Science.gov

Sample records for computer cathode ray

  1. Diagnostic performance of liquid crystal and cathode-ray-tube monitors in brain computed tomography.

    PubMed

    Pärtan, Gerald; Mayrhofer, Rudolf; Urban, Michael; Wassipaul, Manfred; Pichler, Ludwig; Hruby, Walter

    2003-10-01

    The aim of this study was to evaluate feasibility of reporting brain CT examinations on liquid crystal display (LCD) flat-screen monitors vs state-of-the-art cathode-ray-tube (CRT) monitors. Ninety-five brain CT examinations of 95 patients were displayed on Picture archiving and communications system (PACS) workstations equipped either with a dedicated medical imaging LCD colour monitor or on a high-resolution CRT which is used for routine reporting of CT, MRI and digital radiography images in our institution. Fifty cases were negative and 45 cases were positive for early brain infarction (EBI), the latter being defined by a combination of one or more signs: dense artery; hypodensity of brain parenchyma; and local brain swelling verified by control scans. Ten radiologists had to rate presence or absence of EBI on a five-point scale. Ratings were evaluated by CORROC2 ROC software and areas under the ROC curve (A(z)) were computed. Significance of differences between the two viewing conditions were evaluated with Wilcoxon test. Mean A(z) of the ten observers was 0.7901 with LCD vs 0.7695 with CRT which did not show statistical significance (p=0.2030). In the setting investigated, reporting of CT studies from high-performance LCD monitors seems feasible without significant detriment to diagnostic performance.

  2. Diagnostic usefulness of chest computed radiography--film versus cathode-ray tube images.

    PubMed

    Ishigaki, T; Sakuma, S; Endo, T; Ikeda, M

    1995-02-01

    Seventy-one plain chest images obtained by computed radiography (CR) with an imaging plate were interpreted on film and two kinds of cathode-ray tube (CRT) monitors installed separately at two facilities (1,024 x 1,536 pixels, 8 bits, and 1,024 x 1,280 pixels, 10 bits) by 20 radiologists and four chest internists. The clinical categories of these 71 cases included pulmonary nodules and interstitial abnormalities. Image reading sessions were held over a total of 4 days, ie, 2 days and then another 2 days, 3 weeks later. Twenty-four observers formed four groups with six members each. Two groups read either films or CRT images at one of the two facilities. In the second experiment, 26 of 71 images were compressed at 10:1, 19 of 71 were compressed at 20:1, and 26 were not compressed. Analyses of the areas under the receiver-operating characteristic curves showed no significant differences in detection of pulmonary abnormalities between film and CRT. In detecting interstitial pulmonary abnormalities, film was more sensitive than CRT monitor. There were no significant differences in observers' performances between the two different kinds of CRT workstation. Subjective evaluation of image quality showed that images irreversibly compressed to the ratios of 10:1 and 20:1 were inferior to original images. Although further considerations are needed with regard to spatial resolution requirements, image processing, and image compression, the utilization of CR CRT image as a substitute for CR film image will be possible.

  3. Composite Cathode-Ray Tube

    NASA Technical Reports Server (NTRS)

    Gangal, Mukund D.

    1988-01-01

    Proposed composite cathode-ray tube consists of rectangular array of cathode-ray tubes joined at edges, sharing common vacuum. Each electron gun generates independent image on portion of screen. Composite tube operates most advantageously under digital control to make available several display modes. Brightness and resolution of large images increased. Useful for classroom presentations, conferences, and the like.

  4. Comparison of a cathode-ray-tube and film for display of computed radiographic images.

    PubMed

    Cook, L T; Cox, G G; Insana, M F; McFadden, M A; Hall, T J; Gaborski, R S; Lure, F Y

    1998-07-01

    The goal of the study was to compare a cathode-ray-tube (CRT) digital display with film by using task-dependent image quality assessment methods. Contrast-detail analysis was utilized. Human observers performed a simple detection task, specifically, detecting a pillbox target in a uniform Poisson field, using either film or a digital display that employed a CRT monitor. Observers performed equally well on both film and CRT when the window settings of the digital display were established subjectively by a radiologist. Changing the window settings of the digital display to match the average background luminance of a film-illuminator combination decreased the luminance contrast of the targets and observer performance was reduced, though these effects were probably not linked. The "gold standard" film had lower luminance contrast than the CRT displayed images, yet observer performance was never lower for film than for the CRT. Therefore we concluded that luminance contrast was not a limiting factor for observer performance in this study. The CRT monitor changed fairly rapidly after it was calibrated. During a period of six months the gamma of the display increased from 1.82 to 2.42 and the maximum luminance decreased from 319 to 228 cd/m2. Low luminance output demonstrated a larger percentage decrease (approximately equal to 85%) than high luminance output (approximately equal to 29%) over the same time period. These observations suggest that standard window settings should be reviewed from time to time to ensure that the display is used optimally. No special look-up table setup such as perceptual linearization was used.

  5. High contrast cathode ray tube

    NASA Technical Reports Server (NTRS)

    Lisovicz, E. J.; Catlaw, T. G. (Inventor)

    1971-01-01

    A layer of material is described, which contains fine grains of phosphor material stimulated by electrons to produce visible radiation. The layer, which also contains fine grains of cobalt oxide, is deposited on the glass screen of a cathode ray tube to provide high contrast, by absorbing most of the visible radiation which is directed to the layer through the screen, while not materially affecting the visible light which the phosphor material produces in response to the electron stimulation.

  6. Look Into My Crystal Cathode Ray Tube: Computer Models Make Annual Giving Predictions Easy.

    ERIC Educational Resources Information Center

    McCaskey, Cynthia Gelhard; Dunn, John A., Jr.

    1983-01-01

    Wesleyan University's imaginative use of computer programing helped project into the future and consider alternative fund-raising methods. The process of planning the model and its use in assessing three program options are outlined, and the computer method's usefulness in motivating development staff is emphasized. (MSE)

  7. Leaching of lead from computer printed wire boards and cathode ray tubes by municipal solid waste landfill leachates.

    PubMed

    Jang, Yong-Chul; Townsend, Timothy G

    2003-10-15

    The proper management of discarded electronic devices (E-waste) is an important issue for solid waste professionals because of the magnitude of the waste stream and because these devices often contain a variety of toxic metals (e.g., lead). While recycling of E-waste is developing, much of this waste stream is disposed in landfills. Leaching tests are frequently used to characterize the potential of a solid waste to leach when disposed in a landfill. In the United States, the Toxicity Characteristic Leaching Procedure (TCLP) is used to determine whether a solid waste is a hazardous waste by the toxicity characteristic. The TCLP is designed to simulate worse-case leaching in a landfill environment where the waste is co-disposed with municipal solid waste (MSW). While the TCLP is a required analysis from a regulatory perspective, the leachate concentrations measured may not accurately reflect the concentrations observed under typical landfill conditions. Another method that can be performed to assess the degree a pollutant might leach from a waste in a landfill is to use actual landfill leachate as the leaching solution. In this study, two lead-containing components found in electronic devices (printed wire boards from computers and cathode ray tubes from computers and televisions) were leached using the TCLP and leachates from 11 Florida landfills. California's Waste Extraction Test (WET) and the Synthetic Precipitation Leaching Procedure were also performed. The results indicated that the extractions using MSW landfill leachates resulted in lower lead concentrations than those by the TCLP. The pH of the leaching solution and the ability of the organic acids in the TCLP and WET to complex with the lead are factors that regulate the amount of lead leached.

  8. Depression cathode structure for cathode ray tubes having surface smoothness and method for producing same

    SciTech Connect

    Rychlewski, T.V.

    1984-10-23

    Depression cathode structures for cathode ray tubes are produced by dispensing liquid cathode material into the depression of a metallic supporting substrate, removing excess cathode material by passing a doctor blade across the substrate surface and over the depression, and drying the cathode layer to a substantially immobile state. The cathode layer may optionally be further shaped prior to substantially complete drying thereof.

  9. Time-shared Cathode Ray Tube

    NASA Technical Reports Server (NTRS)

    Herndon, E. S.

    1969-01-01

    Time-shared cathode tube provides high quality display at low cost display stations which utilize television moniters. It updates a cluster of graphic displays from a computer and is useful in systems not equipped for graphics time-sharing.

  10. Cathode-ray tube displays for medical imaging.

    PubMed

    Keller, P A

    1990-02-01

    This paper will discuss the principles of cathode-ray tube displays in medical imaging and the parameters essential to the selection of displays for specific requirements. A discussion of cathode-ray tube fundamentals and medical requirements is included.

  11. Luminescent screen composition for cathode ray tubes

    NASA Technical Reports Server (NTRS)

    Hilborn, E. H.

    1968-01-01

    Screen composition for cathode ray tubes exhibits differential color of emission as a function of beam current variation at a constant accelerating voltage. The screen consists of a mixture of phosphors which emit different hues, have different current saturation values and exhibit a nonlinear current-brightness characteristic.

  12. The characterization of waste cathode-ray tube glass.

    PubMed

    Méar, F; Yot, P; Cambon, M; Ribes, M

    2006-01-01

    New re-use applications are needed to address the relatively large quantity of waste electronic products generated in the world. Cathode-ray tubes (CRTs) from computer monitors and TV sets are a large component of such waste. The three glass components of CRTs are the funnel, panel and neck, which are produced by various manufacturers and are now collected by asset-recovery centres. In this paper, we characterize waste funnel and panel glass from dismantled cathode-ray tubes with a view to assisting the development of new re-use applications. The heavy metal (lead, barium, and strontium) content of such glass represents an acute risk to the environment. Our results of the chemical composition for different kinds of waste CRT glass including black & white and color CRTs show that CRT glass from different producers have generally similar chemical compositions. In particular, the compositions of funnel and panel black & white CRT glass are similar, but are different to those of panel and funnel color CRT glass. We also measured the following specific properties of each type of CRT glass: density, glass transition temperature, and linear coefficient of thermal expansion. It was found that the coefficients of thermal expansion of CRT glass do not vary with their composition. In contrast, the measured densities and glass transition temperatures do vary with composition. On the basis of our experimental data and data found in the literature, we outline the main properties of several waste CRT glass currently in circulation. The aim of this study was to provide the data required to determine if this kind of waste could be entirely (or partially) re-used and to aid the search for promising methods of treatment.

  13. The characterization of waste cathode-ray tube glass.

    PubMed

    Méar, F; Yot, P; Cambon, M; Ribes, M

    2006-01-01

    New re-use applications are needed to address the relatively large quantity of waste electronic products generated in the world. Cathode-ray tubes (CRTs) from computer monitors and TV sets are a large component of such waste. The three glass components of CRTs are the funnel, panel and neck, which are produced by various manufacturers and are now collected by asset-recovery centres. In this paper, we characterize waste funnel and panel glass from dismantled cathode-ray tubes with a view to assisting the development of new re-use applications. The heavy metal (lead, barium, and strontium) content of such glass represents an acute risk to the environment. Our results of the chemical composition for different kinds of waste CRT glass including black & white and color CRTs show that CRT glass from different producers have generally similar chemical compositions. In particular, the compositions of funnel and panel black & white CRT glass are similar, but are different to those of panel and funnel color CRT glass. We also measured the following specific properties of each type of CRT glass: density, glass transition temperature, and linear coefficient of thermal expansion. It was found that the coefficients of thermal expansion of CRT glass do not vary with their composition. In contrast, the measured densities and glass transition temperatures do vary with composition. On the basis of our experimental data and data found in the literature, we outline the main properties of several waste CRT glass currently in circulation. The aim of this study was to provide the data required to determine if this kind of waste could be entirely (or partially) re-used and to aid the search for promising methods of treatment. PMID:16427267

  14. Cathode Ray Research Leading to J.J. Thomson's Discovery

    NASA Astrophysics Data System (ADS)

    Mulligan, Joseph

    1997-04-01

    This paper reviews the research on the properties and nature of cathode rays that led to the discovery of the electron by J. J. Thomson in the years 1897 - 1899. During the period from about 1870 to 1897 important research on cathode rays was carried out by William Crookes and Arthur Schuster in England, by Eugen Goldstein, Heinrich Hertz, Philipp Lenard, Emil Wiechert and Walter Kaufman in Germany, and by Jean Perrin in France. This research was always tedious and often inexact because fast vacuum pumps and convenient vacuum gauges did not yet exist. Still a few of these earlier researchers narrowly missed beating J. J. Thomson to the discover of the electron.

  15. Multilayer screen gives cathode ray tube high contrast

    NASA Technical Reports Server (NTRS)

    Bullinger, H.; Hilborn, E. H.

    1970-01-01

    Fabrication method for cathode ray tubes uses low-cost siloxane resin formulations. The resins contain sufficient methyl or phenyl groups for solubility in organic solvents. After vaporization and baking, the polymerized material is stable under vacuum and under temperatures required for tube fabrication.

  16. Management practices for end-of-life cathode ray tube glass: Review of advances in recycling and best available technologies.

    PubMed

    Iniaghe, Paschal O; Adie, Gilbert U

    2015-11-01

    Cathode ray tubes are image display units found in computer monitors and televisions. In recent years, cathode ray tubes have been generated as waste owing to the introduction of newer and advanced technologies in image displays, such as liquid crystal displays and high definition televisions, among others. Generation and subsequent disposal of end-of-life cathode ray tubes presents a challenge owing to increasing volumes and high lead content embedded in the funnel and neck sections of the glass. Disposal in landfills and open dumping are anti-environmental practices considering the large-scale contamination of environmental media by the potential of toxic metals leaching from glass. Mitigating such environmental contamination will require sound management strategies that are environmentally friendly and economically feasible. This review covers existing and emerging management practices for end-of-life cathode ray tubes. An in-depth analysis of available technologies (glass smelting, detoxification of cathode ray tube glass, lead extraction from cathode ray tube glass) revealed that most of the techniques are environmentally friendly, but are largely confined to either laboratory scale, or are often limited owing to high cost to mount, or generate secondary pollutants, while a closed-looped method is antiquated. However, recycling in cementitious systems (cement mortar and concrete) gives an added advantage in terms of quantity of recyclable cathode ray tube glass at a given time, with minimal environmental and economic implications. With significant quantity of waste cathode ray tube glass being generated globally, cementitious systems could be economically and environmentally acceptable as a sound management practice for cathode ray tube glass, where other technologies may not be applicable.

  17. Management practices for end-of-life cathode ray tube glass: Review of advances in recycling and best available technologies.

    PubMed

    Iniaghe, Paschal O; Adie, Gilbert U

    2015-11-01

    Cathode ray tubes are image display units found in computer monitors and televisions. In recent years, cathode ray tubes have been generated as waste owing to the introduction of newer and advanced technologies in image displays, such as liquid crystal displays and high definition televisions, among others. Generation and subsequent disposal of end-of-life cathode ray tubes presents a challenge owing to increasing volumes and high lead content embedded in the funnel and neck sections of the glass. Disposal in landfills and open dumping are anti-environmental practices considering the large-scale contamination of environmental media by the potential of toxic metals leaching from glass. Mitigating such environmental contamination will require sound management strategies that are environmentally friendly and economically feasible. This review covers existing and emerging management practices for end-of-life cathode ray tubes. An in-depth analysis of available technologies (glass smelting, detoxification of cathode ray tube glass, lead extraction from cathode ray tube glass) revealed that most of the techniques are environmentally friendly, but are largely confined to either laboratory scale, or are often limited owing to high cost to mount, or generate secondary pollutants, while a closed-looped method is antiquated. However, recycling in cementitious systems (cement mortar and concrete) gives an added advantage in terms of quantity of recyclable cathode ray tube glass at a given time, with minimal environmental and economic implications. With significant quantity of waste cathode ray tube glass being generated globally, cementitious systems could be economically and environmentally acceptable as a sound management practice for cathode ray tube glass, where other technologies may not be applicable. PMID:26463115

  18. 21 CFR 870.2450 - Medical cathode-ray tube display.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Medical cathode-ray tube display. 870.2450 Section 870.2450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... cathode-ray tube display. (a) Identification. A medical cathode-ray tube display is a device...

  19. 21 CFR 870.2450 - Medical cathode-ray tube display.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Medical cathode-ray tube display. 870.2450 Section 870.2450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... cathode-ray tube display. (a) Identification. A medical cathode-ray tube display is a device...

  20. 21 CFR 870.2450 - Medical cathode-ray tube display.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical cathode-ray tube display. 870.2450 Section 870.2450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... cathode-ray tube display. (a) Identification. A medical cathode-ray tube display is a device...

  1. 21 CFR 870.2450 - Medical cathode-ray tube display.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Medical cathode-ray tube display. 870.2450 Section 870.2450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... cathode-ray tube display. (a) Identification. A medical cathode-ray tube display is a device...

  2. 21 CFR 870.2450 - Medical cathode-ray tube display.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Medical cathode-ray tube display. 870.2450 Section 870.2450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... cathode-ray tube display. (a) Identification. A medical cathode-ray tube display is a device...

  3. Cathode ray tube glass recycling: an example of clean technology.

    PubMed

    Andreola, Fernanda; Barbieri, Luisa; Corradi, Anna; Lancellotti, Isabella

    2005-08-01

    In this study the use of 'cleaned' end of life (EOL) cathode ray tube (CRT) glass as a raw material in ceramic glazes is described. At present, the recycling and industrial utilization of CRT, a glass material from TV and computer sets, is a subject of intense research with particular regard to the so-called open-loop recycling, namely cycles different from that of the origin. However, the use of CRT glass as a secondary raw material is strictly related to the demand of high-quality raw material. The good preliminary results reached by introducing clean TV and PC monitor panel and cone glass into ceramic glaze formulations pushed research toward the setting-up of a base glaze that is exploitable for the production of pigmented, silk-screened and flame-hardened glazes (products used industrially for coating floor tiles). The aesthetic and chemical characterization of the tiles glazed by this product showed an extremely similar behaviour to originals that did not contain CRT glass. The good technical results achieved have been supported by the life cycle assessment analysis, which has demonstrated a reduction of the environmental impact of the CRT glass-containing ceramic glaze with respect to the standard one.

  4. Computer modeling of cathodic protection on risers/tendons

    SciTech Connect

    Osvoll, H.; Gartland, P.O.; Thomason, W.H.

    1995-02-01

    Computer modeling is gaining popularity in the design and verification of cathodic protection (CP) systems for offshore structures. The work presented in this article expands the use of CP simulation to consider the metallic electrical resistance of risers/tendons used with tension leg platforms where anodes are mounted on the hull or subsea structure. The SEACORR/CP computer system was used to perform a parametric study to identify the limitations of CP and coatings in providing corrosion protection. The effect of using a titanium riser instead of a steel riser was also considered.

  5. Schematic displays for the Space Shuttle Orbiter multifunction cathode-ray-tube display system

    NASA Technical Reports Server (NTRS)

    Weiss, W.

    1979-01-01

    A standardized procedure for developing cathode ray tube displayed schematic diagrams. The displaying of Spacelab information on the space shuttle orbiter multifunction cathode ray tube display system is used to illustrate this procedure. Schematic displays with the equivalent tabular displays are compared.

  6. Liquid jet target x-ray tube with field emission cathode

    NASA Astrophysics Data System (ADS)

    Heid, Oliver; Polikhov, Stepan; Karpinskiy, Gennadiy; Geisler, Andreas; Bondarenko, Taras; Botyachkova, Alexandra; Frolov, Sergey; Ivanov, Vladislav

    2015-08-01

    We introduce first results of our research in a promising approach for micro focal x-ray generation. The approach combines the use of liquid metal jet target as anode and carbon based nanostructures as field emission cathode. Results of metal jet break-up CFD simulation and cold cathode performance tests are described. The planned experimental program is discussed herein as well.

  7. Investigation on emission characteristics of metal-ceramic cathode applied to industrial X-ray diode.

    PubMed

    Xun, Ma; Jianqiang, Yuan; Hongwei, Liu; Hongtao, Li; Lingyun, Wang; Ping, Jiang

    2016-06-01

    The industrial x-ray diode with high impedance configuration is usually adopted to generate repetitive x-ray, but its performance would be worsened due to lower electric field on the cathode of diode when a voltage of several hundreds of kV is applied. To improve its performance, a novel metal-ceramic cathode is proposed in this paper. Key factors (width, relative permittivity of ceramic, and so on) affecting electric field distribution on triple points are analyzed by electrostatic field calculation program, so as to optimize the design of this novel cathode. Experiments are done to study the characteristics including emission current of cathode, diode voltage duration, diode mean dynamic impedance, and diode impedance drop velocity within diode power duration. The results show that metal-ceramic cathode could improve diode performance by enhancing emission current and stabling impedance; the impedance drop velocity of diode with spoke-shaped metal-ceramic cathode was reduced to -5 Ω ns(-1) within diode power duration, comparing to -15 Ω ns(-1) with metal foil cathode. PMID:27370441

  8. Investigation on emission characteristics of metal-ceramic cathode applied to industrial X-ray diode.

    PubMed

    Xun, Ma; Jianqiang, Yuan; Hongwei, Liu; Hongtao, Li; Lingyun, Wang; Ping, Jiang

    2016-06-01

    The industrial x-ray diode with high impedance configuration is usually adopted to generate repetitive x-ray, but its performance would be worsened due to lower electric field on the cathode of diode when a voltage of several hundreds of kV is applied. To improve its performance, a novel metal-ceramic cathode is proposed in this paper. Key factors (width, relative permittivity of ceramic, and so on) affecting electric field distribution on triple points are analyzed by electrostatic field calculation program, so as to optimize the design of this novel cathode. Experiments are done to study the characteristics including emission current of cathode, diode voltage duration, diode mean dynamic impedance, and diode impedance drop velocity within diode power duration. The results show that metal-ceramic cathode could improve diode performance by enhancing emission current and stabling impedance; the impedance drop velocity of diode with spoke-shaped metal-ceramic cathode was reduced to -5 Ω ns(-1) within diode power duration, comparing to -15 Ω ns(-1) with metal foil cathode.

  9. Rigid indented cylindrical cathode for X-ray tube

    DOEpatents

    Hudgens, Claude R.

    1985-01-01

    A cathode assembly for a vacuum tube includes a wire filament, a straight bular anode parallel to and surrounding the wire filament, and insulating spacers for rigidly fastening the filament with respect to the anode, and with one side of the anode indented or flattened such that only one portion of the anode is heated to emitting temperatures by the filament.

  10. Hollow cathodes as electron emitting plasma contactors Theory and computer modeling

    NASA Technical Reports Server (NTRS)

    Davis, V. A.; Katz, I.; Mandell, M. J.; Parks, D. E.

    1987-01-01

    Several researchers have suggested using hollow cathodes as plasma contactors for electrodynamic tethers, particularly to prevent the Shuttle Orbiter from charging to large negative potentials. Previous studies have shown that fluid models with anomalous scattering can describe the electron transport in hollow cathode generated plasmas. An improved theory of the hollow cathode plasmas is developed and computational results using the theory are compared with laboratory experiments. Numerical predictions for a hollow cathode plasma source of the type considered for use on the Shuttle are presented, as are three-dimensional NASCAP/LEO calculations of the emitted ion trajectories and the resulting potentials in the vicinity of the Orbiter. The computer calculations show that the hollow cathode plasma source makes vastly superior contact with the ionospheric plasma compared with either an electron gun or passive ion collection by the Orbiter.

  11. Low-power-loss and high voltage X-ray tube with graphite nanospines cold cathode

    NASA Astrophysics Data System (ADS)

    Jyouzuka, Atsuo; Koike, Takayoshi; Nakamura, Tomonori; Onizuka, Yoshihiro; Mimura, Hidenori

    2011-12-01

    We report a low-power-loss and high voltage X-ray tubes with a graphite nanospines (GNS) cold cathode. The cathode is encapsulated in a glass tube having a Beryllium window with a Tantalum film to generate X-rays. The internal tube pressure was below 10-7 Pa and a tube current exceeding 1 mA at a tube voltage of 22.9 kV was observed in the fabricated X-ray tube. The tube current dispersion, defined as standard deviation/mean (σ/mean), was relatively small at 2.4%. An X-ray radiation dose rate exceeding 5 Sv/h was obtained from the X-ray tube and the radiation dose rate dispersion was also small (σ/mean=0.3%). As an application of the X-ray tube, we demonstrated radiography for the rapid inspection of organic products.

  12. Utilization of recycled glass derived from cathode ray tube glass as fine aggregate in cement mortar.

    PubMed

    Ling, Tung-Chai; Poon, Chi-Sun

    2011-08-30

    Rapid advances in the electronic industry led to an excessive amount of early disposal of older electronic devices such as computer monitors and old televisions (TV) before the end of their useful life. The management of cathode ray tubes (CRT), which have been a key component in computer monitors and TV sets, has become a major environmental problem worldwide. Therefore, there is a pressing need to develop sustainable alternative methods to manage hazardous CRT glass waste. This study assesses the feasibility of utilizing CRT glass as a substitute for natural aggregates in cement mortar. The CRT glass investigated was an acid-washed funnel glass of dismantled CRT from computer monitors and old TV sets. The mechanical properties of mortar mixes containing 0%, 25%, 50%, 75% and 100% of CRT glass were investigated. The potential of the alkali-silica reaction (ASR) and leachability of lead were also evaluated. The results confirmed that the properties of the mortar mixes prepared with CRT glass was similar to that of the control mortar using sand as fine aggregate, and displayed innocuous behaviour in the ASR expansion test. Incorporating CRT glass in cement mortar successfully prevented the leaching of lead. We conclude that it is feasible to utilize CRT glass in cement mortar production.

  13. Utilization of recycled glass derived from cathode ray tube glass as fine aggregate in cement mortar.

    PubMed

    Ling, Tung-Chai; Poon, Chi-Sun

    2011-08-30

    Rapid advances in the electronic industry led to an excessive amount of early disposal of older electronic devices such as computer monitors and old televisions (TV) before the end of their useful life. The management of cathode ray tubes (CRT), which have been a key component in computer monitors and TV sets, has become a major environmental problem worldwide. Therefore, there is a pressing need to develop sustainable alternative methods to manage hazardous CRT glass waste. This study assesses the feasibility of utilizing CRT glass as a substitute for natural aggregates in cement mortar. The CRT glass investigated was an acid-washed funnel glass of dismantled CRT from computer monitors and old TV sets. The mechanical properties of mortar mixes containing 0%, 25%, 50%, 75% and 100% of CRT glass were investigated. The potential of the alkali-silica reaction (ASR) and leachability of lead were also evaluated. The results confirmed that the properties of the mortar mixes prepared with CRT glass was similar to that of the control mortar using sand as fine aggregate, and displayed innocuous behaviour in the ASR expansion test. Incorporating CRT glass in cement mortar successfully prevented the leaching of lead. We conclude that it is feasible to utilize CRT glass in cement mortar production. PMID:21705136

  14. A Century-Old Question: Does a Crookes Paddle Wheel Cathode Ray Tube Demonstrate That Electrons Carry Momentum?

    ERIC Educational Resources Information Center

    Humphrey, T. E.; Calisa, Vaishnavi

    2014-01-01

    In 1879, in the midst of the debate between English and continental scientists about the nature of cathode rays, William Crookes conducted an experiment in which a small mill or "paddle wheel" was pushed along tracks inside a cathode ray tube (CRT) (similar to that shown in Fig. 1) when connected to a high-voltage induction coil. Crookes…

  15. 40 CFR 261.41 - Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse. 261.41 Section 261.41 Protection of... Tubes (CRTs) Exported for Reuse. (a) Persons who export used, intact CRTs for reuse must send a one-time... forth as follows: § 261.41 Notification and Recordkeeping for Used, Intact Cathode Ray Tubes...

  16. Computer controlled techniques for high emission density mapping of thermionic cathodes

    NASA Astrophysics Data System (ADS)

    Gibson, J. W.; Thomas, R. E.

    1985-12-01

    Some of the techniques commonly used (e.g. SLEEP and thermionic emission microscope) for measuring emission or work function uniformity of thermionic cathode surfaces require the use of very low or near zero current densities, thus the cathode is characterized at current densities and temperatures much lower than that of a normally operating cathode. The system reported on here uses a high voltage pulse technique and is capable of measuring emission densities in the range 1 to 80 A/cm 2 at normal cathode operating temperatures. The cathode surface is scanned with an anode having a 0.025 mm aperture whose position is controlled by computer operated stepping motors. The current through the aperture to a collector electrode is measured using a sample-and-hold amplifier. Pulsing and sampling are computer synchronized with the scanning, and data for each pulse are accumulated and can be processed and displayed in several ways using the computer, including a detailed "three-dimensional" map of either the electron emission density or work function variations. The entire surface of the cathode or any portion of it can be mapped in steps as small as 0.001 mm (1μm), but typically steps of 5-100 μm were used. Measurements are presented illustrating the uniformity or nonuniformity of the electron emission densities and work functions for type-B and type-M cathodes.

  17. Computational study of RF micro-hollow cathode discharge

    NASA Astrophysics Data System (ADS)

    Berkane, A.; Rebiai, S.; Bouanaka, F.; Bahouh, H.

    2015-06-01

    Radiofrequency discharges can generate non-equilibrium and stable micro-plasmas without a streamer in micro-hollow cathode reactors. In this work, we present the results of a fluid model describing the mechanisms occurring in a micro-reactor in argon plasma, generated by an excitation of 13.56 MHz at high pressures (100 Torr) with and without a secondary emission of electrons. The results of the simulation improve the understanding of the effect of micro-hollow cathodes and of the influence of excited atoms in ionization and sustainment of argon discharge at low voltage (150 V). Simulation results showed that the maximum of penning ionization and stepwise ionization rates are respectively about 25% and 11% of the maximum of direct ionization rate. The metastable atom density reaches a maximum value of 1020/m3 inside the hole and have also two humps near to oppsite cathodes. Accordingly the excitation rate is significant in all the space.

  18. Field emission behavior of carbon nanotube yarn for micro-resolution X-ray tube cathode.

    PubMed

    Hwang, Jae Won; Mo, Chan Bin; Jung, Hyun Kyu; Ryu, Seongwoo; Hong, Soon Hyung

    2013-11-01

    Carbon nanotube (CNT) has excellent electrical and thermal conductivity and high aspect ratio for X-ray tube cathode. However, CNT field emission cathode has been shown unstable field emission and short life time due to field evaporation by high current density and detachment by electrostatic force. An alternative approach in this direction is the introduction of CNT yarn, which is a one dimensional assembly of individual carbon nanotubes bonded by the Van der Waals force. Because CNT yarn is composed with many CNTs, CNT yarns are expected to increase current density and life time for X-ray tube applications. In this research, CNT yarn was fabricated by spinning of a super-aligned CNT forest and was characterized for application to an X-ray tube cathode. CNT yarn showed a high field emission current density and a long lifetime of over 450 hours. Applying the CNT yarn field emitter to the X-ray tube cathode, it was possible to obtain micro-scale resolution images. The relationship between the field emission properties and the microstructure evolution was investigated and the unraveling effect of the CNT yarn was discussed. PMID:24245260

  19. The determination of iron, titanium, and nickel in Apollo 14 samples by cathode ray polarography.

    NASA Technical Reports Server (NTRS)

    Maienthal, E. J.

    1972-01-01

    Methods have been developed and applied to the determination of iron, titanium, and nickel in Apollo 14 fine soil and rock by differential cathode ray polarography on the same sample. A 5 mg sample was sufficient for the determination of all 3 elements. Iron and titanium were determined either directly or after cupferron separation. Nickel was determined after dimethylglyoxime separation.

  20. Comparison of electromechanical and cathode-ray-tube display mediums for an instrument approach display

    NASA Technical Reports Server (NTRS)

    Abbott, T. S.

    1979-01-01

    The effect on pilot performance of replacing a single electromechanical display with similar cathode-ray-tube displays was studied. The effects of dimensionality, color, and shading were evaluated with respect to the pilot's ability to interpret and respond to displayed information.

  1. Field emission behavior of carbon nanotube yarn for micro-resolution X-ray tube cathode.

    PubMed

    Hwang, Jae Won; Mo, Chan Bin; Jung, Hyun Kyu; Ryu, Seongwoo; Hong, Soon Hyung

    2013-11-01

    Carbon nanotube (CNT) has excellent electrical and thermal conductivity and high aspect ratio for X-ray tube cathode. However, CNT field emission cathode has been shown unstable field emission and short life time due to field evaporation by high current density and detachment by electrostatic force. An alternative approach in this direction is the introduction of CNT yarn, which is a one dimensional assembly of individual carbon nanotubes bonded by the Van der Waals force. Because CNT yarn is composed with many CNTs, CNT yarns are expected to increase current density and life time for X-ray tube applications. In this research, CNT yarn was fabricated by spinning of a super-aligned CNT forest and was characterized for application to an X-ray tube cathode. CNT yarn showed a high field emission current density and a long lifetime of over 450 hours. Applying the CNT yarn field emitter to the X-ray tube cathode, it was possible to obtain micro-scale resolution images. The relationship between the field emission properties and the microstructure evolution was investigated and the unraveling effect of the CNT yarn was discussed.

  2. The Fine-Beam Cathode-Ray Tube and the Observant and Enquiring Student, Part 8.

    ERIC Educational Resources Information Center

    Webb, John le P.

    1985-01-01

    This final article in the series on the fine-beam cathode-ray tube presents: (1) additional investigations; (2) an alternative method for the electron e/m and synchrotron radiation; and (3) two challenges to students (in a dialogue format) together with a lengthy discussion on synchrotron radiation sources. (DH)

  3. The Fine-Beam Cathode-Ray Tube and the Observant and Enquiring Student, Part 6.

    ERIC Educational Resources Information Center

    Webb, John le P.

    1984-01-01

    Describes (in the form of a hypothetical discussion between teacher and student) several demonstrations using the fine-beam cathode-ray tube. One is a demonstration of how a magnetic field can help to initiate and propagate a fine beam. (JN)

  4. The Fine-Beam Cathode-Ray Tube and the Observant and Enquiring Student - Part 1.

    ERIC Educational Resources Information Center

    Webb, John le P.

    1984-01-01

    Describes the fine-beam cathode-ray tube, explaining observed phenomena from a visual, qualitative viewpoint. Discusses the reason for the fineness of the beam and provides the theoretical basis for the observed circular shape of the beam when the Helmholtz field is applied. (JM)

  5. The Fine-Beam Cathode-Ray Tube and the Observant and Enquiring Student, Part 5.

    ERIC Educational Resources Information Center

    Webb, John le P.

    1984-01-01

    Discusses the physics of electromagnetic focussing using an imaginary dialogue between teacher and student. It is assumed that students have been introduced to the underlying theory concerning movement of a charged particle traveling with uniform speed in a magnetic field before seeing a demonstration with the fine-beam cathode-ray tube. (JN)

  6. X-ray Tube Using a Graphene Flower Cloth Field Emission Cathode

    NASA Astrophysics Data System (ADS)

    Iwai, Yusuke; Muramatsu, Kazuo; Tsuboi, Shougo; Jyouzuka, Atsuo; Nakamura, Tomonori; Onizuka, Yoshihiro; Mimura, Hidenori

    2013-10-01

    We have successfully fabricated a filament-less X-ray tube using a graphene flower cloth (GFC) field emission cathode. The GFC has numerous nanoprotrusions formed by self-standing graphene structures. The field emission current and the field enhancement factor β were 500 µA and 5600, respectively. The stability of voltage defined as a variance coefficient (σ/mean) of voltage was calculated to be 0.04% while maintaining the X-ray tube current of 300 µA. We applied our X-ray tube with the GFC field emitter to the X-ray fluorescence (XRF) analysis of stainless steel.

  7. X-ray dose estimation from cathode ray tube monitors by Monte Carlo calculation.

    PubMed

    Khaledi, Navid; Arbabi, Azim; Dabaghi, Moloud

    2015-04-01

    Cathode Ray Tube (CRT) monitors are associated with the possible emission of bremsstrahlung radiation produced by electrons striking the monitor screen. Because of the low dose rate, accurate dosimetry is difficult. In this study, the dose equivalent (DE) and effective dose (ED) to an operator working in front of the monitor have been calculated using the Monte Carlo (MC) method by employing the MCNP code. The mean energy of photons reaching the operator was above 17 keV. The phantom ED was 454 μSv y (348 nSv h), which was reduced to 16 μSv y (12 nSv h) after adding a conventional leaded glass sheet. The ambient dose equivalent (ADE) and personal dose equivalent (PDE) for the head, neck, and thorax of the phantom were also calculated. The uncertainty of calculated ED, ADE, and PDE ranged from 3.3% to 10.7% and 4.2% to 14.6% without and with the leaded glass, respectively.

  8. Exposure to hazardous substances in Cathode Ray Tube (CRT) recycling sites in France

    SciTech Connect

    Lecler, Marie-Thérèse Zimmermann, François; Silvente, Eric; Clerc, Frédéric; Chollot, Alain; Grosjean, Jérôme

    2015-05-15

    Highlights: • Chemical risks were assessed in the nine cathode ray tube screens recycling facilities. • The main hazardous agents are dust containing lead, cadmium, barium and yttrium. • Exposure and pollutant levels are described for different operations and processes. • All the operations and processes are concerned by significant levels of pollutants. • We suggest recommendations to reduce chemical risk. - Abstract: The Waste Electrical and Electronic Equipment (WEEE) or e-waste recycling sector has grown considerably in the last fifteen years due to the ever shorter life cycles of consumables and an increasingly restrictive policy context. Cathode Ray Tubes (CRTs) from used television and computer screens represent one of the main sources of e-waste. CRTs contain toxic materials such as lead, cadmium, barium, and fluorescent powders which can be released if recycling of CRTs is not appropriate. Exposure to these harmful substances was assessed in nine workshops where CRT screens are treated. Particulate exposure levels were measured using a gravimetric method and metals were analysed by plasma emission spectrometry. The maximum levels of worker exposure were 8.8 mg/m{sup 3}, 1504.3 μg/m{sup 3}, 434.9 μg/m{sup 3}, 576.3 μg/m{sup 3} and 2894.3 μg/m{sup 3} respectively for inhalable dust, barium, cadmium, lead and yttrium. The maximum levels of airborne pollutants in static samples were 39.0 mg/m{sup 3}, 848.2 μg/m{sup 3}, 698.4 μg/m{sup 3}, 549.3 μg/m{sup 3} and 3437.9 μg/m{sup 3} for inhalable dust, barium, cadmium, lead and yttrium. The most harmful operations were identified, and preventive measures for reducing the chemical risk associated with screen recycling were proposed. Workplace measurements were used to define recommendations for reducing the chemical risks in CRT screens recycling facilities and for promoting the design and development of “clean and safe” processes in emerging recycling channels.

  9. Cathode ray tube (CRT) recycling: current capabilities in China and research progress.

    PubMed

    Xu, Qingbo; Li, Guangming; He, Wenzhi; Huang, Juwen; Shi, Xiang

    2012-08-01

    It is estimated that approximately 6,000,000 scrap TVs and 10,000,000 personal computers are generated each year in China. Cathode ray tubes (CRTs) from these machines consist of 85% glass (65% panel, 30% funnel and 5% neck glass). The leaded glass (funnel-24%, neck-30%) may seriously pollute the environment if it is not properly disposed of. In this paper, the past, current and future status of CRT dismantling technologies as well as the CRT glass recycling situation in China are presented and discussed. Recycling technology for waste CRTs in China is still immature. While the conventional CRT dismantling technologies have disadvantages from both economic and environmental viewpoints, some of the new and emerging treatments such as automatic optical sorting facilities that have been applied in developed countries offer advantages, and therefore should be transferred to China in the next few years to solve the CRT pre-processing problem. Meanwhile, because the demand for CRT glass closed-loop recycling is extremely limited, the authorities should take effective measures to improve CRT glass recycling rates and to facilitate a match to local conditions. Moreover, we also provide a broad review of the research developments in recycling techniques for CRT cullet. The challenge for the future is to transfer these environmentally friendly and energy-saving technologies into practice. PMID:22542858

  10. Cathode ray tube (CRT) recycling: current capabilities in China and research progress.

    PubMed

    Xu, Qingbo; Li, Guangming; He, Wenzhi; Huang, Juwen; Shi, Xiang

    2012-08-01

    It is estimated that approximately 6,000,000 scrap TVs and 10,000,000 personal computers are generated each year in China. Cathode ray tubes (CRTs) from these machines consist of 85% glass (65% panel, 30% funnel and 5% neck glass). The leaded glass (funnel-24%, neck-30%) may seriously pollute the environment if it is not properly disposed of. In this paper, the past, current and future status of CRT dismantling technologies as well as the CRT glass recycling situation in China are presented and discussed. Recycling technology for waste CRTs in China is still immature. While the conventional CRT dismantling technologies have disadvantages from both economic and environmental viewpoints, some of the new and emerging treatments such as automatic optical sorting facilities that have been applied in developed countries offer advantages, and therefore should be transferred to China in the next few years to solve the CRT pre-processing problem. Meanwhile, because the demand for CRT glass closed-loop recycling is extremely limited, the authorities should take effective measures to improve CRT glass recycling rates and to facilitate a match to local conditions. Moreover, we also provide a broad review of the research developments in recycling techniques for CRT cullet. The challenge for the future is to transfer these environmentally friendly and energy-saving technologies into practice.

  11. Lead recovery from scrap cathode ray tube funnel glass by hydrothermal sulphidisation.

    PubMed

    Yuan, Wenyi; Meng, Wen; Li, Jinhui; Zhang, Chenglong; Song, Qingbin; Bai, Jianfeng; Wang, Jingwei; Li, Yingshun

    2015-10-01

    This research focused on the application of the hydrothermal sulphidisation method to separate lead from scrap cathode ray tube funnel glass. Prior to hydrothermal treatment, the cathode ray tube funnel glass was pretreated by mechanical activation. Under hydrothermal conditions, hydroxyl ions (OH(-)) were generated through an ion exchange reaction between metal ions in mechanically activated funnel glass and water, to accelerate sulphur disproportionation; no additional alkaline compound was needed. Lead contained in funnel glass was converted to lead sulphide with high efficiency. Temperature had a significant effect on the sulphidisation rate of lead in funnel glass, which increased from 25% to 90% as the temperature increased from 100 °C to 300 °C. A sulphidisation rate of 100% was achieved at a duration of 8 h at 300 °C. This process of mechanical activation and hydrothermal sulphidisation is efficient and promising for the treatment of leaded glass.

  12. Threshold and efficiency of a laser cathode-ray tube at room temperature

    SciTech Connect

    Kozlovskii, Vladimir I; Popov, Yurii M

    2003-01-31

    The main factors determining the lasing threshold and efficiency of a laser cathode-ray tube at room temperature are considered. Recent achievements obtained by using laser screens made of the II - VI compound single crystals are discussed. It is shown that multilayer heterostructures allow the reduction in the lasing threshold by several times. (special issue devoted to the 80th anniversary of academician n g basov's birth)

  13. Evaluation of biopolymer-modified concrete systems for disposal of cathode ray tube glass.

    PubMed

    Kim, Daeik; Petrisor, loana G; Yen, Teh Fu

    2005-07-01

    Cathode ray tubes (CRTs) from computer monitors and television sets, which contain significantly high percentage of lead (Pb) by weight, represent an enormous and growing hazardous waste problem in the United States and worldwide. As a result, new technologies are needed to cope with current CRT waste stream and increased hazard and build new markets for its recycled components, developing commercially viable concrete composites, as well as minimizing CRT disposal problems. In this study, commercially available biopolymers, such as xanthan gum, guar gum, and chitosan, were used to encapsulate CRT glass waste, reducing the Pb leachability. The biopolymers utilized contain a number of useful functional groups, such as carboxyl (xanthan), hydroxyl (guar), and amino groups (chitosan), which play important roles in binding and stabilizing Pb onto concrete structures. The use of biopolymers in concrete systems can create a stable interpenetrating cross-linking composite that will last for many years. Results from these new composites show 30% higher compressive strength than standard concrete and a sharp decrease in lead leachability from several thousand milligrams per liter initially to an amount of three-tenths milligrams per liter or lower values (much lower than the U.S. Environment Protection Agency standard for hazardous waste of 5 mg/L by the toxicity characteristic leaching procedure test), and for some of the composites leachability is below even the standard for drinking water. This efficient and cost-effective CRT-biopolymer-concrete composite is a new class of biopolymer-modified material that can potentially perform a significant role in relieving the current CRT issue.

  14. Exposure to hazardous substances in Cathode Ray Tube (CRT) recycling sites in France.

    PubMed

    Lecler, Marie-Thérèse; Zimmermann, François; Silvente, Eric; Clerc, Frédéric; Chollot, Alain; Grosjean, Jérôme

    2015-05-01

    The Waste Electrical and Electronic Equipment (WEEE) or e-waste recycling sector has grown considerably in the last fifteen years due to the ever shorter life cycles of consumables and an increasingly restrictive policy context. Cathode Ray Tubes (CRTs) from used television and computer screens represent one of the main sources of e-waste. CRTs contain toxic materials such as lead, cadmium, barium, and fluorescent powders which can be released if recycling of CRTs is not appropriate. Exposure to these harmful substances was assessed in nine workshops where CRT screens are treated. Particulate exposure levels were measured using a gravimetric method and metals were analysed by plasma emission spectrometry. The maximum levels of worker exposure were 8.8mg/m(3), 1504.3μg/m(3), 434.9μg/m(3), 576.3μg/m(3) and 2894.3μg/m(3) respectively for inhalable dust, barium, cadmium, lead and yttrium. The maximum levels of airborne pollutants in static samples were 39.0mg/m(3), 848.2μg/m(3), 698.4μg/m(3), 549.3μg/m(3) and 3437.9μg/m(3) for inhalable dust, barium, cadmium, lead and yttrium. The most harmful operations were identified, and preventive measures for reducing the chemical risk associated with screen recycling were proposed. Workplace measurements were used to define recommendations for reducing the chemical risks in CRT screens recycling facilities and for promoting the design and development of "clean and safe" processes in emerging recycling channels.

  15. What monitor can replace the cathode-ray tube for visual stimulation to elicit multifocal electroretinograms?

    PubMed

    Matsumoto, Celso Soiti; Shinoda, Kei; Matsumoto, Harue; Seki, Keisuke; Nagasaka, Eiichiro; Iwata, Takeshi; Mizota, Atsushi

    2014-01-01

    To compare a conventional cathode-ray tube (CRT) screen to organic light-emitting diode (OLED) and liquid crystal display (LCD) screens as visual stimulators to elicit multifocal electroretinograms (mfERGs), mfERGs were recorded from seven eyes of seven healthy volunteers (21 ± 2 years). The mfERGs elicited by a conventional CRT screen (S710, Compaq Computer Co.) were compared to those elicited by a studio-grade master OLED monitor (PVM-1741, Sony, Japan) and a conventional LCD (S1721, Flexscan, Eizo Nanao Corp., Japan). The luminance changes of each monitor were measured with a photodiode. CRT, OLED, and LCD screens with a frame frequency of 60 Hz were studied. A hexagonal stimulus array with 61 stimulus elements was created on each monitor. The serial white stimuli of the OLED screen at 60 Hz did not fuse, and that of the LCD screens fused. The amplitudes of P1 and P2 of the first-order kernels of the mfERGs were not significantly different from those elicited by the CRT and OLED screens, and the P1 amplitude of the first-order kernel elicited by the LCD stimuli was significantly smaller than that elicited by the CRT in all the groups of the averaged hexagonal elements. The implicit times were approximately 10 ms longer in almost all components elicited by the LCD screen compared to those elicited by the CRT screen. The mfERGs elicited by monitors other than the CRT should be carefully interpreted, especially those elicited by LCD screens. The OLED had good performance, and we conclude that it can replace the CRT as a stimulator for mfERGs; however, a collection of normative data is recommended.

  16. Colored focal visual evoked potentials by cathode ray tube versus scanning laser ophthalmoscope.

    PubMed

    Rigaudière, F; Le Gargasson, J F; Guez, J E; Grall, Y

    1993-01-01

    We compared the focal visual evoked potentials obtained in 52 young subjects with normal vision, evoked by means of three alternating black/color checkerboards generated by a trichromic cathode ray tube (dominant wavelength, 514 nm; colorimetric purity, 0.45) and by means of a scanning laser ophthalmoscope (argon laser beam, 514 nm; colorimetric purity, approximately 1). These three checkerboards, with an area of 3.5 degrees x 3.5 degrees (stimulating the fovea), then with an area of 3.5 degrees x 3.5 degrees with a central exclusion of 1.5 degrees x 1.5 degrees (stimulating the perifoveola) and finally with an area of 1.5 degrees x 1.5 degrees (stimulating the foveola) were presented within a field (8 degrees x 8 degrees) of homogeneous luminance of 170 cd/m2 and 1500 cd/m2, respectively. Their check sizes were 30', with a reversal temporal frequency of 0.75 Hz. The transient focal visual evoked potentials recorded with these three stimuli generated by the two types of stimulators were clearly detected for at least 85% of subjects. Their characteristics (waveform, amplitude and culmination times of the different waves) were comparable, regardless of the stimulator used (cathode ray tube or scanning laser ophthalmoscope). These results suggest that, under these various conditions of luminance and colorimetric purity, the neurophysiologic circuits tested function in identical ways. The focal visual evoked potential signs, now clearly defined by means of stimuli generated by cathode ray tubes, therefore apparently can be applied to the focal visual evoked potential evoked by stimuli generated by the scanning laser ophthalmoscope.

  17. Application Of Cathode-Ray Tube Technology To The Clinical Evaluation Of Visual Functions

    NASA Astrophysics Data System (ADS)

    Vernier, Francoise; Charlier, Jacques; Nguyen, Duc D.

    1988-02-01

    Cathode-ray tubes (CRTs) have many applications in the clinical evaluation of visual functions. They have been used to test visual acuity, contrast sensitivity, visual fields, and early development of vision in preverbal children. Because CRTs provide considerable flexibility for the definition of spatial and temporal components of the stimulus, their use provides an attractive solution to many visual stimulation problems. However, there are some limitations due to the scanning of the picture frame by the electron beam and also to the electron-photon conversion process. The spatial, photometric, spectral, and temporal characteristics of a specifically designed monochromatic television system are evaluated with reference to the physiological requirements of visual tests.

  18. Temperature regime of the laser screen of a cathode-ray tube

    SciTech Connect

    Kozlovskii, Vladimir I; Kumykov, Kh Kh; Malyshev, I V; Popov, Yurii M

    2002-04-30

    The temperature regime of a laser cathode-ray tube are studied upon the electron-beam raster scanning. Three main factors determining the temperature of the active region of a laser are distinguished: the adiabatic heating by the electron beam during excitation of an individual pixel, heating caused by adjacent lines, and heating averaged during previous scans, which is determined by cooling of the laser screen. The numerical estimates of the temperature rise caused by these factors are presented. The influence of the temperature of the active region on the lasing power is discussed. (lasers)

  19. Characterization of Cathode Materials for Rechargeable Lithium Batteries using Synchrotron Based In Situ X-ray Techniques

    SciTech Connect

    Yang, Xiao-Qing

    2007-05-23

    The emergence of portable telecommunication, computer equipment and ultimately hybrid electric vehicles has created a substantial interest in manufacturing rechargeable batteries that are less expensive, non-toxic, operate for longer time, small in size and weigh less. Li-ion batteries are taking an increasing share of the rechargeable battery market. The present commercial battery is based on a layered LiCoO{sub 2} cathode and a graphitized carbon anode. LiCoO{sub 2} is expensive but it has the advantage being easily manufactured in a reproducible manner. Other low cost layered compounds such as LiNiO{sub 2}, LiNi{sub 0.85}Co{sub 0.15}O{sub 2} or cubic spinels such as LiMn{sub 2}O{sub 4} have been considered. However, these suffer from cycle life and thermal stability problems. Recently, some battery companies have demonstrated a new concept of mixing two different types of insertion compounds to make a composite cathode, aimed at reducing cost and improving self-discharge. Reports clearly showed that this blending technique can prevent the decline in ·capacity caused by cycling or storage at elevated temperatures. However, not much work has been reported on the charge-discharge characteristics and phase transitions for these composite cathodes. Understanding the structure and structural changes of electrode materials during the electrochemical cycling is the key to develop better .lithium ion batteries. The successful commercialization of the· lithium-ion battery is mainly built on the advances in solid state chemistry of the intercalation compounds. Most of the progress in understanding the lithium ion battery materials has been obtained from x-ray diffraction studies. Up to now, most XRD studies on lithium-ion battery materials have been done ex situ. Although these ex situ XRD studies have provided important information· about the structures of battery materials, they do face three major problems. First of all, the pre-selected charge (discharge) states may

  20. Computational Electrochemistry. Voltages of Lithium-Ion Battery Cathodes.

    PubMed

    Wang, Bo; Luo, Sijie; Truhlar, Donald G

    2016-03-01

    Theoretical studies on the electrode materials in lithium-ion batteries provide information on the structural changes during the charging and discharging processes. In the present study, we tested the M06-L and N12 exchange-correlation functionals on some well-studied lithium-containing materials. These functionals, which have already shown good performance for a variety of databases, outperform the widely used PBE functional for reproducing the experimental structures and averaged intercalation potentials. It is especially noteworthy that the M06-L functional gives voltages as accurate as those provided by the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional, but with less computational cost. PMID:26046813

  1. [Newly developed monitor for IVR: liquid crystal display (LCD) replaced with cathode ray tube (CRT)].

    PubMed

    Ichida, Takao; Hosogai, Minoru; Yokoyama, Kouji; Ogawa, Takayoshi; Okusako, Kenji; Shougaki, Masachika; Masai, Hironao; Yamada, Eiji; Okuyama, Kazuo; Hatagawa, Masakatsu

    2004-09-01

    For physicians who monitor images during interventional radiology (VR), we have built and been using a system that employs a liquid crystal display (LCD) instead of the conventional cathode ray tube (CRT). The system incorporates a ceiling-suspension-type monitor (three-display monitor) with an LCD on each of the three displays for the head and abdominal regions and another ceiling-suspension-type monitor (5-display monitor) with an LCD on each display for the cardiac region. As these monitors are made to be thin and light in weight, they can be placed in a high position in the room, thereby saving space and allowing for more effective use of space in the X-ray room. The system has also improved the efficiency of operators in the IVR room. The three-display folding mechanism allows the displays to be viewed from multiple directions, thereby improving the environment so that the performance of IVR can be observed.

  2. Interlaced X-ray diffraction computed tomography

    PubMed Central

    Vamvakeros, Antonios; Jacques, Simon D. M.; Di Michiel, Marco; Senecal, Pierre; Middelkoop, Vesna; Cernik, Robert J.; Beale, Andrew M.

    2016-01-01

    An X-ray diffraction computed tomography data-collection strategy that allows, post experiment, a choice between temporal and spatial resolution is reported. This strategy enables time-resolved studies on comparatively short timescales, or alternatively allows for improved spatial resolution if the system under study, or components within it, appear to be unchanging. The application of the method for studying an Mn–Na–W/SiO2 fixed-bed reactor in situ is demonstrated. Additionally, the opportunities to improve the data-collection strategy further, enabling post-collection tuning between statistical, temporal and spatial resolutions, are discussed. In principle, the interlaced scanning approach can also be applied to other pencil-beam tomographic techniques, like X-ray fluorescence computed tomography, X-ray absorption fine structure computed tomography, pair distribution function computed tomography and tomographic scanning transmission X-ray microscopy. PMID:27047305

  3. Computer program for optical systems ray tracing

    NASA Technical Reports Server (NTRS)

    Ferguson, T. J.; Konn, H.

    1967-01-01

    Program traces rays of light through optical systems consisting of up to 65 different optical surfaces and computes the aberrations. For design purposes, paraxial tracings with astigmation and third order tracings are provided.

  4. Novel Low-Cost, Low-Power Miniature Thermionic Cathode Developed for Microwave/Millimeter Wave Tube and Cathode Ray Tube Applications

    NASA Technical Reports Server (NTRS)

    Wintucky, Edwin G.

    1999-01-01

    A low cost, small size and mass, low heater power, durable high-performance barium dispenser thermionic cathode has been developed that offers significant advancements in the design, manufacture, and performance of the electron sources used in vacuum electronic devices--such as microwave (and millimeter wave) traveling-wave tubes (TWT's)--and in display devices such as high-brightness, high-resolution cathode ray tubes (CRT's). The lower cathode heater power and the reduced size and mass of the new cathode are expected to be especially beneficial in TWT's for deep space communications, where future missions are requiring smaller spacecraft, higher data transfer rates (higher frequencies and radiofrequency output power), and greater electrical efficiency. Also expected to benefit are TWT's for commercial and government communication satellites, for both low and geosynchronous Earth orbit, with additional benefits offered by lower cost and potentially higher cathode current loading. A particularly important TWT application is in the microwave power module (MPM), which is a hybrid microwave (or millimeter wave) amplifier consisting of a low-noise solid state driver, a vacuum power booster (small TWT), and an electronic power conditioner integrated into a single compact package. The attributes of compactness and potentially high electrical efficiency make the MPM very attractive for many commercial and government (civilian and defense) applications in communication and radar systems. The MPM is already finding application in defense electronic systems and is under development by NASA for deep space communications. However, for the MPM to become competitive and commercially successful, a major reduction in cost must be achieved.

  5. COMPUTATIONAL MODELING OF CATHODIC LIMITATIONS ON LOCALIZED CORROSION OF WETTED SS 316L, AT ROOM TEMPERATURE

    SciTech Connect

    F. Cui; F.J. Presuel-Moreno; R.G. Kelly

    2005-10-13

    The ability of a SS316L surface wetted with a thin electrolyte layer to serve as an effective cathode for an active localized corrosion site was studied computationally. The dependence of the total net cathodic current, I{sub net}, supplied at the repassivation potential E{sub rp} (of the anodic crevice) on relevant physical parameters including water layer thickness (WL), chloride concentration ([Cl{sup -}]) and length of cathode (Lc) were investigated using a three-level, full factorial design. The effects of kinetic parameters including the exchange current density (i{sub o,c}) and Tafel slope ({beta}{sub c}) of oxygen reduction, the anodic passive current density (i{sub p}) (on the cathodic surface), and E{sub rp} were studied as well using three-level full factorial designs of [Cl{sup -}] and Lc with a fixed WL of 25 {micro}m. The study found that all the three parameters WL, [Cl{sup -}] and Lc as well as the interactions of Lc x WL and Lc x [Cl{sup -}] had significant impact on I{sub net}. A five-factor regression equation was obtained which fits the computation results reasonably well, but demonstrated that interactions are more complicated than can be explained with a simple linear model. Significant effects on I{sub net} were found upon varying either i{sub o,c}, {beta}{sub c}, or E{sub rp}, whereas i{sub p} in the studied range was found to have little impact. It was observed that I{sub net} asymptotically approached maximum values (I{sub max}) when Lc increased to critical minimum values. I{sub max} can be used to determine the stability of coupled localized corrosion and the critical Lc provides important information for experimental design and corrosion protection.

  6. Compact monochromatic flash x-ray generator utilizing a disk-cathode molybdenum tube.

    PubMed

    Sato, Eiichi; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Ichimaru, Toshio; Sato, Shigehiro; Takayama, Kazuyoshi; Ido, Hideaki

    2005-01-01

    The high-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -50 to -70 kV by a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing gap switches in the surge generator with a trigger device. The x-ray tube is a demountable diode, and the turbo molecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean molybdenum Kalpha lines are produced using a 20 microm-thick zirconium filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. At a charging voltage of -70 kV, the instantaneous tube voltage and current were 120 kV and 1.0 kA, respectively. The x-ray pulse widths were approximately 70 ns, and the generator produced instantaneous number of Kalpha photons was approximately 3 x 10(7) photons/cm2 per pulse at 0.5 m from the source of 3.0 mm in diameter.

  7. Compact monochromatic flash x-ray generator utilizing a disk-cathode molybdenum tube

    SciTech Connect

    Sato, Eiichi; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Ichimaru, Toshio; Sato, Shigehiro; Takayama, Kazuyoshi; Ido, Hideaki

    2005-01-01

    The high-voltage condensers in a polarity-inversion two-stage Marx surge generator are charged from -50 to -70 kV by a power supply, and the electric charges in the condensers are discharged to an x-ray tube after closing gap switches in the surge generator with a trigger device. The x-ray tube is a demountable diode, and the turbo molecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean molybdenum K{alpha} lines are produced using a 20 {mu}m-thick zirconium filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. At a charging voltage of -70 kV, the instantaneous tube voltage and current were 120 kV and 1.0 kA, respectively. The x-ray pulse widths were approximately 70 ns, and the generator produced instantaneous number of K{alpha} photons was approximately 3x10{sup 7} photons/cm{sup 2} per pulse at 0.5 m from the source of 3.0 mm in diameter.

  8. X-ray Computed Tomography.

    ERIC Educational Resources Information Center

    Michael, Greg

    2001-01-01

    Describes computed tomography (CT), a medical imaging technique that produces images of transaxial planes through the human body. A CT image is reconstructed mathematically from a large number of one-dimensional projections of a plane. The technique is used in radiological examinations and radiotherapy treatment planning. (Author/MM)

  9. Deciphering the thermal behavior of lithium rich cathode material by in situ X-ray diffraction technique

    NASA Astrophysics Data System (ADS)

    Muhammad, Shoaib; Lee, Sangwoo; Kim, Hyunchul; Yoon, Jeongbae; Jang, Donghyuk; Yoon, Jaegu; Park, Jin-Hwan; Yoon, Won-Sub

    2015-07-01

    Thermal stability is one of the critical requirements for commercial operation of high energy lithium-ion batteries. In this study, we use in situ X-ray diffraction technique to elucidate the thermal degradation mechanism of 0.5Li2MnO3-0.5LiNi0.33Co0.33Mn0.33O2 lithium rich cathode material in the absence and presence of electrolyte to simulate the real life battery conditions and compare its thermal behavior with the commercial LiNi0.33Co0.33Mn0.33O2 cathode material. We show that the thermal induced phase transformations in delithiated lithium rich cathode material are much more intense compared to similar single phase layered cathode material in the presence of electrolyte. The structural changes in both cathode materials with the temperature rise follow different trends in the absence and presence of electrolyte between 25 and 600 °C. Phase transitions are comparatively simple in the absence of electrolyte, the fully charged lithium rich cathode material demonstrates better thermal stability by maintaining its phase till 379 °C, and afterwards spinel structure is formed. In the presence of electrolyte, however, the spinel structure appears at 207 °C, subsequently it transforms to rock salt type cubic phase at 425 °C with additional metallic, metal fluoride, and metal carbonate phases.

  10. Innovated application of mechanical activation to separate lead from scrap cathode ray tube funnel glass.

    PubMed

    Yuan, Wenyi; Li, Jinhui; Zhang, Qiwu; Saito, Fumio

    2012-04-01

    The disposal of scrap cathode ray tube (CRT) funnel glass has become a global environmental problem due to the rapid shrinkage of new CRT monitor demand, which greatly reduces the reuse for remanufacturing. To detoxificate CRT funnel glass by lead recovery with traditional metallurgical methods, mechanical activation by ball milling was introduced to pretreat the funnel glass. As a result, substantial physicochemical changes have been observed after mechanical activation including chemical breakage and defects formation in glass inner structure. These changes contribute to the easy dissolution of the activated sample in solution. High yield of 92.5% of lead from activated CRT funnel glass by diluted nitric acid leaching and successful formation of lead sulfide by sulfur sulfidization in water have also been achieved. All the results indicate that the application of mechanical activation on recovering lead from CRT funnel glass is efficient and promising, which is also probably appropriate to detoxificate any other kind of leaded glass.

  11. Evaluating the economic viability of a material recovery system: the case of cathode ray tube glass.

    PubMed

    Gregory, Jeremy R; Nadeau, Marie-Claude; Kirchain, Randolph E

    2009-12-15

    This paper presents an analysis of the material recovery system for leaded glass from cathode ray tubes (CRTs) using a dynamic material flow analysis. In particular, the global mass flow of primary and secondary CRT glass and the theoretical capacities for using secondary CRT glass to make new CRT glass are analyzed. The global mass flow analysis indicates that the amount of new glass required is decreasing, but is much greater than the amount of secondary glass collected, which is increasing. The comparison of the ratio of secondary glass collected to the amount of new glass required from the mass flow analysis indicates that the material recovery system is sustainable for the foreseeable future. However, a prediction of the time at which the market for secondary glass will collapse due to excess capacity is not possible at the moment due to several sources of uncertainty.

  12. Study on the mechanical and environmental properties of concrete containing cathode ray tube glass aggregate.

    PubMed

    Romero, Diego; James, Jacqueline; Mora, Rodrigo; Hays, Carol D

    2013-07-01

    Cathode ray tube (CRT) glass is considered a hazardous material due to its lead toxicity. In addition, current disposal practices are being phased out due to their adverse environmental impacts. In this project, CRT glass was used as a fine aggregate replacement in concrete. Life-cycle material characterization was conducted by evaluating the durability and strength of the CRT-Concrete. Leaching tests were also conducted to investigate whether the material meets drinking water limits for Pb. Test results show that the plastic state of the CRT-Concrete was affected by the angularity of the glass particles. Moreover, the compressive strength of CRT-Concrete met and exceeded that of the control specimen. However, CRT-Concrete was susceptible to expansive alkali-silica reactions when more than 10% CRT replacement was used. Environmental leaching results show that lead concentrations from CRT-Concrete are below the drinking water limits depending on the CRT volume replacement and if biopolymers are used.

