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Sample records for phosphor physical characterization

  1. Synthesis and characterization of physical properties of Gd2O2S:Pr3+ semi-nanoflower phosphor

    NASA Astrophysics Data System (ADS)

    Bagheri, A.; Rezaee Ebrahim Saraee, Kh.; Shakur, H. R.; Zamani Zeinali, H.

    2016-05-01

    Pure gadolinium oxysulfide phosphor (Gd2O2S) and trivalent praseodymium-doped gadolinium oxysulfide phosphor (Gd2O2S:Pr3+) scintillators with semi-nanoflower crystalline structures were successfully synthesized through a precipitation method and subsequent calcination treatment as a converter for X-ray imaging detectors. The characterization such as the crystal structures and nanostructure of Gd2O2S:Pr3+ scintillator measured by XRD and FeE-SEM experiment. The optical properties of Gd2O2S:Pr3+ scintillator were studied. Luminescence spectra of Gd2O2S:Pr3+ under 320 nm UV excitation show a green emission at near 511 nm corresponding to the 3P0-3H4 of Pr ions. After scintillation properties of synthesized Gd2O2S:Pr3+ scintillator investigated, Gd2O2S:Pr3+ scintillating film fabricated on a glass substrate by a sedimentation method. X-ray imaging of the fabricated scintillators confirmed that the Gd2O2S:Pr3+ scintillator could be used for radiography applications in which good spatial resolution is needed.

  2. Characterization of lithium phosphorous oxynitride thin films

    SciTech Connect

    Yu, Xiaohua; Bates, J.B.; Jellison, G.E. Jr.

    1996-01-01

    Electrical and electrochemical properties of an amorphous thin-film lithium electrolyte, lithium phosphorous oxynitride (Lipon), have been studied with emphasis on the stability window vs Li metal and the behavior of the Li/Lipon interface. Ion conductivity of Lipon exhibits Arrhenius behavior at {minus}26 to +140 C, with a conductivity of 1.7 {times} 10{sup {minus}6}S/cm at 25 C and an activity energy of 0.50 {plus_minus} 0.01 eV. A stability window of 5.5 V was observed with respect to a Li{sup +}/Li reference, and no detectable reaction or degradation was evident at the Li/Lipon interface upon lithium cycling.

  3. Synthesis, characterization and photo luminescence study of Ce3+ activated aluminates based phosphor

    NASA Astrophysics Data System (ADS)

    Selot, Anupam; Aynyas, Mahendra; Tiwari, Manoj; Dev, Kapil

    2016-05-01

    The preparation of phosphor material SrMgAl10O17 with varying concentration of rare earth dopant Ce3+ synthesized by combustion method at 500°C. The synthesized phosphor material characterized for their crystal and nature by XRD measurements. The photoluminescence measurements of phosphor exhibit two PL spectra 389nm and 575 nm in blue and red region, respectively, this is due to crystal field and covalence effect. These results show that concentration quenching occur at 10mol%of Ce dopant. The results suggest the possibility of utilizing as a phosphor may be in solid state lighting.

  4. Synthesis and characterization of Ba3Si6O12N2:Eu(2+) phosphor.

    PubMed

    Fartode, S A; Dhoble, S J

    2016-02-01

    Eu(2+)-doped Ba3Si6O12N2 phosphors were prepared successfully via a modified solid-state diffusion method. The phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence measurements. These phosphors were effectively excited at 355 nm and an intense emission peaking in the range 480 nm to 525 nm in the blue region was observed. The optimized dopant concentration was determined to be 1 mol% of Eu(2+) ion. The colour coordinates for phosphor were found to be (0.196, 0.326) in the blue region. This phosphor may find application for near-ultraviolet (NUV) excited lamp phosphors. The thermoluminescence study shows the complex glow curve. Trapping parameters (activation energy and frequency factor) were calculated for individual deconvoluted peaks by Chen's peak shape method, the initial rise method and the whole glow peak method. PMID:26224417

  5. Materials characterization of phosphoric acid fuel cell system

    NASA Technical Reports Server (NTRS)

    Venkatesh, Srinivasan

    1986-01-01

    The component materials used in the fabrication of phosphoric acid fuel cells (PAFC) must have mechanical, chemical, and electrochemical stability to withstand the moderately high temperature (200 C) and pressure (500 kPa) and highly oxidizing nature of phosphoric acid. This study discusses the chemical and structural stability, performance and corrosion data on certain catalysts, catalyst supports, and electrode support materials used in PAFC applications.

  6. Characterization of Manganese-doped Willemite Green Phosphor Gel Powders

    NASA Astrophysics Data System (ADS)

    Tsai, Mu-Tsun; Lin, Yi-Hsun; Yang, Jing-Ru

    2011-10-01

    Nanocrystalline manganese-doped zinc silicate (Zn2-xMnxSiO4 x = 0-12.0 mol%) powder phosphors were prepared by the sol-gel process. Zinc chloride, tetraethylorthosilicate, and manganese chloride were employed as precursors. The influences of water concentration on the crystallization and photoluminescence of the phosphors were investigated. Single-phase wiemite (α-Zn2SiO4) started to crystallize after calcining at 600°C for powders derived from low-water-conen so, whie β-Zn2SiO4 became the dominated phase with residual ZnO trace for high-water-content sol derived powders as calcining at below 900 °C. On firing at 800°-1200°C, the resulting phosphors had the average crystallite sizes of 15~38 nm. With various content of water and heating the powders at 800°C, the prepared phosphors exhibited yellow and green emission peaking at 556 and 524 nm, respectively. Upon heating at 1200 °C, powder phosphors exhibited prominent photoluminescence emission bands peaked at 522~526 nm, depending on the doping content. The luminous efficiency has been investigated as a function of dopant content and heating temperature.

  7. From natural attapulgite to phosphor materials: Characterization, photoluminescence and structure

    SciTech Connect

    Wang, Wenjie; Gu, Zheng; Gao, Xiuping; Jiang, Huie; Liu, Weisheng

    2014-08-15

    Highlights: • Sr{sub 2.965}Al{sub 0.08}Si{sub 0.92}O{sub 5}:0.025Ce{sup 3+}, 0.01Eu{sup 2+} phosphor was synthesized from natural attapulgite. • Pure Sr{sub 3}SiO{sub 5} phase can be easily obtained. • It provides a new application field as phosphor for natural attapulgite. - Abstract: Sr{sub 2.965}Al{sub 0.08}Si{sub 0.92}O{sub 5}:0.025Ce{sup 3+}, 0.01Eu{sup 2+} (SrAlSiO:Ce{sup 3+}, Eu{sup 2+}) phosphor from natural attapulgite (ATP) was synthesized by solid-state reaction method. For the use of ATP as a source of Si and Al, pretreatment process including mechanical grinding and acid leaching were involved. X-ray diffraction patterns confirmed the formation of silicates in a wide temperature field, whereas Sr{sub 3}SiO{sub 5} within a single step. The ATP fibers were tuning into phosphor particles (about 1.5–3.0 μm) after calcination. Furthermore, photoluminescence spectra of the SrAlSiO:Ce{sup 3+}, Eu{sup 2+} phosphor was also in good agreement with the literature results, indicating a promising potential application as an effective candidate for warm-white LEDs materials.

  8. Characterization and luminescence properties of CaMgSi2O6:Eu2+ blue phosphor.

    PubMed

    Chandrakar, P; Baghel, R N; Bisen, D P; Chandra, B P

    2015-11-01

    A blue CaMgSi2O6:Eu(2+) phosphor was prepared by the solid-state reaction method and the phosphor characterized in terms of crystal structure, particle size, photoluminescence (PL), thermoluminescence (TL) and mechanoluminescence (ML) properties using X-ray diffraction (XRD), transmission electron microscopy (TEM), PL spectroscopy, TLD reader and ML impact technique. The XRD result shows that phosphor is formed in a single phase and has a monoclinic structure with the space group C2/c. Furthermore, the PL excitation spectra of Eu(2+) -doped CaMgSi2 O6 phosphor showed a strong band peak at 356 nm and the PL emission spectrum has a peak at 450 nm. The depths and frequency factors of trap centers were calculated using the TL glow curve by deconvolution method in which the trap depths were found to be 0.48 and 0.61 eV. The formation of CaMgSi2O6:Eu(2+) phosphor was confirmed by Fourier transform infrared spectroscopy. The ML intensity increased linearly with the impact velocity of the piston used to deform the phosphor. It was shown that the local piezoelectricity-induced electron bombardment model is responsible for the ML emission. Finally, the optical properties of CaMgSi2O6:Eu(2+) phosphors are discussed. PMID:25665136

  9. Characterization and luminescence properties of Sr3Gd): Sm3+ orange-red phosphor

    NASA Astrophysics Data System (ADS)

    Yang, Zaifa; Xu, Denghui; Sun, Jiayue; Sun, Yumei; Du, Haiyan

    2015-10-01

    Reddish-orange emitting phosphors, Sr3Gd): Sm3+, were successfully synthesized by a conventional solid-state reaction. The crystal structure of the phosphors was characterized by x-ray diffraction. The excitation spectra and emission spectra were utilized to characterize the luminescence properties of the as-prepared phosphors. The results show that the phosphor consisted of some sharp emission peaks of Sm3+ ions centered at 564, 600, 647, and 707 nm, respectively. The critical distance of Sr3Gd0.93): 0.07Sm3+ was calculated to be 19.18 Å and the lifetime value of the sample was 1.63 ms. The band gap of Sr3Gd) was estimated to be about 2.74 eV from the diffuse reflection spectrum. The optimum doping concentration is 7 mol. % and the quenching occurs via dipole-dipole interaction according to Dexter's theory. The Commission Internationale de L'Eclairage value of Sr3Gd): Sm3+ phosphors presented that it has high color purity. These results indicated that the Sr3Gd): Sm3+ may be a promising reddish-orange emitting phosphor for cost-effective near ultraviolet white light-emitting diodes.

  10. Synthesis and characterization of erbium-doped YAlO3 phosphor.

    PubMed

    Baig, Huma Nazli; Saluja, Jagjeet Kaur; Dhoble, S J

    2016-03-01

    In the yttrium aluminium system, the YAlO3 phosphor is a prominent host because of the yttrium aluminium ratio (1:1). Phosphor was synthesized by the solid-state reaction method at variable concentrations of erbium (0.1-2.5 mol%). This method is suitable for large-scale production and is a less time-consuming method when compared with the soft synthesis method. The prepared sample was characterized by X-ray diffraction technique and the crystallite size was calculated by Scherer's formula. Vibrational and bending analysis of prepared phosphor for optimized concentration of erbium ion is described based on the Fourier transform infrared spectroscopic technique. The photoluminescence (PL) emission spectra of prepared phosphor for variable concentrations of erbium ion were recorded and the excitation spectrum was found to be at 291 nm with three shoulder peaks at 305, 270 and 242 nm. For 291 nm excitation, the emission spectrum was found at 546 nm and 552 nm. PL intensity increased with increasing concentrations of erbium and after 2 mol% emission intensity decreased due to concentration quenching. Spectrophotometric determination of YAlO3:Er(3+) is described by CIE co-ordinates and shows an intense emission in the green region such that the prepared phosphor can act as a single host for green light emission. Thermoluminescence glow curve analysis of the YAlO3:Er(3+) phosphor was recorded for different ultraviolet (UV) light exposures and gamma exposure. Different gamma doses 0.5-2 kGy show a linear response. Kinetic parameters were calculated by the peak shape method. PMID:26455914

  11. Mound facility physical characterization

    SciTech Connect

    Tonne, W.R.; Alexander, B.M.; Cage, M.R.; Hase, E.H.; Schmidt, M.J.; Schneider, J.E.; Slusher, W.; Todd, J.E.

    1993-12-01

    The purpose of this report is to provide a baseline physical characterization of Mound`s facilities as of September 1993. The baseline characterizations are to be used in the development of long-term future use strategy development for the Mound site. This document describes the current missions and alternative future use scenarios for each building. Current mission descriptions cover facility capabilities, physical resources required to support operations, current safety envelope and current status of facilities. Future use scenarios identify potential alternative future uses, facility modifications required for likely use, facility modifications of other uses, changes to safety envelope for the likely use, cleanup criteria for each future use scenario, and disposition of surplus equipment. This Introductory Chapter includes an Executive Summary that contains narrative on the Functional Unit Material Condition, Current Facility Status, Listing of Buildings, Space Plans, Summary of Maintenance Program and Repair Backlog, Environmental Restoration, and Decontamination and Decommissioning Programs. Under Section B, Site Description, is a brief listing of the Site PS Development, as well as Current Utility Sources. Section C contains Site Assumptions. A Maintenance Program Overview, as well as Current Deficiencies, is contained within the Maintenance Program Chapter.

  12. Physical evaluation of a needle photostimulable phosphor based CR mammography system

    SciTech Connect

    Marshall, Nicholas W.; Lemmens, Kim; Bosmans, Hilde

    2012-02-15

    approximately 3 greater than for the powder CR plates. At 28 kV W/Rh, 2 mm Al, peak DQE for the needle CR system was 0.45 against a value of 0.50 for the a-Se detector. The needle CR detector reached the Acceptable limit for 0.1 mm details in the European Guidelines at a mean glandular dose (MGD) of approximately 1.31 mGy imaged at 28 kV Mo/Rh, compared to figures of 2.19 and 1.43 mGy for the single sided and dual sided readout powder CR systems. The a-Se detector could reach the limit at 0.65 mGy using a 28 kV W/Rh spectrum, while the needle CR system required 1.09 mGy for the same spectrum. Conclusions: Imaging performance for the needle CR phosphor technology, characterized using MTF and DQE and threshold gold thickness demonstrated a clear improvement compared to both single and dual sided reading powder phosphor based CR systems.

  13. Characterization and evaluation of a photostimulable phosphor x-ray imaging system

    SciTech Connect

    Yocky, D.A.

    1988-01-01

    This study presents the characterization and evaluation of a new radiological imagining modality, Toshiba Computed Radiography (TCR) 201. The characteristics of the TCR storage phosphor imaging plates such as energy-dependent x-ray quantum efficiency, stored signal decay, low exposure rate signal build-up, and spontaneous and stimulated gain measures are presented. The TCR 201 system is characterized by the signal transfer curve, the total root-mean-squared (rms) output noise, the signal-to-noise ratio, the modulation transfer function (MTF), its noise power spectrum (NPS), and the detective quantum efficiency (DQE). The system rms noise is photon-limited for exposures less than 1.0 mR, but has contributions from phosphor structure and quantization noise for exposures higher than 1.0 mR. The phosphor's information factor is shown to explain deviations from ideal photon-limited noise for exposures of less than 1.0 mR. The MTF of the system is measured for standard imaging plates, 10% at 2.8 lp/mm. An expression for the NPS is statistically derived, and experimental measurements confirm the expression and show an increase in uncorrelated noise power above 1.0 mR which is consistent with rms measurements. Expressions for the DQE are presented.

  14. Synthesis and characterization of new biopolymeric microcapsules containing DEHPA-TOPO extractants for separation of uranium from phosphoric acid solutions.

    PubMed

    Outokesh, Mohammad; Tayyebi, Ahmad; Khanchi, Alireza; Grayeli, Fatemeh; Bagheri, Ghodrat

    2011-01-01

    A novel microcapsule adsorbent for separation of uranium from phosphoric acid solutions was developed by immobilizing the di(2-ethylhexyl) phosphoric acid-trioctyl phosphine oxide extractants in the polymeric matrix of calcium alginate. Physical characterization of the microcapsules was accomplished by scanning electron microscopy and thermogravimetric techniques. Equilibrium experiments revealed that both ion exchange and solvent extraction mechanisms were involved in the adsorption of [Formula: see text] ions, but the latter prevailed in a wider range of acid concentration. According to the results of kinetics study, at low acidity level, the rate controlling step was slow chemical reaction of [Formula: see text] ions with the microdroplets of extractant, whereas it changed to intraparticle diffusion at higher acid concentration. The study also attempted identification of the diffusion paths of the ions within the microcapsules, and the mechanism of change of mass transfer rate during the uptake process. The prepared microcapsules preserved their entire capacity after three cycles of adsorption, and their breakthrough behaviour was well fitted by a new formula derived from shrinking core model. PMID:21545316

  15. Characterization of imaging performances of gadolinium-oxysulfide phosphors made for X-ray imaging by using a sedimentation process

    NASA Astrophysics Data System (ADS)

    Yun, Seungman; Han, Jong Chul; Joe, Okla; Ko, Jong Soo; Kim, Young Soo; Kim, Ho Kyung

    2012-02-01

    The development of a pixel-structured scintillator has recently been exploited to confine optical transport onto a corresponding photodiode pixel. This conceptual design of scintillators may provide high detection efficiency while preserving high spatial resolution in digital X-ray imaging detector systems. The sedimentation approach is one method to fill gadolinium-oxysulfide phosphors into a pixel-structured micro-well array. To fully understand the X-ray imaging characteristics of a pixel-structured design with sedimented gadolinium-oxysulfide phosphors, the imaging performance of gadolinium-oxysulfide phosphor layers made by using sedimentation should be characterized in advance. We have fabricated gadolinium-oxysulfide phosphor screens by using a simple sedimentation method. In order to characterize the imaging performances of the developed phosphor screens, we overlaid them onto a photodiode array with a pixel pitch of 48 microns and thus completed indirect-conversion X-ray imaging detectors. The imaging performance of the detector was investigated in terms of the modulation-transfer function (MTF), the noise-power spectrum, and the detective quantum efficiency (DQE). The results were compared with those of detectors employing commercial phosphor screens. Although the developed screen was about 1.5 times thicker than the commercial one, the X-ray sensitivity was comparable to that of the commercial phosphor. The MTF performance was worse than that of the commercial screen, and that MTF performance also governed the DQE performance of the detector over the entire spatial-frequency band. If the sedimented phosphors are pixel-structured with micro-well arrays, however, the MTF performance can be defined by using only the pixel size. Therefore, a design to enhance the X-ray sensitivity for the sedimentation method should be considered.

  16. Degradation Physics of High Power LEDs in Outdoor Environment and the Role of Phosphor in the degradation process

    NASA Astrophysics Data System (ADS)

    Singh, Preetpal; Tan, Cher Ming

    2016-04-01

    A moisture- electrical – temperature (MET) test is proposed to evaluate the outdoor reliability of high power blue LEDs, with and without phosphor, and to understand the degradation physics of LEDs under the environment of combined humidity, temperature and electrical stresses. The blue LEDs with phosphor will be the high power white LEDs. Scanning acoustic microscopy is used to examine the resulted delamination during this test for the LEDs. The degradation mechanisms of blue LEDs (LEDs without phosphor) and white LEDs (LEDs with phosphor) are found to be different, under both the power on (i.e. with 350 mA through each LED) and power off (i.e. without current supply) conditions. Difference in the coefficient of thermal expansion between the molding part and the lens material as well as the heat generated by the phosphor layer are found to account for the major differences in the degradation mechanisms observed. The findings indicate that the proposed MET test is necessary for the LED industry in evaluating the reliability of LEDs under practical outdoor usage environment.

  17. Degradation Physics of High Power LEDs in Outdoor Environment and the Role of Phosphor in the degradation process.

    PubMed

    Singh, Preetpal; Tan, Cher Ming

    2016-01-01

    A moisture- electrical - temperature (MET) test is proposed to evaluate the outdoor reliability of high power blue LEDs, with and without phosphor, and to understand the degradation physics of LEDs under the environment of combined humidity, temperature and electrical stresses. The blue LEDs with phosphor will be the high power white LEDs. Scanning acoustic microscopy is used to examine the resulted delamination during this test for the LEDs. The degradation mechanisms of blue LEDs (LEDs without phosphor) and white LEDs (LEDs with phosphor) are found to be different, under both the power on (i.e. with 350 mA through each LED) and power off (i.e. without current supply) conditions. Difference in the coefficient of thermal expansion between the molding part and the lens material as well as the heat generated by the phosphor layer are found to account for the major differences in the degradation mechanisms observed. The findings indicate that the proposed MET test is necessary for the LED industry in evaluating the reliability of LEDs under practical outdoor usage environment. PMID:27052103

  18. Degradation Physics of High Power LEDs in Outdoor Environment and the Role of Phosphor in the degradation process

    PubMed Central

    Singh, Preetpal; Tan, Cher Ming

    2016-01-01

    A moisture- electrical – temperature (MET) test is proposed to evaluate the outdoor reliability of high power blue LEDs, with and without phosphor, and to understand the degradation physics of LEDs under the environment of combined humidity, temperature and electrical stresses. The blue LEDs with phosphor will be the high power white LEDs. Scanning acoustic microscopy is used to examine the resulted delamination during this test for the LEDs. The degradation mechanisms of blue LEDs (LEDs without phosphor) and white LEDs (LEDs with phosphor) are found to be different, under both the power on (i.e. with 350 mA through each LED) and power off (i.e. without current supply) conditions. Difference in the coefficient of thermal expansion between the molding part and the lens material as well as the heat generated by the phosphor layer are found to account for the major differences in the degradation mechanisms observed. The findings indicate that the proposed MET test is necessary for the LED industry in evaluating the reliability of LEDs under practical outdoor usage environment. PMID:27052103

  19. Green Phosphors

    NASA Astrophysics Data System (ADS)

    Singh, Vijay; Chakradhar, R. P. S.; Rao, J. L.; Dhoble, S. J.; Kim, S. H.

    2014-11-01

    Manganese-doped LaMgAl11O19 powder has been prepared by an easy combustion method. Powder x-ray diffraction and scanning electron microscopy have been used to characterize the as-prepared phosphor. The electron paramagnetic resonance (EPR) spectrum of LaMgAl11O19:Mn2+ phosphor exhibits six-line hyperfine structure centered at g ≈ 1.973. The number of spins participating in resonance ( N) and the paramagnetic susceptibility ( χ) for the resonance signal at g ≈ 1.973 have been calculated as a function of temperature. The photoluminescence spectrum exhibits green emission at 516 nm, which is attributed to 4T1 → 6A1 transition of Mn2+ ions. From EPR and luminescence studies, it is observed that Mn2+ ions occupy Mg2+ sites and Mn2+ ions are located at tetrahedral sites in the prepared phosphors.

  20. Comparison of different computed radiography systems: Physical characterization and contrast detail analysis

    SciTech Connect

    Rivetti, Stefano; Lanconelli, Nico; Bertolini, Marco; Nitrosi, Andrea; Burani, Aldo; Acchiappati, Domenico

    2010-02-15

    Purpose: In this study, five different units based on three different technologies--traditional computed radiography (CR) units with granular phosphor and single-side reading, granular phosphor and dual-side reading, and columnar phosphor and line-scanning reading--are compared in terms of physical characterization and contrast detail analysis. Methods: The physical characterization of the five systems was obtained with the standard beam condition RQA5. Three of the units have been developed by FUJIFILM (FCR ST-VI, FCR ST-BD, and FCR Velocity U), one by Kodak (Direct View CR 975), and one by Agfa (DX-S). The quantitative comparison is based on the calculation of the modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). Noise investigation was also achieved by using a relative standard deviation analysis. Psychophysical characterization is assessed by performing a contrast detail analysis with an automatic reading of CDRAD images. Results: The most advanced units based on columnar phosphors provide MTF values in line or better than those from conventional CR systems. The greater thickness of the columnar phosphor improves the efficiency, allowing for enhanced noise properties. In fact, NPS values for standard CR systems are remarkably higher for all the investigated exposures and especially for frequencies up to 3.5 lp/mm. As a consequence, DQE values for the three units based on columnar phosphors and line-scanning reading, or granular phosphor and dual-side reading, are neatly better than those from conventional CR systems. Actually, DQE values of about 40% are easily achievable for all the investigated exposures. Conclusions: This study suggests that systems based on the dual-side reading or line-scanning reading with columnar phosphors provide a remarkable improvement when compared to conventional CR units and yield results in line with those obtained from most digital detectors for radiography.

  1. Synthesis and characterization of tunable coumarin- linked glasses as new class of organic/inorganic phosphors

    SciTech Connect

    Luridiana, Alberto; Pretta, Gianluca; Secci, Francesco; Frongia, Angelo; Chiriu, Daniele; Carbonaro, Carlo Maria; Corpino, Riccardo; Ricci, Pier Carlo

    2014-10-21

    It is well known that stilbene with a trans conformation is highly fluorescent. From the viewpoint of molecular structure, coumarins bear a carbon-carbon double bond which is fixed as trans conformation as in trans-stilbene through a lactone structure. This can help to avoid the trans-cis transformation of the double bond under ultraviolet (UV) irradiation as observed in stilbene compounds and results in strong fluorescence and high fluorescence quantum yield and photostability in most of coumarin derivatives. Herein we report some preliminary results about the synthesis and spectroscopic characterization of tunable coumarins and the development of a new linkage protocol for the obtainment of monolayer coumarin-covalently linked glasses. The resulting organic/inorganic coumarin/silica based Self-Assembled Monolayer (SMA) film is proposed as new phosphors for the substituting of critical raw materials, like rare earths, in photonics applications.

  2. [Preparation and characterization of upconversion phosphor based on AlF3-YbF3 : Er3+].

    PubMed

    Zhou, He-Feng; Zhang, Shu-Quan; Wang, Hua; Li, Jie; Wang, Li; Wang, Shu-Hao; Lin, Wen-Jing; Lin, Hong-Li

    2013-01-01

    In the present paper, AlF3-YbF3 : Er3+ was prepared by high temperature solid phase reaction, and the concentration effect of Er3+ on luminous intensity of phosphors was studied. The crystal structures of the phosphors were characterized by means of X-ray diffraction (XRD), and the upconversion luminescence properties of phosphor were studied by fluorescence emission spectra. Upon 980 nm excitation, when the Er3+ concentration was fixed to be 0.7 mol%, the maximum red emission intensities can be obtained in the sample. Furthermore, the research results showed that the fitted slope for red transition emission was 2.24, indicating that red emission is due to a two-photon excitation process. PMID:23586216

  3. Synthesis, characterization and TL response of Ce{sup 3+} activated BaMgAl{sub 10}O{sub 17} phosphor

    SciTech Connect

    Selot, Anupam; Aynyas, Mahendra; Tiwari, Manoj; Dev, Kapil

    2015-06-24

    Phosphor material BaMgAl{sub 10}O{sub 17} with varying concentration of rare earth Ce{sup 3+} synthesis by combustion method at 500°C. The synthesized phosphor material characterized for their crystallinity and nature by XRD measurements. The thermoluminescecne response of phosphor exhibit TL spectra at 204°c and detailed analysis of kinetic parameter by de convoluted curve. These results show that concentration quenching occur at 5mol% of Ce dopant. The results suggest the possibility of utilizing as a phosphor may be in UV dosimeter and solid state lighting.

  4. Synthesis, characterization and optical properties of Ce{sup 3+} activated CaMgAl{sub 10}O{sub 17} phosphor

    SciTech Connect

    Selot, Anupam; Aynyas, Mahendra; Tiwari, Manoj; Dev, Kapil

    2014-04-24

    Phosphor material CaMgAl{sub 10}O{sub 17} with varying concentration of rare earth Ce{sub 3+} synthesis by combustion method at 500°C. The synthesized phosphor material characterized for their crystallinity and nature by XRD measurements. The photoluminescence measurements of phosphor exhibit mainly two PL spectra 382nm and 575 nm in blue and red region, respectively, this is due to crystal field and covalence effect. These results show that concentration quenching occur at 5mol° of Ce dopant. The results suggest the possibility of utilizing as a phosphor may be in solid state lighting.

  5. Synthesis and characterization of Tb{sup 3+} doped MgSrAl{sub 10}O{sub 17} green emitting phosphor

    SciTech Connect

    Panse, V. R.; Dhoble, S. J.; Kokode, N. S.

    2013-12-16

    There is a growing demand for economically viable phosphors for newly emerging display devices with on-going technological advancements. Various aluminates are used as hosts for doping rare earth ions in luminescent applications. Green emitting terbium-ion-doped MgSrAl{sub 10}O{sub 17} phosphor prepared using the combustion method. An efficient phosphor can be prepared by this method at around 550°C in a very short time of few minutes. Further phosphor was analyzed by XRD for the confirmation of desired phase and purity. The morphology and structure of the phosphor were characterized by Scanning electron microscopy. The vibrational properties of MgSrAl{sub 10}O{sub 17} phosphor was studied by FTIR.

  6. Rare earth phosphors and phosphor screens

    DOEpatents

    Buchanan, Robert A.; Maple, T. Grant; Sklensky, Alden F.

    1981-01-01

    This invention relates to rare earth phosphor screens for converting image carrying incident radiation to image carrying visible or near-visible radiation and to the rare earth phosphor materials utilized in such screens. The invention further relates to methods for converting image carrying charged particles to image carrying radiation principally in the blue and near-ultraviolet region of the spectrum and to stabilized rare earth phosphors characterized by having a continuous surface layer of the phosphors of the invention. More particularly, the phosphors of the invention are oxychlorides and oxybromides of yttrium, lanthanum and gadolinium activated with trivalent cerium and the conversion screens are of the type illustratively including x-ray conversion screens, image amplifier tube screens, neutron imaging screens, cathode ray tube screens, high energy gamma ray screens, scintillation detector screens and screens for real-time translation of image carrying high energy radiation to image carrying visible or near-visible radiation.

  7. Synthesis and characterization of YAG:Ce phosphors for white LEDs

    NASA Astrophysics Data System (ADS)

    Tucureanu, V.; Matei, A.; Avram, A. M.

    2015-12-01

    Worldwide commercial interest in the production of cerium doped yttrium aluminium garnet (YAG:Ce) phosphors is reflected in the widespread use of white light emitting devices. Despite of the fact that YAG:Ce is considered a "cool phosphor" it is the most important in white LED technology. This article reviews the developed techniques for producing phosphors with superior photoluminescence efficiency, including solid-state reaction, sol-gel and (co)precipitation methods. Also, by co-doping with rare earth elements, a red/blue shift is reached in the spectrum. The characteristics of YAG:Ce phosphors are investigated because the properties of the phosphors are strongly influenced by the synthesis routes and the sintering temperature treatment. After the phase analysis, morphology and emission studies of the phosphors there may be seen the conditions when the transition from the amorphous phase to the crystalline phase appears, when luminescent properties are influenced by the crystalline form, purity, average size of the particles, co-doping and so on.

  8. Luminescence and advanced mass spectroscopic characterization of sodium zinc orthophosphate phosphor for low-cost light-emitting diodes.

    PubMed

    Mishra, Savvi; Swati, G; Rajesh, B; Tyagi, Kriti; Gahtori, Bhasker; Sivaiah, B; Vijayan, N; Dalai, M K; Dhar, A; Auluck, S; Jayasimhadri, M; Haranath, D

    2016-03-01

    A new rare-earth-free NaZnPO4 :Mn(2+) (NZP:Mn) phosphor powder has been developed by our group and investigated meticulously for the first time using secondary ion mass spectroscopy and chemical imaging techniques. The studies confirmed the effective incorporation of Mn(2+) into the host lattice, resulting in an enhancement of photoluminescence intensity. Phase purity has been verified and structure parameters have been determined successfully by Rietveld refinement studies. The NZP:Mn phosphor powder exhibits strong absorption bands in the ultraviolet and visible (300-470 nm) regions with a significant broad yellow-green (~543 nm) emission due to the characteristic spin forbidden d-d transition ((4) T1 →(6) A1 ) of Mn(2+) ions, indicating weak crystal field strength at the zinc-replaced manganese site. The decay constants are a few milliseconds, which is a pre-requisite for applications in many display devices. The results obtained suggest that this new phosphor powder will find many interesting applications in semiconductor physics, as cost-effective light-emitting diodes (LEDs), as solar cells and in photo-physics. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26198805

  9. Synthesis and characterization of Gd 2O 3:Eu 3+ phosphor nanoparticles by a sol-lyophilization technique

    NASA Astrophysics Data System (ADS)

    Louis, C.; Bazzi, R.; Flores, Marco A.; Zheng, W.; Lebbou, K.; Tillement, O.; Mercier, B.; Dujardin, C.; Perriat, P.

    2003-07-01

    The characterization and luminescence properties of nanostructured Gd 2O 3:Eu 3+ phosphors synthesized by a sol-lyophilization process are presented. After preparation of gadolinium-based sols from gadolinium nitrate and ammonium hydroxide, the so-prepared sols were freeze dried at -10°C and calcinated at different temperatures. For temperatures lower than 1300 K, highly crystalline samples with the cubic structure can be obtained without concomitant grain growth of the particles (<50 nm). The luminescence spectra contain all possible transitions of Eu 3+ with C2 symmetry and present two major features: an increase of the luminescence efficiencies of the phosphors in comparison with that obtained by solid-state reaction and the presence of an additional peak at about 609 nm at the vicinity of the 5D0→ 7F0…4 transition.

  10. Structural characterization of Er(3+),Yb(3+)-doped Gd2O3 phosphor, synthesized using the solid-state reaction method, and its luminescence behavior.

    PubMed

    Tamrakar, Raunak Kumar; Bisen, D P; Brahme, Nameeta

    2016-02-01

    We report the synthesis and structural characterization of Er(3+),Yb(3+)-doped Gd2O3 phosphor. The sample was prepared using the conventional solid-state reaction method, which is the most suitable method for large-scale production. The prepared phosphor sample was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermoluminescence (TL), photoluminescence (PL) and CIE techniques. For PL studies, the excitation and emission spectra of Gd2O3 phosphor doped with Er(3+) and Yb(3+) were recorded. The excitation spectrum was recorded at a wavelength of 551 nm and showed an intense peak at 276 nm. The emission spectrum was recorded at 276 nm excitation and showed peaks in all blue, green and red regions, which indicate that the prepared phosphor may act as a single host for white light-emitting diode (WLED) applications, as verified by International de I'Eclairage (CIE) techniques. From the XRD data, the calculated average crystallite size of Er(3+) and Yb(3+) -doped Gd2O3 phosphor is ~ 38 nm. A TL study was carried out for the phosphor using UV irradiation. The TL glow curve was recorded for UV, beta and gamma irradiations, and the kinetic parameters were also calculated. In addition, the trap parameters of the prepared phosphor were also studied using computerized glow curve deconvolution (CGCD). PMID:25892294

  11. Characterization of novel powder and thin film RGB phosphors for field emission display application

    SciTech Connect

    Chakhovskoi, A.G.; Hunt, C.E.; Malinowski, M.E.; Felter, T.E.; Talin, A.A.

    1997-03-01

    The spectral response, brightness, and outgassing characteristics of new, low-voltage phosphors for application in field emission flat panel displays, are presented. The tested phosphor materials include combustion synthesized powders and thin films prepared by rf diode or magnetron sputtering, laser ablation, and molecular beam epitaxy. These cathodoluminescent materials are tested with e-beam excitation at currents up to 50 {mu}A within the 200{endash}2000 V (e.g., {open_quotes}low-voltage{close_quotes}) and 3{endash}8 kV (e.g., {open_quotes}medium-voltage{close_quotes}) ranges. The spectral coordinates are compared to commercial low-voltage phosphors. Phosphor outgassing, as a function of time, is measured with a residual gas analyzer at fixed 50 {mu}A beam current in the low-voltage range. We find that levels of outgassing stabilize to low values after the first few hours of excitation. The desorption rates measured for powder phosphor layers with different thicknesses are compared to desorption from thin films. {copyright} {ital 1997 American Vacuum Society.}

  12. Characterization of novel powder and thin film RGB phosphors for field emissions display application

    SciTech Connect

    Chakhovskoi, A.G.; Hunt, C.E.; Malinowski, M.E.; Felter, T.E.; Talin, A.A.

    1996-12-31

    The spectral response, brightness and outgassing characteristics of new, low-voltage phosphors for application in field-emission flat-panel displays, are presented. The tested phosphor materials include combustion synthesized powders and thin films prepared by RF-diode or magnetron sputtering, laser ablation and molecular beam epitaxy. These cathodoluminescent materials are tested with e-beam excitation at currents up to 50 {mu}A within the 200-2000V (e.g. {open_quotes}low-voltage{close_quotes}) and 3-8 kV (e.g. {open_quotes}medium voltage{close_quotes}) ranges. The spectral coordinates are compared to commercial low-voltage P22 phosphors. Phosphor outgassing, as a function of time is measured with a residual gas analyzer at fixed 50 {mu}A beam current in the low-voltage range. We find that levels of outgassing stabilize to low values after the first few hours of excitation. The desorption rates measured for powder phosphor layers with different thickness are compared to desorption from thin films.

  13. Synthesis, characterization and application of luminescent quantum dots and microcrystalline phosphors

    NASA Astrophysics Data System (ADS)

    Kang, Zhitao

    A phosphor is a substance which emits light when excited by radiation. For traditional powder phosphors impurity elements are usually incorporated into the host material to act as the luminescent centers. The fluorescent quantum dot (QD) is a new kind of phosphor, "quantum phosphor", with an extremely small size of 1˜10 nm and size dependent tunable emission color from the same pure semiconductor material due to quantum confinement. In this research Si QDs embedded in SiOx or SiNx thin films, which could emit light in the entire visible range from 440 nm to 840 nm by controlling their size and/or their matrix, were synthesized by evaporation or plasma enhanced chemical vapor deposition (PECVD) techniques. Various shades of "white" could be obtained from multi-layered SiNx film structures by controlling the size of Si QDs and layer thickness. It was shown that the combination of these films can produce white emission spectra with superior color rendering properties compared to conventional fluorescent tubes. Such Si-based QDs can be used as down-converting phosphors to coat a blue/UV LED to generate white light, providing a less expensive fabrication process to obtain advanced solid state lighting devices that, compared to conventional fragile lamps, are more efficient, longer lived, and provide a full sunlight spectrum. As a supplement, free CdTe QDs with emission colors spanning 520˜700 nm and quantum efficiency (QE) up to 54%, were synthesized using a colloidal chemical method for white LED applications. White PL and a range of emission colors were obtained from mixed CdTe QD samples excited by a 420 nm blue LED. Another part of this research was to develop a new x-ray powder phosphor, ZnTe:O, for biological imaging applications used in CCD-based synchrotron x-ray detectors. As a lower band-gap semiconductor, ZnTe could theoretically achieve a higher x-ray luminescence efficiency than its counterpart, ZnSe, which is an x-ray phosphor host with the highest known

  14. Synthesis, PL characterizations and concentration quenching effect in Dy(3+) and Eu(3+) activated LiCaBO3 phosphor.

    PubMed

    Kharabe, V R; Oza, Abha H; Dhoble, S J

    2015-06-01

    LiCaBO3 :Dy(3+) /Eu(3+) phosphors were synthesized by a solid-state reaction. The synthesized materials were characterized using powder X-ray diffraction pattern (XRD) for confirmation. All the structural parameters were calculated from the XRD data. Scanning electron microscopy (SEM) images showed rod-like morphology. Photoluminescence (PL) emission spectra showed two emissions (484 and 577 nm) in Dy(3+) -doped LiCaBO3 :Dy(3+) phosphors with the concentration quenching effect and the critical distance was calculated to be about 22.76 Å. LiCaBO3 :Eu(3+) phosphor was effectively excited by a near-UV light of 392 nm. The emission spectra exhibited the transition from (5) D0 level to (7) FJ (J = 0-2) with main emission at 614 nm, which comes from the electrodipole transition because of the asymmetric point group. The quenching concentration of Eu(3+) is about 0.2 mol%, and the critical distance was calculated to be about 38.93 Å. PMID:25137055

  15. Synthesis and Optical Characterization of Red-Emitting BaTa2O6:Eu(3+) Phosphors.

    PubMed

    İlhan, Mustafa; Ekmekçi, Mete Kaan; Mergen, Ayhan; Yaman, Cemalettin

    2016-09-01

    Undoped and Eu(3+) doped BaTa2O6 phosphors were synthesized via solid state reaction method and characterized by using XRD, SEM-EDS and photoluminescence (PL) analyses. The XRD results revealed that the crystal structure of BaTa2O6 allowed up to 10 mol% levels of Eu(3+) ions due to the TTB characteristic network of adjacent octahedrals. SEM-EDS analyses confirmed the formation of BaTa2O6 structure and EuTaO4 secondary phase. BaTa2O6:Eu(3+) phosphors exhibited orange and red emissions at 592.2 nm and 615.7 nm in the visible region respectively. The Commission Internationale d'Eclairage (CIE) chromaticity coordinates of the BaTa2O6:Eu(3+) phosphors that excited at λ ex = 400 nm ranged from orangish-red to pinkish-red depending on increasing Eu(3+) concentration. PMID:27325113

  16. Synthesis and characterization of Zn2GeO4:Mn2+ phosphor for field emission displays

    NASA Astrophysics Data System (ADS)

    Zhang, Qiuhong; Wang, Jing

    2012-09-01

    Zn2-2 x Mn2 x GeO4 ( x=0, 0.001, 0.01) phosphors were prepared by conventional solid state reaction technique. X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), diffuse reflection spectra, photoluminescence (PL), and cathodoluminescence (CL) spectroscopy were utilized to characterize the synthesized phosphors. The Mn2+-activated Zn2GeO4 phosphors exhibit narrow emission band at 532 nm under the excitation of ultraviolet light, which due to the 4T1(4G)-6A1(6S) transition of Mn2+ ions. Also it is observed that there exists energy transfer between the Zn2GeO4 host lattice and the activator (Mn2+). Under excitation of low-voltage electron beams, Zn2GeO4:Mn2+ shows strong green emission band dominating at 535 nm, corresponding to the 4T1(4G)-6A1(6S) emission of Mn2+ ions. The emission intensity and chromaticity coordinates of Zn2GeO4:Mn2+ as a function of accelerating voltage and the filament current were also investigated.

  17. Advanced phosphors

    DOEpatents

    Xiang, Xiao-Dong; Sun, Xiaodong; Schultz, Peter G.

    2000-01-01

    This invention relates to new phosphor materials and to combinatorial methods of synthesizing and detecting the same. In addition, methods of using phosphors to generate luminescence are also disclosed.

  18. Preparation and Characterization of UV Emitting Fluoride Phosphors for Phototherapy Lamps

    NASA Astrophysics Data System (ADS)

    Belsare, P. D.; Moharil, S. V.; Joshi, C. P.; Omanwar, S. K.

    2011-10-01

    The use of ultraviolet radiation for the treatment of various skin diseases is well known for long time. Phototherapy employs ultraviolet-blue radiation to cure skin diseases. The basis of phototherapy is believed to be the direct interaction of light of certain frequencies with tissue to cause a change in immune response. Currently dermatologists use UV lamps having specific emissions in UV region for treating various skin diseases. The treatment of skin diseases using artificial sources of UV radiation is now well established and more than 50 types of skin diseases are treated by phototherapy. This is an effective treatment for many skin disorders, such as psoriasis, vitiligo, ofujis disease, morphea , scleroderma, cutaneous T-cell lymphoma, lupus erythematosus, hyperbilirubinemia commonly known as infant jaundice, acne vulgaris, This paper reports photoluminescence properties of UV emitting fluoride phosphors prepared by wet chemical method. Emission characteristics of these phosphors are found similar to those of commercial UV lamp phosphors with comparable intensities. The usefulness of UV emitting fluoride phosphor is discussed in the paper.

  19. Thermoluminescence characterization of Dy(3+) -activated Mg₅ (BO₃ )₃ F low Z(eff) phosphor.

    PubMed

    Wani, Javaid A; Dhoble, N S; Dhoble, S J

    2013-01-01

    Thermoluminescence characteristics of Dy(3+) -activated Mg₅ (BO₃ )₃ F low Z(eff) phosphor are described. The Mg₅ (BO₃ )₃ F phosphor doped with Dy(3+) as activator was prepared by the modified solid-state reaction. Formation of the compound was confirmed by use of X-ray powder diffraction. The X-ray powder diffraction pattern of the as-prepared compound shows a good match with the available JCPDS data. The γ-irradiated Mg₅ (BO₃ )₃ F:Dy(3+) phosphor shows a simple glow curve peaking at about 148°C indicating that only one type of trap is being activated within a particular temperature range. The kinetic parameters, including activation energy and frequency factor were determined using Chen's method. The activation energy and frequency factors were 0.75 eV and 4.508 × 10(9) /s respectively. The Z(eff) ofMg₅ (BO₃ )₃ F:Dy(3+) phosphor was 9.84. PMID:23055350

  20. Characterization and endurance study of aluminate/silicate/garnet/nitride phosphors for high-performance SSL

    NASA Astrophysics Data System (ADS)

    Trivellin, Nicola; Meneghini, Matteo; Dal Lago, Matteo; Barbisan, Diego; Ferretti, Marco; Meneghesso, Gaudenzio; Zanoni, Enrico

    2013-03-01

    With this work we report on the performance and degradation mechanism of commercially available remote phosphors (RP) for SSL. Thermal analysis indicates that phosphors can reach temperatures above 60°C during operation at an ambient temperature of 25°C when subjected to an optical power of 346 mW/cm2. We also demonstrate that temperature is a strong driving force for the degradation. Results indicate a gradual reduction in luminous flux output and a decrease of correlated color temperature as a consequence of stress. We demonstrate that the degradation rate is strongly correlated with stress temperature with an activation energy of 1.36 eV for a TTF of 70%.

  1. Structural, electrical and optical characterization of high brightness phosphor-free white light emitting diodes

    NASA Astrophysics Data System (ADS)

    Omiya, Hiromasa

    Much interest currently exists in GaN and related materials for applications such as light-emitting devices operating in the amber to ultraviolet range. Solid-state lighting (SSL) using these materials is widely being investigated worldwide, especially due to their high-energy efficiency and its impact on environmental issues. A new approach for solid-state lighting uses phosphor-free white light emitting diodes (LEDs) that consist of blue, green, and red quantum wells (QW), all in a single device. This approach leads to improved color rendering, and directionality, compared to the conventional white LEDs that use yellow phosphor on blue or ultraviolet emitters. Improving the brightness of these phosphor-free white LEDs should enhance and accelerate the development of SSL technology. The main objective of the research reported in this dissertation is to provide a comprehensive understanding of the nature of the multiple quantum wells used in phosphor-free white LEDs. This dissertation starts with an introduction to lighting history, the fundamental concepts of nitride semiconductors, and the evolution of LED technology. Two important challenges in LED technology today are metal-semiconductor contacts and internal piezoelectric fields present in quantum well structures. Thus, the main portion of this dissertation consists of three parts dealing with metal-semiconductor interfaces, single quantum well structures, and multiple quantum well devices. Gold-nickel alloys are widely used as contacts to the p-region of LEDs. We have performed a detailed study for its evolution under standard annealing steps. The atomic arrangement of gold at its interface with GaN gives a clear explanation for the improved ohmic contact performance. We next focus on the nature of InGaN QWs. The dynamic response of the QWs was studied with electron holography and time-resolved cathodoluminescence. Establishing the correlation between energy band structure and the light emission spectra

  2. Thermoluminescent phosphor

    DOEpatents

    Lasky, Jerome B.; Moran, Paul R.

    1978-01-01

    A thermoluminescent phosphor comprising LiF doped with boron and magnesium is produced by diffusion of boron into a conventional LiF phosphor doped with magnesium. Where the boron dopant is made to penetrate only the outer layer of the phosphor, it can be used to detect shallowly penetrating radiation such as tritium beta rays in the presence of a background of more penetrating radiation.

  3. Phosphor powders elaborated by spray-pyrolysis: Characterizations and possible applications

    NASA Astrophysics Data System (ADS)

    Joffin, N.; Caillier, B.; Garcia, A.; Guillot, P.; Galy, J.; Fernandes, A.; Mauricot, R.; Dexpert-Ghys, J.

    2006-05-01

    Several well-known phosphors compositions based on rare earth orthoborates, with the general formula LnBO 3 with Ln = [Y 0.95- yGd yEu 0.05] or [Y 0.95- yGd yTb 0.05], and the cubic oxide (Y 0.96Eu 0.04) 2O 3 have been synthesized by spray-pyrolysis (SP) and additional thermal treatments. Samples with the unique hexagonal YBO 3 type phase have been obtained. The particles are spherical, the average diameter is around 2 μm, with a relatively narrow spreading. The borate spheres are not dense: porosities are observed, but do not exhibit the core-shell aspect observed for Y 2O 3:Eu 3+ spheres. The emission spectra, the relative intensities, and the transient characteristics of phosphors under VUV excitation by a pure Xe gas discharge have been measured in a specially developed experimental set-up. The integrated Eu 3+ emission intensities are at least 50% higher for SP yttrium borates than for SP yttrium oxide; the decay times τ10 are 13 ± 1 msec and 4.6 ± 0.4 msec, respectively. Up to 80% efficiency of a commercial green phosphor (Zn 2SiO 4:Mn 2+), and τ10 = 15 ± 1 msec were easily achieved in spray pyrolysed Tb 3+ yttrium borates. The Gd/Y substitution and the annealing temperature have a very weak effect on the europium and the terbium luminescence efficiencies and decay times.

  4. Retention of phosphorous ions on natural and engineered waste pumice: Characterization, equilibrium, competing ions, regeneration, kinetic, equilibrium and thermodynamic study

    NASA Astrophysics Data System (ADS)

    Karimaian, Kamal Aldin; Amrane, Abdeltif; Kazemian, Hossein; Panahi, Reza; Zarrabi, Mansur

    2013-11-01

    Natural and Mg2+ modified pumice were used for the removal of phosphorous. The adsorbents were characterized using XRF, XRD, SEM and FTIR instrumental techniques. In the optimal conditions, namely at equilibrium time (30 min), for a phosphorus concentration of 15 mg/L and pH 6, 69 and 97% phosphorus removals were achieved using 10 g/L of natural and modified pumice adsorbents, respectively. Maximum adsorption capacities were 11.88 and 17.71 mg/g by natural and modified pumice, respectively. Pseudo-second order kinetic model was the most relevant to describe the kinetic of phosphorus adsorption. External mass transfer coefficient decreased for increasing phosphorous concentration and film diffusion was found to be the rate-controlling step. Only a very low dissolution of the adsorbent was observed, leading to a low increase in conductivity and turbidity. Removal efficiency decreased for increasing ionic strength. It also decreased in the presence of competing ions; however modified pumice remained effective, since 67% of phosphorus was removed, versus only 17% for the natural pumice. The efficiency of the modified pumice was confirmed during the regeneration tests, since 96% regeneration yield was obtained after 510 min experiment, while only 22% was observed for the raw pumice.

  5. Fiber optic microprobes with rare-earth-based phosphor tips for proton beam characterization

    NASA Astrophysics Data System (ADS)

    Darafsheh, Arash; Kassaee, Alireza; Taleei, Reza; Dolney, Derek; Finlay, Jarod C.

    2016-03-01

    We investigated the feasibility of using fiber optics probes with rare-earth-based phosphor tips for proton beam radiation dosimetry. We designed and fabricated a fiber probe with submillimeter resolution based on TbF3 phosphors and evaluated its performance for measurement of proton beams including profiles and range. The fiber optic probe, embedded in tissue-mimicking plastics, was irradiated with a clinical proton beam and the luminescence spectroscopy was performed by a CCD-coupled spectrograph to analyze the emission spectra of the fiber tip. By using a linear fitting algorithm we extracted the contribution of the ionoluminescence signal to obtain the percentage depth dose in phantoms and compared that with measurements performed with a standard ion chamber. We observed a quenching effect in the spread out Bragg peak region, manifested as an under-responding of the signal due to the high linear energy transfer of the beam. However, the beam profiles measurements were not affected by the quenching effect indicating that the fiber probes can be used for high-resolution measurements of proton beams profile.

  6. Synthesis, characterization, photoluminescence and EPR investigations of Mn doped MgAl 2O 4 phosphors

    NASA Astrophysics Data System (ADS)

    Singh, Vijay; Chakradhar, R. P. S.; Rao, J. L.; Kim, Dong-Kuk

    2007-07-01

    MgAl 2O 4:Mn phosphors have been prepared at 500 °C by combustion route. Powder X-ray diffraction (XRD) indicated the presence of mono-MgAl 2O 4 phase. Scanning electron microscopy showed that the powder particle crystallites are mostly angular. Fourier transform infrared spectroscopy confirmed the presence of AlO 6 group which makes up the MgAl 2O 4 spinel. Photoluminescence studies showed green/red emission indicating that two independent luminescence channels in this phosphor. The green emission at 518 nm is due to 4T1 → 6A1 transition of Mn 2+ ions. The emission at 650 nm is due to the charge-transfer deexcitation associated with the Mn ion. EPR spectrum exhibits allowed and forbidden hyperfine structure at g=2.003. The g≈2.00 is due to Mn 2+ ion in an environment close to tetrahedral symmetry. It is observed that N and χ increase with decrease of temperature obeying the Boltzmann law. The variation of zero-field splitting parameter ( D) with temperature is evaluated and discussed.

  7. Fourier transform infrared characterization of the acidic phosphoric extractant system containing lanthanide

    NASA Astrophysics Data System (ADS)

    Shen, Y.-H.; Yao, S.-K.; Wang, D.-J.; Zhou, Weijin; Li, Ying Xue; Peng, Q.; Wu, JinGuang; Xu, Guang-Xian

    1994-01-01

    The aggregation states and FTIR spectra of the extractive organic phases of saponified HDEHP [di(2-ethylhexyl) phosphoric acid] (1). DMHPA [di(1-methylheptyl) phosphoric acid] (2) and (HDEHP + DMHPA) (3) containing lanthanides were studied, respectively. Transparent solution formed in system (1) while transparent gel formed in system (2) when the loading of lanthanides was more than 50%. The aggregation state of system (3) depends on the molar ratio of HDEHP:DMHPA and the loading percentage of lanthanide. From their FTIR spectra, it can be seen that the P equals O band of gel split into 1164, 1199, and 1232 cm-1, and the P-O-C band split into 1015, 1076, and 1083 cm-1 as well. The results suggested that the aggregation state of lanthanide complex changes considerably in the three systems, and multiple coordination states of p equals o with lanthanide result in the band split. Multiple interactions between P equals O, P-O-C and lanthanide ions form 3-D network in the gel.

  8. Blue light emitting thiogallate phosphor

    DOEpatents

    Dye, Robert C.; Smith, David C.; King, Christopher N.; Tuenge, Richard T.

    1998-01-01

    A crystalline blue emitting thiogallate phosphor of the formula RGa.sub.2 S.sub.4 :Ce.sub.x where R is selected from the group consisting of calcium, strontium, barium and zinc, and x is from about 1 to 10 atomic percent, the phosphor characterized as having a crystalline microstructure on the size order of from about 100 .ANG. to about 10,000 .ANG. is provided together with a process of preparing a crystalline blue emitting thiogallate phosphor by depositing on a substrate by CVD and resultant thin film electroluminescent devices including a layer of such deposited phosphor on an ordinary glass substrate.

  9. Characterizing LEDs for general illumination applications: mixed-color and phosphor-based white sources

    NASA Astrophysics Data System (ADS)

    Narendran, Nadarajah; Maliyagoda, Nishantha; Deng, Lei; Pysar, Richard M.

    2001-12-01

    The rapid development of high-brightness light emitting diodes (LEDs) has made this technology a potential candidate for architectural lighting applications. There are two distinct approaches for creating white light. The first is combining blue LEDs with a phosphor and the second is mixing monochromatic LEDs in appropriate proportions. This manuscript presents some of the critical issues involved in creating a good quality, stable white light source using the color mixture approach for LEDs. Some sample calculations for mixing different colored LEDs to obtain specific color appearance (CCT) and color rendering properties (CRI) are shown in this paper. Calculations show that the CRI values of mixed-color white LEDs can be changed significantly by shifting the wavelengths of the LEDs by a small amount. It is also shown that small amplitude and wavelength shifts can cause perceivable color differences in the mixed-color white LEDs. Therefore, circuits must be properly designed to power these types of white light sources so that they are acceptable for architectural lighting applications. Because the light output variation as a function of time at different drive currents was not readily available, an experiment was conducted to quantify the light output change as a function of time for red, green, blue and white 5-mm LEDs, at fiber different constant current values (20,30,40,50 and 50 mA). The light output of the different colored LEDs depreciated at different rates. The depreciation rates increased in the following order: red, green, blue, and white. Furthermore, the light output depreciation increased with increasing drive current. The red LEDs has the least amount of light output depreciation rate variation as function of drive current, green and blue LEDs ranked after that, and white LEDs had the most variation for the same drive current variation. A group of twelve new high-powered phosphor-based white LEDs were tested at their rated current, (which is much

  10. Synthesis and characterization of novel K2La2-xEuxTi3O10 phosphor for blue chip white LEDs

    NASA Astrophysics Data System (ADS)

    Grandhe, Bhaskar Kumar; Bandi, Vengala Rao; Jayasimhadri, M.; Jang, Kiwan; Lee, Ho-Sueb; Shin, Dong-Soo; Yi, Soung-Soo; Jeong, Jung-Hyun

    2013-05-01

    Eu3+ doped K2La2Ti3O10 (KLT) phosphors were prepared by means of conventional solid state reaction method. It has exhibited an intense excitation band at around 466 nm, which matches well to the popular emission line from a GaN based blue light-emitting diode (LED) chip. Using this as an excitation wavelength the Eu3+ doped KLT phosphors yielded two strong orange-red emission bands at 595 nm (5D0→7F1) and 616 nm (5D0→7F2) respectively. The obtained results suggest that Eu3+doped KLT phosphors are useful for blue chip white LEDs. Besides we have studied its dielectric properties along with the other significant characterizations like XRD, SEM and Tg-DTA.

  11. Characterization of noise sources for two generations of computed radiography systems using powder and crystalline photostimulable phosphors.

    PubMed

    Mackenzie, Alistair; Honey, Ian D

    2007-08-01

    The performances of two generations of computed radiography (CR) were tested and compared in terms of resolution and noise characteristics. The main aim was to characterize and quantify the noise sources in the images. The systems tested were (1) Agfa CR 25.0, a flying spot reader with powder phosphor image plates (MD 40.0); and (2) the Agfa DX-S, a line-scanning CR reader with needle crystal phosphor image plates (HD 5.0). For both systems, the standard metrics of presampled modulation transfer function (MTF), normalized noise power spectra (NNPS) and detective quantum efficiency (DQE) were measured using standard radiation quality RQA5 as defined by the International Electrotechnical Commission. The various noise sources contributing to the NNPS were separated by using knowledge of their relationship with air kerma, MTF, absorption efficiency and antialiasing filters. The DX-S MTF was superior compared with the CR 25.0. The maximum difference in MTF between the DX-S scan and CR 25.0 subscan directions was 0.13 at 1.3 mm(-1). For a nominal detector air kerma of 4 microGy, the peak DQE of the DX-S was 43 (+/-3)%, which was over double that of the CR 25.0 of 18 (+/-2)%. The additive electronic noise was negligible on the CR 25.0 but calculated to be constant 3.4 x 10(-7) (+/-0.4 x 10(-7)) mm2 at 3.9 microGy on the DX-S. The DX-S has improved image quality compared with a traditional flying spot reader. The separation of the noise sources indicates that the improvements in DQE of the DX-S are due not only to the higher quantum, efficiency and MTF, but also the lower structure, secondary quantum, and excess noise. PMID:17879798

  12. Characterization of noise sources for two generations of computed radiography systems using powder and crystalline photostimulable phosphors

    SciTech Connect

    Mackenzie, Alistair; Honey, Ian D.

    2007-08-15

    The performances of two generations of computed radiography (CR) were tested and compared in terms of resolution and noise characteristics. The main aim was to characterize and quantify the noise sources in the images. The systems tested were (1) Agfa CR 25.0, a flying spot reader with powder phosphor image plates (MD 40.0); and (2) the Agfa DX-S, a line-scanning CR reader with needle crystal phosphor image plates (HD 5.0). For both systems, the standard metrics of presampled modulation transfer function (MTF), normalized noise power spectra (NNPS) and detective quantum efficiency (DQE) were measured using standard radiation quality RQA5 as defined by the International Electrotechnical Commission. The various noise sources contributing to the NNPS were separated by using knowledge of their relationship with air kerma, MTF, absorption efficiency and antialiasing filters. The DX-S MTF was superior compared with the CR 25.0. The maximum difference in MTF between the DX-S scan and CR 25.0 subscan directions was 0.13 at 1.3 mm{sup -1}. For a nominal detector air kerma of 4 {mu}Gy, the peak DQE of the DX-S was 43({+-}3)%, which was over double that of the CR 25.0 of 18({+-}2)%. The additive electronic noise was negligible on the CR 25.0 but calculated to be constant 3.4x10{sup -7} ({+-}0.4x10{sup -7}) mm{sup 2} at 3.9 {mu}Gy on the DX-S. The DX-S has improved image quality compared with a traditional flying spot reader. The separation of the noise sources indicates that the improvements in DQE of the DX-S are due not only to the higher quantum, efficiency and MTF, but also the lower structure, secondary quantum, and excess noise.

  13. Synthesis, characterization, thermoluminescence and optical studies of Eu3+ doped Y2SiO5 phosphor

    NASA Astrophysics Data System (ADS)

    Parganiha, Yogita; Kaur, Jagjeet; Dubey, Vikas; Chandrakar, Deepika

    2015-01-01

    The present paper reports thermoluminescence (TL) glow curves and photoluminescence (PL) studies of europium doped yttrium silicate (Y2SiO5:Eu3+). The samples were prepared by the modified Solid state method which is the most suited method for large scale production. Starting material used for sample preparation was Y2O3, SiO2 and Eu2O3 with variable concentration of europium. A prepared sample was characterized by XRD (X-ray diffraction) and crystallite size found 20-50 nm in size. The PL excitation spectra was found at 265 and 395 nm while the emission spectra was found at 580, 588, 595, 598, 612, 615, 623 and 626 nm, the emission peak at 612 nm was most intense peak for all Eu3+ concentration. The effect of Eu3+ concentration on PL intensity was studied and found that intensity increases with increasing concentration up to 2.5 mol% of Eu3+. Commission Internationale de l'Eclairage co-ordinate (CIE) of this phosphor is (0.65, 0.31) in the red region. TL glow curves were recorded for different doses of UV exposure at a heating rate of 6.7 °C s-1. The kinetic parameters as activation energy 'E', the order of kinetics 'b', and the frequency factor 's' of Y2SiO5:Eu3+ have been calculated by using peak shape method. The sample shows general order kinetics. The effect of Eu3+ concentration on TL intensity was also studied and found that the intensity increases linearly up to 1 mol% and then decreases with increasing concentration of Eu3+. The present phosphor acts as a single host for red emission display devices and light emitting diode (LED) as well as may be used for thermoluminescence dosimetric material under UV exposure.

  14. Physical characterization of magmatic liquids

    SciTech Connect

    Manghnani, M.H.

    1991-01-01

    Long-range goals of this research project are: (1) Characterization of seismic velocity and attenuation (V{sub p}, V{sub S}, Q{sub p}{sup {minus}1}, Q{sup S}{sup {minus}1}) and electrical properties of selected Hawaiian and related rocks under appropriate controlled environments of pressure, temperature and volatile/fluid content; and, (2) Characterization of the elastic, viscoelastic and thermodynamic properties (V{sub p}, V{sub S}, Q{sub P}{sup {minus}1}, Q{sub S}{sup {minus}1}, viscosity and compressibility) of molten basalts, picrites and komatites, and related silicate melts to {approximately} 1600{degrees}C using the ultrasonic interferometry method. In addition, the pressure dependences of V{sub p},V{sub S} and bulk modulus will be determined using the Brillouin scattering and diamond- anvil cell techniques.

  15. Radiological, chemical and morphological characterizations of phosphate rock and phosphogypsum from phosphoric acid factories in SW Spain.

    PubMed

    Rentería-Villalobos, Marusia; Vioque, Ignacio; Mantero, Juan; Manjón, Guillermo

    2010-09-15

    In this work, radiological, chemical, and also morphological characterization was performed in phosphate rock and phosphogypsum samples, in order to understand the behavior of toxic elements. Characterization was carried out using X-ray diffraction (XRD), X-ray fluorescence (XRF), gamma spectrometry and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). Our results show that the phosphate rock was mainly composed of fluorapatite, calcite, perovskite, quartz, magnetite, pyrite and kaolinite, whereas phosphogypsum only exhibited dihydrated calcium sulfate. The activity concentration of U-series radioisotopes in phosphate rock was around 1640 Bq/kg. (226)Ra and (210)Pb tend to be distributed into phosphogypsum by up to 80%, whereas the fraction of U-isotopes is 10%. The most abundant trace elements in phosphate rock were Sr, Cr, V, Zn, Y, Ni and Ba. Some elements, such as Ba, Cd, Cu, La, Pb, Se, Sr, Th and Y, were enriched in the phosphogypsum. This enrichment may be attributed to an additional input associated to the sulfuric acid used for the phosphoric acid production. Furthermore, results from SEM-EDX demonstrated that toxic elements are not distributed homogeneously into phosphogypsum. Most of these elements are concentrated in particles <20 microm of high porosity, and could be easily mobilized by leaching and/or erosion. PMID:20537794

  16. The physics of computed radiography: Measurements of pulse height spectra of photostimulable phosphor screens using prompt luminescence

    SciTech Connect

    Watt, Kristina N.; Yan, Kuo; DeCrescenzo, Giovanni; Rowlands, J. A.

    2005-12-15

    Computed radiography (CR) is a digital technology that employs reusable photostimulable phosphor (PSP) imaging plates (IP) to acquire radiographic images. In CR, the x-ray attenuation pattern of the imaged object is temporarily stored as a latent charge image within the PSP. The latent image is optically readout as photostimulated luminescence (PSL) when the phosphor is subsequently stimulated using a scanning laser. The multiple stages necessary to create a CR image make it difficult to investigate either experimentally or theoretically. In order to examine the performance of the CR system at a fundamental level separate measurements of the processes involved are desirable. Here pulse height spectroscopy is used to study the prompt violet light emission or prompt luminescence (PL) from commercial PSP screens. Since the mechanism by which light escapes from the phosphor is identical for PL and PSL, observations and conclusions based on the pulse height spectra (PHS) of PL are relevant to the understanding of the behavior of the PSL light emission that outputs the radiographic image in CR. The PL PHS of screens of different thickness and optical properties were measured and compared with the PHS of conventional phosphors. A new method for calibration of the PHS in terms of the absolute number of optical photons per x-ray is introduced and compared to previously established methods.

  17. Eu3+-activated SrMoO4 phosphors for white LEDs applications: Synthesis and structural characterization

    NASA Astrophysics Data System (ADS)

    Shivakumara, C.; Saraf, Rohit

    2015-04-01

    We report the synthesis of Eu3+-activated SrMoO4 phosphors by the facile nitrate-citrate gel combustion method. Powder XRD and Rietveld refinement data confirmed that these phosphors have a monophasic scheelite-type tetragonal structure with space group I41/a (No. 88). FESEM micrographs indicate the agglomerated spherical particles. FTIR spectra showed four stretching and bending vibrational modes (2Au and 2Eu). UV-Visible absorption spectroscopy illustrated that the optical band gap energy (Eg) values increase with increase in Eu3+ concentration. The host SrMoO4 phosphor exhibited an intense blue emission under UV excitation (368 nm). The Eu3+-activated SrMoO4 phosphors revealed characteristic luminescence due to Eu3+ ion corresponding to 5D1 → 7FJ (J = 1, 2) and 5D0 → 7FJ (J = 1, 2, 3, 4) transitions upon 465 nm excitation. The electric dipole transition located at 615 nm (5D0 → 7F2) was stronger than the magnetic dipole transition located at 592 nm (5D0 → 7F1). Intensity parameters (Ω2, Ω4) and radiative properties such as transition probabilities (AT), radiative lifetime (τrad) and branching ratio (β) of Eu3+-activated SrMoO4 phosphors were calculated using the Judd-Ofelt theory. Based on the CIE chromaticity diagram, these phosphors can be promising materials for the development of blue and orange-red component in white LEDs.

  18. Phosphoric acid

    Integrated Risk Information System (IRIS)

    Phosphoric acid ; CASRN 7664 - 38 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  19. Characterizing scientific production and consumption in Physics

    PubMed Central

    Zhang, Qian; Perra, Nicola; Gonçalves, Bruno; Ciulla, Fabio; Vespignani, Alessandro

    2013-01-01

    We analyze the entire publication database of the American Physical Society generating longitudinal (50 years) citation networks geolocalized at the level of single urban areas. We define the knowledge diffusion proxy, and scientific production ranking algorithms to capture the spatio-temporal dynamics of Physics knowledge worldwide. By using the knowledge diffusion proxy we identify the key cities in the production and consumption of knowledge in Physics as a function of time. The results from the scientific production ranking algorithm allow us to characterize the top cities for scholarly research in Physics. Although we focus on a single dataset concerning a specific field, the methodology presented here opens the path to comparative studies of the dynamics of knowledge across disciplines and research areas. PMID:23571320

  20. Characterizing scientific production and consumption in Physics

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Perra, Nicola; Gonçalves, Bruno; Ciulla, Fabio; Vespignani, Alessandro

    2013-04-01

    We analyze the entire publication database of the American Physical Society generating longitudinal (50 years) citation networks geolocalized at the level of single urban areas. We define the knowledge diffusion proxy, and scientific production ranking algorithms to capture the spatio-temporal dynamics of Physics knowledge worldwide. By using the knowledge diffusion proxy we identify the key cities in the production and consumption of knowledge in Physics as a function of time. The results from the scientific production ranking algorithm allow us to characterize the top cities for scholarly research in Physics. Although we focus on a single dataset concerning a specific field, the methodology presented here opens the path to comparative studies of the dynamics of knowledge across disciplines and research areas.

  1. Optical characterization of YAl3(BO3)4:Dy3+-Tm3+ phosphors under near UV excitation

    NASA Astrophysics Data System (ADS)

    Lokeswara Reddy, G. V.; Rama Moorthy, L.; Packiyaraj, P.; Jamalaiah, B. C.

    2013-10-01

    Dy3+ and Tm3+ co-doped YAl3(BO3)4 (YAB) phosphors were prepared by solid-state reaction method at 1200 °C/3 h. The average crystallite size was determined as 52.09 nm from the X-ray diffraction measurements. Upon 352 and 359 nm near ultra violet excitation, the YAB:Dy3+-Tm3+ phosphors exhibit Dy3+:4F9/2 → 6HJ (J = 15/2, 13/2, 11/2) and Tm3+:1D2 → 3F4 transitions with different luminescence intensity. The photoluminescence emission and decay measurements revealed the energy transfer from Dy3+ to Tm3+ ions under 359 nm excitation only. The energy transfer between Dy3+ and Tm3+ takes place in Dy3+-Tm3+ clusters through exchange interaction mechanism. The Commission International de I'Eclairage chromaticity coordinates of YAB:Tm3+ phosphor (λex = 359 nm) were found very close to the European Broadcasting Union and National Television Standard Committee illuminants. The emission color of the studied phosphors could be tuned from blue-to-white as a function of excitation wavelength. The YAB:Dy3+-Tm3+ phosphors can be used as potential candidates in display technology.

  2. Spectroscopic characterizations of Er doped LaPO4 submicron phosphors prepared by homogeneous precipitation method

    NASA Astrophysics Data System (ADS)

    Saltmarsh, N.; Kumar, G. A.; Kailasnath, M.; Shenoy, Vittal; Santhosh, C.; Sardar, D. K.

    2016-03-01

    Hexagonal shaped LaPO4 submicron particles doped with various concentrations of Er were successfully prepared by homogenous precipitation method using metal nitrates and ammonium phosphate. Particles of approximate particle size 125 nm and size distribution of 85 nm are obtained with good crystallinity. After heat treatment at 1200 °C for 2 h, the particles are characterized for their various optical properties such as absorption, emission, fluorescence decay and optical band gap. Optical absorption and emission data are numerically analyzed with the help of Judd-Ofelt model to evaluate various radiative spectral properties such as radiative decay rates, radiative quantum yield, emission cross-section and fluorescence branching ratios of various emission transitions. Though the radiative quantum yield of 1554 nm emission approaches the theoretical limit of 100%, the experimentally measured quantum yield is only 11% at 12 W/cm2 at 980 nm excitation power density in 2% Er doped LaPO4.

  3. Thermoluminescence characterization of LiMgF3:DyF3 phosphors exposed to beta radiation

    NASA Astrophysics Data System (ADS)

    Bernal, R.; Alday-Samaniego, K. R.; Furetta, C.; Cruz-Zaragoza, E.; Kitis, G.; Brown, F.; Cruz-v&Ázquez, C.

    LiMgF3:DyF3 phosphors were obtained as polycrystalline solids from the melting of component salts, with two DyF3 concentrations, 2.02% mol and 4.04% mol. In order to guarantee the homogeneity of the composition, the samples were crushed and the resulting powder was pressed to form pellet-shaped phosphors, some of which were sintered at 700 °C for 5 h, under atmospheric air. Thermoluminescence measurements of beta irradiated samples show that these phosphors exhibit adequate properties to be considered for development of thermoluminescence dosimeters. Integrated thermoluminescence as a function of dose displays a linear dependence with dose for doses below 20.0 Gy.

  4. Preparation, characterization and catalytic sodium borohydride hydrolysis of nanostructured cobalt-phosphorous catalysts

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Qi, Kezhen; Wu, Shiwei; Cao, Zhongqiu; Zhang, Ke; Lu, Yunshu; Liu, Hongxin

    2015-06-01

    In this paper, we report on the preparation, characterization and catalytic NaBH4 hydrolysis of nanostructured Co-P catalysts prepared using electroless plating method on the Cu sheet. Co-P catalysts composed of nanoplatelets, nanospheres and nanoflowers are successfully obtained by tuning the NaH2PO2 concentration. The as-prepared Co-P sample with hierarchical flower-like shape shows significantly enhanced catalytic activity during hydrolytic dehydrogenation of NaBH4, affording hydrogen release rate of 1647.9 mL min-1 g-1 at 30 °C and an activation energy of 47.0 kJ mol-1. This enhanced activity is due to their novel nanoflower architectures made up of nanoplatelets or the high surface roughness, providing many defects of angle, step, or edge and so on, to form more active sites on the catalyst surface. Furthermore, the hydrogen generation rate decreases gradually after 11 cycles, about 61% of the initial hydrogen generation rate. The study reveals the reason may be the decrease in the amount of P that provides active metallic Co sites on the catalyst surface.

  5. Synthesis and Characterization of SiO2@Y2MoO6:Eu3+ Core-Shell Structured Spherical Phosphors by Sol-Gel Process.

    PubMed

    Li, G Z; Liu, F H; Chu, Z S; Wu, D M; Yang, L B; Li, J L; Wang, M N; Wang, Z L

    2016-04-01

    SiO2@Y2MoO6:Eu3+ core-shell phosphors were prepared by the sol-gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO2@Y2MoO6:Eu3+ core-shell phosphors. The XRD results demonstrated that the Y2MoO6:Eu3+ layers on the SiO2 spheres crystallized after being annealed at 700 °C and the crystallinity increased with raising the annealing temperature. The obtained core-shell phosphors have spherical shape with narrow size distribution (average size ca. 640 nm), non-agglomeration, and smooth surface. The thickness of the Y2MoO6:Eu3+ shells on the SiO2 cores could be easily tailored by varying the number of deposition cycles (70 nm for four deposition cycles). The Eul+ shows a strong PL emission (dominated by 5D0-7F2 red emission at 614 nm) under the excitation of 347 nm UV light. The PL intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles. PMID:27451737

  6. Growth and characterization of Y 2O 3:Eu 3+ phosphor films by sol-gel process

    NASA Astrophysics Data System (ADS)

    Rao, Ravi P.

    1996-08-01

    Phosphor films play an important role in high resolution display devices, remote thermometry, gas sensors, etc. These films were grown by various methods. In the present paper, europium activated yttrium oxide (Y 2O 3:Eu) phosphor films were deposited from yttrium hydroxide gels by dip and dry and spin coating methods. XRD of the films, calcinated at 700 to 1000°C showed all the prominent lines of the yttria phase. From SEM studies, it was observed that these films were uniform and defect free. Luminescence intensity was comparable with that of Y 2O 3:Eu powder samples.

  7. Long-Term Cathodoluminescent Characterization of Thin-Film Oxide Phosphors in a Wide Range of Electron Excitation Densities

    SciTech Connect

    Bondar, V D; Felter, T E; Hunt, C E; Dubov, Y G; Chakhovskoy, A G

    2001-04-09

    Long-term processes of cathodoluminescence degradation of thin film phosphors Zn{sub 2}SiO{sub 4}:Ti and Zn{sub 2}GeO{sub 4}:Mn were investigated in a wide range of e-beam energies, current and power densities. The time dependencies describing decreasing of emission intensity have been found. At high-level densities of e-beam irradiation the specific behavior of long-term degradation processes was observed, which is characteristic with rapid degradation at initial stage and slow consequent decrease of intensity. The most probable mechanisms responsible for long-term processes of degradation in investigated phosphors are proposed.

  8. Long-Term Cathodoluminescent Characterization of Thin-Film Oxide Phosphors in a Wide Range of Electron Excitation Densities

    SciTech Connect

    Bondar, V D; Felter, T E; Hunt, C E; Dubov, Y G; Chakhovskoi, A G

    2001-05-06

    Long-term processes of cathodoluminescence degradation of thin film phosphors Zn{sub 2}SiO{sub 4}:Ti and Zn{sub 2}GeO{sub 4}:Mn were investigated in a wide range of e-beam energies, current and power densities. The time dependencies describing decreasing of emission intensity have been found. At high-level densities of e-beam irradiation the specific behavior of long-term degradation processes was observed, which is characteristic with rapid degradation at initial stage and slow consequent decrease of intensity. The most probable mechanisms responsible for long-term processes of degradation in investigated phosphors are proposed.

  9. Spectral and kinetic characterization of CaS:Pr 3+ phosphor synthesized through chemical co-precipitation route and post annealing process

    NASA Astrophysics Data System (ADS)

    Pitale, Shreyas S.; Sharma, Suchinder K.; Dubey, R. N.; Qureshi, M. S.; Malik, M. M.

    2010-01-01

    Synthesis of Pr 3+ doped CaS phosphor has been reported through chemical co-precipitation route and post annealing in the presence of NaCl, KCl and NH 4Cl flux. Good crystallinity and cubic CaS phase is achieved after post-precipitation calcinations of powder at 900 °C for 1 h duration. Pseudo-spherical morphostructural features of micron-size particles are observed for phosphor prepared via chemical route. Phosphor samples are also prepared via solid-state carbothermal reduction technique for comparative studies and exhibit dendrite like structures. Prominent excitation bands at 276, 320 nm are observed for the present phosphor samples. The emission spectra show a duo-band feature at 495 and 580 nm where a spectral overlap of host lattice emission due to intrinsic defects and characteristic spectral features of Pr ion due to 3P 0- 1H 4, 3P 1- 1H 5, 1D 2- 3H 4 and 3P 0- 3F 2 transitions can be observed. The carbothermal route synthesized CaS:Pr shows spectral features of Pr ion due to 3P 0- 1H 4 and 3P 0- 3F j transitions. Electron spin resonance investigations reveal the presence of unintentional Mn 2+ through a sextet signature. F + electron trapping center is detected having g = 2.0034. Thermoluminescence glow curves possess a broad duo-band feature between room temperature -100 °C and >125 °C under host UV irradiation. Kinetic characterization using glow curve deconvolution reveals quasicontinuous distribution of traps having energy between 0.56 and 1.15 eV and frequency factors between 10 7 and 10 11/sec.

  10. Characterization of phosphor materials for use in plasma display panel by time-resolved vacuum-ultraviolet laser spectrometry.

    PubMed

    Hirakawa, Y; Nakamura, K; Imasaka, T

    2001-11-15

    Phosphor materials that were manufactured for use in a plasma display panel (PDP) were investigated by employing a newly designed time-resolved vacuum-ultraviolet (VUV) spectrometer, which consists of a pulsed VUV laser and a fast photodetector. The VUV spectrometer was used to collect quantum efficiency data as well as the rise and decay times for the PDP phosphor luminescence. Both the rise and decay times increased with decreasing excitation wavelength in the VUV region. This result can be explained by a change in the mechanisms of photoexcitation and luminescence, that is, from charge-transfer excitation to host-lattice excitation below 200 nm. The present instrument was also used for an evaluation of the phosphor materials (Ba(1 - x)MgAl10O17:Eu2+(x)) by changing the Eu2+ concentration. The obtained data suggest that the impurities and defects are located inside the host crystal. Thus, the VUV spectrometer constructed in this study has considerable potential for use in investigating the nature of PDP phosphor materials. PMID:11816576

  11. Characterizing production and consumption in Physics

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Ciulla, Fabio; Goncalves, Bruno; Perra, Nicola; Vespignani, Alessandro

    2013-03-01

    We analyze the entire database of publications in the American Physical Society and generate longitudinal (50 years) citation networks at two different geographical levels. We define the knowledge diffusion proxy and Scientific Production Ranking algorithms to capture the complex nature of citation networks, and to provide a global view of spatial distributions of production and consumption of knowledge in Physics as well as its temporal evolution. Using the knowledge diffusion proxy we identify the key actors in producing and consuming knowledge in Physics as a function of time. The ranking results from the Scientific Production Ranking algorithm allow us to characterize the top countries/cities in the world for Physical sciences. Among all the results, we find that in 50 years major states and cities in US stably rank on the top and have been main knowledge producers, whereas the major European countries, Japan and Russia have greatly improved their their ranking since 1990. Interestingly, we notice that China and Spain as well as major cities in those countries have gradually become major knowledge consumers in the last two decades.

  12. 40 CFR 792.135 - Physical and chemical characterization studies.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 33 2013-07-01 2013-07-01 false Physical and chemical characterization... A Study § 792.135 Physical and chemical characterization studies. (a) All provisions of the GLPs shall apply to physical and chemical characterization studies designed to determine...

  13. 40 CFR 792.135 - Physical and chemical characterization studies.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 32 2011-07-01 2011-07-01 false Physical and chemical characterization... A Study § 792.135 Physical and chemical characterization studies. (a) All provisions of the GLPs shall apply to physical and chemical characterization studies designed to determine...

  14. 40 CFR 792.135 - Physical and chemical characterization studies.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 32 2014-07-01 2014-07-01 false Physical and chemical characterization... A Study § 792.135 Physical and chemical characterization studies. (a) All provisions of the GLPs shall apply to physical and chemical characterization studies designed to determine...

  15. 40 CFR 792.135 - Physical and chemical characterization studies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 31 2010-07-01 2010-07-01 true Physical and chemical characterization... A Study § 792.135 Physical and chemical characterization studies. (a) All provisions of the GLPs shall apply to physical and chemical characterization studies designed to determine...

  16. 40 CFR 792.135 - Physical and chemical characterization studies.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 33 2012-07-01 2012-07-01 false Physical and chemical characterization... A Study § 792.135 Physical and chemical characterization studies. (a) All provisions of the GLPs shall apply to physical and chemical characterization studies designed to determine...

  17. Synthesis and thermoluminescence characterizations of Sr2B5O9Cl:Dy3+ phosphor for TL dosimetry.

    PubMed

    Oza, Abha H; Dhoble, N S; Park, K; Dhoble, S J

    2015-09-01

    The photoluminescence (PL) and thermoluminescence (TL) displayed by Dy-activated strontium haloborate (Sr2 B5 O9 Cl) were studied. A modified solid-state reaction was employed for the preparation of the phosphor. Photoluminescence spectra showed blue (484 nm) and yellow (575 nm) emissions due to incorporation of Dy(3+) into host matrix. The Dy-doped (0.5 mol%) Sr2 B5 O9 Cl was studied after exposure to γ-irradiation and revealed a prominent glow curve at 261°C with a small hump around 143°C indicating that two types of traps were generated. The glow peak at the higher temperature side (261°C) was more stable than the lower temperature glow peak. The TL intensity was 1.17 times less than that of the standard CaSO4 :Dy thermoluminescence dosimetry (TLD) phosphor, the phosphor showed a linear dose-response curve for different γ-ray irradiation doses (0.002-1.25 Gy) and fading of 5-7% was observed for higher temperature peaks upon storage. Trapping parameters and their estimated error values have been calculated by Chen's peak shape method and by the initial rise method. Values of activation energies estimated by both these techniques were comparable. The slight difference in activation energy values calculated by Chen's peak shape method indicated the formation of two kinds of traps Furthermore, slight differences in frequency values are due to various escaping and retrapping probabilities. PMID:25428207

  18. Synthesis and properties of powder phosphor materials for field emission displays

    NASA Astrophysics Data System (ADS)

    Jiang, Yondong

    Field Emission Display (FED) is one of the most promising Flat Panel Display (FPD) technologies in the twenty-first century. Highly efficient phosphors with high resistance to current saturation, long service time and equal or better chromaticity than CRT phosphors are one of the keys for Field emission display (FED) technologies. The objectives of this project are to synthesize high quality red phosphor yttrium oxide (Y2O3:Eu 3+) and green phosphor strontium thiogallate (SrGa2S 4:Eu2+) and to characterize their physical properties. Y2O3:Eu3+ was prepared by a hydrolysis technique at low process temperature. Powders prepared by this method were spherical with uniform particle size distribution. The effects of dopant concentration, particle size and calcining temperature on luminous efficiency have been investigated. The optimum performance was found for a material prepared at 2 mol. % Eu doping and 2 hour firing of 1400°C. The effects of firing temperature on particle microstructure have been studied as well. SrGa2S4:Eu2+ was synthesized by an environmentally clean technique, in which gallium complex, europium complex, strontium sulfide and sulfur were used as raw materials and hydrogen sulfide was replaced by argon gas. A self-defining optimization method has been employed to optimize processing parameters. The effects of composition, firing temperature, firing time and annealing conditions on phosphor morphology and luminescent properties were studied. It was found that firing the phosphor at 900°C for 5 hours, and then ball-milling for 8 hours and annealing at 850°C for 5 hours gave the highest luminous efficiency. Although smaller thiogallate phosphors decreased the luminous efficiency, a significant improvement in aging performance was observed from the screens that were prepared from the smaller phosphors. Also the unstable thiogallate phosphors were coated with several oxides to improve their aging behavior. Luminous efficiency and aging performance were

  19. OMVPE Growth and Characterization of GaInP on GaAs Using Tertiary Butylphosphine for the Phosphorous Source

    NASA Astrophysics Data System (ADS)

    Takeda, Yoshikazu; Araki, Soichiro; Takemi, Masayoshi; Noda, Susumu; Sasaki, Akio

    1990-07-01

    GaInP layers were grown on GaAs substrates by organometallic vapor-phase epitaxy (OMVPE) at atmospheric pressure using trimethylgallium (TMGa), trimethylindium (TMIn) and much less toxic tertiary butylphosphine (TBP) as source gases. Fairly smooth surfaces were obtained at the growth temperature of 65O°C and at the V/III ratio of 78. The electrical and optical characteristics are comparable to those obtained by OMVPE using phosphine as the phosphorous source and far better than the previous results obtained by OMVPE with TBP. The undoped epitaxial layers showed n-type conductivity with electron concentrations of 2--3× 1017 cm-3.

  20. Synthesis, characterization and luminescence behavior of ZrO2:Eu3+, Dy3+ with variable concentration of Eu and Dy doped Phosphor

    NASA Astrophysics Data System (ADS)

    Kaur, Jagjeet; Parganiha, Yogita; Dubey, Vikas; Singh, Deepti; Chandrakar, Deepika

    2014-09-01

    The present paper reports thermoluminescence (TL) glow curves and photoluminescence (PL) studies of europium, dysprosium co-doped zirconia (ZrO2:Eu3+, Dy3+). The sample were prepared by the solid state method with variable concentration of Eu (0.5-2 mol%) and Dy (0.5-2 mol%); thereafter, the TL glow curves were recorded for different doses of UV exposure at a heating rate of 6.7 °C s-1. The kinetic parameters activation energy E, the order of kinetics b, and the frequency factor “s” of synthesized phosphors of ZrO2:Eu3+, Dy3+ have been calculated by using a peak shape method. The sample was characterized by XRD (X-ray diffraction), SEM (scanning electron microscope) and FTIR (Fourier transform infrared spectroscopy). Effect of Eu and Dy concentration of PL and TL studies are also interpreted. Here the photoluminescence excitation and emission spectra were found at 307 and 395 nm and 594, 612 and 627 nm range respectively. The present phosphor acts as a single host for red emission display devices as well as may be used for thermoluminescence dosimetric material under UV exposure. Commission Internationale de l'éclairage co-ordinate of this nanophosphor (0.32, 0.34) is closed to that of the ideal white light (0.33, 0.33). Correlated color temperature of the white light (5894 K) is within the range of vertical daylight.

  1. 40 CFR 160.135 - Physical and chemical characterization studies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Physical and chemical characterization... and chemical characterization studies. (a) All provisions of the GLP standards shall apply to physical and chemical characterization studies designed to determine stability, solubility, octanol...

  2. 40 CFR 160.135 - Physical and chemical characterization studies.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Physical and chemical characterization... and chemical characterization studies. (a) All provisions of the GLP standards shall apply to physical and chemical characterization studies designed to determine stability, solubility, octanol...

  3. 40 CFR 160.135 - Physical and chemical characterization studies.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Physical and chemical characterization... and chemical characterization studies. (a) All provisions of the GLP standards shall apply to physical and chemical characterization studies designed to determine stability, solubility, octanol...

  4. 40 CFR 160.135 - Physical and chemical characterization studies.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Physical and chemical characterization... and chemical characterization studies. (a) All provisions of the GLP standards shall apply to physical and chemical characterization studies designed to determine stability, solubility, octanol...

  5. 40 CFR 160.135 - Physical and chemical characterization studies.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Physical and chemical characterization... and chemical characterization studies. (a) All provisions of the GLP standards shall apply to physical and chemical characterization studies designed to determine stability, solubility, octanol...

  6. Characterization of the Source Physics Experiment Site

    NASA Astrophysics Data System (ADS)

    Sussman, A. J.; Schultz-Fellenz, E. S.; Broome, S. T.; Townsend, M.; Abbott, R. E.; Snelson, C. M.; Cogbill, A. H.; Conklin, G.; Mitra, G.; Sabbeth, L.

    2012-12-01

    Designed to improve long-range treaty monitoring capabilities, the Source Physics Experiments, conducted at the Nevada National Security Site, also provide an opportunity to advance near-field monitoring and field-based investigations of suspected underground test locations. In particular, features associated with underground testing can be evaluated using Source Physics Experiment activities as analogs, linking on-site inspections with remote sensing technologies. Following a calibration shot (SPE 1), SPE 2 (10/2011) and SPE 3 (07/2012) were performed in the same emplacement hole with 1.0 ton of explosives at 150 ft depth. Because one of the goals of the Source Physics Experiments is to determine damage effects on seismic wave propagation and improve modeling capabilities, a key component in the predictive component and ultimate validation of the models is a full understanding of the intervening geology between the source and instrumented bore holes. Ground-based LIDAR and fracture mapping, mechanical properties determined via laboratory testing of rock core, discontinuity analysis and optical microscopy of the core rocks were performed prior to and following each experiment. In addition, gravity and magnetic data were collected between SPE 2 and 3. The source region of the explosions was also characterized using cross-borehole seismic tomography and vertical seismic profiling utilizing two sets of two boreholes within 40 meters of ground zero. The two sets of boreholes are co-linear with the explosives hole in two directions. Results of the LIDAR collects from both SPE 2 and 3 indicate a permanent ground displacement of up to several centimeters aligning along the projected surface traces of two faults observed in the core and fractures mapped at the surface. Laboratory testing and optical work show a difference in the characteristics of the rocks below and above 40 feet and within the fault zones.The estimated near-surface densities from the gravity survey show

  7. Characterizing the epistemological development of physics majors

    NASA Astrophysics Data System (ADS)

    Gire, Elizabeth; Jones, Barbara; Price, Edward

    2009-06-01

    Students in introductory physics courses are likely to have views about physics that differ from those of experts. However, students who continue to study physics eventually become experts themselves. Presumably these students either possess or develop more expertlike views. To investigate this process, the views of introductory physics students majoring in physics are compared with the views of introductory physics students majoring in engineering. In addition, the views of physics majors are assessed at various stages of degree progress. The Colorado learning attitudes about science survey is used to evaluate students’ views about physics, and students’ overall survey scores and responses to individual survey items are analyzed. Beginning physics majors are significantly more expertlike than nonmajors in introductory physics courses, and this high level of sophistication is consistent for most of undergraduate study.

  8. Physical and Morphological Characterization of Templated Thermosets

    NASA Astrophysics Data System (ADS)

    Hermel-Davidock, Theresa J.

    2005-03-01

    It has been found that by the addition of low concentrations of an amphiphilic block copolymer to an epoxy resin, novel disordered morphologies can be formed and preserved through cure. It has also been found that the addition of small amounts of block copolymer can improve the fracture resistance significantly without sacrificing the high modulus and glass transition temperature of these thermoset materials. This report will focus on characterizing the influence of the block copolymer and casting solvent on the morphology achieved in the thermoset sample and the resulting physical properties. Templated thermoset samples exhibiting two different diblock copolymer morphologies, worm-like micelles and spherical micelles were investigated. The micro-deformation mechanisms of these templated thermosets were studied via an in-situ tensile deformation technique performed in a transmission electron microscope (TEM). The micro-deformation behaviors of these samples were found to correlate well with the macroscopic mechanical properties. The toughening effect obtained in the epoxy resin was attributed to the well-dispersed worm-like morphology and the weak interfacial adhesion between the micelles and the matrix.

  9. Physical characterization of fast rotator NEOs

    NASA Astrophysics Data System (ADS)

    Kikwaya Eluo, Jean-Baptiste; Hergenrother, Carl W.

    2015-08-01

    Understanding the physical characteristics of fast rotator NEOs (sub-km sizes with H > 22) is important for two reasons: to establish properties that can constraint models of their potential hazard, and to learn about the origin and the evolution of the solar system. Technically it is difficult to cover different ranges of wavelengths using one telescope with one instrument. Setting up a network of telescopes with different instruments observing simultaneously the same object will efficiently contribute to the characterization of NEOs.ART (Arizona Robotic Telescope) is a University of Arizona initiative whose goal is to use local 2-m size telescopes to provide near real-time observations of Target of Opportunity objects covering the visible and the near- infrared wavelengths. We plan to use three telescopes of the ART project to observe fast rotator NEOs: 1) VATT (Vatican Advanced Technology Telescope) at Mount Graham (longitude: -109.8719, latitude: 32.7016, elevation: 10469 feet) with VATT-4K optical imager for photometry to estimate colors, lightcurves to get the rotation rate, and estimate the phase angle function of NEOs, 2) Bok 2.3 m at Kitt Peak (longitude: -111.6004, latitude: 31.9629, elevation: 6795 feet) with BCSpec (Boller & Chivens Spectrograph) for visible spectroscopy, and 3) Kuiper 1.5-m at Mount Bigelow (longitude: -110.7345, latitude: 32.4165, elevation: 8235 feet) with a near-infrared instrument.We report here the preliminary results of several NEOs whose rotation rate, color, and type have been estimated using photometry with images recorded with VATT-4K. 2009 SQ104 has a rotation rate of 6.85+/- 0.03 h, 2014 AY28 has a rotation rate of 0.91 +/- 0.02 h, 2014 EC of 0.54 +/-0.04 h, 2014 FA44 of 3.45 +/- 0.05 h, 2014 KS40 of 1.11 +/- 0.06 h, 2011 PT of 0.17 +/- 0.05 h, 2014 SC324 of 0.36 +/- 0.43 h, 2014 WF201 of 1.00 +/- 0.03 h. Of these objects, 2014 HM2, 2014 FA, 2014 SB145, 2011 PT fall among X-type asteroids; 2014 KS, 2014 WF are likely to be

  10. Refined Characterization of Student Perspectives on Quantum Physics

    ERIC Educational Resources Information Center

    Baily, Charles; Finkelstein, Noah D.

    2010-01-01

    The perspectives of introductory classical physics students can often negatively influence how those students later interpret quantum phenomena when taking an introductory course in modern physics. A detailed exploration of student perspectives on the interpretation of quantum physics is needed, both to characterize student understanding of…

  11. Preparation and Characterization of Chromium(III)-Activated Yttrium Aluminum Borate: A New Thermographic Phosphor for Optical Sensing and Imaging at Ambient Temperatures

    PubMed Central

    2010-01-01

    A new thermographic phosphor based on chromium(III)-doped yttrium aluminum borate (YAB) is obtained as single crystals by high temperature flux growth and as a microcrystalline powder via solution combustion synthesis. The phosphor is excitable both in the blue (λmax 422 nm) and in the red part of the spectrum (λmax 600 nm) and shows bright NIR emission. The brightness of the phosphor is comparable to that of a well-known lamp phosphor Mn(IV)-doped magnesium fluorogermanate. At ambient temperatures, the Cr(III)-doped YAB shows high temperature dependence of the luminescence decay time, which approaches 1% per deg. The material shows no decrease in luminescence intensity at higher temperatures. The new phosphor is particularly promising for applications in temperature-compensated optical chemosensors (including those based on NIR-emitting indicators) and in pressure-sensitive paints. PMID:20473368

  12. Preparation and Characterization of Chromium(III)-Activated Yttrium Aluminum Borate: A New Thermographic Phosphor for Optical Sensing and Imaging at Ambient Temperatures.

    PubMed

    Borisov, Sergey M; Gatterer, Karl; Bitschnau, Brigitte; Klimant, Ingo

    2010-05-20

    A new thermographic phosphor based on chromium(III)-doped yttrium aluminum borate (YAB) is obtained as single crystals by high temperature flux growth and as a microcrystalline powder via solution combustion synthesis. The phosphor is excitable both in the blue (lambda(max) 422 nm) and in the red part of the spectrum (lambda(max) 600 nm) and shows bright NIR emission. The brightness of the phosphor is comparable to that of a well-known lamp phosphor Mn(IV)-doped magnesium fluorogermanate. At ambient temperatures, the Cr(III)-doped YAB shows high temperature dependence of the luminescence decay time, which approaches 1% per deg. The material shows no decrease in luminescence intensity at higher temperatures. The new phosphor is particularly promising for applications in temperature-compensated optical chemosensors (including those based on NIR-emitting indicators) and in pressure-sensitive paints. PMID:20473368

  13. Synthesis and luminescence characterization of Sr(0.5)Ca(0.5)TiO3:Sm(3+) phosphor.

    PubMed

    Vidyadharan, Viji; Remya, Mohan P; Gopi, Subhash; Thomas, Sunil; Joseph, Cyriac; Unnikrishnan, N V; Biju, P R

    2015-11-01

    The spectroscopic properties of trivalent samarium doped Sr0.5Ca0.5TiO3 perovskite phosphor material (Sr0.5Ca0.5TiO3:xSm(3+), x=0.05, 0.1, 0.5, 1, 1.5) synthesized by the solid state method have been studied. The X-Ray Diffraction profile confirms the orthorhombic perovskite Sr0.5Ca0.5TiO3 structure of the prepared samples. The SEM study reveals the surface morphology. The Judd-Ofelt intensity parameters were calculated for 0.5 wt% Sm(3+) doped Sr0.5Ca0.5TiO3. Transition probabilities, branching ratios and radiative lifetime were evaluated by using Judd-Ofelt analysis. The emission spectra under 405 nm excitation shows five emission peaks at 564 nm, 599 nm, 645 nm, 707 nm and 776 nm corresponding to the transitions (4)G5/2→(6)Hj (j=5/2, 7/2, 9/2, 11/2 and 13/2) respectively. The higher values of branching ratio and stimulated emission cross-section for (4)G5/2→(6)H7/2 transition of Sr0.5Ca0.5TiO3:0.5 wt% Sm(3+) shows its suitability in the field of visible lasers and optical fiber amplifiers. The experimental lifetimes of Sm(3+) doped samples were estimated using the decay curves corresponding to (4)G5/2→(6)H7/2 transition upon 405 nm excitation. Concentration dependence on emission intensity and experimental lifetime were also studied. From the CIE diagram we can see that as the concentration of Sm(3+) ions increases from 0.05 wt% to 1.5 wt% the CIE color co-ordinates changes from greenish yellow to yellowish orange. PMID:26057096

  14. Characterizing the gender gap in introductory physics

    NASA Astrophysics Data System (ADS)

    Kost, Lauren E.; Pollock, Steven J.; Finkelstein, Noah D.

    2009-06-01

    Previous research [S. J. Pollock , Phys. Rev. ST Phys. Educ. Res. 3, 1 (2007)] showed that despite the use of interactive engagement techniques, the gap in performance between males and females on a conceptual learning survey persisted from pretest to post-test at the University of Colorado at Boulder. Such findings were counter to previously published work [M. Lorenzo , Am. J. Phys. 74, 118 (2006)]. This study begins by identifying a variety of other gender differences. There is a small but significant difference in the course grades of males and females. Males and females have significantly different prior understandings of physics and mathematics. Females are less likely to take high school physics than males, although they are equally likely to take high school calculus. Males and females also differ in their incoming attitudes and beliefs about physics. This collection of background factors is analyzed to determine the extent to which each factor correlates with performance on a conceptual post-test and with gender. Binned by quintiles, we observe that males and females with similar pretest scores do not have significantly different post-test scores (p>0.2) . The post-test data are then modeled using two regression models (multiple regression and logistic regression) to estimate the gender gap in post-test scores after controlling for these important prior factors. These prior factors account for about 70% of the observed gender gap. The results indicate that the gender gap exists in interactive physics classes at our institution but is largely associated with differences in previous physics and math knowledge and incoming attitudes and beliefs.

  15. [Study on the Preparation of Ba3Si6O9N4 : Eu(2+) Phosphor and the Characterization of Their Luminescence Properties].

    PubMed

    Pan, Hua-yan; Wang, Le; Luo, Dong; Li, Yang-hui; Zhang, Hong; Shen, Ye

    2016-03-01

    Ba3Si6O9N4 : Eu(2+) phosphors were synthesized by two-step synthesis processes based on high temperature solid phase using BaSiO3 as a precursor. The influence mechanism of the Eu(2+) doping concentration to the luminescence properties of Ba3Si6O9N4 : Eu(2+) phosphors were mainly investigated. This paper made a comparison between the luminescence properties of Ba3Si6ON4 : Eu(2+) phosphors prepared by two-step processes and solid- state reaction method. The results showed that the Ba3Si6O9N4 : Eu(3+) phosphors synthesized by two-step processes had higher purity and higher crystallinity. There exists concentration quenching in Ba3Si6O9N4 : Eu(2+) phosphors for both two-step processes and solid-state reaction when the doping concentration x is more than 9%. Both the concentration quenching mechanism of Ba3 Si 09 N4 : EuI+ phosphor prepared by solid-state reaction and two-step processes is electric dipole-dipole interaction. The emission peak of Ba3Si6O9N4 : Eu(2+) phosphors (peak 489 nm) prepared by two-step processes had a blue shift compared to the emission peak of Ba3Si6O9N4 : Eu2+ phosphors (peak 512nm) prepared by solid-state reaction. The emission peak of Ba3Si6O9N4 : Eu2+ phosphors prepared by two-step processes relatively close to the theoretical value (480 nm). The spectrum analysis result showed that the element component of Ba3Si6O3N4 : Eu2+ phosphors prepared by two-step processes was closer to the theoretical value, it means that the two-step processes can effectively reduce the lattice defects. The Ba3Si6O9N4 : Eu(2+) phosphors synthesized by two-step processes had better thermal stability, which demonstrates to be a highly promising phosphor for white-LED applications. PMID:27400500

  16. Radioluminescence Investigation Of Ion-irradiated Phosphors

    SciTech Connect

    Jacobsohn, Luiz; Muenchausen, Ross; Bennett, Bryan

    2008-01-01

    Phosphors are materials that emit light under the excitation of incoming radiation. This property is used, among other applications, in radiation detection. Efficient energy transfer from the ionization track to the luminescent centers must occur to yield significant light output. Besides, the investigation of the effects of ion irradiation on the luminescence of phosphors is comparatively unexplored. In this work, we review radioluminescence (RL) investigation of ion-irradiated oxides and oxide phosphors, and present preliminary data on the effects of ion irradiation on the luminescence of intrinsic phosphor Bi{sub 4}Ge{sub 3}0{sub 12} (BGO). Commercial crystals were irradiated, and the irradiation effects characterized by means of RL measurements as a function of temperature, from 10K to room temperature (RT), and optical absorption measurements. Overall, surface modification induced by ion irradiation leads to higher luminescence output.

  17. Physical and Electrical Characterization of Aluminum Polymer Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, David; Sampson, Michael J.

    2010-01-01

    Polymer aluminum capacitors from several manufacturers with various combinations of capacitance, rated voltage, and ESR values were physically examined and electrically characterized. The physical construction analysis of the capacitors revealed three different capacitor structures, i.e., traditional wound, stacked, and laminated. Electrical characterization results of polymer aluminum capacitors are reported for frequency-domain dielectric response at various temperatures, surge breakdown voltage, and other dielectric properties. The structure-property relations in polymer aluminum capacitors are discussed.

  18. Physical and Electrical Characterization of Polymer Aluminum Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, David; Sampson, Michael J.

    2010-01-01

    Polymer aluminum capacitors from several manufacturers with various combinations of capacitance, rated voltage, and ESR values were physically examined and electrically characterized. The physical construction analysis of the capacitors revealed three different capacitor structures, i.e., traditional wound, stacked, and laminated. Electrical characterization results of polymer aluminum capacitors are reported for frequency-domain dielectric response at various temperatures, surge breakdown voltage, and other dielectric properties. The structure-property relations in polymer aluminum capacitors are discussed.

  19. Characterization of four-color multi-package white light-emitting diodes combined with various green monochromatic phosphor-converted light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Oh, Ji Hye; Lee, Keyong Nam; Do, Young Rag

    2012-03-01

    In this study, several combinations of multi-package white light-emitting diodes (LEDs), which combine an InGaN blue LED with green, amber, and red phosphor-converted LEDs (pc-LEDs), were characterized by changing the peak wavelength of green pc-LEDs between 515nm and 560nm (515, 521, 530, 540, 550, 560nm) in color temperature of 6,500K and 3,500K. Various green monochromatic pc-LEDs were fabricated by capping a long-wave pass-filter (LWPF) on top of pc-LEDs to improve luminous efficacy and color purity. LWPF-capped green monochromatic pc-LED can address the drawback of green semiconductor-type III-V LED, such as low luminous efficacy in the region of green gap wavelength. Luminous efficacy and color rendering index (CRI) of multi-package white LEDs are compared with changing the driving current of individual LED in various multi-package white LEDs. This study provides a best combination of four-color multi-package white LEDs which has high luminous efficacy and good CRI.

  20. Structural characterization, EPR and thermoluminescence properties of Cd{sub 1−x}Ni{sub x}SiO{sub 3} nanocrystalline phosphors

    SciTech Connect

    Manjunatha, C.; Sunitha, D.V.; Nagabhushana, H.; Sharma, S.C.; Ashoka, S.; Rao, J.L.; Nagabhushana, B.M.; Chakradhar, R.P.S.

    2012-09-15

    Highlights: ► CdSiO{sub 3}:Ni{sup 3+} nanophosphorus have been prepared at much lower temperatures. ► Phosphors are well characterized by PXRD, TEM, FTIR and UV–Vis spectroscopy. ► EPR, thermo and photoluminescence properties were also reported. -- Abstract: Cd{sub 1−x}Ni{sub x}SiO{sub 3} (x = 1–7 mol%) nanophosphors have been prepared for the first time by the combustion method using oxylyldihydrizide as a fuel. Powder X-ray diffraction results confirm the formation of monoclinic phase. Scanning electron micrographs show that Ni{sup 2+} influences the porosity of samples. The optical energy gap is widened with increase of Ni{sup 2+} ion dopant. The electron paramagnetic resonance spectrum of Ni{sup 2+} ions in CdSiO{sub 3} exhibits a symmetric absorption at g = 2.343 and the site symmetry around Ni{sup 2+} ions is predominantly octahedral. The number of spins participating in resonance (N) and the paramagnetic susceptibility (χ) has been evaluated. The thermoluminescence intensity is found to increase up to ∼20 min ultra-violet exposure and thereafter, decrease with further increase of ultra-violet dose. The kinetic parameters such as activation energy (E), frequency factor (s) and order of kinetics was estimated using glow peak shape method and the results are discussed.

  1. Physical characterization of magmatic liquids. Final report

    SciTech Connect

    Manghnani, M.H.

    1991-12-31

    Long-range goals of this research project are: (1) Characterization of seismic velocity and attenuation (V{sub p}, V{sub S}, Q{sub p}{sup {minus}1}, Q{sup S}{sup {minus}1}) and electrical properties of selected Hawaiian and related rocks under appropriate controlled environments of pressure, temperature and volatile/fluid content; and, (2) Characterization of the elastic, viscoelastic and thermodynamic properties (V{sub p}, V{sub S}, Q{sub P}{sup {minus}1}, Q{sub S}{sup {minus}1}, viscosity and compressibility) of molten basalts, picrites and komatites, and related silicate melts to {approximately} 1600{degrees}C using the ultrasonic interferometry method. In addition, the pressure dependences of V{sub p},V{sub S} and bulk modulus will be determined using the Brillouin scattering and diamond- anvil cell techniques.

  2. Characterization and nultivariate analysis of physical properties of processing peaches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Characterization of physical properties of fruits represents the first vital step to ensure optimal performance of fruit processing operations and is also a prerequisite in the development of new processing equipment. In this study, physical properties of engineering significance to processing of th...

  3. Challenging and development of phosphors for lighting applications

    NASA Astrophysics Data System (ADS)

    Panatarani, Camellia; Joni, I. Made

    2016-02-01

    Phosphors (inorganics luminescent material) have been extensively investigated due to their potential application especially for lighting. This article briefly reviews the developments of the phosphors for lighting application. Research and development of phosphors for the application of energy-saving lamps have been developed in the Laboratory of Instrumentation System and Functional Materials Processing, Department of Physics, Universitas Padjadjaran. To fulfill the desired feature for lighting application, we developed host-center type phosphor with compositional modifications prepared by spray pyrolysis and simple solution routes. In order to meet the industry requirement with high production rate, currently we scaled up the spray pyrolysis utilized with a pulse combustion reactor.

  4. Characterizing Student Experiences in Physics Competitions: The Power of Emotions

    NASA Astrophysics Data System (ADS)

    Moll, Rachel F.; Nashon, S.; Anderson, D.

    2006-12-01

    Low enrolment and motivation are key issues in physics education and recently the affective dimension of learning is being studied for evidence of its influence on student attitudes towards physics. Physics Olympics competitions are a novel context for stimulating intense emotional experiences. In this study, one team of students and their teacher were interviewed and observed prior to and during the event to characterize their emotions and determine the connections between their experiences and learning and attitudes/motivation towards physics. Results showed that certain types of events stimulated strong emotions of frustration and ownership, and that students’ attitudes were that physics is fun, diverse and relevant. Analysis of these themes indicated that the nature of emotions generated was connected to their attitudes towards physics. This finding points to the potential and value of informal and novel contexts in creating strong positive emotions, which have a strong influence on student attitudes towards physics.

  5. Physical characterization of gravitaxis in Euglena gracilis.

    PubMed

    Lebert, M; Porst, M; Richter, P; Hader, D P

    1999-09-01

    Gravitaxis in unicellular microorganisms like Euglena gracilis has been known for more than 100 years. The current model explains this phenomenon on the basis of a specific density difference between cell body and surrounding medium. In order to test the feasibility of the current model in terms of physical considerations the specific density of different Euglena gracilis cultures was determined. Depending on the culture conditions the specific density was in a range between 1.046 g mL-1 and 1.054 g mL-1. Size and gravitaxis measurements were performed in parallel, which allowed to relate the force applied to the lower membrane to the kinetic properties of gravitactic reorientation. A linear relationship between force and gravitaxis kinetics was found. A comparison between estimated activation energy of the proposed stretch-sensitive ion channels and energy supplied by the displacement of the lower membrane by the sedimentation of the cell body revealed that a focusing, an amplification and/or an integration period over time must be involved in the gravitactic signal transduction chain. Analysis of stimulus-response curves revealed an integration period of about 5 seconds before a gravitactic reorientation starts. The kinetics of gravitaxis at 1 x gn, and 0.12 x gn, was found to be similar. A hypothesis is presented that explains this finding on the basis of a combination of an integration period and an all-or-none reaction during gravitactic reorientation. PMID:11542915

  6. Physical characterization of photon-counting tomosynthesis

    NASA Astrophysics Data System (ADS)

    Berggren, Karl; Lundqvist, Mats; Cederström, Björn; Danielsson, Mats E.; Fredenberg, Erik

    2015-03-01

    Tomosynthesis is emerging as a next generation technology in mammography. Combined with photon-counting detectors with the ability for energy discrimination, a novel modality is enabled — spectral tomosynthesis. Further advantages of photon-counting detectors in the context of tomosynthesis include elimination of electronic noise, efficient scatter rejection (in some geometries) and no lag. Fourier-based linear-systems analysis is a well-established method for optimizing image quality in two-dimensional x-ray systems. The method has been successfully adapted to threedimensional imaging, including tomosynthesis, but several areas need further investigation. This study focuses on two such areas: 1) Adaption of the methodology to photon-counting detectors, and 2) violation of the shift-invariance and stationarity assumptions in non-cylindrical geometries. We have developed a Fourier-based framework to study the image quality in a photon-counting tomosynthesis system, assuming locally linear, stationary, and shift-invariant system response. The framework includes a cascaded-systems model to propagate the modulation-transfer function (MTF) and noise-power spectrum (NPS) through the system. The model was validated by measurements of the MTF and NPS. High degrees of non-shift invariance and non-stationarity were observed, in particular for the depth resolution as the angle of incidence relative the reconstruction plane varied throughout the imaging volume. The largest effects on image quality in a given point in space were caused by interpolation from the inherent coordinate system of the x-rays to the coordinate system that was used for reconstruction. This study is part of our efforts to fully characterize the spectral tomosynthesis system, we intend to extend the model further to include the detective-quantum efficiency, observer modelling, and spectral effects.

  7. Characterization and application of expanded graphite modified with phosphoric acid and glucose for the removal of Ni(II) from aqueous solution

    NASA Astrophysics Data System (ADS)

    Jiang, Li; Zhang, Jian; Xu, Xiaoli; Zhang, Jie; Liu, Hai; Guo, Zizhang; Kang, Yan; Li, Yiran; Xu, Jingtao

    2015-12-01

    Three kinds of modified expanded graphite (EG), impregnated with phosphoric acid (H3PO4) (P-EG), impregnated with glucose (G-EG), and impregnated with H3PO4 and glucose (G-P-EG), were prepared under a low temperature (150 °C). The adsorption capacity of G-P-EG (Qm = 7.016 mg/g) is much higher than original expanded graphite (EG Qm = 0.423 mg/g) and other two kinds of modified expanded graphite (P-EG Qm = 0.770 mg/g; G-EG Qm = 0.507 mg/g). The physicochemical properties of EG and G-P-EG were characterized by N2 adsorption/desorption, Boehm's titration and X-ray photoelectron spectroscopy (XPS). EG exhibited higher values of BET surface area (11.357 m2/g) and total pore volume (0.0303 cm3/g) than that of G-P-EG (4.808 m3/g and 0.0109 cm3/g). However, the results of Bohm's titration and XPS showed that G-P-EG contained more surface oxygen-containing functional groups. The Ni(II) adsorption equilibrium data agreed well with the Langmuir model. And the experimental data of EG and G-P-EG fitted better by pseudo-second order model. Based on the results of batch adsorption experiments and XPS analysis, there were several possible mechanisms for Ni(II) adsorption on the G-P-EG, including chemical adsorption, cation exchange, electrostatic attraction and surface complication.

  8. Kimzeyite garnet phosphors

    DOEpatents

    Lyons, Robert Joseph

    2013-05-14

    A phosphor of formula I is included in a phosphor composition in a lighting apparatus capable of emitting white light, Ca.sub.3-x-zSr.sub.xCe.sub.zM.sup.1.sub.2M.sup.2AlSiO.sub.12 (I) wherein M.sup.1 is Hf, Zr, or a combination thereof; M.sup.2 is Al, or a combination of Al and Ga; z<3-x; and 0.2>x.gtoreq.0. The lighting apparatus includes a semiconductor light source in addition to the phosphor composition.

  9. Transmission electron microscopic examination of phosphoric acid fuel cell components

    NASA Technical Reports Server (NTRS)

    Pebler, A.

    1986-01-01

    Transmission electron microscopy (TEM) was used to physically characterize tested and untested phosphoric acid fuel cell (PAFC) components. Those examined included carbon-supported platinum catalysts, carbon backing paper, and Teflon-bonded catalyst layers at various stages of fabrication and after testing in pressurized PAFC's. Applicability of electron diffraction and electron energy loss spectroscopy for identifying the various phases was explored. The discussion focuses on the morphology and size distribution of platinum, the morphology and structural aspects of Teflon in catalyst layers, and the structural evidence of carbon corrosion. Reference is made to other physical characterization techniques where appropriate. A qualitative model of the catalyst layer that emerged from the TEM studies is presented.

  10. High temperature thermometric phosphors

    DOEpatents

    Allison, Stephen W.; Cates, Michael R.; Boatner, Lynn A.; Gillies, George T.

    1999-03-23

    A high temperature phosphor consists essentially of a material having the general formula LuPO.sub.4 :Dy.sub.(x),Eu.sub.y) wherein: 0.1 wt %.ltoreq.x.ltoreq.20 wt % and 0.1 wt %.ltoreq.y.ltoreq.20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopent. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions.

  11. Phosphors for LED lamps

    DOEpatents

    Murphy, James Edward; Manepalli, Satya Kishore; Kumar, Prasanth Nammalwar

    2013-08-13

    A phosphor, a phosphor blend including the phosphor, a phosphor prepared by a process, and a lighting apparatus including the phosphor blend are disclosed. The phosphor has the formula (Ca.sub.1-p-qCe.sub.pK.sub.q).sub.xSc.sub.y(Si.sub.1-rGa.sub.r).sub.zO.su- b.12+.delta. or derived from a process followed using disclosed amounts of reactants. In the formula, (0

  12. High temperature thermometric phosphors

    DOEpatents

    Allison, S.W.; Cates, M.R.; Boatner, L.A.; Gillies, G.T.

    1999-03-23

    A high temperature phosphor consists essentially of a material having the general formula LuPO{sub 4}:Dy{sub x},Eu{sub y} wherein: 0.1 wt % {<=} x {<=} 20 wt % and 0.1 wt % {<=} y {<=} 20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopant. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions. 2 figs.

  13. Phosphor thermometry system

    DOEpatents

    Beshears, David L.; Sitter, Jr., David N.; Andrews, William H.; Simpson, Marc L.; Abston, Ruth A.; Cates, Michael R.; Allison, Steve W.

    2000-01-01

    An apparatus for measuring the temperature of a moving substrate includes an air gun with a powder inlet port in communication with the outlet port of a powder reservoir, an air inlet port in communication with a pressurized air source, and an outlet nozzle spaced from and directed toward the moving substrate. The air gun is activated by the air pulses to spray controlled amounts of the powdered phosphor onto the moving substrate, where the phosphor assumes the temperature of the moving substrate. A laser produces light pulses, and optics direct the light pulses onto the phosphor on the moving substrate, in response to which the phosphor emits a luminescence with a decay rate indicative of the temperature of the phosphor. A collection lens is disposed to focus the luminescence, and a photodetector detects the luminescence focused by the collection lens and produces an electrical signal that is characteristic of the brightness of the luminescence. A processor analyzes the electrical signal to determine the decay characteristic of the luminescence and to determine the temperature of the phosphor from the decay characteristic.

  14. Physical property characterization of 183-H Basin sludge

    SciTech Connect

    Biyani, R.K.; Delegard, C.H.

    1995-09-20

    This document describes the characterization of 183-H Basin sludge physical properties, e.g. bulk density of sludge and absorbent, and determination of free liquids. Calcination of crucible-size samples of sludge was also done and the resulting `loss-on-ignition` was compared to the theoretical weight loss based on sludge analysis obtained from Weston Labs.

  15. Preparation and characterizations of aluminoborates powders for the development of a new generation of white phosphors for solid-state lighting

    NASA Astrophysics Data System (ADS)

    Guimarães, V. F.; Burner, P.; Maia, L. J. Q.; Ferrier, A.; Viana, B.; Gautier-Luneau, I.; Ibanez, A.

    2016-02-01

    This work is devoted to a new family of highly emissive white phosphors for solid-state lighting (SSL) applications. The phosphors, based on yttrium aluminoborates (g-YAB) compositions, were prepared from solutions by the polymeric precursor (PP) method (modified Pechini process), involving non-toxic and low cost precursors. The resulting resins were then dried at moderate temperatures. Then, a two-step annealing treatment with controlled atmospheres (pyrolysis under nitrogen and calcination under oxygen) favored the gradual oxidation of organic moieties coming from the starting materials. This allowed avoiding the formation of impurities, which are detrimental to photoluminescence (PL) emission such as pyrolytic carbon (visible light absorber) or carbonates (PL quenchers). Thus, we have synthesized glassy yttrium aluminoborate powders exhibiting intense PL emissions extended in the whole visible range leading to warm light emissions. These PL properties arise from structural defects (non-bridging oxygen or carbon impurities such as carbonyl radicals), whose energy levels are widely extended within the large bandgap of these g-YAB powders. Moreover, these samples exhibit good thermal and chemical stabilities. We determined their internal quantum yields using near ultraviolet excitations, which reached high promising values, around 80 - 90%. This new family of lanthanide-free phosphors exhibiting intense warm white emissions, with high Color Rendering Indexes (CRI), is promising for SSL through the development of phosphor coated -LED devices.

  16. Photoluminescence characterization and energy transfer of color-tunable Li6Y(BO3)3:Ce3+,Tb3+ phosphors

    NASA Astrophysics Data System (ADS)

    Guan, Anxiang; Zhou, Liya; Wang, Guofang; Gao, Fangfang; Wang, Qiuping; Chen, Xueting; Li, Yinghao

    2016-08-01

    Ce3+ and Tb3+ singly doped and co-doped Li6Y(BO3)3 (LYB) phosphors were synthesized through a solid-state reaction. The phosphors were effectively excited by 350 nm, which matched the near-UV emitting InGaN chip. Luminescence spectra and decay lifetime curves of LYB:Ce3+,Tb3+ were measured to prove energy transfer from Ce3+ to Tb3+. Through energy transfer, the intensity of the typical emission peak of Tb3+ at 546 nm in LYB:0.05Ce3+,0.03Tb3+ was approximately 1.8 times stronger than that in LYB:0.03Tb3+. The mechanism of Ce3+→Tb3+ energy transfer was a dipole-dipole interaction, and the energy transfer efficiency gradually increased to 29.27% with increasing Tb3+ doping concentration. Furthermore, the emission colors of LYB:Ce3+,Tb3+ varied from blue to green by adjusting the Ce3+/Tb3+ ratio, indicating that the phosphors could be used as blue-to-green emitting phosphors for application in ultraviolet light-emitting diodes.

  17. Characterization and luminescence properties of sol–gel derived M′-type LuTaO{sub 4}:Ln{sup 3+} (Ln = Pr, Sm, Dy) phosphors

    SciTech Connect

    Wu, Mengqiu; Liu, Xiaolin Gu, Mu; Ni, Chen; Liu, Bo; Huang, Shiming

    2014-12-15

    Graphical abstract: Emission spectra of LuTaO{sub 4}:Ln (Ln = Pr, Sm and Dy) phosphors under X-ray excitation. The insets illustrate their SEM micrographs. - Highlights: • M′-type LuTaO{sub 4}:Ln{sup 3+} (Ln = Pr, Sm, Dy) phosphors were synthesized by sol–gel technique. • The phosphors exhibited an efficient energy transfer from the host to activators. • High intensity of activator emission was achieved under X-ray excitation. • The phosphors are encouraging for application in high-spatial-resolution X-ray CT imaging. - Abstract: M′-type Lu{sub 1−x}Ln{sub x}TaO{sub 4} (Ln = Pr, Sm, Dy) phosphors have been successfully synthesized by sol–gel technique, their crystallization, morphology, photoluminescence and X-ray excited luminescence properties were investigated in detail. The phosphors had good crystallization behavior. The optimum doping concentrations of Pr{sup 3+}, Sm{sup 3+} and Dy{sup 3+} in LuTaO{sub 4} were at x = 0.003, 0.025, 0.02, respectively. They exhibited a more efficient host excitation relative to the 4f–4f excitations of the rare-earth ions, and a dominant {sup 1}D{sub 2} → {sup 3}H{sub 4}, {sup 4}G{sub 5/2} → {sup 6}H{sub 7/2} or {sup 4}F{sub 9/2} → {sup 6}H{sub 13/2} emission for Pr{sup 3+}, Sm{sup 3+} or Dy{sup 3+}, respectively, which corresponds to the average decay time of 21.7, 745.7 or 10.0 μs, respectively. It is expected that Pr{sup 3+}- or Dy{sup 3+}-doped LuTaO{sub 4} phosphors with a microsecond level decay time are very encouraging for applications in X-ray computerized tomographic imaging with high spatial resolution.

  18. Synthesis and luminescence characterization of Pr(3+) doped Sr1.5Ca0.5SiO4 phosphor.

    PubMed

    Vidyadharan, Viji; Mani, Kamal P; Sajna, M S; Joseph, Cyriac; Unnikrishnan, N V; Biju, P R

    2014-12-10

    Luminescence properties of Pr(3+) activated Sr1.5Ca0.5SiO4 phosphors synthesized by solid state reaction method are reported in this work. Blue, orange red and red emissions were observed in the Pr(3+) doped sample under 444nm excitation and these emissions are assigned as (3)P0→(3)H4, (3)P0→(3)H6 and (3)P0→(3)F4 transitions. The emission intensity shows a maximum corresponding to the 0.5wt% Pr(3+) ion. The decay analysis was done for 0.05 and 0.5wt% Pr(3+) doped samples for the transition (3)P0→(3)H6. The life times of 0.05 and 0.5wt% Pr(3+) doped samples were calculated by fitting to exponential and non-exponential curve respectively, and are found to be 156 and 105μs respectively. The non-exponential behaviour arises due to the statistical distribution of the distances between the ground state Pr(3+) ions and excited state Pr(3+) ions, which cause the inhomogeneous energy transfer rate. The XRD spectrum confirmed the triclinic phase of the prepared phosphors. The compositions of the samples were determined by the energy dispersive X-ray spectra. From the SEM images it is observed that the particles are agglomerated and are irregularly shaped. IR absorption bands were assigned to different vibrational modes. The well resolved peaks shown in the absorption spectra are identical to the excitation spectra of the phosphor samples. Pr(3+) activated Sr1.5Ca0.5SiO4 phosphors can be efficiently excited with 444nm irradiation and emit multicolour visible emissions. From the CIE diagram it can be seen that the prepared phosphor samples give yellowish-green emission. PMID:24998683

  19. Synthesis, characterization and luminescence properties of CaMoO4:Eu3+ red phosphor for use in light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Hong, Woo Tae; Lee, Joo Hyun; Jang, Hyeong Il; Yang, Hyun Kyoung; Jeong, Jung Hyun; Moon, Byung Kee

    2015-06-01

    CaMoO4:Eu3+ red phosphors were successfully synthesized by using a high-energy ball milling method. The X-ray diffraction patterns confirmed their tetragonal structure, and the field emission scanning electron microscopy images exhibited spherical particles. The photoluminescence properties (PL) of CaMoO4:Eu3+ phosphors were also studied as a function of the sintering temperature and the Eu3+ ion concentration. The PL excitation and the PL spectra demonstrated that CaMoO4 doped with 5 mol% of Eu3+ and sintered at 1200 °C showed an intense charge transfer band with a band maximum at around 303 nm and the strongest red emission at 618 nm (5D0 → 7F2) with Commision Internationale de I'Eclairage 1931 chromaticity coordinates (0.609, 0.343).

  20. Persistent luminescence, TL and OSL characterization of beta irradiated SrAl2O4:Eu2+, Dy3+ combustion synthesized phosphor

    NASA Astrophysics Data System (ADS)

    Zúñiga-Rivera, N. J.; García, R.; Rodríguez-Mijangos, R.; Chernov, V.; Meléndrez, R.; Pedroza-Montero, M.; Barboza-Flores, M.

    2014-05-01

    The persistent luminescence (PLUM), thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of strontium aluminates co-doped with Eu+2 and Dy+3 exposed to beta radiation is reported. The phosphor was synthesized by the combustion synthesis method employing a highly exothermic redox reaction between the metal nitrates [Al(NO3)3, Sr(NO3)2, Eu(NO3)3 and Dy(NO3)3] and organic fuel carbohydrazide (CH6N4O). The long decay PLUM emission, TL and OSL were measured as a function of beta radiation dose. A wide emission band centered at 510 nm (green) related to Eu2+ ions and lattice defects were observed for the synthesized samples. The presence of a variety of defects and aggregates were responsible for the observed broad 100 °C peaked TL glow curve of the irradiated sample which is composed of several overlapped TL peaks. The existence of multiple trapping levels, with different trapping/detrapping probabilities, is behind the particular features for the PLUM, TL and OSL emissions. We conclude that in the SrAl2O4:Eu2+, Dy3+ phosphors, the low temperature TL peaked around 30-75 °C is responsible for the PLUM emission and those around 100 °C were related to very stable trapping states which provide suitable radiation storage properties to be used as a PLUM/TL/OSL radiation phosphor.

  1. Luminescence characterization and electron beam induced chemical changes on the surface of ZnAl2O4:Mn nanocrystalline phosphor

    NASA Astrophysics Data System (ADS)

    Pitale, Shreyas S.; Kumar, Vinay; Nagpure, I. M.; Ntwaeaborwa, O. M.; Swart, H. C.

    2011-02-01

    Luminescence characteristics and surface chemical changes of nanocrystalline Mn2+ doped ZnAl2O4 powder phosphors are presented. Stable green cathodoluminescence (CL) or photoluminescence (PL) with a maximum at ∼512 nm was observed when the powders were irradiated with a beam of high energy electrons or a monochromatic xenon lamp at room temperature. This green emission can be attributed to the 4T1 → 6A1 transitions of the Mn2+ ion. Deconvoluted CL spectra resulted in two additional emission peaks at 539 and 573 nm that may be attributed to vibronic sideband and Mn4+ emission, respectively. The luminescence decay of the Mn2+ 512 nm emission under 457 nm excitation is single exponential with a lifetime of 5.20 ± 0.11 ms. Chemical changes on the surface of the ZnAl2O4:Mn2+ phosphor during prolonged electron beam exposure were monitored using Auger electron spectroscopy. The X-ray photoelectron spectroscopy (XPS) was used to determine the chemical composition of the possible compounds formed on the surface as a result of the prolonged electron beam exposure. The XPS data suggest that the thermodynamically stable Al2O3 layer was formed on the surface and is possibly contributing to the CL stability of ZnAl2O4:Mn phosphor.

  2. Phosphor persistence of oscilloscopic displays: a comparison of four phosphors.

    PubMed

    Di Lollo, V; Seiffert, A E; Burchett, G; Rabeeh, R; Ruman, T A

    1997-01-01

    The period for which phosphor decay remains visible after stimulus offset was assessed for four phosphors commonly used in psychophysical experiments: P4, P15, P31, and P46. Stimuli were displayed behind closed shutters which opened at various intervals after stimulus offset. Thus, the observers' responses were based solely on the visibility of phosphor persistence. We varied viewing conditions (dark-adapted vs. veiling light), type of task (detection vs. identification), and intensity of the stimuli. No detectable persistence was ever produced by the P15 phosphor. In contrast, the P31 phosphor remained visible for several hundred ms. even with a veiling light. The P4 and P46 phosphors produced persistence of intermediate durations. It is concluded that P15 is the phosphor of choice for visual experiments. PMID:9176944

  3. Characterization of high school mathematics and physics language genres

    NASA Astrophysics Data System (ADS)

    Wallace, Michelle L.

    Research indicates that language factors play a critical role in the learning of school mathematics and science. Symbols and language-forms have been created to represent and discuss mathematical ideas. Understanding language factors, therefore, is critical in improving the teaching and learning of school mathematics and science. The specific goal of this research was to characterize language genres found in secondary school mathematics and physics classrooms. The research presented here was conducted in two secondary school classrooms---one algebra and one physics---taught by the same teacher. The focus was on the discourse between the teacher and her students. In both mathematics and physics, the teacher attended to the meaning of mathematical concepts and processes, but the talk differed. Physics talk focused on developing meaning for the physics concepts through activities and discussion, which were accompanied by mathematical calculations and analyses. Algebra talk, on the other hand, was procedural and narrative in nature. Thus physics talk was more descriptive of individual concepts and situation, and was more explanatory and exploratory than algebra talk. All discourse inevitably reflects one's thinking and beliefs about the content of that discourse. Thus talking algebra and talking physics, as observed in this study, both represented the teacher's beliefs about teaching and learning and the nature of the school curriculum. Even for a teacher with a strong academic background in both mathematics and science, integrating across the curriculum can be hindered by the approved school curriculum and by the reality of the particular classroom context. Providing professional development and implementing one of several available integrated curricula would be needed if more integration were to be implemented. This study presents a literature-based description of the conceptual notion of language genre. It additionally presents a conceptualization of mathematics and

  4. Modeling granular phosphor screens by Monte Carlo methods

    SciTech Connect

    Liaparinos, Panagiotis F.; Kandarakis, Ioannis S.; Cavouras, Dionisis A.; Delis, Harry B.; Panayiotakis, George S.

    2006-12-15

    The intrinsic phosphor properties are of significant importance for the performance of phosphor screens used in medical imaging systems. In previous analytical-theoretical and Monte Carlo studies on granular phosphor materials, values of optical properties, and light interaction cross sections were found by fitting to experimental data. These values were then employed for the assessment of phosphor screen imaging performance. However, it was found that, depending on the experimental technique and fitting methodology, the optical parameters of a specific phosphor material varied within a wide range of values, i.e., variations of light scattering with respect to light absorption coefficients were often observed for the same phosphor material. In this study, x-ray and light transport within granular phosphor materials was studied by developing a computational model using Monte Carlo methods. The model was based on the intrinsic physical characteristics of the phosphor. Input values required to feed the model can be easily obtained from tabulated data. The complex refractive index was introduced and microscopic probabilities for light interactions were produced, using Mie scattering theory. Model validation was carried out by comparing model results on x-ray and light parameters (x-ray absorption, statistical fluctuations in the x-ray to light conversion process, number of emitted light photons, output light spatial distribution) with previous published experimental data on Gd{sub 2}O{sub 2}S:Tb phosphor material (Kodak Min-R screen). Results showed the dependence of the modulation transfer function (MTF) on phosphor grain size and material packing density. It was predicted that granular Gd{sub 2}O{sub 2}S:Tb screens of high packing density and small grain size may exhibit considerably better resolution and light emission properties than the conventional Gd{sub 2}O{sub 2}S:Tb screens, under similar conditions (x-ray incident energy, screen thickness)

  5. Physical characterization of wax/oil crystalline networks.

    PubMed

    Martini, Silvana; Tan, Chin Yiap; Jana, Sarbojeet

    2015-05-01

    The objective of this research was to evaluate the physical properties of different types of wax/oil systems. Olive (OO), corn (CO), soybean (SBO), sunflower (SFO), safflower (SAFO), and canola (CAO) oils were mixed with sunflower oil wax (SFOW), paraffin wax (PW), and beeswax (BW) at different concentrations (1% to 10%). Results from this study show that the physical properties of wax/oil systems is affected not only by the concentration and type of wax used, but also by the type of oil used. In general, wax/oil systems formulated with SFOW generated crystalline networks with high enthalpies (1 to 22 J/g) and high G' values (2 to 6 × 10(6) Pa) compared with the values obtained for BW and PW. SFOW crystalline networks were characterized by needle-like crystals independently of the wax concentrations and type of oil used. BW crystalline networks, however, were characterized by different crystal morphologies (needle-like or spherulites) depending on the wax concentration and type of oil used. PW samples were characterized by a crystalline network formed by needle- and platelet-like crystals. Enthalpy values of BW and PW samples were similar (0.3 to 20 J/g), but BW samples resulted in significantly higher (P < 0.05) G' values in the 5% and 10% samples with values of 3.9 × 10(6) and 6.1 × 10(5) Pa for 10% BW and PW, respectively. PMID:25850679

  6. Fracture Characterization through Multi-Physics Joint Inversion

    NASA Astrophysics Data System (ADS)

    Finsterle, S.; Edmiston, J. K.; Zhang, Y.

    2014-12-01

    Natural and man-made fractures tend to significantly impact the behavior of a subsurface system - with both desirable and undesirable consequences. Thus, the description, characterization, and prediction of fractured systems requires careful conceptualization and a defensible modeling approach that is tailored to the objectives of a specific application. We review some of these approaches and the related data needs, and discuss the use of multi-physics joint inversion techniques to identify and characterize the relevant features of the fracture system. In particular, we demonstrate the potential use of a non-isothermal, multiphase flow simulator coupled to a thermo-poro-elastic model for the calculation of observable deformations during injection-production operations. This model is integrated into a joint inversion framework for the estimation of geometrical, hydrogeological, rockmechanical, thermal, and statistical parameters representing the fractured porous medium.

  7. Oxidations of organic matter present in the phosphoric acid 54% by the ozone: characterization of groups carbonyls upstream and downstream of the ozonation

    NASA Astrophysics Data System (ADS)

    Linda, D.; Louati, A.; Chtara, C.; Kabadou, A.

    2012-02-01

    This study was focused on the oxidation of organic matter in phosphoric acid 54% by ozone. In order to understand the mechanisms involved in this process, the identification of this matter upstream and downstream of the ozonation was necessary. For the identification, after an extraction by a mixture (dichloro-methanol), the organic phase was divided into two parts: the residue and the extract:-The residue was studied by infrared spectroscopy Fourier Transform (IR-TF). It contains Kérogène which is a mixture of saturated hydrocarbons with high molecular weights. The absorption bands of the FT-IR showed that the residue contains also quantities of amino that correspond to the remains of dinoflagellate cysts, which are abundant in sediments.-The extract has been the subject of a detailed study by, chromatography on silica column, IR-TF spectroscopy and CG-SM. The passage of this extract on a silica column yielded two fractions (saturated fraction and polar fraction). Both of these fractions were analyzed by CG-SM. The yield of the reduction of the organic matter content in the phosphoric acid 54% could not exceed 29%. Therefore, we can conclude that the reduction in the rate of organic matter remains limited by the fact that some compounds are inert towards ozone.

  8. Spectroscopic and photoluminescence characterization of Dy(3+) in Sr0.5Ca0.5TiO3 phosphor.

    PubMed

    Vidyadharan, Viji; Sreeja, E; Jose, Saritha K; Joseph, Cyriac; Unnikrishnan, N V; Biju, P R

    2016-02-01

    The spectroscopic and photoluminescence characteristics of trivalent dysprosium (Dy(3+))-doped Sr0.5Ca0.5TiO3 phosphor materials synthesized via solid-state reaction method were studied. The X-ray diffraction profile confirmed the orthorhombic perovskite structure of the prepared samples. Judd-Ofelt analysis was carried out to obtain the intensity parameters and predicted radiative properties of Sr0.5Ca0.5TiO3:2wt%Dy(3+). The photoluminescence spectrum of Dy(3+)-doped Sr0.5Ca0.5TiO3 showed three emission peaks at 481, 574 and 638 nm corresponding to (4)F9/2 →(6)H15/2, (4)F9/2 →(6)H13/2 and (4)F9/2 →(6)H11/2 transitions respectively. The variation of luminescence intensity with different excitation wavelengths and Dy(3+) concentrations is discussed. The decay profiles of (4)F9/2 excited levels of Dy(3+) ions show bi-exponential behaviour and also a decrease in average lifetime with increase in Dy(3+) concentration. Yellow to blue luminescence intensity ratio, CIE chromaticity co-ordinates and correlated color temperature were also calculated for different concentrations of Dy(3+)-doped Sr0.5Ca0.5TiO3 phosphor at different λex. PMID:26032295

  9. Structural characterizations and intense green upconversion emission in Yb3+, Pr3+ co-doped Y2O3 nano-phosphor.

    PubMed

    Yadav, R S; Verma, R K; Bahadur, A; Rai, S B

    2015-02-25

    We report the structural and optical properties of Yb(3+), Pr(3+) co-doped Y2O3 nano-phosphor synthesized through solution combustion method. The structural studies reveal the nano-crystalline structure of the sample. The energy dispersive spectroscopy (EDS) measurements confirm the presence of Y, O, Pr and Yb elements in the sample. Fourier transform infrared studies show the vibrational features of the samples. The fluorescence spectra of the samples have been monitored on excitation with 976 nm and the intense green upconversion emission observed at 552 nm is due to (3)P0→(3)H5 electronic transition. The concentration of Pr(3+) ion in the sample is optimized and the fluorescence intensity is maximum at 0.08 mol% of Pr(3+). The power dependence studies reveal the involvement of two photons in the emission process. The possible mechanism of upconversion has been discussed on the basis of schematic energy level diagram. The sample annealed at higher temperature enhances the fluorescence intensity up to 8 times and this enhancement is discussed in terms of the removal of optical quenching centers. The nano-phosphor can be applicable in the field of display devices and green laser. PMID:25233026

  10. Structural characterizations and intense green upconversion emission in Yb3+, Pr3+ co-doped Y2O3 nano-phosphor

    NASA Astrophysics Data System (ADS)

    Yadav, R. S.; Verma, R. K.; Bahadur, A.; Rai, S. B.

    2015-02-01

    We report the structural and optical properties of Yb3+, Pr3+ co-doped Y2O3 nano-phosphor synthesized through solution combustion method. The structural studies reveal the nano-crystalline structure of the sample. The energy dispersive spectroscopy (EDS) measurements confirm the presence of Y, O, Pr and Yb elements in the sample. Fourier transform infrared studies show the vibrational features of the samples. The fluorescence spectra of the samples have been monitored on excitation with 976 nm and the intense green upconversion emission observed at 552 nm is due to 3P0 → 3H5 electronic transition. The concentration of Pr3+ ion in the sample is optimized and the fluorescence intensity is maximum at 0.08 mol% of Pr3+. The power dependence studies reveal the involvement of two photons in the emission process. The possible mechanism of upconversion has been discussed on the basis of schematic energy level diagram. The sample annealed at higher temperature enhances the fluorescence intensity up to 8 times and this enhancement is discussed in terms of the removal of optical quenching centers. The nano-phosphor can be applicable in the field of display devices and green laser.

  11. Phosphorous trapped within buckminsterfullerene

    NASA Astrophysics Data System (ADS)

    Larsson, J. A.; Greer, J. C.; Harneit, W.; Weidinger, A.

    2002-05-01

    Under normal circumstances, when covalent molecules form, electrons are exchanged between atoms to form bonds. However, experiment and theoretical computations reveal exactly the opposite effect for the formation of group V elements nitrogen and phosphorous encapsulated within a buckminsterfullerene molecule. The C60 carbon cage remains intact upon encapsulation of the atom, whereas the electronic charge cloud of the N or P atom contracts. We have studied the chemical, spin, and thermodynamic properties of endohedral phosphorous (P@C60) and have compared our results with earlier findings for N@C60. From a combined experimental and theoretical vantage, we are able to elucidate a model for the interaction between the trapped group V atom and the fullerene cage. A picture emerges for the electronic structure of these complexes, whereby an atom is trapped within a fullerene, and interacts weakly with the molecular orbitals of the C60 cage.

  12. Green emitting phosphors and blends thereof

    DOEpatents

    Setlur, Anant Achyut; Siclovan, Oltea Puica; Nammalwar, Prasanth Kumar; Sathyanarayan, Ramesh Rao; Porob, Digamber G.; Chandran, Ramachandran Gopi; Heward, William Jordan; Radkov, Emil Vergilov; Briel, Linda Jane Valyou

    2010-12-28

    Phosphor compositions, blends thereof and light emitting devices including white light emitting LED based devices, and backlights, based on such phosphor compositions. The devices include a light source and a phosphor material as described. Also disclosed are phosphor blends including such a phosphor and devices made therefrom.

  13. Physical and chemical characterization of waste wood derived biochars.

    PubMed

    Yargicoglu, Erin N; Sadasivam, Bala Yamini; Reddy, Krishna R; Spokas, Kurt

    2015-02-01

    Biochar, a solid byproduct generated during waste biomass pyrolysis or gasification in the absence (or near-absence) of oxygen, has recently garnered interest for both agricultural and environmental management purposes owing to its unique physicochemical properties. Favorable properties of biochar include its high surface area and porosity, and ability to adsorb a variety of compounds, including nutrients, organic contaminants, and some gases. Physical and chemical properties of biochars are dictated by the feedstock and production processes (pyrolysis or gasification temperature, conversion technology and pre- and post-treatment processes, if any), which vary widely across commercially produced biochars. In this study, several commercially available biochars derived from waste wood are characterized for physical and chemical properties that can signify their relevant environmental applications. Parameters characterized include: physical properties (particle size distribution, specific gravity, density, porosity, surface area), hydraulic properties (hydraulic conductivity and water holding capacity), and chemical and electrochemical properties (organic matter and organic carbon contents, pH, oxidation-reduction potential and electrical conductivity, zeta potential, carbon, nitrogen and hydrogen (CHN) elemental composition, polycyclic aromatic hydrocarbons (PAHs), heavy metals, and leachable PAHs and heavy metals). A wide range of fixed carbon (0-47.8%), volatile matter (28-74.1%), and ash contents (1.5-65.7%) were observed among tested biochars. A high variability in surface area (0.1-155.1g/m(2)) and PAH and heavy metal contents of the solid phase among commercially available biochars was also observed (0.7-83 mg kg(-1)), underscoring the importance of pre-screening biochars prior to application. Production conditions appear to dictate PAH content--with the highest PAHs observed in biochar produced via fast pyrolysis and lowest among the gasification

  14. Probability measurements characterizing the classicality of a physical system

    NASA Astrophysics Data System (ADS)

    Dorninger, Dietmar; Länger, Helmut

    2014-02-01

    Let S be a set of states of a physical system. The probabilities p(s) of the occurrence of an event when the system is in different states s ∈ S define a function from S to [0,1] called a multidimensional probability. When appropriately structured in respect to the order, complements and sums of functions, sets P of multidimensional probabilities give rise to the so-called algebras of S-probabilities which, in the case of classical physical systems, are Boolean algebras. Knowing only a (small) subset X of P, and not the whole of P, the question arises whether the functions of X indicate that one deals with a classical physical system or not. We will show that this question can be settled by (experimentally) finding further multidimensional probabilities which are terms of the given ones and can be precalculated by a recursive procedure depending on the number of elements of X. Our main tool for this procedure is a characterization of commuting pairs of multidimensional probabilities.

  15. Long-persistence blue phosphors

    NASA Technical Reports Server (NTRS)

    Yen, William M. (Inventor); Jia, Weiyi (Inventor); Lu, Lizhu (Inventor); Yuan, Huabiao (Inventor)

    2000-01-01

    This invention relates to phosphors including long-persistence blue phosphors. Phosphors of the invention are represented by the general formula: MO . mAl.sub.2 O.sub.3 :Eu.sup.2+,R.sup.3+ wherein m is a number ranging from about 1.6 to about 2.2, M is Sr or a combination of Sr with Ca and Ba or both, R.sup.3+ is a trivalent metal ion or trivalent Bi or a mixture of these trivalent ions, Eu.sup.2+ is present at a level up to about 5 mol % of M, and R.sup.3+ is present at a level up to about 5 mol % of M. Phosphors of this invention include powders, ceramics, single crystals and single crystal fibers. A method of manufacturing improved phosphors and a method of manufacturing single crystal phosphors are also provided.

  16. Isolation and structural characterization of sugarcane bagasse lignin after dilute phosphoric acid plus steam explosion pretreatment and its effect on cellulose hydrolysis.

    PubMed

    Zeng, Jijiao; Tong, Zhaohui; Wang, Letian; Zhu, J Y; Ingram, Lonnie

    2014-02-01

    The structure of lignin after dilute phosphoric acid plus steam explosion pretreatment process of sugarcane bagasse in a pilot scale and the effect of the lignin extracted by ethanol on subsequent cellulose hydrolysis were investigated. The lignin structural changes caused by pretreatment were identified using advanced nondestructive techniques such as gel permeation chromatography (GPC), quantitative (13)C, and 2-D nuclear magnetic resonance (NMR). The structural analysis revealed that ethanol extractable lignin preserved basic lignin structure, but had relatively lower amount of β-O-4 linkages, syringyl/guaiacyl units ratio (S/G), p-coumarate/ferulate ratio, and other ending structures. The results also indicated that approximately 8% of mass weight was extracted by pure ethanol. The bagasse after ethanol extraction had an approximate 22% higher glucose yield after enzyme hydrolysis compared to pretreated bagasse without extraction. PMID:24412855

  17. Design, Preparation, and Characterization of a Novel Red Long-Persistent Perovskite Phosphor: Ca3Ti2O7:Pr3+.

    PubMed

    Wang, Bo; Lin, Hang; Xu, Ju; Chen, Hui; Lin, Zebin; Huang, Feng; Wang, Yuansheng

    2015-12-01

    Currently, the development of efficient red-emitting persistent phosphor is still an ongoing challenge. Herein, a novel red-emitting LPL phosphor Ca3Ti2O7:Pr(3+) is successfully prepared by a high-temperature solid-state method. XRD Rietveld refinement analyses demonstrate the high phase purity of the sample which crystallizes in an orthorhombic Ccm21 space group with lattice parameters of a = 5.7702(5) Å, b = 19.4829(7) Å, and c = 5.1214(2) Å. Electronic structure of the host matrix is analyzed by the first-principle calculation using CASTEP code. The calculation results show that Ca3Ti2O7 has a direct band gap with CB and VB mainly composed of the Ti-3d and O-2p states, respectively. On the basis of the DR spectrum, the band gap is determined to be 3.6 eV. It is demonstrated that the 612 nm red-emitting persistent luminescence of Ca3Ti2O7:Pr(3+) can be either activated by Ti(4+)-O(2-) → Ti(3+)-O(-) host absorption and Pr(3+)-O-Ti(4+) → Pr(4+)-O-Ti(3+) IVCT in the UV region, or Pr(3+):(3)H4 → (3)PJ transition in the blue region. The red afterglow can last for ∼ 5 min observed by the naked eyes in the dark after ceasing the irradiation source. On the basis of the TL analyses, the trap is found exponentially distributed in the host with the depth of 0.69-0.92 eV. Finally, a possible LPL mechanism for Ca3Ti2O7:Pr(3+) is proposed. PMID:26561233

  18. Towards a Physical Characterization of Large Coronal Holes

    NASA Astrophysics Data System (ADS)

    Miralles, M. P.; Cranmer, S. R.; Kohl, J. L.

    2004-05-01

    The Ultraviolet Coronagraph Spectrometer (UVCS) aboard SOHO was used to observe O VI (103.2 and 103.7 nm) and H I Lyman alpha (121.6 nm) emission lines as a function of heliocentric distance in more than 85 coronal holes, in order to characterize the physical properties of coronal holes at different phases of the solar cycle. Our previous analyses of UVCS observations have shown that polar and equatorial coronal holes produce different acceleration profiles and have different oxygen kinetic temperatures. We examine the variation in the characteristics of representative large coronal holes producing a variety of high-speed conditions at 1 AU. This work is supported by NASA under Grant NAG5-12865 to the Smithsonian Astrophysical Observatory, by the Italian Space Agency and by PRODEX (Swiss contribution).

  19. Physical and chemical characterization techniques for metallic powders

    SciTech Connect

    Slotwinski, J. A.; Stutzman, P. E.; Ferraris, C. F.; Watson, S. S.; Peltz, M. A.; Garboczi, E. J.

    2014-02-18

    Systematic studies have been carried out on two different powder materials used for additive manufacturing: stainless steel and cobalt-chrome. An extensive array of characterization techniques were applied to these two powders. The physical techniques included laser-diffraction particle-size analysis, X-ray computed tomography for size and shape analysis, and optical and scanning electron microscopy. Techniques sensitive to chemistry included X-ray diffraction and energy-dispersive analytical X-ray analysis. The background of these techniques will be summarized and some typical findings comparing different samples of virgin additive manufacturing powders, taken from the same lot, will be given. The techniques were used to confirm that different samples of powder from the same lot were essentially identical, within the uncertainty of the measurements.

  20. Physical Characterization and Steam Chemical Reactivity of Carbon Fiber Composites

    SciTech Connect

    Anderl, Robert Andrew; Pawelko, Robert James; Smolik, Galen Richard

    2001-05-01

    This report documents experiments and analyses that have been done at the Idaho National Engineering and Environmental Laboratory (INEEL) to measure the steam chemical reactivity of two types of carbon fiber composites, NS31 and NB31, proposed for use at the divertor strike points in an ITER-like tokamak. These materials are 3D CFCs constituted by a NOVOLTEX preform and densified by pyrocarbon infiltration and heat treatment. NS31 differs from NB31 in that the final infiltration was done with liquid silicon to reduce the porosity and enhance the thermal conductivity of the CFC. Our approach in this work was twofold: (1) physical characterization measurements of the specimens and (2) measurements of the chemical reactivity of specimens exposed to steam.

  1. Characterizing the Evolution and Variation of Major Physics Textbooks

    NASA Astrophysics Data System (ADS)

    Campbell, Jennifer; Stewart, John

    2008-04-01

    The linguistic and structural properties of two major physics textbooks are compared. The structure of each textbook is measured and differences in the amount of space, words, and mathematics devoted to different parts of the text are reported. The linguistic richness of each text and each textual part is measured using LEXX. The readability of each textbook is characterized using standard readability formulas. A new readability formula that corrects for mathematics is proposed. The evolution of one of the textbooks over a fifteen year (four versions of the text) time span is also investigated. The reading difficulty of the textbook increased by approximately one-half a grade level over fifteen years. The lexical richness of the textbook also increased over the same period.

  2. High Extraction Phosphors for Solid State Lighting

    SciTech Connect

    Summers, Chris; Menkara, Hisham; Wagner, Brent

    2011-09-01

    We have developed high-index, high efficiency bulk luminescent materials and novel nano-sized phosphors for improved solid-state white LED lamps. These advances can potentially contribute to reducing the loss in luminous efficiencies due to scattering, re-absorption, and thermal quenching. The bulk and nanostructured luminescent materials investigated are index matched to GaN and have broad and size-tunable absorption bands, size and impurity tuned emission bands, size-driven elimination of scattering effects, and a separation between absorption and emission bands. These innovations were accomplished through the use of novel synthesis techniques suitable for high volume production for LED lamp applications. The program produced a full-color set of high quantum yield phosphors with high chemical stability. In the bulk phosphor study, the ZnSeS:Cu,Ag phosphor was optimized to achieve >91% efficiency using erbium (Er) and other activators as sensitizers. Detailed analysis of temperature quenching effects on a large number of ZnSeS:Cu,Ag,X and strontium- and calcium-thiogallate phosphors lead to a breakthrough in the understanding of the anti-quenching behavior and a physical bandgap model was developed of this phenomena. In a follow up to this study, optimized phosphor blends for high efficiency and color performance were developed and demonstrated a 2-component phosphor system with good white chromaticity, color temperature, and high color rendering. By extending the protocols of quantum dot synthesis, large nanocrystals, greater than 20 nm in diameter were synthesized and exhibited bulk-like behavior and blue light absorption. The optimization of ZnSe:Mn nanophosphors achieved ~85% QE The limitations of core-shell nanocrystal systems were addressed by investigating alternative deltadoped structures. To address the manufacturability of these systems, a one-pot manufacturing protocol was developed for ZnSe:Mn nanophosphors. To enhance the stability of these material

  3. Physical model for characterizing and simulating a FLOTOX EEPROM device

    NASA Astrophysics Data System (ADS)

    Wu, Ching-Yuan; Chen, Chiou-Feng

    1992-05-01

    A physical model has been developed to analyze the dynamic characteristics of a FLOTOX EEPROM device. The effects of the structural parameters such as the area and thickness of the tunneling-oxide and interpoly-oxide layers are characterized by a coupling ratio to describe the discrete programming or erasing operation. The physical parameters including the electron trapping and positive-charge generation effects are used to describe the endurance and retention operations of an EEPROM device. Computer simulations based on this model have been performed to analyze the operations of an EEPROM device, including the effects of three different programming/erasing input voltage waveforms (pulse, exponential rise and triangular). A method for protecting an EEPROM device from overshooting or undershooting during programming or erasing operation is proposed. Therefore, the proposed model can be used as a computer-aided-design (CAD) tool for device design and an efficient simulation tool for describing the dynamic operation and reliability of an EEPROM device.

  4. Application of physical and chemical characterization techniques to metallic powders

    SciTech Connect

    Slotwinski, J. A.; Watson, S. S.; Stutzman, P. E.; Ferraris, C. F.; Peltz, M. A.; Garboczi, E. J.

    2014-02-18

    Systematic studies have been carried out on two different powder materials used for additive manufacturing: stainless steel and cobalt-chrome. The characterization of these powders is important in NIST efforts to develop appropriate measurements and standards for additive materials and to document the property of powders used in a NIST-led additive manufacturing material round robin. An extensive array of characterization techniques was applied to these two powders, in both virgin and recycled states. The physical techniques included laser diffraction particle size analysis, X-ray computed tomography for size and shape analysis, and optical and scanning electron microscopy. Techniques sensitive to chemistry, including X-ray diffraction and energy dispersive analytical X-ray analysis using the X-rays generated during scanning electron microscopy, were also employed. Results of these analyses will be used to shed light on the question: how does virgin powder change after being exposed to and recycled from one or more additive manufacturing build cycles? In addition, these findings can give insight into the actual additive manufacturing process.

  5. Characterization of the physical properties for solid granular materials

    SciTech Connect

    Tucker, Jonathan R.; Shadle, Lawrence J.; Guenther, Chris; Benyahia, Sofiane; Mei, Joseph S.; Banta, Larry

    2012-01-01

    Accurate prediction of the behavior of a system is strongly governed by the components within that system. For multiphase systems incorporating solid powder-like particles, there are many different physical properties which need to be known to some level of accuracy for proper design, modeling, or data analysis. In the past, the material properties were determined initially as a secondary part of the study or design. In an attempt to provide results with the least level of uncertainty, a procedure was developed and implemented to provide consistent analysis of several different types of materials. The properties that were characterized included particle sizing and size distributions, shape analysis, density (particle, skeletal and bulk), minimum fluidization velocities, void fractions, particle porosity, and assignment within the Geldart Classification. In the methods used for this experiment, a novel form of the Ergun equation was used to determine the bulk void fractions and particle density. Materials of known properties were initially characterized to validate the accuracy and methodology, prior to testing materials of unknown properties. The procedures used yielded valid and accurate results, with a high level of repeatability. A database of these materials has been developed to assist in model validation efforts and future designs. It is also anticipated that further development of these procedures wil be expanded increasing the properties included in the database.

  6. Physical and chemical methods for the characterization of hazardous wastes

    NASA Astrophysics Data System (ADS)

    Francis, C. W.; Maskarinec, M. P.; Lee, D. W.

    Numerous test methods have been proposed and developed to evaluate the hazards associated with handling and disposal of wastes in landfills. The major concern is the leaching of toxic constituents from the wastes. The fate of hazardous constituents in landfilled wastes is highly dependent on the physical and chemical characteristics of the waste. Thus, the primary objective in the selection of waste characterization procedures should be focused on those methods that gauge the fate of the waste's hazardous constituents in a specific landfill environment. Waste characterization in the United States has centered around the characteristics of ignitability, corrosivity, reactivity, and toxicity. The strategy employed in the development of most regulatory waste characterization procedures has been a pass or fail approach, usually tied to some form of a mismanagement scenario for that waste. For example, USEPA has chosen the disposal of a waste in a municipal waste landfill as a mismanagement scenario for the development of the waste leaching tests to determine the toxicity characteristic. Many wastes, such as large-volume utility wastes or mining wastes, are not disposed of in municipal waste landfills. As a consequence, more effort is needed in the development of waste leaching tests that determine the long-term leaching characteristics of that waste in the landfill environment in which the waste is to be disposed. Waste leaching models also need to be developed and tested as to their ability to simulate actual disposal environments. These models need to be compared with laboratory leaching tests, and, if practical, coupled with groundwater transport models.

  7. Physical and psychophysical characterization of a novel clinical system for digital mammography

    SciTech Connect

    Rivetti, Stefano; Lanconelli, Nico; Bertolini, Marco; Borasi, Giovanni; Golinelli, Paola; Acchiappati, Domenico; Gallo, Ennio

    2009-11-15

    panels: The MTF values of the AMULET system are about 45% and 15% at 5 and 8 lp/mm, respectively. On the other hand, however, AMULET NNPS results are consistently better than those from direct-conversion flat panels (up to two to three times lower) and flat panels based on scintillation phosphors. DQE results lie around 70% when RQA-M2 beams are used and approaches 80% in the case of W/Rh beams. Contrast-detail analysis, when performed by human observers on the AMULET system, results in values better than those published for other full-field digital mammography systems. Conclusions: The novel clinical unit based on direct-conversion detector and optical reading presents great results in terms of both physical and psychophysical characterizations. The good spatial resolution, combined with excellent noise properties, allows the achievement of very good DQE, better than those published for clinical FFDM systems. The psychophysical analysis confirms the excellent behavior of the AMULET unit.

  8. Phosphor-Free Solid State Light Sources

    SciTech Connect

    Nause, Jeff E; Ferguson, Ian; Doolittle, Alan

    2007-02-28

    The objective of this work was to demonstrate a light emitting diode that emitted white light without the aid of a phosphor. The device was based on the combination of a nitride LED and a fluorescing ZnO substrate. The early portion of the work focused on the growth of ZnO in undoped and doped form. The doped ZnO was successfully engineered to emit light at specific wavelengths by incorporating various dopants into the crystalline lattice. Thereafter, the focus of the work shifted to the epitaxial growth of nitride structures on ZnO. Initially, the epitaxy was accomplished with molecular beam epitaxy (MBE). Later in the program, metallorganic chemical vapor deposition (MOCVD) was successfully used to grow nitrides on ZnO. By combining the characteristics of the doped ZnO substrate with epitaxially grown nitride LED structures, a phosphor-free white light emitting diode was successfully demonstrated and characterized.

  9. Synthesis and characterization of (3-Aminopropyl)trimethoxy-silane (APTMS) functionalized Gd2O3:Eu3+ red phosphor with enhanced quantum yield

    NASA Astrophysics Data System (ADS)

    Jain, Akhil; Hirata, G. A.; Farías, M. H.; Castillón, F. F.

    2016-02-01

    We report the surface modification of nanocrystalline Gd2O3:Eu3+ phosphor by (3-Aminopropyl)trimethoxysilane (APTMS). The nanoparticles were first coated with silica using the Stöber process, and then annealed at 650 °C for 2 h. Afterwards, APTMS was functionalized onto the silica layer to obtain Gd2O3:Eu3+ nanoparticles bearing amine groups on the surface. The effect of silica coating, and the subsequent annealing process on the crystallization of the nanophosphor were analyzed by x-ray diffraction (XRD). High-resolution transmission electron microscopy (HR-TEM) confirmed the presence of a silica layer of ∼45 nm thickness. X-ray photoelectron (XPS) and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of silica and the amine groups. Photoluminescence (PL) analysis demonstrated an increased emission after functionalization of nanoparticles. Absolute quantum yield (QY) measurements revealed an 18% enhancement in QY in functionalized nanoparticles compared with unmodified nanoparticles, which is of great importance for their biomedical applications.

  10. Synthesis and characterization of (3-Aminopropyl)trimethoxy-silane (APTMS) functionalized Gd2O3:Eu(3+) red phosphor with enhanced quantum yield.

    PubMed

    Jain, Akhil; Hirata, G A; Farías, M H; Castillón, F F

    2016-02-12

    We report the surface modification of nanocrystalline Gd2O3:Eu(3+) phosphor by (3-Aminopropyl)trimethoxysilane (APTMS). The nanoparticles were first coated with silica using the Stöber process, and then annealed at 650 °C for 2 h. Afterwards, APTMS was functionalized onto the silica layer to obtain Gd2O3:Eu(3+) nanoparticles bearing amine groups on the surface. The effect of silica coating, and the subsequent annealing process on the crystallization of the nanophosphor were analyzed by x-ray diffraction (XRD). High-resolution transmission electron microscopy (HR-TEM) confirmed the presence of a silica layer of ∼45 nm thickness. X-ray photoelectron (XPS) and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of silica and the amine groups. Photoluminescence (PL) analysis demonstrated an increased emission after functionalization of nanoparticles. Absolute quantum yield (QY) measurements revealed an 18% enhancement in QY in functionalized nanoparticles compared with unmodified nanoparticles, which is of great importance for their biomedical applications. PMID:26684579

  11. Observation, identification and characterization of strong self-reduction process in a orthophosphate phosphor CaZr{sub 4}(PO{sub 4}){sub 6}:Eu

    SciTech Connect

    Zhu, Ge; Shi, Yurong; Mikami, Masayoshi; Shimomura, Yasuo; Wang, Yuhua

    2014-02-01

    Highlights: • CaZr{sub 4}P{sub 4}O{sub 24}:Eu was synthesized by solid state reaction in air. • Relationship between the structure and luminescence properties was discussed. • Strong self-reduction process was found in CaZr{sub 4}P{sub 4}O{sub 24}:Eu prepared in air. • Oxidation states of Eu were identified by muti-method approaches. • The self-reduction mechanism was investigated. - Abstract: CaZr{sub 4}P{sub 4}O{sub 24}:Eu orthophosphate phosphor was synthesized by traditional solid state reaction in air atmosphere. The relationship between the host structure and the characteristic luminescence properties was discussed detailedly. When irradiate the sample under 365 nm UV lamp, intense green emission was observed due to the strong self-reduction process of Eu ions. The oxidation states of Eu ions were identified by muti-method approaches, including photoluminescence spectra, fluorescence lifetimes, Electron spin resonance (ESR) spectroscopy and X-ray photoelectron spectroscopy analysis (XPS). The self-reduction process was controlled by adding the charge compensator Li{sub 2}CO{sub 3} and the self-reduction mechanism was further investigated.

  12. Characterizing interactive engagement activities in a flipped introductory physics class

    NASA Astrophysics Data System (ADS)

    Wood, Anna K.; Galloway, Ross K.; Donnelly, Robyn; Hardy, Judy

    2016-06-01

    Interactive engagement activities are increasingly common in undergraduate physics teaching. As research efforts move beyond simply showing that interactive engagement pedagogies work towards developing an understanding of how they lead to improved learning outcomes, a detailed analysis of the way in which these activities are used in practice is needed. Our aim in this paper is to present a characterization of the type and duration of interactions, as experienced by students, that took place during two introductory physics courses (1A and 1B) at a university in the United Kingdom. Through this work, a simple framework for analyzing lectures—the framework for interactive learning in lectures (FILL), which focuses on student interactions (with the lecturer, with each other, and with the material) is proposed. The pedagogical approach is based on Peer Instruction (PI) and both courses are taught by the same lecturer. We find lecture activities can be categorized into three types: interactive (25%), vicarious interactive (20%) (involving questions to and from the lecturer), and noninteractive (55%). As expected, the majority of both interactive and vicarious interactive activities took place during PI. However, the way that interactive activities were used during non-PI sections of the lecture varied significantly between the two courses. Differences were also found in the average time spent on lecturer-student interactions (28% for 1A and 12% for 1B), although not on student-student interactions (12% and 12%) or on individual learning (10% and 7%). These results are explored in detail and the implications for future research are discussed.

  13. Preparation and mechanical properties of the MgAl2O4 transparent phosphor ceramics

    NASA Astrophysics Data System (ADS)

    Bai, Xue; Li, Zhen; Lei, Muyun; Pang, Zhenli

    2014-09-01

    MgAl2O4 transparent phosphor ceramics were fabricated by hot-pressing and hot isostatic pressing using high-purity ultrafine MgAl2O4 powder mixed with phosphor. The microstructures of transparent phosphor ceramics were characterized by SEM and EDS. Moreover, the hardness and bending strength of transparent ceramics were measured. Effect of phosphor concentration (0~20%) on microstructure, hardness and bending flexture of transparent ceramics was analyzed. It was found that phosphor doping plays an important role in improving the mechanical property of transparent ceramics. So applying this kind of transparent phosphor ceramic to LED components as packaging material can significantly improve the lifetime and reliability of LED products.

  14. Improved measurement precision in decay time-based phosphor thermometry

    NASA Astrophysics Data System (ADS)

    Abou Nada, F.; Knappe, C.; Aldén, M.; Richter, M.

    2016-06-01

    This study comprises a continuation of the previous efforts of the authors to characterize different sources of errors in phosphor thermometry based on the determination of luminescence decays from thermographic phosphors. Whereas earlier investigations focused on point detectors utilizing different sensor technology, this work presents a comparison of four PMTs that are identical in terms of their product type. These detectors are supposedly identical, but the investigations revealed that their response is strictly individual. This study also shows a linear excitation energy dependence for the decay time of cadmium tungstate (CdWO4), the phosphor being used in this work. In addition, the potential influence of the intense and short fluorescence peak preceding the weaker and longer exponential decay in some phosphor materials was investigated using the electrical signal gating capability of the PMT. Finally, the evaluated decay time also appeared to be affected by the oscilloscope settings used when recording the phosphorescence signals. The presented results indicate that all operating parameters from the calibration measurement need to be rigorously reproduced in order to avoid systematic temperature errors in phosphor thermometry experiments that are based on reproducible measurements of the decay time. These results should be of more general interest also outside the phosphor community as the findings, presented herein, in principal concern all kinds of measurements that are dependent on reproducible measurements of signal shapes or time transients.

  15. Ancient mortars from Cape Verde: mineralogical and physical characterization

    NASA Astrophysics Data System (ADS)

    Rocha, Fernando; Costa, Cristiana; Velosa, Ana; Quintela, Ana; Terroso, Denise; Marques, Vera

    2014-05-01

    Times and locations of different building constructions means different knowledge, habits, different construction methods and materials. The study and safeguarding of the architectural heritage takes nowadays a progressive importance as a vehicle for transmission of cultures and history of nations. The coatings are of great importance in the durability of a building due to the protective role of the masonry. The compatibility between the materials with which they are executed (masonry, mortar and grout settlement) promotes the proper functioning of the wall and a consequent increase in durability. Therefore, it becomes important to study and characterize the mortar coating of buildings to know its characteristics and to use compatible materials in the rehabilitation and maintenance of buildings. This study aims to characterize the chemical, physical, mechanical and mineralogical mortar samples collected in buildings in three islands of Cape Verde, for the conservation, rehabilitation and preservation of them. The collected samples belong to buildings constructed in the end of XIX century and in the beginning of XX century. In order to characterize the mortar samples some tests was made, such as X-Ray Diffraction, X- Ray Fluorescence, acid attack and mechanical strength. The samples were divided into three groups depending on origin; so we have a first group collected on the island of Santiago, the second on the island of Saint Vincent and the third on the island of Santo Antao. The samples are all carbonated, but Santiago samples have a lower carbonates content. In terms of insoluble residue (from the acid attack) it was concluded that the samples have similar value ranging from 9 to 26%. The compressive strength of the mortars have a range between 1.36 and 4.55 MPa, which is related to the presence of more binder in samples with higher resistance. The chemical and mineralogical analyzes showed that these consist of lime mortars (binder), natural pozzolan and

  16. Physical properties of inulin and inulin-orange juice: physical characterization and technological application.

    PubMed

    Saavedra-Leos, M Z; Leyva-Porras, C; Martínez-Guerra, E; Pérez-García, S A; Aguilar-Martínez, J A; Álvarez-Salas, C

    2014-05-25

    In this work two systems based on a carbohydrate polymer were studied: inulin as model system and inulin-orange juice as complex system. Both system were stored at different water activity conditions and subsequently characterized. Water adsorption isotherms type II were fitted by the GAB model and the water monolayer content was determined for each system. From thermal analyzes it was found that at low water activities (aw) systems were fully amorphous. As aw increased, crystallinity was developed. This behavior was corroborated by X-ray diffraction. In the inulin-orange juice system, crystallization appears at lower water activity caused by the intensification of the chemical interaction of the low molecular weight species contained in orange juice. Glass transition temperature (Tg), determined by modulated differential scanning calorimeter, decreased with aw. As water is adsorbed, the physical appearance of samples changed which could be observed by optical microscopy and effectively related with the microstructure found by scanning electron microscopy. PMID:24708946

  17. Physical characterization of quantum devices from nonlocal correlations

    NASA Astrophysics Data System (ADS)

    Bancal, Jean-Daniel; Navascués, Miguel; Scarani, Valerio; Vértesi, Tamás; Yang, Tzyh Haur

    2015-02-01

    In the device-independent approach to quantum information theory, quantum systems are regarded as black boxes that, given an input (the measurement setting), return an output (the measurement result). These boxes are then treated regardless of their actual internal working. In this paper we develop swap, a theoretical concept that, in combination with the tool of semidefinite methods for the characterization of quantum correlations, allows us to estimate physical properties of the black boxes from the observed measurement statistics. We find that the swap tool provides bounds orders of magnitude better than previously known techniques (e.g., for a Clauser-Horne-Shimony-Holt violation larger than 2.57, swap predicts a singlet fidelity greater than 70 % ). This method also allows us to deal with hitherto intractable cases such as robust device-independent self-testing of nonmaximally entangled two-qutrit states in the Collins-Gisin-Linden-Massar-Popescu scenario (for which Jordan's lemma does not apply) and the device-independent certification of entangled measurements. We further apply the swap method to relate nonlocal correlations to work extraction and quantum dimensionality, hence demonstrating that this tool can be used to study a wide variety of properties relying on the sole knowledge of accessible statistics.

  18. N-Methylmelamines: Synthesis, Characterization, and Physical Properties.

    PubMed

    List, Manuela; Puchinger, Helmut; Gabriel, Herbert; Monkowius, Uwe; Schwarzinger, Clemens

    2016-05-20

    N-Methylmelamines have recently gained importance as valuable compounds for manufacturing modified melamine formaldehyde resins and other polymer building blocks. A great advantage of these polymers is the reduction of the carcinogenic formaldehyde. Selecting the polymerization processes (e.g., substance polymerization, polymerization in solution) and controlling the polymerization reaction and properties of these novel materials requires knowledge of the properties of the individual melamine derivatives used as new building blocks. All possible permutations of N-methylmelamines were prepared, and reaction progress was monitored by GC/MS. 2,4,6-Tris(dimethylamino)-1,3,5-triazine was prepared to complete the series; this is, however, also a possible byproduct in various synthesis routes. The reaction conditions were optimized to obtain high yields of each derivative with the highest possible purity. The substances were characterized by NMR and IR spectroscopy, mass spectrometry, elemental analysis, and single-crystal X-ray diffraction. In addition, physical properties, such as solubility, melting points, and pKb values, were determined. The number of amino-, methylamino-, and dimethylamino groups has a significant effect on these properties. In summary, we found that by increasing the number of amino- and methylamino groups, solubility and pKb increase. With increasing number of amino groups, the compounds tend to form hydrogen bonds, and thus, the melting point shifts to higher temperature ranges where they start to decompose. PMID:27100712

  19. Cathode catalyst for primary phosphoric fuel cells

    NASA Technical Reports Server (NTRS)

    Walsh, F.

    1980-01-01

    Alkylation of Vulcan XC-72 provided the most stable bond type for linking CoTAA to the surface of the carbon; this result is based on data obtained by cyclic voltammetry, pulse voltammetry and by release of 14C from bonded CoTAA. Half-cell tests at 100 C in 85% phosphoric acid showed that CoTAA bonded to the surface of carbon (Vulcan XC-72) via an alkylation procedure is a more active catalyst than is platinum based on a factor of two improvement in Tafel slope; dimeric CoTAA has catalytic activity equal to platinum. Half-cell tests also showed that bonded CoTAA catalysts do not suffer a loss in potential when air is used as a fuel rather than oxygen. Commercially available PTFE was shown to be stable for four months in 200 C 85% phosphoric acid based on lack of change in surface wetting properties, IR and physical characteristics. When stressed electrochemically in 150 C 85% phosphoric acid, PTFE also showed no changes after one month.

  20. Single-Layer, Multicolor Electroluminescent Phosphors

    NASA Technical Reports Server (NTRS)

    Robertson, James B.

    1988-01-01

    Etching eliminated in producing phosphor layers for displays. New process enables production of single-layer, two-color phosphor layer without etching. Method of construction, beginning with glass substrate with electrode and insulator layers, involves deposition of green phosphor masking with metal mask or photoresist; diffusion or ion implantation of manganese through mask to produce red phosphor and removal of mask.

  1. Molten salt synthesis, characterization, and luminescence properties of GdNbO{sub 4}/LuTaO{sub 4}:Eu{sup 3+} phosphors

    SciTech Connect

    Lin, Jintai; Zhou, Zhan; Wang, Qianming

    2013-08-01

    Graphical abstract: Well crystallized GdNbO4:Eu3{sup +} and LuTaO{sub 4}:Eu3{sup +} in the presence of fluxes were formed under reduced temperature in contrast to conventional method and their photophysical properties were studied. - Highlights: • Molten salt method was used to assemble two phosphors. • Both GdNbO{sub 4}:Eu{sup 3+} and LuTaO{sub 4}:Eu{sup 3+} could be red emissive. • The two powders were well dispersed as nano-particles. - Abstract: GdNbO{sub 4}:Eu{sup 3+} and LuTaO{sub 4}:Eu{sup 3+} have been successfully prepared with different fluxes (NaCl, KCl, NaCl and KCl) by the molten salt method. X-ray diffraction (XRD) patterns illustrated that well crystallized GdNbO{sub 4}:Eu{sup 3+} and LuTaO{sub 4}:Eu{sup 3+} in the presence of fluxes were formed under reduced temperature (900 °C) in contrast to conventional method (GdNbO{sub 4}:Eu{sup 3+}: around 1200 °C; LuTaO{sub 4}:Eu{sup 3+}: around 1500 °C). Scanning electron microscope (SEM) images revealed that well dispersed particles were achieved (granular or rod-like structures). Meanwhile, the photo-luminescent studies demonstrated that both niobate and tantalate are efficient hosts to sensitize europium red emissions. The results indicated that GdNbO{sub 4}:Eu{sup 3+} using NaCl as the flux gave much enhanced red emission whereas LuTaO{sub 4}:Eu{sup 3+} synthesized with the assistance of mixed salts (NaCl–KCl) achieved the best luminescence.

  2. Polymorphism of phosphoric oxide

    USGS Publications Warehouse

    Hill, W.L.; Faust, G.T.; Hendricks, S.B.

    1943-01-01

    The melting points and monotropic relationship of three crystalline forms of phosphoric oxide were determined by the method of quenching. Previous vapor pressure data are discussed and interpreted to establish a pressure-temperature diagram (70 to 600??) for the one-component system. The system involves three triple points, at which solid, liquid and vapor (P4O10) coexist in equilibrium, namely: 420?? and 360 cm., 562?? and 43.7 cm. and 580?? and 55.5 cm., corresponding to the hexagonal, orthorhombic and stable polymorphs, respectively, and at least two distinct liquids, one a stable polymer of the other, which are identified with the melting of the stable form and the hexagonal modification, respectively. Indices of refraction of the polymorphs and glasses were determined. The density and the thermal, hygroscopic and structural properties of the several phases are discussed.

  3. Characterization of scatter in digital mammography from physical measurements

    SciTech Connect

    Leon, Stephanie M. Wagner, Louis K.; Brateman, Libby F.

    2014-06-15

    .16, and the MRE ranged from about 3 to 13 mm. Without a grid, the SF ranged from a minimum of 0.25 to a maximum of 0.52, and the MRE ranged from about 20 to 45 mm. The SF with a grid demonstrated a mild dependence on target/filter combination and kV, whereas the SF without a grid was independent of these factors. The MRE demonstrated a complex relationship as a function of kV, with notable difference among target/filter combinations. The primary source of change in both the SF and MRE was phantom thickness. Conclusions: Because breast tissue varies spatially in physical density and elemental content, the effective thickness of breast tissue varies spatially across the imaging field, resulting in a spatially-variant scatter distribution in the imaging field. The data generated in this study can be used to characterize the scatter contribution on a point-by-point basis, for a variety of different techniques.

  4. Custom blending of lamp phosphors

    NASA Technical Reports Server (NTRS)

    Klemm, R. E.

    1978-01-01

    Spectral output of fluorescent lamps can be precisely adjusted by using computer-assisted analysis for custom blending lamp phosphors. With technique, spectrum of main bank of lamps is measured and stored in computer memory along with emission characteristics of commonly available phosphors. Computer then calculates ratio of green and blue intensities for each phosphor according to manufacturer's specifications and plots them as coordinates on graph. Same ratios are calculated for measured spectrum. Once proper mix is determined, it is applied as coating to fluorescent tubing.

  5. Combustion synthesis of borate phosphors

    NASA Astrophysics Data System (ADS)

    Thakare, D. S.; Omanwar, S. K.; Moharil, S. V.; Dhopte, S. M.; Muthal, P. L.; Kondawar, V. K.

    2007-08-01

    A fast and simple method of preparation, based on the combustion synthesis, is described for the synthesis of borate based PL phosphors which can be used for commercial lamp applications. Phosphors with various structures, incorporating different activators could be successfully prepared. PL intensities of (Gd0.6Ce0.2Tb0.2)MgB5O10, SrB4O7:Eu2+ and La0.88Gd0.1Bi0.02B3O6 were found to be comparable with those of the corresponding commercial phosphors.

  6. Physical Characterization of Tropical Oceanic Convection Observed in KWAJEX.

    NASA Astrophysics Data System (ADS)

    Yuter, Sandra E.; Houze, Robert A., Jr.; Smith, Eric A.; Wilheit, Thomas T.; Zipser, Edward

    2005-04-01

    The Tropical Rainfall Measuring Mission (TRMM) Kwajalein Experiment (KWAJEX) was designed to obtain an empirical physical characterization of precipitating convective clouds over the tropical ocean. Coordinated datasets were collected by three aircraft, one ship, five upper-air sounding sites, and a variety of continuously recording remote and in situ surface-based sensors, including scanning Doppler radars, profilers, disdrometers, and rain gauges. This paper describes the physical characterization of the Kwajalein cloud population that has emerged from analyses of datasets that were obtained during KWAJEX and combined with long-term TRMM ground validation site observations encompassing three rainy seasons. The spatial and temporal dimensions of the precipitation entities exhibit a lognormal probability distribution, as has been observed over other parts of the tropical ocean. The diurnal cycle of the convection is also generally similar to that seen over other tropical oceans. The largest precipitating cloud elements—those with rain areas exceeding 14 000 km2—have the most pronounced diurnal cycle, with a maximum frequency of occurrence before dawn; the smallest rain areas are most frequent in the afternoon. The large systems exhibited stratiform rain areas juxtaposed with convective regions. Frequency distributions of dual-Doppler radar data showed narrow versus broad spectra of divergence in the stratiform and convective regions, respectively, as expected because strong up- and downdrafts are absent in the stratiform regions. The dual-Doppler profiles consistently showed low-level convergence and upper-level divergence in convective regions and midlevel convergence sandwiched between lower- and upper-level divergence in stratiform regions. However, the magnitudes of divergence are sensitive to assumptions made in classifying the radar echoes as convective or stratiform. This sensitivity implies that heating profiles derived from satellite radar data will be

  7. Surface Patterning of Ceramic Phosphor Plate for Light Extraction

    NASA Astrophysics Data System (ADS)

    Mao, An

    Light-Emitting Diodes (LEDs) are expected to replace traditional lighting sources in the near future due to their energy-efficiency, optical design flexibility and good reliability over traditional lighting sources. III-V nitride blue LEDs with powdered phosphors have been used commercially to get white emission. However, due to scattering losses, thermal issues as well as the surface reactivity with common encapsulants, LEDs fabricated with powdered phosphors have limitations in achieving high luminous efficacy, high chromatic stability and good color-rendering properties. Solid, non-scattering phosphors could avoid many of these limitations, but issues of light extraction and coupling of excitation radiation to the phosphor require development to insure efficient operation. Photonic crystal structures fabricated into or on non-scattering phosphors can be used to address these challenges. In this thesis, a lift-off process with bilayer resist system is developed to create nanopatterns. A photonic crystal structure is fabricated by low cost molecular transfer lithography (MxL) with bi-layer resist system on non-scattering phosphor plate used for white emission to increase the extraction efficiency. In Chapter 1, some basic background concepts which appear frequently in this thesis are introduced. These concepts include the Stokes shift and backscattering phenomenon for powder phosphors as well as non-scattering phosphors. In Chapter 2, a non-scattering single crystal phosphor with a patterned surface is proposed to replace the powdered phosphors used for color converted LEDs. A non-scattering phosphor YAG:Ce ceramic phosphor plate (CPP) patterned with TiO2 photonic crystal structure is selected for convenience to demonstrate the concept. The physical origin of light extraction of the proposed structure is discussed. The simulation principles and results are discussed in this chapter to find the optimized photonic crystal structure for light extraction. In Chapter 3

  8. Characterizing, modeling, and addressing gender disparities in introductory college physics

    NASA Astrophysics Data System (ADS)

    Kost-Smith, Lauren Elizabeth

    2011-12-01

    The underrepresentation and underperformance of females in physics has been well documented and has long concerned policy-makers, educators, and the physics community. In this thesis, we focus on gender disparities in the first- and second-semester introductory, calculus-based physics courses at the University of Colorado. Success in these courses is critical for future study and careers in physics (and other sciences). Using data gathered from roughly 10,000 undergraduate students, we identify and model gender differences in the introductory physics courses in three areas: student performance, retention, and psychological factors. We observe gender differences on several measures in the introductory physics courses: females are less likely to take a high school physics course than males and have lower standardized mathematics test scores; males outscore females on both pre- and post-course conceptual physics surveys and in-class exams; and males have more expert-like attitudes and beliefs about physics than females. These background differences of males and females account for 60% to 70% of the gender gap that we observe on a post-course survey of conceptual physics understanding. In analyzing underlying psychological factors of learning, we find that female students report lower self-confidence related to succeeding in the introductory courses (self-efficacy) and are less likely to report seeing themselves as a "physics person". Students' self-efficacy beliefs are significant predictors of their performance, even when measures of physics and mathematics background are controlled, and account for an additional 10% of the gender gap. Informed by results from these studies, we implemented and tested a psychological, self-affirmation intervention aimed at enhancing female students' performance in Physics 1. Self-affirmation reduced the gender gap in performance on both in-class exams and the post-course conceptual physics survey. Further, the benefit of the self

  9. Radionuclide concentrations in raw and purified phosphoric acids from Brazil and their processing wastes: implications for radiation exposures.

    PubMed

    da Conceição, Fabiano Tomazini; Antunes, Maria Lúcia Pereira; Durrant, Steven F

    2012-02-01

    Radionuclides from the U and Th natural series are present in alkaline rocks, which are used as feedstock in Brazil for the production of raw phosphoric acid, which can be considered as a NORM (naturally occurring radioactive material). As a result of the purification of raw phosphoric acid to food-grade phosphoric acid, two by-products are generated, i.e., solid and liquid wastes. Taking this into account, the main aim of this study was to evaluate the fluxes of natural radionuclide in the production of food-grade phosphoric acids in Brazil, to determine the radiological impact caused by ingestion of food-grade phosphoric acid, and to evaluate the solid waste environmental hazards caused by its application in crop soils. Radiological characterization of raw phosphoric acid, food-grade phosphoric acid, solid waste, and liquid waste was performed by alpha and gamma spectrometry. The (238)U, (234)U, (226)Ra, and (232)Th activity concentrations varied depending on the source of raw phosphoric acid. Decreasing radionuclides activity concentrations in raw phosphoric acids used by the producer of the purified phosphoric acid were observed as follows: Tapira (raw phosphoric acid D) > Catalão (raw phosphoric acids B and C) > Cajati (raw phosphoric acid A). The industrial purification process produces a reduction in radionuclide activity concentrations in food-grade phosphoric acid in relation to raw phosphoric acid produced in plant D and single raw phosphoric acid used in recent years. The most common use of food-grade phosphoric acid is in cola soft drinks, with an average consumption in Brazil of 72 l per person per year. Each liter of cola soft drink contains 0.5 ml of food-grade phosphoric acid, which gives an annual average intake of 36 ml of food-grade phosphoric acid per person. Under these conditions, radionuclide intake through consumption of food-grade phosphoric acid per year per person via cola soft drinks is not hazardous to human health in Brazil

  10. Fully phosphor-converted LEDs with Lumiramic phosphor technology

    NASA Astrophysics Data System (ADS)

    Bechtel, Helmut; Schmidt, Peter J.; Tücks, Andreas; Heidemann, Matthias; Chamberlin, Danielle; Müller-Mach, Regina; Müller, Gerd O.; Shchekin, Oleg

    2010-08-01

    Fully phosphor-converted LEDs (FpcLeds) with saturated emission have been realized in the green and amber spectral region. With the Lumiramic phosphor technology it is possible to achieve high package efficiency with minimum transmission of blue light from the primary LED source. This is done by keeping the scattering properties of the phosphor layer low while the phosphor thickness is chosen to fully convert all blue LED emission. It is shown that this can be done not only for optically isotropic Lumiramic materials like garnets, but also for oxonitridosilicate materials like the green emitting Europium doped SrSi2O2N2, crystallizing in a triclinic lattice with three optical axes. The scattering power of the Lumiramic can be decreased to acceptable levels by increasing the size of the crystallites in the densely sintered ceramics. Light propagation is found to be described well with Mie scattering of mono-sized SrSi2O2N2 spheres with refraction index differing by 0.07 to the refractive index of a SrSi2O2N2 matrix material. Using this technology, the green-yellow gap of visible light emitting LEDs can be bridged and color tunable lamps with the efficiency and flux of today's white phosphor-converted LEDs become feasible.

  11. Laser-activated remote phosphor conversion with ceramic phosphors

    NASA Astrophysics Data System (ADS)

    Lenef, Alan; Kelso, John; Tchoul, Maxim; Mehl, Oliver; Sorg, Jörg; Zheng, Y.

    2014-09-01

    Direct laser activation of a remote phosphor, or LARP, is a highly effective approach for producing very high luminance solid-state light sources. Such sources have much smaller étendue than LEDs of similar power, thereby greatly increasing system luminous fluxes in projection and display applications. While several commercial products now employ LARP technology, most current configurations employ phosphor powders in a silicone matrix deposited on rotating wheels. These provide a low excitation duty cycle that helps limit quenching and thermal overload. These systems already operate close to maximum achievable pump powers and intensities. To further increase power scaling and eliminate mechanical parts to achieve smaller footprints, OSRAM has been developing static LARP systems based on high-thermal conductivity monolithic ceramic phosphors. OSRAM has recently introduced a static LARP product using ceramic phosphor for endoscopy and also demonstrated a LARP concept for automotive forward lighting1. We first discuss the basic LARP concept with ceramic phosphors, showing how their improved thermal conductivity can achieve both high luminous fluxes and luminance in a static configuration. Secondly, we show the importance of scattering and low optical losses to achieving high overall efficiency and light extraction. This is shown through experimental results and radiation transport calculations. Finally, we discuss some of the fundamental factors which limit the ultimate luminance achievable with ceramic converted LARP, including optical pumping effects and thermal quenching.

  12. Reactivity of the cadmium ion in concentrated phosphoric acid solutions.

    PubMed

    De Gyves, J; Gonzales, J; Louis, C; Bessiere, J

    1989-07-01

    The solvation transfer coefficients which characterize the changes of ion reactivity with phosphoric acid concentration have been calculated for cadmium from the constants of the successive chloride complexes, and for silver and diethyldithiophosphate from potentiometric measurements. They evidence the strong desolvation of the cadmium species in concentrated phosphoric acid media, causing a remarkable increase of its reactivity. They allow the results of liquid-liquid extraction, precipitation and flotation reactions to be correctly interpreted and their changes to be foreseen when the reagents are modified. PMID:18964794

  13. Micro-electro-mechanical systems phosphoric acid fuel cell

    DOEpatents

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

    2010-08-17

    A phosphoric acid fuel cell system comprising a porous electrolyte support, a phosphoric acid electrolyte in the porous electrolyte support, a cathode electrode contacting the phosphoric acid electrolyte, and an anode electrode contacting the phosphoric acid electrolyte.

  14. Micro-electro-mechanical systems phosphoric acid fuel cell

    DOEpatents

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

    2010-12-21

    A phosphoric acid fuel cell system comprising a porous electrolyte support, a phosphoric acid electrolyte in the porous electrolyte support, a cathode electrode contacting the phosphoric acid electrolyte, and an anode electrode contacting the phosphoric acid electrolyte.

  15. Inorganic Phosphor Materials for Lighting.

    PubMed

    Lin, Yuan-Chih; Karlsson, Maths; Bettinelli, Marco

    2016-04-01

    This chapter addresses the development of inorganic phosphor materials capable of converting the near UV or blue radiation emitted by a light emitting diode to visible radiation that can be suitably combined to yield white light. These materials are at the core of the new generation of solid-state lighting devices that are emerging as a crucial clean and energy saving technology. The chapter introduces the problem of white light generation using inorganic phosphors and the structure-property relationships in the broad class of phosphor materials, normally containing lanthanide or transition metal ions as dopants. Radiative and non-radiative relaxation mechanisms are briefly described. Phosphors emitting light of different colors (yellow, blue, green, and red) are described and reviewed, classifying them in different chemical families of the host (silicates, phosphates, aluminates, borates, and non-oxide hosts). This research field has grown rapidly and is still growing, but the discovery of new phosphor materials with optimized properties (in terms of emission efficiency, chemical and thermal stability, color, purity, and cost of fabrication) would still be of the utmost importance. PMID:27573146

  16. High-speed phosphor thermometry.

    PubMed

    Fuhrmann, N; Baum, E; Brübach, J; Dreizler, A

    2011-10-01

    Phosphor thermometry is a semi-invasive surface temperature measurement technique utilising the luminescence properties of doped ceramic materials. Typically, these phosphor materials are coated onto the object of interest and are excited by a short UV laser pulse. Up to now, primarily Q-switched laser systems with repetition rates of 10 Hz were employed for excitation. Accordingly, this diagnostic tool was not applicable to resolve correlated temperature transients at time scales shorter than 100 ms. This contribution reports on the first realisation of a high-speed phosphor thermometry system employing a highly repetitive laser in the kHz regime and a fast decaying phosphor. A suitable material was characterised regarding its temperature lifetime characteristic and its measurement precision. Additionally, the influence of laser power on the phosphor coating was investigated in terms of heating effects. A demonstration of this high-speed technique has been conducted inside the thermally highly transient system of an optically accessible internal combustion engine. Temperatures have been measured with a repetition rate of 6 kHz corresponding to one sample per crank angle degree at 1000 rpm. PMID:22047319

  17. Physical and chemical characterization of Dead Sea mud

    SciTech Connect

    Khlaifat, Abdelaziz; Al-Khashman, Omar; Qutob, Hani

    2010-05-15

    A laboratory analysis was performed to determine the physical and chemical properties of 24 Dead Sea mud samples collected from three different locations on the eastern shore of the Dead Sea. Several analytical techniques were used to determine the chemical and mineralogical compositions of those samples including atomic absorption spectrometry and X-ray diffraction. Physical parameters such as specific gravity, Atterberg limits, grain size, specific surface area, cation exchange capacity, pH and electrical conductivity were also studied. The main focus of the work was to document mud characteristics and to study the interrelation between physical and chemical properties. The mud samples were quite rich in minerals. Strontium was the most abundant trace element in the samples (range: 410-810 ppm) followed by barium (range: 155-380 ppm), vanadium (range: 209-264 ppm) and lead (range: 108-114 ppm). There were significant differences in the elemental contents of mud samples collected from different locations.

  18. Chemical and photoluminescence analyses of new carbon-based boron oxynitride phosphors

    SciTech Connect

    Wang, Wei-Ning; Kaihatsu, Yutaka; Iskandar, Ferry; Okuyama, Kikuo

    2009-11-15

    Analyses of newly developed carbon-based boron oxynitride phosphors using an electron energy-loss spectrometer and a spectroflurophotometer were carried out. The results showed that the prepared phosphor powder has covalently bonded boron, nitrogen, and oxygen atoms with a soft carbon framework. Photoluminescence characterization revealed that the resultant phosphor has a direct bandgap transition with defect broadened band edges, resulting in a high quantum efficiency, because the atomic distances of the phosphor are smaller than those of conventional carbon-based boron nitride compounds, which have an indirect bandgap transition and a low quantum efficiency. The atomic distances of the phosphor are smaller owing to the presence of oxygen atoms, which have a higher electron affinity and a smaller covalent bond radius compared with boron, carbon and nitrogen.

  19. Characterization of physical and aerodynamic properties of walnuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to study the physical and aerodynamic properties of freshly harvested walnuts. Measurements were carried out for three walnut varieties, Tulare, Howard and Chandler cultivated in California, USA. The nuts treated with and without Ethephon were collected from mechan...

  20. Characterizing Interactive Engagement Activities in a Flipped Introductory Physics Class

    ERIC Educational Resources Information Center

    Wood, Anna K.; Galloway, Ross K.; Donnelly, Robyn; Hardy, Judy

    2016-01-01

    Interactive engagement activities are increasingly common in undergraduate physics teaching. As research efforts move beyond simply showing that interactive engagement pedagogies work towards developing an understanding of "how" they lead to improved learning outcomes, a detailed analysis of the way in which these activities are used in…

  1. CHEMICAL AND PHYSICAL CHARACTERIZATION OF MUNICIPAL SLUDGE INCINERATOR EMISSIONS

    EPA Science Inventory

    Particulate emissions form a group of municipal sludge incinerators, three with multiple-hearth furnaces and one with a fluidized-bed furnace, were characterized. Objectives of the investigation were (1) to obtain specific elemental emission concentrations, and (2) to provide sou...

  2. 21 CFR 582.1073 - Phosphoric acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Phosphoric acid. 582.1073 Section 582.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance...

  3. 21 CFR 582.1073 - Phosphoric acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Phosphoric acid. 582.1073 Section 582.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance...

  4. 21 CFR 182.1073 - Phosphoric acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance...

  5. 21 CFR 582.1073 - Phosphoric acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Phosphoric acid. 582.1073 Section 582.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance...

  6. 21 CFR 182.1073 - Phosphoric acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance...

  7. 21 CFR 582.1073 - Phosphoric acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Phosphoric acid. 582.1073 Section 582.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance...

  8. 21 CFR 182.1073 - Phosphoric acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Phosphoric acid. 182.1073 Section 182.1073 Food... GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is generally recognized as safe when used...

  9. 21 CFR 182.1073 - Phosphoric acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is...

  10. 21 CFR 182.1073 - Phosphoric acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance...

  11. 21 CFR 582.1073 - Phosphoric acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Phosphoric acid. 582.1073 Section 582.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance...

  12. Radioactivity measurements using storage phosphor technology

    SciTech Connect

    Cheng, Y.T.; Hwang, J.; Hutchinson, M.R.

    1995-12-31

    We propose to apply a recently developed charged particle radiation imaging concept in bio-medical research for fast, cost-effective characterization of radionuclides in contaminated sites and environmental samples. This concept utilizes sensors with storage photostimulable phosphor (SPP) technology as radiation detectors. They exhibit high sensitivity for all types of radiation and the response is linear over a wide dynamic range (>10{sup 5}), essential for quantitative analysis. These new sensors have an active area of up to 35 cm x 43 cm in size and a spatial resolution as fine as 50 {mu}m. They offer considerable promise as large area detectors for fast characterization of radionuclides with an added ability to locate and identify hot spots.

  13. Unique characterization of lunar samples by physical properties

    NASA Technical Reports Server (NTRS)

    Todd, T.; Richter, D. A.; Simmons, G.; Wang, H.

    1973-01-01

    The measurement of compressional velocity, shear velocity, static compressibility, and thermal expansion of (1) a suite of shocked rocks fron the Ries impact in Germany, (2) a suite of samples cracked by thermal cycling to high temperatures, (3) many terrestrial igneous rocks, and (4) lunar basalts, gabbroic anorthosites, and breccias, indicate that shock metamorphism is the primary cause for values of physical properties of lunar rocks being diffferent from their intrinsic values. Large scale thermal metamorphism, thermal cycling between temperatures of lunar day and night, large thermal gradients, or thermal fatigue could possibly cause minor cracking in the top few centimeters of the lunar regolith, but are probably not important mechanism for extensively changing values of physical properties of lunar rocks.-

  14. Characterization of physically vapor deposited AF2400 thin films

    SciTech Connect

    Chow, R.; Spragge, M.K.; Loomis, G.E.; Rainer, F.; Ward, R.; Thomas, I.M.; Kozlowski, M.R.

    1993-11-01

    Anti-reflective coatings made with Teflon AF2400 had the highest damage thresholds recorded for physical vapor deposited coatings at the Lawrence Livermore National Laboratory damage facility. Physical vapor deposited layers of Teflon AF2400, a perfluorinated amorphous polymer, maintained the bulk optical properties of a high transmittance from 200 nm to 1600 nm, and a low refractive index. In addition, the refractive index can be intentionally reduced by control of two common deposition parameters, deposition rate and substrate temperature. Scanning electron microscopy and nuclear magnetic resonance observations indicated that morphological changes caused the variations in the refractive index rather than compositional changes. The coatings adhered to fused silica and silicon wafers under normal laboratory handling conditions.

  15. Physical Characterization of TNOs with the James Webb Space Telescope

    NASA Astrophysics Data System (ADS)

    Parker, Alex; Pinilla-Alonso, Noemi; Santos-Sanz, Pablo; Stansberry, John; Alvarez-Candal, Alvaro; Bannister, Michele; Benecchi, Susan; Cook, Jason; Fraser, Wesley; Grundy, Will; Guilbert, Aurelie; Merline, Bill; Moullet, Arielle; Mueller, Michael; Olkin, Cathy; Ragozzine, Darin

    2016-01-01

    Studies of the physical properties of trans-Neptunian objects (TNOs) are a powerful probe into the processes of planetesimal formation and solar system evolution. James Webb Space Telescope (JWST) will provide unique new capabilities for such studies. Here, we outline where the capabilities of JWST open new avenues of investigation, potentially valuable observations and surveys, and conclude with a discussion of community actions that may serve to enhance the eventual science return of JWST's TNO observations.

  16. Hydrothermal synthesis and photoluminescence of SrWO{sub 4}:Tb{sup 3+} novel green phosphor

    SciTech Connect

    Liao Jinsheng; Qiu Bao; Wen Herui; Chen Jinglin; You Weixiong

    2009-09-15

    Tb{sup 3+}-doped SrWO{sub 4} phosphors with a scheelite structure have been prepared by hydrothermal reaction. X-ray powder diffraction, field-emission scanning electron microscopy, photoluminescence excitation and emission spectra and decay curve were used to characterize the resulting samples. Scanning electron microscopy image showed that the obtained SrWO{sub 4}:Tb{sup 3+} phosphors appeared to be nearly spherical and their sizes ranged from 1 to 3 {mu}m. Photoluminescence spectra indicated the phosphors emitted strong green light centered at 545 nm under ultraviolet light excitation. Because 12 at.% SWO{sub 4}:Tb{sup 3+} phosphor exhibits intensive green emission under 254 nm excitation in comparison with the commercial green fluorescent lamp phosphor (LaPO{sub 4}:Ce,Tb), the excellent luminescence properties make it a new promising green phosphor for fluorescent lamps application.

  17. Physical and Chemical Characterization of Carbonaceous Aerosols in Korea

    NASA Astrophysics Data System (ADS)

    Choung, S.; Jin, J. S.; Hwang, G. S.; Jang, K. S.; Han, W. S.; OH, J.; Kwon, Y.

    2014-12-01

    Atmospheric aerosols have been recently paid attention more in environmental research due to their negative effects on air quality, public health, and climate change. The aerosols contain approximately >20-50% carbonaceous components such as organic carbon (OC) and black carbon (BC) (or elemental carbon [EC]) derived from organic compounds, biomass burning, and incomplete combustion of fossil fuels. The physical, chemical, and biological properties of atmospheric aerosols are strongly dependent on the carbonaceous components. In particular, the BC could significantly affect the regional air quality in the northeastern Asia, because China is one of the foremost BC emission country in the world. Previous studies have mainly focused on the quantification and source identification for carbonaceous aerosols. However, understanding of physical and chemical properties for the carbonaceous aerosols related to environmental contamination and toxicity was still incomplete due to analytical difficulties. This study is addressed to evaluate the contribution of carbonaceous aerosols to air pollution through the surface, mass spectroscopic, and electron microscopic analyses, and determination of chemical composition and structure using the air particulate matter (PM2.5 and >PM2.5) samples.

  18. Toward a Physical Characterization of Raindrop Collision Outcome Regimes

    NASA Technical Reports Server (NTRS)

    Testik, F. Y.; Barros, Ana P.; Bilven, Francis L.

    2011-01-01

    A comprehensive raindrop collision outcome regime diagram that delineates the physical conditions associated with the outcome regimes (i.e., bounce, coalescence, and different breakup types) of binary raindrop collisions is proposed. The proposed diagram builds on a theoretical regime diagram defined in the phase space of collision Weber numbers We and the drop diameter ratio p by including critical angle of impact considerations. In this study, the theoretical regime diagram is first evaluated against a comprehensive dataset for drop collision experiments representative of raindrop collisions in nature. Subsequently, the theoretical regime diagram is modified to explicitly describe the dominant regimes of raindrop interactions in (We, p) by delineating the physical conditions necessary for the occurrence of distinct types of collision-induced breakup (neck/filament, sheet, disk, and crown breakups) based on critical angle of impact consideration. Crown breakup is a subtype of disk breakup for lower collision kinetic energy that presents distinctive morphology. Finally, the experimental results are analyzed in the context of the comprehensive collision regime diagram, and conditional probabilities that can be used in the parameterization of breakup kernels in stochastic models of raindrop dynamics are provided.

  19. Bioclimatic and physical characterization of the world’s islands

    PubMed Central

    Weigelt, Patrick; Jetz, Walter; Kreft, Holger

    2013-01-01

    The Earth’s islands harbor a distinct, yet highly threatened, biological and cultural diversity that has been shaped by geographic isolation and unique environments. Island systems are key natural laboratories for testing theory in ecology and evolution. However, despite their potential usefulness for research, a quantitative description of island environments and an environmental classification are still lacking. Here, we prepare a standardized dataset and perform a comprehensive global environmental characterization for 17,883 of the world’s marine islands >1 km2 (∼98% of total island area). We consider area, temperature, precipitation, seasonality in temperature and precipitation, past climate change velocity, elevation, isolation, and past connectivity—key island characteristics and drivers of ecosystem processes. We find that islands are significantly cooler, wetter, and less seasonal than mainlands. Constrained by their limited area, they show less elevational heterogeneity. Wet temperate climates are more prevalent on islands, whereas desert climates are comparatively rare. We use ordination and clustering to characterize islands in multidimensional environmental space and to delimit island ecoregions, which provides unique insights into the environmental configuration and diversity of the world’s islands. Combining ordination and classification together with global environmental data in a common framework opens up avenues for a more integrative use of islands in biogeography, macroecology, and conservation. To showcase possible applications of the presented data, we predict vascular plant species richness for all 17,883 islands based on statistically derived environment–richness relationships. PMID:24003123

  20. Timing properties of phosphor-coated polished LSO crystals.

    PubMed

    Schmall, Jeffrey P; Roncali, Emilie; Berg, Eric; Viswanath, Varsha; Du, Junwei; Cherry, Simon R

    2014-08-01

    This study investigates a time-of-flight (TOF)-depth-of-interaction (DOI) detector design for positron emission tomography (PET), based on phosphor-coated lutetium oxyorthosilicate (LSO) scintillator crystals coupled to fast single channel photomultiplier tubes. Interaction of the scintillation light with the phosphor coating changes the pulse shape in a depth-dependent manner. 3 × 3 × 10 mm(3) LSO scintillation crystals with polished surfaces were characterized, with and without phosphor coating, to assess DOI capability and timing properties. Two different phosphor coating geometries were studied: coating of the top surface of the crystal, and the top plus half of the crystal sides. There was negligible depth dependency in the decay time when coating only the top surface, however there was a ∼10 ns difference in end-to-end decay time when coating the top plus half of the crystal sides, sufficient to support the use of three DOI bins (3.3 mm DOI bin width). The rise time of the half-coated phosphor crystal was slightly faster at all depths, compared to uncoated crystals, however the signal amplitude was lower. Phosphor coating resulted in depth-dependent photopeak positions with an energy resolution of 13.7%, at a depth of 1 mm, and 15.3%, at a depth of 9 mm, for the half-coated crystal. Uncoated LSO crystals showed no change in photopeak position as a function of depth, with an energy resolution of 10.4%. The head-on coincidence timing resolution (CTR) of two uncoated LSO crystals was 287 ps using constant fraction discrimination for time pick-off. With phosphor coating, the CTR of the top-coated crystal was 314 ps, compared to 384 ps for the half-coated crystal. We demonstrate that the trade-off between timing resolution and DOI resolution can be controlled by the phosphor coating geometry. Here we present preliminary results demonstrating that good DOI resolution can be achieved with only a modest 26% degradation in CTR. PMID:25047008

  1. Thermoluminescence glow curve analysis and CGCD method for erbium doped CaZrO3 phosphor

    NASA Astrophysics Data System (ADS)

    Tiwari, Ratnesh; Chopra, Seema

    2016-05-01

    The manuscript report the synthesis, thermoluminescence study at fixed concentration of Er3+ (1 mol%) doped CaZrO3 phosphor. The phosphors were prepared by modified solid state reaction method. The powder sample was characterized by thermoluminescence (TL) glow curve analysis. In TL glow curve the optimized concentration in 1mol% for UV irradiated sample. The kinetic parameters were calculated by computerized glow curve deconvolution (CGCD) techniaue. Trapping parameters gives the information of dosimetry loss in prepared phosphor and its usability in environmental monitoring and for personal monitoring. CGCD is the advance tool for analysis of complicated TL glow curves.

  2. Study of optical properties of cerium ion doped barium aluminate phosphor

    NASA Astrophysics Data System (ADS)

    Lohe, P. P.; Omanwar, S. K.; Bajaj, N. S.; Belsare, P. D.

    2016-05-01

    In the recent years due to their various optical and technological applications aluminate materials have attracted attention of several researchers. When these materials are doped with rare earth ions they show properties favorable for many optical applications such as high quantum efficiencies. These materials are used in various applications such as lamp phosphors, optically and thermoluminescence dosimeter etc Barium aluminate BaAl2O4 doped with Ce is well known long lasting phosphor. This paper reports synthesis of BaAl2O4: Ce phosphor prepared by a simple combustion synthesis. The samples were characterized for the phase purity, chemical bonds and luminescent properties.

  3. Investigation of UV-emitting Gd(3+) -doped LiCaBO3 phosphor.

    PubMed

    Tamboli, Sumedha; Rajeswari, B; Dhoble, S J

    2016-03-01

    Incorporating the Gd(3+) rare earth ion in the LiCaBO3 host lattice resulted in narrow-band UV-B emission peaking at 315 nm, with excitation at 274 nm. The LiCaBO3 :Gd(3+) phosphor was synthesized via the solid-state diffusion method. The structural, morphological and luminescence properties of this phosphor were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. Electron paramagnetic resonance (EPR) characterization of the as-prepared phosphors is also reported here. XRD studies confirmed the crystal formation and phase purity of the prepared phosphors. A series of different dopant concentrations was synthesized and the concentration-quenching effect was studied. Critical energy transfer distance between activator ions was determined and the mechanism governing the concentration quenching is also reported in this paper. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26278621

  4. Chromatin nu bodies: isolation, subfractionation and physical characterization.

    PubMed Central

    Olins, A L; Carlson, R D; Wright, E B; Olins, D E

    1976-01-01

    Monomer chromatin subunit particles (nu1) have been isolated in gram quantities by large-scale zonal centrifugation of micrococcal nuclease digests of chicken erythrocyte nuclei. nu1 can be stored, apparently indefinitely, frozen in 0.2 mM EDTA (pH 7.0) at less than or equal to 25 degrees C. Aliquots of the stored monomers have been subfractionated by dialysis against 0.1 M KCl buffers into a soluble fraction containing equimolar amounts of H4, H3, H2A, H2B associated with a DNA fragment of approximately 130-140 nucleotide pairs, and a precipitated fraction containing all of the histones including H5 and H1 associated with DNA fragments. The total nu1 and the KCl-soluble fraction of nu1 have been examined by sedimentation, diffusion, sedimentation equilibrium ultracentrifugation, low-angle X-ray diffraction, and electron microscopy. Physical parameters from all of these techniques are presented and correlated in this study. Images PMID:1005117

  5. Reactor Physics Characterization of the HTR Module with UCO Fuel

    SciTech Connect

    Gerhard Strydom

    2011-01-01

    ABSTRACT The HTR Module [1] is a graphite-moderated, helium cooled pebble bed High Temperature Reactor (HTR) design that has been extensively used as a reference template for the former South African and current Chinese HTR [2] programs. This design utilized spherical fuel elements packed into a dynamic pebble bed, consisting of TRISO coated uranium oxide (UO2) fuel kernels with a U-235 enrichment of 7.8% and a Heavy Metal loading of 7 grams per pebble. The main objective of this study is to compare several important reactor physics and core design parameters for the HTR Module and an identical design utilizing UCO fuel kernels. Fuel kernels of this type are currently being tested in the Idaho National Laboratory’s (INL) Advanced Test Reactor (ATR) as part of the larger Next Generation Nuclear Plant (NGNP) project. The PEBBED-THERMIX [3] code, which was developed specifically for the analysis of pebble bed HTRs, was used to compare the coupled neutronic and thermal fluid performance of the two designs.

  6. Observation of asteroids with GRAVITY - Physical characterization of binary systems

    NASA Astrophysics Data System (ADS)

    Matter, A.; Delbo, M.; Carry, B.; Tanga, P.

    2014-12-01

    Density and internal structures are among the most important characteristics of asteroids, yet these properties are also some of the least known. For distant asteroids (in the Main Belt and beyond) these properties were up to now accessible only for the largest (>100 km in size) asteroids. Going to smaller and fainter asteroids can revolutionize our understanding because we will be sampling a new regime in physical properties. Here we discuss how ground-based optical interferometry with the GRAVITY instrument can be used to observe the motion of asteroid satellites to determine the mass of small binary systems. Following the expected sensitivity performances in K-band of GRAVITY, we present a sample of binary targets potentially observable in single-field mode. The feasibility of such observations will strongly be dependent on the ability of the control software of GRAVITY to track objects moving at high rate on the sky (differential motion ˜f 10 mas.s^{-1}). Although the dual-field mode could allow to increase the sample of small binary asteroids observable, it seems to be currently unfeasible given the high differential motion of asteroids.

  7. Characterization by spectroscopic Ellipsometry, the physical properties of silver nanoparticles.

    NASA Astrophysics Data System (ADS)

    Coanga, Jean-Maurice

    2013-04-01

    Physicists are able to change their minds through their experiments. I think it is time to go kick the curse and go further in research if we want a human future. I work in the Nano-Optics and Plasmonics research. I defined with ellipsomètrie the structure of new type of Nano particles of silver. It's same be act quickly to replace the old dirty leaded electronic-connexion chip and by the other hand to find a new way for the heath care of cancer disease by nanoparticles the next killers of bad cells. Silver nanoparticle layers are obtained by Spark Plasma Sintering are investigated as an alternative to lead alloy based material for solder joint in power mechatronics modules. These layers are characterized by mean of conventional techniques that is the dilatometry technique, the resistivity measurement through the van der Pauw method, and the flash laser technique. Furthermore, the nanoparticles of silver layer are deeply studied by UV-Visible spectroscopic ellipsometry. Spectroscopic angles parameters are determined in function of temperature and dielectric constants are deduced and analyzed through an optical model which takes into account a Drude and a Lorentz component within the Bruggeman effective medium approximation (EMA). The relaxation times and the electrical conductivity are plot in function of temperature. The obtained electrical conductivity give significant result in good agreement to those reported by four points electrical measurement method.

  8. Physics characterization and frequency stability of the pulsed rubidium maser

    SciTech Connect

    Godone, Aldo; Micalizio, Salvatore; Levi, Filippo; Calosso, Claudio

    2006-10-15

    In this paper we report the theoretical and experimental characterization of a pulsed optically pumped vapor-cell frequency standard based on the detection of the free-induction decay microwave signal. The features that make this standard similar to a pulsed passive maser are presented. In order to predict and optimize the frequency stability, thermal and shot noise sources are analyzed, as well as the conversions of the laser and microwave fluctuations into the output frequency. The experimental results obtained with a clock prototype based on {sup 87}Rb in buffer gas are compared with the theoretical predictions, showing the practical possibility to implement a frequency standard limited in the medium term only by thermal drift. The achieved frequency stability is {sigma}{sub y}({tau})=1.2x10{sup -12}{tau}{sup -1/2} for measurement times up to {tau}{approx_equal}10{sup 5} s. It represents one of the best results reported in literature for gas cell frequency standards and is compliant with the present day requirements for on board space applications.

  9. Intagliated phosphor screen image tube project

    NASA Technical Reports Server (NTRS)

    Hertzel, R. J.

    1982-01-01

    The production and evaluation of a magnetic focus image tube for astronomical photography that has an intagliated phosphor screen is described. The modulation transfer function of such a tube was measured by electronic means and by film tests, and the results compared with tubes of more conventional construction. The physical properties of the image tube and film combination, the analytical model of the optical interface, and the salient features of the intagliated screen tube are described. The results of electronic MTF tests of the intagliated image tube and of the densitometry of the tube and film test samples are presented. It is concluded that the intagliated screen is a help, but that the thickness of the photographic film is also important.

  10. Characterization of sheep lung lymph lipoproteins: chemical and physical properties

    SciTech Connect

    Forte, T.M.; Cross, C.E.; Gunther, R.A.; Kramer, G.C.

    1983-01-01

    The authors have determined the composition and distribution of plasma and lung lymph lipoproteins from unanesthetized ewes. Cholesterol, triglyceride, and phospholipid levels in lung lymph were 45%, 50%, and 50%, respectively, of those in plasma. Lipoproteins from both lymph and plasma were separated into two major fractions: d < 1.063 g/ml or LDL, and d 1.063-1.21 g/ml or HDL. HDL was the major lipoprotein species in the plasma and lymph. Gradients gel electrophoresis of HDL on 4-30% gels showed that, in lymph, HDL particles were shifted to larger sizes; in addition to a peak at 8.5 nm, which was similar to plasma HDL, there were two additional components of larger size, one at 9.2 nm and the other at 12 nm. Electron microscopy revealed that lymph HDL contained two new particles not seen in plasma: large, round particles, 13.6 nm diameter, and discoidal particles, 18.7 by 4.9 nm, long and short axis, respectively. Compositional analysis of lymph HDL revealed a relative enrichment in free cholesterol as well as an enrichment in apolipoprotein E. Lymph LDL on gradient gel electrophoresis was extremely heterogeneous. Several peaks were evident in the 23-30 nm size range (similar to plasma LDL), but a supplementary component at approximately 15-16 nm was also present. Whereas plasma LDL on electron microscopy contained only round particles 26 nm in diameter, lymph contained an additional, unusual particle which was close-packed, with square geometry, and was 15 nm in diameter. Changes in the physical and chemical properties of lung lymph lipoproteins suggest that these particles are metabolically modified.

  11. Treated and untreated rock dust: Quartz content and physical characterization.

    PubMed

    Soo, Jhy-Charm; Lee, Taekhee; Chisholm, William P; Farcas, Daniel; Schwegler-Berry, Diane; Harper, Martin

    2016-11-01

    Rock dusting is used to prevent secondary explosions in coal mines, but inhalation of rock dusts can be hazardous if the crystalline silica (e.g., quartz) content in the respirable fraction is high. The objective of this study is to assess the quartz content and physical characteristics of four selected rock dusts, consisting of limestone or marble in both treated (such as treatment with stearic acid or stearates) and untreated forms. Four selected rock dusts (an untreated and treated limestone and an untreated and treated marble) were aerosolized in an aerosol chamber. Respirable size-selective sampling was conducted along with particle size-segregated sampling using a Micro-Orifice Uniform Deposit Impactor. Fourier Transform Infrared spectroscopy and scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) analyses were used to determine quartz mass and particle morphology, respectively. Quartz percentage in the respirable dust fraction of untreated and treated forms of the limestone dust was significantly higher than in bulk samples, but since the bulk percentage was low the enrichment factor would not have resulted in any major change to conclusions regarding the contribution of respirable rock dust to the overall airborne quartz concentration. The quartz percentage in the marble dust (untreated and treated) was very low and the respirable fractions showed no enrichment. The spectra from SEM-EDX analysis for all materials were predominantly from calcium carbonate, clay, and gypsum particles. No free quartz particles were observed. The four rock dusts used in this study are representative of those presented for use in rock dusting, but the conclusions may not be applicable to all available materials. PMID:27314444

  12. Physical and chemical characterization of residential oil boiler emissions.

    PubMed

    Hays, Michael D; Beck, Lee; Barfield, Pamela; Lavrich, Richard J; Dong, Yuanji; Vander Wal, Randy L

    2008-04-01

    The toxicity of emissions from the combustion of home heating oil coupled with the regional proximity and seasonal use of residential oil boilers (ROB) is an important public health concern. Yet scant physical and chemical information about the emissions from this source is available for climate and air quality modeling and for improving our understanding of aerosol-related human health effects. The gas- and particle-phase emissions from an active ROB firing distillate fuel oil (commonly known as diesel fuel) were evaluated to address this deficiency. Ion chromatography of impactor samples showed that the ultrafine ROB aerosol emissions were approximately 45% (w/w) sulfate. Gas chromatography-mass spectrometry detected various n-alkanes at trace levels, sometimes in accumulation mode particles, and out of phase with the size distributions of aerosol mass and sulfate. The carbonaceous matter in the ROB aerosol was primarily light-adsorbing elemental carbon. Gas chromatography-atomic emission spectroscopy measured a previously unrecognized organosulfur compound group in the ROB aerosol emissions. High-resolution transmission electron microscopy of ROB soot indicated the presence of a highly ordered primary particle nanostructure embedded in larger aggregates. Organic gas emissions were measured using EPA Methods TO-15 and TO-11A. The ROB emitted volatile oxygenates (8 mg/(kg of oil burned)) and olefins (5 mg/(kg of oil burned)) mostly unrelated to the base fuel composition. In the final analysis, the ROB tested was a source of numerous hazardous air pollutants as defined in the Clean Air Act Amendments. Approximations conducted using emissions data from the ROB tests show relatively low contributions to a regional-level anthropogenic emissions inventory for volitile organic compounds, PM2.5, and SO2 mass. PMID:18504987

  13. Developing a phosphor-based health monitoring sensor suite for future spacecraft

    NASA Astrophysics Data System (ADS)

    Goedeke, S. M.; Hollerman, W. A.; Bergeron, N. P.; Allison, S. W.; Moore, R. J.

    2006-05-01

    The desire to explore the Moon and Mars by 2030 makes cost effective and low mass health monitoring sensors essential for spacecraft development. Parameters such as impact, temperature, and radiation fluence need to be measured in order to determine the health of a human occupied vehicle. A phosphor-based sensor offers one good approach to develop a robust health monitoring system. The authors have spent the last few years evaluating physical characteristics of zinc sulfide (ZnS) phosphors. These materials emit triboluminescence (TL) which is fluorescence produced as a result of an impact. Currently, two ZnS materials have been tested for impact response for velocities from 1 m/s to 6 km/s. These materials have also been calibrated for use as temperature sensors from room temperature to 350 °C. Finally, any sensor that is intended to function in space must be characterized for response to ionizing radiation. Research to date has included irradiating ZnS with 3 MeV protons and 20 keV electrons, which are likely components of the space radiation environment. Results have shown that that the fluorescence emission intensity decreases with radiation fluence. However, radiation induced damage can be annealed at small fluence levels. This annealing not only increased light intensity of the exposed sample from excitation but also TL excitation as well.

  14. Physical, chemical and biological characterization of six biochars produced for the remediation of contaminated sites.

    PubMed

    Denyes, Mackenzie J; Parisien, Michèle A; Rutter, Allison; Zeeb, Barbara A

    2014-01-01

    The physical and chemical properties of biochar vary based on feedstock sources and production conditions, making it possible to engineer biochars with specific functions (e.g. carbon sequestration, soil quality improvements, or contaminant sorption). In 2013, the International Biochar Initiative (IBI) made publically available their Standardized Product Definition and Product Testing Guidelines (Version 1.1) which set standards for physical and chemical characteristics for biochar. Six biochars made from three different feedstocks and at two temperatures were analyzed for characteristics related to their use as a soil amendment. The protocol describes analyses of the feedstocks and biochars and includes: cation exchange capacity (CEC), specific surface area (SSA), organic carbon (OC) and moisture percentage, pH, particle size distribution, and proximate and ultimate analysis. Also described in the protocol are the analyses of the feedstocks and biochars for contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals and mercury as well as nutrients (phosphorous, nitrite and nitrate and ammonium as nitrogen). The protocol also includes the biological testing procedures, earthworm avoidance and germination assays. Based on the quality assurance / quality control (QA/QC) results of blanks, duplicates, standards and reference materials, all methods were determined adequate for use with biochar and feedstock materials. All biochars and feedstocks were well within the criterion set by the IBI and there were little differences among biochars, except in the case of the biochar produced from construction waste materials. This biochar (referred to as Old biochar) was determined to have elevated levels of arsenic, chromium, copper, and lead, and failed the earthworm avoidance and germination assays. Based on these results, Old biochar would not be appropriate for use as a soil amendment for carbon sequestration, substrate quality

  15. Performance evaluation of a direct computed radiography system by means of physical characterization and contrast detail analysis

    NASA Astrophysics Data System (ADS)

    Rivetti, Stefano; Lanconelli, Nico; Bertolini, Marco; Borasi, Giovanni; Acchiappati, Domenico; Burani, Aldo

    2007-03-01

    The aim of this study is to determine the performance of a direct CR reader, named "FCR Velocity U Focused Phosphor (FP)". The system is based on a CsBr columnar structured crystal, and the system's read out is based on the "linescan technology" that employs a wide-view CCD. The system's physical performance was tested by means of a quantitative analysis, with calculation of the modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE). Image quality was assessed by performing a contrast-detail analysis. The results are compared with those obtained with the well known CR system Fuji FCR XG5000, and the new one Kodak DirectView CR 975. For all the measurements the standard radiation quality RQA-5 was used. The relationship between signal amplitude and entrance air kerma is logarithmic for all the systems and the response functions were used to linearize the images before the MTF (edge method) and NPS calculations. The contrast detail analysis has been achieved by using the well known CDRAD phantom and a customized software designed for automatic computation of the contrast-detail curves. The three systems present similar MTFs, whereas the Fuji Velocity U FP system, thanks to its greater efficiency, has a better behavior in terms of NNPS, especially at low frequencies. That allows the system based on columnar phosphor to provide a better DQE. CDRAD analysis basically confirms that the structured phosphor used in the Velocity system improves the visibility of some details. This is especially true for medium and large details.

  16. Spectral characterization of storage phosphor imaging plates

    SciTech Connect

    Deresch, A.; Jechow, M.; Gollwitzer, C.

    2014-02-18

    This work presents attenuation and sensitivity measurements of radiographic imaging plates (IPs) with quasimonoenergetic X-rays in the 8–60 kiloelectronvolt range. The measurements are used to validate theoretical predictions. A short overview of the theoretical model is given. The model can be used to describe the sensitivity of different detector types to a wide range of X-ray energies.

  17. Synthesis, characterization, and physical properties of 1D nanostructures

    NASA Astrophysics Data System (ADS)

    Marley, Peter Mchael

    framework is facilitated by the nanometer-sized dimensions of the materials, which leads to accommodation of strain without amorphization. The topotactic approach demonstrated here indicates not just novel intercalation chemistry accessible at nanoscale dimensions but also suggests a facile synthetic route to ternary vanadium oxide bronzes (MxV2O 5) exhibiting intriguing physical properties that range from electronic phase transitions to charge ordering and superconductivity.

  18. Method and apparatus for reading thermoluminescent phosphors

    DOEpatents

    Braunlich, Peter F.; Tetzlaff, Wolfgang

    1987-01-01

    An apparatus and method for rapidly reading thermoluminescent phosphors to determine the amount of luminescent energy stored therein. The stored luminescent energy is interpreted as a measure of the total exposure of the thermoluminescent phosphor to ionizing radiation. The thermoluminescent phosphor reading apparatus uses a laser to generate a laser beam. The laser beam power level is monitored by a laser power detector and controlled to maintain the power level nearly constant. A shutter or other laser beam interrupting means is used to control exposure of the thermoluminescent phosphor to the laser beam. The laser beam can be equalized using an optical equalizer so that the laser beam has an approximately uniform power density across the beam. The heated thermoluminescent phosphor emits a visible or otherwise detectable luminescent emission which is measured as an indication of the radiation exposure of the thermoluminescent phosphors. Also disclosed are preferred signal processing and control circuits.

  19. Phosphors with long-persistent green phosphorescence

    DOEpatents

    Yen, William M; Jia, Weiyi; Lu, Lizhu; Yuan, Huabiao

    2001-01-01

    This invention relates to phosphors including long-persistence green phosphors. Phosphors of the invention are represented by the general formula: M.sub.k Al.sub.2 O.sub.4 :2xEu.sup.2+,2yR.sup.3+ wherein k-1-2x-2y, x is a number ranging from about 0.0001 to about 0.05, y is a number ranging from about x to about 3x, M is an alkaline earth metal, and R.sup.3+ is one or more trivalent metal ions. Phosphors of this invention include powders, ceramics, single crystals and single crystal fibers. A method of manufacturing improved phosphors and a method of manufacturing single crystal phosphors are also provided.

  20. The effect of Tb{sup +3} on α-Sr{sub 2}P{sub 2}O{sub 7} phosphor for green LED phosphor application

    SciTech Connect

    Patel, Nimesh P. E-mail: mnsmsu@gmail.com; Srinivas, M.; Verma, Vishwnath; Modi, Dhaval

    2015-06-24

    A series of Tb{sup +3} activated α-Sr{sub 2}P{sub 2}O{sub 7} (Strontium Pyrophosphate) phosphors were synthesized by high temperature combustion synthesis method. The structural analysis has been done by x-ray diffraction and FTIR (Fourier Transform Infrared Spectrum). The results obtained in structural characterization indicate that the doping concentration did not affect the crystal phase and structure of the phosphors. X-ray diffraction pattern reveals that the all samples were consistence with the JCPDS card No. 24-1011. The phosphor was excited at 232 nm wavelength, very intense PL green emission peak have been observed at 545 nm. This illustrates, that the phosphors could be efficiently excited because of the charge transfer band of the host as well as the energy transfer process occurred between host (Sr{sub 2}P{sub 2}O{sub 7}) and activator (Tb{sup +3}). By increasing the doping concentration of Tb{sup +3}, the intensity of 545 nm emission peak has been increased predominantly and it suggest that the phosphor prepared has very good application in green LED phosphor.

  1. Primary chemical and physical characterization of acute toxic components in wastewaters

    SciTech Connect

    Svenson, A.; Linlin, Z.; Kaj, L. )

    1992-10-01

    A chemical and physical primary characterization work sheet was developed based on the Microtox test, a bacterial bioluminescence system used as a rapid estimate of acute aquatic toxic effects. Measurements of the variation in light reduction upon different pretreatments provided information about the chemical and physical properties of the main toxic component(s) in test wastewater samples. This primary characterization of a wastewater sample was performed within 1 day. Tests of pure toxic chemical compounds and wastewaters with known and unknown primary toxicants are presented. Outlines to the chemical analysis and identification of toxic components may be deduced from the primary characterization. The provisional characterization may also provide information on wastewater treatment techniques.

  2. Method of preparing a thermoluminescent phosphor

    DOEpatents

    Lasky, Jerome B.; Moran, Paul R.

    1979-01-01

    A thermoluminescent phosphor comprising LiF doped with boron and magnesium is produced by diffusion of boron into a conventional LiF phosphor doped with magnesium. Where the boron dopant is made to penetrate only the outer layer of the phosphor, it can be used to detect shallowly penetrating radiation such as tritium beta ays in the presence of a background of more penetrating radiation.

  3. Validation of the Physics Analysis used to Characterize the AGR-1 TRISO Fuel Irradiation Test

    SciTech Connect

    Sterbentz, James W.; Harp, Jason M.; Demkowicz, Paul A.; Hawkes, Grant L.; Chang, Gray S.

    2015-05-01

    The results of a detailed physics depletion calculation used to characterize the AGR-1 TRISO-coated particle fuel test irradiated in the Advanced Test Reactor (ATR) at the Idaho National Laboratory are compared to measured data for the purpose of validation. The particle fuel was irradiated for 13 ATR power cycles over three calendar years. The physics analysis predicts compact burnups ranging from 11.30-19.56% FIMA and cumulative neutron fast fluence from 2.21?4.39E+25 n/m2 under simulated high-temperature gas-cooled reactor conditions in the ATR. The physics depletion calculation can provide a full characterization of all 72 irradiated TRISO-coated particle compacts during and post-irradiation, so validation of this physics calculation was a top priority. The validation of the physics analysis was done through comparisons with available measured experimental data which included: 1) high-resolution gamma scans for compact activity and burnup, 2) mass spectrometry for compact burnup, 3) flux wires for cumulative fast fluence, and 4) mass spectrometry for individual actinide and fission product concentrations. The measured data are generally in very good agreement with the calculated results, and therefore provide an adequate validation of the physics analysis and the results used to characterize the irradiated AGR-1 TRISO fuel.

  4. Investigations of blue emitting phosphors for thermometry

    NASA Astrophysics Data System (ADS)

    Särner, Gustaf; Richter, Mattias; Aldén, Marcus

    2008-12-01

    Blue emitting phosphors are investigated and reported for possible use in thermometry. Currently reported thermographic phosphors in general have the drawback of long emission lifetimes obstructing the possibility to time gate for background discrimination. An additional problem is that many thermographic phosphors have emission in the red spectral region, making them vulnerable for black body radiation at high temperatures. This work reports the temperature sensitivity for nine phosphors considered suitable for accurate temperature measurements in harsh conditions both in single points and in two dimensions (2D).

  5. Bluish-green color emitting Ba2Si3O8:Eu2+ ceramic phosphors for white light-emitting diodes.

    PubMed

    Xiao, F; Xue, Y N; Zhang, Q Y

    2009-10-15

    This paper reports on the structural and optical properties of Eu(2+) activated Ba(2)Si(3)O(8) ceramic phosphors synthesized by a sol-gel method. The ceramic phosphors have been characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and fluorescence measurements. The structural characterization results suggest that the as-prepared phosphors are of single phase monoclinic Ba(2)Si(3)O(8) with rod-like morphology. A broad excitation band ranging from 300 to 410 nm matches well with the ultraviolet (UV) radiation of light-emitting diodes (LEDs). Upon 380 nm UV light excitation, these phosphors emit bluish-green emission centered at 500 nm with color coordination (x=0.25, y=0.40). All the obtained results indicate that the Ba(2)Si(3)O(8):Eu(2+) ceramic phosphors are promising bluish-green candidates for the phosphor-converted white LEDs. PMID:19720559

  6. 46 CFR 151.50-23 - Phosphoric acid.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... phosphoric acid, and super phosphoric acid. (b) Phosphoric acid may be carried in either gravity or pressure... gravity type cargo tanks. (d) Cargo piping, including valves, fittings, and flanges where exposed to...

  7. Synthesis and luminescence properties of KSrPO4:Eu2+ phosphor for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Palan, C. B.; Bajaj, N. S.; Omanwar, S. K.

    2016-05-01

    The KSrPO4:Eu phosphor was synthesized via solid state method. The structural and morphological characterizations were done through XRD (X-ray diffraction) and SEM (Scanning Electronic Microscope). Additionally, the photoluminescence (PL), thermoluminescence (TL) and optically Stimulated luminescence (OSL) properties of powder KSrPO4:Eu were studied. The PL spectra show blue emission under near UV excitation. It was advocated that KSrPO4:Eu phosphor not only show OSL sensitivity (0.47 times) but also gives faster decay in OSL signals than that of Al2O3:C (BARC) phosphor. The TL glow curve consist of two shoulder peaks and the kinetics parameters such as activation energy and frequency factors were determined by using peak shape method and also photoionization cross-sections of prepared phosphor was calculated. The radiation dosimetry properties such as minimum detectable dose (MDD), dose response and reusability were reported.

  8. Characterization Of Environmentally Relevant Chemical And Physical Properties Of Silver Nano-Particles

    EPA Science Inventory

    Understanding and predicting the fate and transport of nano-materials in the environment requires a detailed characterization of the chemical and physical properties that control fate and transport. In the current study, we have evaluated the surface charge, aggregation potentia...

  9. MICROSENSORS FOR IN-SITU CHEMICAL, PHYSICAL, AND RADIOLOGICAL CHARACTERIZATION OF MIXED WASTE

    EPA Science Inventory

    A widespread need exists for portable, real-time, in-situ chemical, physical, and radiological sensors for the characterization and monitoring of mixed waste, ground water, contaminated soil and process streams. The applications range from monitoring plume containment and the res...

  10. MICROSENSORS FOR IN-SITE CHEMICAL, PHYSICAL, AND RADIOLOGICAL CHARACTERIZATION OF MIXED WASTE

    EPA Science Inventory

    A widespread need exists for portable, real-time, in-situ chemical, physical, and radiological sensors in characterization of mixed waste, groundwater, contaminated soils and process streams. None of the currently available technologies offer a clear path to the development of se...

  11. CHARACTERIZATION OF ACTIVATED CARBONS' PHYSICAL AND CHEMICAL PROPERTIES IN RELATION TO THEIR MERCURY ADSORPTION

    EPA Science Inventory

    The paper gives results of a characterization of the physical and chemical properties of the activated carbons used for elemental mercury (Hgo) adsorption, in order to understand the role of oxygen surface functional groups on the mechanism of Hgo adsorption by activated carbons....

  12. Radiological, physical, and chemical characterization of transuranic wastes stored at the Idaho National Engineering Laboratory

    SciTech Connect

    Apel, M.L.; Becker, G.K.; Ragan, Z.K.; Frasure, J.; Raivo, B.D.; Gale, L.G.; Pace, D.P.

    1994-03-01

    This document provides radiological, physical and chemical characterization data for transuranic radioactive wastes and transuranic radioactive and hazardous (i.e., mixed) wastes stored at the Idaho National Engineering Laboratory and considered for treatment under the Private Sector Participation Initiative Program (PSPI). Waste characterization data are provided in the form of INEL Waste Profile Sheets. These documents provide, for each content code, information on waste identification, waste description, waste storage configuration, physical/chemical waste composition, radionuclide and associated alpha activity waste characterization data, and hazardous constituents present in the waste. Information is provided for 139 waste streams which represent an estimated total volume of 39,380{sup 3} corresponding to a total mass of approximately 19,000,000 kg. In addition, considerable information concerning alpha, beta, gamma, and neutron source term data specific to Rocky Flats Plant generated waste forms stored at the INEL are provided to assist in facility design specification.

  13. Effect of Flux on the Formation of Sr2CeO4 Phosphor Doped with Er

    NASA Astrophysics Data System (ADS)

    Murthy, K. V. R.; Rao, B. Nageswara; Rajasekhar, B. N.; Kumar, B. Walter Ratna; Suresh, K.; Rao, B. Subba

    Photoluminescence (PL) of the Sr2CeO4 phosphor, doped with Erbium with different concentrations (0.01, 0.1, 0.5 and 1 mol %) is described in the present paper. The phosphors were synthesized using the standard solid state reaction technique using urea and citric acid as fluxes. The prepared phosphors are characterized using X-ray diffraction (XRD), and SEM. PL emission of undoped Sr2CeO4 phosphor and doped with various concentrations of Er was studied. The observed PL emission is at 470 nm followed by the primary Er emissions with good intensity at 527, 536, 550, 559 and 567 nm. The present phosphor may be a good candidate for compact fluorescent lamps for green emission.

  14. Characterizing pedagogical practices of university physics students in informal learning environments

    NASA Astrophysics Data System (ADS)

    Hinko, Kathleen A.; Madigan, Peter; Miller, Eric; Finkelstein, Noah D.

    2016-06-01

    [This paper is part of the Focused Collection on Preparing and Supporting University Physics Educators.] University educators (UEs) have a long history of teaching physics not only in formal classroom settings but also in informal outreach environments. The pedagogical practices of UEs in informal physics teaching have not been widely studied, and they may provide insight into formal practices and preparation. We investigate the interactions between UEs and children in an afterschool physics program facilitated by university physics students from the University of Colorado Boulder. In this program, physics undergraduates, graduate students, and postdoctoral researchers work with K-8 children on hands-on physics activities on a weekly basis over the course of a semester. We use an activity theoretic framework as a tool to examine situational aspects of individuals' behavior in the complex structure of the afterschool program. Using this framework, we analyze video of UE-child interactions and identify three main pedagogical modalities that UEs display during activities: instruction, consultation, and participation modes. These modes are characterized by certain language, physical location, and objectives that establish differences in UE-child roles and division of labor. Based on this analysis, we discuss implications for promoting pedagogical strategies through purposeful curriculum development and university educator preparation.

  15. Physical characterization and profiling of airway epithelial derived exosomes using light scattering.

    PubMed

    Kesimer, Mehmet; Gupta, Richa

    2015-10-01

    Exosomes and other extracellular vesicles have been gaining interest during the last decade due to their emerging role in biology and, disease pathogenesis and their biomarker potential. Almost all published research related to exosomes and other extracellular vesicles include some form of physical characterization. Therefore, these vesicles should be precisely profiled and characterized physically before studying their biological role as intercellular messengers, biomarkers or therapeutic tools. Using a combination of light scattering techniques, including dynamic light scattering (DLS) and multi-angle laser light scattering combined with size exclusion separation (SEC-MALLS), we physically characterized and compared distinct extracellular vesicles derived from the apical secretions of two different cultured airway epithelial cells. The results indicated that epithelial cells release vesicles with distinct physical properties and sizes. Human primary tracheobronchial cell culture (HTBE) derived vesicles have a hydrodynamic radius (Rh) of approximately 340 nm while their radius of gyration (Rg) is approximately 200 nm. Electron microscopy analysis, however, revealed that their spherical component is 40-100 nm in size, and they carry filamentous, entangled membrane mucins on their surface that increases their overall radius. The mucin decoration on the surface defines their size and charge as measured using light scattering techniques. Their surface properties mirror the properties of the cells from which they are derived. This may provide a unique tool for researchers to elucidate the unanswered questions in normal airway biology and innate and adaptive defense, including the remodeling of airways during inflammation, tumorigenesis and metastasis. PMID:25823850

  16. Characterizing Pedagogical Practices of University Physics Students in Informal Learning Environments

    NASA Astrophysics Data System (ADS)

    Hinko, Kathleen

    2016-03-01

    University educators (UEs) have a long history of teaching physics not only in formal classroom settings but also in informal outreach environments. The pedagogical practices of UEs in informal physics teaching have not been widely studied, and they may provide insight into formal practices and preparation. We investigate the interactions between UEs and children in an afterschool physics program facilitated by university physics students from the University of Colorado Boulder. In this program, physics undergraduates, graduate students and post-doctoral researchers work with K-8 children on hands-on physics activities on a weekly basis over the course of a semester. We use an Activity Theoretic framework as a tool to examine situational aspects of individuals' behavior in the complex structure of the afterschool program. Using this framework, we analyze video of UE-child interactions and identify three main pedagogical modalities that UEs display during activities: Instruction, Consultation and Participation modes. These modes are characterized by certain language, physical location, and objectives that establish differences in UE-child roles and division of labor. Based on this analysis, we discuss implications for promoting pedagogical strategies through purposeful curriculum development and university educator preparation.

  17. Electronic structure descriptor for the discovery of narrow-band red-emitting phosphors

    DOE PAGESBeta

    Wang, Zhenbin; Chu, Iek -Heng; Zhou, Fei; Ong, Shyue Ping

    2016-05-09

    Narrow-band red-emitting phosphors are a critical component of phosphor-converted light-emitting diodes for highly efficient illumination-grade lighting. In this work, we report the discovery of a quantitative descriptor for narrow-band Eu2+-activated emission identified through a comparison of the electronic structures of known narrow-band and broad-band phosphors. We find that a narrow emission bandwidth is characterized by a large splitting of more than 0.1 eV between the two highest Eu2+ 4f7 bands. By incorporating this descriptor in a high-throughput first-principles screening of 2259 nitride compounds, we identify five promising new nitride hosts for Eu2+-activated red-emitting phosphors that are predicted to exhibit goodmore » chemical stability, thermal quenching resistance, and quantum efficiency, as well as narrow-band emission. Lastly, our findings provide important insights into the emission characteristics of rare-earth activators in phosphor hosts and a general strategy to the discovery of phosphors with a desired emission peak and bandwidth.« less

  18. The effect of phosphor persistence on image quality in digital x-ray scanning systems.

    PubMed

    Mainprize, J G; Yaffe, M J

    1998-12-01

    A digital x-ray scanning system offers several advantages over conventional film-screen systems. However, there are sources of image degradation resulting from the scanning motion, such as motion blur due to the temporal response of the phosphor. This mechanism produces an asymmetrical blur, requiring the use of the complex optical transfer function (OTF) rather than the normal modulation transfer function (MTF) for correct characterization of image resolution. The luminescence response of eight phosphors was measured under pulsed x-ray excitation. A weighted exponential model was used to represent the primary luminescence. The dominant luminescence life-times ranged from 2.7 microseconds for Gd2O2S:Pr to 558 microseconds for Gd2O2S:Tb. The long term response was also measured, monitoring significant increases in a slow form of luminescence known as afterglow. Afterglow was modeled by an inverse power law equation. Afterglow was found to be strong in two of the phosphors studied (ZnCdS:Ag and YTaO4). In selecting a phosphor for a scanning system, it must satisfy several criteria, including a fast temporal response. Thus, a phosphor like Gd2O2S:Tb, which has a slow luminescence, but otherwise excellent imaging properties, may not be as useful as a more rapid phosphor like CsI:Tl. PMID:9874838

  19. Physical Characterization of Solid-Liquid Slurries at High Weight Fractions Using Optical and Ultrasonic Methods

    SciTech Connect

    Burgess, L.W.; Brodsky, A.M.; Panetta P.D.

    2005-12-22

    Remediation of highly radioactive waste is a major technical and programmatic challenge for the DOE. Rapid, on-line physical characterization of highly concentrated slurries is required for the safe and efficient remediation of 90 million gallons of high level radioactive waste (HLW), sodium bearing waste, and mixed waste. The research presented here, describes a collaborative effort between Pacific Northwest National Laboratory (PNNL) and the University of Washington (UW) to directly address the need for rapid on-line characterization of the physical properties of HLW slurries during all phases of the remediation process, from in-tank characterization of sediments to monitoring of the concentration, particle size, and degree of agglomeration and gelation of slurries during transport. Near-surface characterization of the slurry flow in the particle size range from nanometer to micrometer is examined using optical low coherence reflectometry. Volumetric characterization at depths in the slurry flow, up to several centimeters in the particle size range from the micrometer to millimeter, is realized by utilizing ultrasonic backscatter and diffuses fields. One of the strengths, the teaming up of significant talents in both experimental and theoretical optics and in ultrasonics, provides a synergistic approach to integrate these complimentary techniques. One of the benefits of this combined approach is the physical characterization of HLW over a concentration and particle size range that is broader than can be achieved with today's technology. This will avoid a costly increase in waste stream volume due to excess dilution, and will lessen chance of plugging pipes that could shut down expensive processing lines.

  20. Physics and gel electrophoresis: using terminal velocity to characterize molecular weight

    NASA Astrophysics Data System (ADS)

    Viney, Christopher; Fenton, Richard A.

    1998-11-01

    Protein molecular weights are commonly characterized by gel electrophoresis. Biology textbooks typically quote an empirical, approximate relationship between migration rate and molecular weight, relying on an inappropriately simplistic model of spherical particles travelling at their terminal velocity through a viscous medium. We show how the model can be modified to derive a physically realistic equation that relates migration rate and molecular weight, and that mirrors experimentally observed behaviour. We suggest that gel electrophoresis provides an interesting interdisciplinary context in which to exercise several basic principles that are encountered through introductory physics courses. Finally, we provide additional examples of practical situations where the concept of terminal velocity can be elaborated and applied.

  1. Optical Microscopy Characterization for Borehole U-15n#12 in Support of NCNS Source Physics Experiment

    SciTech Connect

    Wilson, Jennifer E.; Sussman, Aviva Joy

    2015-05-22

    Optical microscopy characterization of thin sections from corehole U-15n#12 is part of a larger material characterization effort for the Source Physics Experiment (SPE). The SPE program was conducted in Nevada with a series of explosive tests designed to study the generation and propagation of seismic waves inside Stock quartz monzonite. Optical microscopy analysis includes the following: 1) imaging of full thin sections (scans and mosaic maps); 2) high magnification imaging of petrographic texture (grain size, foliations, fractures, etc.); and 3) measurement of microfracture density.

  2. Effect of particle size and dopant concentration on photophysical properties of Eu3+-doped rare earth oxysulphide phosphor coatings.

    PubMed

    Chakradhar, R P S; Basu, Bharathibai J; Lakshmi, R V

    2011-02-01

    Europium-doped rare-earth oxysulphides (red phosphors) are often used as reference luminophore in pyrene-based pressure sensor coatings for aerodynamic applications. Different red phosphor samples were characterized for their particle size, chemical composition, photoluminescent properties and temperature sensitivity. The red phosphor samples were characterized using energy-dispersive X-ray spectroscopy (EDX) for elemental analysis and scanning electron microscopy (SEM) for morphology and particle size measurement. The particle size was in the range of 1.5-5.7 μm with morphology of hexagonal or spherical shape. It was found that phosphor with higher europium content exhibited higher luminescent emission intensity. The phosphor coatings were prepared by spraying a dispersion of the material in silicone resin. Smooth coatings were obtained by using phosphor samples with smaller particle size. Upon 334 nm excitation, the coatings showed characteristic luminescence 5D0→7FJ (J=0, 1, 2, 3, 4) of the Eu3+ ions. The electronic transition located at 626 nm (5D0→7F2) of Eu3+ ions was stronger than the magnetic dipole transition located at 595 nm (5D0→7F1). Luminescence decay curves obeyed double exponential behaviour. The phosphor samples showed temperature sensitivity of -0.012 to -0.168%/°C in the temperature range of 25-50 °C. PMID:21215689

  3. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Special requirements for phosphoric acid. 153.558... Equipment Special Requirements § 153.558 Special requirements for phosphoric acid. A phosphoric acid... phosphoric acid tanks by the Commandant (CG-ENG); or (c) Made of a stainless steel that resists corrosion...

  4. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Special requirements for phosphoric acid. 153.558... Equipment Special Requirements § 153.558 Special requirements for phosphoric acid. A phosphoric acid... phosphoric acid tanks by the Commandant (CG-ENG); or (c) Made of a stainless steel that resists corrosion...

  5. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Special requirements for phosphoric acid. 153.558... Equipment Special Requirements § 153.558 Special requirements for phosphoric acid. A phosphoric acid... phosphoric acid tanks by the Commandant (CG-522); or (c) Made of a stainless steel that resists corrosion...

  6. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Special requirements for phosphoric acid. 153.558... Equipment Special Requirements § 153.558 Special requirements for phosphoric acid. A phosphoric acid... phosphoric acid tanks by the Commandant (CG-522); or (c) Made of a stainless steel that resists corrosion...

  7. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Special requirements for phosphoric acid. 153.558... Equipment Special Requirements § 153.558 Special requirements for phosphoric acid. A phosphoric acid... phosphoric acid tanks by the Commandant (CG-ENG); or (c) Made of a stainless steel that resists corrosion...

  8. 46 CFR 151.50-23 - Phosphoric acid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Phosphoric acid. 151.50-23 Section 151.50-23 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-23 Phosphoric acid. (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions...

  9. 46 CFR 151.50-23 - Phosphoric acid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Phosphoric acid. 151.50-23 Section 151.50-23 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-23 Phosphoric acid. (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions...

  10. 46 CFR 151.50-23 - Phosphoric acid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Phosphoric acid. 151.50-23 Section 151.50-23 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-23 Phosphoric acid. (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions...

  11. 46 CFR 151.50-23 - Phosphoric acid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Phosphoric acid. 151.50-23 Section 151.50-23 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-23 Phosphoric acid. (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions...

  12. X-Ray and Ultraviolet Luminescence of Li 3Ta 1- xNb xO 4 Prepared by Flux Synthesis and Characterization of a New High Efficiency X-Ray Phosphor

    NASA Astrophysics Data System (ADS)

    Miao, C. R.; Torardi, C. C.

    1999-06-01

    The phase development and luminescence properties, under both X-ray and ultraviolet excitation, of the lithium orthotantalate-lithium orthoniobate system, Li3Ta1-xNbxO4 for x=0 to 1, were examined. Using a flux synthesis technique, it was found that the levels of Nb-doping in monoclinic Li3TaO4 and of Ta-doping in cubic Li3NbO4 are higher than previously reported. Under 30 kVp molybdenum X-ray excitation, Li3Ta1-xNb4O4 is an efficient blue-emitting phosphor with broadband emission, peaking in the range of 390 to 435 nm. For x=0 to 0.1, the overall luminescence efficiency is comparable to, or better than, a commercial calcium tungstate, CaWO4, Hi-Plus material. The composition Li3Ta0.995Nb0.005O4 demonstrates an overall luminescence efficiency that makes this phosphor 45% brighter than CaWO4 Hi-Plus, thereby making it a potentially attractive candidate for use in medical diagnostic imaging systems. Under ultraviolet excitation, broadband blue emission is also observed. For all the Li3Ta1-xNbxO4 (x>0) solid solutions, the emission peak maximums agree well with those seen under X-ray excitation and are the result of Nb5+ emission.

  13. Methodology for detecting residual phosphoric acid in polybenzoxazole fibers.

    PubMed

    Park, Eun Su; Sieber, John; Guttman, Charles; Rice, Kirk; Flynn, Kathleen; Watson, Stephanie; Holmes, Gale

    2009-12-01

    Because of the premature failure of in-service soft-body armor containing the ballistic fiber poly[(benzo-[1,2-d:5,4-d']-benzoxazole-2,6-diyl)-1,4-phenylene] (PBO), the Office of Law Enforcement Standards (OLES) at the National Institute of Standards and Technology (NIST) initiated a research program to investigate the reasons for this failure and to develop testing methodologies and protocols to ensure that these types of failures do not reoccur. In a report that focused on the stability of the benzoxazole ring that is characteristic of PBO fibers, Holmes, G. A.; Rice, K.; Snyder, C. R. J. Mater. Sci. 2006, 41, 4105-4116, showed that the benzoxazole ring was susceptible to hydrolytic degradation under acid conditions. Because of the processing conditions for the fibers, it is suspected by many researchers that residual phosphoric acid may cause degradation of the benzoxazole ring resulting in a reduction of ballistic performance. Prior to this work, no definitive data have indicated the presence of phosphoric acid since the residual phosphorus is not easily extracted and the processed fibers are known to incorporate phosphorus containing processing aids. Methods to efficiently extract phosphorus from PBO are described in this article. Further, characterization determined that the majority of the extractable phosphorus in PBO was attributed to the octyldecyl phosphate processing aid with some phosphoric acid being detected. Analysis by matrix assisted laser desorption ionization of model PBO oligomers indicates that the nonextractable phosphorus is attached to the PBO polymer chain as a monoaryl phosphate ester. The response of model aryl phosphates to NaOH exposure indicates that monoaryl phosphate ester is stable to NaOH washes used in the manufacturing process to neutralize the phosphoric acid reaction medium and to extract residual phosphorus impurities. PMID:19899783

  14. Skin Temperature Recording with Phosphors

    PubMed Central

    Lawson, Ray N.; Alt, Leslie L.

    1965-01-01

    New knowledge of temperature irregularities associated with various disease states has resulted in increasing interest in the recording of heat radiation from the human body. Infrared radiation from the skin is a surface phenomenon and the amount of such radiation increases with temperature. Previous recording techniques have been not only crude but difficult and expensive. An unconventional thermal imaging system is described which gives superior temperature patterns and is also simpler and cheaper than any of the other available procedures. This system is based on the employment of thermally sensitive phosphors which glow when exposed to ultraviolet illumination, in inverse proportion to the underlying temperature. The thermal image can be directly observed or more critically analyzed and photographed on a simple closed-circuit television monitor. ImagesFig. 3Fig. 3Fig. 4Fig. 5Fig. 6 PMID:14270208

  15. Initial Characterization of Colombian High School Physics Teachers' Pedagogical Content Knowledge on Electric Fields

    NASA Astrophysics Data System (ADS)

    Melo-Niño, Lina Viviana; Cañada, Florentina; Mellado, Vicente

    2015-09-01

    We explore the initial characterization of the pedagogical content knowledge of four, in-service, Colombian pre-university secondary education physics teachers on the concept of electric field. Two of them teach the content in English as a second language. The aim of the study was to obtain an image of the participants' teaching of electric field and the inherent complexities that go with that. The results revealed that factors which involved their personal educational models, such as, how they interpret their school's curriculum, the relationship they see between physics and mathematics, the most effective strategies for teaching physics, and the time they have available to develop the topic played a significant role. The teachers considered it essential to establish new strategies that would motivate the pupils by helping them visualize the electric field.

  16. Phosphorous-Containing Polymers for Regenerative Medicine

    PubMed Central

    Watson, Brendan M.; Kasper, F. Kurtis; Mikos, Antonios G.

    2014-01-01

    Disease and injury have resulted in a large, unmet need for functional tissue replacements. Polymeric scaffolds can be used to deliver cells and bioactive signals to address this need for regenerating damaged tissue. Phosphorous-containing polymers have been implemented to improve and accelerate the formation of native tissue both by mimicking the native role of phosphorous groups in the body and by attachment of other bioactive molecules. This manuscript reviews the synthesis, properties, and performance of phosphorous-containing polymers that can be useful in regenerative medicine applications. PMID:24565855

  17. Radioactivity measurements using storage phosphor technology

    SciTech Connect

    Cheng, Y.T.; Hwang, J.; Hutchinson, M.R.

    1995-10-01

    We propose to apply a recently developed charged particle radiation imaging concept in bio-medical research for fast, cost-effective characterization of radionuclides in contaminated sites and environmental samples. This concept utilizes sensors with storage photostimulable phosphor (SPP) technology as radiation detectors. They exhibit high sensitivity for all types of radiation and the response is linear over a wide dynamic range (>10{sup 5}), essential for quantitative analysis. These new sensors have an Active area of up to 35 cm x 43 cm in size and a spatial resolution as fine as 50 {mu}m. They offer considerable promise as large area detectors for fast characterization of radionuclides with an added ability to locate and identify hot spots. Tests with SPP sensors have found that a single alpha particle effect can be observed and an alpha field of 100 dpm/100 cm{sup 2} or a beta activity of 0.1 dpm/mm{sup 2} or gamma radiation of few {mu}R/hr can all be measured in minutes. Radioactive isotopes can further be identified by energy discrimination which is accomplished by placing different thicknesses of filter material in front of the sensor plate. For areas with possible neutron contamination, the sensors can be coupled to a neutron to charged particle converter screen, such as dysprosium foil to detect neutrons. Our study has shown that this approach can detect a neutron flux of 1 n/cm{sup 2}s or lower, again with only minutes of exposure time. The utilization of these new sensors can significantly reduce the time and cost required for many site characterization and environmental monitoring tasks. The {open_quotes}exposure{close_quotes} time for mapping radioactivity in an environmental sample may be in terms of minutes and offer a positional resolution not obtainable with presently used counting equipment. The resultant digital image will lend itself to ready analysis.

  18. Phosphors for solid-state lighting: New systems, deeper understanding

    NASA Astrophysics Data System (ADS)

    Denault, Kristin Ashley

    We explore the structure-composition-property relationships in phosphor materials using a multitude of structural and optical characterization methods including high resolution synchrotron X-ray and neutron powder diffraction and total scattering, low-temperature heat capacity, temperature- and time-resolved photoluminescence, and density functional theory calculations. We describe the development of several new phosphor compositions and provide an in-depth description of the structural and optical properties. We show structural origins of improved thermal performance of photoluminescence and methods for determining structural rigidity in phosphor hosts that may lead to improved luminescent properties. New white light generation strategies are also explored. We begin by presenting the development of a green-yellow emitting oxyfluoride solid-solution phosphor Sr2Ba(AlO4F)1- x(SiO5)x:Ce3+. An examination of the host lattice, and the local structure around the Ce3+ activator ions points to how chemical substitutions play a crucial role in tuning the optical properties of the phosphor. The emission wavelength can be tuned from green to yellow by tuning the composition, x. Photoluminescent quantum yield is determined to be 70+/-5% for some of the examples in the series with excellent thermal properties. Phosphor-converted LED devices are fabricated using an InGaN LED and are shown to exhibit high color rendering white light. Next, we identify two new phosphor solid-solution systems, (Ba1- xSrx)9 Sc2Si6O24:Ce3+,Li+ and Ba9(Y1-ySc y)2Si6O24:Ce3+. The substitution of Sr for Ba in (Ba1-xSrx ) 9Sc2Si6O24:Ce 3+,Li + results in a decrease of the alkaline earth-oxygen bond distances at all three crystallographic sites, leading to changes in optical properties. The room temperature photoluminescent measurements show the structure has three excitation peaks corresponding to Ce3+ occupying the three independent alkaline earth sites. The emission of (Ba 1- xSrx) 9Sc2Si 6O24:Ce3

  19. Microbiology and atmospheric processes: biological, physical and chemical characterization of aerosol particles

    NASA Astrophysics Data System (ADS)

    Georgakopoulos, D. G.; Després, V.; Fröhlich-Nowoisky, J.; Psenner, R.; Ariya, P. A.; Pósfai, M.; Ahern, H. E.; Moffett, B. F.; Hill, T. C. J.

    2008-04-01

    The interest in bioaerosols has traditionally been linked to health hazards for humans, animals and plants. However, several components of bioaerosols exhibit physical properties of great significance for cloud processes, such as ice nucleation and cloud condensation. To gain a better understanding of their influence on climate, it is therefore important to determine the composition, concentration, seasonal fluctuation, regional diversity and evolution of bioaerosols. In this paper, we will review briefly the existing techniques for detection, quantification, physical and chemical analysis of biological particles, attempting to bridge physical, chemical and biological methods for analysis of biological particles and integrate them with aerosol sampling techniques. We will also explore some emerging spectroscopy techniques for bulk and single-particle analysis that have potential for in-situ physical and chemical analysis. Lastly, we will outline open questions and further desired capabilities (e.g., in-situ, sensitive, both broad and selective, on-line, time-resolved, rapid, versatile, cost-effective techniques) required prior to comprehensive understanding of chemical and physical characterization of bioaerosols.

  20. Microbiology and atmospheric processes: biological, physical and chemical characterization of aerosol particles

    NASA Astrophysics Data System (ADS)

    Georgakopoulos, D. G.; Després, V.; Fröhlich-Nowoisky, J.; Psenner, R.; Ariya, P. A.; Pósfai, M.; Ahern, H. E.; Moffett, B. F.; Hill, T. C. J.

    2009-04-01

    The interest in bioaerosols has traditionally been linked to health hazards for humans, animals and plants. However, several components of bioaerosols exhibit physical properties of great significance for cloud processes, such as ice nucleation and cloud condensation. To gain a better understanding of their influence on climate, it is therefore important to determine the composition, concentration, seasonal fluctuation, regional diversity and evolution of bioaerosols. In this paper, we will review briefly the existing techniques for detection, quantification, physical and chemical analysis of biological particles, attempting to bridge physical, chemical and biological methods for analysis of biological particles and integrate them with aerosol sampling techniques. We will also explore some emerging spectroscopy techniques for bulk and single-particle analysis that have potential for in-situ physical and chemical analysis. Lastly, we will outline open questions and further desired capabilities (e.g., in-situ, sensitive, both broad and selective, on-line, time-resolved, rapid, versatile, cost-effective techniques) required prior to comprehensive understanding of chemical and physical characterization of bioaerosols.

  1. A high sensitive phosphor for dosimetric applications

    NASA Astrophysics Data System (ADS)

    Kore, Bhushan P.; Dhoble, N. S.; Lochab, S. P.; Dhoble, S. J.

    2015-06-01

    In this study a novel TL phosphor CaMg3(SO4)4:Dy3+ was prepared by acid distillation method. The TL response of this phosphor towards γ-rays and carbon ion beam was tested. Good dosimetric glow curve was observed which is stable against both the type of radiations. The CaMg3(SO4)4:Dy3+ phosphor doped with 0.2 mol% of Dy3+, irradiated with γ-ray shows nearly equal sensitivity to that of commercially available CaSO4:Dy TLD phosphor whereas 3.5 times more sensitivity than CaSO4:Dy, when irradiated with carbon ion beam. The change in glow peak intensities and glow peak temperature with variation in irradiation species and energy of ion beam is discussed here. The effect of these on trapping parameters is also illustrated.

  2. Comparison analysis on the properties of the phosphor film according to the various composition ratio of phosphor slurry

    NASA Astrophysics Data System (ADS)

    Park, Jeong Yeon; Lee, Jeong Won; Heo, Young Moo; Won, Si Tae; Yoon, Gil Sang

    2016-03-01

    The conventional method of making a phosphor layer on the LED package by using a dispensing method is difficult to implement the specific color coordinate, color temperature and optical efficiency because the thickness of the phosphor layer is non-uniform due to precipitation of the phosphor. Besides, the dispensing method consume a large amount of phosphor and silicone to fill the LED package. Thus, studies that manufacture phosphor layer with a uniform thickness such as spray coating, screen printing, electrophoresis are active recently. The purpose of this study is to perform the basic research about the change of the characteristics of phosphor film that is molded with uniform thickness using the phosphor slurry according to various silicone resin and phosphor composition ratio. It is expected to be used as useful information for the fabricating properties when production environment of phosphor layer is changed dispensing method into phosphor film fabrication. In the experiment, it was selected three kinds of methyl-phenyl silicone based resin as the phosphor slurry constituents, and mixed with phosphor various amount of 20 ˜ 60wt% content per one silicone resin. Using this mixed phosphor slurry, it was molded the phosphor film with 300 μm thickness and analyzed the mechanical properties and optical properties of the phosphor film. Finally, the results of this study are presented below: (a) As the phenyl group content is increased, the total heat of reaction need to cure the silicone resin is decrease, and also lower the durometer hardness of the phosphor sheet. On the other hand, it was confirmed that there is no relationship between the phenyl group content in the phosphor film and optical characteristics of the phosphor film. (b) If the amount of the phosphor within the film are increased, then the values of shore hardness and CIE color coordinates are increased gradually but the value of CIE color temperature is decreased gradually in case of being

  3. Stabilizing platinum in phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Remick, R. J.

    1982-01-01

    Platinum sintering on phosphoric acid fuel cell cathodes is discussed. The cathode of the phosphoric acid fuel cell uses a high surface area platinum catalyst dispersed on a conductive carbon support to minimize both cathode polarization and fabrication costs. During operation, however, the active surface area of these electrodes decreases, which in turn leads to decreased cell performance. This loss of active surface area is a major factor in the degradation of fuel cell performance over time.

  4. Enhancement of the photoluminescence and long afterglow properties of Sr2MgSi2O7:Eu(2+) phosphor by Dy(3+) co-doping.

    PubMed

    Sahu, Ishwar Prasad; Bisen, D P; Brahme, Nameeta; Ganjir, Manju

    2015-12-01

    Sr2MgSi2O7:Eu(2+) and Sr2MgSi2O7:Eu(2+),Dy(3+) long afterglow phosphors were synthesized under a weak reducing atmosphere by the traditional high temperature solid state reaction method. The synthesized phosphors were characterized by powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and photo-, thermo- and mechanoluminescence spectroscopic techniques. The phase structure of the sintered phosphor was an akermanite type structure, which belongs to tetragonal crystallography. The thermoluminescence properties of these phosphors were investigated and compared. Under ultraviolet light excitation, the emission spectra of both prepared phosphors were composed of a broad emission band peaking at 470 nm. When the Sr2MgSi2O7:Eu(2+) phosphor was co-doped with Dy(3+), the photoluminescence (PL), afterglow and mechanoluminescence (ML) intensity were strongly enhanced. The decay graph indicated that both the sintered phosphors contained fast decay and slow decay processes. The ML intensities of Sr2MgSi2O7:Eu(2+) and Sr2MgSi2O7:Eu(2+),Dy(3+) phosphors were increased proportionally with increasing impact velocity, a finding that suggests that these phosphors could be used as sensors to detect the stress of an object. PMID:25847277

  5. High color rendering index of remote-type white LEDs with multi-layered quantum dot-phosphor films and short-wavelength pass dichroic filters

    NASA Astrophysics Data System (ADS)

    Yoon, Hee Chang; Oh, Ji Hye; Do, Young Rag

    2014-09-01

    This paper introduces high color rendering index (CRI) white light-emitting diodes (W-LEDs) coated with red emitting (Sr,Ca)AlSiN3:Eu phosphors and yellowish-green emitting AgIn5S8/ZnS (AIS/ZS) quantum dots (QDs) on glass or a short-wavelength pass dichroic filter (SPDF), which transmit blue wavelength regions and reflect yellow wavelength regions. The red emitting (Sr,Ca)AlSiN3:Eu phosphor film is coated on glass and a SPDF using a screen printing method, and then the yellowish-green emitting AIS/ZS QDs are coated on the red phosphor (Sr,Ca)AlSiN3:Eu film-coated glass and SPDF using the electrospray (e-spray) method.To fabricate the red phosphor film, the optimum amount of phosphor is dispersed in a silicon binder to form a red phosphor paste. The AIS/ZS QDs are mixed with dimethylformamide (DMF), toluene, and poly(methyl methacrylate) (PMMA) for the e-spray coating. The substrates are spin-coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to fabricate a conductive surface. The CRI of the white LEDs is improved through inserting the red phosphor film between the QD layer and the glass substrate. Furthermore, the light intensities of the multi-layered phosphor films are enhanced through changing the glass substrate to the SPDF. The correlated color temperatures (CCTs) vary as a function of the phosphor concentration in the phosphor paste. The optical properties of the yellowish-green AIS/ZS QDs and red (Sr,Ca)AlSiN3:Eu phosphors are characterized using photoluminescence (PL), and the multi-layered QD-phosphor films are measured using electroluminescence (EL) with an InGaN blue LED (λmax = 450 nm) at 60 mA.

  6. Fluorescent lighting with aluminum nitride phosphors

    DOEpatents

    Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Srivastava, Alok M.

    2016-05-10

    A fluorescent lamp includes a glass envelope; at least two electrodes connected to the glass envelope; mercury vapor and an inert gas within the glass envelope; and a phosphor within the glass envelope, wherein the phosphor blend includes aluminum nitride. The phosphor may be a wurtzite (hexagonal) crystalline structure Al.sub.(1-x)M.sub.xN phosphor, where M may be drawn from beryllium, magnesium, calcium, strontium, barium, zinc, scandium, yttrium, lanthanum, cerium, praseodymium, europium, gadolinium, terbium, ytterbium, bismuth, manganese, silicon, germanium, tin, boron, or gallium is synthesized to include dopants to control its luminescence under ultraviolet excitation. The disclosed Al.sub.(1-x)M.sub.xN:Mn phosphor provides bright orange-red emission, comparable in efficiency and spectrum to that of the standard orange-red phosphor used in fluorescent lighting, Y.sub.2O.sub.3:Eu. Furthermore, it offers excellent lumen maintenance in a fluorescent lamp, and does not utilize "critical rare earths," minimizing sensitivity to fluctuating market prices for the rare earth elements.

  7. Global Threat Reduction Initiative Fuel-Thermo-Physical Characterization Project Quality Assurance Plan

    SciTech Connect

    Pereira, Mario M.; Slonecker, Bruce D.

    2012-06-01

    The charter of the Fuel Thermo-Physical Characterization Project is to ready Pacific Northwest National Laboratory (PNNL) facilities and processes for the receipt of unirradiated and irradiated low enriched uranium (LEU) molybdenum (U-Mo) fuel element samples, and to perform analysis to support the Global Threat Reduction Initiative conversion program. PNNL’s support for the program will include the establishment of post-irradiation examination processes, including thermo-physical properties, unique to the U.S. Department of Energy laboratories. These processes will ultimately support the submission of the base fuel qualification (BFQ) to the U.S. Nuclear Regulatory Commission (NRC) and revisions to High Performance Research Reactor Safety Analysis Reports to enable conversion from highly enriched uranium to LEU fuel. This quality assurance plan (QAP) provides the quality assurance requirements and processes that support the NRC BFQ. This QAP is designed to be used by project staff, and prescribes the required management control elements that are to be met and how they are implemented. Additional controls are captured in Fuel Thermo-Physical Characterization Project plans, existing procedures, and procedures to be developed that provide supplemental information on how work is conducted on the project.

  8. Characterizing the Physical and Thermal Properties of Planetary Regolith at Low Temperatures

    NASA Technical Reports Server (NTRS)

    Mantovani, James G.; Swanger, Adam; Townsend, Ivan I., III; Sibille, Laurent; Galloway, Gregory

    2014-01-01

    The success or failure of in-situ resource utilization for planetary surface exploration-whether for science, colonization, or commercialization-relies heavily on the design and implementation of systems that can effectively process planetary regolith and exploit its potential benefits. In most cases, this challenge necessarily includes the characterization of regolith properties at low temperatures (cryogenic). None of the nearby solar system destinations of interest, such as the moon, Mars and asteroids, possess a sufficient atmosphere to sustain the consistently "high" surface temperatures found on Earth. Therefore, they can experience permanent cryogenic temperatures or dramatic cyclical changes in surface temperature. Characterization of physical properties (e.g., specific heat, thermal and electrical conductivity) over the entire temperature profile is important when planning a mission to a planetary surface; however, the impact on mechanical properties due to the introduction of icy deposits must also be explored in order to devise effective and robust excavation technologies. The Granular Mechanics and Regolith Operations Laboratory and the Cryogenics Test Laboratory at NASA Kennedy Space Center are developing technologies and experimental methods to address these challenges and to aid in the characterization of the physical and mechanical properties of regolith at cryogenic temperatures. This paper will review the current state of knowledge concerning planetary regolith at low temperature, including that of icy regolith, and describe efforts to manipulate icy regolith through novel penetration and excavation techniques.

  9. Morphology control and luminescence properties of BaMgAl 10O 17:Eu 2+ phosphors prepared by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Zhou, Yonghui; Lin, Jun

    2005-02-01

    Starting from the aqueous solutions of metal nitrates with citric acid and polyethylene glycol (PEG) as additives, BaMgAl 10O 17:Eu 2+ (BAM:Eu 2+) phosphors were prepared by a two-step spray pyrolysis (SP) method. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectra were used to characterize the resulted BAM:Eu 2+ phosphors. The obtained BAM:Eu 2+ phosphor particles have spherical shape, submicron size (0.5-3 μm). The effects of process conditions of the spray pyrolysis, such as molecular weight and concentration of PEG, on the morphology and luminescence properties of phosphor particles were investigated. Adequate amount of PEG was necessary for obtaining spherical particles, and the optimum emission intensity could be obtained when the concentration of PEG was 0.03 g/ml in the precursor solution. Moreover, the emission intensity of the phosphors increased with increasing of metal ion concentration in the solution. Compared with the BAM:Eu 2+ phosphor prepared by citrate-gel method, spherical BAM:Eu 2+ phosphor particles showed a higher emission intensity.

  10. A Structured and Flexible Language for Physical Activity Assessment and Characterization

    PubMed Central

    Silva, Pedro; Andrade, Maria Teresa; Carvalho, Pedro; Mota, Jorge

    2013-01-01

    Developing more accurate assessments of physical activity (PA) and sedentary behavior (SB) is an important public health research priority. Assessing PA and SB is challenging in all segments of the population, but it is especially difficult in children due to cognitive limitations and more sporadic and intermittent activity patterns. Moreover, they are influenced by several factors including temporal-spatial constraints and social conditions. To accurately assess PA and SB, it is essential to clearly define methods for describing all these factors. The goal of this paper is to potentiate advances in the field by proposing a base ontology for characterizing physical activity, sedentary behavior, and the context in which it occurs. The ontology would establish a flexible base language to facilitate standardized descriptions of these behaviors for researchers and public health professionals. PMID:26464878

  11. Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

    PubMed Central

    Hardman, Kyle S.; Bennetts, Shayne; Debs, John E.; Kuhn, Carlos C. N.; McDonald, Gordon D.; Robins, Nick

    2014-01-01

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs1,2. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling1,2 makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman3, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included. PMID:24796259

  12. Construction and characterization of external cavity diode lasers for atomic physics.

    PubMed

    Hardman, Kyle S; Bennetts, Shayne; Debs, John E; Kuhn, Carlos C N; McDonald, Gordon D; Robins, Nick

    2014-01-01

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included. PMID:24796259

  13. MULTI-PHOTON PHOSPHOR FEASIBILITY RESEARCH

    SciTech Connect

    R. Graham; W. Chow

    2003-05-01

    Development of multi-photon phosphor materials for discharge lamps represents a goal that would achieve up to a doubling of discharge (fluorescent) lamp efficacy. This report reviews the existing literature on multi-photon phosphors, identifies obstacles in developing such phosphors, and recommends directions for future research to address these obstacles. To critically examine issues involved in developing a multi-photon phosphor, the project brought together a team of experts from universities, national laboratories, and an industrial lamp manufacturer. Results and findings are organized into three categories: (1) Multi-Photon Systems and Processes, (2) Chemistry and Materials Issues, and (3) Concepts and Models. Multi-Photon Systems and Processes: This category focuses on how to use our current understanding of multi-photon phosphor systems to design new phosphor systems for application in fluorescent lamps. The quickest way to develop multi-photon lamp phosphors lies in finding sensitizer ions for Gd{sup 3+} and identifying activator ions to red shift the blue emission from Pr{sup 3+} due to the {sup 1}S{sub 0} {yields} {sup 1}I{sub 6} transition associated with the first cascading step. Success in either of these developments would lead to more efficient fluorescent lamps. Chemistry and Materials Issues: The most promising multi-photon phosphors are found in fluoride hosts. However, stability of fluorides in environments typically found in fluorescent lamps needs to be greatly improved. Experimental investigation of fluorides in actual lamp environments needs to be undertaken while working on oxide and oxyfluoride alternative systems for backup. Concepts and Models: Successful design of a multi-photon phosphor system based on cascading transitions of Gd{sup 3+} and Pr{sup 3+} depends critically on how the former can be sensitized and the latter can sensitize an activator ion. Methods to predict energy level diagrams and Judd-Ofelt parameters of multi

  14. Materials Characterization Challenges for the Semiconductor Industry: Physical and Chemical Techniques

    NASA Astrophysics Data System (ADS)

    Shaffner, Thomas J.

    2002-03-01

    Materials and device characterization serve the essential role of defining how an integrated circuit differs from its intended design and function. Over the years, a variety of physical and chemical techniques based on probes of electrons, ions and photons have evolved to fill this need. Each has a specialized application for resolving specific problems related to smaller geometry, thin film composition, and shallow junction profiling. As we enter the internet era, demands for higher speed, reliability and performance from both silicon and compound semiconductor materials and circuits is prematurely pushing sophisticated and costly R&D characterization tools closer to the manufacturing environment. This review illustrates how this is happening with emphasis on new developments in electron microscopy, ion backscattering, scanning probe methodologies, and even futuristic methods, such as the position-sensitive atom probe.

  15. Characterization of Semi-Insulating CdTe Crystals Grown by Horizontal Seeded Physical Vapor Transport

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, K.; Feth, S.; Chen, H.; Burger, A.; Su, Ching-Hua

    1998-01-01

    CdTe crystals were grown by horizontal seeded physical vapor transport technique in uncoated and boron nitride coated fused silica ampoules with the source materials near the congruent sublimation condition. The grown crystals were characterized by current-voltage measurements, low temperature photoluminescence spectroscopy, near IR transmission optical microscopy, spark source mass spectroscopy and chemical etching. The measured resistivities of the crystals were in the high-10(exp 8) ohm-cm range. Although the crystal grown in the boron nitride coating was contaminated with boron from the photoluminescence measurements, the coating yielded a single crystal with no inclusions or precipitates.

  16. Seeded Physical Vapor Transport of Cadmium-Zinc Telluride Crystals: Growth and Characterization

    NASA Technical Reports Server (NTRS)

    Palosz, W.; George, M. A.; Collins, E. E.; Chen, K.-T.; Zhang, Y.; Burger, A.

    1997-01-01

    Crystals of Cd(1-x)Zn(x)Te with x = 0.2 and 40 g in weight were grown on monocrystalline cadmium-zinc telluride seeds by closed-ampoule physical vapor transport with or without excess (Cd + Zn) in the vapor phase. Two post-growth cool-down rates were used. The crystals were characterized using low temperature photoluminescence, atomic force microscopy, chemical etching, X-ray diffraction and electrical measurements. No formation of a second, ZnTe-rich phase was observed.

  17. Identification and characterization of the critical physically demanding tasks encountered by correctional officers.

    PubMed

    Jamnik, Veronica K; Thomas, Scott G; Shaw, Jim A; Gledhill, Norman

    2010-02-01

    The purpose of this investigation was to identify the critical tasks encountered by correctional officers (COs) on the job and to conduct a comprehensive assessment and characterization of the physical demands of these tasks. These are the first steps in developing a fitness screening test for COs in compliance with recent legislation. The most important, physically demanding, and frequently occurring tasks were identified using Delphi methodology, focus groups, and questionnaire responses from 190 experienced front-line COs. These tasks were structured into emergency response scenarios for which a physical and physiological characterization was conducted to verify their relative physical demands analysis. Oxygen consumption and the forces exerted by COs were quantified while they were responding and then controlling and restraining inmates. The female COs used less force than the male COs did to control and restrain the same inmates (body control = 46 vs. 60 kg, wrist hold = 32 vs. 49 kg, and arm retraction = 37 vs. 47 kg) and did not exert their maximal strength during their control and restraint activities. The mean oxygen consumption of the female and male COs while performing the on-the-job tasks was similar (39.5 vs. 38.5 mL.kg-1.min-1). We concluded that the essential components of a fitness screening protocol for CO applicants are cell search, expeditious response, body control, arm restraint, inmate relocation, and an assessment of aerobic fitness. The criterion performance standards for completing these tasks in a circuit were set at the job performance level of safe and efficient female COs. PMID:20130666

  18. MULTI-ATTRIBUTE SEISMIC/ROCK PHYSICS APPROACH TO CHARACTERIZING FRACTURED RESERVOIRS

    SciTech Connect

    Gary Mavko

    2000-10-01

    This project consists of three key interrelated Phases, each focusing on the central issue of imaging and quantifying fractured reservoirs, through improved integration of the principles of rock physics, geology, and seismic wave propagation. This report summarizes the results of Phase I of the project. The key to successful development of low permeability reservoirs lies in reliably characterizing fractures. Fractures play a crucial role in controlling almost all of the fluid transport in tight reservoirs. Current seismic methods to characterize fractures depend on various anisotropic wave propagation signatures that can arise from aligned fractures. We are pursuing an integrated study that relates to high-resolution seismic images of natural fractures to the rock parameters that control the storage and mobility of fluids. Our goal is to go beyond the current state-of-the art to develop and demonstrate next generation methodologies for detecting and quantitatively characterizing fracture zones using seismic measurements. Our study incorporates 3 key elements: (1) Theoretical rock physics studies of the anisotropic viscoelastic signatures of fractured rocks, including up scaling analysis and rock-fluid interactions to define the factors relating fractures in the lab and in the field. (2) Modeling of optimal seismic attributes, including offset and azimuth dependence of travel time, amplitude, impedance and spectral signatures of anisotropic fractured rocks. We will quantify the information content of combinations of seismic attributes, and the impact of multi-attribute analyses in reducing uncertainty in fracture interpretations. (3) Integration and interpretation of seismic, well log, and laboratory data, incorporating field geologic fracture characterization and the theoretical results of items 1 and 2 above. The focal point for this project is the demonstration of these methodologies in the Marathon Oil Company Yates Field in West Texas.

  19. Synthesis, structure and photoluminescence properties of Sm3+-doped BiOBr phosphor

    NASA Astrophysics Data System (ADS)

    Halappa, Pramod; Shivakumara, C.; Saraf, Rohit; Nagabhushana, H.

    2016-05-01

    Well-crystallized tetragonal layered BiOBr and Bi0.95Sm0.05OBr phosphors were prepared by the solid state method. These compounds were characterized using powder X-Ray diffraction and photoluminescence technique. In PL spectra, the electric dipole transitions dominate than other transitions which indicate that the Sm3+ ions occupy a site with an inversion center of BiOBr. CIE chromaticity diagram confirmed that these phosphors can be useful in the fabrication of red component in white light emitting diodes (WLEDs) for display device applications.

  20. Optical and thermal performance of a remote phosphor plate

    NASA Astrophysics Data System (ADS)

    Mou, Xi; Narendran, Nadarajah; Zhu, Yiting; Perera, Indika U.

    2014-09-01

    The objective of this study was to understand how optical and thermal performances are impacted in a remote phosphor LED (light-emitting diode) system when the phosphor plate thickness and phosphor concentration change with a fixed amount of a commonly used YAG:Ce phosphor. In the first part of this two-part study, an optical raytracing analysis was carried out to quantify the optical power and the color properties as a function of remote phosphor plate thickness, and a laboratory experiment was conducted to verify the results obtained from the raytracing analysis and also to examine the phosphor temperature variation due to thickness change.

  1. Phosphor blends for high-CRI fluorescent lamps

    DOEpatents

    Setlur, Anant Achyut; Srivastava, Alok Mani; Comanzo, Holly Ann; Manivannan, Venkatesan; Beers, William Winder; Toth, Katalin; Balazs, Laszlo D.

    2008-06-24

    A phosphor blend comprises at least two phosphors each selected from one of the groups of phosphors that absorb UV electromagnetic radiation and emit in a region of visible light. The phosphor blend can be applied to a discharge gas radiation source to produce light sources having high color rendering index. A phosphor blend is advantageously includes the phosphor (Tb,Y,LuLa,Gd).sub.x(Al,Ga).sub.yO.sub.12:Ce.sup.3+, wherein x is in the range from about 2.8 to and including 3 and y is in the range from about 4 to and including 5.

  2. Blue-green phosphor for fluorescent lighting applications

    DOEpatents

    Srivastava, Alok; Comanzo, Holly; Manivannan, Venkatesan; Setlur, Anant Achyut

    2005-03-15

    A fluorescent lamp including a phosphor layer including Sr.sub.4 Al.sub.14 O.sub.25 :Eu.sup.2+ (SAE) and at least one of each of a red, green and blue emitting phosphor. The phosphor layer can optionally include an additional, deep red phosphor and a yellow emitting phosphor. The resulting lamp will exhibit a white light having a color rendering index of 90 or higher with a correlated color temperature of from 2500 to 10000 Kelvin. The use of SAE in phosphor blends of lamps results in high CRI light sources with increased stability and acceptable lumen maintenance over, the course of the lamp life.

  3. Phosphorous-diffusion gettering in the presence of a nonequilibrium concentration of silicon interstitials: A quantitative model

    SciTech Connect

    Spiecker, E.; Seibt, M.; Schroeter, W.

    1997-04-01

    A quantitative model of phosphorous-diffusion gettering in silicon is presented, which combines the effects of segregation and self-interstitial injection on the distribution of dissolved metallic impurities. The model describes metal diffusion both in the bulk and in the highly phosphorous-doped layer and makes it possible to include phosphorous-diffusion models. By analyzing an approximate solution for the quasi-steady-state metal distribution, we show that for impurities like gold and platinum self-interstitial injection enhances the gettering efficiency compared to pure segregation. We apply the results to phosphorous-diffusion gettering of gold and demonstrate that all relevant features of recently measured gold distributions can be interpreted consistently. For 3d metals, which are predominantly dissolved on interstitial sites in intrinsic silicon, the model allows us to include the formation of precipitates resulting from self-interstitial injection as proposed earlier. {copyright} {ital 1997} {ital The American Physical Society}

  4. Hydrothermal synthesis and luminescence properties of KLa):Eu3+ phosphor

    NASA Astrophysics Data System (ADS)

    Yang, Zaifa; Sun, Yumei; Han, Liu; Xu, Denghui; Sun, Jiayue

    2016-04-01

    KLa):Eu3+ phosphors were prepared by the hydrothermal method. The after tuning of synthesis time and the ratio of the ethylene glycol to water ratio made the phosphor present different morphologies, including peanut-like shape and spheres. The samples were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), diffuse reflectance spectrum, and fluorescence spectrum. Under the excitation of 397 nm near-ultraviolet, the typical red emission produced by Eu3+ ions can be observed. And the phosphors show strong red light around 612 nm, attributed to D→F transition of Eu ion. The luminescence properties of the as-prepared phosphors were studied based on changing the synthesis condition. It is found that the synthesis time and the changing of the ratio of ethylene glycol to water play the crucial role in the formation of morphology. The optimum dopant concentration of Eu ions in KLa):Eu3+ is around 7 mol. %. Moreover, the fluorescence decay curve and thermal stability of luminescence were also investigated in detail. The Commission International de I'Eclairage coordinates of KLa):0.07Eu3+ located in the red reddish region. All the results suggest that KLa):0.07Eu3+ might be a promising reddish-orange emitting phosphor used in white light-emitting diodes (w-LED).

  5. Near-Infrared Quantum Cutting in Yb3+ Doped SrMoO4 Phosphors.

    PubMed

    Luo, Xiaobing; Shen, Jun; Huang, He; Xu, Lu; Wang, Zhixiang; Chen, Yang; Li, Li

    2016-04-01

    Efficient near-infrared (NIR) quantum cutting (QC) has been demonstrated in Yb3+ doped SrMoO4 phosphors synthesized by the high-temperature solid-state reaction method. The obtained SrMoO4:Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra and decay lifetime to understand the observed near-infrared quantum cutting phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of SrMoO4 and exhibit good crystallinity. The experimental results showed that the strong visible molybdate (MoO2-(4)) emission around 493 nm and near-infrared (NIR) emission around 1000 nm from Yb3+(2F(5/2)-->2F(7/2)) of SrMoO4:Yb3+ phosphors were observed under ultraviolet (290 nm) excitation. The Yb + concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches as high as 10 mol%. The cooperative energy transfer (CET) mechanism was also discussed in detail. The broadband NIR QC phosphors may possibly have potential application in enhancing the conversion efficiency of solar cells. PMID:27451655

  6. Sm(3+)-doped Ba3Bi(PO4)3 orange reddish emitting phosphor.

    PubMed

    Yang, Fu; Yang, Zhiping; Yu, Quanmao; Liu, Yufeng; Li, Xu; Lu, Fachun

    2013-03-15

    Ba(3)Bi(PO(4))(3):Sm(3+) phosphors were prepared via solid state reaction process. The crystal structure of the phosphor was characterized by XRD. The PL properties of Ba(3)Bi(PO(4))(3):Sm(3+) were investigated. The optimized phosphor with the composition of Ba(3)Bi(PO(4))(3):0.06Sm(3+) presents the several excitation bands from 300 to 500 nm, and exhibits very good luminescence properties. Under the excitation of ultraviolet 373, 401 and blue 467 nm, the phosphor presented red luminescence with dominating emissions at 563, 599, 646 and 709 nm, corresponding to (4)G(5/2)→(6)H(J) (J=5/2, 7/2, 9/2 and 11/9) transitions, respectively. The critical distance was calculated to be 21.0 Å. The energy transfer type between Sm(3+) ions was confirmed as the d-d interaction by using the Van Uitert model. The chromatic properties of the typical sample Ba(3)Bi(PO(4))(3):0.06Sm(3+) phosphor have been found to have chromaticity coordinates of (0.59, 0.38), under the excitation of 401 nm. PMID:23391850

  7. Luminescence properties of phosphate phosphor Ba3Y(PO4)3:Sm3+

    NASA Astrophysics Data System (ADS)

    Yang, Fu; Liu, Yufeng; Tian, Xiaodong; Dong, Guoyi; Yu, Quanmao

    2015-05-01

    A series of reddish orange-emitting phosphate phosphors Ba3Y1-x(PO4)3:xSm3+(0.01≤x≤0.20) were synthesized by solid-state reaction. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of as-synthesized phosphors. The optimized phosphors Ba3Y0.95(PO4)3:0.05Sm3+ present several excitation bands from 300 to 500 nm, and exhibit intense reddish orange-emitting properties. The energy transfer type between Sm3+ ions was confirmed as d-d interaction by using Van Uitert model. The chromatic properties of the typical sample Ba3Y(PO4)3:0.05Sm3+ phosphor have been found to have chromaticity coordinates of (0.583, 0.405), which are located in reddish orange region under the excitation of 401 nm. These results indicated that Ba3Y(PO4)3:Sm3+ phosphors have potential applications in the field of lighting and display due to their effective excitation in the near-ultraviolet range.

  8. Luminescent properties of orange emissive Sm3+-activated thermally stable phosphate phosphor for optical devices.

    PubMed

    Ratnam, B V; Jayasimhadri, M; Jang, Kiwan

    2014-11-11

    Rare earth ion activated orthophosphates have a great deal of interest due to their thermal stability for white light emitting diodes. In this regard, thermally stable Sm3+ doped NaCaPO4 (NCP) phosphor was synthesized by conventional solid state reaction technique. The phase and the structure of the as prepared powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), FT-IR, emission and excitation properties were extensively investigated for NCP phosphors. X-ray diffraction analysis confirmed the formation of NaCaPO4 with orthorhombic structure. The excitation spectra indicate that this phosphor can be effectively excited by UV light from 350 to 500 nm. All the transitions in the excitation spectrum of Sm3+ start from the ground state 6H5/2 to various excited states. The emission spectra indicated that the emitted radiation was dominated by the emission peak wavelength at 599 nm originated from the transition of 4G5/2→6H7/2. The optimum concentration of Sm3+ is determined as 1.0 mol% based on the concentration dependent emission spectra. These results suggest that the NaCaPO4:Sm3+ phosphor is a promising orange emitting phosphor under 404 nm excitation with CIE coordinates of x=0.545, y=0.41, which might be used in the development of materials for LED's and other optical devices in the visible region. PMID:24892535

  9. Material properties and structural characterization of M3Si6O12N2:Eu2+ (M = Ba, Sr)--a comprehensive study on a promising green phosphor for pc-LEDs.

    PubMed

    Braun, Cordula; Seibald, Markus; Börger, Saskia L; Oeckler, Oliver; Boyko, Teak D; Moewes, Alexander; Miehe, Gerhard; Tücks, Andreas; Schnick, Wolfgang

    2010-08-16

    The efficient green phosphor Ba(3)Si(6)O(12)N(2):Eu(2+) and its solid-solution series Ba(3-x)Sr(x)Si(6)O(12)N(2) (with x approximately = 0.4 and 1) were synthesized in a radio-frequency furnace under nitrogen atmosphere at temperatures up to 1425 degrees C. The crystal structure (Ba(3)Si(6)O(12)N(2), space group P3 (no. 147), a = 7.5218(1), c = 6.4684(1) A, wR2 = 0.048, Z = 1) has been solved and refined on the basis of both single-crystal and powder X-ray diffraction data. Ba(3)Si(6)O(12)N(2):Eu(2+) is a layer-like oxonitridosilicate and consists of vertex-sharing SiO(3)N-tetrahedra forming 6er- and 4er-rings as fundamental building units (FBU). The nitrogen atoms are connected to three silicon atoms (N3), while the oxygen atoms are either terminally bound (O1) or bridge two silicon atoms (O2) (numbers in superscripted square brackets after atoms indicate the coordination number of the atom in question). Two crystallographically independent Ba(2+) sites are situated between the silicate layers. Luminescence investigations have shown that Ba(3)Si(6)O(12)N(2):Eu(2+) exhibits excellent luminescence properties (emission maximum at approximately 527 nm, full width at half maximum (FWHM) of approximately 65 nm, low thermal quenching), which provides potential for industrial application in phosphor-converted light-emitting diodes (pc-LEDs). In-situ high-pressure and high-temperature investigations with synchrotron X-ray diffraction indicate decomposition of Ba(3)Si(6)O(12)N(2) under these conditions. The band gap of Ba(3)Si(6)O(12)N(2):Eu(2+) was measured to be 7.05+/-0.25 eV by means of X-ray emission spectroscopy (XES) and X-ray absorption near edge spectroscopy (XANES). This agrees well with calculated band gap of 6.93 eV using the mBJ-GGA potential. Bonding to the Ba atoms is highly ionic with only the 4p(3/2) orbitals participating in covalent bonds. The valence band consists primarily of N and O p states and the conduction band contains primarily Ba d and f states

  10. Physical and optical dot gain: characterization and relation to dot shape and paper properties

    NASA Astrophysics Data System (ADS)

    Namedanian, Mahziar; Nyström, Daniel; Zitinski Elias, Paula; Gooran, Sasan

    2014-01-01

    The tone value increase in halftone printing commonly referred to as dot gain actually encompasses two fundamentally different phenomena. Physical dot gain refers to the fact that the size of the printed halftone dots differs from their nominal size, and is related to the printing process. Optical dot gain originates from light scattering inside the substrate, causing light exchanges between different chromatic areas. Due to their different intrinsic nature, physical and optical dot gains need to be treated separately. In this study, we characterize and compare the dot gain properties for offset prints on coated and uncoated paper, using AM and first and second generation FM halftoning. Spectral measurements are used to compute the total dot gain. Microscopic images are used to separate the physical and optical dot gain, to study ink spreading and ink penetration, and to compute the Modulation Transfer Function (MTF) for the different substrates. The experimental results show that the physical dot gain depends on ink penetration and ink spreading properties. Microscopic images of the prints reveal that the ink penetrates into the pores and cavities of the uncoated paper, resulting in inhomogeneous dot shapes. For the coated paper, the ink spread on top of the surface, giving a more homogenous dot shape, but also covering a larger area, and hence larger physical dot gain. The experimental results further show that the total dot gain is larger for the uncoated paper, because of larger optical dot gain. The effect of optical dot gain depends on the lateral light scattering within the substrate, the size of the halftone dots, and on the halftone dot shape, especially the dot perimeter.

  11. Synthesis, vibrational and luminescence studies on Eu3+:KY(WO4)2 red phosphors

    NASA Astrophysics Data System (ADS)

    Rasu, K. Kavi; Durairajan, A.; Balaji, D.; Babu, S. Moorthy

    2015-06-01

    Eu3+:KY(WO4)2 (Eu3+:KYW) phosphors were synthesized by sol-gel method using citric acid as a chelator and ethylene glycol as a binder. The crystallinity, organic liberation and tungstate bridge formation and excitation and emission properties of the synthesized phosphors were characterized by powder XRD, FT-IR, Raman and fluorescence analysis respectively. Powder XRD confirms the formation of monoclinic crystalline structure with space group C2/c. Organic liberation with respect to thermal treatments was analyzed in FT-IR. Raman results indicate different vibration mode related to monoclinic structure. The strong red emission at 615 nm (5D0→ 7F2) of the phosphors under the near UV excitation was examined by the fluorescence studies.

  12. Photoluminescence study of nanocrystalline Y2O3:Ho3+ phosphor.

    PubMed

    Singh, Vijay; Rai, Vineet Kumar; Voss, Benjamin; Haase, Markus; Chakradhar, R P S; Thirupathi Naidu, D; Kim, Sang Hwan

    2013-05-15

    The Y2O3:Ho(3+) powder phosphors have been prepared by using low temperature combustion method. Powder X-ray diffraction, scanning electron microscope and transmission electron microscopy techniques were used to characterize the as-prepared phosphor. The UV-Vis-NIR absorption, excitation and emission studies have been performed and the phenomenological Judd-Ofelt intensity parameters which are critically important in calculating the radiative properties and stimulated emission crosssection have been calculated by using Judd-Ofelt theory. Based on the calculated values of the inter electronic parameter, covalency and bonding parameter the bonding between the Ho(3+) ions and surrounding oxygen atoms have been found to be covalent in nature. The color purity has also been verified by using the chromaticity diagram. The analysis shows that the Y2O3:Ho(3+) phosphor may be used for producing the green light emitting diodes and display applications. PMID:23524388

  13. Photoluminescence study of nanocrystalline Y2O3:Ho3+ phosphor

    NASA Astrophysics Data System (ADS)

    Singh, Vijay; Rai, Vineet Kumar; Voss, Benjamin; Haase, Markus; Chakradhar, R. P. S.; Thirupathi Naidu, D.; Kim, Sang Hwan

    2013-05-01

    The Y2O3:Ho3+ powder phosphors have been prepared by using low temperature combustion method. Powder X-ray diffraction, scanning electron microscope and transmission electron microscopy techniques were used to characterize the as-prepared phosphor. The UV-Vis-NIR absorption, excitation and emission studies have been performed and the phenomenological Judd-Ofelt intensity parameters which are critically important in calculating the radiative properties and stimulated emission crosssection have been calculated by using Judd-Ofelt theory. Based on the calculated values of the inter electronic parameter, covalency and bonding parameter the bonding between the Ho3+ ions and surrounding oxygen atoms have been found to be covalent in nature. The color purity has also been verified by using the chromaticity diagram. The analysis shows that the Y2O3:Ho3+ phosphor may be used for producing the green light emitting diodes and display applications.

  14. Luminescence properties of Tb3+ doped Sr2SnO4 green phosphor in UV/VUV regions.

    PubMed

    Srinivas, M; Rao, B Appa; Vithal, M; Rao, P Raghava

    2013-01-01

    Polycrystalline Sr2SnO4 phosphors doped with Tb(3+) were prepared by conventional solid-state reaction method. Materials were characterized by powder XRD and EDS techniques. The luminescence properties of these materials were investigated under UV and VUV excitation. Upon excitation at 272 nm, phosphors exhibited intense emissions at 492 and 543 nm due to (5)D4 → (7)F6 and (5)D4 → (7)F5 transitions of Tb(3+) ions, respectively. Materials also exhibited strong emissions from these transitions under VUV excitation at 147, 173 and 230 nm. Quantitative analysis of the spectra indicated probable applications of these phosphors for PDP and other display devices as green emitting phosphors. PMID:22733625

  15. Global Threat Reduction Initiative Fuel Thermo-Physical Characterization Project: Sample Management Plan

    SciTech Connect

    Casella, Amanda J.; Pereira, Mario M.; Steen, Franciska H.

    2013-01-01

    This sample management plan provides guidelines for sectioning, preparation, acceptance criteria, analytical path, and end-of-life disposal for the fuel element segments utilized in the Global Threat Reduction Initiative (GTRI), Fuel Thermo-Physical Characterization Project. The Fuel Thermo-Physical Characterization Project is tasked with analysis of irradiated Low Enriched Uranium (LEU) Molybdenum (U-Mo) fuel element samples to support the GTRI conversion program. Sample analysis may include optical microscopy (OM), scanning electron microscopy (SEM) fuel-surface interface analysis, gas pycnometry (density) measurements, laser flash analysis (LFA), differential scanning calorimetry (DSC), thermogravimetry and differential thermal analysis with mass spectroscopy (TG /DTA-MS), Inductively Coupled Plasma Spectrophotometry (ICP), alpha spectroscopy, and Thermal Ionization Mass Spectroscopy (TIMS). The project will utilize existing Radiochemical Processing Laboratory (RPL) operating, technical, and administrative procedures for sample receipt, processing, and analyses. Test instructions (TIs), which are documents used to provide specific details regarding the implementation of an existing RPL approved technical or operational procedure, will also be used to communicate to staff project specific parameters requested by the Principal Investigator (PI). TIs will be developed, reviewed, and issued in accordance with the latest revision of the RPL-PLN-700, RPL Operations Plan. Additionally, the PI must approve all project test instructions and red-line changes to test instructions.

  16. Electrochemically produced films and polycrystalline salts of C60n-: Their physical characterization

    SciTech Connect

    Jones, M.T.; Subramanian, R.; Boulas, P.

    1994-12-31

    The discovery of C60 and its anionic salts C60{sup n-} (n = 1, 2, or 3) has provided a series of new materials with a wide range of very interesting chemical and physical properties such as ferromagnetism, nonlinear optical activity, semiconductivity and superconductivity. To date, relatively few salts of the anions of C60 have been studied because until recently a simple synthesis procedure did not exist. The authors recently developed simple and efficient methods for preparing thin films (prepared electrochemically) of both C60 and C60n- (n = 1, 2, or 3) and for preparing anion salts of C60 (prepared electrochemically and chemically). The authors now report the spectroscopic characterization of some of these materials. For example, studies of the temperature dependence of the Raman spectra of selected films (such as C60 and Cs3C60) are discussed. Also discussed are the ESR studies of a series of polycrystalline C60 anion salts derived from films as well as from the facile chemical preparation methods which are presented. The results of these spectroscopic studies are discussed as are results from other physical methods of characterization.

  17. Near-infrared dyes and upconverting phosphors as biomolecule labels and probes

    NASA Astrophysics Data System (ADS)

    Patonay, Gabor; Strekowski, Lucjan; Nguyen, Diem-Ngoc; Seok, Kim Jun

    2007-02-01

    Near-Infrared (NIR) absorbing chromophores have been used in analytical and bioanalytical chemistry extensively, including for determination of properties of biomolecules, DNA sequencing, immunoassays, capillary electrophoresis (CE) separations, etc. The major analytical advantages of these dyes are low background interference and high molar absorptivities. NIR dyes have additional advantages due to their sensitivity to microenvironmental changes. Spectral changes induced by the microenvironment are not desirable if the labels are used as a simple reporting group, e.g., during a biorecognition reaction. For these applications upconverting phosphors seem to be a better choice. There are several difficulties in utilizing upconverting phosphors as reporting labels. These are: large physical size, no reactive groups and insolubility in aqueous systems. This presentation will discuss how these difficulties can be overcome for bioanalytical and forensic applications. During these studies we also have investigated how to reduce physical size of the phosphor by simple grinding without losing activity and how to attach reactive moiety to the phosphor to covalently bind to the biomolecule of interest. It has to be emphasized that the described approach is not suitable for medical applications and the results of this research are not applicable in medical applications. For bioanalytical and forensic applications upconverting phosphors used as reporting labels have several advantages. They are excited with lasers that are red shifted respective to phosphorescence, resulting in no light scatter issues during detection. Also some phosphors are excited using eye safe lasers. In addition energy transfer to NIR dyes is possible, allowing detection schemes using donor-acceptor pairs. Data is presented to illustrate the feasibility of this phenomenon. If microenvironmental sensitivity is required, then specially designed NIR dyes can be used as acceptor labels. Several novel dyes

  18. Dy3+-activated NaM4(VO4)3 (M = Ca, Ba, Sr) phosphor for near-UV solid-state lighting.

    PubMed

    Singh, Roshani; Dhoble, S J

    2011-01-01

    We report the photoluminescence characterization of Dy(3+)-activated NaM(4)(VO(4))(3) (M = Ca, Ba, Sr) phosphors prepared by a solid-state method. The synthesis was confirmed by X-ray diffraction (XRD) characterization and photoluminescence (PL) emission results showed sharp blue and yellow bands for NaM(4)(VO(4))(3) (M = Ca, Ba, Sr):Dy(3+) phosphors at the excitation wavelength of 323 nm, which is near-UV excitation. Thus, these phosphors could be applicable for near-UV excited solid-state lighting devices. PMID:21618681

  19. Narrow line-width phosphors for phosphor-converted white light emitting diodes

    NASA Astrophysics Data System (ADS)

    Khanna, Aloka

    The luminous efficacy of present day phosphor-converted white LEDs is limited by phosphors with broad spectral emission in the long wavelength visible range (600-700 nm). The light output from the cool-white LEDs that do not use a red phosphor is 30-35% higher than the warm white LEDs fabricated with a red phosphor in addition to the yellow phosphor. However, the CRI of cool-white LEDs is significantly lower (~60-70) than the CRI of the warm white LEDs (~80-95) due to lack of the red photons in the emission spectrum. Therefore, a trade-off exists between luminous efficacy and color rendering capability of light generated by phosphor-converted white LEDs. In order to solve this problem, an efficient red phosphor with considerably narrow full width of half maxima (~5-10 nm) and emission in the 600-650 nm wavelength range is required. The narrow spectral line-width can be achieved by introducing trivalent lanthanide ions like Eu3+, Pr3+ and Sm3+ (λpeak- 615 nm, 650 nm, 655 nm) in oxide host lattices although the high energy gaps of these hosts makes these phosphors unsuitable for excitation with near-UV/Blue (380-470 nm) LED sources. Therefore, the goal of this project is two-fold- to develop new material systems which can serve as potential hosts for trivalent lanthanide ions like Eu3+, Pr3+ and Sm3+ (λpeak- 615 nm, 650 nm, 655 nm) with strong excitation bands in the near-UV/blue wavelength region (380-470 nm) and improve the efficiency of the known oxide phosphors doped with trivalent lanthanide ions and the novel phosphors via crystal growth processes. Moreover, phosphors in the green-yellow wavelength region with a narrow emission line-width have the potential of improving the luminous efficacy of the phosphor-converted LEDs as the human eye sensitivity curve peaks at 555 nm. Thus, in parallel with the narrow line-width red phosphor research, new compositions doped with Tb3+ (550 nm), Dy3+ (575 nm), etc. are being explored with strong excitation bands in near

  20. Crystalline rare-earth activated oxyorthosilicate phosphor

    DOEpatents

    McClellan, Kenneth J.; Cooke, D. Wayne

    2004-02-10

    Crystalline, transparent, rare-earth activated lutetium oxyorthosilicate phosphor. The phosphor consists essentially of lutetium yttrium oxyorthosilicate activated with a rare-earth metal dopant M and having the general formula Lu(.sub.2-x-z)Y.sub.x M.sub.z SiO.sub.5, wherein 0.00.ltoreq.x.ltoreq.1.95, wherein 0.001.ltoreq.z.ltoreq.0.02, and wherein M is selected from Sm, Tb, Tm, Eu, Yb, and Pr. The phosphor also consists essentially of lutetium gadolinium oxyorthosilicate activated with a rare-earth metal dopant M and having the general formula Lu(.sub.2-x-z)Gd.sub.x M.sub.z SiO.sub.5, wherein 0.00.ltoreq.x.ltoreq.1.95, wherein 0.001.ltoreq.z.ltoreq.0.02, and wherein M is selected from Sm, Tb, Tm, Eu, Yb, and Pr. The phosphor also consists essentially of gadolinium yttrium oxyorthosilicate activated with a rare-earth metal dopant M and having the general formula Gd(.sub.2-x-z)Y.sub.x M.sub.z SiO.sub.5, wherein 0.00.ltoreq.x.ltoreq.1.95, wherein 0.001.ltoreq.z.ltoreq.0.02, and wherein M is selected from Sm, Tb, Tm, Eu, Yb, and Pr. The phosphor may be optically coupled to a photodetector to provide a radiation detector.

  1. Color stable manganese-doped phosphors

    DOEpatents

    Lyons, Robert Joseph; Setlur, Anant Achyut; Deshpande, Anirundha Rajendra; Grigorov, Ljudmil Slavchev

    2014-04-29

    A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor material radiationally coupled to the light source. The phosphor material includes a color-stable Mn.sup.+4 doped phosphor prepared by a process including providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof.

  2. Color stable manganese-doped phosphors

    DOEpatents

    Lyons, Robert Joseph; Setlur, Anant Achyut; Deshpande, Anirudha Rajendra; Grigorov, Ljudmil Slavchev

    2012-08-28

    A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

  3. Infrared and visible emissions of rare-earth-doped CeO2 phosphor.

    PubMed

    Chandrakar, D; Kaur, J; Dubey, V; Suryanarayana, N S; Parganiha, Y

    2015-12-01

    This paper reports the synthesis and characterization of Er(3+)-doped CeO2 phosphor with variable concentrations of erbium. The sample was synthesized using a solid-state reaction method, which is useful for the large-scale production of phosphors and is also eco-friendly. The prepared sample was characterized using an X-ray diffraction (XRD) technique. The XRD pattern confirmed that sample has the pure cubic fluorite crystal structure of CeO2. The crystallite size of the prepared phosphor was determined by Scherer's formula and the crystallite size giving an intense XRD peak is 40.06 nm. The surface morphology of the phosphor was determined by field emission gun scanning electron microscopy (FEGSEM). From the FEGSEM image, good surface morphology with some agglomerates was found. The functional group in the prepared sample was analysed by Fourier transform infrared (FTIR) spectroscopy. All samples prepared with variable concentrations of Er(3+) (0.1-2 mol%) were studied by photoluminescence analysis and it was found that the excitation spectra of the prepared phosphor shows broad excitation centred at 251 nm. Emission spectra at different concentrations of Er(3+) show strong peaks at 413 and 470 nm and a weaker peak at 594 nm. The dominant peaks at 413 and 470 nm are caused by the allowed electronic transition (4)S3/2 → (4)I15/2 and the weaker transition at 594 nm is due to the transition (4)F9/2 → (4)I15/2. Spectrophotometric determinations of peaks were evaluated using the Commission Internationale de I'Eclairage (CIE) technique. The emission spectra were also observed using an infrared (IR) laser 980 nm source, and three distinct peaks were found in the IR region at 848, 870 and 980 nm. The prepared phosphor has utility for application in display devices. PMID:25810371

  4. Seismic Characterization of Fractured Reservoirs - Rock Physics Analysis and Modeling of James Limestone Reservoir

    NASA Astrophysics Data System (ADS)

    Sava, D. C.; Florez, J. M.; Mukerji, T.; Mavko, G.

    2002-12-01

    We present the rock physics analysis from well logs of the fractured James Limestone reservoir in the Neuville Field and also the results of our stochastic simulations of various seismic attributes for different models of fractures in the reservoir. Our goal is to determine the optimal combination of seismic attributes, and the uncertainty due to natural variability for delineating the gas filled fractured zones. Geological model based on the logs from horizontal wells suggests that the fractures are controlled by subseismic normal faults. These small faults can generate narrow zones with high fracture density. Between these fracture swarms, the background fracture density may correspond to regularly spaced, vertical joints. Therefore, for fracture modeling we consider both isotropic and anisotropic distributions of fractures. The isotropic distribution corresponds to the fracture swarms in the vicinity of faults, where the cracks are more or less randomly orientated, such as in brecciated zones. The anisotropic distribution corresponds to a single set of vertical joints that generates an azimuthally anisotropic medium with HTI symmetry. For each hypotheses of fracture distribution we stochastically model seismic interval and interface properties such as interval velocities, Poisson's Ratio, impedances, travel time, scattering attenuation, PP reflectivity as a function of angle of incidence and azimuth. The modeling shows that some of these attributes, such as Poisson's Ratio and P Impedance, are more sensitive to the presence of fractures than others. Rock physics analysis of the cross-dipole and FMI logs shows that the fractures are present especially in the clean limestone intervals, characterized by high velocity and small porosity. This observation can be used in fracture delineation from seismic measurements. In summary, rock physics fracture modeling and stochastic simulations for seismic attributes of James Lime reservoir provide a framework for delineating

  5. Combining rock physics and sedimentology for seismic reservoir characterization of North Sea turbidite systems

    NASA Astrophysics Data System (ADS)

    Avseth, Per Age

    The petroleum industry is increasing its focus on the exploration of reservoirs in turbidite systems. However, these sedimentary environments are often characterized by very complex sand distributions. Hence, reservoir description based on conventional seismic and well-log interpretation may be very uncertain. There is a need to employ more quantitative seismic techniques to reveal reservoirs units in these complex systems from seismic amplitude data. In this study we focus on North Sea turbidite systems. Our goal is to improve the ability to use 3D seismic data to map reservoirs in these systems. A cross-disciplinary methodology for seismic reservoir characterization is presented that combines rock physics, sedimentology, and statistical techniques. We apply this methodology to two turbidite systems of Paleocene age located in the South Viking Graben of the North Sea. First, we investigate the relationship between sedimentary petrography and rock physics properties. Next, we define seismic scale sedimentary units, referred to as seismic lithofacies. These facies represent populations of data that have characteristic geologic and seismic properties. We establish a statistically representative training database by identifying seismic lithofacies from thin-sections, cores, and well-log data. This procedure is guided by diagnostic rock physics modeling. Based on the training data, we perform multivariate classification of data from several wells in the area. Next, we assess uncertainties in amplitude versus offset (AVO) response related to the inherent natural variability of each seismic lithofacies. We generate bivariate probability density functions (pdfs) of two AVO parameters for different facies combinations. By combining the bivariate pdfs estimated from well-logs with the AVO parameters estimated from seismic data, we use both quadratic discriminant analysis and Bayesian classification to predict lithofacies and pore fluids from seismic amplitudes. The final

  6. CHARACTERIZATION AND MEASUREMENT OF INTRODCUTORY COLLEGE ASTRONOMY AND PHYSICS STUDENT UNDERSTANDING OF NEWTONIAN GRAVITY

    NASA Astrophysics Data System (ADS)

    Williamson, Kathryn

    2014-01-01

    The topic of Newtonian gravity offers a unique perspective from which to investigate and encourage conceptual change because it is something with which everyone has daily experience, and because it is taught in two courses that reach a variety of students - introductory college astronomy (‘Astro 101’) and physics (‘Phys 101’). Informed by the constructivist theory of learning, this study characterizes and measures Astro 101 and Phys 101 students’ understanding of Newtonian gravity within four conceptual domains - Directionality, Force Law, Independence of Other Forces, and Threshold. A phenomenographic analysis of student-supplied responses to open-ended questions about gravity resulted in characterization of students’ alternative models and misapplications of the scientific model. These student difficulties informed the development of a multiple-choice assessment instrument, the Newtonian Gravity Concept Inventory (NGCI). Classical Test Theory (CTT), student interviews, and expert review show that the NGCI is a reliable and valid tool for assessing both Astro 101 and Phys 101 students’ understanding of gravity. Furthermore, the NGCI can provide extensive and robust information about differences between Astro 101 and Phys 101 students and curricula. Comparing and contrasting CTT values and response patterns shows qualitative differences in each of the four conceptual domains. Additionally, performing an Item Response Theory (IRT) analysis calibrates item parameters for all Astro 101 and Phys 101 courses and provides Newtonian gravity ability estimates for each student. Physics students show significantly higher pre- and post-instruction IRT abilities than astronomy students, but they show approximately equal gains. Linear regression models that control for student characteristics and classroom dynamics show that: (1) differences in post-instruction abilities are most influenced by students’ pre-instruction abilities and the level of interactivity in

  7. Chemical and Physical Characterization of Collapsing Low-mass Prestellar Dense Cores

    NASA Astrophysics Data System (ADS)

    Hincelin, U.; Commerçon, B.; Wakelam, V.; Hersant, F.; Guilloteau, S.; Herbst, E.

    2016-05-01

    The first hydrostatic core, also called the first Larson core, is one of the first steps in low-mass star formation as predicted by theory. With recent and future high-performance telescopes, the details of these first phases are becoming accessible, and observations may confirm theory and even present new challenges for theoreticians. In this context, from a theoretical point of view, we study the chemical and physical evolution of the collapse of prestellar cores until the formation of the first Larson core, in order to better characterize this early phase in the star formation process. We couple a state-of-the-art hydrodynamical model with full gas-grain chemistry, using different assumptions for the magnetic field strength and orientation. We extract the different components of each collapsing core (i.e., the central core, the outflow, the disk, the pseudodisk, and the envelope) to highlight their specific physical and chemical characteristics. Each component often presents a specific physical history, as well as a specific chemical evolution. From some species, the components can clearly be differentiated. The different core models can also be chemically differentiated. Our simulation suggests that some chemical species act as tracers of the different components of a collapsing prestellar dense core, and as tracers of the magnetic field characteristics of the core. From this result, we pinpoint promising key chemical species to be observed.

  8. Physical and Mechanical Characterization of Electrodeposited Nickel Nanowires -- Influence of Current Density and External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Samykano, Mahendran

    Magnetic 1-D nanostructures have received great interest due to their various applications including high-density magnetic storage, sensors, drug delivery, and NEMS/MEMS systems. Among different 1-D nanostructures, magnetic nickel (Ni) nanowires with their ferromagnetic properties are of interest in such applications due to their lower cost, and they can be consistently synthesized via electrodeposition. While physical properties are influenced by processing parameters during electrodeposition of Ni nanowires, understanding of their influence on the mechanical properties is still not available. This is primarily due to the following challenges: tediousness involved in experimental techniques for mechanical characterization at nanoscale; sophisticated and careful experimentation required to be performed with advanced microscopy systems (SEM, AFM); robust nanoscale manipulators needed to place a single nanowire within the device; and difficulty in correctly loading and obtaining data for stress-strain within high powered microscopy environments. All of these factors pose significant challenges, limiting the current state of the art in mechanical characterization to its infancy, with wide differences in characterization curves and reported properties in this field. The present research and dissertation focuses on: 1. Experimental synthesis of electrodeposited Ni nanowires at different current densities and external magnetic fields, 2. Physical properties characterization of the synthesized nanowires to understand their morphology, structural and crystallographic properties, 3. Mechanical properties characterization of synthesized Ni nanowires through careful experiments within scanning electron microscope (SEM) based on uni-axial MEMS tensile loading device, 4. Data analysis to understand the process, physical and mechanical property interrelationship and to obtain insights on tensile deformation and failure modes observed in the Ni nanowires studied. Key research

  9. Rock-physics and seismic-inversion based reservoir characterization of the Haynesville Shale

    NASA Astrophysics Data System (ADS)

    Jiang, Meijuan; Spikes, Kyle T.

    2016-06-01

    Seismic reservoir characterization of unconventional gas shales is challenging due to their heterogeneity and anisotropy. Rock properties of unconventional gas shales such as porosity, pore-shape distribution, and composition are important for interpreting seismic data amplitude variations in order to locate optimal drilling locations. The presented seismic reservoir characterization procedure applied a grid-search algorithm to estimate the composition, pore-shape distribution, and porosity at the seismic scale from the seismically inverted impedances and a rock-physics model, using the Haynesville Shale as a case study. All the proposed rock properties affected the seismic velocities, and the combined effects of these rock properties on the seismic amplitude were investigated simultaneously. The P- and S-impedances correlated negatively with porosity, and the V P/V S correlated positively with clay fraction and negatively with the pore-shape distribution and quartz fraction. The reliability of these estimated rock properties at the seismic scale was verified through comparisons between two sets of elastic properties: one coming from inverted impedances, which were obtained from simultaneous inversion of prestack seismic data, and one derived from these estimated rock properties. The differences between the two sets of elastic properties were less than a few percent, verifying the feasibility of the presented seismic reservoir characterization.

  10. Characterizing physical habitats in rivers using map-derived drivers of fluvial geomorphic processes

    NASA Astrophysics Data System (ADS)

    Bizzi, Simone; Lerner, David N.

    2012-10-01

    New understanding of fluvial geomorphological processes has successfully informed flood mitigation strategies and rehabilitation schemes in recent years. However well established geomorphological assessments are location-specific and demanding in terms of resource and expertise required, and their routine application for regional or national river characterization, although desirable, is unlikely at present. This paper proposes a framework based on GIS procedures, empirical relationships and the self organized map for the analysis and classification of map-derived drivers of fluvial morphological processes. The geomorphic controls analysed are: channel gradient and hydrology, specific stream power, river order and floodplain extent. The case study is a gravel bed river in England. Using the self organized map, we analyse patterns of these controls along the river longitudinal profile and identify clusters of similar configuration. The reciprocal relationships that emerge amongst the geomorphic controls reflect the hierarchical nature of fluvial systems and are consistent with the current theoretical understanding of fluvial processes. Field observations from the River Habitat Survey are used to prove the influence of geomorphic drivers on reach-scale morphological forms. Six clusters are identified which describe six distinctive channel types. These proved to be characterized by distinctive configurations of geomorphic drivers and specific sets of physical habitat features. The method successfully characterizes the notable transitions in channel character along the river course. The framework is suitable for regional or national scale assessments through automatic GIS and statistical procedures with moderate effort.

  11. Review of Physics Related Research and Development Activities in Nondestructive Characterization of Solid Rocket Motor Materials

    NASA Astrophysics Data System (ADS)

    Pearson, Lee H.

    1998-10-01

    The perception that solid rocket motors (srm) are of relatively simple mechanical construction with a long history in private, military, and NASA applications may lead some to believe that little is left to be done in terms of basic and applied research and development in support of this technology. The fact is that srm?s are very complicated primarily because of the complexity of the materials from which they are built. The reliability and performance of srm?s are determined by the ballistic and mechanical properties of each individual material component, and by the manufacturing processes that conjoin these materials. In order to insure reliability and good performance, there are on-going materials research and development activities in the srm community. Included are activities involving the development of nondestructive evaluation (NDE) methods used for materials and processes characterization. Typical applications include: detection and characterization of defects in fiber reinforced composite materials, detection of weak bonds and debonds, verification of surface cleanliness prior to bonding, characterization of aging materials and bondlines, measurement of elastic properties in filled polymeric materials, monitoring of cure in polymeric materials, and measurement of film or coating thicknesses. NDE methods and physics principles upon which they are based will be described. Challenges and future research and development directions will be identified.

  12. Surface modification of MAl2O4:Eu2+,Dy3+ (M = Sr, Ca, Ba) phosphors to enhance water resistance by combustion method

    NASA Astrophysics Data System (ADS)

    Deng, Suqing; Xue, Zhiping; Yang, Qu; Liu, Yingliang; Lei, Bingfu; Xiao, Yong; Zheng, Mingtao

    2013-10-01

    A facile combustion method was introduced into surface modification of MAl2O4:Eu2+,Dy3+ (M = Sr, Ca, Ba) phosphors to improve their water resistance. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), pH measurements and photoluminescence (PL) spectrophotometry were used to characterize the phosphors before and after modification, respectively. Experimental results showed that compact layer of MAl2B2O7 (M = Sr, Ca, Ba) substance was formed on the surface of aluminate phosphors by direct chemical reaction between aluminate and boracic acid. MAl2B2O7 (M = Sr, Ca, Ba) substance is chemically stable in water and could improve water resistance of aluminate phosphors effectively with little influence of luminescence property. It was considered that the versatility of combustion method for surface modification of aluminate phosphors has been confirmed.

  13. Co-precipitation synthesis and luminescence properties of K2 TiF6 :Mn(4+) red phosphors for warm white light-emitting diodes.

    PubMed

    Liao, Jinsheng; Nie, Liling; Zhong, Laifu; Gu, Qingjie; Wang, Qi

    2016-05-01

    K2 TiF6 :Mn(4+) red phosphors with different Mn(4+) doping concentrations were obtained using the co-precipitation method. X-Ray diffraction, scanning electron microscopy, Raman spectra, Fourier transform infrared spectroscopy, photoluminescence excitation and emission spectra and decay curves were used to characterize the properties of K2 TiF6 :Mn(4+) phosphors. Under excitation at 470 nm, an intense red emission peak around 631 nm corresponding to the (2) Eg -(4) A2 transition of Mn(4+) was observed for 2.48 mol% K2 TiF6 :Mn(4+) phosphors and was used as the optimum doping concentration. The excellent luminescent properties of K2 TiF6 :Mn(4+) suggest that this material might be a promising red phosphor for generating warm white light in phosphor-converted white light-emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26387574

  14. Physical-chemical characterization of binary systems of metformin hydrochloride with triacetyl-beta-cyclodextrin.

    PubMed

    Corti, Giovanna; Capasso, Gaetano; Maestrelli, Francesca; Cirri, Marzia; Mura, Paola

    2007-11-01

    Interaction products of metformin hydrochloride (MF.HCl), an oral anti-hyperglycaemic agent highly soluble in water, with triacetyl-beta-cyclodextrin (TAbetaCyD), a hydrophobic CyD derivative practically insoluble in water, were prepared to evaluate their suitability for the development of a sustained-release dosage form of the drug. Equimolar MF.HCl-TAbetaCyD solid compounds were obtained by different techniques, i.e., physical mixing, kneading, co-grinding, sealed-heating, and spray-drying, in order to investigate and compare their effectiveness and influence on the physical-chemical properties of the final products. Differential scanning calorimetry, X-ray powder diffractometry, Fourier transform infrared spectroscopy and scanning electron microscopy were used for the solid-state characterization of the different MF.HCl-TAbetaCyD systems, whereas their in vitro dissolution properties were determined according to the dispersed amount method. According to the results of solid-state studies, the ability of the different preparation methods to promote effective interactions between drug and CyD varied in the order: spray-drying>co-grinding>kneading>sealed-heating approximately physical mixing. The same effectiveness rank order was observed also in dissolution studies. In fact the time to dissolve 100% drug varied increased from 1 min, for pure drug, to 3, 7, 40, 120 up to 420 min for physically mixed, sealed-heated, kneaded, co-ground and spray-dried products, respectively. Thus the drug-TA(CyD products obtained by spray drying and co-grinding were selected as the best candidates for the future development of a suitable prolonged-release oral dosage form of MF.HCl. PMID:17822867

  15. Sol-gel synthesized far-red chromium-doped garnet phosphors for phosphor-conversion light-emitting diodes that meet the photomorphogenetic needs of plants.

    PubMed

    Zabiliūtė, Akvilė; Butkutė, Skirmantė; Žukauskas, Artūras; Vitta, Pranciškus; Kareiva, Aivaras

    2014-02-10

    We report the sol-gel synthesis and characterization of far-red garnet phosphors Gd(3)Ga(5)O(12) (GGG:Cr), Y(3)Ga(5)O(12) (YGG:Cr), Lu(3)Ga(5)O(12) (LGG:Cr), and Gd(3)Sc(2)Ga(3)O(12) (GSGG:Cr) doped with different chromium (III) concentration (3, 5, and 8 mol. %). The morphological and luminescence properties of the phosphors annealed at different temperatures (1000°C, 1300°C, 1400°C, and 1500°C) were examined using x-ray diffraction, scanning electron microscopy, photoluminescence (PL), and PL excitation (PLE) spectroscopy, and by the measurements of diffuse reflection, PL internal quantum efficiency (QE), and PL decay time. The PLE spectra of the samples were found to peak at around 450 nm depending on the host, and luminescence was observed in the region of 700-760 nm. The QE was found to strongly depend on doping concentration and calcination temperature, and the PL decay exhibited biexponential behavior. The investigated far-red garnet phosphors, in particular GGG:Cr and YGG:Cr, show a potential for use in phosphor-converted light-emitting diodes that meet the photomorphogenetic needs of plants. PMID:24663271

  16. 40 CFR 721.10685 - Phosphoric acid, mixed esters (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid, mixed esters (generic... Specific Chemical Substances § 721.10685 Phosphoric acid, mixed esters (generic). (a) Chemical substance... phosphoric acid, mixed esters (PMN P-13-170) is subject to reporting under this section for the...

  17. 40 CFR 721.10431 - Phosphoric acid esters (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid esters (generic). 721... Substances § 721.10431 Phosphoric acid esters (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as phosphoric acid esters (PMNs...

  18. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid derivative (generic... Specific Chemical Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical substance... phosphoric acid derivative (PMN P-95-284) is subject to reporting under this section for the significant...

  19. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid derivative (generic... Specific Chemical Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical substance... phosphoric acid derivative (PMN P-95-284) is subject to reporting under this section for the significant...

  20. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Phosphoric acid derivative (generic... Specific Chemical Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical substance... phosphoric acid derivative (PMN P-95-284) is subject to reporting under this section for the significant...

  1. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphoric acid derivative (generic... Specific Chemical Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical substance... phosphoric acid derivative (PMN P-95-284) is subject to reporting under this section for the significant...

  2. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid derivative (generic... Specific Chemical Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical substance... phosphoric acid derivative (PMN P-95-284) is subject to reporting under this section for the significant...

  3. Red phosphors for use in high CRI fluorescent lamps

    DOEpatents

    Srivastava, Alok; Comanzo, Holly; Manivannan, Vankatesan; Setlur, Anant Achyut

    2005-11-15

    Novel red emitting phosphors for use in fluorescent lamps resulting in superior color rendering index values compared to conventional red phosphors. Also disclosed is a fluorescent lamp including a phosphor layer comprising blends of one or more of a blue phosphor, a blue-green phosphor, a green phosphor and a red a phosphor selected from the group consisting of SrY.sub.2 O.sub.4 :Eu.sup.3+, (Y,Gd)Al.sub.3 B.sub.4 O.sub.12 :Eu.sup.3+, and [(Y.sub.1-x-y-m La.sub.y)Gd.sub.x ]BO.sub.3 :Eu.sub.m wherein y<0.50 and m=0.001-0.3. The phosphor layer can optionally include an additional deep red phosphor and a yellow emitting phosphor. The resulting lamp will exhibit a white light having a color rendering index of 90 or higher with a correlated color temperature of from 2500 to 10000 Kelvin. The use of the disclosed red phosphors in phosphor blends of lamps results in high CRI light sources with increased stability and acceptable lumen maintenance over the course of the lamp life.

  4. 40 CFR 721.10431 - Phosphoric acid esters (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid esters (generic). 721... Substances § 721.10431 Phosphoric acid esters (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as phosphoric acid esters (PMNs...

  5. Physics.

    ERIC Educational Resources Information Center

    Bromley, D. Allan

    1980-01-01

    The author presents the argument that the past few years, in terms of new discoveries, insights, and questions raised, have been among the most productive in the history of physics. Selected for discussion are some of the most important new developments in physics research. (Author/SA)

  6. Physical structure characterization of theophylline in some acidic film-forming polymers.

    PubMed

    Sarisuta, N; Kumpugdee, M; Lawanprasert, P

    2000-06-01

    The physical structure and drug-polymer interactions of theophylline in Eudragit L100, shellac, polyvinyl acetate phthalate (PVAP), cellulose acetate phthalate (CAP), hydroxypropylmethylcellulose acetate phthalate (HPMCP), and hydroxypropylmethylcellulose (HPMC) were studied. The drug-polymer films were prepared by casting and were characterized using powder X-ray diffractometry (PXRD), nuclear magnetic resonance (NMR) spectroscopy, and thin-layer chromatography (TLC). Theophylline was found to recrystallize in the modification II form in all kinds of polymers, which was the same as that recrystallized solely from the solvent system and the original powder. The PXRD and NMR results indicated a superficial drug-polymer interaction between theophylline and Eudragit L100, while there was no evidence of interaction for the others. No drug decomposition was observed by TLC for all drug-polymer mixtures. PMID:10826118

  7. Physical vapour deposition of zirconia on titanium: fabrication, characterization and interaction with human osteoblast cells.

    PubMed

    Kaluđerović, Milena R; Mändl, Stephan; Kohlweyer, Hannes; Graf, Hans-Ludwig

    2015-12-01

    The physical vapor deposition of zirconia was used to prepare two new titanium-based surfaces M1 and M2 with a different layer thickness. These novel surfaces were characterized for chemistry, topography and morphology by surface and solid state techniques. Primary osteoblast cells were used for in vitro studies. DAPI assay was applied for cell proliferation, while for bone sialoprotein (BSP), osteonectin and transforming growth factor-β (TGF-β) expression immunohistochemical analyses were employed. Materials M1 and M2 affected cell proliferation accordingly to their surface roughness with their impact on cell number being between the impact of two rough (Ticer, SS) and two smooth surfaces (Ti cp and Cercon). Different influence of the investigated materials on the osteoblastic production of BSP (all materials similar impact), ON (Cercon-higher; SS-lower for others) and TGF-β (Cercon different) was found. PMID:26507200

  8. Physical characterization of the liquid adhesive from orb-weaving spiders.

    PubMed

    Torres, Fernando G; Troncoso, Omar P; Cavalie, Fernando

    2014-01-01

    Orb-weaving spiders produce bioadhesives that are used to capture their prey. In this paper, the physical properties of these adhesives are characterised. The liquid adhesive from Argiope argentata spiders has been studied and the morphological properties of the droplets, including size, shape and volume were determined. An estimation of viscosity and Young's modulus using atomic force microscopy has also been carried out. Morphological characterization confirmed that the liquid adhesive displayed a typical beads-on-a-string (BOAS) morphology on the silk fibres. The experimental data confirmed that the elastic modulus of the liquid adhesive from A. argentata was in the range 20-100kPa which is in agreement with the Dahlquist criterion for adhesives. PMID:24268267

  9. Simplified Models for a First Characterization of New Physics at the LHC

    SciTech Connect

    Alwall, Johan; Schuster, Philip; Toro, Natalia

    2009-06-19

    Low-energy SUSY and several other theories that address the hierarchy problem predict pair-production at the LHC of particles with Standard Model quantum numbers that decay to jets, missing energy, and possibly leptons. If an excess of such events is seen in LHC data, a theoretical framework in which to describe it will be essential to constraining the structure of the new physics. We propose a basis of four deliberately simplified models, each specified by only 2-3 masses and 4-5 branching ratios, for use in a first characterization of data. Fits of these simplified models to the data furnish a quantitative presentation of the jet structure, electroweak decays, and heavy-flavor content of the data, independent of detector effects. These fits, together with plots comparing their predictions to distributions in data, can be used as targets for describing the data within any full theoretical model.

  10. Physical and optical characterization of Er3+ doped lead-zinc-borate glass.

    PubMed

    Sooraj Hussain, N; Cardoso, P J; Hungerford, G; Gomes, M J M; Ali, Nasar; Santos, J D; Buddhudu, S

    2009-06-01

    This paper reports on the systematic optical characterization of Er3+ (1.0%) doped lead-zinc-borate glass from the measured absorption, luminescence and fluorescence lifetime decay curve profiles. By the application of the Judd-Ofelt theory, spectral intensities of the absorption bands have been analysed and these absorption results have been used in evaluating the luminescence properties of the Er3+ doped lead-zinc-borate glass. Stimulated emission cross-sections (sigmapE) of the measured emission transitions have been computed. Based on the measured glass density, and refractive indices, other related physical parameters have also been evaluated. Further, the structural and morphology of the glass material have also been investigated from X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy analysis. PMID:19504881

  11. Full scale phosphoric acid fuel cell stack technology development

    NASA Technical Reports Server (NTRS)

    Christner, L.; Faroque, M.

    1984-01-01

    The technology development for phosphoric acid fuel cells is summarized. The preparation, heat treatment, and characterization of carbon composites used as bipolar separator plates are described. Characterization included resistivity, porosity, and electrochemical corrosion. High density glassy carbon/graphite composites performed well in long-term fuel cell endurance tests. Platinum alloy cathode catalysts and low-loaded platinum electrodes were evaluated in 25 sq cm cells. Although the alloys displayed an initial improvement, some of this improvement diminished after a few thousand hours of testing. Low platinum loading (0.12 mg/sq cm anodes and 0.3 mg/sq cm cathodes) performed nearly as well as twice this loading. A selectively wetproofed anode backing paper was tested in a 5 by 15 inch three-cell stack. This material may provide for acid volume expansion, acid storage, and acid lateral distribution.

  12. Effect of Composition and Impurities on the Phosphorescence of Green-Emitting Alkaline Earth Aluminate Phosphor

    PubMed Central

    Kim, Doory; Kim, Han-Eol; Kim, Chang-Hong

    2016-01-01

    Recent improvements to SrAl2O4:Eu2+, Dy3+ phosphors have enabled the use of luminescent hosts with a stable crystal structure and high physical and chemical stability, thus overcoming the bottleneck in the applicability of ZnS:Cu phosphors. However, enhancement of afterglow lifetime and brightness in SrAl2O4:Eu2+, Dy3+ phosphors remains a challenging task. Here, we have improved the afterglow characteristics in terms of persistence time and brightness by a systematic investigation of the composition of Eu-doped alkaline earth aluminate SrAl2O4:Eu2+, Dy3+ crystals. We found that a Dy3+/Eu2+ ratio of ~2.4 and ~0.935 mol Eu2+ (per mol of SrAl2O4) gave the brightest and longest emissions (11% and 9% increase for each). Doping with Si4+ also resulted in a slight increase in brightness up to ~15%. Doping with alkali metal or alkaline earth metal significantly enhanced the phosphorescence intensity. In particular, doping with 0.005 mol Li+ (per mol of SrAl2O4) alone boosted the phosphorescence intensity to 239% of the initial value, as compared to that observed for the non-doped crystal, while doping with 0.01 mol Mg2+ and 0.005 mol Li+ (per 1 mol SrAl2O4) boosted the phosphorescence intensity up to 313% of the initial value. The results of this investigation are expected to act as a guideline for the synthesis of bright and long persistent phosphors, and facilitate the development of persistent phosphors with afterglow characteristics superior to those of conventional phosphors. PMID:26731086

  13. Effect of Composition and Impurities on the Phosphorescence of Green-Emitting Alkaline Earth Aluminate Phosphor.

    PubMed

    Kim, Doory; Kim, Han-Eol; Kim, Chang-Hong

    2016-01-01

    Recent improvements to SrAl2O4:Eu2+, Dy3+ phosphors have enabled the use of luminescent hosts with a stable crystal structure and high physical and chemical stability, thus overcoming the bottleneck in the applicability of ZnS:Cu phosphors. However, enhancement of afterglow lifetime and brightness in SrAl2O4:Eu2+, Dy3+ phosphors remains a challenging task. Here, we have improved the afterglow characteristics in terms of persistence time and brightness by a systematic investigation of the composition of Eu-doped alkaline earth aluminate SrAl2O4:Eu2+, Dy3+ crystals. We found that a Dy3+/Eu2+ ratio of ~2.4 and ~0.935 mol Eu2+ (per mol of SrAl2O4) gave the brightest and longest emissions (11% and 9% increase for each). Doping with Si4+ also resulted in a slight increase in brightness up to ~15%. Doping with alkali metal or alkaline earth metal significantly enhanced the phosphorescence intensity. In particular, doping with 0.005 mol Li+ (per mol of SrAl2O4) alone boosted the phosphorescence intensity to 239% of the initial value, as compared to that observed for the non-doped crystal, while doping with 0.01 mol Mg2+ and 0.005 mol Li+ (per 1 mol SrAl2O4) boosted the phosphorescence intensity up to 313% of the initial value. The results of this investigation are expected to act as a guideline for the synthesis of bright and long persistent phosphors, and facilitate the development of persistent phosphors with afterglow characteristics superior to those of conventional phosphors. PMID:26731086

  14. Understanding fine sediment and phosphorous delivery in upland catchments

    NASA Astrophysics Data System (ADS)

    Perks, M. T.; Reaney, S. M.

    2013-12-01

    The uplands of UK are heavily impacted by land management including; farming and forestry operations, moorland burning, peat extraction, metal mining, artificial drainage and channelisation. It has been demonstrated that such land management activity may modify hillslope processes, resulting in enhanced runoff generation and changing the spatial distribution and magnitude of erosion. Resultantly, few upland river systems of the UK are operating in a natural state, with land management activity often resulting in increased fluxes of suspended sediment (< 2 mm) and associated pollutants (such as phosphorous). Most recent Environment Agency (EA) data reveals that 60% of monitored water bodies within upland areas of the UK are currently at risk of failing the Water Framework Directive (WFD) due to poor ecological status. In order to prevent the continual degradation of many upland catchments, riverine systems and their diverse ecosystems, a range of measures to control diffuse pollution will need to be implemented. Future mitigation options and measures in the UK may be tested and targeted through the EA's catchment pilot scheme; DEFRA's Demonstration Test Catchment (DTC) programmes and through the catchment restoration fund. However, restoring the physical and biological processes of past conditions in inherently sensitive upland environments is extremely challenging requiring the development of a solid evidence base to determine the effectiveness of resource allocation and to enable reliable and transparent decisions to be made about future catchment operations. Such evidence is rarely collected, with post-implementation assessments often neglected. This paper presents research conducted in the Morland sub-catchment of the River Eden within Cumbria; UK. 80% of this headwater catchment is in upland areas and is dominated by improved grassland and rough grazing. The catchment is heavily instrumented with a range of hydro-meteorological equipment. A high-tech monitoring

  15. Luminescence and afterglow in Sr{sub 2}SiO{sub 4}:Eu{sup 2+}, RE{sup 3+} [RE = Ce, Nd, Sm and Dy] phosphors-Role of co-dopants in search for afterglow

    SciTech Connect

    Lakshminarasimhan, N. Varadaraju, U.V.

    2008-11-03

    Luminescence of Eu{sup 2+} in Sr{sub 2}SiO{sub 4}:Eu{sup 2+}, RE{sup 3+} [RE = Ce, Nd, Sm and Dy] phosphors was studied with a view to obtain an afterglow phosphor. The synthesized phosphors were characterized by powder X-ray diffraction (XRD), diffuse reflectance, photo- and thermoluminescence spectroscopic techniques. Afterglow was observed only with Dy{sup 3+} co-doped phosphor. The observed afterglow with Dy{sup 3+} co-doping originated from the formation of suitable traps which was supported by thermoluminescence results.

  16. Preparation and characterization of physically modified glass beads used as model carriers in dry powder inhalers.

    PubMed

    Zellnitz, Sarah; Redlinger-Pohn, Jakob Dominik; Kappl, Michael; Schroettner, Hartmuth; Urbanetz, Nora Anne

    2013-04-15

    The aim of this work is the physical modification and characterization of the surface topography of glass beads used as model carriers in dry powder inhalers (DPIs). By surface modification the contact area between drug and carrier and thereby interparticle forces may be modified. Thus the performance of DPIs that relies on interparticle interactions may be improved. Glass beads were chosen as model carriers because various prospects of physical surface modification may be applied without affecting other factors also impacting interparticle interactions like particle size and shape. To generate rough surfaces glass beads were processed mechanically by friction and impaction in a ball mill with different grinding materials that were smaller and harder with respect to the glass beads. By varying the grinding time (4 h, 8 h) and by using different grinding media (tungsten carbide, quartz) surfaces with different shades of roughness were generated. Depending on the hardness of the grinding material and the grinding time the surface roughness was more or less pronounced. Surface roughness parameters and specific surface area were determined via several complementary techniques in order to get an enhanced understanding of the impact of the modifying procedure on the surface properties of the glass beads. PMID:23470233

  17. Characterization of wave physics in acoustic metamaterials using a fiber optic point detector

    NASA Astrophysics Data System (ADS)

    Ganye, Randy; Chen, Yongyao; Liu, Haijun; Bae, Hyungdae; Wen, Zhongshan; Yu, Miao

    2016-06-01

    Due to limitations of conventional acoustic probes, full spatial field mapping (both internal and external wave amplitude and phase measurements) in acoustic metamaterials with deep subwavelength structures has not yet been demonstrated. Therefore, many fundamental wave propagation phenomena in acoustic metamaterials remain experimentally unexplored. In this work, we realized a miniature fiber optic acoustic point detector that is capable of omnidirectional detection of complex spatial acoustic fields in various metamaterial structures over a broadband spectrum. By using this probe, we experimentally characterized the wave-structure interactions in an anisotropic metamaterial waveguide. We further demonstrated that the spatial mapping of both internal and external acoustic fields of metamaterial structures can help obtain important wave propagation properties associated with material dispersion and field confinement, and develop an in-depth understanding of the waveguiding physics in metamaterials. The insights and inspirations gained from our experimental studies are valuable not only for the advancement of fundamental metamaterial wave physics but also for the development of functional metamaterial devices such as acoustic lenses, waveguides, and sensors.

  18. Physical-chemical and biological characterization of silk fibroin-coated porous membranes for medical applications.

    PubMed

    Cassinelli, C; Cascardo, G; Morra, M; Draghi, L; Motta, A; Catapano, G

    2006-09-01

    Membranes in artificial organs and scaffolds for tissue engineering are often coated with biomimetic molecules (e.g., collagen) to improve their biocompatibility and promote primary cell adhesion and differentiation. However, animal proteins are expensive and may be contaminated with prions. Silk fibroin (SF) made by Bombyx Mori silk worms, used as a scaffold or grafted to other polymers, reportedly promotes the adhesion and growth of many human cell types. This paper describes how commercial porous membranes were physically coated with SF, and their physical-chemical properties were characterized by SEM, AFM, tensile stress analysis and dynamic contact angle measurements. The effect of the SF coating on membrane biocompatibility and resistance to bacterial colonization is also examined. The proposed technique yields SF coats of different thickness that strengthen the membranes and make their surface remarkably more wettable. The SF coat is not cytotoxic, and promotes the adhesion and proliferation of an immortalized fibroblast cell line. Similarly to collagen, SF-coated membranes also exhibit a much better resistance to the adhesion of S. epidermidis bacteria than uncoated membranes. These preliminary results suggest that SF is a feasible alternative to collagen as a biomimetic coating for 3D scaffolds for tissue engineering or bioartificial (as well as artificial) prosthesis. PMID:17033996

  19. Characterization of Physically and Chemically Separated Athabasca Asphaltenes Using Small-Angle X-ray Scattering

    SciTech Connect

    Amundaraín Hurtado, Jesús Leonardo; Chodakowski, Martin; Long, Bingwen; Shaw, John M.

    2012-02-07

    Athabasca asphaltenes were characterized using small-angle X-ray scattering (SAXS). Two methods were used to separate asphaltenes from the Athabasca bitumen: namely, chemical separation by precipitation with n-pentane and physical separation by nanofiltration using a zirconia membrane with a 20 nm average pore size. The permeate and chemically separated samples were diluted in 1-methylnaphtalene and n-dodecane prior to SAXS measurements. The temperature and asphaltene concentration ranges were 50-310 C and 1-10.4 wt %, respectively. Model-independent analysis of SAXS data provided the radius of gyration and the scattering coefficients. Model-dependent fits provided size distributions for asphaltenes assuming that they are dense and spherical. Model-independent analysis for physically and chemically separated asphaltenes showed significant differences in nominal size and structure, and the temperature dependence of structural properties. The results challenge the merits of using chemically separated asphaltene properties as a basis for asphaltene property prediction in hydrocarbon resources. While the residuals for model-dependent fits are small, the results are inconsistent with the structural parameters obtained from model-independent analysis.

  20. A physical sciences network characterization of circulating tumor cell aggregate transport

    PubMed Central

    King, Michael R.; Phillips, Kevin G.; Mitrugno, Annachiara; Lee, Tae-Rin; de Guillebon, Adelaide M. E.; Chandrasekaran, Siddarth; McGuire, Matthew J.; Carr, Russell T.; Baker-Groberg, Sandra M.; Rigg, Rachel A.; Kolatkar, Anand; Luttgen, Madelyn; Bethel, Kelly; Kuhn, Peter; Decuzzi, Paolo

    2015-01-01

    Circulating tumor cells (CTC) have been implicated in the hematogenous spread of cancer. To investigate the fluid phase of cancer from a physical sciences perspective, the multi-institutional Physical Sciences-Oncology Center (PS-OC) Network performed multidisciplinary biophysical studies of single CTC and CTC aggregates from a patient with breast cancer. CTCs, ranging from single cells to aggregates comprised of 2–5 cells, were isolated using the high-definition CTC assay and biophysically profiled using quantitative phase microscopy. Single CTCs and aggregates were then modeled in an in vitro system comprised of multiple breast cancer cell lines and microfluidic devices used to model E-selectin mediated rolling in the vasculature. Using a numerical model coupling elastic collisions between red blood cells and CTCs, the dependence of CTC vascular margination on single CTCs and CTC aggregate morphology and stiffness was interrogated. These results provide a multifaceted characterization of single CTC and CTC aggregate dynamics in the vasculature and illustrate a framework to integrate clinical, biophysical, and mathematical approaches to enhance our understanding of the fluid phase of cancer. PMID:25788574

  1. Photoluminescence properties of a new orange-red emitting Sm3+-doped Y2Mo4O15 phosphor

    NASA Astrophysics Data System (ADS)

    Deng, Huajuan; Zhao, Ze; Wang, Jing; Hei, Zhoufei; Li, Mengxue; Noh, Hyeon Mi; Jeong, Jung Hyun; Yu, Ruijin

    2015-08-01

    A series of novel Y2Mo4O15:xSm3+ ((0.01 ≤ x ≤ 0.20) phosphors for white light-emitting (W-LEDs) were successfully prepared by the solid state reaction technology at 973 K for 12 h. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of the as-synthesized phosphors. The emission spectra of the Y2Mo4O15:Sm3+ phosphors consisted of some sharp emission peaks of Sm3+ ions centered at 565 nm, 605 nm, 650 nm, and 712 nm. The strongest one is located at 605 nm due to 4G5/2-6H7/2 transition of Sm3+, generating bright orange-red light. The optimum dopant concentration of Sm3+ ions in Y2Mo4O15:xSm3+ is around 5 mol% and the critical transfer distance of Sm3+ is calculated as 23.32 Å. The CIE chromaticity coordinates of the Y2Mo4O15:0.05Sm3+ phosphors were located in the orange reddish region. The Y2Mo4O15:Sm3+ phosphors may be potentially used as red phosphors for white light-emitting diodes.

  2. Structural and luminescence properties of Y(2-x)GeMoO8:REx (RE = Eu, Tb) phosphors.

    PubMed

    Li, Naixu; Zhou, Jiancheng; Sun, Yueming

    2014-08-01

    Y(2-x)GeMoO8:REx (RE = Eu, Tb) phosphors were synthesized using a facile sol-gel method. The morphology and structure of the phosphors were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD); while their luminescent properties were investigated by photoluminescence (PL) spectrometry. Our results reveal that all of these Y(2-x)GeMoO8:REx (RE = Eu, Tb) phosphors adopted the tetragonal phase, belonging to Scheelite (CaWO4 ) structure. The obtained YGeMoO8:Eu phosphors exhibit a strong emission in the red light range which can be assigned to the (5)D0  → (7)F2 transition of Eu(3+) when it is excited at 459 nm. Under 392 and 489 nm excitation, the YGeMoO8:Tb phosphors present predominant green emission ((5)D4  → (7)F5) at 540 nm. The highest emission of the phosphors can be achieved by adjusting the doping concentration to be 0.25 for Eu(3+) and 0.15 for Tb(3+), respectively. The promising luminescence properties of these materials indicate that they can be potentially applied to white-light-emitting diodes. PMID:23832824

  3. Effect of variable cerium concentration on photoluminescence behaviour in ZrO2 phosphor synthesized by combustion synthesis method

    NASA Astrophysics Data System (ADS)

    Dubey, Vikas; Kaur, Jagjeet

    2016-05-01

    Present paper reports synthesis and characterization of trivalent cerium (Ce3+) doped zirconium dioxide (ZrO2) phosphors. Effect of variable concentration of cerium on photoluminescence (PL) is studied. Samples were prepared by combustion synthesis technique which is suitable for less time taking techniques also for large scale production for phosphors. Starting material used for sample preparation are Zr(NO3)3 and Ce(NO3)3 and urea used as a fuel. All prepared phosphor with variable concentration of Ce3+ (0.1 to 2mol%) was studied by photoluminescence analysis it is found that the excitation spectra of prepared phosphor shows broad excitation centred at 390nm. The excitation spectra with variable concentration of Ce3+ show strong peaks at 447nm. Spectrophotometric determinations of peaks are evaluated by Commission Internationale de I'Eclairage technique. Using this phosphor, the desired CIE values including emissions throughout the violet (390 nm) and blue (427 nm) of the spectra were achieved. Efficient blue light emitting diodes were fabricated using Ce3+ doped phosphor based on near ultraviolet (NUV) excited LED lights.

  4. Physical characterization of cadmium telluride/cadmium sulfide photovoltaics: Defects, fields, and micrononuniformities

    NASA Astrophysics Data System (ADS)

    Shvydka, Diana

    Recent advances in large area thin-film photovoltaic manufacturing have raised a number of problems related to the physical parameters and processes behind the device efficiency and stability. The characteristics of interest include the defect spectra and related optical absorption, the built-in electric field distribution, the degree of lateral uniformity of the device, and the device stability. Established in this thesis is a set of techniques appropriate for the physical characterization of the above features in CdTe/CdS solar cells, addressing the issues of device spectra vs. energy (as revealed in the optical absorption, photoluminescence (PL), and admittance spectroscopy); the electric field distribution analyzed by means of bias dependent PL, and, indirectly, by capacitance measurements; device lateral resistivity and uniformity, through the phenomenon of nonlocal optical response and PL mapping; local parameter fluctuations as appear in virtually all of the above cases. The most important physical conclusions made are: energy spectra of polycrystalline CdTe based photovoltaics combine the features of crystalline materials, such as identifiable point defects, and amorphous materials, which exhibit continuous spectra of localized states; the concept of a single-defect (elemental) capacitance is for the first time defined and applied to estimate the density of states in polycrystalline p-n junctions; a phenomenon of bias-dependent PL in CdTe based photovoltaics is for the first time observed and modeled; a new phenomenon of nonlocal photovoltaic response is observed and interpreted. The results suggest several practical applications, such as: absorption and PL measurements as a diagnostic tool for monitoring the CdCl2, quality of treatments; admittance spectroscopy techniques to diagnose the material quality and degradation through its defect spectra and concentration; bias-dependent PL as a sensitive nondestructive accelerated life testing tool; nonlocal PV

  5. Aerosol Chemical and Physical Characterization in Central Amazonia during the 2013 Dry Season

    NASA Astrophysics Data System (ADS)

    Artaxo, P.; Stern, R.; Brito, J.; Carbone, S.

    2015-12-01

    During the dry season, the central Amazon forest is highly influenced by forest fires transported through large distances, changing drastically the atmospheric composition even in remote places. This work focuses on a physical-chemical characterization of the aerosol population over a pristine site in Central Amazonia during the dry season. The submicrometer organic aerosols were measured with the Aerodyne ACSM (Aerosol Chemical Speciation Monitor, Aerodyne Inc). Optical properties, size distribution and other micro-physical characteristics were also analyzed. Other instruments were simultaneously used. The measurements were taken during the dry season of 2013 in the Cuieiras ecological reserve (ZF2), northwest of Manaus. The statistical analysis of the data was done with the PMF (Positive Matrix Factorization) technique, in which the organic aerosol was separated into different factors, and then its sources and forming processes were attributed. Results show that the mean aerosol loading was 5,91 μg m-3, from which 78% are of organic composition, 8.5% are sulfate, 6.5% are equivalent black carbon, 4% are ammonium and 3% are nitrate. The mass spectra variability can be explained by 3 factors only, determined with the PMF technique. They were identified as BBOA (Biomass Burning Organic Aerosol), representing 12% of the total organic mass, OOA (Oxygenated Organic Aerosol), representing 66% of the total organic mass and IEPOX-SOA (Isoprene derived Epoxydiol-Secondary Organic Aerosol), representing 21% of the total organic mass. Even in remote and pristine regions, Central Amazonia is highly impacted by biomass burning. Biogenic secondary organic aerosols are also present during the dry season, and the suppression of its wet deposition processes increases their concentration. The oxidation level and other physical-chemical characteristics indicate that the long range transport is responsible for the regional range of this impact.

  6. Bio- chemical and physical characterizations of mesenchymal stromal cells along the time course of directed differentiation

    PubMed Central

    Chen, Yin-Quan; Liu, Yi-Shiuan; Liu, Yu-An; Wu, Yi-Chang; del Álamo, Juan C.; Chiou, Arthur; Lee, Oscar K.

    2016-01-01

    Cellular biophysical properties are novel biomarkers of cell phenotypes which may reflect the status of differentiating stem cells. Accurate characterizations of cellular biophysical properties, in conjunction with the corresponding biochemical properties could help to distinguish stem cells from primary cells, cancer cells, and differentiated cells. However, the correlated evolution of these properties in the course of directed stem cells differentiation has not been well characterized. In this study, we applied video particle tracking microrheology (VPTM) to measure intracellular viscoelasticity of differentiating human mesenchymal stromal/stem cells (hMSCs). Our results showed that osteogenesis not only increased both elastic and viscous moduli, but also converted the intracellular viscoelasticity of differentiating hMSCs from viscous-like to elastic-like. In contrast, adipogenesis decreased both elastic and viscous moduli while hMSCs remained viscous-like during the differentiation. In conjunction with bio- chemical and physical parameters, such as gene expression profiles, cell morphology, and cytoskeleton arrangement, we demonstrated that VPTM is a unique approach to quantify, with high data throughput, the maturation level of differentiating hMSCs and to anticipate their fate decisions. This approach is well suited for time-lapsed study of the mechanobiology of differentiating stem cells especially in three dimensional physico-chemical biomimetic environments including porous scaffolds. PMID:27526936

  7. Physical-Chemical Characterization and Formulation Considerations for Solid Lipid Nanoparticles.

    PubMed

    Chauhan, Harsh; Mohapatra, Sarat; Munt, Daniel J; Chandratre, Shantanu; Dash, Alekha

    2016-06-01

    Pure glyceryl mono-oleate (GMO) (lipid) and different batches of GMO commonly used for the preparation of GMO-chitosan nanoparticles were characterized by modulated differential scanning calorimetry (MDSC), cryo-microscopy, and cryo-X-ray powder diffraction techniques. GMO-chitosan nanoparticles containing poloxamer 407 as a stabilizer in the absence and presence of polymers as crystallization inhibitors were prepared by ultrasonication. The effect of polymers (polyvinyl pyrrolidone (PVP), Eudragits, hydroxyl propyl methyl cellulose (HPMC), polyethylene glycol (PEG)), surfactants (poloxamer), and oils (mineral oil and olive oil) on the crystallization of GMO was investigated. GMO showed an exothermic peak at around -10°C while cooling and another exothermic peak at around -12°C while heating. It was followed by two endothermic peaks between 15 and 30 C, indicative of GMO melting. The results are corroborated by cryo-microscopy and cryo-X-ray. Significant differences in exothermic and endothermic transition were observed between different grades of GMO and pure GMO. GMO-chitosan nanoparticles resulted in a significant increase in particle size after lyophilization. MDSC confirmed that nanoparticles showed similar exothermic crystallization behavior of lipid GMO. MDSC experiments showed that PVP inhibits GMO crystallization and addition of PVP showed no significant increase in particle size of solid lipid nanoparticle (SLN) during lyophilization. The research highlights the importance of extensive physical-chemical characterization for successful formulation of SLN. PMID:26292931

  8. Bio- chemical and physical characterizations of mesenchymal stromal cells along the time course of directed differentiation.

    PubMed

    Chen, Yin-Quan; Liu, Yi-Shiuan; Liu, Yu-An; Wu, Yi-Chang; Del Álamo, Juan C; Chiou, Arthur; Lee, Oscar K

    2016-01-01

    Cellular biophysical properties are novel biomarkers of cell phenotypes which may reflect the status of differentiating stem cells. Accurate characterizations of cellular biophysical properties, in conjunction with the corresponding biochemical properties could help to distinguish stem cells from primary cells, cancer cells, and differentiated cells. However, the correlated evolution of these properties in the course of directed stem cells differentiation has not been well characterized. In this study, we applied video particle tracking microrheology (VPTM) to measure intracellular viscoelasticity of differentiating human mesenchymal stromal/stem cells (hMSCs). Our results showed that osteogenesis not only increased both elastic and viscous moduli, but also converted the intracellular viscoelasticity of differentiating hMSCs from viscous-like to elastic-like. In contrast, adipogenesis decreased both elastic and viscous moduli while hMSCs remained viscous-like during the differentiation. In conjunction with bio- chemical and physical parameters, such as gene expression profiles, cell morphology, and cytoskeleton arrangement, we demonstrated that VPTM is a unique approach to quantify, with high data throughput, the maturation level of differentiating hMSCs and to anticipate their fate decisions. This approach is well suited for time-lapsed study of the mechanobiology of differentiating stem cells especially in three dimensional physico-chemical biomimetic environments including porous scaffolds. PMID:27526936

  9. Phosphor suspended in silicone, molded/formed and used in a remote phosphor configuration

    SciTech Connect

    Kolodin, Boris; Deshpande, Anirudha R

    2014-09-16

    A light emitting package comprising a support hosting at least one light emitting diode. A light transmissive dome comprised of a silicone including a phosphor material positioned to receive light emitted by the diode. A glass cap overlies said dome.

  10. Experimental characterization and modeling of isothermal and nonisothermal physical aging in glassy polymer films

    NASA Astrophysics Data System (ADS)

    Guo, Yunlong

    This dissertation focuses on nonisothermal physical aging of polymers from both experimental and theoretical aspects. The study concentrates on pure polymers rather than fiber-reinforced composites; this step removes several complicating factors to simplify the study. It is anticipated that the findings of this work can then be applied to composite materials applications. The physical aging tests in this work are performed using a dynamic mechanical analyzer (DMA). The viscoelastic response of glassy polymers under various loading and thermal histories are observed as stress-strain data at a series of time points. The first stage of the experimental work involves the characterization of the isothermal physical aging behavior of two advanced thermoplastics. The second stage conducts tests on the same materials with varying thermal histories and with long-term test duration. This forms the basis to assess and modify a nonisothermal physical aging model (KAHR-ate model). Based on the experimental findings, the KAHR-ate model has been revised by new correlations between aging shift factors and volume response; this revised model performed well in predicting the nonisothermal physical aging behavior of glassy polymers. In the work on isothermal physical aging, short-term creep and stress relaxation tests were performed at several temperatures within 15-35°C below the glass transition temperature (Tg) at various aging times, using the short-term test method established by Struik. Stress and strain levels were such that the materials remained in the linear viscoelastic regime. These curves were then shifted together to determine momentary master curves and shift rates. In order to validate the obtained isothermal physical aging behavior, the results of creep and stress relaxation testing were compared and shown to be consistent with one another using appropriate interconversion of the viscoelastic material functions. Time-temperature superposition of the master curves

  11. Characterization of physical activity and sitting time among patients on hemodialysis using a new physical activity instrument

    PubMed Central

    Johansen, Kirsten L.; Painter, Patricia; Delgado, Cynthia; Doyle, Julie

    2014-01-01

    Objective Physical activity questionnaires usually focus on moderate to vigorous activities and may not accurately capture physical activity or variation in levels of activity among extremely inactive groups like dialysis patients. Design Cross-sectional study Setting Three dialysis facilities in the San Francisco Bay Area Subjects 68 prevalent hemodialysis patients Intervention We administered a new physical activity questionnaire designed to capture activity in the lower end of the range, the Low Physical Activity Questionnaire (LoPAQ). Main Outcome Measure Outcome measures were correlation with a validated physical activity questionnaire, the Minnesota Leisure Time Activity (LTA) questionnaire and with self-reported physical function (Physical Function score of the SF-36) and physical performance (gait speed, chair stand, balance, and Short Physical Performance Battery [SPPB]) . We also determined whether patients who were frail or reported limitations in activities of daily living (ADL) were less active on the LoPAQ. Results 68 participants (mean age 59 ± 14 years, 59% men) completed the study. Patients were inactive according to the LoPAQ, with a median (IQR) of 517 (204 – 1190) kcal/week of physical activity. Although activity from the LTA was lower than on the LoPAQ (411 (61 – 902) kcal/week), the difference was not statistically significant (p=0.20), and results from the two instruments were strongly correlated (rho =0.62, p < 0.001). In addition, higher physical activity measured by the LoPAQ was correlated with better self-reported functioning (rho = 0.64, p < 0.001), better performance on gait speed (rho = 0.32, p=0.02), balance (rho = 0.45, p < 0.001), and chair rising (rho = −0.32, p=0.03) tests and with higher SPPB total score (rho = 0.51, p < 0.001). Frail patients and patients with ADL limitations were less active than those who were not frail or limited. Conclusion The LoPAQ performed similarly to the Minnesota LTA questionnaire in our

  12. Physical property characterization of a damage zone in granitic rock - Implications for geothermal reservoir properties

    NASA Astrophysics Data System (ADS)

    Wenning, Quinn; Madonna, Claudio; Amann, Florian; Gischig, Valentin; Burg, Jean-Pierre

    2016-04-01

    Geothermal energy offers a viable alternative to mitigate greenhouse gas emitting energy production. A tradeoff between less expensive drilling costs and increased permeability at shallow depths versus increased heat production at deeper depths stipulates the economic energy potential of a given reservoir. From a geological perspective, successful retrieval of geothermal energy from the subsurface requires sufficient knowledge of the structural and stratigraphic relationship of the target formations, which govern the thermal conditions, physical properties, and fluid flow properties of reservoir rocks. In Switzerland, deep basement rocks (~5 km) with fluid conducting damage zones and enhanced fractured systems stimulated by hydraulic shearing are seen as a potential geothermal reservoir system. Damage zones, both natural and induced, provide permeability enhancement that is especially important for creating fluid conductivity where the matrix permeability is low. This study concentrates on characterizing the elastic and transport properties entering into a natural damage zone penetrated by a borehole at the Grimsel underground research laboratory. The borehole drilled from a cavern at 480 m below ground surface penetrates approximately 20 m of mostly intact Grimsel granodiorite before entering the first phyllosilicate-rich shear zone (~0.2 m thick). The borehole intersects a second shear zone at approximately 23.8m. Between the two shear zones the Grimsel granodiorite is heavily fractured. The minimum principle stress magnitude from in-situ measurements decreases along the borehole into the first shear zone. Two mutually perpendicular core samples of Grimsel granodiorite were taken every 0.1 m from 19.5 to 20.1 m to characterize the physical properties and anisotropy changes as a gradient away from the damage zone. Measurements of ultrasonic compressional (Vp) and shear (Vs) velocities at 1 MHz frequency are conducted at room temperature and hydrostatic pressures

  13. Physical characterization of a watershed through GIS: a study in the Schmidt stream, Brazil.

    PubMed

    Reis, D R; Plangg, R; Tundisi, J G; Quevedo, D M

    2015-12-01

    Remote sensing and geoprocessing are essential tools for obtaining and maintaining records of human actions on space over the course of time; these tools offer the basis for diagnoses of land use, environmental interference and local development. The Schmidt stream watershed, located in the Sinos River basin, in southern Brazil, has an environmental situation similar to that of the majority of small streams draining rural and urban areas in southern Brazil: agricultural and urbanization practices do not recognize the riparian area and there is removal of original vegetation, disregarding the suitability of land use; removal of wetlands; intensive water use for various activities; and lack of control and monitoring in the discharge of wastewater, among other factors, deteriorate the quality of this important environment.This article aims to achieve a physical characterization of the Schmidt stream watershed (Sinos river basin) identifying elements such as land use and occupation, soil science, geology, climatology, extent and location of watershed, among others, so as to serve as the basis for a tool that helps in the integrated environmental management of watersheds. By applying geographic information system - GIS to the process of obtaining maps of land use and occupation, pedologicaland geological, and using climatological data from the Campo Bom meteorological station, field visit, review of literature and journals, and publicly available data, the physical characterization of the Schmidt stream watershed was performed, with a view to the integrated environmental management of this watershed. Out of the total area of the Schmidt stream watershed (23.92 km(2)), in terms of geology, it was observed that 23.7% consist of colluvial deposits, 22.6% consist of grass facies, and 53.7% consist of Botucatu formation. Major soil types of the watershed: 97.4% Argisols and only 2.6% Planosols. Land use and occupation is characterized by wetland (0.5%), Native Forest (12

  14. Integrated use of soil physical and water isotope methods for ecohydrological characterization of desertified areas

    NASA Astrophysics Data System (ADS)

    Külls, Christoph; Nunes, Alice; Köbel-Batista, Melanie; Branquinho, Cristina; Bianconi, Nadja; Costantini, Eduardo

    2014-05-01

    Measures for monitoring desertification and soil degradation require a thorough understanding of soil physical properties and of the water balance in order to guide restoration efforts (Costantini et al. 2009). It is hypothesized that long term restoration success on degraded land depends on a series of interacting factors such as exposition, soil type, soil hydrology including lateral flow on hill-slope catenae. Recently, new soil water isotope measurement techniques have been developed (Garvelmann et al. 2012) that provide much faster and reliable stable water isotope profiles in soils. This technique yield information on groundwater recharge, soil water balance and on the origin of water available for plants, which in combination with conservative chemical tracers (chloride) can be validated. A multidisciplinary study including ecologists, soil physicists and hydrologists of the COST Action Desert Restoration Hub was carried out on four semi-arid sites in Portugal. A comparative characterization of soil physical parameters, soil water isotope and chloride profiles was performed in order to estimate pedoclimate, soil aridity, soil water balance and groundwater recharge. In combination with soil physical data a comprehensive and cross-validated characterization of pedoclimate and soil aridity was obtained. These indicators were then integrated and related to plant cover. The long-term rainfall of the four sites ranges from 512 to 638 mm, whereas air temperature is from 15.8 to 17.0°C. The De Martonne index of aridity spans from 19.3 to 24.6, pointing to semiarid to moderately arid climatic conditions. The long-term average number of days when the first 0.50 m of soil is dry ranges from 110 to 134, while the mean annual soil temperature at 0.50 m spans from 15.8 and 19.1°C. The studied profiles show different hydrological characteristics, in particular, the estimated hydraulic conductivity ranges from 0.1-1 to 10-100 µm/s. Three out of four profiles show a

  15. Galvanneal Thermometry with a Thermographic Phosphor System

    SciTech Connect

    Manges, W.W., Allison, S.W. , Vehec, J.R.

    1997-12-31

    The accurate determination of temperature of galvanneal sheet emerging from a zinc bath is a challenging process measurement. The line moves at high speeds, up to 900 feet per minute, and the emissivity varies widely as it moves through the radio-frequency (RF) induction heating ovens and subsequently cools. This presents a great source of error if the pyrometric approach is used since the accuracy is sensitive to emissivity variation. This problem has been circumvented by an approach described here which uses a thermally sensitive phosphor technique for temperature measurement. For this, a small amount of a phosphor material is deposited on the liquid surface of the sheet. When the small layer of phosphor moves to the measurement station, it is illuminated by a short laser pulse which produces fluorescence from the material. The time dependence of the fluorescence indicates the temperature. Introduction of the microgram quantities of material has been shown to have no detrimental impact on product quality! This presentation describes a phosphor-based system for measuring temperature on a galvanneal manufacturing line. To date, measurements with an accuracy of +/- 5 deg F have been made at National Steel=s Midwest facility. This effort is a part of the Advanced Process Controls Program. The overall goal of the project is to provide accurate on-line temperature information that can be used to increase the yield and quality of the product, thereby reducing energy consumption and time.

  16. Dynamic high-temperature-phosphor thermometry

    SciTech Connect

    Tobin, K.W.; Capps, G.J.; Muhs, J.D.; Smith, D.B.; Cates, M.R.

    1990-08-01

    Dynamic surface phosphor thermometry is being investigated as part of a continuing effort by the Applied Technology Division (ATD) at Oak Ridge National Laboratory (ORNL) to develop and apply thermographic phosphor technology to an ever expanding thermometry field. The purpose of this program is to develop dynamic surface phosphor thermometry to a stage where funding proposals can be strengthened by establishing a strong information base and demonstrating a sound capability. As a new technology development in an area well established by ATD/ORNL, dynamic thermometry is extremely important for high-temperature materials, superconducting materials, advanced turbomachinery, space vehicles, industrial process equipment, and other development areas. This laboratory project illustrated the technique of continuously monitoring dynamic temperature excursions using phosphor thermography. Temperature-increase rates on the order of 100 or more degrees centigrade per millisecond were measured, which illustrated a temporal response of >0.001 s. This exceeded by a factor of ten the goal or the project and gave strong encouragement for further development of the technology. Important to the project, too, was the establishment of a clear analytical base for fluorescent-ratio data. Using the results of this study, specific solutions to dynamic-temperature-measurement problems in many application areas can be developed. In addition, the dynamic-thermographic technology can be coupled with strain measurement, two-dimensional analysis, and thermometry at very high temperatures to add interrelating remote measurement tools for systems that currently cannot be effectively studied. 13 refs., 11 figs.

  17. Corrosion free phosphoric acid fuel cell

    DOEpatents

    Wright, Maynard K.

    1990-01-01

    A phosphoric acid fuel cell with an electrolyte fuel system which supplies electrolyte via a wick disposed adjacent a cathode to an absorbent matrix which transports the electrolyte to portions of the cathode and an anode which overlaps the cathode on all sides to prevent corrosion within the cell.

  18. A high sensitive phosphor for dosimetric applications

    SciTech Connect

    Kore, Bhushan P. Dhoble, S. J.; Dhoble, N. S.; Lochab, S. P.

    2015-06-24

    In this study a novel TL phosphor CaMg{sub 3}(SO{sub 4}){sub 4}:Dy{sup 3+} was prepared by acid distillation method. The TL response of this phosphor towards γ-rays and carbon ion beam was tested. Good dosimetric glow curve was observed which is stable against both the type of radiations. The CaMg{sub 3}(SO{sub 4}){sub 4}:Dy{sup 3+} phosphor doped with 0.2 mol% of Dy{sup 3+}, irradiated with γ-ray shows nearly equal sensitivity to that of commercially available CaSO{sub 4}:Dy TLD phosphor whereas 3.5 times more sensitivity than CaSO{sub 4}:Dy, when irradiated with carbon ion beam. The change in glow peak intensities and glow peak temperature with variation in irradiation species and energy of ion beam is discussed here. The effect of these on trapping parameters is also illustrated.

  19. Homogeneous assay technology based on upconverting phosphors.

    PubMed

    Kuningas, Katri; Rantanen, Terhi; Ukonaho, Telle; Lövgren, Timo; Soukka, Tero

    2005-11-15

    Upconversion photoluminescence can eliminate problems associated with autofluorescence and scattered excitation light in homogeneous luminescence-based assays without need for temporal resolution. We have demonstrated a luminescence resonance energy-transfer-based assay utilizing inorganic upconverting (UPC) lanthanide phosphor as a donor and fluorescent protein as an acceptor. UPC phosphors are excited at near-infrared and they have narrow-banded anti-Stokes emission at visible wavelengths enabling measurement of the proximity-dependent sensitized emission with minimal background. The acceptor alone does not generate any direct emission at shorter wavelengths under near-infrared excitation. A competitive model assay for biotin was constructed using streptavidin-conjugated Er3+,Yb3+-doped UPC phosphor as a donor and biotinylated phycobiliprotein as an acceptor. UPC phosphor was excited at near-infrared (980 nm) and sensitized acceptor emission was measured at red wavelength (600 nm) by using a microtitration plate fluorometer equipped with an infrared laser diode and suitable excitation and emission filters. Lower limit of detection was in the subnanomolar concentration range. Compared to time-resolved fluorometry, the developed assay technology enabled simplified instrumentation. Excitation at near-infrared and emission at red wavelengths render the technology also suitable to analysis of strongly colored and fluorescent samples, which are often of concern in clinical immunoassays and in high-throughput screening. PMID:16285685

  20. Fundamental study of phosphor separation by controlling magnetic force

    NASA Astrophysics Data System (ADS)

    Wada, Kohei; Mishima, Fumihito; Akiyama, Yoko; Nishijima, Shigehiro

    2013-11-01

    The phosphor wastes consist of phosphors with different emission colors, green (LAP), red (YOX), blue (BAM) and white (HP). It is required to recover and reuse the rare earth phosphors with high market value. In this study, we tried to separate the phosphor using the magnetic separation by HTS bulk magnet utilizing the differences of magnetic susceptibility by the type of phosphors. We succeeded in the successive separation of HP with low market value from YOX and BAM including the rare earth using the magnetic Archimedes method. In this method, vertical and radial components of the magnetic force were used.

  1. Luminescence properties of phosphate phosphor Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+}

    SciTech Connect

    Yang, Fu; Liu, Yufeng; Tian, Xiaodong; Dong, Guoyi; Yu, Quanmao

    2015-05-15

    A series of reddish orange-emitting phosphate phosphors Ba{sub 3}Y{sub 1−x}(PO{sub 4}){sub 3}:xSm{sup 3+}(0.01≤x≤0.20) were synthesized by solid-state reaction. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of as-synthesized phosphors. The optimized phosphors Ba{sub 3}Y{sub 0.95}(PO{sub 4}){sub 3}:0.05Sm{sup 3+} present several excitation bands from 300 to 500 nm, and exhibit intense reddish orange-emitting properties. The energy transfer type between Sm{sup 3+} ions was confirmed as d–d interaction by using Van Uitert model. The chromatic properties of the typical sample Ba{sub 3}Y(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphor have been found to have chromaticity coordinates of (0.583, 0.405), which are located in reddish orange region under the excitation of 401 nm. These results indicated that Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors have potential applications in the field of lighting and display due to their effective excitation in the near-ultraviolet range. - Graphical abstract: The color coordinates for 5 mol% Sm{sup 3+} doped Ba{sub 3}Y(PO{sub 4}){sub 3} phosphor were calculated to be (0.583, 0.405), which are located in reddish orange region under the excitation of 401 nm. The peaks of Ba{sub 3}Y{sub 0.95}(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphor with the highest emission intensity at 600 nm are broader than those of Y{sub 2}O{sub 3}:Eu{sup 3+} and Y{sub 2}O{sub 2}S:Eu{sup 3+} phosphors. All these characteristics suggest that Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors are suitable for near-UV (370–410 nm) excitation and can be applicable to near UV-based WLEDs. ▪ - Highlights: • Different concentration Sm{sup 3+}-doped Ba{sub 3}Y(PO{sub 4}){sub 3} phosphors were fabricated by solid state method. • The optimized phosphors present the several excitation bands from 300 to 500 nm. • The Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} shows bright reddish orange

  2. Intravascular imaging with a storage phosphor detector

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.; Petrek, Peter; Matthews, Kenneth L., II; Fritz, Shannon G.; Bujenovic, L. Steven; Xu, Tong

    2010-05-01

    The aim of this study is to develop and test an intravascular positron imaging system based on a storage phosphor detector for imaging and detecting vulnerable plaques of human coronary arteries. The radiotracer F18-FDG accumulates in vulnerable plaques with inflammation of the overlying cap. The vulnerable plaques can, therefore, be imaged by recording positrons emitted from F18-FDG with a detector inserted into the artery. A prototype intravascular detector was constructed based on storage phosphor. The detector uses a flexible storage phosphor tube with 55 mm length, 2 mm diameter and 0.28 mm wall thickness. The intravascular detector is guided into the vessel using x-ray fluoroscopy and the accumulated x-ray signal must be erased prior to positron imaging. For this purpose, a light diffuser, 0.9 mm in diameter and 55 mm in length, was inserted into the detector tube. The light diffuser was connected to a laser source through a 2 m long optical fiber. The diffuser redirected the 0.38 W laser light to the inner surface of the phosphor detector to erase it. A heart phantom with 300 cm3 volume and three coronary arteries with 3.2 mm diameter and with several plaques was constructed. FDG solution with 0.5 µCi cm-3 activity concentration was filled in the heart and coronary arteries. The detector was inserted in a coronary artery and the signal from the plaques and surrounding background activity was recorded for 2 min. Then the phosphor detector was extracted and read out using a storage phosphor reader. The light diffuser erased the signal resulting from fluoroscopic exposure to level below that encountered during positron imaging. Vulnerable plaques with area activities higher than 1.2 nCi mm-2 were visualized by the detector. This activity is a factor of 10-20 lower than that expected in human vulnerable plaques. The detector was able to image the internal surface of the coronary vessels with 50 mm length and 360° circumference. Spatial resolution was 0

  3. PHYSICAL CHARACTERIZATION OF VITREOUS STATE LABORATORY AY102/C106 AND AZ102 HIGH LEVEL WASTE MELTER FEED SIMULANTS (U)

    SciTech Connect

    Hansen, E

    2005-03-31

    The objective of this task is to characterize and report specified physical properties and pH of simulant high level waste (HLW) melter feeds (MF) processed through the scaled melters at Vitreous State Laboratories (VSL). The HLW MF simulants characterized are VSL AZ102 straight hydroxide melter feed, VSL AZ102 straight hydroxide rheology adjusted melter feed, VSL AY102/C106 straight hydroxide melter feed, VSL AY102/C106 straight hydroxide rheology adjusted melter feed, and Savannah River National Laboratory (SRNL) AY102/C106 precipitated hydroxide processed sludge blended with glass former chemicals at VSL to make melter feed. The physical properties and pH were characterized using the methods stated in the Waste Treatment Plant (WTP) characterization procedure (Ref. 7).

  4. Physical interpretation and development of ultrasonic nondestructive evaluation techniques applied to the quantitative characterization of textile composite materials

    NASA Technical Reports Server (NTRS)

    Miller, James G.

    1992-01-01

    The development and implementation of advanced ultrasonic nondestructive evaluation methods applied to the characterization of composite materials requires a better understanding of the physics underlying the interaction of ultrasound with the material. The purpose of this investigation is to identify and characterize the features of complex, three dimensional materials that limit the ability of ultrasound to detect flaws in this broad class of emerging materials. In order to explore the interaction of ultrasound with such complex media, we investigate the characteristics of ultrasonic fields which have propagated through samples with complex geometries and/or internal architecture. We focus on the physics that underlies the detection of flaws in such materials.

  5. Synthesis and luminescence properties of red-emitting M2Si5N8:Eu2+-based (M=Ca, Sr, Ba) phosphors by a simple nitrate reduction

    NASA Astrophysics Data System (ADS)

    Chen, ChangCheng; Xie, ErQing

    2014-03-01

    M2Si5N8:Eu2+-based (M=Ca, Sr, Ba) red-emitting phosphors are fabricated at relatively low temperature (1200°C) and atmospheric pressure using a simple solid-state reaction process. Several processing parameters are systematically investigated to optimize the phosphors structural characterization and photoluminescence performance, including the amount of europium and the properties of the precursor materials. The as-prepared M2Si5N8:Eu2+-based (M=Ca, Sr, Ba) phosphors are orange in color and are intensively emitted in the red region of 580-670 nm under 465 nm excitation.

  6. Decontamination Efficiency of a DBD Lamp Containing an UV-C Emitting Phosphor.

    PubMed

    Caillier, Bruno; Caiut, José Maurício Almeida; Muja, Cristina; Demoucron, Julien; Mauricot, Robert; Dexpert-Ghys, Jeanette; Guillot, Philippe

    2015-01-01

    Among different physical and chemical agents, the UV radiation appears to be an important route for inactivation of resistant microorganisms. The present study introduces a new mercury-free Dielectric Barrier Discharge (DBD) flat lamp, where the biocide action comes from the UV emission produced by rare-earth phosphor obtained by spray pyrolysis, following plasma excitation. In this study, the emission intensity of the prototype lamp is tuned by controlling gas pressure and electrical power, 500 mbar and 15 W, corresponding to optimal conditions. In order to characterize the prototype lamp, the energetic output, temperature increase following lamp ignition and ozone production of the source were measured. The bactericidal experiments carried out showed excellent results for several gram-positive and gram-negative bacterial strains, thus demonstrating the high decontamination efficiency of the DBD flat lamp. Finally, the study of the external morphology of the microorganisms after the exposure to the UV emission suggested that other mechanisms than the bacterial DNA damage could be involved in the inactivation process. PMID:25626463

  7. Multi-Attribute Seismic/Rock Physics Approach to Characterizing Fractured Reservoirs

    SciTech Connect

    Gary Mavko

    2004-11-30

    Most current seismic methods to seismically characterize fractures in tight reservoirs depend on a few anisotropic wave propagation signatures that can arise from aligned fractures. While seismic anisotropy can be a powerful fracture diagnostic, a number of situations can lessen its usefulness or introduce interpretation ambiguities. Fortunately, laboratory and theoretical work in rock physics indicates that a much broader spectrum of fracture seismic signatures can occur, including a decrease in P- and S-wave velocities, a change in Poisson's ratio, an increase in velocity dispersion and wave attenuation, as well as well as indirect images of structural features that can control fracture occurrence. The goal of this project was to demonstrate a practical interpretation and integration strategy for detecting and characterizing natural fractures in rocks. The approach was to exploit as many sources of information as possible, and to use the principles of rock physics as the link among seismic, geologic, and log data. Since no single seismic attribute is a reliable fracture indicator in all situations, the focus was to develop a quantitative scheme for integrating the diverse sources of information. The integrated study incorporated three key elements: The first element was establishing prior constraints on fracture occurrence, based on laboratory data, previous field observations, and geologic patterns of fracturing. The geologic aspects include analysis of the stratigraphic, structural, and tectonic environments of the field sites. Field observations and geomechanical analysis indicates that fractures tend to occur in the more brittle facies, for example, in tight sands and carbonates. In contrast, strain in shale is more likely to be accommodated by ductile flow. Hence, prior knowledge of bed thickness and facies architecture, calibrated to outcrops, are powerful constraints on the interpreted fracture distribution. Another important constraint is that fracturing

  8. Physics of ultrasonic wave propagation in bone and heart characterized using Bayesian parameter estimation

    NASA Astrophysics Data System (ADS)

    Anderson, Christian Carl

    This Dissertation explores the physics underlying the propagation of ultrasonic waves in bone and in heart tissue through the use of Bayesian probability theory. Quantitative ultrasound is a noninvasive modality used for clinical detection, characterization, and evaluation of bone quality and cardiovascular disease. Approaches that extend the state of knowledge of the physics underpinning the interaction of ultrasound with inherently inhomogeneous and isotropic tissue have the potential to enhance its clinical utility. Simulations of fast and slow compressional wave propagation in cancellous bone were carried out to demonstrate the plausibility of a proposed explanation for the widely reported anomalous negative dispersion in cancellous bone. The results showed that negative dispersion could arise from analysis that proceeded under the assumption that the data consist of only a single ultrasonic wave, when in fact two overlapping and interfering waves are present. The confounding effect of overlapping fast and slow waves was addressed by applying Bayesian parameter estimation to simulated data, to experimental data acquired on bone-mimicking phantoms, and to data acquired in vitro on cancellous bone. The Bayesian approach successfully estimated the properties of the individual fast and slow waves even when they strongly overlapped in the acquired data. The Bayesian parameter estimation technique was further applied to an investigation of the anisotropy of ultrasonic properties in cancellous bone. The degree to which fast and slow waves overlap is partially determined by the angle of insonation of ultrasound relative to the predominant direction of trabecular orientation. In the past, studies of anisotropy have been limited by interference between fast and slow waves over a portion of the range of insonation angles. Bayesian analysis estimated attenuation, velocity, and amplitude parameters over the entire range of insonation angles, allowing a more complete

  9. Ink jet inks and substrates: Novel approaches for their physical and optical properties characterization

    NASA Astrophysics Data System (ADS)

    Lovell, Veronika

    Undoubtedly, within the last couple of decades, the progress in non impact printing technologies has grown to an enormous level. In order to keep the development of this non impact printing method to grow even more, technicians, researchers and educators must continue in conducting investigation and provoking new ideas and questions that will lead to new outcomes and expansion of ink jet printing. In this work, a broader area that comprises deep look into the ink jet ink and substrate performance, their physical properties and optical properties when printed is discussed in great details. Innovative techniques, novel materials and novel recommendations are presented here in order to enhance the progress in the area of ink jet technology in near future. The output should be evaluated in terms of overall printer capability, not only in terms of a substrate quality (price, grade, optical and physical properties), the type of ink set, and the basic level of color reproduction (density, Lab values). All these should be taken into consideration together with other very important factors, such as the length of time required for colors to stabilize, the image permanence of the printout, and the ink levels in terms of color gamut. The work includes a comprehensive study of ink and substrate combinations, the interaction between them, and integration of novel techniques, two and three dimensional color gamut projections and gamut volume values, into color output characterization. Using this method it is possible to demonstrate how properties of a substrate correlate with the final output presentation. The aforementioned approach can be also used as an image permanence evaluation technique, in preference to the change in densities and L*a*b* values of miniature charts. Definitely, the gamut volume can be utilized as a sophisticated device, which enables to control the final color output of the printing job.

  10. Characterization and Physical Mapping of Ribosomal RNA Gene Families in Plantago

    PubMed Central

    DHAR, MANOJ K.; FRIEBE, BERND; KAUL, SANJANA; GILL, BIKRAM S.

    2006-01-01

    • Background and Aims The organization of rRNA genes in cultivated Plantago ovata Forsk. and several of its wild allies was analysed to gain insight into the phylogenetic relationships of these species in the genus which includes some 200 species. • Methods Specific primers were designed to amplify the internal transcribed spacer (ITS1 and ITS2) regions from seven Plantago species and the resulting fragments were cloned and sequenced. Similarly, using specific primers, the 5S rRNA genes from these species were amplified and subsequently cloned. Fluorescence in-situ hybridization (FISH) was used for physical mapping of 5S and 45S ribosomal RNA genes. • