanted PET. So the wear resistance is greatly raised. In comparison with metal ion implantation, the improvement of mechanical properties is obvious in ion implantation into PET. Si ion beam modification mechanism of PET is discussed.

  6. THE CHARACTERISTICS OF EEC PET INSTRUMENTATION

    NARCIS (Netherlands)

    PAANS, AMJ

    1991-01-01

    As a result of a Guide-Questionnaire distributed among all European PET centers an inventory of the European PET instrumentation has become available in a data base. An overview and analysis of the European PET equipment, cyclotrons, scanners and software, together with some global information on

  7. THE CHARACTERISTICS OF EEC PET INSTRUMENTATION

    NARCIS (Netherlands)

    PAANS, AMJ

    1991-01-01

    As a result of a Guide-Questionnaire distributed among all European PET centers an inventory of the European PET instrumentation has become available in a data base. An overview and analysis of the European PET equipment, cyclotrons, scanners and software, together with some global information on th

  8. Pet therapy: dogs de-stress students.

    Science.gov (United States)

    Young, Judith S

    2012-01-01

    Research supports the efficacy of the human-animal bond and pet therapy in a variety of settings. At nursing students' request at one school, the author began offering pet therapy prior to examinations. Anecdotal evidence of a study with the author's Golden Retriever, Goldilocks, demonstrates that pet therapy can reduce test anxiety and improve nursing student performance.

  9. Understanding advertising in pet nutrition.

    Science.gov (United States)

    Brown, R G

    1994-04-01

    Advertising is part of the effort to attract attention of consumers to products, in this case, pet foods. It is generally benign in its effect, but it can be misleading, although rarely deliberately so. It uses a specialized vocabulary, which must be mastered if one is to understand what is intended. For all of the expense and effort, advertising figures directly in relatively few decisions to purchase. Its main intention is to call our attention to a particular pet food and to give that product an image. If the pet food does not perform in the consumer's hands, then all of the advertising on earth will not be persuasive. On the other hand, if a product performs well, the word-of-mouth will be positive and that mode of advertising is one of the most effective.

  10. PET and SPECT in neurology

    Energy Technology Data Exchange (ETDEWEB)

    Dierckx, Rudi A.J.O. [Groningen University Medical Center (Netherlands). Dept. of Nuclear Medicine and Molecular Imaging; Ghent Univ. (Belgium). Dept. of Radiology and Nuclear Medicine; Vries, Erik F.J. de; Waarde, Aren van [Groningen University Medical Center (Netherlands). Dept. of Nuclear Medicine and Molecular Imaging; Otte, Andreas (ed.) [Univ. of Applied Sciences Offenburg (Germany). Faculty of Electrical Engineering and Information Technology

    2014-07-01

    PET and SPECT in Neurology highlights the combined expertise of renowned authors whose dedication to the investigation of neurological disorders through nuclear medicine technology has achieved international recognition. Classical neurodegenerative disorders are discussed as well as cerebrovascular disorders, brain tumors, epilepsy, head trauma, coma, sleeping disorders, and inflammatory and infectious diseases of the CNS. The latest results in nuclear brain imaging are detailed. Most chapters are written jointly by a clinical neurologist and a nuclear medicine specialist to ensure a multidisciplinary approach. This state-of-the-art compendium will be valuable to anybody in the field of neuroscience, from the neurologist and the radiologist/nuclear medicine specialist to the interested general practitioner and geriatrician. It is the second volume of a trilogy on PET and SPECT imaging in the neurosciences, the other volumes covering PET and SPECT in psychiatry and in neurobiological systems.

  11. Dynamic response of monolithic and laminate/particulate reactive mixtures

    OpenAIRE

    Wei, Chung-Ting

    2011-01-01

    Two dynamic compression methods were applied to a monolithic metal and reactive mixtures to investigate their responses: (a) Dynamic experiments using a split Hopkinson pressure bar were applied to reactive mixtures densified by explosive consolidation in order to establish their mechanical response and failure mechanisms. (b) Laser compression and release, which can impart high stresses, up to hundreds GPa, in times of nanoseconds and fractions thereof, was applied to establish the spalling ...

  12. Advanced on-chip divider for monolithic microwave VCO's

    Science.gov (United States)

    Peterson, Weddell C.

    1989-01-01

    High frequency division on a monolithic circuit is a critical technology required to significantly enhance the performance of microwave and millimeter-wave phase-locked sources. The approach used to meet this need is to apply circuit design practices which are essentially 'microwave' in nature to the basically 'digital' problem of high speed division. Following investigation of several promising circuit approaches, program phase 1 culminated in the design and layout of an 8.5 GHz (Deep Space Channel 14) divide by four circuit based on a dynamic mixing divider circuit approach. Therefore, during program phase 2, an 8.5 GHz VCO with an integral divider which provides a phase coherent 2.125 GHz reference signal for phase locking applications was fabricated and optimized. Complete phase locked operation of the monolithic GaAs devices (VCO, power splitter, and dynamic divider) was demonstrated both individually and as an integrated unit. The fully functional integrated unit in a suitable test fixture was delivered to NASA for engineering data correlation. Based on the experience gained from this 8.5 GHz super component, a monolithic GaAs millimeter-wave dynamic divider for operation with an external VCO was also designed, fabricated, and characterized. This circuit, which was also delivered to NASA, demonstrated coherent division by four at an input frequency of 24.3 GHz. The high performance monolithic microwave VCO with a coherent low frequency reference output described in this report and others based on this technology will greatly benefit advanced communications systems in both the DoD and commercial sectors. Signal processing and instrumentation systems based on phase-locking loops will also attain enhanced performance at potentially reduced cost.

  13. Advanced on-chip divider for monolithic microwave VCO's

    Science.gov (United States)

    Peterson, Weddell C.

    1989-05-01

    High frequency division on a monolithic circuit is a critical technology required to significantly enhance the performance of microwave and millimeter-wave phase-locked sources. The approach used to meet this need is to apply circuit design practices which are essentially 'microwave' in nature to the basically 'digital' problem of high speed division. Following investigation of several promising circuit approaches, program phase 1 culminated in the design and layout of an 8.5 GHz (Deep Space Channel 14) divide by four circuit based on a dynamic mixing divider circuit approach. Therefore, during program phase 2, an 8.5 GHz VCO with an integral divider which provides a phase coherent 2.125 GHz reference signal for phase locking applications was fabricated and optimized. Complete phase locked operation of the monolithic GaAs devices (VCO, power splitter, and dynamic divider) was demonstrated both individually and as an integrated unit. The fully functional integrated unit in a suitable test fixture was delivered to NASA for engineering data correlation. Based on the experience gained from this 8.5 GHz super component, a monolithic GaAs millimeter-wave dynamic divider for operation with an external VCO was also designed, fabricated, and characterized. This circuit, which was also delivered to NASA, demonstrated coherent division by four at an input frequency of 24.3 GHz. The high performance monolithic microwave VCO with a coherent low frequency reference output described in this report and others based on this technology will greatly benefit advanced communications systems in both the DoD and commercial sectors. Signal processing and instrumentation systems based on phase-locking loops will also attain enhanced performance at potentially reduced cost.

  14. Clinical assessment of enamel wear caused by monolithic zirconia crowns.

    Science.gov (United States)

    Stober, T; Bermejo, J L; Schwindling, F S; Schmitter, M

    2016-08-01

    The purpose of this study was to measure enamel wear caused by antagonistic monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia full molar crowns were placed in 20 patients. Patients with high activity of the masseter muscle at night (bruxism) were excluded. For analysis of wear, vinylpolysiloxane impressions were prepared after crown incorporation and at 6-, 12-, and 24-month follow-up. Wear of the occlusal contact areas of the crowns, of their natural antagonists, and of two contralateral natural antagonists (control teeth) was measured by use of plaster replicas and a 3D laser-scanning device. Differences of wear between the zirconia crown antagonists and the control teeth were investigated by means of two-sided paired Student's t-tests and linear regression analysis. After 2 years, mean vertical loss was 46 μm for enamel opposed to zirconia, 19-26 μm for contralateral control teeth and 14 μm for zirconia crowns. Maximum vertical loss was 151 μm for enamel opposed to zirconia, 75-115 μm for control teeth and 60 μm for zirconia crowns. Statistical analysis revealed significant differences between wear of enamel by zirconia-opposed teeth and by control teeth. Gender, which significantly affected wear, was identified as a possible confounder. Monolithic zirconia crowns generated more wear of opposed enamel than did natural teeth. Because of the greater wear caused by other dental ceramics, the use of monolithic zirconia crowns may be justified.

  15. Applications of monolithic fiber interferometers and actively controlled fibers

    OpenAIRE

    Rugeland, Patrik

    2013-01-01

    The objective of this thesis was to develop applications of monolithic fiber devices and actively controlled fibers. A special twin-core fiber known as a ‘Gemini’ fiber was used to construct equal arm-length fiber interferometers, impervious to temperature and mechanical perturbations. A broadband add/drop multiplexer was constructed by inscribing fiber Bragg gratings in the arms of a Gemini Mach-Zehnder interferometer. A broadband interferometric nanosecond switch was constructed from a micr...

  16. Monolithically Integrated Ge-on-Si Active Photonics

    OpenAIRE

    Jifeng Liu

    2014-01-01

    Monolithically integrated, active photonic devices on Si are key components in Si-based large-scale electronic-photonic integration for future generations of high-performance, low-power computation and communication systems. Ge has become an interesting candidate for active photonic devices in Si photonics due to its pseudo-direct gap behavior and compatibility with Si complementary metal oxide semiconductor (CMOS) processing. In this paper, we present a review of the recent progress in Ge-on...

  17. Extended Leach Testing of Simulated LAW Cast Stone Monoliths

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R. Jeffrey [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lanigan, David C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Westsik, Joseph H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Williams, Benjamin D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jung, H. B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Guohui [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-08-12

    This revision to the original report adds two longer term leach sets of data to the report and provides more discussion and graphics on how to interpret the results from long-term laboratory leach tests. The leach tests were performed at Pacific Northwest National Laboratory (PNNL) for Washington River Protection Solutions (WRPS) to evaluate the release of key constituents from monoliths of Cast Stone prepared with four simulated low-activity waste (LAW) liquid waste streams.

  18. A Distributed Model of Four-Port Monolithic Transformer

    OpenAIRE

    Lee, Dong Ho; Ko, Sangsoo; Jeon, Sang-Hoon; Park, Jae-Woo; Hong, Songcheol

    2004-01-01

    This paper deals with modeling of a monolithic spiral transformer. The transformer is designed and fabricated as a symmetrical octagonal spiral structure using two-metal layer process on GaAs substrate for input balun applications of 2 GHz and 5 GHz push-pull power amplifiers. A distributed model of the transformer is developed to fit in wide frequency range with four ports. The model includes the skin effect which describes increase in series resistance with frequency. Six different se...

  19. Fusion of binding domains to Thermobifida cellulosilytica cutinase to tune sorption characteristics and enhancing PET hydrolysis.

    Science.gov (United States)

    Ribitsch, Doris; Yebra, Antonio Orcal; Zitzenbacher, Sabine; Wu, Jing; Nowitsch, Susanne; Steinkellner, Georg; Greimel, Katrin; Doliska, Ales; Oberdorfer, Gustav; Gruber, Christian C; Gruber, Karl; Schwab, Helmut; Stana-Kleinschek, Karin; Acero, Enrique Herrero; Guebitz, Georg M

    2013-06-10

    A cutinase from Thermomyces cellullosylitica (Thc_Cut1), hydrolyzing the synthetic polymer polyethylene terephthalate (PET), was fused with two different binding modules to improve sorption and thereby hydrolysis. The binding modules were from cellobiohydrolase I from Hypocrea jecorina (CBM) and from a polyhydroxyalkanoate depolymerase from Alcaligenes faecalis (PBM). Although both binding modules have a hydrophobic nature, it was possible to express the proteins in E. coli . Both fusion enzymes and the native one had comparable kcat values in the range of 311 to 342 s(-1) on pNP-butyrate, while the catalytic efficiencies kcat/Km decreased from 0.41 s(-1)/ μM (native enzyme) to 0.21 and 0.33 s(-1)/μM for Thc_Cut1+PBM and Thc_Cut1+CBM, respectively. The fusion enzymes were active both on the insoluble PET model substrate bis(benzoyloxyethyl) terephthalate (3PET) and on PET although the hydrolysis pattern was differed when compared to Thc_Cut1. Enhanced adsorption of the fusion enzymes was visible by chemiluminescence after incubation with a 6xHisTag specific horseradish peroxidase (HRP) labeled probe. Increased adsorption to PET by the fusion enzymes was confirmed with Quarz Crystal Microbalance (QCM-D) analysis and indeed resulted in enhanced hydrolysis activity (3.8× for Thc_Cut1+CBM) on PET, as quantified, based on released mono/oligomers.

  20. UPDATE ON MECHANICAL ANALYSIS OF MONOLITHIC FUEL PLATES

    Energy Technology Data Exchange (ETDEWEB)

    D. E. Burkes; F. J. Rice; J.-F. Jue; N. P. Hallinan

    2008-03-01

    Results on the relative bond strength of the fuel-clad interface in monolithic fuel plates have been presented at previous RRFM conferences. An understanding of mechanical properties of the fuel, cladding, and fuel / cladding interface has been identified as an important area of investigation and quantification for qualification of monolithic fuel forms. Significant progress has been made in the area of mechanical analysis of the monolithic fuel plates, including mechanical property determination of fuel foils, cladding processed by both hot isostatic pressing and friction bonding, and the fuel-clad composite. In addition, mechanical analysis of fabrication induced residual stress has been initiated, along with a study to address how such stress can be relieved prior to irradiation. Results of destructive examinations and mechanical tests are presented along with analysis and supporting conclusions. A brief discussion of alternative non-destructive evaluation techniques to quantify not only bond quality, but also bond integrity and strength, will also be provided. These are all necessary steps to link out-of-pile observations as a function of fabrication with in-pile behaviours.