  13. Detoxification of cathode ray tube glass by self-propagating process.

    PubMed

    Chen, Mengjun; Zhang, Fu-Shen; Zhu, Jianxin

    2009-06-15

    A novel process for the treatment of hazardous waste Cathode Ray Tube (CRT) glass, based on self-propagating reaction, was proposed. In the process, various types of CRT glass powders were blended with suitable amount of ferric oxide and magnesium, and the mixtures could generate self-propagating reaction once locally ignited by a thermal source. Generally, the self-propagating reaction could be well maintained when the CRT glass content in the mixture was no more than 60 wt.%, and the combustion wave velocity and maximum combustion temperature decreased along with the increase in glass amount. XPS experiments showed that heavy elements in the final products became more stable and were solidified during the process. Leaching tests demonstrated that heavy metals in the final products fulfilled the environmental regulations of USEPA. It is supposed that the detoxified products have the potential of being used as construction materials.

  14. Evaluation of Cathode-Ray Tube protection for the electronic tabular display subsystem (ETABS) engineering model

    NASA Astrophysics Data System (ADS)

    Wilson, A. R.

    1981-09-01

    This report describes the safety evaluation of the 25-inch (diagonal) rectangular cathode-ray tube (CRT) that is used in the engineering model of the Electronic Tabular Display Subsystem (ETABS). An evaluation of ETABS will be performed at the Federal Aviation Administration (FAA) Technical Center for possible application in FAA Air Route Traffic Control Centers (ARTCC). The safety evaluation included standard industry pressure testing and special implosion testing on 12 CRT samples. Eleven of the twelve CRT samples satisfactorily met the safety requirements for both the pressure and implosion testing. One CRT cracked when subjected to 45 pounds per square inch (psi) of air pressure; however, the CRT did not implode. The 25-inch rectangular CRT will therefore provide a high degree of safety for use in each of the two tabular displays of the ETABS engineering model.

  15. In Situ X-ray Diffraction Studies of Cathode Materials in Lithium Batteries

    SciTech Connect

    Yang, X. Q.; Sun, X.; McBreen, J.; Mukerjee, S.; Gao, Yuan; Yakovleva, M. V.; Xing, X. K.; Daroux, M. L.

    1998-11-01

    There is an increasing interest in lithiated transition metal oxides because of their use as cathodes in lithium batteries. LiCoO{sub 2}, LiNiO{sub 2} and LiMn{sub 2}O{sub 4} are the three most widely used and studied materials, At present, although it is relative expensive and toxic, LiCoO{sub 2} is the material of choice in commercial lithium ion batteries because of its ease of manufacture, better thermal stability and cycle life. However, the potential use of lithium ion batteries with larger capacity for power tools and electric vehicles in the future will demand new cathode materials with higher energy density, lower cost and better thermal stability. LiNiO{sub 2} is isostructural with LiCoO{sub 2}. It offers lower cost and high energy density than LiCoO{sub 2}. However, it has much poorer thermal stability than LiCoO{sub 2}, in the charged (delithiated) state. Co, Al, and other elements have been used to partially replace Ni in LiNiO{sub 2} system in order to increase the thermal stability. LiMn{sub 2}O{sub 4} has the highest thermal stability and lowest cost and toxicity. However, the low energy density and poor cycle life at elevated temperature are the major obstacles for this material. In order to develop safer, cheaper, and better performance cathode materials, the in-depth understanding of the relationships between the thermal stability and structure, performance and structure are very important. The performance here includes energy density and cycle life of the cathode materials. X-ray diffraction (XRD) is one of the most powerful tools to study these relationships. The pioneer ex situ XRD work on cathode materials for lithium batteries was done by Ohzuku. His XRD studies on LiMn{sub 2}O{sub 4}, LiCoO{sub 2}, LiNiO{sub 2}, LiNi{sub 0.5}Co{sub 0.5}O{sub 2}, and LiAl{sub x}Ni{sub 1-x}O{sub 2} cathodes at different states of charge have provided important guidelines for the development of these new materials. However, the kinetic nature of the battery

  16. 40 CFR 261.39 - Conditional Exclusion for Used, Broken Cathode Ray Tubes (CRTs) and Processed CRT Glass...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... complete until any such claim is resolved in accordance with 40 CFR 260.2. (v) The export of CRTs is... CFR part 266, subpart C instead of the requirements of this section. ... Cathode Ray Tubes (CRTs) and Processed CRT Glass Undergoing Recycling. 261.39 Section 261.39 Protection...

  17. 40 CFR 261.39 - Conditional Exclusion for Used, Broken Cathode Ray Tubes (CRTs) and Processed CRT Glass...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... complete until any such claim is resolved in accordance with 40 CFR 260.2. (v) The export of CRTs is... CFR part 266, subpart C instead of the requirements of this section. ... Cathode Ray Tubes (CRTs) and Processed CRT Glass Undergoing Recycling. 261.39 Section 261.39 Protection...

  18. 40 CFR 261.39 - Conditional Exclusion for Used, Broken Cathode Ray Tubes (CRTs) and Processed CRT Glass...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... complete until any such claim is resolved in accordance with 40 CFR 260.2. (v) The export of CRTs is... CFR part 266, subpart C instead of the requirements of this section. ... Cathode Ray Tubes (CRTs) and Processed CRT Glass Undergoing Recycling. 261.39 Section 261.39 Protection...

  19. 40 CFR 261.39 - Conditional Exclusion for Used, Broken Cathode Ray Tubes (CRTs) and Processed CRT Glass...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... complete until any such claim is resolved in accordance with 40 CFR 260.2. (v) The export of CRTs is... CFR part 266, subpart C instead of the requirements of this section. ... Cathode Ray Tubes (CRTs) and Processed CRT Glass Undergoing Recycling. 261.39 Section 261.39 Protection...

  20. 40 CFR 261.39 - Conditional Exclusion for Used, Broken Cathode Ray Tubes (CRTs) and Processed CRT Glass...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... complete until any such claim is resolved in accordance with 40 CFR 260.2. (v) The export of CRTs is... CFR part 266, subpart C instead of the requirements of this section. § 261.39, Nt. Effective Date Note... Cathode Ray Tubes (CRTs) and Processed CRT Glass Undergoing Recycling. 261.39 Section 261.39 Protection...

  1. 40 CFR 261.40 - Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling. 261.40 Section 261.40 Protection of Environment...) Exported for Recycling. Used, intact CRTs exported for recycling are not solid wastes if they meet...

  2. 40 CFR 261.40 - Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling. 261.40 Section 261.40 Protection of Environment...) Exported for Recycling. Used, intact CRTs exported for recycling are not solid wastes if they meet...

  3. 40 CFR 261.40 - Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling. 261.40 Section 261.40 Protection of Environment...) Exported for Recycling. Used, intact CRTs exported for recycling are not solid wastes if they meet...

  4. 40 CFR 261.40 - Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 26 2014-07-01 2014-07-01 false Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling. 261.40 Section 261.40 Protection of Environment...) Exported for Recycling. Used, intact CRTs exported for recycling are not solid wastes if they meet...

  5. 40 CFR 261.40 - Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Conditional Exclusion for Used, Intact Cathode Ray Tubes (CRTs) Exported for Recycling. 261.40 Section 261.40 Protection of Environment...) Exported for Recycling. Used, intact CRTs exported for recycling are not solid wastes if they meet...

  6. High Power Experiment of X-Band Thermionic Cathode RF Gun for Compton Scattering X-ray Source

    SciTech Connect

    Sakamoto, Fumito; Uesaka, Mitsuru; Dobashi, Katsuhiro; Yamamoto, Tomohiko; Meng, De; Urakawa, Junji; Higo, Toshiyasu; Akemoto, Mitsuo; Matsuo, Kenichi; Sakae, Hisaharu; Yamamoto, Masashi

    2006-11-27

    We are currently developing a compact monochromatic X-ray source based on laser-electron collision. To realize remarkably compact-, high-intensity- and highly-stable-system, we adopt an X-band multi-bunch liner accelerator (linac) and reliable Q-switch laser. The X-ray yields by the multi-bunch electron beam and Q-switch Nd: YAG laser of 1.4 J/10 ns (FWHM) (532 nm, second harmonic) is 107 photons/RF-pulse (108 photons/sec for 10 Hz operation). The injector of the system consists of a 3.5-cell X-band thermionic cathode RF gun and an alpha magnet. So far we have achieved beam generation from the X-band thermionic cathode RF gun. The peak beam energy is 2 MeV. This experimental high energy ({approx}2 MeV) beam generation from the X-band thermionic cathode RF gun is the first in the world. In this paper, we describe the system of the Compton scattering X-ray source based on the X-band linac, experimental results of X-band thermionic cathode RF gun and the details of the experimental setup for Compton scattering X-ray generation that are under construction.

  7. X-ray Absorption Measurements on Nickel Cathode of Sodium-beta Alumina batteries: Fe-Ni-CI Chemical Associations

    SciTech Connect

    Bowden, Mark E.; Alvine, Kyle J.; Fulton, John L.; Lemmon, John P.; Lu, Xiaochuan; Webb-Robertson, Bobbie-Jo M.; Heald, Steve M.; Balasubramanian, Mahalingam; Mortensen, Devon R.; Seidler, Gerald T.; Hess, Nancy J.

    2014-02-01

    Sections of Na-Al-NiCl2 cathodes from sodium-beta alumina ZEBRA batteries have been characterized with X-ray fluorescence mapping, and XANES measurements to probe the microstructure, elemental correlation, and chemical speciation after voltage cycling. Cycling was performed under identical load conditions at either 240 or 280 °C operating temperature and subsequently quenched in either the charged or discharged state. X-ray fluorescence mapping and XANES measurements were made adjacent to the current collector and β"-Al2O3 solid electrolyte interfaces to detect possible gradients in chemical properties across the cathode. An FeS additive, introduced during battery synthesis, was found to be present as either Fe metal or an Fe(II) chloride in all cathode samples. X-ray fluorescence mapping reveals an operating temperature and charge-state dependent spatial correlation between Fe, Ni, and Cl concentration. XANES measurements indicate that both Ni and Fe are chemically reactive and shift between metallic and chloride phases in the charged and discharged states, respectively. However the percentage of chemically active Ni and Fe is significantly less in the cell operated at lower temperature. Additionally, the cathode appeared chemically homogeneous at the scale of our X-ray measurements.

  8. The Fine-Beam Cathode-Ray Tube and the Observant and Enquiring Student--Part 2.

    ERIC Educational Resources Information Center

    Webb, John le P.

    1984-01-01

    Discusses use of the fine-beam cathode-ray tube to investigate strength and direction of the earth's magnetic field, simulating discussion between student and teacher as the equipment is set up and the experiment done. Provides diagrams and illustrative photographs to aid in equipment set-up and measurement. (JM)

  9. 40 CFR 261.41 - Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse. 261.41 Section 261.41 Protection of... Tubes (CRTs) Exported for Reuse. (a) Persons who export used, intact CRTs for reuse must send a...

  10. 40 CFR 261.41 - Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse. 261.41 Section 261.41 Protection of... Tubes (CRTs) Exported for Reuse. (a) Persons who export used, intact CRTs for reuse must send a...

  11. 40 CFR 261.41 - Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse. 261.41 Section 261.41 Protection of... Tubes (CRTs) Exported for Reuse. (a) Persons who export used, intact CRTs for reuse must send a...

  12. 40 CFR 261.41 - Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Notification and Recordkeeping for Used, Intact Cathode Ray Tubes (CRTs) Exported for Reuse. 261.41 Section 261.41 Protection of... Tubes (CRTs) Exported for Reuse. (a) Persons who export used, intact CRTs for reuse must send a...

  13. Recovery of yttrium from cathode ray tubes and lamps’ fluorescent powders: experimental results and economic simulation

    SciTech Connect

    Innocenzi, V. De Michelis, I.; Ferella, F.; Vegliò, F.

    2013-11-15

    Highlights: • Fluorescent powder of lamps. • Fluorescent powder of cathode ray rubes. • Recovery of yttrium from fluorescent powders. • Economic simulation for the processes to recover yttrium from WEEE. - Abstract: In this paper, yttrium recovery from fluorescent powder of lamps and cathode ray tubes (CRTs) is described. The process for treating these materials includes the following: (a) acid leaching, (b) purification of the leach liquors using sodium hydroxide and sodium sulfide, (c) precipitation of yttrium using oxalic acid, and (d) calcinations of oxalates for production of yttrium oxides. Experimental results have shown that process conditions necessary to purify the solutions and recover yttrium strongly depend on composition of the leach liquor, in other words, whether the powder comes from treatment of CRTs or lamp. In the optimal experimental conditions, the recoveries of yttrium oxide are about 95%, 55%, and 65% for CRT, lamps, and CRT/lamp mixture (called MIX) powders, respectively. The lower yields obtained during treatments of MIX and lamp powders are probably due to the co-precipitation of yttrium together with other metals contained in the lamps powder only. Yttrium loss can be reduced to minimum changing the experimental conditions with respect to the case of the CRT process. In any case, the purity of final products from CRT, lamps, and MIX is greater than 95%. Moreover, the possibility to treat simultaneously both CRT and lamp powders is very important and interesting from an industrial point of view since it could be possible to run a single plant treating fluorescent powder coming from two different electronic wastes.

  14. Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation.

    PubMed

    Innocenzi, Valentina; De Michelis, Ida; Ferella, Francesco; Beolchini, Francesca; Kopacek, Bernd; Vegliò, Francesco

    2013-11-01

    This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2(2) full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3M of sulphuric acid, 10% v/v of H2O2 concentrated solution at 30% v/v, 10% w/w pulp density, 70°C and 3h of reaction. Two series of precipitation tests for zinc are carried out: a 2(2) full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2-2.5% and 10-12%v/v of Na2S concentrated solution at 10%w/v. In these conditions the coprecipitation of yttrium is of 15-20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75-80%.

  15. Utilization of recycled cathode ray tubes glass in cement mortar for X-ray radiation-shielding applications.

    PubMed

    Ling, Tung-Chai; Poon, Chi-Sun; Lam, Wai-Shung; Chan, Tai-Po; Fung, Karl Ka-Lok

    2012-01-15

    Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximately 3.0 g/cm(3) can be potentially suitable to be used as fine aggregate for preparing cement mortars for X-ray radiation-shielding applications. In this work, the effects of using crushed glass derived from crushed CRT funnel glass (both acid washed and unwashed) and crushed ordinary beverage container glass at different replacement levels (0%, 25%, 50%, 75% and 100% by volume) of sand on the mechanical properties (strength and density) and radiation-shielding performance of the cement-sand mortars were studied. The results show that all the prepared mortars had compressive strength values greater than 30 MPa which are suitable for most building applications based on ASTM C 270. The density and shielding performance of the mortar prepared with ordinary crushed (lead-free) glass was similar to the control mortar. However, a significant enhancement of radiation-shielding was achieved when the CRT glasses were used due to the presence of lead in the glass. In addition, the radiation shielding contribution of CRT glasses was more pronounced when the mortar was subject to a higher level of X-ray energy.

  16. Utilization of recycled cathode ray tubes glass in cement mortar for X-ray radiation-shielding applications.

    PubMed

    Ling, Tung-Chai; Poon, Chi-Sun; Lam, Wai-Shung; Chan, Tai-Po; Fung, Karl Ka-Lok

    2012-01-15

    Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximately 3.0 g/cm(3) can be potentially suitable to be used as fine aggregate for preparing cement mortars for X-ray radiation-shielding applications. In this work, the effects of using crushed glass derived from crushed CRT funnel glass (both acid washed and unwashed) and crushed ordinary beverage container glass at different replacement levels (0%, 25%, 50%, 75% and 100% by volume) of sand on the mechanical properties (strength and density) and radiation-shielding performance of the cement-sand mortars were studied. The results show that all the prepared mortars had compressive strength values greater than 30 MPa which are suitable for most building applications based on ASTM C 270. The density and shielding performance of the mortar prepared with ordinary crushed (lead-free) glass was similar to the control mortar. However, a significant enhancement of radiation-shielding was achieved when the CRT glasses were used due to the presence of lead in the glass. In addition, the radiation shielding contribution of CRT glasses was more pronounced when the mortar was subject to a higher level of X-ray energy. PMID:22118845

  17. X-ray Diffraction Studies of the Structure and Thermochemistry of Alkaline-Earth Oxide-Coated Thermionic Cathodes

    NASA Technical Reports Server (NTRS)

    Karikari, E. K.; Bassey, E.; Wintucky, Edwin G.

    1998-01-01

    NASA LeRC has a broad, active cathode technology development program in which both experimental and theoretical studies are being employed to further development of thermionic cathodes for use as electron sources in vacuum devices for communications and other space applications. One important type of thermionic cathode under development is the alkaline-earth oxide-coated (BaO, SrO, CaO) cathode. Significant improvements in the emission characteristics of this cathode have been obtained through modification of the chemical composition and morphology of the oxide coating, with the best result thus far coming from the addition of In2O3 and Sc2O3. Whereas the In2O3 produces a finer, more uniform particle structure, the exact chemical state and role of the Sc2O3 in the emission enhancement is unknown. The purpose of this cooperative agreement is to combine the studies of the surface chemistry and electron emission at NASA LeRC of chemically modified oxide coatings with a study of the thermochemistry and crystal structure using X-ray diffraction equipment and expertise at Clark Atlanta University (CAU). The study at CAU is intended to provide the description and understanding of the structure and thermochemistry needed for further improvement and optimization of the modified coatings. A description of the experimental procedure, preliminary X-ray diffraction test results, together with the design of an ultrahigh vacuum chamber necessary for high temperature thermochemistry studies will be presented.

  18. Lead extraction from cathode ray tube funnel glass melted under different oxidizing conditions.

    PubMed

    Okada, Takashi

    2015-07-15

    Lead was extracted into hydrochloric acid from cathode ray tube funnel glass melted under reducing atmosphere, oxidizing atmosphere, or a sequential combination of both to mechanistically investigate effects of the melting atmosphere on lead extraction. Melting funnel glass in a reductive atmosphere led to the generation of metallic lead particles that were readily soluble in the acid, increasing the quantity of lead extracted into the acid. Meanwhile, the glass product obtained after melting funnel glass in an oxidative atmosphere exhibited higher corrosion resistance in the acid, and the quantity of lead extracted from the treated glass decreased. However, Na2CO3 addition to the glass during melting hindered the enhancement of corrosion resistance and the immobilization of lead in the acid. X-ray photoelectron spectroscopic analysis of the treated glass samples showed that the positions of the peak or the profiles of the spectra attributed to Pb 4f, Si 2p, and O 1s signals were modified by oxidative melting, an indication that oxidative melting results in structural changes in the SiO2 framework of the glass.

  19. Disk-cathode flash X-ray tube driven by a repetitive two-stage Marx pulser.

    PubMed

    Kimura, S; Sato, E; Sagae, M; Shikoda, A; Oizumi, T; Takahashi, K; Tamakawa, Y; Yanagisawa, T

    1993-07-01

    Fundamental studies of a repetitive flash X-ray generator using a disk-cathode radiation tube are described. The high-voltage pulser employed a modified two-stage surge-Marx circuit. The two condensers in the pulser were charged from 40 to 60 kV, and the electric charges were discharged to the X-ray tube repetitively to generate flash X-rays. The total capacity during the main discharge was 425 pF, and the maximum output voltage from the pulser was about 1.9 times the charged voltage. The flash X-ray tube was of the demountable-diode type and was composed of a rod-shaped anode tip made of tungsten, a disk cathode made of graphite and a tube body made of polymethylmethacrylate. The peak tube voltage was primarily determined by the anode-cathode (A-C) space, and the peak tube current was less than 0.5 kA. Thus the maximum photon energy could be easily controlled by varying the A-C space, and the tube current roughly increased according to increases in the charged voltage. The pulse width ranged from 40 to 100 ns, and the X-ray intensity was less than 1.1 microC kg-1 at 0.5 m per pulse. The repetition rate was less than 50 Hz, and the effective focal spot size was equivalent to the anode diameter.

  20. Use of limestone powder during incorporation of Pb-containing cathode ray tube waste in self-compacting concrete.

    PubMed

    Sua-iam, Gritsada; Makul, Natt

    2013-10-15

    For several decades, cathode ray tubes (CRTs) were the primary display component of televisions and computers. The CRT glass envelope contains sufficient levels of lead oxide (PbO) to be considered hazardous, and there is a need for effective methods of permanently encapsulating this material during waste disposal. We examined the effect of adding limestone powder (LS) on the fresh and cured properties of self-compacting concrete (SCC) mixtures containing waste CRT glass. The SCC mixtures were prepared using Type 1 Portland cement at a constant cement content of 600 kg/m(3) and a water-to-cement ratio (w/c) of 0.38. CRT glass waste cullet was blended with river sand in proportions of 20 or 40% by weight. To suppress potential viscosity effects limestone powder was added at levels of 5, 10, or 15% by weight. The slump flow time, slump flow diameter, V-funnel flow time, Marsh cone flow time, and setting time of the fresh concrete were tested, as well as the compressive strength and ultrasonic pulse velocity of the hardened concrete. Addition of limestone powder improved the fresh and hardened properties. Pb leaching levels from the cured concrete were within US EPA allowable limits. PMID:23892134

  1. Use of limestone powder during incorporation of Pb-containing cathode ray tube waste in self-compacting concrete.

    PubMed

    Sua-iam, Gritsada; Makul, Natt

    2013-10-15

    For several decades, cathode ray tubes (CRTs) were the primary display component of televisions and computers. The CRT glass envelope contains sufficient levels of lead oxide (PbO) to be considered hazardous, and there is a need for effective methods of permanently encapsulating this material during waste disposal. We examined the effect of adding limestone powder (LS) on the fresh and cured properties of self-compacting concrete (SCC) mixtures containing waste CRT glass. The SCC mixtures were prepared using Type 1 Portland cement at a constant cement content of 600 kg/m(3) and a water-to-cement ratio (w/c) of 0.38. CRT glass waste cullet was blended with river sand in proportions of 20 or 40% by weight. To suppress potential viscosity effects limestone powder was added at levels of 5, 10, or 15% by weight. The slump flow time, slump flow diameter, V-funnel flow time, Marsh cone flow time, and setting time of the fresh concrete were tested, as well as the compressive strength and ultrasonic pulse velocity of the hardened concrete. Addition of limestone powder improved the fresh and hardened properties. Pb leaching levels from the cured concrete were within US EPA allowable limits.

  2. Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation

    SciTech Connect

    Innocenzi, Valentina; De Michelis, Ida; Ferella, Francesco; Beolchini, Francesca; Kopacek, Bernd

    2013-11-15

    Highlights: • Treatment of fluorescent powder of CRT waste. • Factorial experimental designs to study acid leaching of fluorescent powder and the purification of leach liquors. • Recover of yttrium by precipitation using oxalic acid. • Suitable flowsheet to recover yttrium from fluorescent powder. - Abstract: This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2{sup 2} full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3 M of sulphuric acid, 10% v/v of H{sub 2}O{sub 2} concentrated solution at 30% v/v, 10% w/w pulp density, 70 °C and 3 h of reaction. Two series of precipitation tests for zinc are carried out: a 2{sup 2} full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2–2.5% and 10–12% v/v of Na{sub 2}S concentrated solution at 10% w/v. In these conditions the coprecipitation of yttrium is of 15–20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75–80%.

  3. Recovering lead from cathode ray tube funnel glass by mechano-chemical extraction in alkaline solution.

    PubMed

    Zhang, Chenglong; Wang, Jingwei; Bai, Jianfeng; Guan, Jie; Wu, Wenjie; Guo, Cuixiang

    2013-07-01

    This study evaluates the efficiency of lead (Pb) extraction from cathode ray tube (CRT) funnel glass in strongly alkaline solution using mechanical activation in a ball mill as the chemical breakage and defects formed in the inner structures will contribute to the easy dissolution of the activated Pb glass. The combination of mechanical activation and a chemical leaching process in a single operation (mechano-chemical leaching) is more effective than the mechanical activation and subsequent chemical leaching. More than 97% of Pb in the CRT funnel glass can be extracted with a stirring ball mill leaching process in 5 M sodium hydroxide at 70°C. The diameter of the stainless steel balls as the activation medium is 5 mm; the mass ratio of ball to raw materials is 25:1. Pb powder with a purity of 97% can be obtained by electrowinning from the leaching solution. The Pb-depleted solution can be recycled into the leaching step. After Pb is removed, the solid leaching residues can be used for preparation of foam glass. Thus, a novel hydrometallurgical process for recovering Pb from CRT funnel glass in alkaline solution is proposed. PMID:23592759

  4. Recovery of yttrium from cathode ray tubes and lamps' fluorescent powders: experimental results and economic simulation.

    PubMed

    Innocenzi, V; De Michelis, I; Ferella, F; Vegliò, F

    2013-11-01

    In this paper, yttrium recovery from fluorescent powder of lamps and cathode ray tubes (CRTs) is described. The process for treating these materials includes the following: (a) acid leaching, (b) purification of the leach liquors using sodium hydroxide and sodium sulfide, (c) precipitation of yttrium using oxalic acid, and (d) calcinations of oxalates for production of yttrium oxides. Experimental results have shown that process conditions necessary to purify the solutions and recover yttrium strongly depend on composition of the leach liquor, in other words, whether the powder comes from treatment of CRTs or lamp. In the optimal experimental conditions, the recoveries of yttrium oxide are about 95%, 55%, and 65% for CRT, lamps, and CRT/lamp mixture (called MIX) powders, respectively. The lower yields obtained during treatments of MIX and lamp powders are probably due to the co-precipitation of yttrium together with other metals contained in the lamps powder only. Yttrium loss can be reduced to minimum changing the experimental conditions with respect to the case of the CRT process. In any case, the purity of final products from CRT, lamps, and MIX is greater than 95%. Moreover, the possibility to treat simultaneously both CRT and lamp powders is very important and interesting from an industrial point of view since it could be possible to run a single plant treating fluorescent powder coming from two different electronic wastes.

  5. Study on the mechanical and environmental properties of concrete containing cathode ray tube glass aggregate.

    PubMed

    Romero, Diego; James, Jacqueline; Mora, Rodrigo; Hays, Carol D

    2013-07-01

    Cathode ray tube (CRT) glass is considered a hazardous material due to its lead toxicity. In addition, current disposal practices are being phased out due to their adverse environmental impacts. In this project, CRT glass was used as a fine aggregate replacement in concrete. Life-cycle material characterization was conducted by evaluating the durability and strength of the CRT-Concrete. Leaching tests were also conducted to investigate whether the material meets drinking water limits for Pb. Test results show that the plastic state of the CRT-Concrete was affected by the angularity of the glass particles. Moreover, the compressive strength of CRT-Concrete met and exceeded that of the control specimen. However, CRT-Concrete was susceptible to expansive alkali-silica reactions when more than 10% CRT replacement was used. Environmental leaching results show that lead concentrations from CRT-Concrete are below the drinking water limits depending on the CRT volume replacement and if biopolymers are used. PMID:23628215

  6. Visual Evoked Potential Using Head-Mounted Display Versus Cathode Ray Tube: A Pilot Study

    PubMed Central

    Choi, Hyo Seon; Im, Sang Hee; Kim, Yong Kyun

    2016-01-01

    Objective To present a new stimulation method based on the use of a head-mounted display (HMD) during pattern reversal visual evoked potential (PR-VEP) testing and to compare variables of HMD to those of conventional cathode ray tube (CRT). Methods Twenty-three normal subjects without visual problems were recruited. PR-VEPs were generated using CRT or HMD stimuli. VEP outcome measures included latencies (N75, P100, and N145) and peak-to-peak amplitudes (N75–P100 and P100–N145). Subjective discomfort associated with HMD was determined using a self-administered questionnaire. Results PR-VEPs generated by HMD stimuli showed typical triphasic waveforms, the components of which were found to be correlated with those obtained using conventional CRT stimuli. Self-administered discomfort questionnaires revealed that HMD was more comfortable in some aspects. It allowed subjects to concentrate better than CRT. Conclusion The described HMD stimulation can be used as an alternative to the standard CRT stimulation for PR-VEPs. PR-VEP testing using HMD has potential applications in clinical practice and visual system research because HMD can be used on a wider range of subjects compared to CRT. PMID:27152285

  7. Water-soluble lead in cathode ray tube funnel glass melted in a reductive atmosphere.

    PubMed

    Okada, Takashi

    2016-10-01

    In the reduction-melting process, lead can be recovered from cathode ray tube funnel glass (PbO=25wt%); however, resulting glass residues still contain approximately 1-2wt% of unrecovered lead. For environmental protection in the residue disposal or recycling, it is important to evaluate the quantities of water-soluble species among the unrecovered lead. This study examined water-soluble lead species generated in the reduction-melting process of the funnel glass and factors determining their generation. In the reduction-melting, metallic lead was generated by reducing lead oxides in the glass, and a part of the metallic lead remained in the glass residue. Such unrecovered metallic lead can dissolve in water depending on its pH level and was regarded as water-soluble lead. When 10g Na2CO3 was added to 20g funnel glass during reduction-melting, the resulting glass contained high concentrations of sodium. In a water leaching of the glass, the obtained leachate was alkalized by the sodium-rich glass (pH=12.7-13.0). The unrecovered metallic lead in the glass was extracted in the alkalized leachate. The quantity of the unrecovered metallic lead (water-soluble lead) in the glass decreased when the melting time, melting temperature, and carbon dosage were controlled during reduction-melting. PMID:27209518

  8. Effective utilization of waste cathode ray tube glass--crystalline silicotitanate synthesis.

    PubMed

    Chen, Mengjun; Zhang, Fu-Shen; Zhu, Jianxin

    2010-10-15

    A novel process for crystalline silicotitanate (CST) synthesis was developed using waste cathode ray tube (CRT) panel glass as silicon source. The key trait of the process was to extract most of the silicon out of the glass for CST preparation, but leave Ba and Sr in the residue which had the potential to be employed as raw material for metallic Ba and Sr metallurgy. In the synthesis process, waste CRT panel glass was firstly treated by supercritical water (SCW)-NaOH solution for Si extraction, then sol-gel and hydrothermal treatments were used for CST preparation. 80% of Si in the glass could be extracted into the solution, while Sr and Ba were enriched in the residue in the form of Sr(2)SiO(4) and Ba(2)Si(3)O(8), respectively. Sr and Ba contents in the residue were 2-3 times higher than those in the raw glass. SEM, XRD and TEM results indicated that CST was successfully synthesized. Ion exchanging experiments showed that the batch distribution coefficient of the synthesized CST to Cs(+) was up to 1.2x10(4) mL/g at pH 0.26.

  9. Recovering lead from cathode ray tube funnel glass by mechano-chemical extraction in alkaline solution.

    PubMed

    Zhang, Chenglong; Wang, Jingwei; Bai, Jianfeng; Guan, Jie; Wu, Wenjie; Guo, Cuixiang

    2013-07-01

    This study evaluates the efficiency of lead (Pb) extraction from cathode ray tube (CRT) funnel glass in strongly alkaline solution using mechanical activation in a ball mill as the chemical breakage and defects formed in the inner structures will contribute to the easy dissolution of the activated Pb glass. The combination of mechanical activation and a chemical leaching process in a single operation (mechano-chemical leaching) is more effective than the mechanical activation and subsequent chemical leaching. More than 97% of Pb in the CRT funnel glass can be extracted with a stirring ball mill leaching process in 5 M sodium hydroxide at 70°C. The diameter of the stainless steel balls as the activation medium is 5 mm; the mass ratio of ball to raw materials is 25:1. Pb powder with a purity of 97% can be obtained by electrowinning from the leaching solution. The Pb-depleted solution can be recycled into the leaching step. After Pb is removed, the solid leaching residues can be used for preparation of foam glass. Thus, a novel hydrometallurgical process for recovering Pb from CRT funnel glass in alkaline solution is proposed.

  10. Nano-lead particle synthesis from waste cathode ray-tube funnel glass.

    PubMed

    Xing, Mingfei; Zhang, Fu-Shen

    2011-10-30

    Waste cathode ray-tube (CRT) funnel glass is classified as hazardous waste since it contains high amount of lead. In the present study, a novel process for lead nanopowder synthesis from this type of glass was developed by combining vacuum carbon-thermal reduction and inert-gas consolidation procedures. The key trait of the process was to evaporate lead out of the glass to obtain harmless glass powder and synchronously produce lead nanoparticles. In the synthesis process, lead oxide in the funnel glass was firstly reduced to elemental lead, and evaporated rapidly in vacuum circumstance, then quenched and formed nano-size particles on the surface of the cooling device. Experimental results showed that temperature, pressure and argon gas flow rate were the major parameters controlling lead evaporation ratio and the morphology of lead nanoparticles. The maximum lead evaporation ratio was 96.8% and particles of 4-34 nm were successfully obtained by controlling the temperature, holding time, process pressure, argon gas flow rate at 1000°C, 2-4h, 500-2000 Pa, 50-200 ml/min, respectively. Toxicity characteristic leaching procedure (TCLP) results showed that lead leaching from the residue glass met the USEPA threshold. Accordingly, this study developed a practical and environmental-friendly process for detoxification and reclamation of waste lead-containing glass.

  11. Water-soluble lead in cathode ray tube funnel glass melted in a reductive atmosphere.

    PubMed

    Okada, Takashi

    2016-10-01

    In the reduction-melting process, lead can be recovered from cathode ray tube funnel glass (PbO=25wt%); however, resulting glass residues still contain approximately 1-2wt% of unrecovered lead. For environmental protection in the residue disposal or recycling, it is important to evaluate the quantities of water-soluble species among the unrecovered lead. This study examined water-soluble lead species generated in the reduction-melting process of the funnel glass and factors determining their generation. In the reduction-melting, metallic lead was generated by reducing lead oxides in the glass, and a part of the metallic lead remained in the glass residue. Such unrecovered metallic lead can dissolve in water depending on its pH level and was regarded as water-soluble lead. When 10g Na2CO3 was added to 20g funnel glass during reduction-melting, the resulting glass contained high concentrations of sodium. In a water leaching of the glass, the obtained leachate was alkalized by the sodium-rich glass (pH=12.7-13.0). The unrecovered metallic lead in the glass was extracted in the alkalized leachate. The quantity of the unrecovered metallic lead (water-soluble lead) in the glass decreased when the melting time, melting temperature, and carbon dosage were controlled during reduction-melting.

  12. Hard X-ray Fluorescence Measurements of Heteroepitaxial Solid Oxide Fuel Cell Cathode Materials

    SciTech Connect

    Davis, Jacob N.; Miara, Lincoln J.; Saraf, Laxmikant V.; Kaspar, Tiffany C.; Gopalan, Srikanth; Pal, Uday B.; Woicik, Joseph C.; Basu, Soumendra N.; Ludwig, Karl F.

    2012-12-01

    Commonly, SOFCs are operated at high temperatures (above 800°C). At these temperatures expensive housing is needed to contain an operating stack as well as coatings to contain the oxidation of the metallic interconnects. Lowering the temperature of an operating device would allow for more conventional materials to be used, thus lowering overall cost. Understanding the surface chemical states of cations in the surface of the SOFC cathode is vital to designing a system that will perform well at lower temperatures. The samples studied were grown by pulsed laser deposition (PLD) at the Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). 20% strontium doped lanthanum manganite (LSM-20) was grown on YSZ and NGO (neodymium gallate). The films on YSZ have a fiber texture. LSM-20 on NGO is heteroepitaxial. Lanthanum strontium cobalt ferrite (LSCF-6428) films were grown on LAO and YSZ with a GDC barrier layer. Total X-ray Reflection Fluorescence (TXRF) was used to depth profile the samples. In a typical experiment, the angle of the incident beam is varied though the critical angle. Below the critical angle, the x-ray decays as an evanescent wave and will only penetrate the top few nanometers. TXRF experiments done on LSM films have suggested strontium segregates to the surface and form strontium enriched nanoparticles (1). It should be pointed out that past studies have focused on 30% strontium A-site doping, but this project uses 20% strontium doped lanthanum manganite. XANES and EXAFS data were taken as a function of incoming angle to probe composition as a function of depth. XANES spectra can be difficult to analyze fully. For other materials density functional theory calculations compared to near edge measurements have been a good way to understand the 3d valence electrons (2).

  13. Characterization of Cr poisoning in a solid oxide fuel cell cathode using a high-energy x-ray microbeam.

    SciTech Connect

    Liu, D. J.; Almer, J.; Cruse, T.

    2010-01-01

    A key feature of planar solid oxide fuel cells (SOFCs) is the feasibility of using metallic interconnects made of high temperature ferritic stainless steels, which reduce system cost while providing excellent electric conductivity. Such interconnects, however, contain high levels of chromium, which has been found to be associated with SOFC cathode performance degradation at SOFC operating temperatures; a phenomenon known as Cr poisoning. Here, we demonstrate an accurate measurement of the phase and concentration distributions of Cr species in a degraded SOFC, as well as related properties including deviatoric strain, integrated porosity, and lattice parameter variation, using high energy microbeam X-ray diffraction and radiography. We unambiguously identify (MnCr){sub 3}O{sub 4} and Cr{sub 2}O{sub 3} as the two main contaminant phases and find that their concentrations correlate strongly with the cathode layer composition. Cr{sub 2}O{sub 3} deposition within the active cathode region reduces porosity and produces compressive residual strains, which hinders the reactant gas percolation and can cause structural breakdown of the SOFC cathode. The information obtained through this study can be used to better understand the Cr-poisoning mechanism and improve SOFC design.

  14. Determination of Optimal Parameters for Dual-Layer Cathode of Polymer Electrolyte Fuel Cell Using Computational Intelligence-Aided Design

    PubMed Central

    Chen, Yi; Huang, Weina; Peng, Bei

    2014-01-01

    Because of the demands for sustainable and renewable energy, fuel cells have become increasingly popular, particularly the polymer electrolyte fuel cell (PEFC). Among the various components, the cathode plays a key role in the operation of a PEFC. In this study, a quantitative dual-layer cathode model was proposed for determining the optimal parameters that minimize the over-potential difference and improve the efficiency using a newly developed bat swarm algorithm with a variable population embedded in the computational intelligence-aided design. The simulation results were in agreement with previously reported results, suggesting that the proposed technique has potential applications for automating and optimizing the design of PEFCs. PMID:25490761

  15. 81.114- University Reactor Infrastructure and Education Support / Prompt Gamma-ray Activation Analysis of Lithioum Ion Battery Cathodes

    SciTech Connect

    Manthiram, Arumugam; Landsberger, S.

    2006-11-11

    This project focuses on the use of the Prompt Gamma-ray Activation Analysis (PGAA) technique available at the Nuclear Engineering Teaching Laboratory of the University of Texas at Austin to precisely determine the hydrogen (proton) contents in layered oxide cathode samples obtained by chemical lithium extraction in order to obtain a better understanding of the factors limiting the practical capacities and overall performance of lithium ion battery cathodes. The project takes careful precautionary experimental measures to avoid proton contamination both from solvents used in chemical delithiation and from ambient moisture. The results obtained from PGAA are complemented by the data obtained from other techniques such as thermogravimetric analysis, redox titration, atomic absorption spectroscopy, X-ray diffraction, and mass spectroscopic analysis of the evolved gas on heating. The research results broaden our understanding of the structure-property-performance relationships of lithium ion battery cathodes and could aid the design and development of new better performing lithium ion batteries for consumer (portable and electric vehicles), military, and space applications.

  16. Removal of lead from cathode ray tube funnel glass by combined thermal treatment and leaching processes.

    PubMed

    Okada, Takashi; Nishimura, Fumihiro; Yonezawa, Susumu

    2015-11-01

    The reduction melting process is useful to recover toxic lead from cathode ray tube funnel glass; however, this process generates SiO2-containing residues that are disposed in landfill sites. To reduce the volume of landfill waste, it is desirable to recycle the SiO2-containing residues. In this study, SiO2 powder was recovered from the residue generated by reduction melting. The funnel glass was treated by a process combining reduction melting at 1000°C and annealing at 700°C to recover a large quantity of lead from the glass. The oxide phase generated by the thermal treatment was subjected to water leaching and acid leaching with 1M hydrochloric acid to wash out unwanted non-SiO2 elements for SiO2 purification. In the water washing, the oxide phase was microparticulated, and porous structures formed on the oxide surfaces. This increased the surface area of the oxide phase, and the unwanted elements were effectively washed out during the subsequent acid leaching. By controlling the acid leaching time and the amount of added acid, porous and amorphous SiO2 (purity >95 wt%) was recovered. In the obtained SiO2-concentrated product, unrecovered lead remained at concentrations of 0.25-0.79 wt%. When the Na2CO3 dosage in the thermal treatment was increased, the lead removal by acid leaching was enhanced, and the lead concentration in the obtained product decreased to 0.016 wt%.

  17. Factors influencing leaching of PBDEs from waste cathode ray tube plastic housings.

    PubMed

    Stubbings, William A; Harrad, Stuart

    2016-11-01

    Samples of waste cathode ray tube (CRT) plastic housings were exposed to Milli-Q® water containing dissolved humic matter at concentrations of 0, 100 and 1000mgL(-1) as leaching fluid under laboratory conditions, and polybrominated diphenyl ethers (PBDEs) determined in the resulting leachate. Despite the relatively hydrophobic physicochemical properties of PBDEs, concentrations of ƩPBDEs in the leachate from the leaching experiments in this study ranged from 14,000 to 200,000ngL(-1). PBDE leaching appears to be a second order process, whereby a period of initially intense dissolution of more labile PBDEs is followed by a slower stage corresponding to external diffusion of the soluble residue in the material. The bulk of transfer of PBDEs to the leaching fluid occurs within the first 6h of contact, during which time we suggest that the most labile PBDEs are "washed" off the surface of the CRT plastics. The predominant congeners in the chips were BDE-209 (2600mgkg(-1)) and BDE 183 (220mgkg(-1)). The impacts on PBDE leaching of leachate pH and temperature were also examined. Increasing the temperature of leaching fluids from 20 to 80°C, enhances the leachability of BDE-209 and BDE-99 from plastics. In all cases, the alkaline pH8.5 examined, resulted in the greatest PBDE concentrations in leachate. Agitation of the waste/leachate mixture enhances PBDE leaching from CRT plastics. Potential evidence for debromination of heavy congeners to the lower brominated and more bioavailable BDEs was observed. Specifically, BDEs-47, -85 and -100 were detected in the leachates, but were absent from the CRT plastics themselves. PMID:27436776

  18. Removal of lead from cathode ray tube funnel glass by generating the sodium silicate.

    PubMed

    Hu, Biao; Zhao, Shuangshuang; Zhang, Shuhao

    2015-01-01

    In the disposal of electronic waste, cathode ray tube (CRT) funnel glass is an environmental problem of old television sets. Removal of the lead from CRT funnel glass can prevent its release into the environment and allow its reuse. In this research, we reference the dry progress productive technology of sodium silicate, the waste CRT glass was dealt with sodium silicate frit melted and sodium silicate frit dissolved. Adding a certain amount of Na ₂CO₃to the waste CRT glass bases on the material composition and content of it, then the specific modulus of sodium silicate frit is obtained by melting progress. The silicon, potassium and sodium compounds of the sodium silicate frit are dissolved under the conditions of high temperature and pressure by using water as solvent, which shows the tendency that different temperature, pressure, liquid-solid ratio and dissolving time have effect on the result of dissolving. At 175°C(0.75MPa), liquid-solid ratio is 1.5:1, the dissolving time is 1h, the dissolution rate of sodium silicate frit is 44.725%. By using sodium sulfide to separate hydrolysis solution and to collect lead compounds in the solution, the recovery rate of lead in dissolving reached 100% and we can get clean sodium silicate and high purity of lead compounds. The method presented in this research can recycle not only the lead but also the sodium, potassium and other inorganic minerals in CRT glass and can obtain the comprehensive utilization of leaded glass.

  19. Removal of lead from cathode ray tube funnel glass by generating the sodium silicate.

    PubMed

    Hu, Biao; Zhao, Shuangshuang; Zhang, Shuhao

    2015-01-01

    In the disposal of electronic waste, cathode ray tube (CRT) funnel glass is an environmental problem of old television sets. Removal of the lead from CRT funnel glass can prevent its release into the environment and allow its reuse. In this research, we reference the dry progress productive technology of sodium silicate, the waste CRT glass was dealt with sodium silicate frit melted and sodium silicate frit dissolved. Adding a certain amount of Na ₂CO₃to the waste CRT glass bases on the material composition and content of it, then the specific modulus of sodium silicate frit is obtained by melting progress. The silicon, potassium and sodium compounds of the sodium silicate frit are dissolved under the conditions of high temperature and pressure by using water as solvent, which shows the tendency that different temperature, pressure, liquid-solid ratio and dissolving time have effect on the result of dissolving. At 175°C(0.75MPa), liquid-solid ratio is 1.5:1, the dissolving time is 1h, the dissolution rate of sodium silicate frit is 44.725%. By using sodium sulfide to separate hydrolysis solution and to collect lead compounds in the solution, the recovery rate of lead in dissolving reached 100% and we can get clean sodium silicate and high purity of lead compounds. The method presented in this research can recycle not only the lead but also the sodium, potassium and other inorganic minerals in CRT glass and can obtain the comprehensive utilization of leaded glass. PMID:25946963

  20. Factors influencing leaching of PBDEs from waste cathode ray tube plastic housings.

    PubMed

    Stubbings, William A; Harrad, Stuart

    2016-11-01

    Samples of waste cathode ray tube (CRT) plastic housings were exposed to Milli-Q® water containing dissolved humic matter at concentrations of 0, 100 and 1000mgL(-1) as leaching fluid under laboratory conditions, and polybrominated diphenyl ethers (PBDEs) determined in the resulting leachate. Despite the relatively hydrophobic physicochemical properties of PBDEs, concentrations of ƩPBDEs in the leachate from the leaching experiments in this study ranged from 14,000 to 200,000ngL(-1). PBDE leaching appears to be a second order process, whereby a period of initially intense dissolution of more labile PBDEs is followed by a slower stage corresponding to external diffusion of the soluble residue in the material. The bulk of transfer of PBDEs to the leaching fluid occurs within the first 6h of contact, during which time we suggest that the most labile PBDEs are "washed" off the surface of the CRT plastics. The predominant congeners in the chips were BDE-209 (2600mgkg(-1)) and BDE 183 (220mgkg(-1)). The impacts on PBDE leaching of leachate pH and temperature were also examined. Increasing the temperature of leaching fluids from 20 to 80°C, enhances the leachability of BDE-209 and BDE-99 from plastics. In all cases, the alkaline pH8.5 examined, resulted in the greatest PBDE concentrations in leachate. Agitation of the waste/leachate mixture enhances PBDE leaching from CRT plastics. Potential evidence for debromination of heavy congeners to the lower brominated and more bioavailable BDEs was observed. Specifically, BDEs-47, -85 and -100 were detected in the leachates, but were absent from the CRT plastics themselves.

  1. Environmental burdens in the management of end-of-life cathode ray tubes.

    PubMed

    Rocchetti, Laura; Beolchini, Francesca

    2014-02-01

    We compared the environmental burdens in the management of end-of life cathode ray tubes (CRTs) within two frameworks according to the different technologies of the production of televisions/monitors. In the first case, CRT recycling is addressed to the recovery of the panel and funnel glass for the manufacturing of new CRT screens. In the second case, where flat screen technology has replaced that of CRT, the recycling is addressed to the recovery of the glass cullet and lead for other applications. The impacts were evaluated according to the problem-oriented methodology of the Institute of Environmental Sciences, Leiden University, Leiden, The Netherlands. Our data confirm that in both cases, the recycling treatment allows benefits to be gained for the environment through the recovery of the secondary raw materials. These benefits are higher for the "CRT technology" framework (1 kg CO2 saved per CRT) than for the "flat screen technology" (0.9 kg CO2 saved, per CRT, as the highest possible), mainly due to the high energy consumption for lead separation from the funnel glass. Furthermore, the recovery of yttrium from the fluorescent powders that are a residue of the recycling treatment would further improve the CO2 credit for both the frameworks considered, which would provide a further saving of about 0.75 kg CO2 per CRT, net of the energy and raw materials needed for the recovery. Overall, this study confirms that, even with a change in the destination of the recovered materials, the recycling processes provide a benefit for the environment: indeed the higher loads for the environment are balanced by avoiding the primary production of the recovered materials.

  2. Protein-Support Interactions for Rationally Designed Bilirubin Oxidase Based Cathode: A Computational Study.

    PubMed

    Matanovic, Ivana; Babanova, Sofia; Chavez, Madelaine Seow; Atanassov, Plamen

    2016-04-21

    An example of biocathode based on bilirubin oxidase (BOx) was used to demonstrate how density functional theory can be combined with docking simulations in order to study the interface interactions between the enzyme and specifically designed electrode surface. The electrode surface was modified through the adsorption of bilirubin, the natural substrate for BOx, and the prepared electrode was electrochemically characterized using potentiostatic measurements. The experimentally determined current densities showed that the presence of bilirubin led to significant improvement of the cathode operation. On the basis of the computationally calculated binding energies of bilirubin to the graphene support and BOx and the analysis of the positioning of bilirubin relative to the support and T1 Cu atom of the enzyme, we hypothesize that the bilirubin serves as a geometric and electronic extension of the support. The computational results further confirm that the modification of the electrode surface with bilirubin provides an optimal orientation of BOx toward the support but also show that bilirubin facilitates the interfacial electron transfer by decreasing the distance between the electrode surface and the T1 Cu atom. PMID:27015361

  3. First principle computational and experimental studies of cathode materials for lithium ion rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Saavedra Arias, Jose Javier

    We have studied the properties of spinel and layered cathode materials for Li ion rechargeable batteries. The analysis was done by first principle calculations, and experimental techniques to elucidate materials that can substitute the presently commercialized material, namely LiCoO 2. We have studied the influence of Ni substitution for Mn in spinel Li 2MnO4. To understand the effects of this substitution on the crystal structure and electronic properties, first principle DFT calculations were performed using VASP. The substitution was done systematically for up to 25% of Mn replacement by Ni in a super cell configuration. Furthermore, the influence of Ni substitution on lithium hoping pathways between the two stable Li positions was also studied by first principle calculations in LiMn 2-xNixO4. These calculations revealed that Ni substitution for Mn in LiMn2O4 indeed improved Li ion mobility. Thereafter, systematic experimental studies were performed on LiMn 2-xNixO4 (0ray diffraction (XRD) and Raman spectroscopy. The electrochemical performance of LiMn2-xNi xO4 materials was evaluated in two electrode CR2032 type coin cell configuration with Li metal as anode and liquid electrolyte (1 M LiPF6 in EC:DMC=1:1 v/v). Our results showed significant enhancement in the electrochemical properties with 25% of Ni substitution in LiMn 2O4, which is in good agreement with the theoretical calculations. We also studied layered cathode materials both theoretically and experimentally. The First principle calculations in conjunction with alloy metal method were used to evaluate the average voltage and phase stability of LiMO2 (M=Co, Ni, Mn, W) systems. By formation energy analysis we established that LiNi0.8Co0.1Mn0.1O2 is a promising candidate cathode material. Single

  4. Design of a High Field Stress, Velvet Cathode for the Flash X-Ray (FXR) Induction Accelerator

    SciTech Connect

    Houck, T; Brown, C; Fleming, D; Kreitzer, B; Lewis, K; Ong, M; Zentler, J

    2007-06-08

    A new cathode design has been proposed for the Flash X-Ray (FXR) induction linear accelerator with the goal of lowering the beam emittance. The original design uses a conventional Pierce geometry and applies a peak field of 134 kV/cm (no beam) to the velvet emission surface. Voltage/current measurements indicate that the velvet begins emitting near this peak field value and images of the cathode show a very non-uniform distribution of plasma light. The new design has a flat cathode/shroud profile that allows for a peak field stress of 230 kV/cm on the velvet. The emission area is reduced by about a factor of four to generate the same total current due to the greater field stress. The relatively fast acceleration of the beam, approximately 2.5 MeV in 10 cm, reduces space charge forces that tend to hollow the beam for a flat, non-Pierce geometry. The higher field stress achieved with the same rise time is expected to lead to an earlier and more uniform plasma formation over the velvet surface. Simulations and initial testing are presented.

  5. Study of Explosive Electron Emission from a Pin Cathode Using High Resolution Point-Projection X-Ray Radiography

    NASA Astrophysics Data System (ADS)

    Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Parkevich, E. V.; Tilikin, I. N.; Mingaleev, A. R.; Agafonov, A. V.

    2015-11-01

    Most studies of Explosive Electron Emission (EEE) are based on the idea of cathode flares developing after explosion of metal whiskers (micron scale pins) on the cathode surface. The physical state of the pin material, the spatial structure of the explosion and its origin are still a matter of conjecture. In this work we used high-resolution point projection x-ray radiography to observe micron scale pin explosion in a high-current diode. Pin cathodes made from 10-25 micron Cu or Mo wires were placed in gaps in return current circuits of hybrid X-pinches on the XP and BIN pulsers. Pin lengths were varied over a range 1-4 mm and pin-anode gaps within 0.05-3 mm. The diode current and voltage were measured. In experiments with small pin-anode gap (0.1 - 1 mm) development of an expanded dense core of the pin was observed except the pin tip with length 100-200 microns indicating significant energy deposition in the wire material. In experiments with bigger gaps there was no visible wire core expansion within the spatial resolution of the experimental technique. Work at Cornell was supported by the National Nuclear Security Administration Stewardship Sciences Academic Programs under Department of Energy Cooperative Agreement No. DE-NA0001836 and at the Lebedev Institute by the RSF grant 142200273.

  6. Environmental burdens in the management of end-of-life cathode ray tubes

    SciTech Connect

    Rocchetti, Laura; Beolchini, Francesca

    2014-02-15

    Highlights: • The paper deals with different management options for end-of-life CRTs. • The environmental burdens for disposal and recycling are presented. • Recycling treatments allows to gain benefits for the environment. • Further treatments for fluorescent powders determine CO{sub 2} credits. • More efforts should be directed towards recycling. - Abstract: We compared the environmental burdens in the management of end-of life cathode ray tubes (CRTs) within two frameworks according to the different technologies of the production of televisions/monitors. In the first case, CRT recycling is addressed to the recovery of the panel and funnel glass for the manufacturing of new CRT screens. In the second case, where flat screen technology has replaced that of CRT, the recycling is addressed to the recovery of the glass cullet and lead for other applications. The impacts were evaluated according to the problem-oriented methodology of the Institute of Environmental Sciences, Leiden University, Leiden, The Netherlands. Our data confirm that in both cases, the recycling treatment allows benefits to be gained for the environment through the recovery of the secondary raw materials. These benefits are higher for the “CRT technology” framework (1 kg CO{sub 2} saved per CRT) than for the “flat screen technology” (0.9 kg CO{sub 2} saved, per CRT, as the highest possible), mainly due to the high energy consumption for lead separation from the funnel glass. Furthermore, the recovery of yttrium from the fluorescent powders that are a residue of the recycling treatment would further improve the CO{sub 2} credit for both the frameworks considered, which would provide a further saving of about 0.75 kg CO{sub 2} per CRT, net of the energy and raw materials needed for the recovery. Overall, this study confirms that, even with a change in the destination of the recovered materials, the recycling processes provide a benefit for the environment: indeed the higher loads

  7. Offshore cathodic protection design, inspection, and computer modeling: Innovations from the 1980s

    SciTech Connect

    Gartland, P.O.; Strommen, R.D.; Osvoll, H.; Johnsen, R. )

    1993-12-01

    Throughout the 1980s, equipment was used increasingly to monitor electric fields (EF) strength/current density in CP surveys of North Sea structures. Probes for remote-operated vehicle (ROV) and diver operations are used to measure simultaneously the potential and the EF strength at exposed steel, at typical stand-off anodes, at sacrificial bracelet anodes on pipelines, and so on. A sensitive system for such purposes is based on a pair of electrodes at the tips of a T-shaped spindle rotating at a known frequency. The 1980s saw several innovations in the field of offshore cathodic protection (CP). The increasing use of organic coatings on offshore structures is more or less a result of the need to reduce the number of anodes. In a design incorporating coatings, coating breakdown plays a key role. In later years, aluminum-coated structures have been introduced for submerged conditions. It seems that in the future, aluminum coatings will be used merely as barrier coatings. The bare aluminum coating has a very low current demand on the order or 10 mA/m[sup 2] or less. Emphasis is now on CP design by computer modeling and on data retrieved during inspections using sophisticated equipment and procedures. The effect of the innovations on traditional design, on design verification, and on retrofitting is discussed in relation to relevant cases and field work. Future applications that may give better insight into CP system performance at reduced cost are also suggested.

  8. Optical profiles of cathode ray tube and liquid crystal display monitors: implication in cutaneous phototoxicity in photodynamic therapy

    PubMed Central

    Lei, Tim C.; Pendyala, Srinivas; Scherrer, Larry; Li, Buhong; Glazner, Gregory F.; Huang, Zheng

    2016-01-01

    Recent clinical reports suggest that overexposure to light emissions generated from cathode ray tube (CRT) and liquid crystal display (LCD) color monitors after topical or systemic administration of a photosensitizer could cause noticeable skin phototoxicity. In this study, we examined the light emission profiles (optical irradiance, spectral irradiance) of CRT and LCD monitors under simulated movie and video game modes. Results suggest that peak emissions and integrated fluence generated from monitors are clinically relevant and therefore prolonged exposure to these light sources at a close distance should be avoided after the administration of a photosensitizer or phototoxic drug. PMID:23669681

  9. A Century-Old Question: Does a Crookes Paddle Wheel Cathode Ray Tube Demonstrate that Electrons Carry Momentum?

    NASA Astrophysics Data System (ADS)

    Humphrey, T. E.; Calisa, Vaishnavi

    2014-03-01

    In 1879, in the midst of the debate between English and continental scientists about the nature of cathode rays, William Crookes conducted an experiment in which a small mill or "paddle wheel" was pushed along tracks inside a cathode ray tube (CRT) (similar to that shown in Fig. 1) when connected to a high-voltage induction coil. Crookes attributed the motion of the wheel to momentum transfer from the cathode rays (electrons) to the wheel, and interpreted the experiment as providing evidence that cathode rays were particles. In 1903 Thomson discounted Crookes' interpretation by calculating that the rate of momentum transfer (which he estimated at no more than 2×10-3 dyn, equivalent to 2×10-8 N) would be far too small to account for the observed motion of the wheel,2 instead attributing the motion to the radiometric effect. The misconception was not laid to rest, however, and despite an effort in 1961 to draw attention to Thomson's original work and so remove the error from textbooks,3 the notion that a Crookes paddle wheel CRT demonstrates that electrons carry momentum continues to be taught in high school physics courses4 and wheel. We then measured the actual acceleration of the wheel in the CRT by video analysis of its motion and determined the moment of inertia of the wheel along with its mass and dimensions. We could then compare the force, which really acts on the wheel to produce the observed motion to the maximum impulsive force that is supplied by the electrons. Our measurements yield a maximum impulsive force due to the electrons [ F e l = ( 1.1 ± 0.3 ) × 10 - 8 N ], which is within a factor of two of Thomson's estimate, and which is more than two orders of magnitude smaller than the force that is responsible for the observed acceleration of the paddle wheel [ F W = ( 6 ± 2 ) × 10 - 6 N ]. This means that the rotation of the wheel is certainly not due to transferred momentum from the electron beam, and the results of the experiment should not be

  10. Optical profiles of cathode ray tube and liquid crystal display monitors: implication in cutaneous phototoxicity in photodynamic therapy.

    PubMed

    Lei, Tim C; Pendyala, Srinivas; Scherrer, Larry; Li, Buhong; Glazner, Gregory F; Huang, Zheng

    2013-04-20

    Recent clinical reports suggest that overexposure to light emissions generated from cathode ray tube (CRT) and liquid crystal display (LCD) color monitors after topical or systemic administration of a photosensitizer could cause noticeable skin phototoxicity. In this study, we examined the light emission profiles (optical irradiance, spectral irradiance) of CRT and LCD monitors under simulated movie and video game modes. Results suggest that peak emissions and integrated fluence generated from monitors are clinically relevant and therefore prolonged exposure to these light sources at a close distance should be avoided after the administration of a photosensitizer or phototoxic drug.

  11. Three-dimensional X-ray microcomputed tomography of carbonates and biofilm on operated cathode in single chamber microbial fuel cell.

    PubMed

    Santini, Maurizio; Guilizzoni, Manfredo; Lorenzi, Massimo; Atanassov, Plamen; Marsili, Enrico; Fest-Santini, Stephanie; Cristiani, Pierangela; Santoro, Carlo

    2015-09-10

    Power output limitation is one of the main concerns that need to be addressed for full-scale applications of the microbial fuel cell technology. Fouling and biofilm growth on the cathode of single chamber microbial fuel cells (SCMFC) affects their performance in long-term operation with wastewater. In this study, the authors report the power output and cathode polarization curves of a membraneless SCMFC, fed with raw primary wastewater and sodium acetate for over 6 months. At the end of the experiment, the whole cathode surface is analyzed through X-ray microcomputed tomography (microCT), scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDX) to characterize the fouling layer and the biofilm. EDX shows the distribution of Ca, Na, K, P, S, and other elements on the two faces of the cathode. Na-carbonates and Ca-carbonates are predominant on the air (outer) side and the water (inner) side, respectively. The three-dimensional reconstruction by X-ray microCT shows biofilm spots unevenly distributed above the Ca-carbonate layer on the inner (water) side of the cathode. These results indicate that carbonates layer, rather than biofilm, might lower the oxygen reduction reaction rate at the cathode during long-term SCMFC operation.

  12. U-shape rotating anti-cathode compact X-ray generator: 20 times stronger than the commercially available X-ray source.

    PubMed

    Sakabe, N; Sakabe, K; Ohsawa, S; Sakai, T; Kobayakawa, H; Sugimura, T; Ikeda, M; Tawada, M; Watanabe, N; Sasaki, K; Wakatsuki, M

    2013-11-01

    A new type of U-shape anti-cathode X-ray generator in which the inner surface of a cylindrical target is irradiated by an electron beam has been made by modifying a conventional rotating anti-cathode X-ray generator whose brightness in the catalog is 12 kW mm(-2). The target material (Cu), target radius (50 mm) and rotating speed (6,000 r.p.m.) were not changed in this modification. A brightness of 52 kW mm(-2) was obtained by this U-shape-type X-ray generator. This means that the brightness of the new type is 4.3 times greater than that of the old unmodified one. Furthermore, the new-type X-ray generator yielded a brightness of 129 kW mm(-2) by adding a carbon coating on the Cu target. This means an overall increase of brightness of ten times. The original generator has the highest brightness in the generators of the same class (having a radius of 50 mm and rotation speed of 6,000 r.p.m.). Observations showed that Cu Kα counts at vertical incidence of the electron beam onto the surface of the new target, which is initially optically smooth, decrease as the surface is roughened by a severe thermal stress caused by strong electron beam exposure. Further observation reveals, however, that oblique incidence of the electron beam onto the roughened surface drastically increased the X-ray output and amounts to twice as much as that from a smooth surface at vertical incidence. Thus, at the present stage, an overall increase of brightness has been realised at a level 20 times stronger than that of the original commercially offered X-ray generator that we modified.

  13. Utilization of cathode ray tube waste: encapsulation of PbO-containing funnel glass in Portland cement clinker.

    PubMed

    Lairaksa, Nirut; Moon, Anthony R; Makul, Natt

    2013-03-15

    The disposal of cathode ray tube (CRT) generates large quantities of leaded glass waste. The encapsulation of glass from the funnel portion of CRT in cement clinker was investigated. Samples of cement raw material containing 0 (control), 0.1, 0.2, 0.3, 0.4, or 0.5 wt% of CRT funnel glass ground to less than 75 μm were heated to 1480 °C in an electric furnace for 1.5 h at a heating rate of 5 °C/min to produce cement clinker. The Pb encapsulation and chemical composition of the clinkers were analysed using X-ray techniques and atomic absorption spectroscopy (AAS). The maximum PbO encapsulation occurred in mixtures containing 0.1 wt% funnel glass.

  14. Proceedings of the workshop on X-ray computed microtomography

    SciTech Connect

    1998-02-01

    This report consists of vugraphs from the nine presentations at the conference. Titles of the presentations are: CMT: Applications and Techniques; Computer Microtomography Using X-rays from Third Generation Synchrotron X-ray; Approaches to Soft-X-ray Nanotomography; Diffraction Enhanced Tomography; X-ray Computed Microtomography Applications at the NSLS; XCMT Applications in Forestry and Forest Products; 3DMA: Investigating Three Dimensional Pore Geometry from High Resolution Images; X-ray Computed Microtomography Studies of Volcanic Rock; and 3-D Visualization of Tomographic Volumes.

  15. Electronic structure of the polymer-cathode interface of an organic electroluminescent device investigated using operando hard x-ray photoelectron spectroscopy

    SciTech Connect

    Ikeuchi, J.; Hamamatsu, H.; Miyamoto, T.; Tanaka, S.; Yamashita, Y.; Yoshikawa, H.; Ueda, S.

    2015-08-28

    The electronic structure of a polymer-cathode interface of an operating organic light-emitting diode (OLED) was directly investigated using hard X-ray photoelectron spectroscopy (HAXPES). The potential distribution profile of the light-emitting copolymer layer as a function of the depth under the Al/Ba cathode layer in the OLED depended on the bias voltage. We found that band bending occurred in the copolymer of 9,9-dioctylfluorene (50%) and N-(4-(2-butyl)-phenyl)diphenylamine (F8-PFB) layer near the cathode at 0 V bias, while a linear potential distribution formed in the F8-PFB when a bias voltage was applied to the OLED. Direct observation of the built-in potential and that band bending formed in the F8-PFB layer in the operating OLED suggested that charges moved in the F8-PFB layer before electron injection from the cathode.

  16. REVIEW: X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Kalender, Willi A.

    2006-07-01

    X-ray computed tomography (CT), introduced into clinical practice in 1972, was the first of the modern slice-imaging modalities. To reconstruct images mathematically from measured data and to display and to archive them in digital form was a novelty then and is commonplace today. CT has shown a steady upward trend with respect to technology, performance and clinical use independent of predictions and expert assessments which forecast in the 1980s that it would be completely replaced by magnetic resonance imaging. CT not only survived but exhibited a true renaissance due to the introduction of spiral scanning which meant the transition from slice-by-slice imaging to true volume imaging. Complemented by the introduction of array detector technology in the 1990s, CT today allows imaging of whole organs or the whole body in 5 to 20 s with sub-millimetre isotropic resolution. This review of CT will proceed in chronological order focussing on technology, image quality and clinical applications. In its final part it will also briefly allude to novel uses of CT such as dual-source CT, C-arm flat-panel-detector CT and micro-CT. At present CT possibly exhibits a higher innovation rate than ever before. In consequence the topical and most recent developments will receive the greatest attention.

  17. Reddish Orange Long-Lasting Phosphorescence in KY3F10:Sm3+ for X-Ray or Cathode Ray Tubes

    NASA Astrophysics Data System (ADS)

    Zhang, Jin-Su; Zhong, Hai-Yang; Sun, Jia-Shi; Cheng, Li-Hong; Li, Xiang-Ping; Chen, Bao-Jiu

    2012-01-01

    We report a reddish orange long-lasting phosphor of KY3F10:Sm3+ synthesized by a solid-state reaction for applications in x-ray or cathode-ray tubes. The spectrum contains a group of reddish orange emission lines originating from 4G5/2 → 6HJ transitions of Sm3+. The Judd—Ofelt theory is introduced to analyze the optical transitions of the Sm3+ ions. Moreover, phosphorescence characteristics are discussed. The energy charging and release processes of the phosphor are measured and the phosphorescence decay time with 10% of initial intensity is about 40.7 seconds. The order of kinetics and the activation energy are obtained according to the thermoluminescence curve. The phosphorescence mechanism is proposed based on structural analysis and thermoluminescence glow curve measurement.

  18. A tetrahedron beam computed tomography benchtop system with a multiple pixel field emission x-ray tube

    SciTech Connect

    Xu, Xiaochao; Kim, Joshua; Laganis, Philip; Schulze, Derek; Liang, Yongguang; Zhang, Tiezhi

    2011-10-15

    Purpose: To demonstrate the feasibility of Tetrahedron Beam Computed Tomography (TBCT) using a carbon nanotube (CNT) multiple pixel field emission x-ray (MPFEX) tube. Methods: A multiple pixel x-ray source facilitates the creation of novel x-ray imaging modalities. In a previous publication, the authors proposed a Tetrahedron Beam Computed Tomography (TBCT) imaging system which comprises a linear source array and a linear detector array that are orthogonal to each other. TBCT is expected to reduce scatter compared with Cone Beam Computed Tomography (CBCT) and to have better detector performance. Therefore, it may produce improved image quality for image guided radiotherapy. In this study, a TBCT benchtop system has been developed with an MPFEX tube. The tube has 75 CNT cold cathodes, which generate 75 x-ray focal spots on an elongated anode, and has 4 mm pixel spacing. An in-house-developed, 5-row CT detector array using silicon photodiodes and CdWO{sub 4} scintillators was employed in the system. Hardware and software were developed for tube control and detector data acquisition. The raw data were preprocessed for beam hardening and detector response linearity and were reconstructed with an FDK-based image reconstruction algorithm. Results: The focal spots were measured at about 1 x 2 mm{sup 2} using a star phantom. Each cathode generates around 3 mA cathode current with 2190 V gate voltage. The benchtop system is able to perform TBCT scans with a prolonged scanning time. Images of a commercial CT phantom were successfully acquired. Conclusions: A prototype system was developed, and preliminary phantom images were successfully acquired. MPFEX is a promising x-ray source for TBCT. Further improvement of tube output is needed in order for it to be used in clinical TBCT systems.

  19. Rapid screening of different chelating agents in the lead extraction from cathode ray tube (CRT) funnel glass.

    PubMed

    Barbieri, Luisa; Lancellotti, Isabella; Ponzoni, Chiara

    2014-12-01

    The cathode ray tube (CRT) glass is one of the most important problem that afflicts the electronic waste disposal whose solution lies in the identification of efficient and ecofriendly processes to detoxify and reutilize lead-contained funnel glass. This study is focused on a rapid screening of different chemical and mechanochemical processes to reduce lead content in waste CRT glass downgrading the risk correlated to it. In particular, as a possibility to clean waste CRT glass, treatments of lead-containing glass with different chelating agents (EDTA, NTA, ATMP, EDTMP and HEDP) were performed to evaluate their extractive capabilities. Furthermore, the influence of the grinding, the chelating agent functional groups (polyamino-carboxylic acid, carboxylic acid, and polyamino phosphonic acid), and the time and the temperature on lead content reduction were analyzed. ESEM and EDS analysis were performed on all the samples to evaluate the lead amount before and after the treatments.

  20. Dose in x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Kalender, Willi A.

    2014-02-01

    Radiation dose in x-ray computed tomography (CT) has become a topic of high interest due to the increasing numbers of CT examinations performed worldwide. This review aims to present an overview of current concepts for both scanner output metrics and for patient dosimetry and will comment on their strengths and weaknesses. Controversial issues such as the appropriateness of the CT dose index (CTDI) are discussed in detail. A review of approaches to patient dose assessment presently in practice, of the dose levels encountered and options for further dose optimization are also given and discussed. Patient dose assessment remains a topic for further improvement and for international consensus. All approaches presently in use are based on Monte Carlo (MC) simulations. Estimates for effective dose are established, but they are crude and not patient-specific; organ dose estimates are rarely available. Patient- and organ-specific dose estimates can be provided with adequate accuracy and independent of CTDI phantom measurements by fast MC simulations. Such information, in particular on 3D dose distributions, is important and helpful in optimization efforts. Dose optimization has been performed very successfully in recent years and even resulted in applications with effective dose values of below 1 mSv. In general, a trend towards lower dose values based on technical innovations has to be acknowledged. Effective dose values are down to clearly below 10 mSv on average, and there are a number of applications such as cardiac and pediatric CT which are performed routinely below 1 mSv on modern equipment.

  1. Energy-efficient modification of reduction-melting for lead recovery from cathode ray tube funnel glass

    SciTech Connect

    Okada, Takashi Yonezawa, Susumu

    2013-08-15

    Highlights: • We recovered Pb from cathode ray tube funnel glass using reduction melting process. • We modified the melting process to achieve Pb recovery with low energy consumption. • Pb in the funnel glass is efficiently recovered at 1000 °C by adding Na{sub 2}CO{sub 3}. • Pb remaining in the glass after reduction melting is extracted with 1 M HCl. • 98% of Pb in the funnel glass was recovered by reduction melting and HCl leaching. - Abstract: Lead can be recovered from funnel glass of waste cathode ray tubes via reduction melting. While low-temperature melting is necessary for reduced energy consumption, previously proposed methods required high melting temperatures (1400 °C) for the reduction melting. In this study, the reduction melting of the funnel glass was performed at 900–1000 °C using a lab-scale reactor with varying concentrations of Na{sub 2}CO{sub 3} at different melting temperatures and melting times. The optimum Na{sub 2}CO{sub 3} dosage and melting temperature for efficient lead recovery was 0.5 g per 1 g of the funnel glass and 1000 °C respectively. By the reduction melting with the mentioned conditions, 92% of the lead in the funnel glass was recovered in 60 min. However, further lead recovery was difficult because the rate of the lead recovery decreased as with the recovery of increasing quantity of the lead from the glass. Thus, the lead remaining in the glass after the reduction melting was extracted with 1 M HCl, and the lead recovery improved to 98%.

  2. Dosimetry comparison and characterisation of an Al K ultrasoft x-ray beam from an MRC cold-cathode source.

    PubMed

    Hoshi, M; Goodhead, D T; Brenner, D J; Bance, D A; Chmielewski, J J; Paciotti, M A; Bradbury, J N

    1985-10-01

    Ultrasoft x-rays of 0.3-5 keV have provided a unique tool for the investigation of intracellular mechanisms of radiation action in biological organisms, including mammalian cells. However, their use presents unique practical problems in dosimetry and experimental design. Detailed interpretation of the biological results requires reliable dosimetry and well characterised monoenergetic beams. This paper presents a comparison between two fundamentally different dosimetric techniques, namely the ionisation current in an extrapolation chamber and photon counts in a proportional counter. Agreement within 7% was obtained when these two methods were applied to an Al K x-ray beam (1.5 keV) from an MRC cold-cathode transmission target discharge tube as previously used in many biological experiments. Photographic film was calibrated as a relative dosimetric technique and used for investigation of the intensity uniformity of the radiation field. These techniques provide a comprehensive characterisation of the beam in the position of the biological cells, including photon flux (or absorbed dose rate), spectral purity (showing much less than 1% bremsstrahlung relative to characteristic Al x-rays) and uniformity over the irradiation area (within about 5% for mammalian cell irradiations).

  3. Solid Electrolyte/Electrode Interfaces: Atomistic Behavior Analyzed Via UHV-AFM, Surface Spectroscopies, and Computer Simulations Computational and Experimental Studies of the Cathode/Electrolyte Interface in Oxide Thin Film Batteries

    SciTech Connect

    Garofalini, Stephen H

    2012-03-21

    The goals of the research were to understand the structural, dynamic, and chemical properties of solid electrolyte surfaces and the cathode/electrolyte interface at an atomistic and nanometer level using both computational and experimental techniques.

  4. Opportunities for X-ray Science in Future Computing Architectures

    SciTech Connect

    Foster, Ian

    2011-02-09

    The world of computing continues to evolve rapidly. In just the past 10 years, we have seen the emergence of petascale supercomputing, cloud computing that provides on-demand computing and storage with considerable economies of scale, software-as-a-service methods that permit outsourcing of complex processes, and grid computing that enables federation of resources across institutional boundaries. These trends show no sign of slowing down. The next 10 years will surely see exascale, new cloud offerings, and other terabit networks. This talk reviews various of these developments and discusses their potential implications for x-ray science and x-ray facilities.

  5. Computer Graphics.

    ERIC Educational Resources Information Center

    Halpern, Jeanne W.

    1970-01-01

    Computer graphics have been called the most exciting development in computer technology. At the University of Michigan, three kinds of graphics output equipment are now being used: symbolic printers, line plotters or drafting devices, and cathode-ray tubes (CRT). Six examples are given that demonstrate the range of graphics use at the University.…

  6. PRELIMINARY IN-SITU X-RAY ABSORPTION FINE STRUCTURE EXAMINATION OF PT/C AND PTCO/C CATHODE CATALYSTS IN AN OPERATIONAL POLYMER ELECTROLYTE FUEL CELL

    SciTech Connect

    Phelan, B.T.; Myers, D.J.; Smith, M.C.

    2009-01-01

    State-of-the-art polymer electrolyte fuel cells require a conditioning period to reach optimized cell performance. There is insuffi cient understanding about the behavior of catalysts during this period, especially with regard to the changing environment of the cathode electrocatalyst, which is typically Pt nanoparticles supported on high surface area Vulcan XC-72 carbon (Pt/C). The purpose of this research was to record preliminary observations of the changing environment during the conditioning phase using X-Ray Absorption Fine Structure (XAFS) spectroscopy. XAFS was recorded for a Pt/C cathode at the Pt L3-edge and a PtCo/C cathode at both the Pt L3-edge and Co K-edge. Using precision machined graphite cell-blocks, both transmission and fl uorescence data were recorded at Sector 12-BM-B of Argonne National Laboratory’s Advanced Photon Source. The fl uorescence and transmission edge steps allow for a working description of the changing electrocatalyst environment, especially water concentration, at the anode and cathode as functions of operating parameters. These features are discussed in the context of how future analysis may correlate with potential, current and changing apparent thickness of the membrane electrode assembly through loss of catalyst materials (anode, cathode, carbon support). Such direct knowledge of the effect of the conditioning protocol on the electrocatalyst may lead to better catalyst design. In turn, this may lead to minimizing, or even eliminating, the conditioning period.

  7. Detection efficiency vs. cathode and anode separation in cylindrical vacuum photodiodes used for measuring x-rays from plasma focus device

    NASA Astrophysics Data System (ADS)

    Borthakur, T. K.; Talukdar, N.; Neog, N. K.; Rao, C. V. S.; Shyam, A.

    2011-10-01

    A qualitative study on the performance of cylindrical vacuum photodiodes (VPDs) for x-ray detection in plasma focus device has been carried out. Various parameters of VPD such as electrode's diameter, electrode's separation, and its sensitivity are experimentally tested in plasma focus environment. For the first time it is found experimentally that the electrode-separation in the lateral direction of the two coaxial electrodes of cylindrical VPD also plays an important role to increase the efficiency of the detector. The efficiency is found to be highest for the detector with smaller cathode-anode lateral gap (1.5 mm) with smaller photo cathode diameter (10 mm). A comparison between our VPD with PIN (BPX-65) diode as an x-ray detector has also been made.

  8. Detection efficiency vs. cathode and anode separation in cylindrical vacuum photodiodes used for measuring x-rays from plasma focus device.

    PubMed

    Borthakur, T K; Talukdar, N; Neog, N K; Rao, C V S; Shyam, A

    2011-10-01

    A qualitative study on the performance of cylindrical vacuum photodiodes (VPDs) for x-ray detection in plasma focus device has been carried out. Various parameters of VPD such as electrode's diameter, electrode's separation, and its sensitivity are experimentally tested in plasma focus environment. For the first time it is found experimentally that the electrode-separation in the lateral direction of the two coaxial electrodes of cylindrical VPD also plays an important role to increase the efficiency of the detector. The efficiency is found to be highest for the detector with smaller cathode-anode lateral gap (1.5 mm) with smaller photo cathode diameter (10 mm). A comparison between our VPD with PIN (BPX-65) diode as an x-ray detector has also been made. PMID:22047294

  9. Extraction of metallic lead from cathode ray tube (CRT) funnel glass by thermal reduction with metallic iron.

    PubMed

    Lu, Xingwen; Shih, Kaimin; Liu, Chengshuai; Wang, Fei

    2013-09-01

    A novel and effective process of thermal reduction treatment with the addition of metallic iron (Fe(0)) to recover lead from cathode ray tube (CRT) funnel glass is introduced. The key technological breakthrough of this process is the use of a relatively lower temperature and an inexpensive reducing agent to extract the metallic lead. The influences of temperature, the reducing agent content, and the holding time for lead reduction were examined to determine the optimal extraction efficiency. The lead extraction efficiency first increased and then decreased with increasing temperature. The maximum lead extraction efficiency occurred at 700 °C. The growth of crystalline lead first increased significantly with an increase in the Fe content, reaching maximum growth at an Fe addition of 50 wt %. The most effective treatment time was determined to be 30 min, as the vitrification of lead back to the glass matrix occurred under longer treatment times. The experimentally derived results indicate that a 58 wt % lead extraction can be achieved with the optimized operational parameters (50 wt % Fe addition, heating at 700 °C for 30 min) in a single extraction operation.

  10. Characterization of lead, barium and strontium leachability from foam glasses elaborated using waste cathode ray-tube glasses.

    PubMed

    Yot, Pascal G; Méar, François O

    2011-01-15

    Foam glass manufacture is a promising mode for re-using cathode ray tube (CRT) glasses. Nevertheless, because CRTs employ glasses containing heavy metals such as lead, barium and strontium, the leaching behaviour of foam glasses fabricated from CRTs must be understood. Using the AFNOR X 31-210 leaching assessment procedure, the degree of element inertization in foam glasses synthesized from waste CRT glasses (funnel and panel glasses, containing lead and barium/strontium respectively) were determined. The amount of leached lead from foam glasses prepared from funnel glass depends on the nature and concentration of the reducing agent. The effects of the reducing agents on the generation of cellular structure in the fabrication of foam glass were studied. The fraction of lead released from foam glass was less than those extracted from funnel glass and was lower than the statutory limit. Leached concentrations of barium and strontium were found to be approximately constant in various tests and were also below regulatory limits.

  11. Preparation of lead oxide nanoparticles from cathode-ray tube funnel glass by self-propagating method.

    PubMed

    Wang, Yu; Zhu, Jianxin

    2012-05-15

    This paper presents a novel process of extracting lead oxide nanoparticles from cathode-ray tube (CRT) funnel glass using self-propagating high-temperature synthesis (SHS) method. The impacts of added amount of funnel glass on the extraction ratio of lead, the lead extraction velocity and the micromorphology, as well as particle size of extracted nanoparticles were investigated. We found that self-propagating reaction in the presence of Mg and Fe(2)O(3) could separate lead preferentially and superfine lead oxide nanoparticles were obtained from a collecting chamber. The separation ratio was related closely to the amount of funnel glass added in the original mixture. At funnel glass addition of no more than 40wt.%, over 90wt.% of lead was recovered from funnel glass. High extraction yield reveals that the network structure of funnel glass was fractured due to the dramatic energy generated during the SHS melting process. The PbO nanoparticles collected show good dispersion and morphology with a mean grain size of 40-50nm.

  12. Energy-efficient modification of reduction-melting for lead recovery from cathode ray tube funnel glass.

    PubMed

    Okada, Takashi; Yonezawa, Susumu

    2013-08-01

    Lead can be recovered from funnel glass of waste cathode ray tubes via reduction melting. While low-temperature melting is necessary for reduced energy consumption, previously proposed methods required high melting temperatures (1400 °C) for the reduction melting. In this study, the reduction melting of the funnel glass was performed at 900-1000 °C using a lab-scale reactor with varying concentrations of Na(2)CO(3) at different melting temperatures and melting times. The optimum Na(2)CO(3) dosage and melting temperature for efficient lead recovery was 0.5 g per 1g of the funnel glass and 1000 °C respectively. By the reduction melting with the mentioned conditions, 92% of the lead in the funnel glass was recovered in 60 min. However, further lead recovery was difficult because the rate of the lead recovery decreased as with the recovery of increasing quantity of the lead from the glass. Thus, the lead remaining in the glass after the reduction melting was extracted with 1M HCl, and the lead recovery improved to 98%.

  13. The effect of cathode ray tube display format on observer performance in dental digitized radiography: comparison with plain films.

    PubMed

    Møystad, A; Svanaes, D B; Larheim, T A; Gröndahl, H G

    1994-11-01

    Studies of observer performance with non-manipulated digital images are almost lacking; nor has the effect of cathode ray tube (CRT) display formats been evaluated. The present study compared the diagnostic accuracy of observers with and without clinical experience in evaluating intra-oral dental films and the corresponding non-manipulated digitized images. Three different-sized (5", 9", 17") monitors were used to study the effect of CRT display format. Artificial radiolucent and radiopaque lesions in dry human mandibles were examined. ROC curve areas were averaged and cross-tabulated according to viewing method and observer experience. For the total group, the non-manipulated digital images resulted in smaller ROC curve areas than the plain films for all CRT formats, with a significantly inferior result for the 17" images (p = 0.036). The increase in diagnostic accuracy of the digital images with decreasing CRT size was not significant (p > 0.05). There was some difference in the mean ROC curve areas between teachers and students, but the effect of the viewing methods was not significant. In terms of observer performance, the experienced observers demonstrated a reduced, and the inexperienced an increased, variability with the digital images compared with conventional film.

  14. Theoretical calculation of product contents: battery and cathode ray tube examples.

    PubMed

    Thomas, Valerie M

    2003-05-01

    Most product environmental assessments are based on manufacturer-supplied data on the material content of the product. This paper explores the potential for the material content of key components to be estimated with theoretical calculations. Two examples, the amount of cadmium in a nickel-cadmium battery and the amount of lead in a TV or computer CRT monitor, are developed. Both an upper and a lower limit on the amount of cadmium in a nickel-cadmium battery are calculated on the basis of the battery's chemical reaction. The amount of lead shielding needed in a TV or CRT computer monitor is estimated on the basis of the potential difference through which electrons are accelerated and the absorption length of photons in lead. Such calculations can be used as benchmarks in product environmental assessments, providing validation of manufacturer-supplied data and providing insight into the composition and design of products.

  15. Characteristics of a multi-keV monochromatic point x-ray source based on vacuum diode with laser-produced plasma as cathode

    NASA Astrophysics Data System (ADS)

    Moorti, A.; Raghuramaiah, M.; Naik, P. A.; Gupta, P. D.

    2004-11-01

    Temporal, spatial and spectral characteristics of a multi-keV monochromatic point x-ray source based on vacuum diode with laser-produced plasma as cathode are presented. Electrons from a laser-produced aluminium plasma were accelerated towards a conical point tip titanium anode to generate K-shell x-ray radiation. Approximately 10^{10} photons/pulse were generated in x-ray pulses of sim18 to sim28 ns duration from a source of sim300 mum diameter, at hnu = 4.51 keV (K_{al} emission of titanium), with a brightness of sim10^{20} photons/cm^2/s/sr. This was sufficient to record single-shot x-ray radiographs of physical objects on a DEF-5 x-ray film kept at a distance of up to sim10 cm.

  16. A fast phase space method for computing creeping rays

    SciTech Connect

    Motamed, Mohammad . E-mail: mohamad@nada.kth.se; Runborg, Olof . E-mail: olofr@nada.kth.se

    2006-11-20

    Creeping rays can give an important contribution to the solution of medium to high frequency scattering problems. They are generated at the shadow lines of the illuminated scatterer by grazing incident rays and propagate along geodesics on the scatterer surface, continuously shedding diffracted rays in their tangential direction. In this paper, we show how the ray propagation problem can be formulated as a partial differential equation (PDE) in a three-dimensional phase space. To solve the PDE we use a fast marching method. The PDE solution contains information about all possible creeping rays. This information includes the phase and amplitude of the field, which are extracted by a fast post-processing. Computationally, the cost of solving the PDE is less than tracing all rays individually by solving a system of ordinary differential equations. We consider an application to mono-static radar cross section problems where creeping rays from all illumination angles must be computed. The numerical results of the fast phase space method and a comparison with the results of ray tracing are presented.

  17. X-ray fluorescence computed tomography system for biomedical imaging

    NASA Astrophysics Data System (ADS)

    Enomoto, Toshiyuki; Sato, Eiichi; Abderyim, Purkhet; Matsukiyo, Hiroshi; Osawa, Akihiro; Watanabe, Manabu; Nagao, Jiro; Nomiya, Seiichiro; Hitomi, Keitro; Izumisawa, Mitsuru; Ogawa, Akira; Sato, Shigehiro

    2008-08-01

    An x-ray fluorescence (XRF) computed tomography (CT) system utilizing a cadmium telluride (CdTe) detector is described. The CT system is of the first generation type and consists of a cerium x-ray generator, a turn table, a translation stage, a two-stage controller, a CdTe spectrometer, a multichannel analyzer (MCA), a counter board (CB), and a personal computer (PC). When an object is exposed by the x-ray generator, iodine K-series fluorescences are produced and are detected from vertical direction to x-ray axis using the spectrometer. Fluorescent photons are selected out using the MCA and are counted by the PC via CB, and XRF CT is performed by repeating translation and rotation of an object.

  18. A novel surface-sensitive X-ray absorption spectroscopic detector to study the thermal decomposition of cathode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Nonaka, Takamasa; Okuda, Chikaaki; Oka, Hideaki; Nishimura, Yusaku F.; Makimura, Yoshinari; Kondo, Yasuhito; Dohmae, Kazuhiko; Takeuchi, Yoji

    2016-09-01

    A surface-sensitive conversion-electron-yield X-ray absorption fine structure (CEY-XAFS) detector that operates at elevated temperatures is developed to investigate the thermal decomposition of cathode materials for Li-ion batteries. The detector enables measurements with the sample temperature controlled from room temperature up to 450 °C. The detector is applied to the LiNi0.75Co0.15Al0.05Mg0.05O2 cathode material at 0% state of charge (SOC) and 50% SOC to examine the chemical changes that occur during heating in the absence of an electrolyte. The combination of surface-sensitive CEY-XAFS and bulk-sensitive transmission-mode XAFS shows that the reduction of Ni and Co ions begins at the surface of the cathode particles at around 150 °C, and propagates inside the particle upon further heating. These changes with heating are irreversible and are more obvious at 50% SOC than at 0% SOC. The fraction of reduced Ni ions is larger than that of reduced Co ions. These results demonstrate the capability of the developed detector to obtain important information for the safe employment of this cathode material in Li-ion batteries.

  19. Magnification error of digital x rays on the computer screen.

    PubMed

    Ranjitkar, S; Prakash, D; Prakash, R

    2014-12-01

    Templating x-rays of total hip and knee replacements pre-operatively are important to plan surgery. This is usually done using acetate templates of the prosthesis on hard copies of the x-ray. With the change in practice, to use digital x-rays on computer screens instead of hard copies, it is important to assess if acetate templates can be used for digital x-rays on the computer screen. This is a retrospective x-ray study of 19 hip replacements and 30 knee replacements to assess their magnification using the Patient Archiving Computerised System (PACS) software. This study was done to assess the accuracy of magnification, using acetate templates over a computer screen. In total hip replacement, the outer cup diameter was also measured using the digital measurement scale. The mean magnification was 0.59 for the acetabular cup and the femoral stem in total hip replacement and 0.48 for the femoral and tibial implant in total knee replacement. The mean difference in cup diameter comparing to the real size was an excess of 10.21 mm. The study showed over-magnified hip and knee x-rays thus suggesting that acetate templates and measurement scales on PACS was not reliable.

  20. Cathodic protection for nuclear waste packaging under gamma ray irradiation by using TiO{sub 2} coating combined with glass scintillators

    SciTech Connect

    Fujisawa, Ryutaro; Tsujikawa, Shigeo

    1995-12-31

    The photoelectrochemical behaviors of a TiO{sub 2} single crystal and TiO{sub 2} coating were studied, for the purposes of cathodic protection of stainless steels and Cu via the TiO{sub 2} coating combined with glass scintillators under gamma ray irradiation. It was confirmed that a TiO{sub 2} coating could protect 304 stainless steel cathodically from crevice corrosion under illumination. A logarithmic relationship between the photopotential of single crystal TiO{sub 2} (rutile) and light intensity was found, moreover, the photopotential was found to be least noble when wavelength equals 375 nm. Under illumination by gamma rays combined with the glass scintillators, the electrode potential of single crystal TiO{sub 2} was found to shift in the less noble direction by about 200 mV. Therefore, the technique of cathodic protection by TiO{sub 2} coating is considered to be applicable to protect the packaging metal from corrosion for a long time.

  1. Material/element-dependent fluorescence-yield modes on soft X-ray absorption spectroscopy of cathode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Asakura, Daisuke; Hosono, Eiji; Nanba, Yusuke; Zhou, Haoshen; Okabayashi, Jun; Ban, Chunmei; Glans, Per-Anders; Guo, Jinghua; Mizokawa, Takashi; Chen, Gang; Achkar, Andrew J.; Hawthron, David G.; Regier, Thomas Z.; Wadati, Hiroki

    2016-03-01

    We evaluate the utilities of fluorescence-yield (FY) modes in soft X-ray absorption spectroscopy (XAS) of several cathode materials for Li-ion batteries. In the case of total-FY (TFY) XAS for LiNi0.5Mn1.5O4, the line shape of the Mn L3-edge XAS was largely distorted by the self-absorption and saturation effects, while the distortions were less pronounced at the Ni L3 edge. The distortions were suppressed for the inverse-partial-FY (IPFY) spectra. We found that, in the cathode materials, the IPFY XAS is highly effective for the Cr, Mn, and Fe L edges and the TFY and PFY modes are useful enough for the Ni L edge which is far from the O K edge.

  2. X-ray Crystallographic Computations Using a Programmable Calculator.

    ERIC Educational Resources Information Center

    Attard, Alfred E.; Lee, Henry C.

    1979-01-01

    Describes six crystallographic programs which have been developed to illustrate the range of usefulness of programmable calculators in providing computational assistance in chemical analysis. These programs are suitable for the analysis of x-ray diffraction data in the laboratory by students. (HM)

  3. [X-ray computed tomography in the diagnosis of mediastinitis].

    PubMed

    Abakumov, M M; Barmina, T G; Ishmukhametov, A I

    2001-01-01

    Results of X-ray computed tomography (RCT) use in 21 patients treated for acute mediastinitis in N.V. Sklifosovsky Emergency Care Research Institute have been analyzed retrospectively. RCT proved able to defect accurate location, spreading and sizes of inflammatory disorders in the mediastinum are demonstrated. Semiotics of mediastinitis depending on location, spreading and phase of inflammatory process is presented.

  4. 21 CFR 892.1750 - Computed tomography x-ray system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Computed tomography x-ray system. 892.1750 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1750 Computed tomography x-ray system. (a) Identification. A computed tomography x-ray system is a diagnostic x-ray system intended...

  5. 21 CFR 892.1750 - Computed tomography x-ray system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Computed tomography x-ray system. 892.1750 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1750 Computed tomography x-ray system. (a) Identification. A computed tomography x-ray system is a diagnostic x-ray system intended...

  6. 21 CFR 892.1750 - Computed tomography x-ray system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Computed tomography x-ray system. 892.1750 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1750 Computed tomography x-ray system. (a) Identification. A computed tomography x-ray system is a diagnostic x-ray system intended...

  7. 21 CFR 892.1750 - Computed tomography x-ray system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Computed tomography x-ray system. 892.1750 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1750 Computed tomography x-ray system. (a) Identification. A computed tomography x-ray system is a diagnostic x-ray system intended...

  8. 21 CFR 892.1750 - Computed tomography x-ray system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Computed tomography x-ray system. 892.1750 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1750 Computed tomography x-ray system. (a) Identification. A computed tomography x-ray system is a diagnostic x-ray system intended...

  9. Multiple pinhole collimator based X-ray luminescence computed tomography.

    PubMed

    Zhang, Wei; Zhu, Dianwen; Lun, Michael; Li, Changqing

    2016-07-01

    X-ray luminescence computed tomography (XLCT) is an emerging hybrid imaging modality, which is able to improve the spatial resolution of optical imaging to hundreds of micrometers for deep targets by using superfine X-ray pencil beams. However, due to the low X-ray photon utilization efficiency in a single pinhole collimator based XLCT, it takes a long time to acquire measurement data. Herein, we propose a multiple pinhole collimator based XLCT, in which multiple X-ray beams are generated to scan a sample at multiple positions simultaneously. Compared with the single pinhole based XLCT, the multiple X-ray beam scanning method requires much less measurement time. Numerical simulations and phantom experiments have been performed to demonstrate the feasibility of the multiple X-ray beam scanning method. In one numerical simulation, we used four X-ray beams to scan a cylindrical object with 6 deeply embedded targets. With measurements from 6 angular projections, all 6 targets have been reconstructed successfully. In the phantom experiment, we generated two X-ray pencil beams with a collimator manufactured in-house. Two capillary targets with 0.6 mm edge-to-edge distance embedded in a cylindrical phantom have been reconstructed successfully. With the two beam scanning, we reduced the data acquisition time by 50%. From the reconstructed XLCT images, we found that the Dice similarity of targets is 85.11% and the distance error between two targets is less than 3%. We have measured the radiation dose during XLCT scan and found that the radiation dose, 1.475 mSv, is in the range of a typical CT scan. We have measured the changes of the collimated X-ray beam size and intensity at different distances from the collimator. We have also studied the effects of beam size and intensity in the reconstruction of XLCT.

  10. Multiple pinhole collimator based X-ray luminescence computed tomography.

    PubMed

    Zhang, Wei; Zhu, Dianwen; Lun, Michael; Li, Changqing

    2016-07-01

    X-ray luminescence computed tomography (XLCT) is an emerging hybrid imaging modality, which is able to improve the spatial resolution of optical imaging to hundreds of micrometers for deep targets by using superfine X-ray pencil beams. However, due to the low X-ray photon utilization efficiency in a single pinhole collimator based XLCT, it takes a long time to acquire measurement data. Herein, we propose a multiple pinhole collimator based XLCT, in which multiple X-ray beams are generated to scan a sample at multiple positions simultaneously. Compared with the single pinhole based XLCT, the multiple X-ray beam scanning method requires much less measurement time. Numerical simulations and phantom experiments have been performed to demonstrate the feasibility of the multiple X-ray beam scanning method. In one numerical simulation, we used four X-ray beams to scan a cylindrical object with 6 deeply embedded targets. With measurements from 6 angular projections, all 6 targets have been reconstructed successfully. In the phantom experiment, we generated two X-ray pencil beams with a collimator manufactured in-house. Two capillary targets with 0.6 mm edge-to-edge distance embedded in a cylindrical phantom have been reconstructed successfully. With the two beam scanning, we reduced the data acquisition time by 50%. From the reconstructed XLCT images, we found that the Dice similarity of targets is 85.11% and the distance error between two targets is less than 3%. We have measured the radiation dose during XLCT scan and found that the radiation dose, 1.475 mSv, is in the range of a typical CT scan. We have measured the changes of the collimated X-ray beam size and intensity at different distances from the collimator. We have also studied the effects of beam size and intensity in the reconstruction of XLCT. PMID:27446686

  11. Multiple pinhole collimator based X-ray luminescence computed tomography

    PubMed Central

    Zhang, Wei; Zhu, Dianwen; Lun, Michael; Li, Changqing

    2016-01-01

    X-ray luminescence computed tomography (XLCT) is an emerging hybrid imaging modality, which is able to improve the spatial resolution of optical imaging to hundreds of micrometers for deep targets by using superfine X-ray pencil beams. However, due to the low X-ray photon utilization efficiency in a single pinhole collimator based XLCT, it takes a long time to acquire measurement data. Herein, we propose a multiple pinhole collimator based XLCT, in which multiple X-ray beams are generated to scan a sample at multiple positions simultaneously. Compared with the single pinhole based XLCT, the multiple X-ray beam scanning method requires much less measurement time. Numerical simulations and phantom experiments have been performed to demonstrate the feasibility of the multiple X-ray beam scanning method. In one numerical simulation, we used four X-ray beams to scan a cylindrical object with 6 deeply embedded targets. With measurements from 6 angular projections, all 6 targets have been reconstructed successfully. In the phantom experiment, we generated two X-ray pencil beams with a collimator manufactured in-house. Two capillary targets with 0.6 mm edge-to-edge distance embedded in a cylindrical phantom have been reconstructed successfully. With the two beam scanning, we reduced the data acquisition time by 50%. From the reconstructed XLCT images, we found that the Dice similarity of targets is 85.11% and the distance error between two targets is less than 3%. We have measured the radiation dose during XLCT scan and found that the radiation dose, 1.475 mSv, is in the range of a typical CT scan. We have measured the changes of the collimated X-ray beam size and intensity at different distances from the collimator. We have also studied the effects of beam size and intensity in the reconstruction of XLCT. PMID:27446686

  12. Updated Computational Model of Cosmic Rays Near Earth

    NASA Technical Reports Server (NTRS)

    ONeill, Patrick M.

    2006-01-01

    An updated computational model of the galactic-cosmic-ray (GCR) environment in the vicinity of the Earth, Earth s Moon, and Mars has been developed, and updated software has been developed to implement the updated model. This model accounts for solar modulation of the cosmic-ray contribution for each element from hydrogen through iron by computationally propagating the local interplanetary spectrum of each element through the heliosphere. The propagation is effected by solving the Fokker-Planck diffusion, convection, energy-loss boundary-value problem. The Advanced Composition Explorer NASA satellite has provided new data on GCR energy spectra. These new data were used to update the original model and greatly improve the accuracy of prediction of interplanetary GCR.

  13. Data fusion in neutron and X-ray computed tomography

    SciTech Connect

    Schrapp, Michael J.; Goldammer, Matthias; Schulz, Michael; Issani, Siraj; Bhamidipati, Suryanarayana; Böni, Peter

    2014-10-28

    We present a fusion methodology between neutron and X-ray computed tomography (CT). On the one hand, the inspection by X-ray CT of a wide class of multimaterials in non-destructive testing applications suffers from limited information of object features. On the other hand, neutron imaging can provide complementary data in such a way that the combination of both data sets fully characterizes the object. In this contribution, a novel data fusion procedure, called Fusion Regularized Simultaneous Algebraic Reconstruction Technique, is developed where the X-ray reconstruction is modified to fulfill the available data from the imaging with neutrons. The experiments, which were obtained from an aluminum profile containing a steel screw, and attached carbon fiber plates demonstrate that the image quality in CT can be significantly improved when the proposed fusion method is used.

  14. X-Ray Computed Tomography Monitors Damage in Composites

    NASA Technical Reports Server (NTRS)

    Baaklini, George Y.

    1997-01-01

    The NASA Lewis Research Center recently codeveloped a state-of-the-art x-ray CT facility (designated SMS SMARTSCAN model 100-112 CITA by Scientific Measurement Systems, Inc., Austin, Texas). This multipurpose, modularized, digital x-ray facility includes an imaging system for digital radiography, CT, and computed laminography. The system consists of a 160-kV microfocus x-ray source, a solid-state charge-coupled device (CCD) area detector, a five-axis object-positioning subassembly, and a Sun SPARCstation-based computer system that controls data acquisition and image processing. The x-ray source provides a beam spot size down to 3 microns. The area detector system consists of a 50- by 50- by 3-mm-thick terbium-doped glass fiber-optic scintillation screen, a right-angle mirror, and a scientific-grade, digital CCD camera with a resolution of 1000 by 1018 pixels and 10-bit digitization at ambient cooling. The digital output is recorded with a high-speed, 16-bit frame grabber that allows data to be binned. The detector can be configured to provide a small field-of-view, approximately 45 by 45 mm in cross section, or a larger field-of-view, approximately 60 by 60 mm in cross section. Whenever the highest spatial resolution is desired, the small field-of-view is used, and for larger samples with some reduction in spatial resolution, the larger field-of-view is used.

  15. Dual-Cathode Electron-Beam Source

    NASA Technical Reports Server (NTRS)

    Bradley, James G.; Conley, Joseph M.; Wittry, David B.

    1988-01-01

    Beam from either cathode electromagnetically aligned with exit port. Electron beam from either of two cathodes deflected by magnetic and electric fields to central axis. Mechanical alignment of beam easy because cathode axes, anode apertures, and electron trajectories coplanar. Applications where uninterrupted service needed: scanning electron microscopes, transmission electron microscopes, electron-beam lithography equipment, Auger instruments, and microfocused x-ray sources.

  16. High-resolution X-ray projection radiography of a pin cathode in a high-current vacuum diode using X-pinch radiation

    NASA Astrophysics Data System (ADS)

    Parkevich, E. V.; Tilikin, I. N.; Agafonov, A. V.; Shelkovenko, T. A.; Romanova, V. M.; Mingaleev, A. R.; Savinov, S. Yu.; Mesyats, G. A.; Pikuz, S. A.

    2016-03-01

    To study processes in a high-current vacuum diode with a cathode in the form of a single pin made of a metallic wire 20-30 μm in diameter, the method of high-resolution projection X-ray radiography with an X-pinch as a source has been used. A strong inhomogeneity of the energy contribution to the wire has been revealed. The smallest energy release has been observed near the end of the pin, where the electric field strength is maximal. Hard X rays, as well as the ejection of matter from the anode, have been observed, indicating the generation of an electron beam with the parameters characteristic of explosive electron emission in the diode with this configuration. The data obtained indicate complex processes occurring in the diode. Possible scenarios of their development have been considered.

  17. On the features of bursts of neutrons, hard x-rays and alpha-particles in the pulse vacuum discharge with a virtual cathode and self-organization

    NASA Astrophysics Data System (ADS)

    Kurilenkov, Yu K.; Tarakanov, V. P.; Gus'kov, S. Yu; Samoylov, I. S.; Ostashev, V. E.

    2015-11-01

    In this paper, we continue the discussion of the experimental results on the yield of DD neutrons and hard x-rays in the nanosecond vacuum discharge (NVD) with a virtual cathode, which was started in the previous article of this issue, and previously (Kurilenkov Y K et al 2006 J. Phys. A: Math. Gen. 39 4375). We have considered here the regimes of very dense interelectrode aerosol ensembles, in which diffusion of even hard x-rays is found. The yield of DD neutrons in these regimes is conditioned not only by the head-on deuteron-deuteron collisions in the potential well of virtual cathode, but also by the channel of “deuteron-deuterium cluster” reaction, which exceeds overall yield of neutrons per a shot by more than an order of magnitude, bringing it up to ∼ 107/(4π). Very bright bursts of hard x-rays are also represented and discussed here. Presumably, their nature may be associated with the appearance in the NVD of some properties of random laser in the x-ray spectrum. Good preceding agreeing of the experiment on the DD fusion in the NVD with its particle-in-cell (PIC) simulations provides a basis to begin consideration of nuclear burning “proton-boron” in the NVD, which will be accompanied by the release of alpha particles only. With this objective in view, there has been started the PIC-simulation of aneutronic burning of p-B11, and its preliminary results are presented.

  18. A General Computer Program for Ionospheric Ray-Tracing

    NASA Technical Reports Server (NTRS)

    Gonzales, Victor H.

    1961-01-01

    The study of the ionosphere using the Faraday rotation effect has been undertaken recently by means of rocket, satellite, and moon echo experiments. Different approximations have been used by different authors, resulting in methods with different degrees of complexity, and it is possible to say that the more accurate a method is, the more difficult its application becomes. However, the use of modern high-speed digital computers offers the possibility of using more complex methods in the solution of this problem, The program described in this report was written for the ILLIAC, the digital computer of the University of Illinois. Only the general features common to most digital computers will be mentioned. This program was prepared having in mind the analysis of the Faraday rotation effect, as recorded from artificial satellites. It is intended to be as general as possible in the conditions imposed on the assumed propagating medium: specifically there are no restrictions on the models of the electron density distribution and the earth's magnetic fields. long as the ray theory Ls valid. The program will trace separately the ordinary and the extraordinary mode, and it will find the virtual phase path length of a ray of each mode between the transmitter (satellite) and a receiver (station). The difference between respective phase path-lengths is related to the Faraday rotation through a constant which depends on the frequency.

  19. Wolter X-Ray Microscope Computed Tomography Ray-Trace Model with Preliminary Simulation Results

    SciTech Connect

    Jackson, J A

    2006-02-27

    It is proposed to build a Wolter X-ray Microscope Computed Tomography System in order to characterize objects to sub-micrometer resolution. Wolter Optics Systems use hyperbolic, elliptical, and/or parabolic mirrors to reflect x-rays in order to focus or magnify an image. Wolter Optics have been used as telescopes and as microscopes. As microscopes they have been used for a number of purposes such as measuring emission x-rays and x-ray fluoresce of thin biological samples. Standard Computed Tomography (CT) Systems use 2D radiographic images, from a series of rotational angles, acquired by passing x-rays through an object to reconstruct a 3D image of the object. The x-ray paths in a Wolter X-ray Microscope will be considerably different than those of a standard CT system. There is little information about the 2D radiographic images that can be expected from such a system. There are questions about the quality, resolution and focusing range of an image created with such a system. It is not known whether characterization information can be obtained from these images and whether these 2D images can be reconstructed to 3D images of the object. A code has been developed to model the 2D radiographic image created by an object in a Wolter X-ray Microscope. This code simply follows the x-ray through the object and optics. There is no modeling at this point of other effects, such as scattering, reflection losses etc. Any object, of appropriate size, can be used in the model code. A series of simulations using a number of different objects was run to study the effects of the optics. The next step will be to use this model to reconstruct an object from the simulated data. Funding for the project ended before this goal could be accomplished. The following documentation includes: (1) background information on current X-ray imaging systems, (2) background on Wolter Optics, (3) description of the Wolter System being used, (4) purpose, limitations and development of the modeling

  20. X-ray energy optimisation in computed microtomography.

    PubMed

    Spanne, P

    1989-06-01

    Expressions describing the absorbed dose and the number of incident photons necessary for the detection of a contrasting detail in x-ray transmission CT imaging of a circular phantom are derived as functions of the linear attenuation coefficients of the materials comprising the object and the detail. A shell of a different material can be included to allow simulation of CT imaging of the skulls of small laboratory animals. The equations are used to estimate the optimum photon energy in x-ray transmission computed microtomography. The optimum energy depends on whether the number of incident photons or the absorbed dose at a point in the object is minimised. For a water object of 300 mm diameter the two optimisation criteria yield optimum photon energies differing by an order of magnitude.

  1. Bronnikov-aided correction for x-ray computed tomography.

    PubMed

    De Witte, Yoni; Boone, Matthieu; Vlassenbroeck, Jelle; Dierick, Manuel; Van Hoorebeke, Luc

    2009-04-01

    When a very-low-absorbing sample is scanned at an x-ray computed tomography setup with a microfocus x-ray tube and a high-resolution detector, the obtained projection images contain not only absorption contrast but also phase contrast. While images without a phase signal can be reconstructed very well, such mixed phase and absorption images give rise to severe artifacts in the reconstructed slices. A method is described that applies a correction to these mixed projections to remove the phase signal. These corrected images can then be processed using a standard filtered backprojection algorithm to obtain reconstructions with only few or no phase artifacts. This new method, which we call the Bronnikov-aided correction (BAC), can be used in a broad variety of applications and without much additional effort. It is tested on a biological and a pharmaceutical sample, and results are evaluated and discussed by comparing them with those of conventional reconstruction methods. PMID:19340263

  2. Quantitative cone beam X-ray luminescence tomography/X-ray computed tomography imaging

    SciTech Connect

    Chen, Dongmei; Zhu, Shouping Chen, Xueli; Chao, Tiantian; Cao, Xu; Zhao, Fengjun; Huang, Liyu; Liang, Jimin

    2014-11-10

    X-ray luminescence tomography (XLT) is an imaging technology based on X-ray-excitable materials. The main purpose of this paper is to obtain quantitative luminescence concentration using the structural information of the X-ray computed tomography (XCT) in the hybrid cone beam XLT/XCT system. A multi-wavelength luminescence cone beam XLT method with the structural a priori information is presented to relieve the severe ill-posedness problem in the cone beam XLT. The nanophosphors and phantom experiments were undertaken to access the linear relationship of the system response. Then, an in vivo mouse experiment was conducted. The in vivo experimental results show that the recovered concentration error as low as 6.67% with the location error of 0.85 mm can be achieved. The results demonstrate that the proposed method can accurately recover the nanophosphor inclusion and realize the quantitative imaging.

  3. A portable x-ray source with a nanostructured Pt-coated silicon field emission cathode for absorption imaging of low-Z materials

    NASA Astrophysics Data System (ADS)

    Basu, Anirban; Swanwick, Michael E.; Fomani, Arash A.; Velásquez-García, Luis Fernando

    2015-06-01

    We report the design, fabrication, and characterization of a portable x-ray generator for imaging of low-atomic number materials such as biological soft tissue. The system uses a self-aligned, gated, Pt-coated silicon field emitter cathode with two arrays of 62 500 nano-sharp tips arranged in a square grid with 10 μm emitter pitch, and a natural convection-cooled reflection anode composed of a Cu bar coated with a thin Mo film. Characterization of the field emitter array demonstrated continuous emission of 1 mA electron current (16 mA cm  -  2) with  >95% current transmission at a 150 V gate-emitter bias voltage for over 20 h with no degradation. The emission of the x-ray source was characterized across a range of anode bias voltages to maximize the fraction of photons from the characteristic K-shell peaks of the Mo film to produce a quasi-monochromatic photon beam, which enables capturing high-contrast images of low-atomic number materials. The x-ray source operating at the optimum anode bias voltage, i.e. 35 kV, was used to image ex vivo and nonorganic samples in x-ray fluoroscopic mode while varying the tube current; the images resolve feature sizes as small as ~160 µm.

  4. Failure analysis of fuel cell electrodes using three-dimensional multi-length scale X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Pokhrel, A.; El Hannach, M.; Orfino, F. P.; Dutta, M.; Kjeang, E.

    2016-10-01

    X-ray computed tomography (XCT), a non-destructive technique, is proposed for three-dimensional, multi-length scale characterization of complex failure modes in fuel cell electrodes. Comparative tomography data sets are acquired for a conditioned beginning of life (BOL) and a degraded end of life (EOL) membrane electrode assembly subjected to cathode degradation by voltage cycling. Micro length scale analysis shows a five-fold increase in crack size and 57% thickness reduction in the EOL cathode catalyst layer, indicating widespread action of carbon corrosion. Complementary nano length scale analysis shows a significant reduction in porosity, increased pore size, and dramatically reduced effective diffusivity within the remaining porous structure of the catalyst layer at EOL. Collapsing of the structure is evident from the combination of thinning and reduced porosity, as uniquely determined by the multi-length scale approach. Additionally, a novel image processing based technique developed for nano scale segregation of pore, ionomer, and Pt/C dominated voxels shows an increase in ionomer volume fraction, Pt/C agglomerates, and severe carbon corrosion at the catalyst layer/membrane interface at EOL. In summary, XCT based multi-length scale analysis enables detailed information needed for comprehensive understanding of the complex failure modes observed in fuel cell electrodes.

  5. X-ray computed tomography using curvelet sparse regularization

    SciTech Connect

    Wieczorek, Matthias Vogel, Jakob; Lasser, Tobias; Frikel, Jürgen; Demaret, Laurent; Eggl, Elena; Pfeiffer, Franz; Kopp, Felix; Noël, Peter B.

    2015-04-15

    Purpose: Reconstruction of x-ray computed tomography (CT) data remains a mathematically challenging problem in medical imaging. Complementing the standard analytical reconstruction methods, sparse regularization is growing in importance, as it allows inclusion of prior knowledge. The paper presents a method for sparse regularization based on the curvelet frame for the application to iterative reconstruction in x-ray computed tomography. Methods: In this work, the authors present an iterative reconstruction approach based on the alternating direction method of multipliers using curvelet sparse regularization. Results: Evaluation of the method is performed on a specifically crafted numerical phantom dataset to highlight the method’s strengths. Additional evaluation is performed on two real datasets from commercial scanners with different noise characteristics, a clinical bone sample acquired in a micro-CT and a human abdomen scanned in a diagnostic CT. The results clearly illustrate that curvelet sparse regularization has characteristic strengths. In particular, it improves the restoration and resolution of highly directional, high contrast features with smooth contrast variations. The authors also compare this approach to the popular technique of total variation and to traditional filtered backprojection. Conclusions: The authors conclude that curvelet sparse regularization is able to improve reconstruction quality by reducing noise while preserving highly directional features.

  6. Multi-Mounted X-Ray Computed Tomography.

    PubMed

    Fu, Jian; Liu, Zhenzhong; Wang, Jingzheng

    2016-01-01

    Most existing X-ray computed tomography (CT) techniques work in single-mounted mode and need to scan the inspected objects one by one. It is time-consuming and not acceptable for the inspection in a large scale. In this paper, we report a multi-mounted CT method and its first engineering implementation. It consists of a multi-mounted scanning geometry and the corresponding algebraic iterative reconstruction algorithm. This approach permits the CT rotation scanning of multiple objects simultaneously without the increase of penetration thickness and the signal crosstalk. Compared with the conventional single-mounted methods, it has the potential to improve the imaging efficiency and suppress the artifacts from the beam hardening and the scatter. This work comprises a numerical study of the method and its experimental verification using a dataset measured with a developed multi-mounted X-ray CT prototype system. We believe that this technique is of particular interest for pushing the engineering applications of X-ray CT. PMID:27073911

  7. Multi-Mounted X-Ray Computed Tomography

    PubMed Central

    Fu, Jian; Liu, Zhenzhong; Wang, Jingzheng

    2016-01-01

    Most existing X-ray computed tomography (CT) techniques work in single-mounted mode and need to scan the inspected objects one by one. It is time-consuming and not acceptable for the inspection in a large scale. In this paper, we report a multi-mounted CT method and its first engineering implementation. It consists of a multi-mounted scanning geometry and the corresponding algebraic iterative reconstruction algorithm. This approach permits the CT rotation scanning of multiple objects simultaneously without the increase of penetration thickness and the signal crosstalk. Compared with the conventional single-mounted methods, it has the potential to improve the imaging efficiency and suppress the artifacts from the beam hardening and the scatter. This work comprises a numerical study of the method and its experimental verification using a dataset measured with a developed multi-mounted X-ray CT prototype system. We believe that this technique is of particular interest for pushing the engineering applications of X-ray CT. PMID:27073911

  8. Cathodic arcs

    SciTech Connect

    Anders, Andre

    2003-10-29

    Cathodic arc plasma deposition has become the technology of choice for hard, wear and corrosion resistant coatings for a variety of applications. The history, basic physics of cathodic arc operation, the infamous macroparticle problem and common filter solutions, and emerging high-tech applications are briefly reviewed. Cathodic arc plasmas standout due to their high degree of ionization, with important consequences for film nucleation, growth, and efficient utilization of substrate bias. Industrial processes often use cathodic arc plasma in reactive mode. In contrast, the science of arcs has focused on the case of vacuum arcs. Future research directions include closing the knowledge gap for reactive mode, large area coating, linear sources and filters, metal plasma immersion process, with application in high-tech and biomedical fields.

  9. (sup 6)Li and (sup 7)MAS NMR and In Situ X-Ray Diffraction Studies of Lithium Manganate Cathode Materials

    SciTech Connect

    Lee, Young Joo; Wang, Francis; Grey, Clare P.; Mukerjee, Sanjeev; McBreen, James

    1998-11-30

    {sup 6}Li MAS NMR spectra of lithium manganese oxides with differing manganese oxidation states (LiMn{sub 2}O{sub 4}, Li{sub 4}Mn{sub 5}O{sub 12}, Li{sub 2}Mn{sub 4}O{sub 9}, and Li{sub 2}Mn{sub 2}O{sub 4}) are presented. Improved understanding of the lithium NMR spectra of these model compounds is used to interpret the local structure of the Li{sub x}Mn{sub 2}O{sub 4} cathode materials following electrochemical Li{sup +} deintercalation to various charging levels. In situ x-ray diffraction patterns of the same material during charging are also reported for comparison. Evidence for two-phase behavior for x <0.4 (Li{sub x}Mn{sub 2}O{sub 4}) is seen by both NMR and diffraction.

  10. Visualization of x-ray computer tomography using computer-generated holography

    NASA Astrophysics Data System (ADS)

    Daibo, Masahiro; Tayama, Norio

    1998-09-01

    The theory converted from x-ray projection data to the hologram directly by combining the computer tomography (CT) with the computer generated hologram (CGH), is proposed. The purpose of this study is to offer the theory for realizing the all- electronic and high-speed seeing through 3D visualization system, which is for the application to medical diagnosis and non- destructive testing. First, the CT is expressed using the pseudo- inverse matrix which is obtained by the singular value decomposition. CGH is expressed in the matrix style. Next, `projection to hologram conversion' (PTHC) matrix is calculated by the multiplication of phase matrix of CGH with pseudo-inverse matrix of the CT. Finally, the projection vector is converted to the hologram vector directly, by multiplication of the PTHC matrix with the projection vector. Incorporating holographic analog computation into CT reconstruction, it becomes possible that the calculation amount is drastically reduced. We demonstrate the CT cross section which is reconstituted by He-Ne laser in the 3D space from the real x-ray projection data acquired by x-ray television equipment, using our direct conversion technique.

  11. X- and {gamma}-ray computed tomography applications at LLNL

    SciTech Connect

    Roberson, G.P.; Martz, H.E.; Schneberk, D.J.; Azevedo, S.G.

    1993-04-01

    Members of the Nondestructive Evaluation (NDE) Section at the Lawrence Livermore National Laboratory (LLNL) have implemented the advanced three-dimensional imaging technique of x and {gamma}-ray computed tomography (CAT or CT) for industrial and scientific nondestructive evaluation. This technique provides internal and external views of materials, components, and assemblies nonintrusively. Our research and development includes building CT scanners as well as data preprocessing, image reconstruction, display and analysis algorithms. These capabilities have been applied for a variety of industrial and scientific NDE applications where objects can range in size from 1 mm{sup 3} to 1 m{sup 3}. Here we discuss the usefulness of Cr to evaluate: Ballistic target materials, high-explosives shape charges, missile nosetips, and reactor-fuel tubes.

  12. TU-A-9A-07: X-Ray Acoustic Computed Tomography (XACT): 100% Sensitivity to X-Ray Absorption

    SciTech Connect

    Xiang, L; Ahmad, M; Nikoozadeh, A; Pratx, G; Khuri-Yakub, B; Xing, L

    2014-06-15

    Purpose: To assess whether X-ray acoustic computed tomography (XACT) is more sensitive to X-ray absorption than that of the conventional X-ray imaging. Methods: First, a theoretical model was built to analyze the X-ray absorption sensitivity of XACT imaging and conventional X-ray imaging. Second, an XACT imaging system was developed to evaluate the X-ray induced acoustic signal generation as well as the sensitivity improvement over transmission x-ray imaging. Ultra-short x-ray pulses (60-nanosecond) were generated from an X-ray source operated at the energy of 150 kVp with a 10-Hz repetition rate. The X-ray pulse was synchronized with the acoustic detection via a x-ray scintillation triggering to acquire the X-ray induced acoustic signal. Results: Theoretical analysis shows that X-ray induced acoustic signal is sensitive only to the X-ray absorption, while completely insensitive to out the X-ray scattering and fluorescence. XACT has reduced background and increased contrast-to-noise ratio, and therefore has increased sensitivity compared to transmission x-ray imaging. For a 50-μm size, gadolinium insertion in tissue exposed to 40 keV X-rays; the sensitivity of XACT imaging is about 28.9 times higher than that of conventional X-ray imaging. Conclusion: X-ray acoustic computer tomography (XACT) as a new imaging modality combines X-ray absorption contrast and high ultrasonic resolution in a single modality. It is feasible to improve the imaging sensitivity with XACT imaging compared with conventional X-ray imaging. Taking advantage of the high ultrasonic resolution, it is possible to perform 3-D imaging with a single x-ray pulse with arrays of transducers without any mechanical motion of the imaging system. This single-shot capability offers the potential of reducing radiation dose by a factor of 1000, and imaging 100 times faster when compared to the conventional X-ray CT, and thus revolutionizing x-ray imaging applications in medicine and biology. The authors

  13. Monolithic cathodes

    NASA Astrophysics Data System (ADS)

    Davis, P. R.; Swanson, L. W.

    1985-11-01

    The purpose of this program was to evaluate LaB6 (210) and (310) oriented single crystal material for flat cathode applications and to deliver mounted LaB6 cathodes with (310) orientation for operation in RADC/Varian life test vehicles. To that end, the program was divided into four separate tasks, as shown in the report. This project was extended for 3 months past the initial program period so that unavoidable delays could be overcome and the project completed. The final report covers the entire period of the program, which terminated 29 March 1985.

  14. Combined Experimental and Computational Studies of a Na2 Ni1-x Cux Fe(CN)6 Cathode with Tunable Potential for Aqueous Rechargeable Sodium-Ion Batteries.

    PubMed

    Hung, Tai-Feng; Chou, Hung-Lung; Yeh, Yu-Wen; Chang, Wen-Sheng; Yang, Chang-Chung

    2015-10-26

    Herein, potential-tunable Na2 Ni1-x Cux Fe(CN)6 nanoparticles with three-dimensional frameworks and large interstitial spaces were synthesized as alternative cathode materials for aqueous sodium-ion batteries by controlling the molar ratio of Ni(II) to Cu(II) at ambient temperature. The influence of the value of x on the crystalline structure, lattice parameters, electrochemical properties, and charge transfer of the resultant compound was explored by using powder X-ray diffractometry, density functional theory, cyclic voltammetry, galvanostatic charge-discharge techniques, and Bader charge analysis. Of the various formulations investigated, that with x=0.25 delivered the highest reversible capacity, superior rate capability, and outstanding cycling performance. These attributes are ascribed to its unique face-centered cubic structure for facile sodium-ion insertion/extraction and the strong interactions between Cu and N atoms, which promote structural stability.

  15. X-ray Computed Tomography Observation of Methane Hydrate Dissociation

    USGS Publications Warehouse

    Tomutsa, L.; Freifeld, B.; Kneafsey, T.J.; Stern, L.A.

    2002-01-01

    Deposits of naturally occurring methane hydrate have been identified in permafrost and deep oceanic environments with global reserves estimated to be twice the total amount of energy stored in fossil fuels. The fundamental behavior of methane hydrate in natural formations, while poorly understood, is of critical importance if the economic recovery of methane from hydrates is to be accomplished. In this study, computed X-ray tomography (CT) scanning is used to image an advancing dissociation front in a heterogeneous gas hydrate/sand sample at 0.1 MPa. The cylindrical methane hydrate and sand aggregate, 2.54 cm in diameter and 6.3 cm long, was contained in a PVC sample holder that was insulated on all but one end. At the uninsulated end, the dissociated gas was captured and the volume of gas monitored. The sample was initially imaged axially using X-ray CT scanning within the methane hydrate stability zone by keeping the sample temperature at 77??K. Subsequently, as the sample warmed through the methane hydrate dissociation point at 194??K and room pressure, gas was produced and the temperature at the bottom of the sample plug was monitored while CT images were acquired. The experiment showed that CT imaging can resolve the reduction in density (as seen by a reduction in beam attenuation) of the hydrate/sand aggregate due to the dissociation of methane hydrate. In addition, a comparison of CT images with gas flow and temperature measurements reveals that the CT scanner is able to resolve accurately and spatially the advancing dissociation front. Future experiments designed to better understand the thermodynamics of hydrate dissociation are planned to take advantage of the temporal and spatial resolution that the CT scanner provides.

  16. X-ray Computed Tomography of coal: Final report

    SciTech Connect

    Maylotte, D.H.; Spiro, C.L.; Kosky, P.G.; Lamby, E.J.

    1986-12-01

    X-ray Computed Tomography (CT) is a method of mapping with x-rays the internal structures of coal. The technique normally produces 2-D images of the internal structures of an object. These images can be recast to create pseudo 3-D representations. CT of coal has been explored for a variety of different applications to coal and coal processing technology. In a comparison of CT data with conventional coal analyses and petrography, CT was found to offer a good indication of the total ash content of the coal. The spatial distribution of the coal mineral matter as seen with CT has been suggested as an indicator of coal washability. Studies of gas flow through coal using xenon gas as a tracer have shown the extremely complicated nature of the modes of penetration of gas through coal, with significant differences in the rates at which the gas can pass along and across the bedding planes of coal. In a special furnace designed to allow CT images to be taken while the coal was being heated, the pyrolysis and gasification of coal have been studied. Gasification rates with steam and CO/sub 2/ for a range of coal ranks have been obtained, and the location of the gasification reactions within the piece of coal can be seen. Coal drying and the progress of the pyrolysis wave into coal have been examined when the coal was subjected to the kind of sudden temperature jump that it might experience in fixed bed gasifier applications. CT has also been used to examine stable flow structures within model fluidized beds and the accessibility of lump coal to microbial desulfurization. 53 refs., 242 figs., 26 tabs.

  17. Note: Effect of photodiode aluminum cathode frame on spectral sensitivity in the soft x-ray energy band

    SciTech Connect

    McGarry, M. B. Den Hartog, D. J.; Goetz, J. A.; Johnson, J.; Franz, P.

    2014-09-15

    Silicon photodiodes used for soft x-ray detection typically have a thin metal electrode partially covering the active area of the photodiode, which subtly alters the spectral sensitivity of the photodiode. As a specific example, AXUV4BST photodiodes from International Radiation Detectors have a 1.0 μm thick aluminum frame covering 19% of the active area of the photodiode, which attenuates the measured x-ray signal below ∼6 keV. This effect has a small systematic impact on the electron temperature calculated from measurements of soft x-ray bremsstrahlung emission from a high-temperature plasma. Although the systematic error introduced by the aluminum frame is only a few percent in typical experimental conditions on the Madison Symmetric Torus, it may be more significant for other instruments that use similar detectors.

  18. Revealing electronic structure changes in Chevrel phase cathodes upon Mg insertion using X-ray absorption spectroscopy.

    PubMed

    Wan, Liwen F; Wright, Joshua; Perdue, Brian R; Fister, Timothy T; Kim, Soojeong; Apblett, Christopher A; Prendergast, David

    2016-06-29

    Following previous work predicting the electronic response of the Chevrel phase Mo6S8 upon Mg insertion (Thöle et al., Phys. Chem. Chem. Phys., 2015, 17, 22548), we provide the experimental proof, evident in X-ray absorption spectroscopy, to illustrate the charge compensation mechanism of the Chevrel phase compound during Mg insertion and de-insertion processes. PMID:27314253

  19. X-ray computed tomography for additive manufacturing: a review

    NASA Astrophysics Data System (ADS)

    Thompson, A.; Maskery, I.; Leach, R. K.

    2016-07-01

    In this review, the use of x-ray computed tomography (XCT) is examined, identifying the requirement for volumetric dimensional measurements in industrial verification of additively manufactured (AM) parts. The XCT technology and AM processes are summarised, and their historical use is documented. The use of XCT and AM as tools for medical reverse engineering is discussed, and the transition of XCT from a tool used solely for imaging to a vital metrological instrument is documented. The current states of the combined technologies are then examined in detail, separated into porosity measurements and general dimensional measurements. In the conclusions of this review, the limitation of resolution on improvement of porosity measurements and the lack of research regarding the measurement of surface texture are identified as the primary barriers to ongoing adoption of XCT in AM. The limitations of both AM and XCT regarding slow speeds and high costs, when compared to other manufacturing and measurement techniques, are also noted as general barriers to continued adoption of XCT and AM.

  20. Mixed polyanion glass cathodes: Glass-state conversion reactions

    SciTech Connect

    Kercher, Andrew K.; Kolopus, James A.; Carroll, Kyler; Unocic, Raymond R.; Kirklin, S.; Wolverton, C.; Stooksbury, Shelby L.; Boatner, Lynn A.; Dudney, Nancy J.

    2015-01-01

    Mixed polyanion (MP) glasses can undergo glass-state conversion (GSC) reactions to provide an alternate class of high-capacity cathode materials. GSC reactions have been demonstrated in phosphate/vanadate glasses with Ag, Co, Cu, Fe, and Ni cations. These MP glasses provided high capacity and good high power performance, but suffer from moderate voltages, large voltage hysteresis, and significant capacity fade with cycling. Details of the GSC reaction have been revealed by x-ray absorption spectroscopy, electron microscopy, and energy dispersive x-ray spectroscopy of ex situ cathodes at key states of charge. Using the Open Quantum Materials Database (OQMD), a computational thermodynamic model has been developed to predict the near-equilibrium voltages of glass-state conversion reactions in MP glasses.

  1. Mixed polyanion glass cathodes: Glass-state conversion reactions

    DOE PAGES

    Kercher, Andrew K.; Kolopus, James A.; Carroll, Kyler; Unocic, Raymond R.; Kirklin, S.; Wolverton, C.; Stooksbury, Shelby L.; Boatner, Lynn A.; Dudney, Nancy J.

    2015-01-01

    Mixed polyanion (MP) glasses can undergo glass-state conversion (GSC) reactions to provide an alternate class of high-capacity cathode materials. GSC reactions have been demonstrated in phosphate/vanadate glasses with Ag, Co, Cu, Fe, and Ni cations. These MP glasses provided high capacity and good high power performance, but suffer from moderate voltages, large voltage hysteresis, and significant capacity fade with cycling. Details of the GSC reaction have been revealed by x-ray absorption spectroscopy, electron microscopy, and energy dispersive x-ray spectroscopy of ex situ cathodes at key states of charge. Using the Open Quantum Materials Database (OQMD), a computational thermodynamic model hasmore » been developed to predict the near-equilibrium voltages of glass-state conversion reactions in MP glasses.« less

  2. Reduction-melting combined with a Na₂CO₃ flux recycling process for lead recovery from cathode ray tube funnel glass.

    PubMed

    Okada, Takashi; Yonezawa, Susumu

    2014-08-01

    With large quantity of flux (Na2CO3), lead can be recovered from the funnel glass of waste cathode-ray tubes via reduction-melting at 1000°C. To reduce flux cost, a technique to recover added flux from the generated oxide phase is also important in order to recycle the flux recovered from the reduction-melting process. In this study, the phase separation of sodium and the crystallization of water-soluble sodium silicates were induced after the reduction-melting process to enhance the leachability of sodium in the oxide phase and to extract the sodium from the phase for the recovery of Na2CO3 as flux. A reductive atmosphere promoted the phase separation and crystallization, and the leachability of sodium from the oxide phase was enhanced. The optimum temperature and treatment time for increasing the leachability were 700°C and 2h, respectively. After treatment, more than 90% of the sodium in the oxide phase was extracted in water. NaHCO3 can be recovered by carbonization of the solution containing sodium ions using carbon dioxide gas, decomposed to Na2CO3 at 50°C and recycled for use in the reduction-melting process.

  3. Nuclear Magnetic Resonance and X-Ray Absorption Spectroscopic Studies of Lithium Insertion in Silver Vanadium Oxide Cathodes

    SciTech Connect

    Leifer,N.; Colon, A.; Martocci, k.; Greenbaum, S.; Alamgir, F.; Reddy, T.; Gleason, N.; Leising, R.; Takeuchi, E.

    2007-01-01

    Structural studies have been carried out on Ag{sub 2}V{sub 4}O{sub 11} (silver vanadium oxide, SVO) and Li{sub x}Ag{sub 2}V{sub 4}O{sub 11}, lithiated SVO with x=0.72, 2.13, and 5.59 using nuclear magnetic resonance (NMR) and X-ray absorption spectroscopy (XAS). Lithium-7 NMR indicates the formation of a solid electrolyte interphase layer on the x=0.72 sample and lithium intercalation into both octahedral and tetrahedral sites in the SVO lattice, and that most but not all of the Ag (I) is reduced prior to initiation of V(V) reduction. Vanadium-51 NMR studies of SVO and lithiated SVO show decreased crystallinity with increased lithiation, as previously reported. Silver XAS studies indicate the formation of metallic silver crystallites in all the lithiated samples. A comparison of X-ray absorption near edge spectroscopy spectra for vanadium in these samples with those of reference compounds shows that some reduction of vanadium (V) occurs in the lithiated SVO with x=0.72 and increases with further lithiation leading to the formation of V(IV) and V(III) species. The results of this study indicate that vanadium(V) reduction occurs in parallel with silver (I) reduction during the initial stages of SVO lithiation, leading ultimately to the formation of vanadium (IV) and (III) species with further lithiation.

  4. Digital computer processing of X-ray photos

    NASA Technical Reports Server (NTRS)

    Nathan, R.; Selzer, R. H.

    1967-01-01

    Digital computers correct various distortions in medical and biological photographs. One of the principal methods of computer enhancement involves the use of a two-dimensional digital filter to modify the frequency spectrum of the picture. Another computer processing method is image subtraction.

  5. TPASS: a gamma-ray spectrum analysis and isotope identification computer code

    SciTech Connect

    Dickens, J.K.

    1981-03-01

    The gamma-ray spectral data-reduction and analysis computer code TPASS is described. This computer code is used to analyze complex Ge(Li) gamma-ray spectra to obtain peak areas corrected for detector efficiencies, from which are determined gamma-ray yields. These yields are compared with an isotope gamma-ray data file to determine the contributions to the observed spectrum from decay of specific radionuclides. A complete FORTRAN listing of the code and a complex test case are given.

  6. Carbon nanotube based field emission X-ray sources

    NASA Astrophysics Data System (ADS)

    Cheng, Yuan

    This dissertation describes the development of field emission (FE) x-ray sources with a carbon-nanotube (CNT) cathode. Field emission x-rays have advantages over conventional x-rays by replacing the thermionic cathode with a cold cathode so that electrons are emitted at room temperature and emission is voltage controllable. CNTs are found to be excellent electron emitters with low threshold fields and high current density which makes them ideal for generate field emission x-rays. Macroscopic CNT cold cathodes are prepared and the parameters to tune their field emission properties are studied: structure and morphology of CNT cathodes, temperature as well as electronic work function of CNT. Macroscopic CNT cathodes with optimized performance are chosen to build a high-resolution x-ray imaging system. The system can readily generate x-ray radiation with continuous variation of temporal resolution up to nanoseconds and spatial resolution down to 10 micron. Its potential applications for dynamic x-ray imaging and micro-computed tomography are also demonstrated. The performance characteristics of this compact and versatile system are promising for non-destructive testing and for non-invasive small-animal imaging for biomedical research.

  7. Computers in Communications and Education at Coast Community College District.

    ERIC Educational Resources Information Center

    Luskin, Bernard J.; Ruth, Monty W.

    Coast Community College District in Orange County, California is a leader among community colleges in the instructional use computers. The district's hardware consists of an IBM system 370 model 155 computer, over 80 typewriter terminals, 12 cathode ray tubes (CRT), and several microfiche image projection devices. Better than 700 computer-assisted…

  8. Operando and in situ X-ray spectroscopies of degradation in La0.6Sr0.4Co0.2Fe0.8O(3-δ) thin film cathodes in fuel cells.

    PubMed

    Lai, Samson Y; Ding, Dong; Liu, Mingfei; Liu, Meilin; Alamgir, Faisal M

    2014-11-01

    Information from ex situ characterization can fall short in describing complex materials systems simultaneously exposed to multiple external stimuli. Operando X-ray absorption spectroscopy (XAS) was used to probe the local atomistic and electronic structure of specific elements in a La0.6Sr0.4Co0.2Fe0.8O(3-δ) (LSCF) thin film cathode exposed to air contaminated with H2O and CO2 under operating conditions. While impedance spectroscopy showed that the polarization resistance of the LSCF cathode increased upon exposure to both contaminants at 750 °C, XAS near-edge and extended fine structure showed that the degree of oxidation for Fe and Co decreases with increasing temperature. Synchrotron-based X-ray photoelectron spectroscopy tracked the formation and removal of a carbonate species, a Co phase, and different oxygen moieties as functions of temperature and gas. The combined information provides insight into the fundamental mechanism by which H2O and CO2 cause degradation in the cathode of solid oxide fuel cells. PMID:25205041

  9. Elucidating the degradation mechanism of the cathode catalyst of PEFCs by a combination of electrochemical methods and X-ray fluorescence spectroscopy.

    PubMed

    Monzó, J; van der Vliet, D F; Yanson, A; Rodriguez, P

    2016-08-10

    In this study, we report a methodology which enables the determination of the degradation mechanisms responsible for catalyst deterioration under different accelerated stress protocols (ASPs) by combining measurements of the electrochemical surface area (ECSA) and Pt content (by X-ray fluorescence). The validation of this method was assessed on high surface area unsupported Pt nanoparticles (Pt-NPs), Pt nanoparticles supported on TaC (Pt/TaC) and Pt nanoparticles supported on Vulcan carbon (Pt/Vulcan). In the load cycle protocol, the degradation of Pt-NPs and Pt/Vulcan follows associative processes (e.g. agglomeration) in the first 2000 cycles, however, in successive cycles the degradation goes through dissociative processes such as Pt dissolution, as is evident from a similar decay of ECSA and Pt content. In contrast, the degradation mechanism for Pt nanoparticles dispersed on TaC occurs continuously through the dissociative processes (e.g. Pt dissolution or particle detachment), with similar decay rates of both Pt content and ECSA. In the start-up/shut-down protocol, high surface area Pt-NPs follow associative processes (e.g. Ostwald ripening) in the first 4000 cycles, after which the degradation continues through dissociative processes. On the other hand, dissociative mechanisms always govern the degradation of Pt/TaC under start-up/shut-down protocol conditions. Finally, we report that Pt nanoparticles supported on TaC exhibit the highest catalytic activity and long term durability of the three nanoparticle systems tested. This makes Pt/TaC a potentially valuable catalyst system for application in polymer electrolyte fuel cell cathodes. PMID:27464340

  10. Deterministic Computer-Controlled Polishing Process for High-Energy X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    A deterministic computer-controlled polishing process for large X-ray mirror mandrels is presented. Using tool s influence function and material removal rate extracted from polishing experiments, design considerations of polishing laps and optimized operating parameters are discussed

  11. Computational Astrophysics Consortium 3 - Supernovae, Gamma-Ray Bursts and Nucleosynthesis

    SciTech Connect

    Woosley, Stan

    2014-08-29

    Final project report for UCSC's participation in the Computational Astrophysics Consortium - Supernovae, Gamma-Ray Bursts and Nucleosynthesis. As an appendix, the report of the entire Consortium is also appended.

  12. Arbutin: Isolation, X-ray structure and computional studies

    NASA Astrophysics Data System (ADS)

    Nycz, Jacek E.; Malecki, Grzegorz; Morag, Monika; Nowak, Gerard; Ponikiewski, Lukasz; Kusz, Joachim; Switlicka, Anna

    2010-09-01

    Arbutin, an active component originated from Serratula quinquefolia for skin-whitening use and treating skin related allergic inflammation, was characterized by microanalysis, FTIR, UV-Vis, multinuclear NMR spectroscopy, and single crystal X-ray diffraction method. The geometries of the studied compound were optimized in singlet states using the density functional theory (DFT) method with B3LYP functional. Electronic spectra were calculated by TDDFT method. In general, the predicted bond lengths and angles are in a good agreement with the values based on the X-ray crystal structure data.

  13. Human thyroid specimen imaging by fluorescent x-ray computed tomography with synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Takeda, Tohoru; Yu, Quanwen; Yashiro, Toru; Yuasa, Tetsuya; Hasegawa, Yasuo; Itai, Yuji; Akatsuka, Takao

    1999-09-01

    Fluorescent x-ray computed tomography (FXCT) is being developed to detect non-radioactive contrast materials in living specimens. The FXCT system consists of a silicon (111) channel cut monochromator, an x-ray slit and a collimator for fluorescent x ray detection, a scanning table for the target organ and an x-ray detector for fluorescent x-ray and transmission x-ray. To reduce Compton scattering overlapped on the fluorescent K(alpha) line, incident monochromatic x-ray was set at 37 keV. The FXCT clearly imaged a human thyroid gland and iodine content was estimated quantitatively. In a case of hyperthyroidism, the two-dimensional distribution of iodine content was not uniform, and thyroid cancer had a small amount of iodine. FXCT can be used to detect iodine within thyroid gland quantitatively and to delineate its distribution.

  14. Hollow cathode apparatus

    NASA Technical Reports Server (NTRS)

    Aston, G. (Inventor)

    1984-01-01

    A hollow cathode apparatus is described, which can be rapidly and reliably started. An ignitor positioned upstream from the hollow cathode, generates a puff of plasma that flows with the primary gas to be ionized through the cathode. The plasma puff creates a high voltage breakdown between the downstream end of the cathode and a keeper electrode, to heat the cathode to an electron-emitting temperature.

  15. The cathode plasma simulation

    NASA Astrophysics Data System (ADS)

    Suksila, Thada

    Since its invention at the University of Stuttgart, Germany in the mid-1960, scientists have been trying to understand and explain the mechanism of the plasma interaction inside the magnetoplasmadynamics (MPD) thruster. Because this thruster creates a larger level of efficiency than combustion thrusters, this MPD thruster is the primary cadidate thruster for a long duration (planetary) spacecraft. However, the complexity of this thruster make it difficult to fully understand the plasma interaction in an MPD thruster while operating the device. That is, there is a great deal of physics involved: the fluid dynamics, the electromagnetics, the plasma dynamics, and the thermodynamics. All of these physics must be included when an MPD thruster operates. In recent years, a computer simulation helped scientists to simulate the experiments by programing the physics theories and comparing the simulation results with the experimental data. Many MPD thruster simulations have been conducted: E. Niewood et al.[5], C. K. J. Hulston et al.[6], K. D. Goodfellow[3], J Rossignol et al.[7]. All of these MPD computer simulations helped the scientists to see how quickly the system responds to the new design parameters. For this work, a 1D MPD thruster simulation was developed to find the voltage drop between the cathode and the plasma regions. Also, the properties such as thermal conductivity, electrical conductivity and heat capacity are temperature and pressure dependent. These two conductivity and heat capacity are usually definded as constant values in many other models. However, this 1D and 2D cylindrical symmetry MPD thruster simulations include both temperature and pressure effects to the electrical, thermal conductivities and heat capacity values interpolated from W. F. Ahtye [4]. Eventhough, the pressure effect is also significant; however, in this study the pressure at 66 Pa was set as a baseline. The 1D MPD thruster simulation includes the sheath region, which is the

  16. PM10 and PM2.5 and health risk assessment for heavy metals in a typical factory for cathode ray tube television recycling.

    PubMed

    Fang, Wenxiong; Yang, Yichen; Xu, Zhenming

    2013-01-01

    The representative waste television recycling process was chosen as the object of this study, including manual dismantling and mechanical separation of printed circuit boards (PCBs) and cathode ray tubes (CRTs) in two independent workshops. During these recycling processes, fine particulate matter and heavy metals will be released into the air to impact the environment and the health of the workers. The mass concentrations of PM2.5 (particles below 2.5 μm diameter) in mechanical and dismantling workshops ranged from 252.6 to 290.8 μg/m(3) and from 112.7 to 169.4 μg/m(3), respectively. The average concentration of PM2.5 around the workshop was 98.5 μg/m(3). Meanwhile, the contents of PM10 (particles below 10 μm diameter) were all below the risk threshold, except that (360.4 μg/m(3)) monitored in the mechanical workshop. In two workshops, Pb (20.46 and 6.935 mg/g) was the most enriched metal in the PM2.5 samples, while in PM10, the concentration of Cu (27.76 and 31.80 mg/g) was the largest. The concentration of Cd was the least in both PM10 and PM2.5. Health risk assessment showed that the total hazard indexes for non-carcinogenic metal in PM2.5 monitored in mechanical and dismantling workshops and in the southeast of the workshops were 7.61, 3.01, and 1.57, respectively, all above the safety level. Furthermore, Pb (7.28 and 3.01) might possibly have a non-carcinogenic effect on the workers in two workshops, and the sequence of the hazard quotient (HQ) through the three exposure ways was ingestion > dermal contact > inhalation. The lifetime cancer risk of four targeted metals was Cr > Ni > Pb > Cd, which could be proven in all monitoring samples. This study aims to provide a large amount of valid data for the State Environmental Protection Department to develop relevant environmental standards and for companies to improve the waste television recycling system to be more efficiently and environmentally friendly.

  17. HIGH-PERFORMANCE COMPUTING FOR THE STUDY OF EARTH AND ENVIRONMENTAL SCIENCE MATERIALS USING SYNCHROTRON X-RAY COMPUTED MICROTOMOGRAPHY.

    SciTech Connect

    FENG,H.; JONES,K.W.; MCGUIGAN,M.; SMITH,G.J.; SPILETIC,J.

    2001-10-12

    Synchrotron x-ray computed microtomography (CMT) is a non-destructive method for examination of rock, soil, and other types of samples studied in the earth and environmental sciences. The high x-ray intensities of the synchrotron source make possible the acquisition of tomographic volumes at a high rate that requires the application of high-performance computing techniques for data reconstruction to produce the three-dimensional volumes, for their visualization, and for data analysis. These problems are exacerbated by the need to share information between collaborators at widely separated locations over both local and tide-area networks. A summary of the CMT technique and examples of applications are given here together with a discussion of the applications of high-performance computing methods to improve the experimental techniques and analysis of the data.

  18. Analysis of cathode geometry to minimize cathode erosion in direct current microplasma jet

    SciTech Connect

    Causa, Federica; Ghezzi, Francesco; Caniello, Roberto; Grosso, Giovanni; Dellasega, David

    2012-12-15

    Microplasma jets are now widely used for deposition, etching, and materials processing. The present study focuses on the investigation of the influence of cathode geometry on deposition quality, for microplasma jet deposition systems in low vacuum. The interest here is understanding the influence of hydrogen on sputtering and/or evaporation of the electrodes. Samples obtained with two cathode geometries with tapered and rectangular cross-sections have been investigated experimentally by scanning electron microscopy and energy dispersion X-ray spectroscopy. Samples obtained with a tapered-geometry cathode present heavy contamination, demonstrating cathode erosion, while samples obtained with a rectangular-cross-section cathode are free from contamination. These experimental characteristics were explained by modelling results showing a larger radial component of the electric field at the cathode inner wall of the tapered cathode. As a result, ion acceleration is larger, explaining the observed cathode erosion in this case. Results from the present investigation also show that the ratio of radial to axial field components is larger for the rectangular geometry case, thus, qualitatively explaining the presence of micro-hollow cathode discharge over a wide range of currents observed in this case. In the light of the above findings, the rectangular cathode geometry is considered to be more effective to achieve cleaner deposition.

  19. Analysis of cathode geometry to minimize cathode erosion in direct current microplasma jet

    NASA Astrophysics Data System (ADS)

    Causa, Federica; Ghezzi, Francesco; Dellasega, David; Caniello, Roberto; Grosso, Giovanni

    2012-12-01

    Microplasma jets are now widely used for deposition, etching, and materials processing. The present study focuses on the investigation of the influence of cathode geometry on deposition quality, for microplasma jet deposition systems in low vacuum. The interest here is understanding the influence of hydrogen on sputtering and/or evaporation of the electrodes. Samples obtained with two cathode geometries with tapered and rectangular cross-sections have been investigated experimentally by scanning electron microscopy and energy dispersion X-ray spectroscopy. Samples obtained with a tapered-geometry cathode present heavy contamination, demonstrating cathode erosion, while samples obtained with a rectangular-cross-section cathode are free from contamination. These experimental characteristics were explained by modelling results showing a larger radial component of the electric field at the cathode inner wall of the tapered cathode. As a result, ion acceleration is larger, explaining the observed cathode erosion in this case. Results from the present investigation also show that the ratio of radial to axial field components is larger for the rectangular geometry case, thus, qualitatively explaining the presence of micro-hollow cathode discharge over a wide range of currents observed in this case. In the light of the above findings, the rectangular cathode geometry is considered to be more effective to achieve cleaner deposition.

  20. X-ray structures and computational studies of several cathinones

    NASA Astrophysics Data System (ADS)

    Nycz, Jacek E.; Malecki, Grzegorz; Zawiazalec, Marcin; Pazdziorek, Tadeusz

    2011-09-01

    2-(Ethylamino)-1-(4-methylphenyl)propan-1-one (shortly named 4-MEC) ( 1a), 1-(1,3-benzodioxol-5-yl)-2-(methylamino)propan-1-one (shortly named methylone or 3,4-methylenedioxymethcathinone) ( 1b), 1-(3,4-dimethylphenyl)-2-(methylamino)propan-1-one ( 1c), 2-methylamino-1-(4-methylphenyl)propan-1-one (shortly named mephedrone; 4-MMC or 4-methylmethcathinone) ( 1d) and 2-(methylamino)-1-phenylbutan-1-one (shortly named buphedrone) ( 1e) and their aminium salts ( 2a-e), are examples of cathinones which were characterized by FTIR, UV-Vis, multinuclear NMR spectroscopy. By single crystal X-ray diffraction method structures of 2a, 2b, 2c and 2d were determined. NMR solution spectra showed readily diagnostic H-1 and C-13 signals from methyl, ethyl, N-methyl or N-ethyl groups. The diastereotopic methylene protons of 1a appear as an ABX 3, and 1e and 2e appear as an ABMX 3 system. The geometries of the studied compounds were optimized in singlet states using the density functional theory (DFT) method with B3LYP functional. Electronic spectra were calculated by TDDFT method. In general, the predicted bond lengths and angles are in good agreement with the values based on the X-ray crystal structure data.

  1. X-ray computed tomography for virtually unrolling damaged papyri

    NASA Astrophysics Data System (ADS)

    Allegra, Dario; Ciliberto, Enrico; Ciliberto, Paolo; Petrillo, Giuseppe; Stanco, Filippo; Trombatore, Claudia

    2016-03-01

    The regular format for ancient works of literature was the papyrus roll. Recently many efforts to perform virtual restoration of this archeological artifact have been done. In fact the case of ancient rolled papyrus is very intriguing. Old papyruses are the substrates of very important historical information, probably being the use of papyrus dated to the Pre-Dynastic Period. Papyrus degradation is often very hard so that physical unrolling is sometime absolutely impossible. In this paper, authors describe their effort in setting a new virtual restoration methodology based on software manipulation of X-ray tomographic images. A realistic model, obtained by painting a hieroglyph inscription of Thutmosis III on a papyrus substrate made by the original method described by Plinius the Elder and by pigments and binders compatible with the Egyptian use (ochers with natural glue), was made for the X-ray investigation. A GE Optima 660 64 slice was used to obtain a stack of tomographic slices of the rolled model. Each slice appears as spiral. The intensity variations along the cross-sectional result from ink on the papyrus. The files were elaborated with original software, written by the use of MATLAB high-level language, and the final result was quite similar to the radiography of the physically unrolled sheet.

  2. Nanotube cathodes.

    SciTech Connect

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-11-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  3. Computer Evaluation Of Real-Time X-Ray And Acoustic Images

    NASA Astrophysics Data System (ADS)

    Jacoby, M. H.; Loe, R. S.; Dondes, P. A.

    1983-03-01

    The weakest link in the inspection process is the subjective interpretation of data by inspectors. To overcome this troublesome fact computer based analysis systems have been developed. In the field of nondestructive evaluation (NDE) there is a large class of inspections that can benefit from computer analysis. X-ray images (both film and fluoroscopic) and acoustic images lend themselves to automatic analysis as do the one-dimensional signals associated with ultrasonic, eddy current and acoustic emission testing. Computer analysis can enhance and evaluate subtle details. Flaws can be located and measured, and accept-ance decisions made by computer in a consistent and objective manner. This paper describes the interactive, computer-based analysis of real-time x-ray images and acoustic images of graphite/epoxy adhesively bonded structures.

  4. X-ray computed tomography for casting development

    NASA Astrophysics Data System (ADS)

    Georgeson, Gary E.; Crews, Alan R.; Bossi, Richard H.

    1992-09-01

    Computed tomography (CT) has been used to evaluate specific sand casting product examples for technical and economic benefits. The representative results are applicable to other casting technologies as well. CT has been shown to be cost effective in the development of new castings. The areas which would benefit include internal dimensional measurements (eliminating destructive sectioning), specific region inspections, flaw characterization in critical regions (to allow passing or informed repair of castings), and geometric acquisition for CAD/CAM. The quantitative capability of CT allows an engineering evaluation of castings based upon a correlation with performance. This quantitative measurement capability has also been used to measure the benefit of hot isostatic pressing in casting production. CT is also cost effective for engineering design and analysis by providing rapid geometry acquisition for input to computer aided design systems. This is particularly beneficial for components that do not have existing drawings or cannot be adequately defined until they are made for any reason. Presently CT can serve as an engineering aid to casting manufacturing. In order for CT evaluation to become routine in foundry applications, however, casting designers need to call it out as a measurement technique in the original casting design drawings, specifications on the application of CT must be written, contracts must include CT evaluation as a means for accepting casting quality, and lower cost CT systems must be available.

  5. X-ray computed tomography system using a multipixel photon counter

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Nagao, Jiro; Abderyim, Purkhet; Nomiya, Seiichiro; Hitomi, Keitaro; Ogawa, Akira; Sato, Shigehiro

    2008-08-01

    A photon-counting K-edge x-ray Computed Tomography (CT) system is useful for discriminating photon energy and for decreasing absorbed dose for patients. The CT system is of the first generation type and consists of an x-ray generator, a turn table, a translation stage, a two-stage controller, a multipixel photon counter (MPPC) module, a 0.5-mm-thick zinc oxide (ZnO) scintillator, a counter board (CB), and a personal computer (PC). Tomography is accomplished by repeating the translation and rotation of an object. Penetrating x-ray photons from the object are detected by the scintillator in conjunction with the MPPC module, and the event signals are counted by the CB. Without using energy discriminating, photon counting CT was carried out by controlling x-ray spectra.

  6. Optimization of X-ray tomography through a cooperative computing system in grid

    SciTech Connect

    Hasan, Moin Goraya, Major Singh

    2015-08-28

    Cooperative Computing implemented as Cooperative Computing System (CCS) in grid has been proved a considerably reliable technique to execute the tasks with real time constraints in a grid environment. This technique can be applied in many high performance distributed computing applications. HPC has a large number of applications in various fields of physics. One such application in radiation physics is X-ray tomography. X-Ray tomography contains numerous applications in various fields of science, technology and research. As the technology is changing from analog to digital in almost all the scenarios, this paper presents an idea towards the attachment of X-ray tomography assembly to HPC environment so as to obtain the highly reliable optimization.

  7. A computer program to trace seismic ray distribution in complex two-dimensional geological models

    USGS Publications Warehouse

    Yacoub, Nazieh K.; Scott, James H.

    1970-01-01

    A computer program has been developed to trace seismic rays and their amplitudes and energies through complex two-dimensional geological models, for which boundaries between elastic units are defined by a series of digitized X-, Y-coordinate values. Input data for the program includes problem identification, control parameters, model coordinates and elastic parameter for the elastic units. The program evaluates the partitioning of ray amplitude and energy at elastic boundaries, computes the total travel time, total travel distance and other parameters for rays arising at the earth's surface. Instructions are given for punching program control cards and data cards, and for arranging input card decks. An example of printer output for a simple problem is presented. The program is written in FORTRAN IV language. The listing of the program is shown in the Appendix, with an example output from a CDC-6600 computer.

  8. Occlusion culling for computer generated hologram based on ray-wavefront conversion.

    PubMed

    Wakunami, Koki; Yamashita, Hiroaki; Yamaguchi, Masahiro

    2013-09-23

    We propose a new method for occlusion culling in the computation of a hologram based on the mutual conversion between light-rays and wavefront. Since the occlusion culling is performed with light-ray information, conventional rendering techniques such as ray-tracing or image-based rendering can be employed. On the other hand, the wavefront is derived for the calculation of light propagation, the hologram of 3-D objects can be obtained in high accuracy. In the numerical experiment, we demonstrate that our approach can reproduce a high-resolution image for deep 3-D scene with correct occlusion effect between plural objects.

  9. Surface Characterization of the LCLS RF Gun Cathode

    SciTech Connect

    Brachmann, Axel; Decker, Franz-Josef; Ding, Yuantao; Dowell, David; Emma, Paul; Frisch, Josef; Gilevich, Sasha; Hays, Gregory; Hering, Philippe; Huang, Zhirong; Iverson, Richard; Loos, Henrik; Miahnahri, Alan; Nordlund, Dennis; Nuhn, Heinz-Dieter; Pianetta, Piero; Turner, James; Welch, James; White, William; Wu, Juhao; Xiang, Dao; /SLAC

    2012-06-25

    The first copper cathode installed in the LCLS RF gun was used during LCLS commissioning for more than a year. However, after high charge operation (> 500 pC), the cathode showed a decline of quantum efficiency within the area of drive laser illumination. They report results of SEM, XPS and XAS studies that were carried out on this cathode after it was removed from the gun. X-ray absorption and X-ray photoelectron spectroscopy reveal surface contamination by various hydrocarbon compounds. In addition they report on the performance of the second installed cathode with emphasis on the spatial distribution of electron emission.

  10. Recent Advances in Thermionic Cathodes

    SciTech Connect

    Ives, R. Lawrence; Miram, George; Collins, George; Falce, Louis R.

    2010-11-04

    The latest advances in thermionic cathodes, including scandate and controlled porosity reservoir cathodes, are reviewed. These new cathodes provide improved performance over conventional cathodes for many applications. Advantages and disadvantages are presented.

  11. Pulsed mode cathode

    NASA Technical Reports Server (NTRS)

    Myers, Roger M. (Inventor); Rawlin, Vinvent K. (Inventor)

    1994-01-01

    A cathode in an MPD thruster has an internal heater and utilizes low work function material. The cathode is preheated to operating temperature, and then the thruster is fired by discharging a capacitor bank in a pulse forming network.

  12. Sintered wire cathode

    DOEpatents

    Falce, Louis R.; Ives, R. Lawrence

    2009-06-09

    A porous cathode structure is fabricated from a plurality of wires which are placed in proximity to each other in elevated temperature and pressure for a sintering time. The sintering process produces the porous cathode structure which may be divided into a plurality of individual porous cathodes, one of which may be placed into a dispenser cathode support which includes a cavity for containing a work function reduction material such as BaO, CaO, and Al.sub.2O.sub.3. The work function reduction material migrates through the pores of the porous cathode from a work replenishment surface adjacent to the cavity of the dispenser cathode support to an emitting cathode surface, thereby providing a dispenser cathode which has a uniform work function and therefore a uniform electron emission.

  13. Cathodic protection -- Rectifier 47

    SciTech Connect

    Lane, W.M.

    1995-06-14

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms at the Hanford Reservation. The tank farms store radioactive waste.

  14. Cathodic protection -- Rectifier 46

    SciTech Connect

    Lane, W.M.

    1995-06-14

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms on the Hanford Reservation. The tank farms store radioactive waste.

  15. Micro hollow cathode discharges

    SciTech Connect

    Schoenbach, K.H.; Peterkin, F.E.; Verhappen, R.

    1995-12-31

    Hollow cathode discharges are glow discharges with the cathode fall and negative glow confined in a cavity in the cathode. For the discharge to develop, the cathode hole dimensions must be on the order of the mean free path. By reducing the cathode hole dimensions it is therefore possible to increase the pressure. Stable hollow cathode discharges in air have been observed at almost one atmosphere when the cathode diameter was reduced to 20 micrometers. In order to study the electrical parameters of a micro hollow cathode discharge, a set of experiments has been performed in argon at pressures in the torr range and a cathode hole diameter of 0.7 mm in molybdenum. The current-voltage characteristics and the appearance of the discharge plasma showed two distinct regions. At lower voltage or pressure the current varies linearly with voltage and the hollow cathode plasma is concentrated around the axis of the cathode hole (low glow mode). At higher values of voltage or pressure the current increases nonlinearly, up to a point where a transition into a low voltage hollow cathode arc was observed, and the plasma column expands and fills almost the entire cathode hole (high glow mode). Spectral measurements showed that the transition from the low glow mode into the high glow mode is related to an increased density of electrode vapor in the hollow cathode discharge. Up to the breakdown into a hollow cathode arc, the current voltage characteristic of the discharge has a positive slope. In this range, hollow cathode discharges can be operated in parallel without a ballast resistor.

  16. Pressed boride cathodes

    NASA Technical Reports Server (NTRS)

    Wolski, W.

    1985-01-01

    Results of experimental studies of emission cathodes made from lanthanum, yttrium, and gadolinium hexaborides are presented. Maximum thermal emission was obtained from lanthanum hexaboride electrodes. The hexaboride cathodes operated stably under conditions of large current density power draw, at high voltages and poor vacuum. A microtron electron gun with a lanthanum hexaboride cathode is described.

  17. Minimal-resource computer program for automatic generation of ocean wave ray or crest diagrams in shoaling waters

    NASA Technical Reports Server (NTRS)

    Poole, L. R.; Lecroy, S. R.; Morris, W. D.

    1977-01-01

    A computer program for studying linear ocean wave refraction is described. The program features random-access modular bathymetry data storage. Three bottom topography approximation techniques are available in the program which provide varying degrees of bathymetry data smoothing. Refraction diagrams are generated automatically and can be displayed graphically in three forms: Ray patterns with specified uniform deepwater ray density, ray patterns with controlled nearshore ray density, or crest patterns constructed by using a cubic polynomial to approximate crest segments between adjacent rays.

  18. Analytical computation of stray light in nested mirror modules for x-ray telescopes

    NASA Astrophysics Data System (ADS)

    Spiga, Daniele

    2015-09-01

    Stray light in X-ray telescopes are a well-known issue. Unlike rays focused via a double reflection by usual grazing-incidence geometries such as the Wolter-I, stray rays coming from off-axis sources are reflected only once by either the parabolic or the hyperbolic segment. Although not focused, stray light may represent a major source of background and ghost images especially when observing a field of faint sources in the vicinities of another, more intense, just outside the field of view of the telescope. The stray light problem is faced by mounting a pre-collimator in front of the mirror module, in order to shade a part of the reflective surfaces that may give rise to singly-reflected rays. Studying the expected stray light impact, and consequently designing a pre-collimator, is a typical ray-tracing problem, usually time and computation consuming, especially if we consider that rays propagate throughout a densely nested structure. This in turn requires one to pay attention to all the possible obstructions, increasing the complexity of the simulation. In contrast, approaching the problems of stray light calculation from an analytical viewpoint largely simplifies the problem, and may also ease the task of designing an effective pre-collimator. In this work we expose an analytical formalism that can be used to compute the stray light in a nested optical module in a fast and effective way, accounting for obstruction effects.

  19. Scattering-compensated cone beam x-ray luminescence computed tomography

    NASA Astrophysics Data System (ADS)

    Gao, Peng; Rong, Junyan; Pu, Huangsheng; Liu, Wenlei; Liao, Qimei; Lu, Hongbing

    2016-04-01

    X-ray luminescence computed tomography (XLCT) opens new possibilities to perform molecular imaging with x-ray. It is a dual modality imaging technique based on the principle that some nanophosphors can emit near-infrared (NIR) light when excited by x-rays. The x-ray scattering effect is a great issue in both CT and XLCT reconstruction. It has been shown that if the scattering effect compensated, the reconstruction average relative error can be reduced from 40% to 12% in the in the pencil beam XLCT. However, the scattering effect in the cone beam XLCT has not been proved. To verify and reduce the scattering effect, we proposed scattering-compensated cone beam x-ray luminescence computed tomography using an added leading to prevent the spare x-ray outside the irradiated phantom in order to decrease the scattering effect. Phantom experiments of two tubes filled with Y2O3:Eu3+ indicated that the proposed method could reduce the scattering by a degree of 30% and can reduce the location error from 1.8mm to 1.2mm. Hence, the proposed method was feasible to the general case and actual experiments and it is easy to implement.

  20. 3D chemical imaging in the laboratory by hyperspectral X-ray computed tomography

    PubMed Central

    Egan, C. K.; Jacques, S. D. M.; Wilson, M. D.; Veale, M. C.; Seller, P.; Beale, A. M.; Pattrick, R. A. D.; Withers, P. J.; Cernik, R. J.

    2015-01-01

    We report the development of laboratory based hyperspectral X-ray computed tomography which allows the internal elemental chemistry of an object to be reconstructed and visualised in three dimensions. The method employs a spectroscopic X-ray imaging detector with sufficient energy resolution to distinguish individual elemental absorption edges. Elemental distributions can then be made by K-edge subtraction, or alternatively by voxel-wise spectral fitting to give relative atomic concentrations. We demonstrate its application to two material systems: studying the distribution of catalyst material on porous substrates for industrial scale chemical processing; and mapping of minerals and inclusion phases inside a mineralised ore sample. The method makes use of a standard laboratory X-ray source with measurement times similar to that required for conventional computed tomography. PMID:26514938

  1. Characterization of Scalar Mixing in Dense Gaseous Jets Using X-Ray Computed Tomography

    NASA Astrophysics Data System (ADS)

    Dunnmon, Jared; Kim, Tae Wook; Kovscek, Anthony; Fahrig, Rebecca; Ihme, Matthias

    2014-11-01

    An experimental technique based on X-Ray Computed Tomography (XCT) is used to characterize scalar mixing of gaseous jets at Reynolds numbers up to 20,000. In this study, the mixing of a krypton jet with ambient air is considered. The high radiodensity of the krypton gas enables non-intrusive volumetric measurements of gas density and mixture composition based on spatial variations in x-ray attenuation. Comparisons to theoretical and computational results are presented, and the viability of this diagnostic technique is assessed. Important aspects of x-ray attenuation theory and practice are considered in data processing and their impacts on future development of this technique are discussed. Support from DoD through the NDSEG Fellowship Program and from NIH through S10 Shared Instrumentation Grant S10RR026714-01 are gratefully acknowledged.

  2. 3D chemical imaging in the laboratory by hyperspectral X-ray computed tomography.

    PubMed

    Egan, C K; Jacques, S D M; Wilson, M D; Veale, M C; Seller, P; Beale, A M; Pattrick, R A D; Withers, P J; Cernik, R J

    2015-01-01

    We report the development of laboratory based hyperspectral X-ray computed tomography which allows the internal elemental chemistry of an object to be reconstructed and visualised in three dimensions. The method employs a spectroscopic X-ray imaging detector with sufficient energy resolution to distinguish individual elemental absorption edges. Elemental distributions can then be made by K-edge subtraction, or alternatively by voxel-wise spectral fitting to give relative atomic concentrations. We demonstrate its application to two material systems: studying the distribution of catalyst material on porous substrates for industrial scale chemical processing; and mapping of minerals and inclusion phases inside a mineralised ore sample. The method makes use of a standard laboratory X-ray source with measurement times similar to that required for conventional computed tomography. PMID:26514938

  3. Multiple pinhole collimator based microscopic x-ray luminescence computed tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Zhu, Dianwen; Li, Changqing

    2016-03-01

    X-ray luminescence computed tomography (XLCT) is a new hybrid imaging modality, which has the capability to improve optical spatial resolution to hundreds of micrometers for deep targets. In this paper, we report a multiple pinhole collimator based microscopic X-ray luminescence computed tomography (microXLCT) system for small animal imaging. Superfine collimated X-ray pencil beams are used to excite deeply embedded phosphor particles, allowing us to obtain sub-millimeter optical spatial resolution in deep tissues. Multiple collimated X-ray beams are generated by mounting an array of pinholes in the front of a powerful X-ray tube. With multiple X-ray beams scanning, the phosphor particles in the region of the multiple beams are excited simultaneously, which requires less scanning time compared with a single beam scanning. The emitted optical photons on the top surface of the phantom are measured with an electron multiplying charge-coupled device (EMCCD) camera. Meanwhile, an X-ray detector is used to determine the X-ray beam size and position, which are used as structural guidance in the microXLCT image reconstruction. To validate the performance of our proposed multiple pinhole based microXLCT imaging system, we have performed numerical simulations and a phantom experiment. In the numerical simulations, we simulated a cylindrical phantom with two and six embedded targets, respectively. In the simulations, we used four parallel X-ray beams with the beam diameter of 0.1 mm and the beam interval of 3.2 mm. We can reconstruct deeply embedded multiple targets with a target diameter of 0.2 mm using measurements in six projections, which indicated that four parallel X-ray beam scan could reduce scanning time without comprising the reconstructed image quality. In the phantom experiment, we generated two parallel X-ray beams with the beam diameter of 0.5 mm and the beam interval of 4.2 mm. We scanned a phantom of one target with the two parallel X-ray beams. The target was

  4. Lookup tables to compute high energy cosmic ray induced atmospheric ionization and changes in atmospheric chemistry

    SciTech Connect

    Atri, Dimitra; Melott, Adrian L.; Thomas, Brian C. E-mail: melott@ku.edu

    2010-05-01

    A variety of events such as gamma-ray bursts and supernovae may expose the Earth to an increased flux of high-energy cosmic rays, with potentially important effects on the biosphere. Existing atmospheric chemistry software does not have the capability of incorporating the effects of substantial cosmic ray flux above 10 GeV. An atmospheric code, the NASA-Goddard Space Flight Center two-dimensional (latitude, altitude) time-dependent atmospheric model (NGSFC), is used to study atmospheric chemistry changes. Using CORSIKA, we have created tables that can be used to compute high energy cosmic ray (10 GeV–1 PeV) induced atmospheric ionization and also, with the use of the NGSFC code, can be used to simulate the resulting atmospheric chemistry changes. We discuss the tables, their uses, weaknesses, and strengths.

  5. High Quality Image of Biomedical Object by X-ray Refraction Based Contrast Computed Tomography

    SciTech Connect

    Hashimoto, E.; Maksimenko, A.; Hirano, K.; Hyodo, K.; Sugiyama, H.; Shimao, D.; Nishino, Y.; Ishikawa, T.; Yuasa, T.; Ichihara, S.; Arai, Y.; Ando, M.

    2007-01-19

    Recently we have developed a new Computed Tomography (CT) algorithm for refraction contrast that uses the optics of diffraction-enhanced imaging. We applied this new method to visualize soft tissue which is not visualized by the current absorption based contrast. The meaning of the contrast that appears in refraction-contrast X-ray CT images must be clarified from a biologic or anatomic point of view. It has been reported that the contrast is made with the specific gravity map with a range of approximately 10 {mu}arc sec. However, the relationship between the contrast and biologic or anatomic findings has not been investigated, to our knowledge. We compared refraction-contrast X-ray CT images with microscopic X-ray images, and we evaluated refractive indexes of pathologic lesions on phase-contrast X-ray CT images. We focused our attenuation of breast cancer and lung cancer as samples. X-ray refraction based Computed Tomography was appeared to be a pathological ability to depict the boundary between cancer nest and normal tissue, and inner structure of the disease.

  6. Preliminary experiment of fluorescent X-ray computed tomography to detect dual agents for biological study.

    PubMed

    Yu, Q; Takeda, T; Yuasa, T; Hasegawa, Y; Wu, J; Thet-Thet-Lwin; Hyodo, K; Dilmanian, F A; Itai, Y; Akatsuka, T

    2001-05-01

    The simultaneous observation of various information, such as blood flow, tissue metabolism and distribution of receptors, is quite important in order to understand the functional state of biomedical objects. The simultaneous detectability of contrast agents by fluorescent X-ray computed tomography (FXCT) with synchrotron radiation is examined in this study. The system consisted of a silicon (111) double-crystal monochromator, an X-ray slit system, a scanning table, a PIN diode, a highly purified germanium detector and an X-ray charge-coupled device (CCD) camera. The monochromatic X-ray beam energy was adjusted to 37.0 keV and collimated into a pencil beam of 1 x 1 mm. The fluorescent spectra of the K alpha lines for iodine and xenon were detected simultaneously. FXCT could image the distribution of both iodine and xenon agents in a phantom clearly and the contrast ratio was significantly better than that of transmission X-ray computed tomography images. PMID:11486409

  7. Porosity and phase fraction evolution with aging in lithium iron phosphate battery cathodes

    NASA Astrophysics Data System (ADS)

    Channagiri, Samartha A.; Nagpure, Shrikant C.; Babu, S. S.; Noble, Garret J.; Hart, Richard T.

    2013-12-01

    Rechargeable Lithium-ion batteries designed for electric vehicles operate under different charge and discharge rates, state of charge and temperature . However, aging of these batteries due to disruption of ionic or electronic conductivity while operating under these different cycling conditions has been a concern. In this research, we measured statistical distribution of porosity in the cathode as a function of aging and location within the cylindrical battery, using X-Ray micro-computed tomography. A change in porosity (∼20%) of the sample is noticed between aged and unaged samples. Concurrent X-Ray diffraction studies in these samples showed an increase (∼34%) in FePO4 phase fraction. Structural breakdown of the composite cathode material during charge and discharge cycling is proposed as a possible mechanism to rationalize the above results.

  8. Synchrotron-based X-ray computed tomography during compression loading of cellular materials

    DOE PAGES

    Cordes, Nikolaus L.; Henderson, Kevin; Stannard, Tyler; Williams, Jason J.; Xiao, Xianghui; Robinson, Mathew W. C.; Schaedler, Tobias A.; Chawla, Nikhilesh; Patterson, Brian M.

    2015-04-29

    Three-dimensional X-ray computed tomography (CT) of in situ dynamic processes provides internal snapshot images as a function of time. Tomograms are mathematically reconstructed from a series of radiographs taken in rapid succession as the specimen is rotated in small angular increments. In addition to spatial resolution, temporal resolution is important. Thus temporal resolution indicates how close together in time two distinct tomograms can be acquired. Tomograms taken in rapid succession allow detailed analyses of internal processes that cannot be obtained by other means. This article describes the state-of-the-art for such measurements acquired using synchrotron radiation as the X-ray source.

  9. Synchrotron-based X-ray computed tomography during compression loading of cellular materials

    SciTech Connect

    Cordes, Nikolaus L.; Henderson, Kevin; Stannard, Tyler; Williams, Jason J.; Xiao, Xianghui; Robinson, Mathew W. C.; Schaedler, Tobias A.; Chawla, Nikhilesh; Patterson, Brian M.

    2015-04-29

    Three-dimensional X-ray computed tomography (CT) of in situ dynamic processes provides internal snapshot images as a function of time. Tomograms are mathematically reconstructed from a series of radiographs taken in rapid succession as the specimen is rotated in small angular increments. In addition to spatial resolution, temporal resolution is important. Thus temporal resolution indicates how close together in time two distinct tomograms can be acquired. Tomograms taken in rapid succession allow detailed analyses of internal processes that cannot be obtained by other means. This article describes the state-of-the-art for such measurements acquired using synchrotron radiation as the X-ray source.

  10. Terahertz, X-ray and neutron computed tomography of an Eighteenth Dynasty Egyptian sealed pottery

    NASA Astrophysics Data System (ADS)

    Abraham, E.; Bessou, M.; Ziéglé, A.; Hervé, M.-C.; Szentmiklósi, L.; Kasztovszky, Z. S.; Kis, Z.; Menu, M.

    2014-09-01

    An Eighteenth Dynasty Egyptian sealed pottery stored at the Museum of Aquitaine (Bordeaux, France) has been investigated using terahertz radiation, X-rays and neutrons. THz computed tomography revealed nondestructively the presence of content, whereas X-rays and neutrons analyzed more precisely the fabrication process and conservation of the pottery together with the nature of this content owing to higher spatial resolution and contrast. With neutron tomography, we determined the method used to seal the jar as well as the finer structure of the inner content. Neutron-induced prompt gamma spectroscopy was finally applied to measure the elemental composition of the content, which is supposed to consist of dried germinated seeds.

  11. BraX-Ray: An X-Ray of the Brazilian Computer Science Graduate Programs

    PubMed Central

    Digiampietri, Luciano A.; Mena-Chalco, Jesús P.; Vaz de Melo, Pedro O. S.; Malheiro, Ana P. R.; Meira, Dânia N. O.; Franco, Laryssa F.; Oliveira, Leonardo B.

    2014-01-01

    Research productivity assessment is increasingly relevant for allocation of research funds. On one hand, this assessment is challenging because it involves both qualitative and quantitative analysis of several characteristics, most of them subjective in nature. On the other hand, current tools and academic social networks make bibliometric data web-available to everyone for free. Those tools, especially when combined with other data, are able to create a rich environment from which information on research productivity can be extracted. In this context, our work aims at characterizing the Brazilian Computer Science graduate programs and the relationship among themselves. We (i) present views of the programs from different perspectives, (ii) rank the programs according to each perspective and a combination of them, (iii) show correlation between assessment metrics, (iv) discuss how programs relate to another, and (v) infer aspects that boost programs' research productivity. The results indicate that programs with a higher insertion in the coauthorship network topology also possess a higher research productivity between 2004 and 2009. PMID:24728179

  12. BraX-Ray: an X-ray of the Brazilian computer science graduate programs.

    PubMed

    Digiampietri, Luciano A; Mena-Chalco, Jesús P; Vaz de Melo, Pedro O S; Malheiro, Ana P R; Meira, Dânia N O; Franco, Laryssa F; Oliveira, Leonardo B

    2014-01-01

    Research productivity assessment is increasingly relevant for allocation of research funds. On one hand, this assessment is challenging because it involves both qualitative and quantitative analysis of several characteristics, most of them subjective in nature. On the other hand, current tools and academic social networks make bibliometric data web-available to everyone for free. Those tools, especially when combined with other data, are able to create a rich environment from which information on research productivity can be extracted. In this context, our work aims at characterizing the Brazilian Computer Science graduate programs and the relationship among themselves. We (i) present views of the programs from different perspectives, (ii) rank the programs according to each perspective and a combination of them, (iii) show correlation between assessment metrics, (iv) discuss how programs relate to another, and (v) infer aspects that boost programs' research productivity. The results indicate that programs with a higher insertion in the coauthorship network topology also possess a higher research productivity between 2004 and 2009.

  13. Measuring the efficacy of a root biobarrier with x-ray computed tomography

    SciTech Connect

    Tollner, E.W.; Murphy, C.E. Jr. . Dept. of Agricultural Engineering)

    1990-08-16

    X-ray computed tomography is a useful tool for investigating soil physical properties nondestructively. There is a need to develop proper calibration relationships between soil properties and the x-ray absorption coefficient. The objective of the work was to evaluate soil factors affecting the x-ray absorption coefficient. Based on a theoretical analysis, experimental data from five soils and on results of several other investigators, it was concluded that for many applications, one calibration relationship is applicable to a wide range of soils. The montmorillinitic clay used in the study required special handling due to the extreme shrinkage of this soil upon drying. Knowledge of chemical composition enables approximations but not exact predictions of the x-ray absorption coefficient. The results suggested some reasonable alternative to exhaustive calibration for each anticipated soil condition. Quantification of root activity in terms of root growth and indirectly through water uptake is necessary for understanding plant growth dynamics. X-ray computed tomography (CT) enables qualitative as well as two quantitative outputs, one of which can lead to conclusions regarding root activity. A greenhouse study involving soil columns (Lakeland sand, bulk density 1.4 Mg/m{sup 3}) planted to soybean, Bahiagras, and control (no vegetation) was conducted in 1989. A treflan based on chemical barrier was placed in half of the soil column of each species. The mean x-ray absorption correlated to water content. Results suggested that root presence can also be indirectly inferred based on water content drawn down during planned stress events. It was concluded that x-ray CT may have a niche in soil-water-plant relation studies, particularly when plant species have large roots. 35 refs., 13 figs., 8 tabs.

  14. Synchrotron Investigations of SOFC Cathode Degradation

    SciTech Connect

    Idzerda, Yves

    2013-09-30

    The atomic variations occurring in cathode/electrolyte interface regions of La{sub 1-x}Sr{sub x}Co{sub y}Fe{sub 1-y}O{sub 3-δ} (LSCF) cathodes and other SOFC related materials have been investigated and characterized using soft X-ray Absorption Spectroscopy (XAS) and diffuse soft X-ray Resonant Scattering (XRS). X-ray Absorption Spectroscopy in the soft X-ray region (soft XAS) is shown to be a sensitive technique to quantify the disruption that occurs and can be used to suggest a concrete mechanism for the degradation. For LSC, LSF, and LSCF films, a significant degradation mechanism is shown to be Sr out-diffusion. By using the XAS spectra of hexavalent Cr in SrCrO4 and trivalent Cr in Cr2O3, the driving factor for Sr segregation was identified to be the oxygen vacancy concentration at the anode and cathode side of of symmetric LSCF/GDC/LSCF heterostructures. This is direct evidence of vacancy induced cation diffusion and is shown to be a significant indicator of cathode/electrolyte interfacial degradation. X-ray absorption spectroscopy is used to identify the occupation of the A-sites and B-sites for LSC, LSF, and LSCF cathodes doped with other transition metals, including doping induced migration of Sr to the anti-site for Sr, a significant cathode degradation indicator. By using spatially resolved valence mapping of Co, a complete picture of the surface electrochemistry can be determined. This is especially important in identifying degradation phenomena where the degradation is spatially localized to the extremities of the electrochemistry and not the average. For samples that have electrochemical parameters that are measured to be spatially uniform, the Co valence modifications were correlated to the effects of current density, overpotential, and humidity.

  15. Cathode heating mechanisms in pseudospark plasma switches

    NASA Astrophysics Data System (ADS)

    Sommerer, Timothy J.; Pak, Hoyoung; Kushner, Mark J.

    1992-10-01

    Pseudosparks, and the back-lighted thyratron (BLT) in particular, are finding increasing application as pulse power switches. An attractive feature of BLTs is that high current densities (≥ tens of kA cm-2) can be sustained from metal cathodes without auxiliary heating. The source of this current is believed to be electric-field-enhanced thermionic emission resulting from heating of the cathode by ion bombardment during commutation which ultimately melts the surface of the cathode. It is proposed that a photon-driven ionization mechanism in the interelectrode gap of the BLT is responsible for initiating the observed patterns of cathode surface melting and electron emission. A 21/2-dimensional computer model is presented that incorporates a photo-induced ionization mechanism to spread the plasma into the interelectrode gap. It predicts a melting of the cathode in a pattern similar to that which is experimentally observed, and predicts a rate of field-enhanced thermionic electron emission that is sufficient to explain the high BLT conduction current density. In the absence of these mechanisms, the model does not predict the observed large-area melting of the face of the cathode. The cathode heating rate during the BLT switching phase is maximum for operating parameters that are very close to the limit for which the switch will close (that is, the smallest possible pressure-electrode spacing product and smallest possible electrode holes).

  16. Accelerating statistical image reconstruction algorithms for fan-beam x-ray CT using cloud computing

    NASA Astrophysics Data System (ADS)

    Srivastava, Somesh; Rao, A. Ravishankar; Sheinin, Vadim

    2011-03-01

    Statistical image reconstruction algorithms potentially offer many advantages to x-ray computed tomography (CT), e.g. lower radiation dose. But, their adoption in practical CT scanners requires extra computation power, which is traditionally provided by incorporating additional computing hardware (e.g. CPU-clusters, GPUs, FPGAs etc.) into a scanner. An alternative solution is to access the required computation power over the internet from a cloud computing service, which is orders-of-magnitude more cost-effective. This is because users only pay a small pay-as-you-go fee for the computation resources used (i.e. CPU time, storage etc.), and completely avoid purchase, maintenance and upgrade costs. In this paper, we investigate the benefits and shortcomings of using cloud computing for statistical image reconstruction. We parallelized the most time-consuming parts of our application, the forward and back projectors, using MapReduce, the standard parallelization library on clouds. From preliminary investigations, we found that a large speedup is possible at a very low cost. But, communication overheads inside MapReduce can limit the maximum speedup, and a better MapReduce implementation might become necessary in the future. All the experiments for this paper, including development and testing, were completed on the Amazon Elastic Compute Cloud (EC2) for less than $20.

  17. A multiresolution approach to iterative reconstruction algorithms in X-ray computed tomography.

    PubMed

    De Witte, Yoni; Vlassenbroeck, Jelle; Van Hoorebeke, Luc

    2010-09-01

    In computed tomography, the application of iterative reconstruction methods in practical situations is impeded by their high computational demands. Especially in high resolution X-ray computed tomography, where reconstruction volumes contain a high number of volume elements (several giga voxels), this computational burden prevents their actual breakthrough. Besides the large amount of calculations, iterative algorithms require the entire volume to be kept in memory during reconstruction, which quickly becomes cumbersome for large data sets. To overcome this obstacle, we present a novel multiresolution reconstruction, which greatly reduces the required amount of memory without significantly affecting the reconstructed image quality. It is shown that, combined with an efficient implementation on a graphical processing unit, the multiresolution approach enables the application of iterative algorithms in the reconstruction of large volumes at an acceptable speed using only limited resources. PMID:20350850

  18. Optimized blind gamma-ray pulsar searches at fixed computing budget

    SciTech Connect

    Pletsch, Holger J.; Clark, Colin J.

    2014-11-01

    The sensitivity of blind gamma-ray pulsar searches in multiple years worth of photon data, as from the Fermi LAT, is primarily limited by the finite computational resources available. Addressing this 'needle in a haystack' problem, here we present methods for optimizing blind searches to achieve the highest sensitivity at fixed computing cost. For both coherent and semicoherent methods, we consider their statistical properties and study their search sensitivity under computational constraints. The results validate a multistage strategy, where the first stage scans the entire parameter space using an efficient semicoherent method and promising candidates are then refined through a fully coherent analysis. We also find that for the first stage of a blind search incoherent harmonic summing of powers is not worthwhile at fixed computing cost for typical gamma-ray pulsars. Further enhancing sensitivity, we present efficiency-improved interpolation techniques for the semicoherent search stage. Via realistic simulations we demonstrate that overall these optimizations can significantly lower the minimum detectable pulsed fraction by almost 50% at the same computational expense.

  19. Computer-simulated X-ray three-beam pinhole topographs for spherical silicon crystals.

    PubMed

    Okitsu, Kouhei

    2011-11-01

    X-ray three-beam pinhole topograph images for spherical silicon crystals were computer-simulated based on the n-beam Takagi-Taupin (T-T) equation. They were compared with those for parallel-plate crystals. The procedure to integrate the n-beam T-T equation for a crystal with an arbitrary shape has been validated in a separate paper [Okitsu et al. (2011), Acta Cryst. A67, 550-556] from comparison between experimentally obtained and computer-simulated six-beam pinhole topographs for a channel-cut silicon crystal.

  20. Step-and-shoot data acquisition and reconstruction for cardiac x-ray computed tomography

    SciTech Connect

    Hsieh Jiang; Londt, John; Vass, Melissa; Li, Jay; Tang Xiangyang; Okerlund, Darin

    2006-11-15

    Coronary artery imaging with x-ray computed tomography (CT) is one of the most recent advancements in CT clinical applications. Although existing ''state-of-the-art'' clinical protocols today utilize helical data acquisition, it suffers from the lack of ability to handle irregular heart rate and relatively high x-ray dose to patients. In this paper, we propose a step-and-shoot data acquisition protocol that significantly overcomes these shortcomings. The key to the proposed protocol is the large volume coverage (40 mm) enabled by the cone beam CT scanner, which allows the coverage of the entire heart in 3 to 4 steps. In addition, we propose a gated complementary reconstruction algorithm that overcomes the longitudinal truncation problem resulting from the cone beam geometry. Computer simulations, phantom experiments, and clinical studies were conducted to validate our approach.

  1. The analysis of high spatial resolution UV and X-ray images by computational modeling. [coronagraphs

    NASA Technical Reports Server (NTRS)

    Vesecky, J. F.; Antiochos, S. K.; Underwood, J. H.

    1978-01-01

    Very high resolution stereoscopic images of high temperature loop structures observed at UV and X-ray wavelengths in the solar corona can be used to understand physical processes in the corona. An existing computational model is described and sample results are given to demonstrate that computational modeling of coronal structures can indeed take advantage of very high resolution images. The sample results include the run of temperature and number density along a typical loop and the variation of the differential emission measure with temperature. The integration of the differential emission measure with temperature along a column commensurate with an instrument's spatial resolution is the relevant parameter obtained from UV and X-ray observations. The effects of loop geometry and energy input are examined.

  2. Step-and-shoot data acquisition and reconstruction for cardiac x-ray computed tomography.

    PubMed

    Hsieh, Jiang; Londt, John; Vass, Melissa; Li, Jay; Tang, Xiangyang; Okerlund, Darin

    2006-11-01

    Coronary artery imaging with x-ray computed tomography (CT) is one of the most recent advancements in CT clinical applications. Although existing "state-of-the-art" clinical protocols today utilize helical data acquisition, it suffers from the lack of ability to handle irregular heart rate and relatively high x-ray dose to patients. In this paper, we propose a step-and-shoot data acquisition protocol that significantly overcomes these shortcomings. The key to the proposed protocol is the large volume coverage (40 mm) enabled by the cone beam CT scanner, which allows the coverage of the entire heart in 3 to 4 steps. In addition, we propose a gated complementary reconstruction algorithm that overcomes the longitudinal truncation problem resulting from the cone beam geometry. Computer simulations, phantom experiments, and clinical studies were conducted to validate our approach.

  3. Observations on the Performance of X-Ray Computed Tomography for Dimensional Metrology

    NASA Astrophysics Data System (ADS)

    Corcoran, H. C.; Brown, S. B.; Robson, S.; Speller, R. D.; McCarthy, M. B.

    2016-06-01

    X-ray computed tomography (XCT) is a rising technology within many industries and sectors with a demand for dimensional metrology, defect, void analysis and reverse engineering. There are many variables that can affect the dimensional metrology of objects imaged using XCT, this paper focusses on the effects of beam hardening due to the orientation of the workpiece, in this case a holeplate, and the volume of material the X-rays travel through. Measurements discussed include unidirectional and bidirectional dimensions, radii of cylinders, fit point deviations of the fitted shapes and cylindricity. Results indicate that accuracy and precision of these dimensional measurements are affected in varying amounts, both by the amount of material the X-rays have travelled through and the orientation of the object.

  4. Real time method and computer system for identifying radioactive materials from HPGe gamma-ray spectroscopy

    DOEpatents

    Rowland, Mark S.; Howard, Douglas E.; Wong, James L.; Jessup, James L.; Bianchini, Greg M.; Miller, Wayne O.

    2007-10-23

    A real-time method and computer system for identifying radioactive materials which collects gamma count rates from a HPGe gamma-radiation detector to produce a high-resolution gamma-ray energy spectrum. A library of nuclear material definitions ("library definitions") is provided, with each uniquely associated with a nuclide or isotope material and each comprising at least one logic condition associated with a spectral parameter of a gamma-ray energy spectrum. The method determines whether the spectral parameters of said high-resolution gamma-ray energy spectrum satisfy all the logic conditions of any one of the library definitions, and subsequently uniquely identifies the material type as that nuclide or isotope material associated with the satisfied library definition. The method is iteratively repeated to update the spectrum and identification in real time.

  5. Multifractal analysis of mercury inclusions in quartz by X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Shibata, T.; Maruoka, T.; Echigo, T.

    2014-08-01

    In order to refine our understanding how fluid inclusions were trapped in the host minerals, we non-destructively observed mercury inclusions (liquid Hg0) in quartz samples using X-ray computed tomography (CT) technique. The X-ray CT apparatus can observe internal structures of the samples and give cross-sectional images from the transmission of the X-rays through the samples. From the cross-sectional images, we obtained three-dimensional spatial distributions of mercury inclusions, and quantitatively analyzed them using fractal and multifractal methods. Although the samples were from different mines, the resultant fractal dimensions were about 1.7 for the samples. The fractal dimensions were also close to those predicted by diffusion-limited aggregation models and percolation theory, which are controlled by the irreversible kinetics. Then, the mercury-bearing fluids were not primary fluid inclusions, but migrated into the pre-existing cracks of quartz crystals by diffusion processes.

  6. Metal artifact removal (MAR) analysis for the security inspections using the X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Cho, Hyo Sung; Woo, Tae Ho; Park, Chul Kyu

    2016-10-01

    Using the metal artifact property, it is analyzed for the X-ray computed tomography (CT) in the aspect of the security on the examined places like airport and surveillance areas. Since the importance of terror prevention strategy has been increased, the security application of X-ray CT has the significant remark. One shot X-ray image has the limitation to find out the exact shape to property in the closed box, which could be solved by the CT scanning without the tearing off the box in this work. Cleaner images can be obtained by the advanced technology if the CT scanning is utilized in the security purposes on the secured areas. A metal sample is treated by the metal artifact removal (MAR) method for the enhanced image. The mimicked explosive is experimented for the imaging processing application where the cleaner one is obtained. The procedure is explained and the further study is discussed.

  7. Development of spray coated cathodes for RITS-6.

    SciTech Connect

    Simpson, Sean; Leckbee, Joshua J.; Miller, Stephen Samuel

    2013-09-01

    This report documents work conducted in FY13 to conduct a feasibility study on thermal spray coated cathodes to be used in the RITS-6 accelerator in an attempt to improve surface uniformity and repeatability. Currently, the cathodes are coated with colloidal silver by means of painting by hand. It is believed that improving the cathode coating process could simplify experimental setup and improve flash x-ray radiographic performance. This report documents the experimental setup and summarizes the results of our feasibility study. Lastly, it describes the path forward and potential challenges that must be overcome in order to improve the process for creating uniform and repeatable silver coatings for cathodes.

  8. Microscale electromagnetic heating in heterogeneous energetic materials based on x-ray computed tomography

    DOE PAGES

    Kort-Kamp, W. J. M.; Cordes, N. L.; Ionita, A.; Glover, B. B.; Duque, A. L. Higginbotham; Perry, W. L.; Patterson, B. M.; Dalvit, D. A. R.; Moore, D. S.

    2016-04-01

    Electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. We combine structural information based on x-ray computed tomography, experimental dielectric data, and electromagnetic full-wave simulations to study microscale electromagnetic heating of realistic three-dimensional heterogeneous explosives. In conclusion, we analyze the formation of electromagnetic hot spots and thermal gradients in the explosive-binder mesostructures and compare the heating rate for various binder systems.

  9. X-ray computed tomography studies of gas storage and transport in Devonian shales

    SciTech Connect

    Lu, X.; Miao, P.; Watson, A.T. . Dept. of Chemical Engineering); Pepin, G.P.; Moss, R.M. ); Semmelbeck, M. )

    1994-07-01

    Devonian shales and other unconventional resources can be highly fractured and may have significant amounts of gas stored by adsorption. Conventional experiments are not well suited for characterizing the properties important for describing gas storage and transport in these media. Here, X-ray computed tomography scanning is used to determine gas storage in dynamic gas flow experiments on Devonian shale samples. Several important properties are obtained from these experiments, including fracture widths, adsorption isotherms, and matrix porosities and permeabilities.

  10. Computed Tomography Artifact Created by Air in the X-ray Tube Oil.

    PubMed

    Hedrick, Wayne R; Markovic, Michael A; Short, James H; Vera, Chido D

    2016-01-01

    A subtle artifact of patchy hypodensities in computed tomography images of the head mimicked acute or subacute cerebral infarct. The cause of the artifact was air in the oil of the x-ray tube. The artifact manifested only when the acquisition parameters included a rotation time of 0.5 second and a gantry tilt angle of 11 to 20 degrees. Routine quality control testing did not detect nonuniformities in the water phantom. PMID:26466108

  11. Computer models in room acoustics: The ray tracing method and the auralization algorithms

    NASA Astrophysics Data System (ADS)

    Pompei, Anna; Sumbatyan, M. A.; Todorov, N. F.

    2009-11-01

    Computer algorithms are described for constructing virtual acoustic models of various rooms that should satisfy some specific sound quality criteria. The algorithms are based on the ray tracing method, which, in the general case, allows calculation of the amplitude of an acoustic ray that survived multiple reflections from arbitrary curved surfaces. As a result, calculations of room acoustics are reduced to tracing the trajectories of all the acoustic rays in the course of their propagation with multiple reflections from reflecting surfaces to the point of their complete decay. For this approach to be used, the following physical properties of a room should be known: the geometry of the reflecting surfaces, the absorption and diffusion coefficients on each of these surfaces, and the decay law for rays propagating in air. The proposed models allow for the solution of the important problem of architectural acoustics called the auralization problem, i.e., to predict how any given audio segment will sound in any given hall on the basis of computer simulation alone, without any full-scale testing in specific halls.

  12. Energy-discriminating K-edge x-ray computed tomography system

    NASA Astrophysics Data System (ADS)

    Watanabe, Manabu; Sato, Eiichi; Abderyim, Purkhet; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Nagao, Jiro; Nomiya, Seiichiro; Hitomi, Keitaro; Ogawa, Akira; Sato, Shigehiro; Ichimaru, Toshio

    2008-08-01

    An energy-discriminating K-edge x-ray Computed Tomography (CT) system is useful for increasing contrast resolution of a target region and for diagnosing cancers utilizing a drug delivery system. The CT system is of the first generation type and consists of an x-ray generator, a turn table, a translation stage, a two-stage controller, a cadmium telluride (CdTe) detector, a charge amplifier, a shaping amplifier, a multi-channel analyzer (MCA), a counter board (CB), and a personal computer (PC). The K-edge CT is accomplished by repeating translation and rotation of an object. Penetrating x-ray spectra from the object are measured by a spectrometer utilizing the CdTe detector, amplifiers, and MCA. Both the photon energy and the energy width are selected by the MCA for discriminating photon energy. Enhanced iodine K-edge x-ray CT was performed by selecting photons with energies just beyond iodine K-edge energy of 33.2 keV.

  13. Monochromatic computed tomography with a compact laser-driven X-ray source.

    PubMed

    Achterhold, K; Bech, M; Schleede, S; Potdevin, G; Ruth, R; Loewen, R; Pfeiffer, F

    2013-01-01

    A laser-driven electron-storage ring can produce nearly monochromatic, tunable X-rays in the keV energy regime by inverse Compton scattering. The small footprint, relative low cost and excellent beam quality provide the prospect for valuable preclinical use in radiography and tomography. The monochromaticity of the beam prevents beam hardening effects that are a serious problem in quantitative determination of absorption coefficients. These values are important e.g. for osteoporosis risk assessment. Here, we report quantitative computed tomography (CT) measurements using a laser-driven compact electron-storage ring X-ray source. The experimental results obtained for quantitative CT measurements on mass absorption coefficients in a phantom sample are compared to results from a rotating anode X-ray tube generator at various peak voltages. The findings confirm that a laser-driven electron-storage ring X-ray source can indeed yield much higher CT image quality, particularly if quantitative aspects of computed tomographic imaging are considered.

  14. Experimental validation of L-shell x-ray fluorescence computed tomography imaging: phantom study.

    PubMed

    Bazalova-Carter, Magdalena; Ahmad, Moiz; Xing, Lei; Fahrig, Rebecca

    2015-10-01

    Thanks to the current advances in nanoscience, molecular biochemistry, and x-ray detector technology, x-ray fluorescence computed tomography (XFCT) has been considered for molecular imaging of probes containing high atomic number elements, such as gold nanoparticles. The commonly used XFCT imaging performed with K-shell x rays appears to have insufficient imaging sensitivity to detect the low gold concentrations observed in small animal studies. Low energy fluorescence L-shell x rays have exhibited higher signal-to-background ratio and appeared as a promising XFCT mode with greatly enhanced sensitivity. The aim of this work was to experimentally demonstrate the feasibility of L-shell XFCT imaging and to assess its achievable sensitivity. We built an experimental L-shell XFCT imaging system consisting of a miniature x-ray tube and two spectrometers, a silicon drift detector (SDD), and a CdTe detector placed at [Formula: see text] with respect to the excitation beam. We imaged a 28-mm-diameter water phantom with 4-mm-diameter Eppendorf tubes containing gold solutions with concentrations of 0.06 to 0.1% Au. While all Au vials were detectable in the SDD L-shell XFCT image, none of the vials were visible in the CdTe L-shell XFCT image. The detectability limit of the presented L-shell XFCT SDD imaging setup was 0.007% Au, a concentration observed in small animal studies.

  15. Experimental validation of L-shell x-ray fluorescence computed tomography imaging: phantom study.

    PubMed

    Bazalova-Carter, Magdalena; Ahmad, Moiz; Xing, Lei; Fahrig, Rebecca

    2015-10-01

    Thanks to the current advances in nanoscience, molecular biochemistry, and x-ray detector technology, x-ray fluorescence computed tomography (XFCT) has been considered for molecular imaging of probes containing high atomic number elements, such as gold nanoparticles. The commonly used XFCT imaging performed with K-shell x rays appears to have insufficient imaging sensitivity to detect the low gold concentrations observed in small animal studies. Low energy fluorescence L-shell x rays have exhibited higher signal-to-background ratio and appeared as a promising XFCT mode with greatly enhanced sensitivity. The aim of this work was to experimentally demonstrate the feasibility of L-shell XFCT imaging and to assess its achievable sensitivity. We built an experimental L-shell XFCT imaging system consisting of a miniature x-ray tube and two spectrometers, a silicon drift detector (SDD), and a CdTe detector placed at [Formula: see text] with respect to the excitation beam. We imaged a 28-mm-diameter water phantom with 4-mm-diameter Eppendorf tubes containing gold solutions with concentrations of 0.06 to 0.1% Au. While all Au vials were detectable in the SDD L-shell XFCT image, none of the vials were visible in the CdTe L-shell XFCT image. The detectability limit of the presented L-shell XFCT SDD imaging setup was 0.007% Au, a concentration observed in small animal studies. PMID:26839910

  16. Experimental validation of L-shell x-ray fluorescence computed tomography imaging: phantom study

    PubMed Central

    Bazalova-Carter, Magdalena; Ahmad, Moiz; Xing, Lei; Fahrig, Rebecca

    2015-01-01

    Abstract. Thanks to the current advances in nanoscience, molecular biochemistry, and x-ray detector technology, x-ray fluorescence computed tomography (XFCT) has been considered for molecular imaging of probes containing high atomic number elements, such as gold nanoparticles. The commonly used XFCT imaging performed with K-shell x rays appears to have insufficient imaging sensitivity to detect the low gold concentrations observed in small animal studies. Low energy fluorescence L-shell x rays have exhibited higher signal-to-background ratio and appeared as a promising XFCT mode with greatly enhanced sensitivity. The aim of this work was to experimentally demonstrate the feasibility of L-shell XFCT imaging and to assess its achievable sensitivity. We built an experimental L-shell XFCT imaging system consisting of a miniature x-ray tube and two spectrometers, a silicon drift detector (SDD), and a CdTe detector placed at ±120  deg with respect to the excitation beam. We imaged a 28-mm-diameter water phantom with 4-mm-diameter Eppendorf tubes containing gold solutions with concentrations of 0.06 to 0.1% Au. While all Au vials were detectable in the SDD L-shell XFCT image, none of the vials were visible in the CdTe L-shell XFCT image. The detectability limit of the presented L-shell XFCT SDD imaging setup was 0.007% Au, a concentration observed in small animal studies. PMID:26839910

  17. Image segmentation of nanoscale Zernike phase contrast X-ray computed tomography images

    SciTech Connect

    Kumar, Arjun S.; Mandal, Pratiti; Zhang, Yongjie; Litster, Shawn

    2015-05-14

    Zernike phase contrast is a useful technique for nanoscale X-ray computed tomography (CT) imaging of materials with a low X-ray absorption coefficient. It enhances the image contrast by phase shifting X-ray waves to create changes in amplitude. However, it creates artifacts that hinder the use of traditional image segmentation techniques. We propose an image restoration method that models the X-ray phase contrast optics and the three-dimensional image reconstruction method. We generate artifact-free images through an optimization problem that inverts this model. Though similar approaches have been used for Zernike phase contrast in visible light microscopy, this optimization employs an effective edge detection method tailored to handle Zernike phase contrast artifacts. We characterize this optics-based restoration method by removing the artifacts in and thresholding multiple Zernike phase contrast X-ray CT images to produce segmented results that are consistent with the physical specimens. We quantitatively evaluate and compare our method to other segmentation techniques to demonstrate its high accuracy.

  18. High Speed Data Acquisition System for Three-Dimensional X-Ray and Neutron Computed Tomography

    SciTech Connect

    Davis, A.W.; Claytor, T.N.; Sheats, M.J.

    1999-07-01

    Computed tomography for nondestructive evaluation applications has been limited by system cost, resolution, and time requirements for three-dimensional data sets. FlashCT (Flat panel Amorphous Silicon High-Resolution Computed Tomography) is a system developed at Los Alamos National Laboratory to address these three problems. Developed around a flat panel amorphous silicon detector array, FlashCT is suitable for low to medium energy x-ray and neutron computed tomography at 127-micron resolution. Overall system size is small, allowing rapid transportation to a variety of radiographic sources. System control software was developed in LabVIEW for Windows NT to allow multithreading of data acquisition, data correction, and staging motor control. The system control software simplifies data collection and allows fully automated control of the data acquisition process, leading toward remote or unattended operation. The first generation of the FlashCT Data Acquisition System was completed in Au gust 1998, and since that time the system has been tested using x-ray sources ranging in energy from 60 kV to 20MV. The system has also been used to collect data for thermal neutron computed tomography at Los Alamos Neutron Science Center (LANSCE). System improvements have been proposed to provide faster data collection and greater dynamic range during data collection.

  19. [Contribution of X-ray computed tomography in the evaluation of kidney performance].

    PubMed

    Lemoine, Sandrine; Rognant, Nicolas; Collet-Benzaquen, Diane; Juillard, Laurent

    2012-07-01

    X-ray computer assisted tomography scanner is an imaging method based on the use of X-ray attenuation in tissue. This attenuation is proportional to the density of the tissue (without or after contrast media injection) in each pixel image of the image. Spiral scanner, the electron beam computed tomography (EBCT) scanner and multidetector computed tomography scanner allow renal anatomical measurements, such as cortical and medullary volume, but also the measurement of renal functional parameters, such as regional renal perfusion, renal blood flow and glomerular filtration rate. These functional parameters are extracted from the modeling of the kinetics of the contrast media concentration in the vascular space and the renal tissue, using two main mathematical models (the gamma variate model and the Patlak model). Renal functional imaging allows measuring quantitative parameters on each kidney separately, in a non-invasive manner, providing significant opportunities in nephrology, both for experimental and clinical studies. However, this method uses contrast media that may alter renal function, thus limiting its use in patients with chronic renal failure. Moreover, the increase irradiation delivered to the patient with multi detector computed tomography (MDCT) should be considered. PMID:22019734

  20. Zinc/air cell cathode

    NASA Astrophysics Data System (ADS)

    McEvoy, J. J.

    1986-04-01

    This invention relates to a cathode for an air depolarized cell in which the hydrophobic catalytic cathode contains or in integrally drophobi catalytic cathode contains or is integrally coated with, on the surface adjacent the cell separator, an absorbent material such as the gelling material used in the anode. The absorbent material, integrated with the cathode surface, adheres the separator to the cathode thereby preventing delamination and provides an electrolyte reservoir for the hydrophobic cathode.

  1. Thermionic Cathode Project

    NASA Astrophysics Data System (ADS)

    Getty, W. D.; Herniter, M. E.

    1986-01-01

    A planar cathode, Pierce type electron gun with a design perveance of .0000032 (amps/volts to the 3/2 power) has been operated with a lanthanum hexaboride (LaB6) cathode. The cathode (useful diameter 1.9 cm) is heated by bombardment by electrons from a small tungsten filament. The bombardment heating system is stabilized by a feedback control circuit. The power required to heat the cathode is 315 W bombardment power and 200 W filament power. Heating power has been reduced by careful heat shielding and reduction of heat conduction losses. Significant additional reductions should be possible. The sintered LaB6 cathode disk is 2.5 cm in diameter, 3.2 mm thick, and has a density of 94%. No problems have been encountered with cracking of the disk. Cathode emission is insensitive to repeated exposure to air after allowing the cathode to fully cool. The measured perveance and anode transmission of the gun are 3.2x10(-6) and 94%, respectively. Current densities up to 6.5 A/sq cm have been reached with 5 micrometer pulses. Measurements were made at cathode temperatures of 1300 to 1600 C.

  2. Cone beam x-ray luminescence computed tomography: A feasibility study

    SciTech Connect

    Chen Dongmei; Zhu Shouping; Yi Huangjian; Zhang Xianghan; Chen Duofang; Liang Jimin; Tian Jie

    2013-03-15

    Purpose: The appearance of x-ray luminescence computed tomography (XLCT) opens new possibilities to perform molecular imaging by x ray. In the previous XLCT system, the sample was irradiated by a sequence of narrow x-ray beams and the x-ray luminescence was measured by a highly sensitive charge coupled device (CCD) camera. This resulted in a relatively long sampling time and relatively low utilization of the x-ray beam. In this paper, a novel cone beam x-ray luminescence computed tomography strategy is proposed, which can fully utilize the x-ray dose and shorten the scanning time. The imaging model and reconstruction method are described. The validity of the imaging strategy has been studied in this paper. Methods: In the cone beam XLCT system, the cone beam x ray was adopted to illuminate the sample and a highly sensitive CCD camera was utilized to acquire luminescent photons emitted from the sample. Photons scattering in biological tissues makes it an ill-posed problem to reconstruct the 3D distribution of the x-ray luminescent sample in the cone beam XLCT. In order to overcome this issue, the authors used the diffusion approximation model to describe the photon propagation in tissues, and employed the sparse regularization method for reconstruction. An incomplete variables truncated conjugate gradient method and permissible region strategy were used for reconstruction. Meanwhile, traditional x-ray CT imaging could also be performed in this system. The x-ray attenuation effect has been considered in their imaging model, which is helpful in improving the reconstruction accuracy. Results: First, simulation experiments with cylinder phantoms were carried out to illustrate the validity of the proposed compensated method. The experimental results showed that the location error of the compensated algorithm was smaller than that of the uncompensated method. The permissible region strategy was applied and reduced the reconstruction error to less than 2 mm. The robustness

  3. Thermal stability in the blended lithium manganese oxide - Lithium nickel cobalt manganese oxide cathode materials: An in situ time-resolved X-Ray diffraction and mass spectroscopy study

    NASA Astrophysics Data System (ADS)

    Hu, Enyuan; Bak, Seong Min; Senanayake, Sanjaya D.; Yang, Xiao-Qing; Nam, Kyung-Wan; Zhang, Lulu; Shao, Minhua

    2015-03-01

    Thermal stabilities of a series of blended LiMn2O4 (LMO)-LiNi1/3Co1/3Mn1/3O2 (NCM) cathode materials with different weight ratios were studied by in situ time-resolved X-ray diffraction (XRD) combined with mass spectroscopy in the temperature range of 25 °C-580 °C under helium atmosphere. Upon heating, the electrochemically delithiated LMO changed into Mn3O4 phase at around 250 °C. Formation of MnO with rock-salt structure started at 520 °C. This observation is in contrast to the previous report for chemically delithiated LMO in air, in which a process of λ-MnO2 transforming to β-MnO2 was observed. Oxygen peak was not observed in all cases, presumably as a result of either consumption by the carbon or detection limit. CO2 profile correlates well with the phase transition and indirectly suggests the oxygen release of the cathode. Introducing NCM into LMO has two effects: first, it makes the high temperature rock-salt phase formation more complicated with more peaks in CO2 profile due to different MO (M = Ni, Mn, Co) phases; secondly, the onset temperature of CO2 release is lowered, implying lowered oxygen release temperature. Upon heating, XRD patterns indicate the NCM part reacts first, followed by the LMO part. This confirms the better thermal stability of LMO over NCM.

  4. Thermal stability in the blended lithium manganese oxide – Lithium nickel cobalt manganese oxide cathode materials: An in situ time-resolved X-Ray diffraction and mass spectroscopy study

    SciTech Connect

    Hu, Enyuan; Bak, Seong Min; Senanayake, Sanjaya D.; Yang, Xiao-Qing; Nam, Kyung-Wan; Zhang, Lulu; Shao, Minhua

    2015-03-01

    Thermal stabilities of a series of blended LiMn2O4(LMO)-LiNi1/3Co1/3Mn1/3O2 (NCM) cathode materials with different weight ratios were studied by in situ time-resolved X-ray diffraction (XRD) combined with mass spectroscopy in the temperature range of 25°C-580°C under helium atmosphere. Upon heating, the electrochemically delithiated LMO changed into Mn3O4 phase at around 250°C. Formation of MnO with rocksalt structure started at 520°C. This observation is in contrast to the previous report for chemically delithiate LMO in air, in which a process of λ-MnO2 transforming to β-MnO2 was observed. Oxygen peak was not observed in all cases, presumably as a result of either consumption by the carbon or detection limit. CO2 profile correlates well with the phase transition and indirectly suggests the oxygen release of the cathode. Introducing NCM into LMO has two effects: first, it makes the high temperature rock-salt phase formation more complicated with more peaks in CO2 profile due to different MO (M = Ni, Mn, Co) phases; secondly, the onset temperature of CO2 release is lowered, implying lowered oxygen release temperature. Upon heating, XRD patterns indicate the NCM part reacts first, followed by the LMO part. This confirms the better thermal stability of LMO over NCM.

  5. Thermal stability in the blended lithium manganese oxide – Lithium nickel cobalt manganese oxide cathode materials: An in situ time-resolved X-Ray diffraction and mass spectroscopy study

    DOE PAGES

    Hu, Enyuan; Bak, Seong Min; Senanayake, Sanjaya D.; Yang, Xiao-Qing; Nam, Kyung-Wan; Zhang, Lulu; Shao, Minhua

    2015-03-01

    Thermal stabilities of a series of blended LiMn2O4(LMO)-LiNi1/3Co1/3Mn1/3O2 (NCM) cathode materials with different weight ratios were studied by in situ time-resolved X-ray diffraction (XRD) combined with mass spectroscopy in the temperature range of 25°C-580°C under helium atmosphere. Upon heating, the electrochemically delithiated LMO changed into Mn3O4 phase at around 250°C. Formation of MnO with rocksalt structure started at 520°C. This observation is in contrast to the previous report for chemically delithiate LMO in air, in which a process of λ-MnO2 transforming to β-MnO2 was observed. Oxygen peak was not observed in all cases, presumably as a result of either consumptionmore » by the carbon or detection limit. CO2 profile correlates well with the phase transition and indirectly suggests the oxygen release of the cathode. Introducing NCM into LMO has two effects: first, it makes the high temperature rock-salt phase formation more complicated with more peaks in CO2 profile due to different MO (M = Ni, Mn, Co) phases; secondly, the onset temperature of CO2 release is lowered, implying lowered oxygen release temperature. Upon heating, XRD patterns indicate the NCM part reacts first, followed by the LMO part. This confirms the better thermal stability of LMO over NCM.« less

  6. Computer Terminal Selection: Some Instructional and Psychological Implications.

    ERIC Educational Resources Information Center

    Brown, Bobby R.; O'Neil, Harold F.

    Factors which have previously provided the basis for decisions as to the use of CRT (cathode ray tube) of teletype terminals in computer-assisted instruction (CAI) may be decreasing in importance. Specifically, differential cost factors and teleprocessing capability may no longer provide a basis for differentiating between CRTs and teletypes. In…

  7. An Architectural Design System Based on Computer Graphics.

    ERIC Educational Resources Information Center

    MacDonald, Stephen L.; Wehrli, Robert

    The recent developments in computer hardware and software are presented to inform architects of this design tool. Technical advancements in equipment include--(1) cathode ray tube displays, (2) light pens, (3) print-out and photo copying attachments, (4) controls for comparison and selection of images, (5) chording keyboards, (6) plotters, and (7)…

  8. Response Mode Effects on Computer Based Problem Solving.

    ERIC Educational Resources Information Center

    Sustik, Joan M.; Brown, Bobby R.

    Assessments were made of the impact of various overt response modes on the problem-solving process. The Luchins Water Jar Problems were presented to undergraduate university students via interactive cathode ray tube computer terminals under four response mode conditions: Mnemonic Code, Multiple Choice (MC), Numerical List, and Constructed Response…

  9. It Is Worth Thoroughly Looking at the Computer Display

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2009-01-01

    Two useful observations are possible when thoroughly looking at the cathode-ray display of a computer. First, the structure of a color image is seen with a moderate magnification. Second, the decay of different phosphors corresponding to the red, green, and blue primary colors is observable with a photodiode and oscilloscope.

  10. An X-ray Absorption Spectroscopy Study of the Cathodic Discharge of Ag2VO2PO4: Geometric and Electronic Structure Characterization of Intermediate Phases and Mechanistic Insights

    SciTech Connect

    C Patridge; C Jaye; T Abtew; B Ravel; D Fischer; A Marschilok; P Zhang; K Takeuchi; E Takeuchi; S Baneerjee

    2011-12-31

    Bimetallic phosphorus oxides have emerged as attractive candidates for use as cathode materials in the next generation of lithium-based batteries owing to the operation of multielectron transfer processes and thermochemical stabilities conferred by the incorporation of phosphate groups. In particular silver vanadium phosphorus oxide, Ag{sub 2}VO{sub 2}PO{sub 4}, shows a much desired in situ conductivity enhancement upon discharge resulting in inherently high power capability with minimal conductive additives needed. However, the amorphization of Ag{sub 2}VO{sub 2}PO{sub 4} during electrochemical discharge precludes the use of standard diffraction tools to monitor changes in the local electronic and geometric structure. Here, we have utilized a combination of V K-, V L-, Ag K-, and O K-edge X-ray absorption fine structure spectroscopy to determine the local vanadium and silver oxidation states, local coordination geometry, and stoichiometry for Ag{sub 2}VO{sub 2}PO{sub 4} samples with varying extents of electrochemical lithiation. Soft X-ray V L- and O K-edge measurements provide a detailed orbital-specific picture of changes in vanadium electronic structure upon discharge.

  11. In Situ X-ray Absorption and Diffraction Studies of Carbon Coated LiFe1/4Mn1/4Co1/4Ni1/4PO4 Cathode During First Charge

    SciTech Connect

    Nam,K.W.; Yang,X.

    2009-04-01

    Synchrotron based in situ X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) techniques are used to study electronic and crystal structure changes of the carbon coated LiFe1/4Mn1/4Co1/4Ni1/4PO4 (LiFe1/4Mn1/4Co1/4Ni1/4PO4/C) cathode material for Li-ion batteries during the first charge. In situ Fe, Mn, Co and Ni K-edge XAS results revealed that the three voltage plateaus at 3.6, 4.2 and 4.7 V vs. Li/Li+ are attributed to the redox reactions of Fe2+/Fe3+, Mn2+/Mn3+ and Co2+/Co3+, respectively, while the apparent capacities above 4.9 V is not originated from the Ni2+/Ni3+ redox, but very likely from the electrolyte decomposition. Interesting phase transition behaviors of LiFe1/4Mn1/4Co1/4Ni1/4PO4/C wereobserved with the formation of an intermediate phase and the solid solution regions. Combined in situ XAS and XRD techniques indicate fast electronic structural changes and slow bulk crystal structural changes.

  12. The CT Scanner Facility at Stellenbosch University: An open access X-ray computed tomography laboratory

    NASA Astrophysics Data System (ADS)

    du Plessis, Anton; le Roux, Stephan Gerhard; Guelpa, Anina

    2016-10-01

    The Stellenbosch University CT Scanner Facility is an open access laboratory providing non-destructive X-ray computed tomography (CT) and a high performance image analysis services as part of the Central Analytical Facilities (CAF) of the university. Based in Stellenbosch, South Africa, this facility offers open access to the general user community, including local researchers, companies and also remote users (both local and international, via sample shipment and data transfer). The laboratory hosts two CT instruments, i.e. a micro-CT system, as well as a nano-CT system. A workstation-based Image Analysis Centre is equipped with numerous computers with data analysis software packages, which are to the disposal of the facility users, along with expert supervision, if required. All research disciplines are accommodated at the X-ray CT laboratory, provided that non-destructive analysis will be beneficial. During its first four years, the facility has accommodated more than 400 unique users (33 in 2012; 86 in 2013; 154 in 2014; 140 in 2015; 75 in first half of 2016), with diverse industrial and research applications using X-ray CT as means. This paper summarises the existence of the laboratory's first four years by way of selected examples, both from published and unpublished projects. In the process a detailed description of the capabilities and facilities available to users is presented.

  13. Mcps-range photon-counting x-ray computed tomography system

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Oda, Yasuyuki; Abudurexiti, Abulajiang; Hagiwara, Osahiko; Enomoto, Toshiyuki; Sugimura, Shigeaki; Endo, Haruyuki; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2011-10-01

    10 Mcps photon counting was carried out using a detector consisting of a 2.0 mm-thick ZnO (zinc oxide) single-crystal scintillator and an MPPC (multipixel photon counter) module in an X-ray computed tomography (CT) system. The maximum count rate was 10 Mcps (mega counts per second) at a tube voltage of 70 kV and a tube current of 2.0 mA. Next, a photon-counting X-ray CT system consists of an X-ray generator, a turntable, a scan stage, a two-stage controller, the ZnO-MPPC detector, a counter card (CC), and a personal computer (PC). Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan with a scan velocity of 25 mm/s. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. The exposure time for obtaining a tomogram was 600 s at a scan step of 0.5 mm and a rotation step of 1.0°, and photon-counting CT was accomplished using iodine-based contrast media.

  14. High-resolution x-ray computed tomography to understand ruminant phylogeny

    NASA Astrophysics Data System (ADS)

    Costeur, Loic; Schulz, Georg; Müller, Bert

    2014-09-01

    High-resolution X-ray computed tomography has become a vital technique to study fossils down to the true micrometer level. Paleontological research requires the non-destructive analysis of internal structures of fossil specimens. We show how X-ray computed tomography enables us to visualize the inner ear of extinct and extant ruminants without skull destruction. The inner ear, a sensory organ for hearing and balance has a rather complex three-dimensional morphology and thus provides relevant phylogenetical information what has been to date essentially shown in primates. We made visible the inner ears of a set of living and fossil ruminants using the phoenix x-ray nanotom®m (GE Sensing and Inspection Technologies GmbH). Because of the high absorbing objects a tungsten target was used and the experiments were performed with maximum accelerating voltage of 180 kV and a beam current of 30 μA. Possible stem ruminants of the living families are known in the fossil record but extreme morphological convergences in external structures such as teeth is a strong limitation to our understanding of the evolutionary history of this economically important group of animals. We thus investigate the inner ear to assess its phylogenetical potential for ruminants and our first results show strong family-level morphological differences.

  15. Optimal Contrast Agent Staining of Ligaments and Tendons for X-Ray Computed Tomography

    PubMed Central

    Balint, Richard; Lowe, Tristan

    2016-01-01

    X-ray computed tomography has become an important tool for studying the microstructures of biological soft tissues, such as ligaments and tendons. Due to the low X-ray attenuation of such tissues, chemical contrast agents are often necessary to enhance contrast during scanning. In this article, the effects of using three different contrast agents—iodine potassium iodide solution, phosphotungstic acid and phosphomolybdic acid—are evaluated and compared. Porcine anterior cruciate ligaments, patellar tendons, medial collateral ligaments and lateral collateral ligaments were used as the basis of the study. Three samples of each of the four ligament/tendon types were each assigned a different contrast agent (giving a total of twelve samples), and the progression of that agent through the tissue was monitored by performing a scan every day for a total period of five days (giving a total of sixty scans). Since the samples were unstained on day one, they had been stained for a total of four days by the time of the final scans. The relative contrast enhancement and tissue deformation were measured. It was observed that the iodine potassium iodide solution penetrated the samples fastest and caused the least sample shrinkage on average (although significant deformation was observed by the time of the final scans), whereas the phosphomolybdic acid caused the greatest sample shrinkage. Equations describing the observed behaviour of the contrast agents, which can be used to predict optimal staining times for ligament and tendon X-ray computed tomography, are presented. PMID:27078030

  16. Optimal Contrast Agent Staining of Ligaments and Tendons for X-Ray Computed Tomography.

    PubMed

    Balint, Richard; Lowe, Tristan; Shearer, Tom

    2016-01-01

    X-ray computed tomography has become an important tool for studying the microstructures of biological soft tissues, such as ligaments and tendons. Due to the low X-ray attenuation of such tissues, chemical contrast agents are often necessary to enhance contrast during scanning. In this article, the effects of using three different contrast agents--iodine potassium iodide solution, phosphotungstic acid and phosphomolybdic acid--are evaluated and compared. Porcine anterior cruciate ligaments, patellar tendons, medial collateral ligaments and lateral collateral ligaments were used as the basis of the study. Three samples of each of the four ligament/tendon types were each assigned a different contrast agent (giving a total of twelve samples), and the progression of that agent through the tissue was monitored by performing a scan every day for a total period of five days (giving a total of sixty scans). Since the samples were unstained on day one, they had been stained for a total of four days by the time of the final scans. The relative contrast enhancement and tissue deformation were measured. It was observed that the iodine potassium iodide solution penetrated the samples fastest and caused the least sample shrinkage on average (although significant deformation was observed by the time of the final scans), whereas the phosphomolybdic acid caused the greatest sample shrinkage. Equations describing the observed behaviour of the contrast agents, which can be used to predict optimal staining times for ligament and tendon X-ray computed tomography, are presented.

  17. Porous Media Contamination: 3-Dimensional Visualization and Quantification Using X-Ray Computed Tomography

    NASA Astrophysics Data System (ADS)

    Goldstein, L.; Prasher, S. O.; Ghoshal, S.

    2004-05-01

    Non-aqueous phase liquids (NAPLs), if spilled into the subsurface, will migrate downward, and a significant fraction will become trapped in the soil matrix. These trapped NAPL globules partition into the water and/or vapor phase, and serve as continuous sources of contamination (e.g. source zones). At present, the presence of NAPL in the subsurface is typically inferred from chemical analysis data. There are no accepted methodologies or protocols available for the direct characterization of NAPLs in the subsurface. Proven and cost-effective methodologies are needed to allow effective implementation of remediation technologies at NAPL contaminated sites. X-ray Computed Tomography (CT) has the potential to non-destructively quantify NAPL mass and distribution in soil cores due to this technology's ability to detect small atomic density differences of solid, liquid, gas, and NAPL phases present in a representative volume element. We have demonstrated that environmentally significant NAPLs, such as gasoline and other oil products, chlorinated solvents, and PCBs possess a characteristic and predictable X-ray attenuation coefficient that permits their quantification in porous media at incident beam energies, typical of medical and industrial X-ray CT scanners. As part of this study, methodologies were developed for generating and analyzing X-ray CT data for the study of NAPLs in natural porous media. Columns of NAPL-contaminated soils were scanned, flushed with solvents and water to remove entrapped NAPL, and re-scanned. X-ray CT data was analyzed to obtain numerical arrays of soil porosity, NAPL saturation, and NAPL volume at a spatial resolution of 1 mm. This methodology was validated using homogeneous and heterogeneous soil columns with known quantities of gasoline and tetrachloroethylene. NAPL volumes computed using X-ray CT data was compared with known volumes from volume balance calculations. Error analysis revealed that in a 5 cm long and 2.5 cm diameter soil

  18. Identifying unknown minerals and compounds from X-ray diffraction patterns using the Johnson and Vand FORTRAN 4 computer program

    NASA Technical Reports Server (NTRS)

    Kyte, F. T.

    1976-01-01

    Automated computer identification of minerals and compounds from unknown samples is provided along with detailed instructions and worked examples for use in graduate level courses in mineralogy and X-ray analysis applications.

  19. Geometric classification of open-cell metal foams using X-ray micro-computed tomography

    SciTech Connect

    Bock, Jessica Jacobi, Anthony M.

    2013-01-15

    The geometry of foams has long been an area of interest, and a number of idealized geometric descriptions have been proposed. In order to acquire detailed, quantitative, geometric data for aluminum open-cell metal foams, X-ray {mu}CT is employed. The X-ray {mu}CT images are analyzed using specialized software, FoamView Registered-Sign , from which geometric information including strut length and pore shapes are extracted. The X-ray {mu}CT analysis allows comparison of the ideal geometric models to the actual geometric characteristics of the metal foam samples. The results reveal a high variability in ligament length, as well as features supporting the ideal geometry known as the Weaire-Phelan unit cell. The geometric findings provide information useful for improving current models of open-cell metal foam. Applications can range from predicting heat transfer or load failure to predicting liquid retention. Highlights: Black-Right-Pointing-Pointer Aluminum open-cell metal foams are geometrically classified Black-Right-Pointing-Pointer X-ray micro-computed tomography and specialized software are used to gather geometric data Black-Right-Pointing-Pointer The foams are shown to have a high variability in strut length Black-Right-Pointing-Pointer The Weaire-Phelan unit cell is shown to be a better representative of these foams.

  20. Progress in Cell Marking for Synchrotron X-ray Computed Tomography

    SciTech Connect

    Hall, Christopher; Sturm, Erica; Schultke, Elisabeth; Arfelli, Fulvia; Astolfo, Alberto; Menk, Ralf-Hendrik; Juurlink, Bernhard H. J.

    2010-07-23

    Recently there has been an increase in research activity into finding ways of marking cells in live animals for pre-clinical trials. Development of certain drugs and other therapies crucially depend on tracking particular cells or cell types in living systems. Therefore cell marking techniques are required which will enable longitudinal studies, where individuals can be examined several times over the course of a therapy or study. The benefits of being able to study both disease and therapy progression in individuals, rather than cohorts are clear. The need for high contrast 3-D imaging, without harming or altering the biological system requires a non-invasive yet penetrating imaging technique. The technique will also have to provide an appropriate spatial and contrast resolution. X-ray computed tomography offers rapid acquisition of 3-D images and is set to become one of the principal imaging techniques in this area. Work by our group over the last few years has shown that marking cells with gold nano-particles (GNP) is an effective means of visualising marked cells in-vivo using x-ray CT. Here we report the latest results from these studies. Synchrotron X-ray CT images of brain lesions in rats taken using the SYRMEP facility at the Elettra synchrotron in 2009 have been compared with histological examination of the tissues. Some deductions are drawn about the visibility of the gold loaded cells in both light microscopy and x-ray imaging.

  1. X-ray computed tomography of the anterior cruciate ligament and patellar tendon

    PubMed Central

    Shearer, Tom; Rawson, Shelley; Castro, Simon Joseph; Balint, Richard; Bradley, Robert Stephen; Lowe, Tristan; Vila-Comamala, Joan; Lee, Peter David; Cartmell, Sarah Harriet

    2014-01-01

    Summary The effect of phosphotungstic acid (PTA) and iodine solution (IKI) staining was investigated as a method of enhancing contrast in the X-ray computed tomography of porcine anterior cruciate ligaments (ACL) and patellar tendons (PT). We show that PTA enhanced surface contrast, but was ineffective at penetrating samples, whereas IKI penetrated more effectively and enhanced contrast after 70 hours of staining. Contrast enhancement was compared when using laboratory and synchrotron based X-ray sources. Using the laboratory source, PT fascicles were tracked and their alignment was measured. Individual ACL fascicles could not be identified, but identifiable features were evident that were tracked. Higher resolution scans of fascicle bundles from the PT and ACL were obtained using synchrotron imaging techniques. These scans exhibited greater contrast between the fascicles and matrix in the PT sample, facilitating the identification of the fascicle edges; however, it was still not possible to detect individual fascicles in the ACL. PMID:25332942

  2. Computational Models of X-Ray Burst Quenching Times and 12C Nucleosynthesis Following a Superburst

    SciTech Connect

    Fisker, J L

    2009-03-19

    Superbursts are energetic events on neutron stars that are a thousand times more powerful than ordinary type I X-ray bursts. They are believed to be powered by a thermonuclear explosion of accumulated {sup 12}C. However, the source of this {sup 12}C remains elusive to theoretical calculations and its concentration and ignition depth are both unknown. Here we present the first computational simulations of the nucleosynthesis during the thermal decay of a superbust, where X-ray bursts are quenched. Our calculations of the quenching time verify previous analytical calculations and shed new light on the physics of stable burning at low accretion rates. We show that concentrated (X{sub {sup 12}C} {approx}> 0.40), although insufficient, amounts of {sup 12}C are generated during the several weeks following the superburst where the decaying thermal flux of the superburst stabilizes the burning of the accreted material.

  3. Microphase-contrast x-ray computed tomography for basic biomedical study at SPring-8

    NASA Astrophysics Data System (ADS)

    Wu, Jin; Takeda, Tohoru; Lwin, Thet-Thet; Koyama, Ichiro; Momose, Atsushi; Fujii, Akiko; Hamaishi, Yoshitaka; Kuroe, Taichi; Yuasa, Tetsuya; Suzuki, Yoshio; Akatsuka, Takao

    2004-10-01

    Micro-phase-contrast X-ray computed tomography with an X-ray interferometer (micro-phase-contrast CT) is in operation to obtain high spatial resolution images of less than 0.01 mm at the undulator beam-line 20XU of SPring-8, Japan, and we applied micro-phase-contrast CT to observe the organs of rats and hamsters. The excised kidney and spleen fixed by formalin were imaged. The fine inner-structures such as vessels, glomeruli of kidney and white and red pulps of spleen were visualized clearly about 0.01-mm spatial resolutions without using contrast agent or staining procedure. The results were very similar to those by optical microscopic images with 20-fold magnification. These results suggest that the micro-phase tomography might be a useful tool for various biomedical researches.

  4. Development of a Computer-Controlled Polishing Process for X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Arnold, William; Ramsey, Brian

    2009-01-01

    The future X-ray observatory missions require grazing-incidence x-ray optics with angular resolution of < 5 arcsec half-power diameter. The achievable resolution depends ultimately on the quality of polished mandrels from which the shells are replicated. With an aim to fabricate better shells, and reduce the cost/time of mandrel production, a computer-controlled polishing machine is developed for deterministic and localized polishing of mandrels. Cylindrical polishing software is also developed that predicts the surface residual errors under a given set of operating parameters and lap configuration. Design considerations of the polishing lap are discussed and the effects of nonconformance of the lap and the mandrel are presented.

  5. Heterogeneous computing for vertebra detection and segmentation in x-ray images.

    PubMed

    Lecron, Fabian; Mahmoudi, Sidi Ahmed; Benjelloun, Mohammed; Mahmoudi, Saïd; Manneback, Pierre

    2011-01-01

    The context of this work is related to the vertebra segmentation. The method we propose is based on the active shape model (ASM). An original approach taking advantage of the edge polygonal approximation was developed to locate the vertebra positions in a X-ray image. Despite the fact that segmentation results show good efficiency, the time is a key variable that has always to be optimized in a medical context. Therefore, we present how vertebra extraction can efficiently be performed in exploiting the full computing power of parallel (GPU) and heterogeneous (multi-CPU/multi-GPU) architectures. We propose a parallel hybrid implementation of the most intensive steps enabling to boost performance. Experimentations have been conducted using a set of high-resolution X-ray medical images, showing a global speedup ranging from 3 to 22, by comparison with the CPU implementation. Data transfer times between CPU and GPU memories were included in the execution times of our proposed implementation.

  6. Fluorescent X-Ray Computed Tomography towards Molecular Imaging: Proof-of-Concept Experiments

    SciTech Connect

    Yuasa, Tetsuya; Huo, Qingkai; Akatsuka, Takao; Takeda, Tohoru; Hyodo, Kazuyuki; Dilmanian, F. Avraham

    2009-03-10

    By means of fluorescent x-ray computed tomography (FXCT) one can detect and image a distribution of non-radioactive imaging agent, e.g., iodine, in a biomedical subject at a high spatial resolution, so it can be a novel molecular imaging modality. We have been studying an FXCT system using synchrotron radiation for in-vivo imaging brains of small animals such as mouse, or rat. For the purpose, we propose a fast FXCT imaging method based on the novel geometry. In this study, we prove the feasibility of this concept and investigate its imaging properties, including spatial and contrast resolutions and quantitativeness, by imaging an acrylic phantom and a normal mouse brain using a preliminary imaging system with monochromatic synchrotron x rays.

  7. Evaluation of a computer aided X-ray fluorographic system. Part 2: Image processing

    NASA Astrophysics Data System (ADS)

    Burch, S. F.; Cocking, S. J.

    1981-12-01

    The TV imagery from a computer aided X-ray fluorographic system has been digitally processed with an I2S model 70E image processor, controlled by a PDP 11/60 minicomputer. The image processor allowed valuable processing for detection of defects in cast components to be carried out at television frame rates. Summation of TV frames was used to reduce noise, and hence improve the thickness sensitivity of the system. A displaced differencing technique and interactive contrast enhancement were then used to improve the reliability of inspection by removing spurious blemishes and interferences lines, while simultaneously enhancing the visibility of real defects. The times required for these operations are given, and the benefits provided for X-ray fluorography are illustrated by the results from inspection of aero engine castings.

  8. Pseudomonoenergetic x-ray diffraction measurements using balanced filters for coherent-scatter computed tomography

    SciTech Connect

    Beath, S. R.; Cunningham, I. A.

    2009-05-15

    Coherent-scatter computed tomography (CSCT) is a method of ''composition'' imaging based on measurements of diffraction patterns from tissues. Use of an x-ray tube degrades scatter pattern angular resolution due to the x-ray spectral width, making it difficult to uniquely identify some materials. The use of two transmission filters with similar atomic numbers (balanced ''Ross filters'') to generate pseudomonoenergetic scatter patterns is described as it applies to CSCT. An analysis of angular-blur mechanisms reveals that focal spot size and beam width are the most important factors determining Bragg-peak width when Er-Tm filters are used. A relative RMS spectral width of 1% can be achieved in the difference spectrum and a Bragg-peak RMS angular width of approximately 0.14 deg. (relative width of 3% at 5 deg. scatter angle) can be achieved with an effective energy of 58 keV.

  9. X-ray refraction-contrast computed tomography images using dark-field imaging optics

    SciTech Connect

    Sunaguchi, Naoki; Yuasa, Tetsuya; Huo, Qingkai; Ichihara, Shu; Ando, Masami

    2010-10-11

    If an x-ray beam containing internal information derived from sample soft tissue is incident upon a Laue-case analyzer, the beam will subsequently split into a forwardly diffracted beam and a separate diffracted beam. Using these beams acquired simultaneously, a refraction-contrast computed tomography (CT) imaging system for biomedical use with lower radiation dose can be easily realized, and has a high depicting capability on the soft tissues compared with conventional x-ray CT based on absorption contrast principles. In this paper, we propose an imaging system using dark-field imaging for CT measurement based on a tandem system of Bragg- and Laue-case crystals with two two-dimensional detectors, along with a data-processing method to extract information on refraction from the measured entangled intensities by use of rocking curve fitting with polynomial functions. Reconstructed images of soft tissues are presented and described.

  10. Computational assessment of the impact of gamma-ray detector material properties on spectroscopic performance

    NASA Astrophysics Data System (ADS)

    Jordan, David V.; Baciak, James E.; McDonald, Benjamin S.; Hensley, Walter K.; Miller, Erin A.; Wittman, Richard S.; Siciliano, Edward R.

    2011-09-01

    Pacific Northwest National Laboratory (PNNL) is performing a computational assessment of the impact of several important gamma-ray detector material properties (e.g. energy resolution and intrinsic detection efficiency) on the scenario-specific spectroscopic performance of these materials. The research approach combines 3D radiation transport calculations, detector response modeling, and spectroscopic analysis of simulated energy deposition spectra to map the functional dependence of detection performance on the underlying material properties. This assessment is intended to help guide formulation of performance goals for new detector materials within the context of materials discovery programs, with an emphasis on applications in the threat reduction, nonproliferation, and safeguards/ verification user communities. The research results will also provide guidance to the gamma-ray sensor design community in estimating relative spectroscopic performance merits of candidate materials for novel or notional detectors.

  11. Multiple energy computed tomography with monochromatic x rays from the NSLS

    SciTech Connect

    Dilmanian, F.A.; Nachaliel, E.; Garrett, R.F.; Thomlinson, W.C.; Chapman, L.D.; Moulin, H.R.; Oversluizen, T.; Rarback, H.M.; Rivers, M.; Spanne, P.; Thompson, A.C.; Zeman, H.D.

    1991-12-31

    We used monochromatic x rays from the X17 superconducting wiggler beamline at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory, for dual-energy quantitative computed tomography (CT) of a 27 mm-diameter phantom containing solutions of different KOH concentrations in cylindrical holes of 5-mm diameter. The CT configuration was a fixed horizontal fan-shaped beam of 1.5 mm height and 30 mm width, and a subject rotating around a vertical axis. The transmitted x rays were detected by a linear-array Si(Li) detector with 120 elements of 0.25 mm width each. We used a two-crystal Bragg-Bragg fixed-exit monochromator with Si<220> crystals. Dual photon absorptiometry (DPA) CT data were taken at 20 and 38 keV. The reconstructed phantom images show the potential of the system for quantitative CT.

  12. Anatomical evaluation of hepatic vascular system in healthy beagles using X-ray contrast computed tomography.

    PubMed

    Oishi, Yasuhisa; Tani, Kenji; Nakazawa, Hiroshi; Itamoto, Kazuhito; Haraguchi, Tomoya; Taura, Yasuho

    2015-08-01

    Liver contrast X-ray computed tomography (CT) has been used for evaluation of hepatic vessels for liver transplantation, liver lobectomy, interventional radiology and diagnosis of hepatocellular carcinoma in humans. However, there remains scant available anatomical information on normal hepatic vessels in the veterinary field. In this study, visualization of hepatic vessels was evaluated in 32 normal beagle dogs by X-ray contrast CT using triple phase images. The following hepatic vessels were clearly visualized: arterial, portal and hepatic veins. With regards to the running patterns of the portal vein and hepatic vein, there were no significant differences between the dogs. However, the hepatic artery exhibited some differences in each dog. In particular, the hepatic artery of the quadrate lobe and the right lateral lobe had many running patterns. The results of the present study could be useful for veterinary diagnosis, surgery and interventional radiology. PMID:25843113

  13. Experimental validation of a kilovoltage x-ray source model for computing imaging dose

    SciTech Connect

    Poirier, Yannick; Kouznetsov, Alexei; Koger, Brandon; Tambasco, Mauro

    2014-04-15

    Purpose: To introduce and validate a kilovoltage (kV) x-ray source model and characterization method to compute absorbed dose accrued from kV x-rays. Methods: The authors propose a simplified virtual point source model and characterization method for a kV x-ray source. The source is modeled by: (1) characterizing the spatial spectral and fluence distributions of the photons at a plane at the isocenter, and (2) creating a virtual point source from which photons are generated to yield the derived spatial spectral and fluence distribution at isocenter of an imaging system. The spatial photon distribution is determined by in-air relative dose measurements along the transverse (x) and radial (y) directions. The spectrum is characterized using transverse axis half-value layer measurements and the nominal peak potential (kVp). This source modeling approach is used to characterize a Varian{sup ®} on-board-imager (OBI{sup ®}) for four default cone-beam CT beam qualities: beams using a half bowtie filter (HBT) with 110 and 125 kVp, and a full bowtie filter (FBT) with 100 and 125 kVp. The source model and characterization method was validated by comparing dose computed by the authors’ inhouse software (kVDoseCalc) to relative dose measurements in a homogeneous and a heterogeneous block phantom comprised of tissue, bone, and lung-equivalent materials. Results: The characterized beam qualities and spatial photon distributions are comparable to reported values in the literature. Agreement between computed and measured percent depth-dose curves is ⩽2% in the homogeneous block phantom and ⩽2.5% in the heterogeneous block phantom. Transverse axis profiles taken at depths of 2 and 6 cm in the homogeneous block phantom show an agreement within 4%. All transverse axis dose profiles in water, in bone, and lung-equivalent materials for beams using a HBT, have an agreement within 5%. Measured profiles of FBT beams in bone and lung-equivalent materials were higher than their

  14. Feasibility study of endoscopic x-ray luminescence computed tomography: Simulation demonstration and phantom application

    SciTech Connect

    Chen, Xueli; Liang, Jimin; Cao, Xin; Yang, Defu; Chen, Dongmei; Ripoll, Jorge; Tian, Jie

    2013-08-28

    Even though endoscopic fluorescence diffuse optical tomography (eFDOT) exhibits significant potential, currently its application is limited due to the existence of strong autofluorescence and the imaging inaccuracy caused by a very short source-detector distance. Motivated by the emerging X-ray luminescence computed tomography (XLCT) technology, we presented an endoscopic XLCT (eXLCT) methodology. In the methodology, the aperture angle of the objective was incorporated into the forward model, providing a more accurate description of light propagation. Numerical simulation with a heterogeneous geometry and an imaging experiment with a physical phantom were illustrated to demonstrate the feasibility of the presented eXLCT methodology.

  15. Development of Computer Tomography System for the Soft X-ray Microscope at Ritsumeikan University

    SciTech Connect

    Ohigashi, T.; Fujii, H.; Usui, K.; Namba, H.; Mizutani, H.; Takemoto, K.; Kihara, H.

    2011-09-09

    A synchrotron-based full-field imaging soft x-ray microscope was tuned appropriately to perform computer tomography. The contrast and focal depth of the optical system were evaluated by using a Fresnel zone plate as a test object of variable spatial frequency. A focal depth of 15 {mu}m was obtained at the spatial frequency of 4.3 {mu}m{sup -1} according to Rayleigh's criterion. As a first trial of three-dimensional observation using this system, the cerebral cortex of the brain of a mouse, trimmed to a columnar shape by focused ion beam milling, was studied using a wavelength of 1.87-nm.

  16. Mechanisms of Porphyroblast Crystallization: Results from High-Resolution Computed X-ray Tomography.

    PubMed

    Carlson, W D; Denison, C

    1992-08-28

    Quantitative three-dimensional analysis of rock textures is now possible with the use of high-resolution computed x-ray tomography. When applied to metamorphic rocks, this technique provides data on the sizes and positions of minerals that allow mechanisms of porphyroblast crystallization to be identified. Statistical analysis of the sizes and spatial disposition of thousands of garnet crystals in three regionally metamorphosed rocks with diverse mineralogies, in conjunction with simple numerical models for crystallization, reveals in all cases the dominance of crystallization mechanisms whose kinetics are governed by rates of intergranular diffusion of nutrients. PMID:17742755

  17. NDE x-ray computed tomography applications research. Final report, August 1989-September 1994

    SciTech Connect

    Neel, S.T.; Yancey, R.N.; Eliasen, D.S.; Phillips, D.H.

    1994-11-01

    This report summarizes research efforts in X-ray computed tomography at Wright Laboratory. Attention is focused on applications development efforts that have been successful in coupling CT with engineering functions to provide new insight to materials and processing issues in a cost effective manner. A sampling of the myriad of applications to be covered in this report includes: tracking of densification during the processing of composite materials and ceramics, measuring the thickness of internal walls in castings, failure analysis of an aircraft landing gear actuator, and verification of modeling damage zones in slug impacted fiberglass armor. Extrapolation of specific studies to broader horizons are offered.

  18. Mechanisms of Porphyroblast Crystallization: Results from High-Resolution Computed X-ray Tomography.

    PubMed

    Carlson, W D; Denison, C

    1992-08-28

    Quantitative three-dimensional analysis of rock textures is now possible with the use of high-resolution computed x-ray tomography. When applied to metamorphic rocks, this technique provides data on the sizes and positions of minerals that allow mechanisms of porphyroblast crystallization to be identified. Statistical analysis of the sizes and spatial disposition of thousands of garnet crystals in three regionally metamorphosed rocks with diverse mineralogies, in conjunction with simple numerical models for crystallization, reveals in all cases the dominance of crystallization mechanisms whose kinetics are governed by rates of intergranular diffusion of nutrients.

  19. Numerical ray-tracing approach with laser intensity distribution for LIDAR signal power function computation

    NASA Astrophysics Data System (ADS)

    Shi, Guangyuan; Li, Song; Huang, Ke; Li, Zile; Zheng, Guoxing

    2016-10-01

    We have developed a new numerical ray-tracing approach for LIDAR signal power function computation, in which the light round-trip propagation is analyzed by geometrical optics and a simple experiment is employed to acquire the laser intensity distribution. It is relatively more accurate and flexible than previous methods. We emphatically discuss the relationship between the inclined angle and the dynamic range of detector output signal in biaxial LIDAR system. Results indicate that an appropriate negative angle can compress the signal dynamic range. This technique has been successfully proved by comparison with real measurements.

  20. Numerical ray-tracing approach with laser intensity distribution for LIDAR signal power function computation

    NASA Astrophysics Data System (ADS)

    Shi, Guangyuan; Li, Song; Huang, Ke; Li, Zile; Zheng, Guoxing

    2016-08-01

    We have developed a new numerical ray-tracing approach for LIDAR signal power function computation, in which the light round-trip propagation is analyzed by geometrical optics and a simple experiment is employed to acquire the laser intensity distribution. It is relatively more accurate and flexible than previous methods. We emphatically discuss the relationship between the inclined angle and the dynamic range of detector output signal in biaxial LIDAR system. Results indicate that an appropriate negative angle can compress the signal dynamic range. This technique has been successfully proved by comparison with real measurements.

  1. Assessment of asthmatic inflammation using hybrid fluorescence molecular tomography-x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Ma, Xiaopeng; Prakash, Jaya; Ruscitti, Francesca; Glasl, Sarah; Stellari, Fabio Franco; Villetti, Gino; Ntziachristos, Vasilis

    2016-01-01

    Nuclear imaging plays a critical role in asthma research but is limited in its readings of biology due to the short-lived signals of radio-isotopes. We employed hybrid fluorescence molecular tomography (FMT) and x-ray computed tomography (XCT) for the assessment of asthmatic inflammation based on resolving cathepsin activity and matrix metalloproteinase activity in dust mite, ragweed, and Aspergillus species-challenged mice. The reconstructed multimodal fluorescence distribution showed good correspondence with ex vivo cryosection images and histological images, confirming FMT-XCT as an interesting alternative for asthma research.

  2. Development of Computer Tomography System for the Soft X-ray Microscope at Ritsumeikan University

    NASA Astrophysics Data System (ADS)

    Ohigashi, T.; Fujii, H.; Usui, K.; Namba, H.; Mizutani, H.; Takemoto, K.; Kihara, H.

    2011-09-01

    A synchrotron-based full-field imaging soft x-ray microscope was tuned appropriately to perform computer tomography. The contrast and focal depth of the optical system were evaluated by using a Fresnel zone plate as a test object of variable spatial frequency. A focal depth of 15 μm was obtained at the spatial frequency of 4.3 μm-1 according to Rayleigh's criterion. As a first trial of three-dimensional observation using this system, the cerebral cortex of the brain of a mouse, trimmed to a columnar shape by focused ion beam milling, was studied using a wavelength of 1.87-nm.

  3. The Effect of Experimental Variables on Industrial X-Ray Micro-Computed Sensitivity

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Rauser, Richard W.

    2014-01-01

    A study was performed on the effect of experimental variables on radiographic sensitivity (image quality) in x-ray micro-computed tomography images for a high density thin wall metallic cylinder containing micro-EDM holes. Image quality was evaluated in terms of signal-to-noise ratio, flaw detectability, and feature sharpness. The variables included: day-to-day reproducibility, current, integration time, voltage, filtering, number of frame averages, number of projection views, beam width, effective object radius, binning, orientation of sample, acquisition angle range (180deg to 360deg), and directional versus transmission tube.

  4. Image recovery techniques for x-ray computed tomography in limited data environments

    SciTech Connect

    Aufderheide, M B; Goodman, D M; Jackson, J A; Johansson, E M

    1999-03-01

    There is an increasing requirement throughout LLNL for nondestructive evaluation using X-ray computed tomography (CT). In many cases, restrictions on data acquisition time, imaging geometry, and budgets make it unfeasible to acquire projection data over enough views to achieve desired spatial resolution using conventional CT methods. In particular, conventional CT methods are non-iterative algorithms that have the advantage of low computational effort, but they are not sufficiently adaptable to incorporate prior information or non-Gaussian statistics. Most currently existing iterative tomography algorithms are based on methods that are time consuming because they converge very flowingly, if at all. The goal of the work was to develop a set of limited data CT reconstruction tools and then demonstrate their usefulness by applying them to a variety of problems of interest to LLNL. In this project they continued their development of reconstruction tools and they have demonstrated their effectiveness on several important problems.

  5. SIGI: Field Test and Evaluation of a Computer-Based System of Interactive Guidance and Information. Summary of Final Report.

    ERIC Educational Resources Information Center

    Chapman, Warren; And Others

    The computer-based System of Interactive Guidance and Information (SIGI) was field tested and evaluated at five community colleges and one university. Developed by Educational Testing Service, SIGI assists students in the process of informed and rational career decision making. Interacting at a cathode-ray tube terminal with a computer, students…

  6. SIGI: Field Test and Evaluation of a Computer-Based System of Interactive Guidance and Information. Volume I: Report.

    ERIC Educational Resources Information Center

    Chapman, Warren; And Others

    The computer-based System of Interactive Guidance and Information (SIGI) was field tested and evaluated at five community colleges and one university. Developed by Educational Testing Service, SIGI assists students in the process of informed and rational career decision making. Interacting at a cathode-ray tube terminal with a computer, students…

  7. Calibration-free quantification of interior properties of porous media with x-ray computed tomography.

    PubMed

    Hussein, Esam M A; Agbogun, H M D; Al, Tom A

    2015-03-01

    A method is presented for interpreting the values of x-ray attenuation coefficients reconstructed in computed tomography of porous media, while overcoming the ambiguity caused by the multichromatic nature of x-rays, dilution by void, and material heterogeneity. The method enables determination of porosity without relying on calibration or image segmentation or thresholding to discriminate pores from solid material. It distinguishes between solution-accessible and inaccessible pores, and provides the spatial and frequency distributions of solid-matrix material in a heterogeneous medium. This is accomplished by matching an image of a sample saturated with a contrast solution with that saturated with a transparent solution. Voxels occupied with solid-material and inaccessible pores are identified by the fact that they maintain the same location and image attributes in both images, with voxels containing inaccessible pores appearing empty in both images. Fully porous and accessible voxels exhibit the maximum contrast, while the rest are porous voxels containing mixtures of pore solutions and solid. This matching process is performed with an image registration computer code, and image processing software that requires only simple subtraction and multiplication (scaling) processes. The process is demonstrated in dolomite (non-uniform void distribution, homogeneous solid matrix) and sandstone (nearly uniform void distribution, heterogeneous solid matrix) samples, and its overall performance is shown to compare favorably with a method based on calibration and thresholding. PMID:25576734

  8. Microstructural analysis using X-ray computed tomography (CT) in flax/epoxy composites

    NASA Astrophysics Data System (ADS)

    Kersani, M.; Lomov, SV; Van Vuure, AW; Bouabdallah, A.; Verpoest, I.

    2016-07-01

    Among natural fibres which have recently become attractive to researchers, flax is probably the most commonly used bast-type fibre today. Due to its properties and availability, flax fibre has potential to substitute glass in polymer composites. A flax fibre has a complex structure; it can be classified into elementary fibres, which are grouped into so-called technical fibres. These technical fibres themselves are actually composite structures. Several works [1, 2, 3] were focussed on the study of damage behaviour in unidirectional flax fibres reinforced composites, where materials were subjected to tensile loading. At the microscopic level and at low stress, microcracks arise within the material and by growing they may lead to other forms of damage such as delamination, fibre breakage, interfacial debonding...etc. In order to better understand the damage phenomena and to better control the parameters which lead to the failure, several methods and techniques have been developed on natural fibre reinforced composites [2, 3]. In the present work, X-ray computed tomography (CT) technique has been used to observe damage in flax/epoxy quasi-unidirectional woven laminates, loaded in uniaxial tension. The tensile tests show that these composites offer good mechanical properties. X-ray computed tomography technique allowed us, on the one hand to determine the microstructure parameters of the studied composites and to observe the damage occurring during loading, on the other. The inspection of the several tomography images showed cracks on interface of the yarns and technical fibres.

  9. A reference workpiece for voxel size correction in x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Lifton, Joseph J.; Cross, Kevin J.; Malcolm, Andrew A.; McBride, John W.

    2013-06-01

    X-ray computed tomography (CT) is increasingly used for dimensional metrology, allowing the inspection of both interior and exterior features impossible to observe using traditional optical and tactile measurement techniques. X-ray CT offers many benefits over traditional instruments as a visual inspection tool, however, extracting dimensional information from the reconstructed data-sets must be approached with caution due to error sources that can propagate through the image reconstruction processes. One error source originates from values of the source-to-object and source-to-detector distances; these are critical inputs as they define the voxel size, a global scalar directly influencing all dimensions extracted from the data. To reduce voxel size errors a reference workpiece can be scanned using the same measurement settings as the actual workpiece. By reconstructing the reference workpiece a reference dimension can be evaluated and this then used to adjust the voxel size of the actual workpiece. This reference dimension must be threshold independent, namely it is determined without the influence of edge detection thresholds. This paper offers a reference workpiece designed for measurement in an X-ray CT system, a coordinate measuring machine (CMM), and an optical profiler. Repeated measurements are made of the reference workpiece using all three instruments and

  10. X-ray computed tomography of wood-adhesive bondlines: Attenuation and phase-contrast effects

    DOE PAGES

    Paris, Jesse L.; Kamke, Frederick A.; Xiao, Xianghui

    2015-07-29

    Microscale X-ray computed tomography (XCT) is discussed as a technique for identifying 3D adhesive distribution in wood-adhesive bondlines. Visualization and material segmentation of the adhesives from the surrounding cellular structures require sufficient gray-scale contrast in the reconstructed XCT data. Commercial wood-adhesive polymers have similar chemical characteristics and density to wood cell wall polymers and therefore do not provide good XCT attenuation contrast in their native form. Here, three different adhesive types, namely phenol formaldehyde, polymeric diphenylmethane diisocyanate, and a hybrid polyvinyl acetate, are tagged with iodine such that they yield sufficient X-ray attenuation contrast. However, phase-contrast effects at material edgesmore » complicate image quality and segmentation in XCT data reconstructed with conventional filtered backprojection absorption contrast algorithms. A quantitative phase retrieval algorithm, which isolates and removes the phase-contrast effect, was demonstrated. The paper discusses and illustrates the balance between material X-ray attenuation and phase-contrast effects in all quantitative XCT analyses of wood-adhesive bondlines.« less

  11. X-ray computed tomography of wood-adhesive bondlines: Attenuation and phase-contrast effects

    SciTech Connect

    Paris, Jesse L.; Kamke, Frederick A.; Xiao, Xianghui

    2015-07-29

    Microscale X-ray computed tomography (XCT) is discussed as a technique for identifying 3D adhesive distribution in wood-adhesive bondlines. Visualization and material segmentation of the adhesives from the surrounding cellular structures require sufficient gray-scale contrast in the reconstructed XCT data. Commercial wood-adhesive polymers have similar chemical characteristics and density to wood cell wall polymers and therefore do not provide good XCT attenuation contrast in their native form. Here, three different adhesive types, namely phenol formaldehyde, polymeric diphenylmethane diisocyanate, and a hybrid polyvinyl acetate, are tagged with iodine such that they yield sufficient X-ray attenuation contrast. However, phase-contrast effects at material edges complicate image quality and segmentation in XCT data reconstructed with conventional filtered backprojection absorption contrast algorithms. A quantitative phase retrieval algorithm, which isolates and removes the phase-contrast effect, was demonstrated. The paper discusses and illustrates the balance between material X-ray attenuation and phase-contrast effects in all quantitative XCT analyses of wood-adhesive bondlines.

  12. Reverse projection retrieval in edge illumination x-ray phase contrast computed tomography

    NASA Astrophysics Data System (ADS)

    Hagen, Charlotte K.; Endrizzi, Marco; Diemoz, Paul C.; Olivo, Alessandro

    2016-06-01

    Edge illumination (EI) x-ray phase contrast computed tomography (CT) can provide three-dimensional distributions of the real and imaginary parts of the complex refractive index (n=1-δ +\\text{i}β ) of the sample. Phase retrieval, i.e. the separation of attenuation and refraction data from projections that contain a combination of both, is a key step in the image reconstruction process. In EI-based x-ray phase contrast CT, this is conventionally performed on the basis of two projections acquired in opposite illumination configurations (i.e. with different positions of the pre-sample mask) at each CT angle. Displacing the pre-sample mask at each projection makes the scan susceptible to motor-induced misalignment and prevents a continuous sample rotation. We present an alternative method for the retrieval of attenuation and refraction data that does not require repositioning the pre-sample mask. The method is based on the reverse projection relation published by Zhu et al (2010 Proc. Natl Acad. Sci. USA 107 13576–81) for grating interferometry-based x-ray phase contrast CT. We use this relation to derive a simplified acquisition strategy that allows acquiring data with a continuous sample rotation, which can reduce scan time when combined with a fast read-out detector. Besides discussing the theory and the necessary alignment of the experimental setup, we present tomograms obtained with reverse projection retrieval and demonstrate their agreement with those obtained with the conventional EI retrieval.

  13. Reverse projection retrieval in edge illumination x-ray phase contrast computed tomography

    NASA Astrophysics Data System (ADS)

    Hagen, Charlotte K.; Endrizzi, Marco; Diemoz, Paul C.; Olivo, Alessandro

    2016-06-01

    Edge illumination (EI) x-ray phase contrast computed tomography (CT) can provide three-dimensional distributions of the real and imaginary parts of the complex refractive index (n=1-δ +\\text{i}β ) of the sample. Phase retrieval, i.e. the separation of attenuation and refraction data from projections that contain a combination of both, is a key step in the image reconstruction process. In EI-based x-ray phase contrast CT, this is conventionally performed on the basis of two projections acquired in opposite illumination configurations (i.e. with different positions of the pre-sample mask) at each CT angle. Displacing the pre-sample mask at each projection makes the scan susceptible to motor-induced misalignment and prevents a continuous sample rotation. We present an alternative method for the retrieval of attenuation and refraction data that does not require repositioning the pre-sample mask. The method is based on the reverse projection relation published by Zhu et al (2010 Proc. Natl Acad. Sci. USA 107 13576-81) for grating interferometry-based x-ray phase contrast CT. We use this relation to derive a simplified acquisition strategy that allows acquiring data with a continuous sample rotation, which can reduce scan time when combined with a fast read-out detector. Besides discussing the theory and the necessary alignment of the experimental setup, we present tomograms obtained with reverse projection retrieval and demonstrate their agreement with those obtained with the conventional EI retrieval.

  14. Grating-based X-ray Dark-field Computed Tomography of Living Mice

    PubMed Central

    Velroyen, A.; Yaroshenko, A.; Hahn, D.; Fehringer, A.; Tapfer, A.; Müller, M.; Noël, P.B.; Pauwels, B.; Sasov, A.; Yildirim, A.Ö.; Eickelberg, O.; Hellbach, K.; Auweter, S.D.; Meinel, F.G.; Reiser, M.F.; Bech, M.; Pfeiffer, F.

    2015-01-01

    Changes in x-ray attenuating tissue caused by lung disorders like emphysema or fibrosis are subtle and thus only resolved by high-resolution computed tomography (CT). The structural reorganization, however, is of strong influence for lung function. Dark-field CT (DFCT), based on small-angle scattering of x-rays, reveals such structural changes even at resolutions coarser than the pulmonary network and thus provides access to their anatomical distribution. In this proof-of-concept study we present x-ray in vivo DFCTs of lungs of a healthy, an emphysematous and a fibrotic mouse. The tomographies show excellent depiction of the distribution of structural – and thus indirectly functional – changes in lung parenchyma, on single-modality slices in dark field as well as on multimodal fusion images. Therefore, we anticipate numerous applications of DFCT in diagnostic lung imaging. We introduce a scatter-based Hounsfield Unit (sHU) scale to facilitate comparability of scans. In this newly defined sHU scale, the pathophysiological changes by emphysema and fibrosis cause a shift towards lower numbers, compared to healthy lung tissue. PMID:26629545

  15. Cathodes - Technological review

    SciTech Connect

    Cherkouk, Charaf; Nestler, Tina

    2014-06-16

    Lithium cobalt oxide (LiCoO{sub 2}) was already used in the first commercialized Li-ion battery by SONY in 1990. Still, it is the most frequently used cathode material nowadays. However, LiCoO{sub 2} is intrinsically unstable in the charged state, especially at elevated temperatures and in the overcharged state causing volume changes and transport limitation for high power batteries. In this paper, some technological aspects with large impact on cell performance from the cathode material point of view will be reviewed. At first it will be focused on the degradation processes and life-time mechanisms of the cathode material LiCoO{sub 2}. Electrochemical and structural results on commercial Li-ion batteries recorded during the cycling will be discussed. Thereafter, advanced nanomaterials for new cathode materials will be presented.

  16. X-ray Streak Camera Cathode Development and Timing Accuracy of the 4w UV Fiducial System at the National Ignition Facility

    SciTech Connect

    Opachich, Y P; Palmer, N; Homoelle, D; Hatch, B W; Bell, P; Bradley, D; Kalantar, D; Browning, D; Landen, O

    2012-05-02

    The convergent ablator experiments at the National Ignition Facility (NIF) are designed to measure the peak velocity and remaining ablator mass of an indirectly driven imploding capsule. Such a measurement can be performed using an x-ray source to backlight the capsule and an x-ray streak camera to record the capsule as it implodes. The ultimate goal of this experiment is to achieve an accuracy of 2% in the velocity measurement, which translates to a {+-}2 ps temporal accuracy over any 300 ps interval for the streak camera. In order to achieve this, a 4-{omega} (263nm) temporal fiducial system has been implemented for the x-ray streak camera at NIF. Aluminum, Titanium, Gold and Silver photocathode materials have been tested. Aluminum showed the highest quantum efficiency, with five times more peak signal counts per fiducial pulse when compared to Gold. The fiducial pulse data was analyzed to determine the centroiding a statistical accuracy for incident laser pulse energies of 1 and 10 nJ, showing an accuracy of {+-}1.6 ps and {+-}0.7 ps respectively.

  17. X-Ray Computed Tomography Inspection of the Stardust Heat Shield

    NASA Technical Reports Server (NTRS)

    McNamara, Karen M.; Schneberk, Daniel J.; Empey, Daniel M.; Koshti, Ajay; Pugel, D. Elizabeth; Cozmuta, Ioana; Stackpoole, Mairead; Ruffino, Norman P.; Pompa, Eddie C.; Oliveras, Ovidio; Kontinos, Dean A.

    2010-01-01

    The "Stardust" heat shield, composed of a PICA (Phenolic Impregnated Carbon Ablator) Thermal Protection System (TPS), bonded to a composite aeroshell, contains important features which chronicle its time in space as well as re-entry. To guide the further study of the Stardust heat shield, NASA reviewed a number of techniques for inspection of the article. The goals of the inspection were: 1) to establish the material characteristics of the shield and shield components, 2) record the dimensions of shield components and assembly as compared with the pre-flight condition, 3) provide flight infonnation for validation and verification of the FIAT ablation code and PICA material property model and 4) through the evaluation of the shield material provide input to future missions which employ similar materials. Industrial X-Ray Computed Tomography (CT) is a 3D inspection technology which can provide infonnation on material integrity, material properties (density) and dimensional measurements of the heat shield components. Computed tomographic volumetric inspections can generate a dimensionally correct, quantitatively accurate volume of the shield assembly. Because of the capabilities offered by X-ray CT, NASA chose to use this method to evaluate the Stardust heat shield. Personnel at NASA Johnson Space Center (JSC) and Lawrence Livermore National Labs (LLNL) recently performed a full scan of the Stardust heat shield using a newly installed X-ray CT system at JSC. This paper briefly discusses the technology used and then presents the following results: 1. CT scans derived dimensions and their comparisons with as-built dimensions anchored with data obtained from samples cut from the heat shield; 2. Measured density variation, char layer thickness, recession and bond line (the adhesive layer between the PICA and the aeroshell) integrity; 3. FIAT predicted recession, density and char layer profiles as well as bondline temperatures Finally suggestions are made as to future uses

  18. Gamma-ray spectrometry data collection and reduction by simple computing systems.

    PubMed

    Op de Beeck, J

    1975-12-01

    The review summarizes the present state of the involvement of relatively small computing devices in the collection and processing of gamma-ray spectrum data. An economic and utilitarian point of view has been chosen with regard to data collection in order to arrive at practically valuable conclusions in terms of feasibility of possible configurations with respect to their eventual application. A unified point of view has been adopted with regard to data processing by developing an information theoretical approach on a more or less intuitive level in an attempt to remove the largest part of the virtual disparity between the several processing methods described in the literature. A synoptical introduction to the most important mathematical methods has been incorporated, together with a detailed theoretical description of the concept gamma-ray spectrum. In accordance with modern requirements, the discussions are mainly oriented towards high-resolution semiconductor detector-type spectra. The critical evaluation of the processing methods reviewed is done with respect to a set of predefined criteria. Smoothing, peak detection, peak intensity determination, overlapping peak resolving and detection and upper limits are discussed in great detail. A preferred spectrum analysis method combining powerful data reduction properties with extreme simplicity and speed of operation is suggested. The general discussion is heavily oriented towards activation analysis application, but other disciplines making use of gamma-ray spectrometry will find the material presented equally useful. Final conclusions are given pointing to future developments and shifting their centre of gravity towards improving the quality of the measurements rather than expanding the use of tedious and sophisticated mathematical techniques requiring the limits of available computational power.

  19. Laboratory manual: mineral X-ray diffraction data retrieval/plot computer program

    USGS Publications Warehouse

    Hauff, Phoebe L.; VanTrump, George

    1976-01-01

    The Mineral X-Ray Diffraction Data Retrieval/Plot Computer Program--XRDPLT (VanTrump and Hauff, 1976a) is used to retrieve and plot mineral X-ray diffraction data. The program operates on a file of mineral powder diffraction data (VanTrump and Hauff, 1976b) which contains two-theta or 'd' values, and intensities, chemical formula, mineral name, identification number, and mineral group code. XRDPLT is a machine-independent Fortran program which operates in time-sharing mode on a DEC System i0 computer and the Gerber plotter (Evenden, 1974). The program prompts the user to respond from a time-sharing terminal in a conversational format with the required input information. The program offers two major options: retrieval only; retrieval and plot. The first option retrieves mineral names, formulas, and groups from the file by identification number, by the mineral group code (a classification by chemistry or structure), or by searches based on the formula components. For example, it enables the user to search for minerals by major groups (i.e., feldspars, micas, amphiboles, oxides, phosphates, carbonates) by elemental composition (i.e., Fe, Cu, AI, Zn), or by a combination of these (i.e., all copper-bearing arsenates). The second option retrieves as the first, but also plots the retrieved 2-theta and intensity values as diagrammatic X-ray powder patterns on mylar sheets or overlays. These plots can be made using scale combinations compatible with chart recorder diffractograms and 114.59 mm powder camera films. The overlays are then used to separate or sieve out unrelated minerals until unknowns are matched and identified.

  20. Utilisation of X-Ray computed microtomography for evaluation of iron sulphide distribution in roofing slate

    NASA Astrophysics Data System (ADS)

    Souček, Kamil; Daněk, Tomáš; Vavro, Martin; Botula, Jiří

    2016-04-01

    Roofing slate represents a traditional natural stone used for centuries for roofing and other construction applications in various types of buildings. Quality roofing slate must be primarily splittable into large, thin and waterproof tiles. In addition, it must be stable in colour and resistant against weathering. The abundance of mineral phases that weather easily or minerals that are long-term unstable has the effect of reducing the durability of slates in exterior conditions. One of the most problematic rock components, which are in a larger or smaller extent present in almost all slates, are iron sulphides, such as pyrite, marcasite or pyrrhotite. Under common atmospheric conditions, these minerals tend to oxidise, which leads to the formation of limonite and sulphuric acid. As a consequence of the origin of red-brown Fe oxyhydroxides, the undesirable colour changes of the slate may occur. But the most serious problem which occurs during this process is the changes in volume. This can cause disintegration of slate depending on the form of the iron sulphide occurrence. The content and size distribution of iron sulphides in roofing slate is normally determined using the microscopic analysis in transmitted light, combined with the observation in reflected light. For quantitative determination of iron sulphides in slate, the X-Ray powder diffraction is also often used. The results of the microscopic and X-Ray analyses need to be mutually compared and should not differ fundamentally. This paper is focused on the assessing the possibility of application of the X-Ray computed microtomography (CT) as a new complementary technique enabling the analysis of content and size (volume) distribution of iron sulphides in roofing slate. The X-Ray CT study was conducted using an XT H 225 ST industrial micro-tomographic system made by Nikon Metrology NV. Studied samples were reconstructed using the CT Pro 3D software (Nikon Metrology NV). The visualisation and analysis software

  1. Arcjet Cathode Phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  2. Arcjet cathode phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  3. 3D printing of preclinical X-ray computed tomographic data sets.

    PubMed

    Doney, Evan; Krumdick, Lauren A; Diener, Justin M; Wathen, Connor A; Chapman, Sarah E; Stamile, Brian; Scott, Jeremiah E; Ravosa, Matthew J; Van Avermaete, Tony; Leevy, W Matthew

    2013-01-01

    Three-dimensional printing allows for the production of highly detailed objects through a process known as additive manufacturing. Traditional, mold-injection methods to create models or parts have several limitations, the most important of which is a difficulty in making highly complex products in a timely, cost-effective manner.(1) However, gradual improvements in three-dimensional printing technology have resulted in both high-end and economy instruments that are now available for the facile production of customized models.(2) These printers have the ability to extrude high-resolution objects with enough detail to accurately represent in vivo images generated from a preclinical X-ray CT scanner. With proper data collection, surface rendering, and stereolithographic editing, it is now possible and inexpensive to rapidly produce detailed skeletal and soft tissue structures from X-ray CT data. Even in the early stages of development, the anatomical models produced by three-dimensional printing appeal to both educators and researchers who can utilize the technology to improve visualization proficiency. (3, 4) The real benefits of this method result from the tangible experience a researcher can have with data that cannot be adequately conveyed through a computer screen. The translation of pre-clinical 3D data to a physical object that is an exact copy of the test subject is a powerful tool for visualization and communication, especially for relating imaging research to students, or those in other fields. Here, we provide a detailed method for printing plastic models of bone and organ structures derived from X-ray CT scans utilizing an Albira X-ray CT system in conjunction with PMOD, ImageJ, Meshlab, Netfabb, and ReplicatorG software packages. PMID:23542702

  4. 3D printing of preclinical X-ray computed tomographic data sets.

    PubMed

    Doney, Evan; Krumdick, Lauren A; Diener, Justin M; Wathen, Connor A; Chapman, Sarah E; Stamile, Brian; Scott, Jeremiah E; Ravosa, Matthew J; Van Avermaete, Tony; Leevy, W Matthew

    2013-03-22

    Three-dimensional printing allows for the production of highly detailed objects through a process known as additive manufacturing. Traditional, mold-injection methods to create models or parts have several limitations, the most important of which is a difficulty in making highly complex products in a timely, cost-effective manner.(1) However, gradual improvements in three-dimensional printing technology have resulted in both high-end and economy instruments that are now available for the facile production of customized models.(2) These printers have the ability to extrude high-resolution objects with enough detail to accurately represent in vivo images generated from a preclinical X-ray CT scanner. With proper data collection, surface rendering, and stereolithographic editing, it is now possible and inexpensive to rapidly produce detailed skeletal and soft tissue structures from X-ray CT data. Even in the early stages of development, the anatomical models produced by three-dimensional printing appeal to both educators and researchers who can utilize the technology to improve visualization proficiency. (3, 4) The real benefits of this method result from the tangible experience a researcher can have with data that cannot be adequately conveyed through a computer screen. The translation of pre-clinical 3D data to a physical object that is an exact copy of the test subject is a powerful tool for visualization and communication, especially for relating imaging research to students, or those in other fields. Here, we provide a detailed method for printing plastic models of bone and organ structures derived from X-ray CT scans utilizing an Albira X-ray CT system in conjunction with PMOD, ImageJ, Meshlab, Netfabb, and ReplicatorG software packages.

  5. Experimental demonstration of novel imaging geometries for x-ray fluorescence computed tomography

    PubMed Central

    Fu, Geng; Meng, Ling-Jian; Eng, Peter; Newville, Matt; Vargas, Phillip; Riviere, Patrick La

    2013-01-01

    Purpose: X-ray fluorescence computed tomography (XFCT) is an emerging imaging modality that maps the three-dimensional distribution of elements, generally metals, in ex vivo specimens and potentially in living animals and humans. At present, it is generally performed at synchrotrons, taking advantage of the high flux of monochromatic x rays, but recent work has demonstrated the feasibility of using laboratory-based x-ray tube sources. In this paper, the authors report the development and experimental implementation of two novel imaging geometries for mapping of trace metals in biological samples with ∼50–500 μm spatial resolution. Methods: One of the new imaging approaches involves illuminating and scanning a single slice of the object and imaging each slice's x-ray fluorescent emissions using a position-sensitive detector and a pinhole collimator. The other involves illuminating a single line through the object and imaging the emissions using a position-sensitive detector and a slit collimator. They have implemented both of these using synchrotron radiation at the Advanced Photon Source. Results: The authors show that it is possible to achieve 250 eV energy resolution using an electron multiplying CCD operating in a quasiphoton-counting mode. Doing so allowed them to generate elemental images using both of the novel geometries for imaging of phantoms and, for the second geometry, an osmium-stained zebrafish. Conclusions: The authors have demonstrated the feasibility of these two novel approaches to XFCT imaging. While they use synchrotron radiation in this demonstration, the geometries could readily be translated to laboratory systems based on tube sources. PMID:23718594

  6. Industry-relevant magnetron sputtering and cathodic arc ultra-high vacuum deposition system for in situ x-ray diffraction studies of thin film growth using high energy synchrotron radiation.

    PubMed

    Schroeder, J L; Thomson, W; Howard, B; Schell, N; Näslund, L-Å; Rogström, L; Johansson-Jõesaar, M P; Ghafoor, N; Odén, M; Nothnagel, E; Shepard, A; Greer, J; Birch, J

    2015-09-01

    We present an industry-relevant, large-scale, ultra-high vacuum (UHV) magnetron sputtering and cathodic arc deposition system purposefully designed for time-resolved in situ thin film deposition/annealing studies using high-energy (>50 keV), high photon flux (>10(12) ph/s) synchrotron radiation. The high photon flux, combined with a fast-acquisition-time (<1 s) two-dimensional (2D) detector, permits time-resolved in situ structural analysis of thin film formation processes. The high-energy synchrotron-radiation based x-rays result in small scattering angles (<11°), allowing large areas of reciprocal space to be imaged with a 2D detector. The system has been designed for use on the 1-tonne, ultra-high load, high-resolution hexapod at the P07 High Energy Materials Science beamline at PETRA III at the Deutsches Elektronen-Synchrotron in Hamburg, Germany. The deposition system includes standard features of a typical UHV deposition system plus a range of special features suited for synchrotron radiation studies and industry-relevant processes. We openly encourage the materials research community to contact us for collaborative opportunities using this unique and versatile scientific instrument.

  7. Electronic structural changes of the electrochemically Li-ion deintercalated LiNi 0.8Co 0.15Al 0.05O 2 cathode material investigated by X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Yoon, Won-Sub; Chung, Kyung Yoon; McBreen, James; Fischer, Daniel A.; Yang, Xiao-Qing

    In situ hard X-ray absorption spectroscopy (XAS) at metal K-edges and soft XAS at O K-edge and metal L-edges have been carried out during the first charging process for the layered Li 1- xNi 0.8Co 0.15Al 0.05O 2 cathode material. The metal K-edge XAS results show that the major charge compensation at the metal site during Li-ion deintercalation is achieved by the oxidation of Ni ions, while the cobalt ions remain mostly unchanged in the Co 3+ state. Ni L II,III-edge and O K-edge XAS results in both the fluorescence yield (FY) and partial electron yield (PEY) modes show that substantial amount of Ni ions at the surface of LiNi 0.8Co 0.15Al 0.05O 2 powders exist as Ni 2+, whereas most of Ni ions in the bulk are in the form of Ni 3+. Therefore, if the PEY mode, which is a surface-sensitive technique, is used alone, the interpretation of the results is limited to the surface structures only. In order to get the full picture of both the surface and the bulk, the FY mode and PEY mode should be used simultaneously.

  8. A 5,000 hour xenon hollow cathode life test

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Garner, Charles E.

    1991-01-01

    A cathode life test voluntary terminated after 5024 hours of operation at 25 A is reported. The cathode including a 6.35-mm diameter by 57.12-mm long molybdenum tube with a nominal wall thickness of 0.38 mm is described along with a test facility and start-up procedure. It is shown that over the time of the experiment, the cathode-orifice diameter eroded from 1.80 mm to 2.08 mm, which corresponds to a ratio of the emission current to the orifice diameter at the end of the test of 12.0 A/mm. Tungsten deposits on the interior surface of the insert are detected in post-test analyses, and complete depletion of the original impregnate is suggested by X-ray diffraction analyses. A cathode-jet phenomenon in which energetic ions are produced during hollow-cathode operation at emission currents above 20 A is confirmed.

  9. A measurement-based X-ray source model characterization for CT dosimetry computations.

    PubMed

    Sommerville, Mitchell; Poirier, Yannick; Tambasco, Mauro

    2015-11-08

    The purpose of this study was to show that the nominal peak tube voltage potential (kVp) and measured half-value layer (HVL) can be used to generate energy spectra and fluence profiles for characterizing a computed tomography (CT) X-ray source, and to validate the source model and an in-house kV X-ray dose computation algorithm (kVDoseCalc) for computing machine- and patient-specific CT dose. Spatial variation of the X-ray source spectra of a Philips Brilliance and a GE Optima Big Bore CT scanner were found by measuring the HVL along the direction of the internal bow-tie filter axes. Third-party software, Spektr, and the nominal kVp settings were used to generate the energy spectra. Beam fluence was calculated by dividing the integral product of the spectra and the in-air NIST mass-energy attenuation coefficients by in-air dose measurements along the filter axis. The authors found the optimal number of photons to seed in kVDoseCalc to achieve dose convergence. The Philips Brilliance beams were modeled for 90, 120, and 140 kVp tube settings. The GE Optima beams were modeled for 80, 100, 120, and 140 kVp tube settings. Relative doses measured using a Capintec Farmer-type ionization chamber (0.65 cc) placed in a cylindrical polymethyl methacrylate (PMMA) phantom and irradiated by the Philips Brilliance, were compared to those computed with kVDoseCalc. Relative doses in an anthropomorphic thorax phantom (E2E SBRT Phantom) irradiated by the GE Optima were measured using a (0.015 cc) PTW Freiburg ionization chamber and compared to computations from kVDoseCalc. The number of photons required to reduce the average statistical uncertainty in dose to < 0.3% was 2 × 105. The average percent difference between calculation and measurement over all 12 PMMA phantom positions was found to be 1.44%, 1.47%, and 1.41% for 90, 120, and 140 kVp, respectively. The maximum percent difference between calculation and measurement for all energies, measurement positions, and phantoms was

  10. A measurement-based X-ray source model characterization for CT dosimetry computations.

    PubMed

    Sommerville, Mitchell; Poirier, Yannick; Tambasco, Mauro

    2015-01-01

    The purpose of this study was to show that the nominal peak tube voltage potential (kVp) and measured half-value layer (HVL) can be used to generate energy spectra and fluence profiles for characterizing a computed tomography (CT) X-ray source, and to validate the source model and an in-house kV X-ray dose computation algorithm (kVDoseCalc) for computing machine- and patient-specific CT dose. Spatial variation of the X-ray source spectra of a Philips Brilliance and a GE Optima Big Bore CT scanner were found by measuring the HVL along the direction of the internal bow-tie filter axes. Third-party software, Spektr, and the nominal kVp settings were used to generate the energy spectra. Beam fluence was calculated by dividing the integral product of the spectra and the in-air NIST mass-energy attenuation coefficients by in-air dose measurements along the filter axis. The authors found the optimal number of photons to seed in kVDoseCalc to achieve dose convergence. The Philips Brilliance beams were modeled for 90, 120, and 140 kVp tube settings. The GE Optima beams were modeled for 80, 100, 120, and 140 kVp tube settings. Relative doses measured using a Capintec Farmer-type ionization chamber (0.65 cc) placed in a cylindrical polymethyl methacrylate (PMMA) phantom and irradiated by the Philips Brilliance, were compared to those computed with kVDoseCalc. Relative doses in an anthropomorphic thorax phantom (E2E SBRT Phantom) irradiated by the GE Optima were measured using a (0.015 cc) PTW Freiburg ionization chamber and compared to computations from kVDoseCalc. The number of photons required to reduce the average statistical uncertainty in dose to < 0.3% was 2 × 105. The average percent difference between calculation and measurement over all 12 PMMA phantom positions was found to be 1.44%, 1.47%, and 1.41% for 90, 120, and 140 kVp, respectively. The maximum percent difference between calculation and measurement for all energies, measurement positions, and phantoms was

  11. Region of interest processing for iterative reconstruction in x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Kopp, Felix K.; Nasirudin, Radin A.; Mei, Kai; Fehringer, Andreas; Pfeiffer, Franz; Rummeny, Ernst J.; Noël, Peter B.

    2015-03-01

    The recent advancements in the graphics card technology raised the performance of parallel computing and contributed to the introduction of iterative reconstruction methods for x-ray computed tomography in clinical CT scanners. Iterative maximum likelihood (ML) based reconstruction methods are known to reduce image noise and to improve the diagnostic quality of low-dose CT. However, iterative reconstruction of a region of interest (ROI), especially ML based, is challenging. But for some clinical procedures, like cardiac CT, only a ROI is needed for diagnostics. A high-resolution reconstruction of the full field of view (FOV) consumes unnecessary computation effort that results in a slower reconstruction than clinically acceptable. In this work, we present an extension and evaluation of an existing ROI processing algorithm. Especially improvements for the equalization between regions inside and outside of a ROI are proposed. The evaluation was done on data collected from a clinical CT scanner. The performance of the different algorithms is qualitatively and quantitatively assessed. Our solution to the ROI problem provides an increase in signal-to-noise ratio and leads to visually less noise in the final reconstruction. The reconstruction speed of our technique was observed to be comparable with other previous proposed techniques. The development of ROI processing algorithms in combination with iterative reconstruction will provide higher diagnostic quality in the near future.

  12. Microanalysis of extended-test xenon hollow cathodes

    NASA Technical Reports Server (NTRS)

    Verhey, Timothy R.; Patterson, Michael J.

    1991-01-01

    Four hollow cathode electron sources were analyzed via boroscopy, scanning electron microscopy, energy dispersive x ray analysis, and x ray diffraction analysis. These techniques were used to develop a preliminary understanding of the chemistry of the devices that arise from contamination due to inadequate feed-system integrity and improper insert activation. Two hollow cathodes were operated in an ion thruster simulator at an emission current of 23.0 A for approximately 500 hrs. The two tests differed in propellant-feed systems, discharge power supplies, and activation procedures. Tungsten deposition and barium tungstate formation on the internal cathode surfaces occurred during the first test, which were believed to result from oxygen contamination of the propellant feed-system. Consequently, the test facility was upgraded to reduce contamination, and the test was repeated. The second hollow cathode was found to have experienced significantly less tungsten deposition. A second pair of cathodes examined were the discharge and the neutralizer hollow cathodes used in a life-test of a 30-cm ring-cusp ion thruster at a 5.5 kW power level. The cathodes' test history was documented and the post-test microanalyses are described. The most significant change resulting from the life-test was substantial tungsten deposition on the internal cathode surfaces, as well as removal of material from the insert surface. In addition, barium tungstate and molybdate were found on insert surfaces. As a result of the cathode examinations, procedures and approaches were proposed for improved discharge ignition and cathode longevity.

  13. Following ORR intermediates adsorbed on a Pt cathode catalyst during break-in of a PEM fuel cell by in operando X-ray absorption spectroscopy.

    PubMed

    Ramaker, D E; Korovina, A; Croze, V; Melke, J; Roth, C

    2014-07-21

    In operando X-ray absorption spectroscopy data using the Δμ X-ray Absorption Near Edge Spectroscopy (XANES) analysis procedure is used to follow the ORR intermediate adsorbate coverage on a working catalyst in a PEMFC during initial activation and break-in. The adsorbate coverage and log i (Tafel) curves reveal a strong correlation, i.e., an increase in adsorbate intermediate coverage poisons Pt sites thereby decreasing the current. A decrease in Pt-O bond strength commensurate with decrease in potential causes a sequence of different dominant adsorbate volcano curves to exist, namely first O, then OH, and then OOH exactly as predicted by the different ORR kinetics mechanisms. During break-in, the incipient O coverage coming from exposure to air during storage and MEA preparation is rather quickly removed, compared to the slower and more subtle nanoparticle morphological changes, such as the rounding of the Pt nanoparticle edges/corners and smoothing of the planar surfaces, driven by the nanoparticle's tendency to lower its surface energy. These morphological changes increase the Pt-Pt average coordination number, decrease the average Pt-O bond strength, and thereby decrease the coverage of ORR intermediates, allowing increase in the current.

  14. Modular Low-Heater-Power Cathode/Electron Gun Assembly for Microwave and Millimeter Wave Traveling Wave Tubes

    NASA Technical Reports Server (NTRS)

    Wintucky, Edwin G.

    2000-01-01

    A low-cost, low-mass, electrically efficient, modular cathode/electron gun assembly has been developed by FDE Inc. of Beaverton, Oregon, under a Small Business Innovation Research (SBIR) contract with the NASA Glenn Research Center at Lewis Field. This new assembly offers significant improvements in the design and manufacture of microwave and millimeter wave traveling-wave tubes (TWT's) used for radar and communications. It incorporates a novel, low-heater-power, reduced size and mass, high-performance barium dispenser type thermionic cathode and provides for easy integration of the cathode into a large variety of conventional TWT circuits. Among the applications are TWT's for Earth-orbiting communication satellites and for deep space communications, where future missions will require smaller spacecraft, higher data transfer rates (higher frequencies and radiofrequency output power), and greater electrical efficiency. A particularly important TWT application is in the microwave power module (a hybrid microwave/millimeter wave amplifier consisting of a low-noise solid-state driver, a small TWT, and an electronic power conditioner integrated into a single compact package), where electrical efficiency and thermal loading are critical factors and lower cost is needed for successful commercialization. The design and fabrication are based on practices used in producing cathode ray tubes (CRT's), which is one of the most competitive and efficient manufacturing operations in the world today. The approach used in the design and manufacture of thermionic cathodes and electron guns for CRT's has been optimized for fully automated production, standardization of parts, and minimization of costs. It is applicable to the production of similar components for microwave tubes, with the additional benefits of low mass and significantly lower cathode heater power (less than half that of dispenser cathodes presently used in TWT s). Modular cathode/electron gun assembly. The modular

  15. Cathode materials review

    SciTech Connect

    Daniel, Claus Mohanty, Debasish Li, Jianlin Wood, David L.

    2014-06-16

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO{sub 2} cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  16. Cathode materials review

    NASA Astrophysics Data System (ADS)

    Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood, David L.

    2014-06-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  17. Mixed polyanion glass cathodes: Iron phosphate vanadate glasses

    SciTech Connect

    Kercher, Andrew K; Ramey, Joanne Oxendine; Carroll, Kyler J; Kiggans Jr, James O; Veith, Gabriel M; Meisner, Roberta; Boatner, Lynn A; Dudney, Nancy J

    2014-01-01

    Mixed polyanion (MP) glasses have been investigated for use as cathodes in lithium ion batteries. MP glass cathodes are similar in composition to theoretically promising crystalline polyanionic (CP) cathodes (e.g., lithium cobalt phosphate, lithium manganese silicate), but with proper polyanion substitution, they can be designed to overcome the key shortcomings of CP cathodes, such as poor electrical conductivity and irreversible phase changes. Iron phosphate/vanadate glasses were chosen as a first demonstration of the MP glass concept. Polyanion substitution with vanadate was shown to improve the intercalation capacity of an iron phosphate glass from almost zero to full theoretical capacity. In addition, the MP glass cathodes also exhibited an unexpected second high-capacity electrochemical reaction. X-ray absorption near-edge structure (XANES) and x-ray diffraction (XRD) of cathodes from cells having different states of charge suggested that this second electrochemical reaction is a glass-state conversion reaction. With a first demonstration established, MP glass materials utilizing an intercalation and/or glass-state conversion reaction are promising candidates for future high-energy cathode research.

  18. Prediction of intramuscular fat levels in Texel lamb loins using X-ray computed tomography scanning.

    PubMed

    Clelland, N; Bunger, L; McLean, K A; Conington, J; Maltin, C; Knott, S; Lambe, N R

    2014-10-01

    For the consumer, tenderness, juiciness and flavour are often described as the most important factors for meat eating quality, all of which have a close association with intramuscular fat (IMF). X-ray computed tomography (CT) can measure fat, muscle and bone volumes and weights, in vivo in sheep and CT predictions of carcass composition have been used in UK sheep breeding programmes over the last few decades. This study aimed to determine the most accurate combination of CT variables to predict IMF percentage of M. longissimus lumborum in Texel lambs. As expected, predicted carcass fat alone accounted for a moderate amount of the variation (R(2)=0.51) in IMF. Prediction accuracies were significantly improved (Adj R(2)>0.65) using information on fat and muscle densities measured from three CT reference scans, showing that CT can provide an accurate prediction of IMF in the loin of purebred Texel sheep.

  19. Dual beam generation at a ray caustic by a multiplexing computer-generated hologram

    NASA Astrophysics Data System (ADS)

    Su, Peng; Hudman, Josh; Sasian, Jose M.; Dallas, William J.

    2005-06-01

    Computer generated holograms (CGHs) are used for testing aspherical surfaces. They are also used for certifying null lens systems that are in turn used to test large aspheric mirrors. We demonstrate that, in order to minimize size, a null-corrector-certifying CGH can be located at a ray caustic. This placement minimizes the required size of the CGH and so makes it possible to certify some null correctors that otherwise, due to current size limitations of high-precision CGHs, could not be certified. Fabrication limits of precision CGHs are in the size range of 200 250 mm and one part in 10^5 in feature placement. Our proof of principle involves a CGH that is about 20mm in diameter with a fabrication tolerance of one part in 10^4.

  20. Imaging of sand production in a horizontal sand pack by X-ray computed tomography

    SciTech Connect

    Tremblay, B.; Sedgwick, G.; Forshner, K.

    1996-06-01

    A laboratory experiment was performed to better understand how sand production can increase heavy oil recovery. A horizontal sand pack with an orifice at one end modeled the production of oil and sand into a perforation in a vertical well. The sand pack was scanned using X-ray computed tomography (CT). The CT images revealed that a high-porosity channel (wormhole) formed in the pack while sand was produced. The wormhole followed regions within the pack where the porosity was higher, and, consequently, the unconfined compressive strength of the sand was lower. This experiment suggests that wormholes will form within the weaker sands of a formation. The development of these high-permeability channels increases the drainage of the reservoir, which leads to higher oil recovery.

  1. An algebraic iterative reconstruction technique for differential X-ray phase-contrast computed tomography.

    PubMed

    Fu, Jian; Schleede, Simone; Tan, Renbo; Chen, Liyuan; Bech, Martin; Achterhold, Klaus; Gifford, Martin; Loewen, Rod; Ruth, Ronald; Pfeiffer, Franz

    2013-09-01

    Iterative reconstruction has a wide spectrum of proven advantages in the field of conventional X-ray absorption-based computed tomography (CT). In this paper, we report on an algebraic iterative reconstruction technique for grating-based differential phase-contrast CT (DPC-CT). Due to the differential nature of DPC-CT projections, a differential operator and a smoothing operator are added to the iterative reconstruction, compared to the one commonly used for absorption-based CT data. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured at a two-grating interferometer setup. Since the algorithm is easy to implement and allows for the extension to various regularization possibilities, we expect a significant impact of the method for improving future medical and industrial DPC-CT applications.

  2. Determination of Diffusion Profiles in Altered Wellbore Cement Using X-ray Computed Tomography Methods

    SciTech Connect

    Mason, Harris E.; Walsh, Stuart D. C.; DuFrane, Wyatt L.; Carroll, Susan A.

    2014-06-17

    The development of accurate, predictive models for use in determining wellbore integrity requires detailed information about the chemical and mechanical changes occurring in hardened Portland cements. X-ray computed tomography (XRCT) provides a method that can nondestructively probe these changes in three dimensions. Here, we describe a method for extracting subvoxel mineralogical and chemical information from synchrotron XRCT images by combining advanced image segmentation with geochemical models of cement alteration. The method relies on determining “effective linear activity coefficients” (ELAC) for the white light source to generate calibration curves that relate the image grayscales to material composition. The resulting data set supports the modeling of cement alteration by CO2-rich brine with discrete increases in calcium concentration at reaction boundaries. The results of these XRCT analyses can be used to further improve coupled geochemical and mechanical models of cement alteration in the wellbore environment.

  3. Synchrotron X-ray microprobe and computed microtomography for characterization of nanocatalysts

    NASA Astrophysics Data System (ADS)

    Jones, K. W.; Feng, H.; Lanzirotti, A.; Mahajan, D.

    2005-12-01

    Gas-to-liquids (GTL) is a viable pathway for synthesis of clean fuels from natural gas. One of the attractive synthesis options is the Fischer-Tropsch (F-T) method using an iron catalyst to yield a broad range of hydrocarbons. We collected catalyst samples during three separate F-T runs that utilized nanophase (mean particle diameter (MPD): 3 nm and 20-80 nm) and micrometer-sized (32.5 μm) Fe2O3 that served as catalyst precursors. The collected samples were characterized with micro-X-ray fluorescence and computed microtomography at the National Synchrotron Light Source (NSLS). Results found with two different measurement techniques indicated that there was heterogeneity on a spatial scale corresponding to volumes of roughly 103 μm3.

  4. X-ray computed tomography datasets for forensic analysis of vertebrate fossils

    PubMed Central

    Rowe, Timothy B.; Luo, Zhe-Xi; Ketcham, Richard A.; Maisano, Jessica A.; Colbert, Matthew W.

    2016-01-01

    We describe X-ray computed tomography (CT) datasets from three specimens recovered from Early Cretaceous lakebeds of China that illustrate the forensic interpretation of CT imagery for paleontology. Fossil vertebrates from thinly bedded sediments often shatter upon discovery and are commonly repaired as amalgamated mosaics grouted to a solid backing slab of rock or plaster. Such methods are prone to inadvertent error and willful forgery, and once required potentially destructive methods to identify mistakes in reconstruction. CT is an efficient, nondestructive alternative that can disclose many clues about how a specimen was handled and repaired. These annotated datasets illustrate the power of CT in documenting specimen integrity and are intended as a reference in applying CT more broadly to evaluating the authenticity of comparable fossils. PMID:27272251

  5. X-ray computed tomography datasets for forensic analysis of vertebrate fossils.

    PubMed

    Rowe, Timothy B; Luo, Zhe-Xi; Ketcham, Richard A; Maisano, Jessica A; Colbert, Matthew W

    2016-01-01

    We describe X-ray computed tomography (CT) datasets from three specimens recovered from Early Cretaceous lakebeds of China that illustrate the forensic interpretation of CT imagery for paleontology. Fossil vertebrates from thinly bedded sediments often shatter upon discovery and are commonly repaired as amalgamated mosaics grouted to a solid backing slab of rock or plaster. Such methods are prone to inadvertent error and willful forgery, and once required potentially destructive methods to identify mistakes in reconstruction. CT is an efficient, nondestructive alternative that can disclose many clues about how a specimen was handled and repaired. These annotated datasets illustrate the power of CT in documenting specimen integrity and are intended as a reference in applying CT more broadly to evaluating the authenticity of comparable fossils. PMID:27272251

  6. Data Acquisition, Control, Communication and Computation System of Solar X-ray Spectrometer (SOXS) Mission

    NASA Astrophysics Data System (ADS)

    Shah, Amish B.; Vadher, N. M.; Jain, Rajma; Dave, Hemant; Shah, Vishal; Manian, K. S. B.; Kayasth, Satish; Patel, Vinod; Ubale, Girish; Shah, Kirit; Solanki, Chirag; Deshpande, M. R.; Sharma, Ramkrishna; Umapathy, C. N.; Viswanath, N.; Kulkarni, Ravi; Kumar, P. S.

    2006-09-01

    The Solar X-ray Spectrometer (SOXS) mission onboardGSAT- 2 Indian Spacecraft was launched on 08 May 2003 using GSLV-D2 rocket by Indian Space Research Organization (ISRO). SOXS aims to study solar flares, which are the most violent and energetic phenomena in the solar system, in the energy range of 4-56 keV with high spectral and temporal resolution. SOXS employs state-of-the-art semiconductor devices, viz., Si-Pin and CZT detectors to achieve sub-keV energy resolution requirements. In this paper, we present an overview of data acquisition, control,communication and computation of low energy payload of the SOXS mission.

  7. A new method of performance verification for x-ray computed tomography measurements

    NASA Astrophysics Data System (ADS)

    Léonard, F.; Brown, S. B.; Withers, P. J.; Mummery, P. M.; McCarthy, M. B.

    2014-06-01

    Through its ability to measure otherwise inaccessible internal structures, x-ray computed tomography (CT) has become a useful tool in the field of dimensional metrology. However, the lack of international standards for performance verification and the determination of metrological characteristics has so far prevented it from becoming a standardized measurement technology. This paper considers how a test object comprising a dismantleable tetrahedral assembly of four calibrated alumina spheres can be employed to assess the metrological performance of an industrial-type CT system. The measurement accuracy was characterized in terms of sphere size, separation and form errors. In all cases, sub-voxel accuracy was achieved, with errors as small as 1/10 of a voxel being obtained. Good measurement repeatability was demonstrated even upon dismantling and reconstructing the reference object. The tetrahedral test object offers a simple robust solution for the verification of metrological performance with great versatility and adaptability.

  8. X-ray computed tomography datasets for forensic analysis of vertebrate fossils.

    PubMed

    Rowe, Timothy B; Luo, Zhe-Xi; Ketcham, Richard A; Maisano, Jessica A; Colbert, Matthew W

    2016-06-07

    We describe X-ray computed tomography (CT) datasets from three specimens recovered from Early Cretaceous lakebeds of China that illustrate the forensic interpretation of CT imagery for paleontology. Fossil vertebrates from thinly bedded sediments often shatter upon discovery and are commonly repaired as amalgamated mosaics grouted to a solid backing slab of rock or plaster. Such methods are prone to inadvertent error and willful forgery, and once required potentially destructive methods to identify mistakes in reconstruction. CT is an efficient, nondestructive alternative that can disclose many clues about how a specimen was handled and repaired. These annotated datasets illustrate the power of CT in documenting specimen integrity and are intended as a reference in applying CT more broadly to evaluating the authenticity of comparable fossils.

  9. REFLECT: A computer program for the x-ray reflectivity of bent perfect crystals

    SciTech Connect

    Etelaeniemi, V.; Suortti, P.; Thomlinson, W. . Dept. of Physics; Brookhaven National Lab., Upton, NY )

    1989-09-01

    The design of monochromators for x-ray applications, using either standard laboratory sources on synchrotron radiation sources, requires a knowledge of the reflectivity of the crystals. The reflectivity depends on the crystals used, the geometry of the reflection, the energy range of the radiation, and, in the present case, the cylindrical bending radius of the optical device. This report is intended to allow the reader to become familiar with, and therefore use, a computer program called REFLECT which we have used in the design of a dual beam Laue monochromator for synchrotron angiography. The results of REFLECT have been compared to measured reflectivities for both bent Bragg and Laue geometries. The results are excellent and should give full confidence in the use of the program. 6 refs.

  10. The X-ray system of crystallographic programs for any computer having a PIDGIN FORTRAN compiler

    NASA Technical Reports Server (NTRS)

    Stewart, J. M.; Kruger, G. J.; Ammon, H. L.; Dickinson, C.; Hall, S. R.

    1972-01-01

    A manual is presented for the use of a library of crystallographic programs. This library, called the X-ray system, is designed to carry out the calculations required to solve the structure of crystals by diffraction techniques. It has been implemented at the University of Maryland on the Univac 1108. It has, however, been developed and run on a variety of machines under various operating systems. It is considered to be an essentially machine independent library of applications programs. The report includes definition of crystallographic computing terms, program descriptions, with some text to show their application to specific crystal problems, detailed card input descriptions, mass storage file structure and some example run streams.

  11. Determination of diffusion profiles in altered wellbore cement using X-ray computed tomography methods.

    PubMed

    Mason, Harris E; Walsh, Stuart D C; DuFrane, Wyatt L; Carroll, Susan A

    2014-06-17

    The development of accurate, predictive models for use in determining wellbore integrity requires detailed information about the chemical and mechanical changes occurring in hardened Portland cements. X-ray computed tomography (XRCT) provides a method that can nondestructively probe these changes in three dimensions. Here, we describe a method for extracting subvoxel mineralogical and chemical information from synchrotron XRCT images by combining advanced image segmentation with geochemical models of cement alteration. The method relies on determining "effective linear activity coefficients" (ELAC) for the white light source to generate calibration curves that relate the image grayscales to material composition. The resulting data set supports the modeling of cement alteration by CO2-rich brine with discrete increases in calcium concentration at reaction boundaries. The results of these XRCT analyses can be used to further improve coupled geochemical and mechanical models of cement alteration in the wellbore environment. PMID:24869420

  12. Thermionic cathode life test studies

    NASA Technical Reports Server (NTRS)

    Forman, R.; Elmer, P.

    1980-01-01

    An update on the life testing of commerical, high current density impregnated tungsten cathodes is presented. The B-type cathodes, operated at a current density of 2 A/cm2 and a cathode temperature of 1100 C have now been run satisfactorily for more than four years. The M-cathode, at the same current density but at an operating temperature of only 1010 C, have been tested for more than three years. The M-cathodes show no degradation in current over their present operating life whereas the current from the B-cathodes degrade about 6 percent after four years of operation.

  13. Cavity-hollow cathode-sputtering source for titanium films

    NASA Astrophysics Data System (ADS)

    Schrittwieser, R.; Ionita, C.; Murawski, A.; Maszl, C.; Asandulesa, M.; Nastuta, A.; Rusu, G.; Douat, C.; Olenici, S. B.; Vojvodic, I.; Dobromir, M.; Luca, D.; Jaksch, S.; Scheier, P.

    2010-08-01

    A cavity-hollow cathode was investigated as low-cost sputtering source for titanium. An argon discharge is produced inside a hollow cathode consisting of two specifically formed disks of titanium. An additional cavity further enhances the pendulum effect of the electrons. Measurements with small Langmuir probes yielded evidence for the formation of a space charge double layer above the cathode. The sputtered atoms form negatively charged clusters. After further acceleration by the double layer the clusters impinge on the substrates. Titanium thin films were produced on highly oriented pyrolytic graphite. The films were investigated by a scanning tunnel microscope and X-ray photoelectron spectroscopy.

  14. Development of an X-ray Computed Tomography System for Non-Invasive Imaging of Industrial Materials

    SciTech Connect

    Abdullah, J.; Sipaun, S. M.; Mustapha, I.; Zain, R. M.; Rahman, M. F. A.; Mustapha, M.; Shaari, M. R.; Hassan, H.; Said, M. K. M.; Mohamad, G. H. P.; Ibrahim, M. M.

    2008-05-20

    X-ray computed tomography is a powerful non-invasive imaging technique for viewing an object's inner structures in two-dimensional cross-section images without the need to physically section it. The invention of CT techniques revolutionised the field of medical diagnostic imaging because it provided more detailed and useful information than any previous non-invasive imaging techniques. The method is increasingly being used in industry, aerospace, geosciences and archaeology. This paper describes the development of an X-ray computed tomography system for imaging of industrial materials. The theoretical aspects of CT scanner, the system configurations and the adopted algorithm for image reconstruction are discussed. The penetrating rays from a 160 kV industrial X-ray machine were used to investigate structures that manifest in a manufactured component or product. Some results were presented in this paper.

  15. Searching for Narrow Emission Lines in X-ray Spectra: Computation and Methods

    NASA Astrophysics Data System (ADS)

    Park, Taeyoung; van Dyk, David A.; Siemiginowska, Aneta

    2008-12-01

    The detection and quantification of narrow emission lines in X-ray spectra is a challenging statistical task. The Poisson nature of the photon counts leads to local random fluctuations in the observed spectrum that often result in excess emission in a narrow band of energy resembling a weak narrow line. From a formal statistical perspective, this leads to a (sometimes highly) multimodal likelihood. Many standard statistical procedures are based on (asymptotic) Gaussian approximations to the likelihood and simply cannot be used in such settings. Bayesian methods offer a more direct paradigm for accounting for such complicated likelihood functions, but even here multimodal likelihoods pose significant computational challenges. The new Markov chain Monte Carlo (MCMC) methods developed in 2008 by van Dyk and Park, however, are able to fully explore the complex posterior distribution of the location of a narrow line, and thus provide valid statistical inference. Even with these computational tools, standard statistical quantities such as means and standard deviations cannot adequately summarize inference and standard testing procedures cannot be used to test for emission lines. In this paper, we use new efficient MCMC algorithms to fit the location of narrow emission lines, we develop new statistical strategies for summarizing highly multimodal distributions and quantifying valid statistical inference, and we extend the method of posterior predictive p-values proposed by Protassov and coworkers to test for the presence of narrow emission lines in X-ray spectra. We illustrate and validate our methods using simulation studies and apply them to the Chandra observations of the high-redshift quasar PG 1634+706.

  16. Development of a prototype gantry system for preclinical x-ray phase-contrast computed tomography

    SciTech Connect

    Tapfer, Arne; Bech, Martin; Pauwels, Bart; Liu Xuan; Bruyndonckx, Peter; Sasov, Alexander; Kenntner, Johannes; Mohr, Juergen; Walter, Marco; Schulz, Joachim; Pfeiffer, Franz

    2011-11-15

    Purpose: To explore the potential of grating-based x-ray phase-contrast imaging for clinical applications, a first compact gantry system was developed. It is designed such that it can be implemented into an in-vivo small-animal phase-contrast computed tomography (PC-CT) scanner. The purpose of the present study is to assess the accuracy and quantitativeness of the described gantry in both absorption and phase-contrast. Methods: A phantom, containing six chemically well-defined liquids, was constructed. A tomography scan with cone-beam reconstruction of this phantom was performed yielding the spatial distribution of the linear attenuation coefficient {mu} and decrement {delta} of the complex refractive index. Theoretical values of {mu} and {delta} were calculated for each liquid from tabulated data and compared with the experimentally measured values. Additionally, a color-fused image representation is proposed to display the complementary absorption and phase-contrast information in a single image. Results: Experimental and calculated data of the phantom agree well confirming the quantitativeness and accuracy of the reconstructed spatial distributions of {mu} and {delta}. The proposed color-fused image representation, which combines the complementary absorption and phase information, considerably helps in distinguishing the individual substances. Conclusions: The concept of grating-based phase-contrast computed tomography (CT) can be implemented into a compact, cone-beam geometry gantry setup. The authors believe that this work represents an important milestone in translating phase-contrast x-ray imaging from previous proof-of-principle experiments to first preclinical biomedical imaging applications on small-animal models.

  17. Clogging evaluation of porous asphalt concrete cores in conjunction with medical x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Su, Yu-Min; Hsu, Chen-Yu; Lin, Jyh-Dong

    2014-03-01

    This study was to assess the porosity of Porous Asphalt Concrete (PAC) in conjunction with a medical X-ray computed tomography (CT) facility. The PAC was designed as the surface course to achieve the target porosity 18%. There were graded aggregates, soils blended with 50% of coarse sand, and crushed gravel wrapped with geotextile compacted and served as the base, subbase, and infiltration layers underneath the PAC. The test site constructed in 2004 is located in Northern of Taiwan in which the daily traffic has been light and limited. The porosity of the test track was investigated. The permeability coefficient of PAC was found severely degraded from 2.2×10-1 to 1.2×10-3 -cm/sec, after nine-year service, while the permeability below the surface course remained intact. Several field PAC cores were drilled and brought to evaluate the distribution of air voids by a medical X-ray CT nondestructively. The helical mode was set to administrate the X-ray CT scan and two cross-sectional virtual slices were exported in seconds for analyzing air voids distribution. It shows that the clogging of voids occurred merely 20mm below the surface and the porosity can reduce as much about 3%. It was also found that the roller compaction can decrease the porosity by 4%. The permeability reduction in this test site can attribute to the voids of PAC that were compacted by roller during the construction and filled by the dusts on the surface during the service.

  18. X-ray scatter correction method for dedicated breast computed tomography

    SciTech Connect

    Sechopoulos, Ioannis

    2012-05-15

    Purpose: To improve image quality and accuracy in dedicated breast computed tomography (BCT) by removing the x-ray scatter signal included in the BCT projections. Methods: The previously characterized magnitude and distribution of x-ray scatter in BCT results in both cupping artifacts and reduction of contrast and accuracy in the reconstructions. In this study, an image processing method is proposed that estimates and subtracts the low-frequency x-ray scatter signal included in each BCT projection postacquisition and prereconstruction. The estimation of this signal is performed using simple additional hardware, one additional BCT projection acquisition with negligible radiation dose, and simple image processing software algorithms. The high frequency quantum noise due to the scatter signal is reduced using a noise filter postreconstruction. The dosimetric consequences and validity of the assumptions of this algorithm were determined using Monte Carlo simulations. The feasibility of this method was determined by imaging a breast phantom on a BCT clinical prototype and comparing the corrected reconstructions to the unprocessed reconstructions and to reconstructions obtained from fan-beam acquisitions as a reference standard. One-dimensional profiles of the reconstructions and objective image quality metrics were used to determine the impact of the algorithm. Results: The proposed additional acquisition results in negligible additional radiation dose to the imaged breast ({approx}0.4% of the standard BCT acquisition). The processed phantom reconstruction showed substantially reduced cupping artifacts, increased contrast between adipose and glandular tissue equivalents, higher voxel value accuracy, and no discernible blurring of high frequency features. Conclusions: The proposed scatter correction method for dedicated breast CT is feasible and can result in highly improved image quality. Further optimization and testing, especially with patient images, is necessary to

  19. Positioning Standardized Acupuncture Points on the Whole Body Based on X-Ray Computed Tomography Images

    PubMed Central

    Kim, Jungdae

    2014-01-01

    Abstract Objective: The goal of this research was to position all the standardized 361 acupuncture points on the entire human body based on a 3-dimensional (3D) virtual body. Materials and Methods: Digital data from a healthy Korean male with a normal body shape were obtained in the form of cross-sectional images generated by X-ray computed tomography (CT), and the 3D models for the bones and the skin's surface were created through the image-processing steps. Results: The reference points or the landmarks were positioned based on the standard descriptions of the acupoints, and the formulae for the proportionalities between the acupoints and the reference points were presented. About 37% of the 361 standardized acupoints were automatically linked with the reference points, the reference points accounted for 11% of the 361 acupoints, and the remaining acupoints (52%) were positioned point-by-point by using the OpenGL 3D graphics libraries. Based on the projective 2D descriptions of the standard acupuncture points, the volumetric 3D acupoint model was developed; it was extracted from the X-ray CT images. Conclusions: This modality for positioning acupoints may modernize acupuncture research and enable acupuncture treatments to be more personalized. PMID:24761187

  20. High energy x-ray radiography and computed tomography of bridge pins

    SciTech Connect

    Green, R E; Logan, C M; Martz, H E; Updike, E; Waters, A M

    1999-05-01

    Bridge pins were used in the hanger assemblies for some multi-span steel bridges built prior to the 1980's, and are sometimes considered fracture critical elements of a bridge. During a test on a bridge conducted by the Federal Highway Administration (FHWA), ultrasonic field inspection results indicated that at least two pins contained cracks. Several pins were removed and selected for further examination. This provided an excellent opportunity to learn more about these pins and the application of x-ray systems at Lawrence Livermore National Laboratory (LLNL), as well as to learn more about the application of different detectors recently obtained by LLNL. Digital radiographs and computed tomography (CT) were used to characterize the bridge pins, using a LINAC x-ray source with a 9-MV bremsstrahlung spectrum. We will describe the performance of two different digital radiographic detectors. One is a detector system frequently used at LLNL consisting of a scintillator glass optically coupled to a CCD camera. The other detector is a new amorphous silicon detector recently acquired by LLNL.

  1. Assessing potato tuber diel growth by means of X-ray computed tomography.

    PubMed

    Pérez-Torres, Eduardo; Kirchgessner, Norbert; Pfeifer, Johannes; Walter, Achim

    2015-11-01

    The formation and development of belowground organs is difficult to study. X-ray computed tomography (CT) provides the possibility to analyse and interpret subtle volumetric changes of belowground organs such as tubers, storage roots and nodules. Here, we report on the establishment of a method based on a voxel dimension of 240 μm and precision (standard deviation) of 30 μL that allows interpreting growth differences among potato tubers happening within 3 h. Plants were not stressed by the application of X-ray radiation, which was shown both by morphological comparison with control plants and by analysis of lipid peroxidation as a measure of oxidative stress. Diel (24 h) tuber growth fluctuations of three potato genotypes were monitored in soil-filled pots of 10 L. In contrast to the results from previous reports, most tubers grew at similar rates during day and night. Tuber growth was not related to the developmental stage of plants and tubers. Pronounced differences were observed between average growth rates in different tubers within a plant. These results are discussed in the context of restrictions of past methods to study tuber growth and in the context of their potential for the characterization of the formation and development of other belowground plant organs.

  2. Investigation of soil structure development and properties of macropore networks with X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Pagenkemper, Sebastian; Uteau Puschmann, Daniel; Peth, Stephan; Horn, Rainer

    2014-05-01

    X-ray computed tomography provides a non-destructive method to visualize and quantify three-dimensional pore networks. Geometrical and morphological parameters of the complex pore system such as connectivity, tortuosity, porosity and pore surface area would be very useful for modeling and simulating of transport and exchange processes. Thus, quantitative data on relevant soil structural features and their modification by soil management could be provided. The scope of this study was to analyze and quantify the development of soil structure in the subsoil depending on three different precrop species (alfalfa, chicory and fescue), at three depths (45, 60 and 75 cm) and three cultivation periods (1, 2 and 3 yrs) on an experimental field trial (Germany) with a Haplic Luvisol as major soil type. Morphological (air-filled porosity, pore surface area) and geometrical (pore diameter, connectivity, continuity, tortuosity) parameters were gathered with X-ray CT and evaluated with image analysis. Furthermore, the results were linked with air-capacity data from laboratory measurements to validate the data and with tortuosity/connectivity data from diffusion-based measurements. Air-filled porosity was highest for alfalfa (3 yrs, 75 cm). Tortuosity values ranged between 1.3 and 4.38, while alfalfa (3 yrs) showed the highest value, which may indicate structural development due to crack formation by enhanced root water uptake. An increase in accessible surfaces may improve water and nutrient supply for plants, whereas the high tortuosity values may also assume that oxygen supply is limited.

  3. In situ ray tracing and computational steering for interactive blood flow simulation

    NASA Astrophysics Data System (ADS)

    Mazzeo, Marco D.; Manos, Steven; Coveney, Peter V.

    2010-02-01

    Recent algorithm and hardware developments have significantly improved our capability to interactively visualise time-varying flow fields. However, when visualising very large dynamically varying datasets interactively there are still limitations in the scalability and efficiency of these methods. Here we present a rendering pipeline which employs an efficient in situ ray tracing technique to visualise flow fields as they are simulated. The ray casting approach is particularly well suited for the visualisation of large and sparse time-varying datasets, where it is capable of rendering fluid flow fields at high image resolutions and at interactive frame rates on a single multi-core processor using OpenMP. The parallel implementation of our in situ visualisation method relies on MPI, requires no specialised hardware support, and employs the same underlying spatial decomposition as the fluid simulator. The visualisation pipeline allows the user to operate on a commodity computer and explore the simulation output interactively. Our simulation environment incorporates numerous features that can be utilised in a wide variety of research contexts.

  4. The exploration study of fire damage to concrete specimen using x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Su, Yu-Min; Lee, Min-Gin; Chen, Guan-Ying

    2015-04-01

    Portland Cement Concrete (PCC) loses the evaporable water at about 100 °C, decomposes C-S-H at about 200 °C, and dehydrates CH at about 500 °C, and deconstruct C-S-H at about 900°C. The concrete degradation or cracks are caused by several possible parameters, such as vapor pressure in pores, thermal gradient, and varied expansion rates of cement pastes and aggregates. The objective of the exploration study was to assess the porosity before and after conditioning of high temperature in the laboratory with the medical X-ray computed tomography. The experimental program was determined to identify the mineral properties of the aggregates used and determine the consensus properties of compressive, splitting tensile, and flexural strengths. Concrete cylinders were subject with one temperature conditioning, namely 400°C, but two different heat conditioning time namely four and eight hours. The X-ray CT, before and after high temperature conditioning, was administrated on the concrete cylinders to inspect the depth of the damage zone, which shall consist of more porosity than undamaged one. The damage zone will be examined and identified through the changes in porosity of concrete paste and aggregates within a concrete cylinder. The significance of the exploration study was to provide an in-depth insight to define the damaged zone for a better understanding of the following repairing and reinforced work.

  5. Coded aperture x-ray diffraction imaging with transmission computed tomography side-information

    NASA Astrophysics Data System (ADS)

    Odinaka, Ikenna; Greenberg, Joel A.; Kaganovsky, Yan; Holmgren, Andrew; Hassan, Mehadi; Politte, David G.; O'Sullivan, Joseph A.; Carin, Lawrence; Brady, David J.

    2016-03-01

    Coded aperture X-ray diffraction (coherent scatter spectral) imaging provides fast and dose-efficient measurements of the molecular structure of an object. The information provided is spatially-dependent and material-specific, and can be utilized in medical applications requiring material discrimination, such as tumor imaging. However, current coded aperture coherent scatter spectral imaging system assume a uniformly or weakly attenuating object, and are plagued by image degradation due to non-uniform self-attenuation. We propose accounting for such non-uniformities in the self-attenuation by utilizing an X-ray computed tomography (CT) image (reconstructed attenuation map). In particular, we present an iterative algorithm for coherent scatter spectral image reconstruction, which incorporates the attenuation map, at different stages, resulting in more accurate coherent scatter spectral images in comparison to their uncorrected counterpart. The algorithm is based on a spectrally grouped edge-preserving regularizer, where the neighborhood edge weights are determined by spatial distances and attenuation values.

  6. X-ray cone-beam computed tomography: principles, applications, challenges and solutions

    NASA Astrophysics Data System (ADS)

    Noo, Frederic

    2010-03-01

    In the nineties, x-ray computed tomography, commonly referred to as CT, seemed to be on the track to become old technology, bound to be replaced by more sophisticated techniques such as magnetic resonance imaging, due in particular to the harmful effects of x-ray radiation exposure. Yet, the new century brought with it new technology that allowed a complete change in trends and re-affirmed CT as an essential tool in radiology. For instance, the popularity of CT in 2007 was such that approximately 68.7 million CT examinations were performed in the United States, which was nearly 2.5 times the number of magnetic resonance (MRI) examinations. More than that, CT has expanded beyond its conventional diagnostic role; CT is now used routinely in interventional radiology and also in radiation therapy treatment. The technology advances that allowed the revival of CT are those that made fast, accurate cone-beam data acquisition possible. Nowadays, cone-beam data acquisition allows scanning large volumes with isotropic sub-millimeter spatial resolution in a very fast time, which can be as short as 500ms for cardiac imaging. The principles of cone-beam imaging will be first reviewed. Then a discussion of its applications will be given. Old and new challenges will be presented along the way with current solutions.

  7. Impurity precipitation in atomized particles evidenced by nano x-ray diffraction computed tomography

    SciTech Connect

    Bonnin, Anne; Wright, Jonathan P.; Tucoulou, Rémi; Palancher, Hervé

    2014-08-25

    Performances and physical properties of high technology materials are influenced or even determined by their initial microstructure and by the behavior of impurity phases. Characterizing these impurities and their relations with the surrounding matrix is therefore of primary importance but it unfortunately often requires a destructive approach, with the risk of misinterpreting the observations. The improvement we have done in high resolution X-ray diffraction computed tomography combined with the use of an X-ray nanoprobe allows non-destructive crystallographic description of materials with microscopic heterogeneous microstructure (with a grain size between 10 nm and 10 μm). In this study, the grain localization in a 2D slice of a 20 μm solidified atomized γU-Mo particle is shown and a minority U(C,O) phase (1 wt. %) with sub-micrometer sized grains was characterized inside. Evidence is presented showing that the onset of U(C,O) grain crystallization can be described by a precipitation mechanism since one single U-Mo grain has direct orientation relationship with more than one surrounding U(C,O) grains.

  8. Deformulation of a solid pharmaceutical form using computed tomography and X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Oliveira Junior, J. M.; Balcão, V. M.; Vila, M. M. D. C.; Aranha, N.; Yoshida, V. M. H.; Chaud, M. V.; Mangine Filho, S.

    2015-07-01

    Deformulation of medicines is of undeniable importance, since it can be utilized both to unravel the chemical composition of the excipients integrating a pharmaceutical formulation of a specific medicine and as an important tool to conduct morphometric studies of the formulation under study. Such strategy may be utilized in analytical studies aiming at quantifying the components of reference drugs, or in the identification of putative counterfeit pharmaceuticals. Deformulation makes use of physicochemical analysis tools to characterize, from the chemical point of view, the components integrating medicine pharmaceutical formulations and from the physical point of view, the morphological part of the pharmaceutical formulation. The techniques of computer tomography (SkyScan 1174 - Bruker microCT) and X-ray fluorescence analyses (using an X-ray source with W-anode from Hammatsu Photonics and Silicon Drift detector from Amptek) were successfully used in performing a process of deformulation of a solid pharmaceutical formulation of tablets, utilized herein as a model medicine for controlled drug release. The analytical methods used in this work, proved their effectiveness for the main goal of this study, which aimed to characterize a pharmaceutical formulation via its deconstruction.

  9. On-Site Geologic Core Analysis Using a Portable X-ray ComputedTomographic System

    SciTech Connect

    Freifeld, Barry M.; Kneafsey, Timothy J.; Rack, Frank

    2004-03-01

    X-ray computed tomography (CT) is an established techniquefor nondestructively characterizing geologic cores. CT providesinformation on sediment structure, diagenetic alteration, fractures, flowchannels and barriers, porosity, and fluid-phase saturation. A portableCT imaging system has been developed specifically for imaging whole-roundcores at the drilling site. The new system relies upon carefully designedradiological shielding to minimize the size and weight of the resultinginstrument. Specialized x-ray beam collimators and filters maximizesystem sensitivity and performance. The system has been successfullydeployed on the research vessel Joides Resolution for Ocean DrillingProgram's Leg 204 and 210, within the Ocean Drilling Program'srefrigerated Gulf Coast Core Repository, as well as on the Hot Ice #1drilling platform located near the Kuparuk Field, Alaska. A methodologyfor performingsimple densiometry measurements, as well as scanning forgross structural features, will be presented using radiographs from ODPLeg 204. Reconstructed CT images from Hot Ice #1 will demonstrate the useof CT for discerning core textural features. To demonstrate the use of CTto quantitatively interpret dynamic processes, we calculate 95 percentconfidence intervals for density changes occurring during a laboratorymethane hydrate dissociation experiment. The field deployment of a CTrepresents a paradigm shift in core characterization, opening up thepossibility for rapid systematic characterization of three-dimensionalstructural features and leading to improved subsampling andcore-processing procedures.

  10. Cone beam x-ray luminescence computed tomography reconstruction with a priori anatomical information

    NASA Astrophysics Data System (ADS)

    Lo, Pei-An; Lin, Meng-Lung; Jin, Shih-Chun; Chen, Jyh-Cheng; Lin, Syue-Liang; Chang, C. Allen; Chiang, Huihua Kenny

    2014-09-01

    X-ray luminescence computed tomography (XLCT) is a novel molecular imaging modality that reconstructs the optical distribution of x-ray-excited phosphor particles with prior informational of anatomical CT image. The prior information improves the accuracy of image reconstruction. The system can also present anatomical CT image. The optical system based on a high sensitive charge coupled device (CCD) is perpendicular with a CT system. In the XLCT system, the xray was adopted to excite the phosphor of the sample and CCD camera was utilized to acquire luminescence emitted from the sample in 360 degrees projection free-space. In this study, the fluorescence diffuse optical tomography (FDOT)-like algorithm was used for image reconstruction, the structural prior information was incorporated in the reconstruction by adding a penalty term to the minimization function. The phosphor used in this study is Gd2O2S:Tb. For the simulation and experiments, the data was collected from 16 projections. The cylinder phantom was 40 mm in diameter and contains 8 mm diameter inclusion; the phosphor in the in vivo study was 5 mm in diameter at a depth of 3 mm. Both the errors were no more than 5%. Based on the results from these simulation and experimental studies, the novel XLCT method has demonstrated the feasibility for in vivo animal model studies.

  11. Assessing potato tuber diel growth by means of X-ray computed tomography.

    PubMed

    Pérez-Torres, Eduardo; Kirchgessner, Norbert; Pfeifer, Johannes; Walter, Achim

    2015-11-01

    The formation and development of belowground organs is difficult to study. X-ray computed tomography (CT) provides the possibility to analyse and interpret subtle volumetric changes of belowground organs such as tubers, storage roots and nodules. Here, we report on the establishment of a method based on a voxel dimension of 240 μm and precision (standard deviation) of 30 μL that allows interpreting growth differences among potato tubers happening within 3 h. Plants were not stressed by the application of X-ray radiation, which was shown both by morphological comparison with control plants and by analysis of lipid peroxidation as a measure of oxidative stress. Diel (24 h) tuber growth fluctuations of three potato genotypes were monitored in soil-filled pots of 10 L. In contrast to the results from previous reports, most tubers grew at similar rates during day and night. Tuber growth was not related to the developmental stage of plants and tubers. Pronounced differences were observed between average growth rates in different tubers within a plant. These results are discussed in the context of restrictions of past methods to study tuber growth and in the context of their potential for the characterization of the formation and development of other belowground plant organs. PMID:25850677

  12. Computer assisted gamma and X-ray tomography: Applications to multiphase flow systems

    SciTech Connect

    Kumar, S.B.; Dudukovic, M.

    1998-01-01

    In process vessels, involving two or three phases it is often important not only to know the volume fraction (holdup) of each phase but also the spatial distribution of such holdups. This information is needed in control, trouble shooting and assessment of flow patterns and can be observed noninvasively by the application of Computed Tomography (CT). This report presents a complete overview of X-ray and gamma ray transmission tomography principles, equipment design to specific tasks and application in process industry. The fundamental principles of tomography, the algorithms for image reconstruction, the measurement method and the possible sources of error are discussed in detail. A case study highlights the methodology involved in designing a scanning system for the study of a given process unit, e.g., reactor, separations column etc. Results obtained in the authors` laboratory for the gas holdup distribution in bubble columns are also presented. Recommendations are made for the Advanced Fuels Development Unit (AFDU) in LaPorte, TX.

  13. Chromatin structure revealed by X-ray scattering analysis and computational modeling.

    PubMed

    Maeshima, Kazuhiro; Imai, Ryosuke; Hikima, Takaaki; Joti, Yasumasa

    2014-12-01

    It remains unclear how the 2m of human genomic DNA is organized in each cell. The textbook model has long assumed that the 11-nm-diameter nucleosome fiber (beads-on-a-string), in which DNA is wrapped around core histones, is folded into a 30-nm chromatin fiber. One of the classical models assumes that the 30-nm chromatin fiber is further folded helically to form a larger fiber. Small-angle X-ray scattering (SAXS) is a powerful method for investigating the bulk structure of interphase chromatin and mitotic chromosomes. SAXS can detect periodic structures in biological materials in solution. In our SAXS results, no structural feature larger than 11 nm was detected. Combining this with a computational analysis of "in silico condensed chromatin" made it possible to understand more about the X-ray scattering profiles and suggested that the chromatin in interphase nuclei and mitotic chromosomes essentially consists of irregularly folded nucleosome fibers lacking the 30-nm chromatin structure. In this article, we describe the experimental details of our SAXS and modeling systems. We also discuss other methods for investigating the chromatin structure in cells. PMID:25168089

  14. Effect of Mg doping on the local structure of LiMgyCo1-yO2 cathode material investigated by X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, J. H.; Pan, C. J.; Nithya, C.; Thirunakaran, R.; Gopukumar, S.; Chen, C. H.; Lee, J. F.; Chen, J. M.; Sivashanmugam, A.; Hwang, B. J.

    2014-04-01

    A higher capacity and better cyclability are apparent when magnesium is introduced into the structure of LiCoO2 (y = 0.15). XRD analysis of LiMgyCo1-yO2 (y = 0, 0.1, 0.15), synthesized at 800 °C using a microwave assisted method, shows that the material is in the R-3m space group and to have a slightly expanded unit cell that increases with greater magnesium doping. Structural analysis by X-ray absorption spectroscopy (XAS) at the Co K-edge, L-edge and O K-edge shows that the magnesium is located in the transition metal layer rather than in the lithium layer and the charge balance results from the formation of oxygen vacancies rather than Co4+, while cobalt remains in the 3+ oxidation state. Interestingly, oxygen is found to participate in the charge compensation. Both magnesium, in the transition metal layer, and the Co-defect structure are attributed to the contribution towards structural stabilization of LiCoO2, thereby resulting in its enhanced electrochemical performance.

  15. Filtered cathodic arc source

    DOEpatents

    Falabella, S.; Sanders, D.M.

    1994-01-18

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge is described. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45[degree] to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles. 3 figures.

  16. Filtered cathodic arc source

    DOEpatents

    Falabella, Steven; Sanders, David M.

    1994-01-01

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45.degree. to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles.

  17. FUNCTION GENERATOR FOR ANALOGUE COMPUTERS

    DOEpatents

    Skramstad, H.K.; Wright, J.H.; Taback, L.

    1961-12-12

    An improved analogue computer is designed which can be used to determine the final ground position of radioactive fallout particles in an atomic cloud. The computer determines the fallout pattern on the basis of known wind velocity and direction at various altitudes, and intensity of radioactivity in the mushroom cloud as a function of particle size and initial height in the cloud. The output is then displayed on a cathode-ray tube so that the average or total luminance of the tube screen at any point represents the intensity of radioactive fallout at the geographical location represented by that point. (AEC)

  18. Object Specific Trajectory Optimization for Industrial X-ray Computed Tomography

    NASA Astrophysics Data System (ADS)

    Fischer, Andreas; Lasser, Tobias; Schrapp, Michael; Stephan, Jürgen; Noël, Peter B.

    2016-01-01

    In industrial settings, X-ray computed tomography scans are a common tool for inspection of objects. Often the object can not be imaged using standard circular or helical trajectories because of constraints in space or time. Compared to medical applications the variance in size and materials is much larger. Adapting the acquisition trajectory to the object is beneficial and sometimes inevitable. There are currently no sophisticated methods for this adoption. Typically the operator places the object according to his best knowledge. We propose a detectability index based optimization algorithm which determines the scan trajectory on the basis of a CAD-model of the object. The detectability index is computed solely from simulated projections for multiple user defined features. By adapting the features the algorithm is adapted to different imaging tasks. Performance of simulated and measured data was qualitatively and quantitatively assessed.The results illustrate that our algorithm not only allows more accurate detection of features, but also delivers images with high overall quality in comparison to standard trajectory reconstructions. This work enables to reduce the number of projections and in consequence scan time by introducing an optimization algorithm to compose an object specific trajectory.

  19. Detection of bacteria in porous media using x-ray computed micro tomography

    NASA Astrophysics Data System (ADS)

    Polak, A.; Landon, M.; Grader, A. S.; Elsworth, D.

    2003-04-01

    Results are reported on experiments to determine if bacteria containing naturally occurring magnetite or magnetite that had been conjugated to the bacteria could be detected with CMT (Computed Micro Tomography). In-situ monitoring was done on Magnetospirillum, microaerophillic bacteria containing magnetite particles (Fe_3O_4) that were successfully grown in the lab. The bacteria were scanned in MSGM revised medium with and without ferric quinate and in a sample of sand grains. In another experiment, monoclonal anti-E. coli antibody that was immobilized onto BSA coated ferromagnetite particles and mixed with an aliquot of x-ray resistant E. coli bacteria was used. The sample was scanned in solution and in a Berea rock sample. We found that the Magnetospirillum can be detected in the porous media if the concentration of the bacteria is high enough, as the amount of the magnetite particles inside the bacteria is small. In the second experiment, the tagged E. coli was detected in a solution and within the Berea sample using the Computed Micro Tomography.

  20. [Beam hardening correction method for X-ray computed tomography based on subsection beam hardening curves].

    PubMed

    Huang, Kui-dong; Zhang, Ding-hua

    2009-09-01

    After researching the forming principle of X-ray beam hardening and analyzing the usual methods of beam hardening correction, a beam hardening correction model was established, in which the independent variable was the projection gray, and so the computing difficulties in beam hardening correction can be reduced. By considering the advantage and disadvantage of fitting beam hardening curve to polynomial, a new expression method of the subsection beam hardening curves based on polynomial was proposed. In the method, the beam hardening data were fitted firstly to a polynomial curve which traverses the coordinate origin, then whether the got polynomial curve surged in the fore-part or back-part of the fitting range was judged based on the polynomial curvature change. If the polynomial fitting curve surged, the power function curve was applied to replace the surging parts of the polynomial curve, and the C1 continuity was ensured at the joints of the segment curves. The experimental results of computed tomography (CT) simulation show that the method is well stable in the beam hardening correction for the ideal CT images and CT images with added noises, and can mostly remove the beam hardening artifact at the same time.

  1. Breast tumor segmentation in high resolution x-ray phase contrast analyzer based computed tomography

    SciTech Connect

    Brun, E.; Grandl, S.; Sztrókay-Gaul, A.; Gasilov, S.; Barbone, G.; Mittone, A.; Coan, P.; Bravin, A.

    2014-11-01

    Purpose: Phase contrast computed tomography has emerged as an imaging method, which is able to outperform present day clinical mammography in breast tumor visualization while maintaining an equivalent average dose. To this day, no segmentation technique takes into account the specificity of the phase contrast signal. In this study, the authors propose a new mathematical framework for human-guided breast tumor segmentation. This method has been applied to high-resolution images of excised human organs, each of several gigabytes. Methods: The authors present a segmentation procedure based on the viscous watershed transform and demonstrate the efficacy of this method on analyzer based phase contrast images. The segmentation of tumors inside two full human breasts is then shown as an example of this procedure’s possible applications. Results: A correct and precise identification of the tumor boundaries was obtained and confirmed by manual contouring performed independently by four experienced radiologists. Conclusions: The authors demonstrate that applying the watershed viscous transform allows them to perform the segmentation of tumors in high-resolution x-ray analyzer based phase contrast breast computed tomography images. Combining the additional information provided by the segmentation procedure with the already high definition of morphological details and tissue boundaries offered by phase contrast imaging techniques, will represent a valuable multistep procedure to be used in future medical diagnostic applications.

  2. Reconstruction of sparse-view X-ray computed tomography using adaptive iterative algorithms.

    PubMed

    Liu, Li; Lin, Weikai; Jin, Mingwu

    2015-01-01

    In this paper, we propose two reconstruction algorithms for sparse-view X-ray computed tomography (CT). Treating the reconstruction problems as data fidelity constrained total variation (TV) minimization, both algorithms adapt the alternate two-stage strategy: projection onto convex sets (POCS) for data fidelity and non-negativity constraints and steepest descent for TV minimization. The novelty of this work is to determine iterative parameters automatically from data, thus avoiding tedious manual parameter tuning. In TV minimization, the step sizes of steepest descent are adaptively adjusted according to the difference from POCS update in either the projection domain or the image domain, while the step size of algebraic reconstruction technique (ART) in POCS is determined based on the data noise level. In addition, projection errors are used to compare with the error bound to decide whether to perform ART so as to reduce computational costs. The performance of the proposed methods is studied and evaluated using both simulated and physical phantom data. Our methods with automatic parameter tuning achieve similar, if not better, reconstruction performance compared to a representative two-stage algorithm.

  3. Object Specific Trajectory Optimization for Industrial X-ray Computed Tomography.

    PubMed

    Fischer, Andreas; Lasser, Tobias; Schrapp, Michael; Stephan, Jürgen; Noël, Peter B

    2016-01-28

    In industrial settings, X-ray computed tomography scans are a common tool for inspection of objects. Often the object can not be imaged using standard circular or helical trajectories because of constraints in space or time. Compared to medical applications the variance in size and materials is much larger. Adapting the acquisition trajectory to the object is beneficial and sometimes inevitable. There are currently no sophisticated methods for this adoption. Typically the operator places the object according to his best knowledge. We propose a detectability index based optimization algorithm which determines the scan trajectory on the basis of a CAD-model of the object. The detectability index is computed solely from simulated projections for multiple user defined features. By adapting the features the algorithm is adapted to different imaging tasks. Performance of simulated and measured data was qualitatively and quantitatively assessed.The results illustrate that our algorithm not only allows more accurate detection of features, but also delivers images with high overall quality in comparison to standard trajectory reconstructions. This work enables to reduce the number of projections and in consequence scan time by introducing an optimization algorithm to compose an object specific trajectory.

  4. Feasibility study of a high-spatial resolution x-ray computed tomography using sub-pixel shift method

    SciTech Connect

    Yoneyama, Akio Baba, Rika; Sumitani, Kazushi; Hirai, Yasuharu

    2015-02-23

    A high-spatial resolution X-ray computed tomography (CT) adopting a sub-pixel shift method has been developed. By calculating sectional images, using plural CT datasets obtained by scanning the X-ray imager, the spatial resolution can be reduced relative to the sub-pixel size of an X-ray imager. Feasibility observations of a biomedical sample were performed using 12-keV monochromatic synchrotron radiation and a photon-counting X-ray imager 174-μm pixels in size. Four CT measurements were performed to obtain datasets at different positions of the X-ray imager. Fine sectional images were obtained successfully, and the spatial resolution was estimated as 80-μm, which corresponds to just under half the pixel size of the imager. In addition, a fine 3D image was also obtained by scanning the imager two-dimensionally.

  5. Analytical computation of prompt gamma ray emission and detection for proton range verification

    NASA Astrophysics Data System (ADS)

    Sterpin, E.; Janssens, G.; Smeets, J.; Vander Stappen, François; Prieels, D.; Priegnitz, Marlen; Perali, Irene; Vynckier, S.

    2015-06-01

    A prompt gamma (PG) slit camera prototype recently demonstrated that Bragg Peak position in a clinical proton scanned beam could be measured with 1-2 mm accuracy by comparing an expected PG detection profile to a measured one. The computation of the expected PG detection profile in the context of a clinical framework is challenging but must be solved before clinical implementation. Obviously, Monte Carlo methods (MC) can simulate the expected PG profile but at prohibitively long calculation times. We implemented a much faster method that is based on analytical processing of precomputed MC data that would allow practical evaluation of this range monitoring approach in clinical conditions. Reference PG emission profiles were generated with MC simulations (PENH) in targets consisting of either 12C, 14N, 16O, 31P or 40Ca, with 10% of 1H. In a given geometry, the local PG emission can then be derived by adding the contribution of each element, according to the local energy of the proton obtained by continuous slowing down approximation and the local composition. The actual incident spot size is taken into account using an optical model fitted to measurements and by super sampling the spot with several rays (up to 113). PG transport in the patient/camera geometries and the detector response are modelled by convolving the PG production profile with a transfer function. The latter is interpolated from a database of transfer functions fitted to MC data (PENELOPE) generated for a photon source in a cylindrical phantom with various radiuses and a camera placed at various positions. As a benchmark, the analytical model was compared to MC and experiments in homogeneous and heterogeneous phantoms. Comparisons with MC were also performed in a thoracic CT. For all cases, the analytical model reproduced the prediction of the position of the Bragg peak computed with MC within 1 mm for the camera in nominal configuration. When compared to measurements, the shape of the profiles

  6. Analytical computation of prompt gamma ray emission and detection for proton range verification.

    PubMed

    Sterpin, E; Janssens, G; Smeets, J; Vander Stappen, François; Prieels, D; Priegnitz, Marlen; Perali, Irene; Vynckier, S

    2015-06-21

    A prompt gamma (PG) slit camera prototype recently demonstrated that Bragg Peak position in a clinical proton scanned beam could be measured with 1-2 mm accuracy by comparing an expected PG detection profile to a measured one. The computation of the expected PG detection profile in the context of a clinical framework is challenging but must be solved before clinical implementation. Obviously, Monte Carlo methods (MC) can simulate the expected PG profile but at prohibitively long calculation times. We implemented a much faster method that is based on analytical processing of precomputed MC data that would allow practical evaluation of this range monitoring approach in clinical conditions. Reference PG emission profiles were generated with MC simulations (PENH) in targets consisting of either (12)C, (14)N, (16)O, (31)P or (40)Ca, with 10% of (1)H. In a given geometry, the local PG emission can then be derived by adding the contribution of each element, according to the local energy of the proton obtained by continuous slowing down approximation and the local composition. The actual incident spot size is taken into account using an optical model fitted to measurements and by super sampling the spot with several rays (up to 113). PG transport in the patient/camera geometries and the detector response are modelled by convolving the PG production profile with a transfer function. The latter is interpolated from a database of transfer functions fitted to MC data (PENELOPE) generated for a photon source in a cylindrical phantom with various radiuses and a camera placed at various positions. As a benchmark, the analytical model was compared to MC and experiments in homogeneous and heterogeneous phantoms. Comparisons with MC were also performed in a thoracic CT. For all cases, the analytical model reproduced the prediction of the position of the Bragg peak computed with MC within 1 mm for the camera in nominal configuration. When compared to measurements, the shape of the

  7. Analytical computation of prompt gamma ray emission and detection for proton range verification.

    PubMed

    Sterpin, E; Janssens, G; Smeets, J; Vander Stappen, François; Prieels, D; Priegnitz, Marlen; Perali, Irene; Vynckier, S

    2015-06-21

    A prompt gamma (PG) slit camera prototype recently demonstrated that Bragg Peak position in a clinical proton scanned beam could be measured with 1-2 mm accuracy by comparing an expected PG detection profile to a measured one. The computation of the expected PG detection profile in the context of a clinical framework is challenging but must be solved before clinical implementation. Obviously, Monte Carlo methods (MC) can simulate the expected PG profile but at prohibitively long calculation times. We implemented a much faster method that is based on analytical processing of precomputed MC data that would allow practical evaluation of this range monitoring approach in clinical conditions. Reference PG emission profiles were generated with MC simulations (PENH) in targets consisting of either (12)C, (14)N, (16)O, (31)P or (40)Ca, with 10% of (1)H. In a given geometry, the local PG emission can then be derived by adding the contribution of each element, according to the local energy of the proton obtained by continuous slowing down approximation and the local composition. The actual incident spot size is taken into account using an optical model fitted to measurements and by super sampling the spot with several rays (up to 113). PG transport in the patient/camera geometries and the detector response are modelled by convolving the PG production profile with a transfer function. The latter is interpolated from a database of transfer functions fitted to MC data (PENELOPE) generated for a photon source in a cylindrical phantom with various radiuses and a camera placed at various positions. As a benchmark, the analytical model was compared to MC and experiments in homogeneous and heterogeneous phantoms. Comparisons with MC were also performed in a thoracic CT. For all cases, the analytical model reproduced the prediction of the position of the Bragg peak computed with MC within 1 mm for the camera in nominal configuration. When compared to measurements, the shape of the

  8. Cathode material for electrochemical cells

    SciTech Connect

    Ryan, D.M.

    1993-08-24

    A primary cell is described having an anode material, an electrolyte material and a cathode material, wherein said cathode material, in the predischarge condition thereof, is K[sub 3]V[sub 5]O[sub 14].

  9. Miniaturized cathodic arc plasma source

    DOEpatents

    Anders, Andre; MacGill, Robert A.

    2003-04-15

    A cathodic arc plasma source has an anode formed of a plurality of spaced baffles which extend beyond the active cathode surface of the cathode. With the open baffle structure of the anode, most macroparticles pass through the gaps between the baffles and reflect off the baffles out of the plasma stream that enters a filter. Thus the anode not only has an electrical function but serves as a prefilter. The cathode has a small diameter, e.g. a rod of about 1/4 inch (6.25 mm) diameter. Thus the plasma source output is well localized, even with cathode spot movement which is limited in area, so that it effectively couples into a miniaturized filter. With a small area cathode, the material eroded from the cathode needs to be replaced to maintain plasma production. Therefore, the source includes a cathode advancement or feed mechanism coupled to cathode rod. The cathode also requires a cooling mechanism. The movable cathode rod is housed in a cooled metal shield or tube which serves as both a current conductor, thus reducing ohmic heat produced in the cathode, and as the heat sink for heat generated at or near the cathode. Cooling of the cathode housing tube is done by contact with coolant at a place remote from the active cathode surface. The source is operated in pulsed mode at relatively high currents, about 1 kA. The high arc current can also be used to operate the magnetic filter. A cathodic arc plasma deposition system using this source can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  10. Analytical investigation of efficiency and performance limits in klystron amplifiers using multidimensional computer programs; multi-stage depressed collectors; and thermionic cathode life studies

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G.

    1980-01-01

    An extensive parametric investigation was performed of the extraction of energy in output gaps of klystron amplifiers, using 3-D computer programs. Due to complexity of the program which used a hydrodynamic, axially and radially deformable disk ring model and the resulting long computing time, the investigation was limited to the output gap, by far the most important and difficult part of the klystron interaction. Results show that, for a confined flow focused beam throughout the penultimate cavity, radial velocities remain very small and the beam is highly laminar. It was, therefore, concluded that possible errors resulting from treating only the output cavity in 3-D would remain small.

  11. Analytic investigation of efficiency and performance limits in klystron amplifiers using multidimensional computer programs; multi-stage depressed collectors; and thermionic cathode life studies

    NASA Technical Reports Server (NTRS)

    Kosmahl, H. G.

    1980-01-01

    Due to complexity of the program which used a hydrodynamic, axially and radially deformable disk-ring model and the resulting long computing time only the output gap was investigated. Results from independent studies were used to initiate the starting conditions for the electrons and the RF voltage using our program. Although this method of computation is less exact than processing the entire klystron interaction in 3-Dimensions it is shown that, for a confined flow focused throughout the penultimate cavity, radial velocities remain very small and the beam is highly laminar. It is concluded that possible errors resulting from treating only the output cavity in 3-D would remain small.

  12. Cathode material for lithium batteries

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2013-07-23

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  13. Cathode material for lithium batteries

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2015-01-13

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  14. Computer-aided diagnosis of pulmonary diseases using x-ray darkfield radiography

    NASA Astrophysics Data System (ADS)

    Einarsdóttir, Hildur; Yaroshenko, Andre; Velroyen, Astrid; Bech, Martin; Hellbach, Katharina; Auweter, Sigrid; Yildirim, Önder; Meinel, Felix G.; Eickelberg, Oliver; Reiser, Maximilian; Larsen, Rasmus; Kjær Ersbøll, Bjarne; Pfeiffer, Franz

    2015-12-01

    In this work we develop a computer-aided diagnosis (CAD) scheme for classification of pulmonary disease for grating-based x-ray radiography. In addition to conventional transmission radiography, the grating-based technique provides a dark-field imaging modality, which utilizes the scattering properties of the x-rays. This modality has shown great potential for diagnosing early stage emphysema and fibrosis in mouse lungs in vivo. The CAD scheme is developed to assist radiologists and other medical experts to develop new diagnostic methods when evaluating grating-based images. The scheme consists of three stages: (i) automatic lung segmentation; (ii) feature extraction from lung shape and dark-field image intensities; (iii) classification between healthy, emphysema and fibrosis lungs. A study of 102 mice was conducted with 34 healthy, 52 emphysema and 16 fibrosis subjects. Each image was manually annotated to build an experimental dataset. System performance was assessed by: (i) determining the quality of the segmentations; (ii) validating emphysema and fibrosis recognition by a linear support vector machine using leave-one-out cross-validation. In terms of segmentation quality, we obtained an overlap percentage (Ω) 92.63  ±  3.65%, Dice Similarity Coefficient (DSC) 89.74  ±  8.84% and Jaccard Similarity Coefficient 82.39  ±  12.62%. For classification, the accuracy, sensitivity and specificity of diseased lung recognition was 100%. Classification between emphysema and fibrosis resulted in an accuracy of 93%, whilst the sensitivity was 94% and specificity 88%. In addition to the automatic classification of lungs, deviation maps created by the CAD scheme provide a visual aid for medical experts to further assess the severity of pulmonary disease in the lung, and highlights regions affected.

  15. X-ray scatter correction method for dedicated breast computed tomography: improvements and initial patient testing

    NASA Astrophysics Data System (ADS)

    Ramamurthy, Senthil; D'Orsi, Carl J.; Sechopoulos, Ioannis

    2016-02-01

    A previously proposed x-ray scatter correction method for dedicated breast computed tomography was further developed and implemented so as to allow for initial patient testing. The method involves the acquisition of a complete second set of breast CT projections covering 360° with a perforated tungsten plate in the path of the x-ray beam. To make patient testing feasible, a wirelessly controlled electronic positioner for the tungsten plate was designed and added to a breast CT system. Other improvements to the algorithm were implemented, including automated exclusion of non-valid primary estimate points and the use of a different approximation method to estimate the full scatter signal. To evaluate the effectiveness of the algorithm, evaluation of the resulting image quality was performed with a breast phantom and with nine patient images. The improvements in the algorithm resulted in the avoidance of introduction of artifacts, especially at the object borders, which was an issue in the previous implementation in some cases. Both contrast, in terms of signal difference and signal difference-to-noise ratio were improved with the proposed method, as opposed to with the correction algorithm incorporated in the system, which does not recover contrast. Patient image evaluation also showed enhanced contrast, better cupping correction, and more consistent voxel values for the different tissues. The algorithm also reduces artifacts present in reconstructions of non-regularly shaped breasts. With the implemented hardware and software improvements, the proposed method can be reliably used during patient breast CT imaging, resulting in improvement of image quality, no introduction of artifacts, and in some cases reduction of artifacts already present. The impact of the algorithm on actual clinical performance for detection, diagnosis and other clinical tasks in breast imaging remains to be evaluated.

  16. DEVELOPMENTS IN SYNCHROTRON X-RAY COMPUTED MICROTOMOGRAPHY AT THE NATIONAL SYNCHROTRON LIGHT SOURCE.

    SciTech Connect

    DOWD,B.A.

    1999-07-23

    Last year, the X27A beamline at the National Synchrotron Light Source (NSLS) became dedicated solely to X-Ray Computed Microtomography (XCMT). This is a third-generation instrument capable of producing tomographic volumes of 1-2 micron resolution over a 2-3mm field of view. Recent enhancements will be discussed. These have focused on two issues: the desire for real-time data acquisition and processing and the need for highly monochromatic beam (.1 % energy bandpass). The latter will permit k-edge subtraction studies and will provide improved image contrast from below the Cr (6 keV) up to the Cs (36 keV) k-edge. A range of applications that benefit from these improvements will be discussed as well. These two goals are somewhat counterproductive, however; higher monochromaticity yields a lower flux forcing longer data acquisition times. To balance the two, a more efficient scintillator for X-ray conversion is being developed. Some testing of a prototype scintillator has been performed; preliminary results will be presented here. In the meantime, data reconstruction times have been reduced, and the entire tomographic acquisition, reconstruction and volume rendering process streamlined to make efficient use of synchrotron beam time. A Fast Filtered Back Transform (FFBT) reconstruction program recently developed helped to reduce the time to reconstruct a volume of 150 x 150 x 250 pixels{sup 3} (over 5 million voxels) from the raw camera data to 1.5 minutes on a dual R10,000 CPU. With these improvements, one can now obtain a ''quick look'' of a small tomographic volume ({approximately}10{sup 6}voxels) in just over 15 minutes from the start of data acquisition.

  17. Microstructural analysis of TRISO particles using multi-scale X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Lowe, T.; Bradley, R. S.; Yue, S.; Barii, K.; Gelb, J.; Rohbeck, N.; Turner, J.; Withers, P. J.

    2015-06-01

    TRISO particles, a composite nuclear fuel built up by ceramic and graphitic layers, have outstanding high temperature resistance. TRISO fuel is the key technology for High Temperature Reactors (HTRs) and the Generation IV Very High Temperature Reactor (VHTR) variant. TRISO offers unparalleled containment of fission products and is extremely robust during accident conditions. An understanding of the thermal performance and mechanical properties of TRISO fuel requires a detailed knowledge of pore sizes, their distribution and interconnectivity. Here 50 nm, nano-, and 1 μm resolution, micro-computed tomography (CT), have been used to quantify non-destructively porosity of a surrogate TRISO particle at the 0.3-10 μm and 3-100 μm scales respectively. This indicates that pore distributions can reliably be measured down to a size approximately 3 times the pixel size which is consistent with the segmentation process. Direct comparison with Scanning Electron Microscopy (SEM) sections indicates that destructive sectioning can introduce significant levels of coarse damage, especially in the pyrolytic carbon layers. Further comparative work is required to identify means of minimizing such damage for SEM studies. Finally since it is non-destructive, multi-scale time-lapse X-ray CT opens the possibility of intermittently tracking the degradation of TRISO structure under thermal cycles or radiation conditions in order to validate models of degradation such as kernel movement. X-ray CT in-situ experimentation of TRISO particles under load and temperature could also be used to understand the internal changes that occur in the particles under accident conditions.

  18. Imaging biofilms in porous media using X-ray computed micro-tomography

    NASA Astrophysics Data System (ADS)

    Davit, Y.; Debenest, G.; Quintard, M.

    2009-12-01

    In soils and rivers subsurface, bacterial biofilms growth induce modifications of mass and momentum transport dynamics. Evidence for these modifications have been developed essentially by inspection, that is, observation of the reduction of hydraulic conductivity, permeability, changes in porosity and anomalous transport. Deeper understanding of these sessile communities in porous media environments and of the multiscale/multiphase complexity of the system requires 3-D informations concerning the pore-scale/biofilm-scale geometry. Additionnally, breakthroughs in imaging techniques are likely to trigger breakthroughs in the theoretical analysis. In this study, we develop a new technique for direct observation and imaging of unstrained biofilms in porous media using X-ray computed micro-tomography. The biofilms are grown for ten days on polyamide and expanded polystyrene beads placed in small plastic columns. A circulation of water from the river Garonne (France) is imposed using peristaltic pumps. No particular bacterial strain is introduced, the micro-organisms being naturally present in the water from the river. The X-ray acquisition is performed by a Skyscan-1174 micro-CT. A special experimental technique, based on two different contrast agents, has been designed to solve the challenging problem of imaging 3 phases of initial similar absorption coefficients. On the one hand, we use a suspension of barium sulfate to enhance the contrast of the water-phase. On the other hand, the absorption of the biofilm-phase is increased using iodine which diffuses into the polymeric matrix. Examples of reconstructed images are given to illustrate the effectiveness of the method. We demonstrate how to combine the 3-D measurements with upscaling techniques such as volume averaging, by calculating the modifications of the permeability of the system when biofilms grow. At last, we aim to couple these 3-D measurements with upscaled reactive models to describe the Darcy

  19. Computer-aided recognition of dental implants in X-ray images

    NASA Astrophysics Data System (ADS)

    Morais, Pedro; Queirós, Sandro; Moreira, António H. J.; Ferreira, Adriano; Ferreira, Ernesto; Duque, Duarte; Rodrigues, Nuno F.; Vilaça, João. L.

    2015-03-01

    Dental implant recognition in patients without available records is a time-consuming and not straightforward task. The traditional method is a complete user-dependent process, where the expert compares a 2D X-ray image of the dental implant with a generic database. Due to the high number of implants available and the similarity between them, automatic/semi-automatic frameworks to aide implant model detection are essential. In this study, a novel computer-aided framework for dental implant recognition is suggested. The proposed method relies on image processing concepts, namely: (i) a segmentation strategy for semi-automatic implant delineation; and (ii) a machine learning approach for implant model recognition. Although the segmentation technique is the main focus of the current study, preliminary details of the machine learning approach are also reported. Two different scenarios are used to validate the framework: (1) comparison of the semi-automatic contours against implant's manual contours of 125 X-ray images; and (2) classification of 11 known implants using a large reference database of 601 implants. Regarding experiment 1, 0.97±0.01, 2.24±0.85 pixels and 11.12±6 pixels of dice metric, mean absolute distance and Hausdorff distance were obtained, respectively. In experiment 2, 91% of the implants were successfully recognized while reducing the reference database to 5% of its original size. Overall, the segmentation technique achieved accurate implant contours. Although the preliminary classification results prove the concept of the current work, more features and an extended database should be used in a future work.

  20. X-ray scatter correction method for dedicated breast computed tomography: improvements and initial patient testing.

    PubMed

    Ramamurthy, Senthil; D'Orsi, Carl J; Sechopoulos, Ioannis

    2016-02-01

    A previously proposed x-ray scatter correction method for dedicated breast computed tomography was further developed and implemented so as to allow for initial patient testing. The method involves the acquisition of a complete second set of breast CT projections covering 360° with a perforated tungsten plate in the path of the x-ray beam. To make patient testing feasible, a wirelessly controlled electronic positioner for the tungsten plate was designed and added to a breast CT system. Other improvements to the algorithm were implemented, including automated exclusion of non-valid primary estimate points and the use of a different approximation method to estimate the full scatter signal. To evaluate the effectiveness of the algorithm, evaluation of the resulting image quality was performed with a breast phantom and with nine patient images. The improvements in the algorithm resulted in the avoidance of introduction of artifacts, especially at the object borders, which was an issue in the previous implementation in some cases. Both contrast, in terms of signal difference and signal difference-to-noise ratio were improved with the proposed method, as opposed to with the correction algorithm incorporated in the system, which does not recover contrast. Patient image evaluation also showed enhanced contrast, better cupping correction, and more consistent voxel values for the different tissues. The algorithm also reduces artifacts present in reconstructions of non-regularly shaped breasts. With the implemented hardware and software improvements, the proposed method can be reliably used during patient breast CT imaging, resulting in improvement of image quality, no introduction of artifacts, and in some cases reduction of artifacts already present. The impact of the algorithm on actual clinical performance for detection, diagnosis and other clinical tasks in breast imaging remains to be evaluated. PMID:26760295

  1. MAX--An Interactive Computer Program for Teaching Identification of Clay Minerals by X-ray Diffraction.

    ERIC Educational Resources Information Center

    Kohut, Connie K.; And Others

    1993-01-01

    Discusses MAX, an interactive computer program for teaching identification of clay minerals based on standard x-ray diffraction characteristics. The program provides tutorial-type exercises for identification of 16 clay standards, self-evaluation exercises, diffractograms of 28 soil clay minerals, and identification of nonclay minerals. (MDH)

  2. Model of the plasma jet originating from a cathode spot

    SciTech Connect

    Gavrilov, V.N.; Litvinov, E.A.; Mesyats, G.A.

    1995-12-31

    The 2-D NM model of the vacuum-arc plasma jet presented here is in outgrowth of the 1-D hydrodynamic model discussed by us. The computation carried out in 1-D approximation have provided the principal characteristics of a cathode jet being in satisfactory agreement with experimental data. Nevertheless, there results cannot be considered completely adequate, since actually the plum parameters of a cathode jet are distributed highly nonuniformly over its cross section. Furthermore, a 1-D model falls to take in to account the effects related to the influence of the self-magnetic field of the cathode jet.

  3. Characterization of impact damage in metallic/nonmetallic composites using x-ray computed tomography imaging

    NASA Astrophysics Data System (ADS)

    Green, William H.; Wells, Joseph M.

    1999-12-01

    Characterizing internal impact damage in composites can be difficult, especially in structurally complex composites or those consisting of many materials. Many methods for nondestructive inspection/nondestructive testing (NDI/NDT) of materials have been known and in use for many years, including x-ray film, real-time, and digital radiographic techniques, and ultrasonic techniques. However, these techniques are generally not capable of three-dimensional (3D) mapping of complex damage patterns, which is necessary to visualize and understand damage cracking modes. Conventional x-ray radiography suffers from the loss of 3D information. Structural complexity and signal dispersion in materials with many interfaces significantly effect ultrasonic inspection techniques. This makes inspection scan interpretation difficult, especially in composites containing a number of different materials (i.e., polymer, ceramic, and metallic). X-ray computed tomography (CT) is broadly applicable to any material or test object through which a beam of penetrating radiation may be passed and detected, including metals, plastics, ceramics, metallic/nonmetallic composites, and assemblies. The principal advantage of CT is that it provides densitometric (that is, radiological density and geometry) images of thin cross sections through an object. Because of the absence of structural superposition, images are much easier to interpret than conventional radiological images. The user can quickly learn to read CT data because images correspond more closely to the way the human mind visualizes 3D structures than projection radiology (that is, film radiography, real-time radiography (RTR), and digital radiography (DR)). Any number of CT images, or slices, from scanning an object can be volumetrically reconstructed to produce a 3D attenuation map of the object. The 3D attenuation data can be rendered using multiplanar or 3D solid visualization. In multiplanar visualization there are four planes of view

  4. Development of Kilovoltage X-ray Dosimetry Methods and Their Application to Cone Beam Computed Tomography

    NASA Astrophysics Data System (ADS)

    Lawless, Michael J.

    The increase in popularity of pre-treatment imaging procedures in radiation therapy, such as kilovoltage cone beam computed tomography (CBCT), has been accompanied by an increase in the dose delivered to the patient from these imaging procedures. The measurement of dose from CBCT scans is complicated, as currently available kilovoltage dosimetry protocols are based on air-kerma standards and radiation detectors exhibit large energy responses at the low photon energies used in the imaging procedures. This work aims to provide the tools and methodology needed to measure the dose from these scans more accurately and precisely. Through the use of a validated Monte Carlo (MC) model of the moderately filtered (M-series) x-ray beams at the University of Wisconsin Accredited Dosimetry Calibration Laboratory, dose-to-water rates were obtained in a water phantom for the M-series x-ray beams with tube potentials from 40-250 kVp. The resulting dose-to-water rates were consistent with previously established methods, but had significantly reduced uncertainties. While detectors are commonly used to measure dose in phantom, previous investigations of the energy response of common detectors in the kilovoltage energy range have been limited to in-air geometries. The newly determined dose-to-water rates were used to characterize the in-phantom energy and depth response of thermoluminescent dosimeters and ionization chambers. When compared to previous investigations of the in-air detector response, the impact of scatter and absorption of the photon beam by the water medium was found to have a significant impact on the response of certain detectors. The dose to water in the NIST-traceable M-series x-ray beams was transferred to clinical CBCT beams and the resulting doses agreed with other dose-to-water measurement techniques. The dose to water in the CBCT beams was used to characterize the energy and depth responses of a number of detectors. The energy response in the CBCT beams agreed

  5. THE SAP3 COMPUTER PROGRAM FOR QUANTITATIVE MULTIELEMENT ANALYSIS BY ENERGY DISPERSIVE X-RAY FLUORESCENCE

    SciTech Connect

    Nielson, K. K.; Sanders, R. W.

    1982-04-01

    SAP3 is a dual-function FORTRAN computer program which performs peak analysis of energy-dispersive x-ray fluorescence spectra and then quantitatively interprets the results of the multielement analysis. It was written for mono- or bi-chromatic excitation as from an isotopic or secondary excitation source, and uses the separate incoherent and coherent backscatter intensities to define the bulk sample matrix composition. This composition is used in performing fundamental-parameter matrix corrections for self-absorption, enhancement, and particle-size effects, obviating the need for specific calibrations for a given sample matrix. The generalized calibration is based on a set of thin-film sensitivities, which are stored in a library disk file and used for all sample matrices and thicknesses. Peak overlap factors are also determined from the thin-film standards, and are stored in the library for calculating peak overlap corrections. A detailed description is given of the algorithms and program logic, and the program listing and flow charts are also provided. An auxiliary program, SPCAL, is also given for use in calibrating the backscatter intensities. SAP3 provides numerous analysis options via seventeen control switches which give flexibility in performing the calculations best suited to the sample and the user needs. User input may be limited to the name of the library, the analysis livetime, and the spectrum filename and location. Output includes all peak analysis information, matrix correction factors, and element concentrations, uncertainties and detection limits. Twenty-four elements are typically determined from a 1024-channel spectrum in one-to-two minutes using a PDP-11/34 computer operating under RSX-11M.

  6. Computer-Controlled Cylindrical Polishing Process for Large X-Ray Mirror Mandrels

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    We are developing high-energy grazing incidence shell optics for hard-x-ray telescopes. The resolution of a mirror shells depends on the quality of cylindrical mandrel from which they are being replicated. Mid-spatial-frequency axial figure error is a dominant contributor in the error budget of the mandrel. This paper presents our efforts to develop a deterministic cylindrical polishing process in order to keep the mid-spatial-frequency axial figure errors to a minimum. Simulation software is developed to model the residual surface figure errors of a mandrel due to the polishing process parameters and the tools used, as well as to compute the optical performance of the optics. The study carried out using the developed software was focused on establishing a relationship between the polishing process parameters and the mid-spatial-frequency error generation. The process parameters modeled are the speeds of the lap and the mandrel, the tool s influence function, the contour path (dwell) of the tools, their shape and the distribution of the tools on the polishing lap. Using the inputs from the mathematical model, a mandrel having conical approximated Wolter-1 geometry, has been polished on a newly developed computer-controlled cylindrical polishing machine. The preliminary results of a series of polishing experiments demonstrate a qualitative agreement with the developed model. We report our first experimental results and discuss plans for further improvements in the polishing process. The ability to simulate the polishing process is critical to optimize the polishing process, improve the mandrel quality and significantly reduce the cost of mandrel production

  7. Assessment of different computational models for generation of x-ray spectra in diagnostic radiology and mammography

    SciTech Connect

    Ay, M.R.; Sarkar, S.; Shahriari, M.; Sardari, D.; Zaidi, H.

    2005-06-15

    Different computational methods based on empirical or semi-empirical models and sophisticated Monte Carlo calculations have been proposed for prediction of x-ray spectra both in diagnostic radiology and mammography. In this work, the x-ray spectra predicted by various computational models used in the diagnostic radiology and mammography energy range have been assessed by comparison with measured spectra and their effect on the calculation of absorbed dose and effective dose (ED) imparted to the adult ORNL hermaphroditic phantom quantified. This includes empirical models (TASMIP and MASMIP), semi-empirical models (X-rayb and m, X-raytbc, XCOMP, IPEM, Tucker et al., and Blough et al.), and Monte Carlo modeling (EGS4, ITS3.0, and MCNP4C). As part of the comparative assessment, the K x-ray yield, transmission curves, and half value layers (HVLs) have been calculated for the spectra generated with all computational models at different tube voltages. The measured x-ray spectra agreed well with the generated spectra when using X-raytbc and IPEM in diagnostic radiology and mammography energy ranges, respectively. Despite the systematic differences between the simulated and reference spectra for some models, the student's t-test statistical analysis showed there is no statistically significant difference between measured and generated spectra for all computational models investigated in this study. The MCNP4C-based Monte Carlo calculations showed there is no discernable discrepancy in the calculation of absorbed dose and ED in the adult ORNL hermaphroditic phantom when using different computational models for generating the x-ray spectra. Nevertheless, given the limited flexibility of the empirical and semi-empirical models, the spectra obtained through Monte Carlo modeling offer several advantages by providing detailed information about the interactions in the target and filters, which is relevant for the design of new target and filter combinations and optimization of

  8. Hydrogen hollow cathode ion source

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J., Jr.; Sovey, J. S.; Roman, R. F. (Inventor)

    1980-01-01

    A source of hydrogen ions is disclosed and includes a chamber having at one end a cathode which provides electrons and through which hydrogen gas flows into the chamber. Screen and accelerator grids are provided at the other end of the chamber. A baffle plate is disposed between the cathode and the grids and a cylindrical baffle is disposed coaxially with the cathode at the one end of the chamber. The cylindrical baffle is of greater diameter than the baffle plate to provide discharge impedance and also to protect the cathode from ion flux. An anode electrode draws the electrons away from the cathode. The hollow cathode includes a tubular insert of tungsten impregnated with a low work function material to provide ample electrons. A heater is provided around the hollow cathode to initiate electron emission from the low work function material.

  9. Synopsis of Cathode #4 Activation

    SciTech Connect

    Kwan, Joe; Ekdahl, C.; Harrison, J.; Kwan, J.; Leitner, M.; McCruistian, T.; Mitchell, R.; Prichard, B.; Roy, P.

    2006-05-26

    The purpose of this report is to describe the activation of the fourth cathode installed in the DARHT-II Injector. Appendices have been used so that an extensive amount of data could be included without danger of obscuring important information contained in the body of the report. The cathode was a 612 M type cathode purchased from Spectra-Mat. Section II describes the handling and installation of the cathode. Section III is a narrative of the activation based on information located in the Control Room Log Book supplemented with time plots of pertinent operating parameters. Activation of the cathode was performed in accordance with the procedure listed in Appendix A. The following sections provide more details on the total pressure and constituent partial pressures in the vacuum vessel, cathode heater power/filament current, and cathode temperature.

  10. Multicontrast x-ray computed tomography imaging using Talbot-Lau interferometry without phase stepping

    SciTech Connect

    Bevins, Nicholas; Zambelli, Joseph; Li Ke; Qi Zhihua; Chen Guanghong

    2012-01-15

    Purpose: The purpose of this work is to demonstrate that multicontrast computed tomography (CT) imaging can be performed using a Talbot-Lau interferometer without phase stepping, thus allowing for an acquisition scheme like that used for standard absorption CT. Methods: Rather than using phase stepping to extract refraction, small-angle scattering (SAS), and absorption signals, the two gratings of a Talbot-Lau interferometer were rotated slightly to generate a moire pattern on the detector. A Fourier analysis of the moire pattern was performed to obtain separate projection images of each of the three contrast signals, all from the same single-shot of x-ray exposure. After the signals were extracted from the detector data for all view angles, image reconstruction was performed to obtain absorption, refraction, and SAS CT images. A physical phantom was scanned to validate the proposed data acquisition method. The results were compared with a phantom scan using the standard phase stepping approach. Results: The reconstruction of each contrast mechanism produced the expected results. Signal levels and contrasts match those obtained using the phase stepping technique. Conclusions: Absorption, refraction, and SAS CT imaging can be achieved using the Talbot-Lau interferometer without the additional overhead of long scan time and phase stepping.

  11. Volumetric characterization of human patellar cartilage matrix on phase contrast x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Abidin, Anas Z.; Nagarajan, Mahesh B.; Checefsky, Walter A.; Coan, Paola; Diemoz, Paul C.; Hobbs, Susan K.; Huber, Markus B.; Wismüller, Axel

    2015-03-01

    Phase contrast X-ray computed tomography (PCI-CT) has recently emerged as a novel imaging technique that allows visualization of cartilage soft tissue, subsequent examination of chondrocyte patterns, and their correlation to osteoarthritis. Previous studies have shown that 2D texture features are effective at distinguishing between healthy and osteoarthritic regions of interest annotated in the radial zone of cartilage matrix on PCI-CT images. In this study, we further extend the texture analysis to 3D and investigate the ability of volumetric texture features at characterizing chondrocyte patterns in the cartilage matrix for purposes of classification. Here, we extracted volumetric texture features derived from Minkowski Functionals and gray-level co-occurrence matrices (GLCM) from 496 volumes of interest (VOI) annotated on PCI-CT images of human patellar cartilage specimens. The extracted features were then used in a machine-learning task involving support vector regression to classify ROIs as healthy or osteoarthritic. Classification performance was evaluated using the area under the receiver operating characteristic (ROC) curve (AUC). The best classification performance was observed with GLCM features correlation (AUC = 0.83 +/- 0.06) and homogeneity (AUC = 0.82 +/- 0.07), which significantly outperformed all Minkowski Functionals (p < 0.05). These results suggest that such quantitative analysis of chondrocyte patterns in human patellar cartilage matrix involving GLCM-derived statistical features can distinguish between healthy and osteoarthritic tissue with high accuracy.

  12. Computer simulations of X-ray six-beam diffraction in a perfect silicon crystal. I.

    PubMed

    Kohn, V G; Khikhlukha, D R

    2016-05-01

    This paper reports computer simulations of the transmitted-beam intensity distribution for the case of six-beam (000, 220, 242, 044, -224, -202) diffraction of X-rays in a perfect silicon crystal of thickness 1 mm. Both the plane-wave angular dependence and the six-beam section topographs, which are usually obtained in experiments with a restricted beam (two-dimensional slit), are calculated. The angular dependence is calculated in accordance with Ewald's theory. The section topographs are calculated from the angular dependence by means of the fast Fourier transformation procedure. This approach allows one to consider, for the first time, the transformation of the topograph's structure due to the two-dimensional slit sizes and the distance between the slit and the detector. The results are in good agreement with the results of other works and with the experimental data. This method of calculation does not require a supercomputer and it was performed on a standard laptop. A detailed explanation of the main features of the diffraction patterns at different distances between the slit and the detector is presented. PMID:27126111

  13. Data fusion in X-ray computed tomography using a superiorization approach

    SciTech Connect

    Schrapp, Michael J.; Herman, Gabor T.

    2014-05-15

    X-ray computed tomography (CT) is an important and widespread inspection technique in industrial non-destructive testing. However, large-sized and heavily absorbing objects cause artifacts due to either the lack of penetration of the specimen in specific directions or by having data from only a limited angular range of views. In such cases, valuable information about the specimen is not revealed by the CT measurements alone. Further imaging modalities, such as optical scanning and ultrasonic testing, are able to provide data (such as an edge map) that are complementary to the CT acquisition. In this paper, a superiorization approach (a newly developed method for constrained optimization) is used to incorporate the complementary data into the CT reconstruction; this allows precise localization of edges that are not resolvable from the CT data by itself. Superiorization, as presented in this paper, exploits the fact that the simultaneous algebraic reconstruction technique (SART), often used for CT reconstruction, is resilient to perturbations; i.e., it can be modified to produce an output that is as consistent with the CT measurements as the output of unmodified SART, but is more consistent with the complementary data. The application of this superiorized SART method to measured data of a turbine blade demonstrates a clear improvement in the quality of the reconstructed image.

  14. Particle induced X-ray emission-computed tomography analysis of an adsorbent for extraction chromatography

    NASA Astrophysics Data System (ADS)

    Satoh, Takahiro; Yokoyama, Akihito; Kitamura, Akane; Ohkubo, Takeru; Ishii, Yasuyuki; Takahatake, Yoko; Watanabe, Sou; Koma, Yoshikazu; Kada, Wataru

    2016-03-01

    Nd, which simulates minor actinides (MAs), was used for investigating residual minor actinides produced during the extraction chromatography separation of spent fuel from fast neutron reactors. A cross-sectional distribution of Nd in a minute globular adsorbent having diameter less than 50 μm was obtained using particle induced X-ray emission-computed tomography with a 3-MeV proton microbeam. The measurement area was 150 × 150 μm2 corresponding to 128 × 128 imaging pixels in projection images with 9° resolution, image reconstruction was carried out by a modified ML-EM (maximum likelihood expectation maximization) method. As a result, the cross-sectional distribution of Nd in the adsorbent was successfully obtained, and it was first revealed that Nd existed both in the central region and on the outer surface even after an elution. This implies that the internal structure of the adsorbent must be modified for improving of the recovery of MAs.

  15. Imaging of sand production in horizontal packs by x-ray computed tomography

    SciTech Connect

    Tremblay, B.; Sedgwick, G.; Forshner, K.

    1995-12-31

    Production rates for wells in the Cold Lake area of Alberta that are on {open_quotes}coldflow{close_quotes} production can be much higher than expected from estimates based on radial Darcy flow. Coldflow production here refers to a recovery process used in unconsolidated heavy oil reservoirs in which sand and oil are produced together under primary conditions. A laboratory experiment was designed to model sand production into a perforation in a vertical well drilled into the heavy oil formation. In this experiment, heavy oil (21,500 cP) flowed through a horizontal sand pack and into an orifice simulating a perforation. The flowing oil induced the co-production of sand from the pack when the pressure gradient at the orifice reached 33 Mpa/cm. The sand pack was scanned using X-ray computed tomography (CT). The CT images revealed that a high permeability circular channel (wormhole) had formed in the pack while sand was being produced. The wormhole followed the regions within the sand pack where the porosity was higher and consequently the compressive strength was lower. The porosity within the wormhole was much higher (55%) than the porosity within the undisturbed sand pack (32 %). No significant fines migration was observed before sand production occurred. The particle size distribution of the produced sand was the same as that remaining within the wormhole.

  16. X-ray computed tomography imaging: A not-so-nondestructive technique

    NASA Astrophysics Data System (ADS)

    Sears, Derek W. G.; Sears, Hazel; Ebel, Denton S.; Wallace, Sean; Friedrich, Jon M.

    2016-04-01

    X-ray computed tomography has become a popular means for examining the interiors of meteorites and has been advocated for routine curation and for the examination of samples returned by missions. Here, we report the results of a blind test that indicate that CT imaging deposits a considerable radiation dose in a meteorite and seriously compromises its natural radiation record. Ten vials of the Bruderheim L6 chondrite were placed in CT imager and exposed to radiation levels typical for meteorite studies. Half were retained as controls. Their thermoluminescence (TL) properties were then measured in a blind test. Five of the samples had TL data unaltered from their original (~10 cps) while five had very strong signals (~20,000 cps). It was therefore very clear which samples had been in the CT scanner. For comparison, the natural TL signal from Antarctic meteorites is ~5000-50,000 cps. Using the methods developed for Antarctic meteorites, the apparent dose absorbed by the five test samples was calculated to be 83 ± 5 krad, comparable with the highest doses observed in Antarctic meteorites and freshly fallen meteorites. While these results do not preclude the use of CT scanners when scientifically justified, it should be remembered that the record of radiation exposure to ionizing radiations for the sample will be destroyed and that TL, or the related optically stimulated luminescence, are the primary modern techniques for radiation dosimetry. This is particularly important with irreplaceable samples, such as meteorite main masses, returned samples, and samples destined for archive.

  17. A reconstruction method for cone-beam differential x-ray phase-contrast computed tomography.

    PubMed

    Fu, Jian; Velroyen, Astrid; Tan, Renbo; Zhang, Junwei; Chen, Liyuan; Tapfer, Arne; Bech, Martin; Pfeiffer, Franz

    2012-09-10

    Most existing differential phase-contrast computed tomography (DPC-CT) approaches are based on three kinds of scanning geometries, described by parallel-beam, fan-beam and cone-beam. Due to the potential of compact imaging systems with magnified spatial resolution, cone-beam DPC-CT has attracted significant interest. In this paper, we report a reconstruction method based on a back-projection filtration (BPF) algorithm for cone-beam DPC-CT. Due to the differential nature of phase contrast projections, the algorithm restrains from differentiation of the projection data prior to back-projection, unlike BPF algorithms commonly used for absorption-based CT data. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a micro-focus x-ray tube source. Moreover, the numerical simulation and experimental results demonstrate that the proposed method can deal with several classes of truncated cone-beam datasets. We believe that this feature is of particular interest for future medical cone-beam phase-contrast CT imaging applications.

  18. Computer simulations of X-ray six-beam diffraction in a perfect silicon crystal. I.

    PubMed

    Kohn, V G; Khikhlukha, D R

    2016-05-01

    This paper reports computer simulations of the transmitted-beam intensity distribution for the case of six-beam (000, 220, 242, 044, -224, -202) diffraction of X-rays in a perfect silicon crystal of thickness 1 mm. Both the plane-wave angular dependence and the six-beam section topographs, which are usually obtained in experiments with a restricted beam (two-dimensional slit), are calculated. The angular dependence is calculated in accordance with Ewald's theory. The section topographs are calculated from the angular dependence by means of the fast Fourier transformation procedure. This approach allows one to consider, for the first time, the transformation of the topograph's structure due to the two-dimensional slit sizes and the distance between the slit and the detector. The results are in good agreement with the results of other works and with the experimental data. This method of calculation does not require a supercomputer and it was performed on a standard laptop. A detailed explanation of the main features of the diffraction patterns at different distances between the slit and the detector is presented.

  19. EVALUATION OF BALLISTIC DAMAGE IN AN ENCAPSULATED CERAMIC PANEL VIA X-RAY COMPUTED TOMOGRAPHY

    SciTech Connect

    Green, W. H.; Carter, R. H.

    2009-03-03

    X-ray computed tomography (XCT) is an important non-destructive evaluation technique for revealing the spatial distribution of ballistically-induced damage in ceramics. The level of detection and resolution of damage depends on the size of the sample and the parameters of the XCT approach (e.g., focal spot size, magnification, etc.). Previous and ongoing work in this area includes assessment of ballistically induced damage in both individual ceramic targets and ceramic armor panels. Ballistic damage in an encapsulated ceramic armor panel with a metal backing has been scanned and extensively evaluated using XCT 2-D and 3-D analysis. The purpose of using XCT evaluation in this study was to better characterize and understand all of the detectable damage. This information can be used to correlate damage features and types with the physical processes of damage initiation and growth. XCT scans and analyses of damage in the panel will be shown and discussed. This will include virtual 3-D solid visualizations and some quantitative analysis of damage features.

  20. X-Ray Computed Tomography Reveals the Response of Root System Architecture to Soil Texture.

    PubMed

    Rogers, Eric D; Monaenkova, Daria; Mijar, Medhavinee; Nori, Apoorva; Goldman, Daniel I; Benfey, Philip N

    2016-07-01

    Root system architecture (RSA) impacts plant fitness and crop yield by facilitating efficient nutrient and water uptake from the soil. A better understanding of the effects of soil on RSA could improve crop productivity by matching roots to their soil environment. We used x-ray computed tomography to perform a detailed three-dimensional quantification of changes in rice (Oryza sativa) RSA in response to the physical properties of a granular substrate. We characterized the RSA of eight rice cultivars in five different growth substrates and determined that RSA is the result of interactions between genotype and growth environment. We identified cultivar-specific changes in RSA in response to changing growth substrate texture. The cultivar Azucena exhibited low RSA plasticity in all growth substrates, whereas cultivar Bala root depth was a function of soil hardness. Our imaging techniques provide a framework to study RSA in different growth environments, the results of which can be used to improve root traits with agronomic potential. PMID:27208237

  1. Helical X-ray phase-contrast computed tomography without phase stepping

    PubMed Central

    Marschner, M.; Willner, M.; Potdevin, G.; Fehringer, A.; Noël, P. B.; Pfeiffer, F.; Herzen, J.

    2016-01-01

    X-ray phase-contrast computed tomography (PCCT) using grating interferometry provides enhanced soft-tissue contrast. The possibility to use standard polychromatic laboratory sources enables an implementation into a clinical setting. Thus, PCCT has gained significant attention in recent years. However, phase-contrast CT scans still require significantly increased measurement times in comparison to conventional attenuation-based CT imaging. This is mainly due to a time-consuming stepping of a grating, which is necessary for an accurate retrieval of the phase information. In this paper, we demonstrate a novel scan technique, which directly allows the determination of the phase signal without a phase-stepping procedure. The presented work is based on moiré fringe scanning, which allows fast data acquisition in radiographic applications such as mammography or in-line product analysis. Here, we demonstrate its extension to tomography enabling a continuous helical sample rotation as routinely performed in clinical CT systems. Compared to standard phase-stepping techniques, the proposed helical fringe-scanning procedure enables faster measurements, an extended field of view and relaxes the stability requirements of the system, since the gratings remain stationary. Finally, our approach exceeds previously introduced methods by not relying on spatial interpolation to acquire the phase-contrast signal. PMID:27052368

  2. Relationship of brain imaging with radionuclides and with x-ray computed tomography

    SciTech Connect

    Kuhl, D.E.

    1981-03-03

    Because of high sensitivity and specificity for altered local cerebral structure, x-ray computed tomography (CT) is the preferred initial diagnostic imaging study under most circumstances when cerebral disease is suspected. CT has no competitor for detecting fresh intracerebral hemorrhage. Radionuclide imaging (RN) scan is preferred when relative perfusion is to be assessed, in patients allergic to contrast media, and when an adequate CT study is not technically possible. (RN) plays an important complementary role to CT, especially for patients suspected of subacute or chronic subdura hematoma, cerebral infarction, arteriovenous malformations, meningitis, encephalitis, normal pressure hydrocephalus, or when CT findings are inconclusive. When CT is not available, RN serves as a good screening study for suspected cerebral tumor, infection, recent infarction, arteriovenous malformation, and chronic subdural hematoma. Future improvement in radionuclide imaging by means of emission composition potential. The compound plating approacl threshold for all the investigated transistors and fast neutron spectra lies within the raal. The value of the potential slightly changes with the coordinate change in this region, i.e. the charge on a collecting electrode is not practically guided up to a certain moment of time during the movement of nonequilibrium carriers.

  3. Quantitative assessment of myocardial perfusion using dynamic three-dimensional x-ray computed angiography

    SciTech Connect

    Teslow, T.N.

    1985-01-01

    Using computed tomogram time series, myocardial perfusion was angiographically measured as distributions of x-ray circulatory indicators in three dimensions. By separating the dynamic function from the cardiac structure, these separate components were tested using region-of-interest (ROI) mensuration in simulation, phantom, and in vivo experiments. Statistical criteria were used to evaluate the dynamic component which was represented by analytic mathematical models of indicator dilution. The spatial component was represented by three-dimensional (3-D) and two-dimensional (2-D) geometric models of the heart. Each of these components were determined in individual ROI's and globally integrated to manifest the perfusion heterogeneities. A physical heart phantom with controllable regional perfusion characteristics was also developed and studied. Experiments conducted on dogs compared the accuracy of 2-D and 3-D perfusion measurements by imaging to those using gamma-radioactive microspheres. Accurate reproducible localization of the heart was found to be important for obtaining accurate measures of regional perfusion in 3-D volume images exhibiting high noise.

  4. Towards geometrical calibration of x-ray computed tomography systems—a review

    NASA Astrophysics Data System (ADS)

    Ferrucci, Massimiliano; Leach, Richard K.; Giusca, Claudiu; Carmignato, Simone; Dewulf, Wim

    2015-09-01

    Industrial x-ray computed tomography (XCT) is seen as a potentially effective tool for the industrial inspection of complex parts. In particular, XCT is an attractive solution for the measurement of internal geometries, which are inaccessible by conventional coordinate measuring systems. While the technology is available and the benefits are recognized, methods to establish the measurement assurance of XCT systems are lacking. More specifically, the assessment of measurement uncertainty and the subsequent establishment of measurement traceability is a largely unknown process. This paper is a review of research that contributes to the development of a geometrical calibration procedure for XCT systems. A brief introduction to the geometry of cone-beam tomography systems is given, after which the geometrical influence factors are outlined. Mathematical measurement models play a significant role in understanding how geometrical offsets and misalignments contribute to error in measurements; therefore, the application of mathematical models in simulating geometrical errors is discussed and the corresponding literature is presented. Then, the various methods that have been developed to measure certain geometrical errors are reviewed. The findings from this review are discussed and suggestions are provided for future work towards the development of a comprehensive and practical geometrical calibration procedure.

  5. [Experiences with computer-assisted x-ray diagnosis of pulmonary coin lesions (author's transl)].

    PubMed

    Rotte, K H; Stier, M

    1976-08-01

    Favourable results of the computer-aided diagnosis of peripheral bronchial carcinoma lead to a simplified scheme for calculation fo diagnosis, basing upon X-ray symptoms. This scheme was tested in the Zentralinstitut für Krebsforschung (ZIK) in 102 pateints and in the Forschungsinstitut für Lungenkrankheiten und Tuberkulose (FLT) in 101 patients. These patients had coin lesions of the lung with unknown diagnoses. The histological diagnoses later proved were compared with the calculated diagnoses. In ZIK there were correct diagnosis in 92.16% (in 96.53% of the carcinomas, in 44.4% of the tuberculomas and in all benign tumors), while in FLT 85.53% of the coin lesions were correctly classified (89.13% of carcinomas, 79.31% of the tuberculomas and all benign tumors). The comparison with the clinical-histological diagnoses showed a clear improvement of the accuracy by the calculated diagnoses. The method can be recommended for the basic diagnosis especially of peripheral bronchial carcinoma. It implies a reduction of the diagnostic delay, but it can not substitute the histologic investigation of the lesions.

  6. Monitoring of stainless-steel slag carbonation using X-ray computed microtomography.

    PubMed

    Boone, Marijn A; Nielsen, Peter; De Kock, Tim; Boone, Matthieu N; Quaghebeur, Mieke; Cnudde, Veerle

    2014-01-01

    Steel production is one of the largest contributors to industrial CO2 emissions. This industry also generates large amounts of solid byproducts, such as slag and sludge. In this study, fine grained stainless-steel slag (SSS) is valorized to produce compacts with high compressive strength without the use of a hydraulic binder. This carbonation process is investigated on a pore-scale level to identify how the mineral phases in the SSS react with CO2, where carbonates are formed, and what the impact of these changes is on the pore network of the carbonated SSS compact. In addition to conventional research techniques, high-resolution X-ray computed tomography (HRXCT) is applied to visualize and quantify the changes in situ during the carbonation process. The results show that carbonates mainly precipitate at grain contacts and in capillary pores and this precipitation has little effect on the connectivity of the pore space. This paper also demonstrates the use of a custom-designed polymer reaction cell that allows in situ HRXCT analysis of the carbonation process. This shows the distribution and influence of water and CO2 in the pore network on the carbonate precipitation and, thus, the influence on the compressive strength development of the waste material.

  7. Validation of x-ray microfocus computed tomography as an imaging tool for porous structures

    SciTech Connect

    Kerckhofs, G.; Schrooten, J.; Lomov, S. V.; Wevers, M.; Cleynenbreugel, T. van

    2008-01-15

    X-ray microfocus computed tomography (micro-CT) is recently put forward to qualitatively and quantitatively characterize the internal structure of porous materials. However, it is known that artifacts such as the partial volume effect are inherently present in micro-CT images, thus resulting in a visualization error with respect to reality. This study proposes a validation protocol that in the future can be used to quantify this error for porous structures in general by matching micro-CT tomograms to microscopic sections. One of the innovations of the protocol is the opportunity to reconstruct an interpolated micro-CT image under the same angle as the physical cutting angle of the microscopic sections. Also, a novel thresholding method is developed based on matching micro-CT and microscopic images. In this study, titanium porous structures are assessed as proof of principle. It is concluded for these structures that micro-CT visualizes 89% of the total amount of voxels (solid and pore) correctly. However, 8% represents an overestimation of the real structure and 3% are real structural features not visualized by micro-CT. When exclusively focusing on the solid fraction in both the micro-CT and microscopic images, only an overestimation of about 5% is found.

  8. Helical X-ray phase-contrast computed tomography without phase stepping

    NASA Astrophysics Data System (ADS)

    Marschner, M.; Willner, M.; Potdevin, G.; Fehringer, A.; Noël, P. B.; Pfeiffer, F.; Herzen, J.

    2016-04-01

    X-ray phase-contrast computed tomography (PCCT) using grating interferometry provides enhanced soft-tissue contrast. The possibility to use standard polychromatic laboratory sources enables an implementation into a clinical setting. Thus, PCCT has gained significant attention in recent years. However, phase-contrast CT scans still require significantly increased measurement times in comparison to conventional attenuation-based CT imaging. This is mainly due to a time-consuming stepping of a grating, which is necessary for an accurate retrieval of the phase information. In this paper, we demonstrate a novel scan technique, which directly allows the determination of the phase signal without a phase-stepping procedure. The presented work is based on moiré fringe scanning, which allows fast data acquisition in radiographic applications such as mammography or in-line product analysis. Here, we demonstrate its extension to tomography enabling a continuous helical sample rotation as routinely performed in clinical CT systems. Compared to standard phase-stepping techniques, the proposed helical fringe-scanning procedure enables faster measurements, an extended field of view and relaxes the stability requirements of the system, since the gratings remain stationary. Finally, our approach exceeds previously introduced methods by not relying on spatial interpolation to acquire the phase-contrast signal.

  9. Computer simulation of the CSPAD, ePix10k, and RayonixMX170HS X-ray detectors

    SciTech Connect

    Tina, Adrienne

    2015-08-21

    The invention of free-electron lasers (FELs) has opened a door to an entirely new level of scientific research. The Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory is an X-ray FEL that houses several instruments, each with its own unique X-ray applications. This light source is revolutionary in that while its properties allow for a whole new range of scientific opportunities, it also poses numerous challenges. For example, the intensity of a focused X-ray beam is enough to damage a sample in one mere pulse; however, the pulse speed and extreme brightness of the source together are enough to obtain enough information about that sample, so that no further measurements are necessary. An important device in the radiation detection process, particularly for X-ray imaging, is the detector. The power of the LCLS X-rays has instigated a need for better performing detectors. The research conducted for this project consisted of the study of X-ray detectors to imitate their behaviors in a computer program. The analysis of the Rayonix MX170-HS, CSPAD, and ePix10k in particular helped to understand their properties. This program simulated the interaction of X-ray photons with these detectors to discern the patterns of their responses. A scientist’s selection process of a detector for a specific experiment is simplified from the characterization of the detectors in the program.

  10. Verification of high efficient broad beam cold cathode ion source

    NASA Astrophysics Data System (ADS)

    Abdel Reheem, A. M.; Ahmed, M. M.; Abdelhamid, M. M.; Ashour, A. H.

    2016-08-01

    An improved form of cold cathode ion source has been designed and constructed. It consists of stainless steel hollow cylinder anode and stainless steel cathode disc, which are separated by a Teflon flange. The electrical discharge and output characteristics have been measured at different pressures using argon, nitrogen, and oxygen gases. The ion exit aperture shape and optimum distance between ion collector plate and cathode disc are studied. The stable discharge current and maximum output ion beam current have been obtained using grid exit aperture. It was found that the optimum distance between ion collector plate and ion exit aperture is equal to 6.25 cm. The cold cathode ion source is used to deposit aluminum coating layer on AZ31 magnesium alloy using argon ion beam current which equals 600 μA. Scanning electron microscope and X-ray diffraction techniques used for characterizing samples before and after aluminum deposition.

  11. Verification of high efficient broad beam cold cathode ion source.

    PubMed

    Abdel Reheem, A M; Ahmed, M M; Abdelhamid, M M; Ashour, A H

    2016-08-01

    An improved form of cold cathode ion source has been designed and constructed. It consists of stainless steel hollow cylinder anode and stainless steel cathode disc, which are separated by a Teflon flange. The electrical discharge and output characteristics have been measured at different pressures using argon, nitrogen, and oxygen gases. The ion exit aperture shape and optimum distance between ion collector plate and cathode disc are studied. The stable discharge current and maximum output ion beam current have been obtained using grid exit aperture. It was found that the optimum distance between ion collector plate and ion exit aperture is equal to 6.25 cm. The cold cathode ion source is used to deposit aluminum coating layer on AZ31 magnesium alloy using argon ion beam current which equals 600 μA. Scanning electron microscope and X-ray diffraction techniques used for characterizing samples before and after aluminum deposition. PMID:27587108

  12. Air cathode structure manufacture

    DOEpatents

    Momyer, William R.; Littauer, Ernest L.

    1985-01-01

    An improved air cathode structure for use in primary batteries and the like. The cathode structure includes a matrix active layer, a current collector grid on one face of the matrix active layer, and a porous, nonelectrically conductive separator on the opposite face of the matrix active layer, the collector grid and separator being permanently bonded to the matrix active layer. The separator has a preselected porosity providing low IR losses and high resistance to air flow through the matrix active layer to maintain high bubble pressure during operation of the battery. In the illustrated embodiment, the separator was formed of porous polypropylene. A thin hydrophobic film is provided, in the preferred embodiment, on the current collecting metal grid.

  13. Probing the Dynamics of Biomineralization at the Pore Scale Using X-ray Computed Tomography

    NASA Astrophysics Data System (ADS)

    Armstrong, R. T.; Ajo Franklin, J. B.

    2009-12-01

    Biomineralization is a natural subsurface process that upon stimulation can dramatically affect soil mechanics and hydraulics. This work presents the results of a study where synchrotron based X-Ray Computed Microtomography (CMT) is used to investigate temporal cementation dynamics and the spatial distribution of biogenic CaCO3 at the pore-scale, thus, shedding light on pore clogging and contact cementation. To facilitate these studies we have developed a family of flow-through bioreactors (ID 8 mm) which can be scanned continuously during precipitation experiments. The reactor is also equipped with differential pressure transducers to allow measurement of sample permeability. Porosity permeability correlations, cementation morphology, CaCO3 spatial distribution, and bulk cementation are addressed herein. Sporosarcina pasteurii (formally Bacillus pasteurii), our model organism, is a prevalent aerobic, motile, soil microbe with a very active urease enzyme. Hydrolysis of urea by the urease enzyme generates carbonate ions, ammonium and an increase in pH which favors carbonate precipitation if appropriate metal cations (e.g. Ca2+) are available. Brightfield microscope results show that precipitation occurs within close proximity of the cell membrane reducing microbial motility and forming a CaCO3 precipitate with a "fluffy" appearance. Besides providing an aqueous environment favorable for mineralization S. pasteurii also provides nucleation sites on its cell membrane. Since this microbe is very effective at inducing carbonate precipitation over a relativity short time span (2-3 days), it was used exclusively in our experiments. Prior to CMT imaging the feasibility of temporal imaging was investigated. Viable cell counts taken before and after imaging showed that a considerable amount of bacteria survived the monochromatic (30 KeV) X-ray exposure. Cementation experiments initiated with inoculation of the CMT column with microbes and urea media, cells were allowed to

  14. Computer Assisted Instruction for Teaching Basic Money Handling Skills to Mentally Handicapped Students at Christine Meikle School in Calgary.

    ERIC Educational Resources Information Center

    Holz, Else; And Others

    The study involving 32 trainable mentally handicapped students (7 to 20 years old) investigated the effectiveness of computer assisted instruction (CAI) in teaching the necesary arithmetic skills for handling small amounts of money. Equipment used consisted of a Cathode Ray Tube (CRT) terminal interfaced with a random access slide projector, and a…

  15. Predicting the Number of Public Computer Terminals Needed for an On-Line Catalog: A Queuing Theory Approach.

    ERIC Educational Resources Information Center

    Knox, A. Whitney; Miller, Bruce A.

    1980-01-01

    Describes a method for estimating the number of cathode ray tube terminals needed for public use of an online library catalog. Authors claim method could also be used to estimate needed numbers of microform readers for a computer output microform (COM) catalog. Formulae are included. (Author/JD)

  16. Development of a portable x-ray computed tomographic imaging system for drill-site investigation of recovered core

    SciTech Connect

    Freifeld, Barry M.; Kneafsey, Timothy J.; Tomutsa, Liviu; Pruess, Jacob

    2003-05-01

    A portable x-ray computed tomography (CT) system was constructed for imaging core at drill sites. Performing drill-site-based x-ray scanning and CT analysis permits rapid evaluation of core properties (such as density, lithologic structure, and macroporosity distribution) and allows for real-time decision making for additional core-handling procedures. Because of the speed with which scanning is performed, systematic imaging and electronic cataloging of all retrieved core is feasible. Innovations (such as a novel clamshell shielding arrangement integrated with system interlocks) permit safe operation of the x-ray system in a busy core handling area. The minimization of the volume encapsulated with shielding reduces the overall system weight and facilitates instrument portability. The x-ray system as originally fabricated had a 110 kV x-ray source with a fixed 300-micron focal spot size. A 15 cm image intensifier with a cesium iodide phosphor input screen was coupled to a CCD for image capture. The CT system has since been modified with a 130 kV micro-focal x-ray source. With the x-ray system's variable focal spot size, high-resolution studies (10-micron resolution) can be performed on core plugs and coarser (100-micron resolution) images can be acquired of whole drill cores. The development of an aluminum compensator has significantly improved the dynamic range and accuracy of the system. An x-ray filter has also been incorporated, permitting rapid acquisition of multi-energy scans for more quantitative analysis of sample mineralogy. The x-ray CT system has operated reliably under extreme field conditions, which have varied from shipboard to arctic.

  17. Cathodochromic cathode ray tube: An operations manual

    NASA Technical Reports Server (NTRS)

    Heyman, P. M.

    1972-01-01

    A cathodochromic (CC) storage and display system capable of storing full TV resolution images has been built. The images are derived from standard TV signals: composite video, composite sync, composite blanking, horizontal drive, and vertical drive. Image storage takes place in the CC CRT; the fixed image is written for several TV frames for the contrast to be usable. Once stored on the CC CRT, the image can be read out in one of three modes: with the eye, a 35-mm camera, or a TV camera. Incoming information may also be stored in a storage tube similar to the CC CRT but with a phosphor layer behind the CC layer. By exciting the phosphor layer with a standard raster scan it is possible to read out an image stored in the CC layer in one of three modes: direct viewing, photography, or flying-spot readout using a photomultiplier.

  18. Thermionic emission cathodes

    SciTech Connect

    Misumi, A.; Saito, S.

    1981-07-21

    A thermionic emission cathode comprising a base metal made of nickel-tungsten series alloy, for example an alloy comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, and an emitter layer, which is formed on the base, made from a mixture of tungsten powder or nickel-tungsten alloy powder comprising 90 to 70% by weight of nickel and 10 to 30% by weight of tungsten, Ba/sub 3/Wo/sub 6/ powder and (C) zirconium powder or ZrH/sub 2/ powder, and if necessary interposing a powder layer between the base and the emitter layer, said powder layer having the same composition as the base metal and a particle size of 1 to 10 ..mu..m sealed on the surface of the base with a distribution density of 0.5 to 5.0 mg/cm/sup 2/, can be applied to both directly and indirectly heated type cathodes. Said cathode has such advantages as being able to be miniaturized and to have high current density.

  19. Consequences of using nonlinear particle trajectories to compute spatial diffusion coefficients. [for cosmic ray propagation in interstellar and interplanetary space

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.

    1977-01-01

    In a study of cosmic ray propagation in interstellar and interplanetary space, a perturbed orbit resonant scattering theory for pitch angle diffusion in a slab model of magnetostatic turbulence is slightly generalized and used to compute the diffusion coefficient for spatial propagation parallel to the mean magnetic field. This diffusion coefficient has been useful for describing the solar modulation of the galactic cosmic rays, and for explaining the diffusive phase in solar flares in which the initial anisotropy of the particle distribution decays to isotropy.

  20. DETERMINATION OF HLW GLASS MELT RATE USING X-RAY COMPUTED TOMOGRAPHY

    SciTech Connect

    Choi, A.; Miller, D.; Immel, D.

    2011-10-06

    significant amount of glassy material interspersed among the gas bubbles will be excluded, thus underestimating the melt rate. Likewise, if they are drawn too high, many large voids will be counted as glass, thus overestimating the melt rate. As will be shown later in this report, there is also no guarantee that a given distribution of glass and gas bubbles along a particular sectioned plane will always be representative of the entire sample volume. Poor reproducibility seen in some LMR data may be related to these difficulties of the visual method. In addition, further improvement of the existing melt rate model requires that the overall impact of feed chemistry on melt rate be reflected on measured data at a greater quantitative resolution on a more consistent basis than the visual method can provide. An alternate method being pursued is X-ray computed tomography (CT). It involves X-ray scanning of glass samples, performing CT on the 2-D X-ray images to build 3-D volumetric data, and adaptive segmentation analysis of CT results to not only identify but quantify the distinct regions within each sample based on material density and morphologies. The main advantage of this new method is that it can determine the relative local density of the material remaining in the beaker after the heat treatment regardless of its morphological conditions by selectively excluding all the voids greater than a given volumetric pixel (voxel) size, thus eliminating much of the subjectivity involved in the visual method. As a result, the melt rate data obtained from CT scan will give quantitative descriptions not only on the fully-melted glass, but partially-melted and unmelted feed materials. Therefore, the CT data are presumed to be more reflective of the actual melt rate trends in continuously-fed melters than the visual data. In order to test the applicability of X-ray CT scan to the HLW glass melt rate study, several new series of HLW simulant/frit mixtures were melted in the Melt Rate

  1. Interactive graphics system for IBM 1800 computer

    NASA Technical Reports Server (NTRS)

    Carleton, T. P.; Howell, D. R.; Mish, W. H.

    1972-01-01

    A FORTRAN compatible software system that has been developed to provide an interactive graphics capability for the IBM 1800 computer is described. The interactive graphics hardware consists of a Hewlett-Packard 1300A cathode ray tube, Sanders photopen, digital to analog converters, pulse counter, and necessary interface. The hardware is available from IBM as several related RPQ's. The software developed permits the application programmer to use IBM 1800 FORTRAN to develop a display on the cathode ray tube which consists of one or more independent units called pictures. The software permits a great deal of flexibility in the manipulation of these pictures and allows the programmer to use the photopen to interact with the displayed data and make decisions based on information returned by the photopen.

  2. Reciprocal Grids: A Hierarchical Algorithm for Computing Solution X-ray Scattering Curves from Supramolecular Complexes at High Resolution.

    PubMed

    Ginsburg, Avi; Ben-Nun, Tal; Asor, Roi; Shemesh, Asaf; Ringel, Israel; Raviv, Uri

    2016-08-22

    In many biochemical processes large biomolecular assemblies play important roles. X-ray scattering is a label-free bulk method that can probe the structure of large self-assembled complexes in solution. As we demonstrate in this paper, solution X-ray scattering can measure complex supramolecular assemblies at high sensitivity and resolution. At high resolution, however, data analysis of larger complexes is computationally demanding. We present an efficient method to compute the scattering curves from complex structures over a wide range of scattering angles. In our computational method, structures are defined as hierarchical trees in which repeating subunits are docked into their assembly symmetries, describing the manner subunits repeat in the structure (in other words, the locations and orientations of the repeating subunits). The amplitude of the assembly is calculated by computing the amplitudes of the basic subunits on 3D reciprocal-space grids, moving up in the hierarchy, calculating the grids of larger structures, and repeating this process for all the leaves and nodes of the tree. For very large structures, we developed a hybrid method that sums grids of smaller subunits in order to avoid numerical artifacts. We developed protocols for obtaining high-resolution solution X-ray scattering data from taxol-free microtubules at a wide range of scattering angles. We then validated our method by adequately modeling these high-resolution data. The higher speed and accuracy of our method, over existing methods, is demonstrated for smaller structures: short microtubule and tobacco mosaic virus. Our algorithm may be integrated into various structure prediction computational tools, simulations, and theoretical models, and provide means for testing their predicted structural model, by calculating the expected X-ray scattering curve and comparing with experimental data. PMID:27410762

  3. Fast estimation of first-order scattering in a medical x-ray computed tomography scanner using a ray-tracing technique.

    PubMed

    Liu, Xin

    2014-01-01

    This study describes a deterministic method for simulating the first-order scattering in a medical computed tomography scanner. The method was developed based on a physics model of x-ray photon interactions with matter and a ray tracing technique. The results from simulated scattering were compared to the ones from an actual scattering measurement. Two phantoms with homogeneous and heterogeneous material distributions were used in the scattering simulation and measurement. It was found that the simulated scatter profile was in agreement with the measurement result, with an average difference of 25% or less. Finally, tomographic images with artifacts caused by scatter were corrected based on the simulated scatter profiles. The image quality improved significantly.

  4. Noise properties of grating-based x-ray phase contrast computed tomography

    SciTech Connect

    Koehler, Thomas; Juergen Engel, Klaus; Roessl, Ewald

    2011-05-15

    Purpose: To investigate the properties of tomographic grating-based phase contrast imaging with respect to its noise power spectrum and the energy dependence of the achievable contrast to noise ratio. Methods: Tomographic simulations of an object with 11 cm diameter constituted of materials of biological interest were conducted at different energies ranging from 25 to 85 keV by using a wave propagation approach. Using a Monte Carlo simulation of the x-ray attenuation within the object, it is verified that the simulated measurement deposits the same dose within the object at each energy. Results: The noise in reconstructed phase contrast computed tomography images shows a maximum at low spatial frequencies. The contrast to noise ratio reaches a maximum around 45 keV for the simulated object. The general dependence of the contrast to noise on the energy appears to be independent of the material. Compared with reconstructed absorption contrast images, the reconstructed phase contrast images show sometimes better, sometimes worse, and sometimes similar contrast to noise, depending on the material and the energy. Conclusions: Phase contrast images provide additional information to the conventional absorption contrast images and might thus be useful for medical applications. However, the observed noise power spectrum in reconstructed phase contrast images implies that the usual trade-off between noise and resolution is less efficient for phase contrast imaging compared with absorption contrast imaging. Therefore, high-resolution imaging is a strength of phase contrast imaging, but low-resolution imaging is not. This might hamper the clinical application of the method, in cases where a low spatial resolution is sufficient for diagnosis.

  5. High-resolution X-ray computed tomography scanning of primate copulatory plugs.

    PubMed

    Parga, Joyce A; Maga, Murat; Overdorff, Deborah J

    2006-04-01

    In this study, high-resolution computed tomography X-ray scanning was used to scan ring-tailed lemur (Lemur catta) copulatory plugs. This method produced accurate measures of plug volume and surface area, but was not useful for visualizing plug internal structure. Copulatory plug size was of interest because it may relate to male fertilization success. Copulatory plugs form from coagulated ejaculate, and are routinely displaced in this species by the penis of a subsequent mate during copulation (Parga [2003] Int. J. Primatol. 24:889-899). Because one potential function of these plugs may be to preclude or delay other males' successful insemination of females, we tested the hypothesis that larger plugs are more difficult for subsequent males to displace. Plugs were collected opportunistically upon displacement during data collection on L. catta mating behavior on St. Catherines Island, Georgia (USA) during two subsequent breeding seasons. Copulatory plugs exhibited a wide range of volumes: 1,758-5,013.6 mm3 (n = 9). Intraindividual differences in plug volume were sometimes greater than interindividual differences. Contrary to predictions, larger plugs were not more time-consuming for males to displace via penile intromission during copulation. Nor were plugs with longer vaginal residence times notably smaller than plugs with shorter residence times, as might be expected if plugs disintegrate while releasing sperm (Asdell [1946] Patterns of Mammalian Reproduction; Ithaca: Comstock). We found a significant inverse correlation between number of copulatory mounts leading to ejaculation and copulatory plug volume. This may indicate that if males are sufficiently sexually aroused to reach ejaculation in fewer mounts, they tend to produce ejaculates of greater volume. PMID:16345065

  6. Microstructural Characterization of Fried Potato Disks Using X-Ray Micro Computed Tomography.

    PubMed

    Alam, Tanjila; Takhar, Pawan S

    2016-03-01

    Microstructural properties play a key role to affect oil uptake and product quality during frying of foods. The objective of this study was to observe the complex microstructural changes and mass transfer mechanisms in potato disks during frying. The potato disks of 1.65 mm thickness were fried at 190 °C for 0, 20, 40, 60, and 80 s. X-ray micro-computed tomography (CT) was used for 3-dimensional (3D) imaging of microstructure of porous potato disks. Total porosity, pore size distribution, oil content, and air content of potato disks were calculated from resulting 3D data sets. Oil and air content measured by analysis of micro-CT images followed trends similar to Soxtec and gas pycnometry methods, respectively. Image analysis showed a significant change in pore size distribution as a function of frying time. Frying time was also observed to have an effect on tortuosity, which is an important microstructural fluid transport property. Tortuosity was measured by path length ratio method from 3D data sets obtained from image analysis. A linear inverse relationship was observed between porosity and tortuosity where tortuosity decreased with the increase of porosity. It was also observed that during frying, oil content increased with the decrease of tortuosity. This phenomenon indicated that the lower tortuosity created a less complicated and sinuous path, thus resulting in less resistance to oil penetration. Micro-CT technique can serve as an effective tool for elucidating microstructure of fried foods, and can provide complementary information to conventional lab techniques.

  7. Developing advanced X-ray scattering methods combined with crystallography and computation.

    PubMed

    Perry, J Jefferson P; Tainer, John A

    2013-03-01

    The extensive use of small angle X-ray scattering (SAXS) over the last few years is rapidly providing new insights into protein interactions, complex formation and conformational states in solution. This SAXS methodology allows for detailed biophysical quantification of samples of interest. Initial analyses provide a judgment of sample quality, revealing the potential presence of aggregation, the overall extent of folding or disorder, the radius of gyration, maximum particle dimensions and oligomerization state. Structural characterizations include ab initio approaches from SAXS data alone, and when combined with previously determined crystal/NMR, atomistic modeling can further enhance structural solutions and assess validity. This combination can provide definitions of architectures, spatial organizations of protein domains within a complex, including those not determined by crystallography or NMR, as well as defining key conformational states of a protein interaction. SAXS is not generally constrained by macromolecule size, and the rapid collection of data in a 96-well plate format provides methods to screen sample conditions. This includes screening for co-factors, substrates, differing protein or nucleotide partners or small molecule inhibitors, to more fully characterize the variations within assembly states and key conformational changes. Such analyses may be useful for screening constructs and conditions to determine those most likely to promote crystal growth of a complex under study. Moreover, these high throughput structural determinations can be leveraged to define how polymorphisms affect assembly formations and activities. This is in addition to potentially providing architectural characterizations of complexes and interactions for systems biology-based research, and distinctions in assemblies and interactions in comparative genomics. Thus, SAXS combined with crystallography/NMR and computation provides a unique set of tools that should be considered

  8. Computation of Radiation Dose at Aircraft Altitudes from Analysis of Cosmic Ray Neutron Monitor Data

    NASA Astrophysics Data System (ADS)

    Smart, D. F.; Shea, M. A.

    Relativistic solar proton events GLEs those events with protons having sufficient kinetic energy to initiate a nuclear cascade in the atmosphere can make a contribution to radiation dose at aircraft altitudes We show that it is possible to obtain proper estimates of the expected radiation dose at aircraft altitudes from the analysis of ground-level neutron monitor data Assuming a nominal GLE spectrum the radiation dose at 40 000 feet during a 100 increase at polar latitudes will be in the range of 5 to 10 micro Sieverts per hour depending on the spectral slope An analysis of the large GLE s that have occurred during the past two solar cycles shows that there have been no events where the hourly averaged radiation dose at 40 000 feet would have exceeded 20 micro Sieverts per hour In the past improper GLE analysis was used to estimate the radiation dose at aircraft altitudes The old values derived for the early GLE s resulted in the prediction of high dose rates that persist today as urban legends and contribute to the public concept that the radiation dose at aircraft altitudes is dangerous We demonstrate that modern analytical techniques result in computed radiation doses during high-energy solar cosmic ray events that are orders of magnitude lower than those obtained by the old techniques We show that the use of the old technique of using straight line power law spectra to extrapolate the flux derived at 1 GeV results in order of magnitude errors when these flux values are extrapolated to lower energies and used to

  9. Developing advanced x-ray scattering methods combined with crystallography and computation

    PubMed Central

    Perry, J. Jefferson P.; Tainer, John A.

    2013-01-01

    The extensive use of small angle x-ray scattering (SAXS) over the last few years is rapidly providing new insights into protein interactions, complex formation and conformational states in solution. This SAXS methodology allows for detailed biophysical quantification of samples of interest. Initial analyses provide a judgment of sample quality, revealing the potential presence of aggregation, the overall extent of folding or disorder, the radius of gyration, maximum particle dimensions and oligomerization state. Structural characterizations include ab initio approaches from SAXS data alone, and when combined with previously determined crystal/NMR, atomistic modeling can further enhance structural solutions and assess validity. This combination can provide definitions of architectures, spatial organizations of protein domains within a complex, including those not determined by crystallography or NMR, as well as defining key conformational states of a protein interaction. SAXS is not generally constrained by macromolecule size, and the rapid collection of data in a 96-well plate format provides methods to screen sample conditions. This includes screening for co-factors, substrates, differing protein or nucleotide partners or small molecule inhibitors, to more fully characterize the variations within assembly states and key conformational changes. Such analyses may be useful for screening constructs and conditions to determine those most likely to promote crystal growth of a complex under study. Moreover, these high throughput structural determinations can be leveraged to define how polymorphisms affect assembly formations and activities. This is in addition to potentially providing architectural characterizations of complexes and interactions for systems biology-based research, and distinctions in assemblies and interactions in comparative genomics. Thus, SAXS combined with crystallography/NMR and computation provides a unique set of tools that should be considered

  10. Computation of rms spot radii by ray tracing. [size determination through telescope

    NASA Technical Reports Server (NTRS)

    Foreman, J. W., Jr.

    1974-01-01

    In a ray trace calculation of the rms radius of the spot formed in the image plane of an optical system by a point source object, a decision must be made as to how many rays will be traced to obtain the result. As the number of rays is increased, the rms spot radius is generally found to decrease, apparently approaching a definite lower limit as the number of rays becomes very large. This paper examines the question of how many rays must be traced and what their geometrical distribution within the aperture should be to approach the limiting value of the rms spot radius for an infinite number of rays within an accuracy of approximately 1%.

  11. Using Multispectral Imaging to Measure Temperature Profiles and Emissivity of Large Thermionic Dispenser, Cathodes

    SciTech Connect

    D.F. Simmons; C.M. Fortgang; D.B. Holtkamp

    2001-09-01

    Thermionic dispenser cathodes are widely used in modern high-power microwave tubes. Use of these cathodes has led to significant improvement in performance. In recent years these cathodes have been used in electron linear accelerators (LINACs), particularly in induction LINACs, such as the Experimental Test Accelerator at Lawrence Livermore National Laboratory and the Relativistic Test Accelerator at Lawrence Berkeley National Laboratory. For induction LINACs, the thermionic dispenser cathode provides greater reproducibility, longer pulse lengths, and lower emittance beams than does a field emission cathode. Los Alamos National Laboratory is fabricating a dual-axis X-ray radiography machine called dual-axis radiograph hydrodynamic test (DARHT). The second axis of DARHT consists of a 2-kA, 20-MeV induction LINAC that uses a 3.2-MeV electron gun with a tungsten thermionic-dispenser cathode. Typically the DARHT cathode current density is 10 A/cm{sup 2} at 1050 C. Under these conditions current density is space-charge limited, which is desirable since current density is independent of temperature. At lower temperature (the temperature-limited regime) there are variations in the local current density due to a nonuniform temperature profile. To obtain the desired uniform current density associated with space-charge limited operation, the coolest area on the cathode must be at a sufficiently high temperature so that the emission is space-charge limited. Consequently, the rest of the cathode is emitting at the same space-charge-limited current density but is at a higher temperature than necessary. Because cathode lifetime is such a strong function of cathode temperature, there is a severe penalty for nonuniformity in the cathode temperature. For example, a temperature increase of 50 C means cathode lifetime will decrease by a factor of at least four. Therefore, we are motivated to measure the temperature profiles of our large-area cathodes.

  12. Long cycle life lithium ion battery with lithium nickel cobalt manganese oxide (NCM) cathode

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Xiong, L.; He, C.

    2014-09-01

    Lithium ion batteries with lithium nickel cobalt manganese oxide (NCM) cathode were characterized by extensive cycling (>2000 cycles), discharge rate test, hybrid pulse power characterization test (HPPC), and electrochemical impedance spectroscopy (EIS). The crystal structure, morphology and particle size of cathode materials were characterized by X-ray diffraction and scanning electron microscopy (SEM). It was demonstrated that the rate performance and cycle life of battery are closely related to the cathode material composition and electrode design. With proper selection of cathode composition and electrode design, the lithium ion battery cell achieved close to 3500 cycles with 85% capacity retention at 1C current.

  13. Light extraction efficiency of a top-emission organic light-emitting diode with an Yb/Au double-layer cathode and an opaque Si anode.

    PubMed

    Ran, G Z; Ma, G L; Xu, Y H; Dai, L; Qin, G G

    2006-08-10

    We have computed the transmittances of four types of cathode--Yb/Au, Al/Au, Yb/Ag, and Al/Ag double layers--and the light extraction efficiencies of the top-emission organic light-emitting diodes with these cathodes, respectively, based on the characteristic matrix method and the dissipation spectrum model. Computations show that the Yb/Au cathode has a markedly higher transmittance than the other three types of cathode when the Yb and Au thicknesses in the Yb/Au cathode are, respectively, equal to the Al (or Yb) and Au (or Ag) thicknesses in the other three types of cathode. The power lost to the Yb/Au cathode due to the surface plasmon polaritons is the lowest, and hence the device with the Yb/Au cathode has the highest extraction efficiency. The transmittances for the four cathodes are also measured experimentally.

  14. Light extraction efficiency of a top-emission organic light-emitting diode with an Yb/Au double-layer cathode and an opaque Si anode

    NASA Astrophysics Data System (ADS)

    Ran, G. Z.; Ma, G. L.; Xu, Y. H.; Dai, L.; Qin, G. G.

    2006-08-01

    We have computed the transmittances of four types of cathode--Yb/Au, Al/Au, Yb/Ag, and Al/Ag double layers--and the light extraction efficiencies of the top-emission organic light-emitting diodes with these cathodes, respectively, based on the characteristic matrix method and the dissipation spectrum model. Computations show that the Yb/Au cathode has a markedly higher transmittance than the other three types of cathode when the Yb and Au thicknesses in the Yb/Au cathode are, respectively, equal to the Al (or Yb) and Au (or Ag) thicknesses in the other three types of cathode. The power lost to the Yb/Au cathode due to the surface plasmon polaritons is the lowest, and hence the device with the Yb/Au cathode has the highest extraction efficiency. The transmittances for the four cathodes are also measured experimentally.

  15. Cybersecurity, massive data processing, community interaction, and other developments at WWW-based computational X-ray Server

    NASA Astrophysics Data System (ADS)

    Stepanov, Sergey

    2013-03-01

    X-Ray Server (x-server.gmca.aps.anl.gov) is a WWW-based computational server for modeling of X-ray diffraction, reflection and scattering data. The modeling software operates directly on the server and can be accessed remotely either from web browsers or from user software. In the later case the server can be deployed as a software library or a data fitting engine. As the server recently surpassed the milestones of 15 years online and 1.5 million calculations, it accumulated a number of technical solutions that are discussed in this paper. The developed approaches to detecting physical model limits and user calculations failures, solutions to spam and firewall problems, ways to involve the community in replenishing databases and methods to teach users automated access to the server programs may be helpful for X-ray researchers interested in using the server or sharing their own software online.

  16. Poly-ε-caprolactone tungsten oxide nanoparticles as a contrast agent for X-ray computed tomography.

    PubMed

    Jakhmola, Anshuman; Anton, Nicolas; Anton, Halina; Messaddeq, Nadia; Hallouard, François; Klymchenko, Andrey; Mely, Yves; Vandamme, Thierry F

    2014-03-01

    Inorganic nanomaterials based on heavy elements represent a new class of contrast agents for X-ray computed tomography (CT). Recent advances have shown that these materials are highly suited for CT imaging due to their high density and X-ray absorption capabilities. In this contribution, we demonstrated that tungsten oxide (WO3) nanoparticles coated by poly-ε-caprolactone (PCL) can be used as efficient contrast agent for CT imaging. The obtained particles were characterized by electron microscopy (TEM and SEM), and dynamic light scattering (DLS). We also validated their use for enhanced in vivo imaging, since these nanoparticles were observed to display high X-ray attenuation properties and circulation time (up to 3 h), permitting blood pool imaging.

  17. Evaluation of pore structures and cracking in cement paste exposed to elevated temperatures by X-ray computed tomography

    SciTech Connect

    Kim, Kwang Yeom; Yun, Tae Sup; Park, Kwang Pil

    2013-08-15

    When cement-based materials are exposed to the high temperatures induced by fire, which can rapidly cause temperatures of over 1000 °C, the changes in pore structure and density prevail. In the present study, mortar specimens were subjected to a series of increasing temperatures to explore the temperature-dependent evolution of internal pore structure. High-performance X-ray computed tomography (CT) was used to observe the evolution of temperature-induced discontinuities at the sub-millimeter level. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to investigate the cause of physical changes in the heated mortar specimens. Results exhibit the changes in pore structure caused by elevated temperatures, and thermally induced fractures. We discuss the progressive formation of thermally induced fracture networks, which is a prerequisite for spalling failure of cement-based materials by fire, based on visual observations of the 3D internal structures revealed by X-ray CT.

  18. A Comparison of the Effects of Information Mapped Learning Materials and Traditional Materials on the Learning of Concepts via the Printed Page and Computer Cathode Ray Tube.

    ERIC Educational Resources Information Center

    Geisert, Paul

    A study was made of the learning effects of information mapping; i.e., the technique of organizing materials on the printed page in a format which clearly illustrates the order and organization of the materials. The investigation of the effects of information mapping and information-mapped feedback on achievement, time variables, and attitude…

  19. Feasibility studies on explosive detection and homeland security applications using a neutron and x-ray combined computed tomography system

    NASA Astrophysics Data System (ADS)

    Sinha, V.; Srivastava, A.; Lee, H. K.; Liu, X.

    2013-05-01

    The successful creation and operation of a neutron and X-ray combined computed tomography (NXCT) system has been demonstrated by researchers at the Missouri University of Science and Technology. The NXCT system has numerous applications in the field of material characterization and object identification in materials with a mixture of atomic numbers represented. Presently, the feasibility studies have been performed for explosive detection and homeland security applications, particularly in concealed material detection and determination of the light atomic number materials. These materials cannot be detected using traditional X-ray imaging. The new system has the capability to provide complete structural and compositional information due to the complementary nature of X-ray and neutron interactions with materials. The design of the NXCT system facilitates simultaneous and instantaneous imaging operation, promising enhanced detection capabilities of explosive materials, low atomic number materials and illicit materials for homeland security applications. In addition, a sample positioning system allowing the user to remotely and automatically manipulate the sample makes the system viable for commercial applications. Several explosives and weapon simulants have been imaged and the results are provided. The fusion algorithms which combine the data from the neutron and X-ray imaging produce superior images. This paper is a compete overview of the NXCT system for feasibility studies of explosive detection and homeland security applications. The design of the system, operation, algorithm development, and detection schemes are provided. This is the first combined neutron and X-ray computed tomography system in operation. Furthermore, the method of fusing neutron and X-ray images together is a new approach which provides high contrast images of the desired object. The system could serve as a standardized tool in nondestructive testing of many applications, especially in

  20. Hybrid deterministic and stochastic x-ray transport simulation for transmission computed tomography with advanced detector noise model

    NASA Astrophysics Data System (ADS)

    Popescu, Lucretiu M.

    2016-03-01

    We present a model for simulation of noisy X-ray computed tomography data sets. The model is made of two main components, a photon transport simulation component that generates the noiseless photon field incident on the detector, and a detector response model that takes as input the incident photon field parameters and given the X-ray source intensity and exposure time can generate noisy data sets, accordingly. The photon transport simulation component combines direct ray-tracing of polychromatic X-rays for calculation of transmitted data, with Monte Carlo simulation for calculation of the scattered-photon data. The Monte Carlo scatter simulation is accelerated by implementing particle splitting and importance sampling variance reduction techniques. The detector-incident photon field data are stored as energy expansion coefficients on a refined grid that covers the detector area. From these data the detector response model is able to generate noisy detector data realizations, by reconstituting the main parameters that describe each detector element response in statistical terms, including spatial correlations. The model is able to generate very fast, on the fly, CT data sets corresponding to different radiation doses, as well as detector response characteristics, facilitating data management in extensive optimization studies by reducing the computation time and storage space demands.

  1. High-speed photon-counting x-ray computed tomography system utilizing a multipixel photon counter

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Enomoto, Toshiyuki; Watanabe, Manabu; Hitomi, Keitaro; Takahashi, Kiyomi; Sato, Shigehiro; Ogawa, Akiro; Onagawa, Jun

    2009-07-01

    High-speed photon counting is useful for discriminating photon energy and for decreasing absorbed dose for patients in medical radiography, and the counting is usable for constructing an x-ray computed tomography (CT) system. A photon-counting x-ray CT system is of the first generation type and consists of an x-ray generator, a turn table, a translation stage, a two-stage controller, a multipixel photon counter (MPPC) module, a 1.0-mm-thick LSO crystal (scintillator), a counter card (CC), and a personal computer (PC). Tomography is accomplished by repeating the linear scanning and the rotation of an object, and projection curves of the object are obtained by the linear scanning using the detector consisting of a MPPC module and the LSO. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. The lower level of the photon energy is roughly determined by a comparator circuit in the module, and the unit of the level is the photon equivalent (pe). Thus, the average photon energy of the x-ray spectra increases with increasing the lower-level voltage of the comparator. The maximum count rate was approximately 20 Mcps, and energy-discriminated CT was roughly carried out.

  2. A reference sample for investigating the stability of the imaging system of x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Sun, Wenjuan; Brown, Stephen; Flay, Nadia; McCarthy, Michael; McBride, John

    2016-08-01

    The use of x-ray computed tomography for dimensional measurements associated with engineering applications has flourished in recent years. However, error sources associated with the technology are not well understood. In this paper, a novel two-sphere reference sample has been developed and used to investigate the stability of the imaging system that consists of an x-ray tube and a detector. In contrast with other research work reported, this work considered relative positional variation along the x-, y- and z-axes. This sample is a significant improvement over the one sphere sample proposed previously, which can only be used to observe the stability of the imaging system along x- and y-axes. Temperature variations of different parts of the system have been monitored and the relationship between temperature variations and x-ray image stability has been studied. Other effects that may also influence the stability of the imaging system have been discussed. The proposed reference sample and testing method are transferable to other types of x-ray computed tomography systems, for example, systems with transmission targets and systems with sub-micrometre focal spots.

  3. A Computer Program for Calculation of Calibration Curves for Quantitative X-Ray Diffraction Analysis.

    ERIC Educational Resources Information Center

    Blanchard, Frank N.

    1980-01-01

    Describes a FORTRAN IV program written to supplement a laboratory exercise dealing with quantitative x-ray diffraction analysis of mixtures of polycrystalline phases in an introductory course in x-ray diffraction. Gives an example of the use of the program and compares calculated and observed calibration data. (Author/GS)

  4. Effect of Cathode Designs on Radiation Emission of Compact Diode (CD) Device

    NASA Astrophysics Data System (ADS)

    Khan, Muhammad Zubair; Yap, Seong Ling; Khan, Muhammad Afzal; Attiq-ur-Rehman; Zakaullah, Muhammad

    2013-02-01

    A comparative study on the radiation emission such as X-ray yield and efficiency has been carried out in compact diode device. Two different designs of cathode having sharp-edged razor blade (of 0.5 mm thickness with width 2 mm) and a sewing machine needle (of 0.5 mm diameter at tip with length of 39 mm) have been tested for this study. The radiation emission (X-ray yield) was determined by employing two set of PIN diodes at fixed positions. The maximum X-ray yield depends on cathode designs and electrodes separation in few mm. The yield of X-ray is small in the case of sharp-edged razor blade cathode than the sewing machine needle cathode. The X-ray yield, measured by 4π-geometry, shows its dependence on the cathode designs. The maximum X-ray yield is found to be 939.2 ± 65.7 mJ with efficiency of 0.4142 ± 0.0289%. This study indicates that the compact diode device could be optimized to a great extent for optimal X-ray yield by using an appropriate cathode design.

  5. Computer-Aided Remote Driving

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian H.

    1994-01-01

    System for remote control of robotic land vehicle requires only small radio-communication bandwidth. Twin video cameras on vehicle create stereoscopic images. Operator views cross-polarized images on two cathode-ray tubes through correspondingly polarized spectacles. By use of cursor on frozen image, remote operator designates path. Vehicle proceeds to follow path, by use of limited degree of autonomous control to cope with unexpected conditions. System concept, called "computer-aided remote driving" (CARD), potentially useful in exploration of other planets, military surveillance, firefighting, and clean-up of hazardous materials.

  6. Titanium diaphragm makes excellent amplitron cathode support

    NASA Technical Reports Server (NTRS)

    Teich, W. W.

    1965-01-01

    Cathode support structure designed around a titanium diaphragm prevents radial misalignment between the cathode and anode in amplitrons. The titanium exhibits low thermal conductivity, tolerates lateral thermal expansion of the cathode, and is a poor primary and secondary emission medium.

  7. Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography

    PubMed Central

    Walton, Lucy A.; Bradley, Robert S.; Withers, Philip J.; Newton, Victoria L.; Watson, Rachel E. B.; Austin, Clare; Sherratt, Michael J.

    2015-01-01

    Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons. PMID:25975937

  8. Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography.

    PubMed

    Walton, Lucy A; Bradley, Robert S; Withers, Philip J; Newton, Victoria L; Watson, Rachel E B; Austin, Clare; Sherratt, Michael J

    2015-05-15

    Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons.

  9. Quantitative imaging of gold nanoparticle distribution in a tumor-bearing mouse using benchtop x-ray fluorescence computed tomography

    PubMed Central

    Manohar, Nivedh; Reynoso, Francisco J.; Diagaradjane, Parmeswaran; Krishnan, Sunil; Cho, Sang Hyun

    2016-01-01

    X-ray fluorescence computed tomography (XFCT) is a technique that can identify, quantify, and locate elements within objects by detecting x-ray fluorescence (characteristic x-rays) stimulated by an excitation source, typically derived from a synchrotron. However, the use of a synchrotron limits practicality and accessibility of XFCT for routine biomedical imaging applications. Therefore, we have developed the ability to perform XFCT on a benchtop setting with ordinary polychromatic x-ray sources. Here, we report our postmortem study that demonstrates the use of benchtop XFCT to accurately image the distribution of gold nanoparticles (GNPs) injected into a tumor-bearing mouse. The distribution of GNPs as determined by benchtop XFCT was validated using inductively coupled plasma mass spectrometry. This investigation shows drastically enhanced sensitivity and specificity of GNP detection and quantification with benchtop XFCT, up to two orders of magnitude better than conventional x-ray CT. The results also reaffirm the unique capabilities of benchtop XFCT for simultaneous determination of the spatial distribution and concentration of nonradioactive metallic probes, such as GNPs, within the context of small animal imaging. Overall, this investigation identifies a clear path toward in vivo molecular imaging using benchtop XFCT techniques in conjunction with GNPs and other metallic probes. PMID:26912068

  10. Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography.

    PubMed

    Walton, Lucy A; Bradley, Robert S; Withers, Philip J; Newton, Victoria L; Watson, Rachel E B; Austin, Clare; Sherratt, Michael J

    2015-01-01

    Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons. PMID:25975937

  11. Quantitative imaging of gold nanoparticle distribution in a tumor-bearing mouse using benchtop x-ray fluorescence computed tomography

    NASA Astrophysics Data System (ADS)

    Manohar, Nivedh; Reynoso, Francisco J.; Diagaradjane, Parmeswaran; Krishnan, Sunil; Cho, Sang Hyun

    2016-02-01

    X-ray fluorescence computed tomography (XFCT) is a technique that can identify, quantify, and locate elements within objects by detecting x-ray fluorescence (characteristic x-rays) stimulated by an excitation source, typically derived from a synchrotron. However, the use of a synchrotron limits practicality and accessibility of XFCT for routine biomedical imaging applications. Therefore, we have developed the ability to perform XFCT on a benchtop setting with ordinary polychromatic x-ray sources. Here, we report our postmortem study that demonstrates the use of benchtop XFCT to accurately image the distribution of gold nanoparticles (GNPs) injected into a tumor-bearing mouse. The distribution of GNPs as determined by benchtop XFCT was validated using inductively coupled plasma mass spectrometry. This investigation shows drastically enhanced sensitivity and specificity of GNP detection and quantification with benchtop XFCT, up to two orders of magnitude better than conventional x-ray CT. The results also reaffirm the unique capabilities of benchtop XFCT for simultaneous determination of the spatial distribution and concentration of nonradioactive metallic probes, such as GNPs, within the context of small animal imaging. Overall, this investigation identifies a clear path toward in vivo molecular imaging using benchtop XFCT techniques in conjunction with GNPs and other metallic probes.

  12. Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography

    NASA Astrophysics Data System (ADS)

    Walton, Lucy A.; Bradley, Robert S.; Withers, Philip J.; Newton, Victoria L.; Watson, Rachel E. B.; Austin, Clare; Sherratt, Michael J.

    2015-05-01

    Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons.

  13. Predicting tissue distribution and partitioning in terminal sire sheep using x-ray computed tomography.

    PubMed

    Macfarlane, J M; Lewis, R M; Emmans, G C; Young, M J; Simm, G

    2009-01-01

    The utility of x-ray computed tomography (CT) scanning in predicting carcass tissue distribution and fat partitioning in vivo in terminal sire sheep was examined using data from 160 lambs representing combinations of 3 breeds (Charollais, Suffolk, and Texel), 3 genetic lines, and both sexes. One-fifth of the lambs were slaughtered at each of 14, 18, and 22 wk of age, and the remaining two-fifths at 26 wk of age. The left side of each carcass was dissected into 8 joints with each joint dissected into fat (intermuscular and subcutaneous), lean, and bone. Chemical fat content of the LM was measured. Tissue distribution was described by proportions of total carcass tissue and lean weight contained within the leg, loin, and shoulder regions of the carcass and within the higher-priced joints. Fat partitioning variables included proportion of total carcass fat contained in the subcutaneous depot and intramuscular fat content of the LM. Before slaughter, all lambs were CT scanned at 7 anatomical positions (ischium, midshaft of femur, hip, second and fifth lumbar vertebrae, sixth and eighth thoracic vertebrae). Areas of fat, lean, and bone (mm(2)) and average fat and lean density (Hounsfield units) were measured from each cross-sectional scan. Areas of intermuscular and subcutaneous fat were measured on 2 scans (ischium and eighth thoracic vertebra). Intramuscular fat content was predicted with moderate accuracy (R(2) = 56.6) using information from only 2 CT scans. Four measures of carcass tissue distribution were predicted with moderate to high accuracy: the proportion of total carcass (R(2) = 54.7) and lean (R(2) = 46.2) weight contained in the higher-priced joints and the proportion of total carcass (R(2) = 77.7) and lean (R(2) = 55.0) weight in the leg region. Including BW in the predictions did not improve their accuracy (P > 0.05). Although breed-line-sex combination significantly affected fit of the regression for some tissue distribution variables, the values

  14. Local X-ray Computed Tomography Imaging for Mineralogical and Pore Characterization

    NASA Astrophysics Data System (ADS)

    Mills, G.; Willson, C. S.

    2015-12-01

    Sample size, material properties and image resolution are all tradeoffs that must be considered when imaging porous media samples with X-ray computed tomography. In many natural and engineered samples, pore and throat sizes span several orders of magnitude and are often correlated with the material composition. Local tomography is a nondestructive technique that images a subvolume, within a larger specimen, at high resolution and uses low-resolution tomography data from the larger specimen to reduce reconstruction error. The high-resolution, subvolume data can be used to extract important fine-scale properties but, due to the additional noise associated with the truncated dataset, it makes segmentation of different materials and mineral phases a challenge. The low-resolution data of a larger specimen is typically of much higher-quality making material characterization much easier. In addition, the imaging of a larger domain, allows for mm-scale bulk properties and heterogeneities to be determined. In this research, a 7 mm diameter and ~15 mm in length sandstone core was scanned twice. The first scan was performed to cover the entire diameter and length of the specimen at an image voxel resolution of 4.1 μm. The second scan was performed on a subvolume, ~1.3 mm in length and ~2.1 mm in diameter, at an image voxel resolution of 1.08 μm. After image processing and segmentation, the pore network structure and mineralogical features were extracted from the low-resolution dataset. Due to the noise in the truncated high-resolution dataset, several image processing approaches were applied prior to image segmentation and extraction of the pore network structure and mineralogy. Results from the different truncated tomography segmented data sets are compared to each other to evaluate the potential of each approach in identifying the different solid phases from the original 16 bit data set. The truncated tomography segmented data sets were also compared to the whole

  15. Non-destructive X-ray Computed Tomography (XCT) Analysis of Sediment Variance in Marine Cores

    NASA Astrophysics Data System (ADS)

    Oti, E.; Polyak, L. V.; Dipre, G.; Sawyer, D.; Cook, A.

    2015-12-01

    Benthic activity within marine sediments can alter the physical properties of the sediment as well as indicate nutrient flux and ocean temperatures. We examine burrowing features in sediment cores from the western Arctic Ocean collected during the 2005 Healy-Oden TransArctic Expedition (HOTRAX) and from the Gulf of Mexico Integrated Ocean Drilling Program (IODP) Expedition 308. While traditional methods for studying bioturbation require physical dissection of the cores, we assess burrowing using an X-ray computed tomography (XCT) scanner. XCT noninvasively images the sediment cores in three dimensions and produces density sensitive images suitable for quantitative analysis. XCT units are recorded as Hounsfield Units (HU), where -999 is air, 0 is water, and 4000-5000 would be a higher density mineral, such as pyrite. We rely on the fundamental assumption that sediments are deposited horizontally, and we analyze the variance over each flat-lying slice. The variance describes the spread of pixel values over a slice. When sediments are reworked, drawing higher and lower density matrix into a layer, the variance increases. Examples of this can be seen in two slices in core 19H-3A from Site U1324 of IODP Expedition 308. The first slice, located 165.6 meters below sea floor consists of relatively undisturbed sediment. Because of this, the majority of the sediment values fall between 1406 and 1497 HU, thus giving the slice a comparatively small variance of 819.7. The second slice, located 166.1 meters below sea floor, features a lower density sediment matrix disturbed by burrow tubes and the inclusion of a high density mineral. As a result, the Hounsfield Units have a larger variance of 1,197.5, which is a result of sediment matrix values that range from 1220 to 1260 HU, the high-density mineral value of 1920 HU and the burrow tubes that range from 1300 to 1410 HU. Analyzing this variance allows us to observe changes in the sediment matrix and more specifically capture

  16. Observation of the hollow cathode effect from a dielectric cathode

    NASA Astrophysics Data System (ADS)

    Hwang, Hyeon Seok; Oh, Jin Young; Kim, Youn Sang; Jong Lee, Se; Song, Kie Moon; Baik, Hong Koo

    2010-12-01

    The hollow cathode effect (HCE) is investigated in the dielectric hollow cathode structure in a Ne-Xe mixture at 4%. The influence of the dielectric is shown experimentally by the relationship between voltage and current peaks. The linearity of reduced current density confirms the existence of the HCE and shows that cathode fall has the same value at every pD condition. Varying the pD, the variation in the discharge mode can be measured with IR intensity emitted from the plasma and photographs of discharge in the visible part of the spectra. Voltages and current in the range of 3 kV at 10 µA were used. We suggest an electrode configuration reinforced in cathode sputtering for the display panel and light source using the dielectric hollow cathode discharge (DHCD), and introducing a mechanism of the DHCD mode.

  17. Development of a Radiation Dose Reporting Software for X-ray Computed Tomography (CT)

    NASA Astrophysics Data System (ADS)

    Ding, Aiping

    X-ray computed tomography (CT) has experienced tremendous technological advances in recent years and has established itself as one of the most popular diagnostic imaging tools. While CT imaging clearly plays an invaluable role in modern medicine, its rapid adoption has resulted in a dramatic increase in the average medical radiation exposure to the worldwide and United States populations. Existing software tools for CT dose estimation and reporting are mostly based on patient phantoms that contain overly simplified anatomies insufficient in meeting the current and future needs. This dissertation describes the development of an easy-to-use software platform, “VirtualDose”, as a service to estimate and report the organ dose and effective dose values for patients undergoing the CT examinations. “VirtualDose” incorporates advanced models for the adult male and female, pregnant women, and children. To cover a large portion of the ignored obese patients that frequents the radiology clinics, a new set of obese male and female phantoms are also developed and applied to study the effects of the fat tissues on the CT radiation dose. Multi-detector CT scanners (MDCT) and clinical protocols, as well as the most recent effective dose algorithms from the International Commission on Radiological Protection (ICRP) Publication 103 are adopted in “VirtualDose” to keep pace with the MDCT development and regulatory requirements. A new MDCT scanner model with both body and head bowtie filter is developed to cover both the head and body scanning modes. This model was validated through the clinical measurements. A comprehensive slice-by-slice database is established by deriving the data from a larger number of single axial scans simulated on the patient phantoms using different CT bowtie filters, beam thicknesses, and different tube voltages in the Monte Carlo N-Particle Extended (MCNPX) code. When compared to the existing CT dose software packages, organ dose data in this

  18. Technical Note: spektr 3.0—A computational tool for x-ray spectrum modeling and analysis

    PubMed Central

    Punnoose, J.; Xu, J.; Sisniega, A.; Zbijewski, W.; Siewerdsen, J. H.

    2016-01-01

    Purpose: A computational toolkit (spektr 3.0) has been developed to calculate x-ray spectra based on the tungsten anode spectral model using interpolating cubic splines (TASMICS) algorithm, updating previous work based on the tungsten anode spectral model using interpolating polynomials (TASMIP) spectral model. The toolkit includes a matlab (The Mathworks, Natick, MA) function library and improved user interface (UI) along with an optimization algorithm to match calculated beam quality with measurements. Methods: The spektr code generates x-ray spectra (photons/mm2/mAs at 100 cm from the source) using TASMICS as default (with TASMIP as an option) in 1 keV energy bins over beam energies 20–150 kV, extensible to 640 kV using the TASMICS spectra. An optimization tool was implemented to compute the added filtration (Al and W) that provides a best match between calculated and measured x-ray tube output (mGy/mAs or mR/mAs) for individual x-ray tubes that may differ from that assumed in TASMICS or TASMIP and to account for factors such as anode angle. Results: The median percent difference in photon counts for a TASMICS and TASMIP spectrum was 4.15% for tube potentials in the range 30–140 kV with the largest percentage difference arising in the low and high energy bins due to measurement errors in the empirically based TASMIP model and inaccurate polynomial fitting. The optimization tool reported a close agreement between measured and calculated spectra with a Pearson coefficient of 0.98. Conclusions: The computational toolkit, spektr, has been updated to version 3.0, validated against measurements and existing models, and made available as open source code. Video tutorials for the spektr function library, UI, and optimization tool are available. PMID:27487888

  19. Emission from ferroelectric cathodes

    SciTech Connect

    Sampayan, S.E.; Caporaso, G.J.; Holmes, C.L.; Lauer, E.J.; Prosnitz, D.; Trimble, D.O.; Westenskow, G.A.

    1993-05-17

    We have recently initiated an investigation of electron emission from ferroelectric cathodes. Our experimental apparatus consisted of an electron diode and a 250 kV, 12 ohm, 70 ns pulsed high voltage power source. A planar triode modulator driven by a synthesized waveform generator initiates the polarization inversion and allows inversion pulse tailoring. The pulsed high voltage power source is capable of delivering two high voltage pulses within 50 ns of each other and is capable of operating at a sustained repetition rate of 5 Hz. Our initial measurements indicate that emission current densities above the Child-Langmuir Space Charge Limit are possible. We explain this effect to be based on a non-zero initial energy of the emitted electrons. We also determined that this effect is strongly coupled to relative timing between the inversion pulse and application of the main anode-cathode pulse. We also have initiated brightness measurements of the emitted beam. As in our previous measurements at this Laboratory, we performed the measurement using a pepper pot technique. Beam-let profiles are recorded with a fast phosphor and gated cameras. We describe our apparatus and preliminary measurements.

  20. Cathodic hydrodimerization of nitroolefins

    PubMed Central

    Weßling, Michael

    2015-01-01

    Summary Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C–C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations at the acidic CH bond. Eight 1-aryl-2-nitro-1-propenes have been electrolyzed in an undivided electrolysis cell to afford 2,5-dinitro-3,4-diaryl hexanes in high yield. The 4-methoxy-, 4-trifluoromethyl-, 2-chloro- and 2,6-difluorophenyl group and furthermore the 2-furyl and 2-pyrrolyl group have been applied. The reaction is chemoselective as only the double bond but not the nitro group undergoes reaction, is regioselective as a ß,ß-coupling with regard to the nitro group and forms preferentially two out of six possible diastereomers as major products. PMID:26199673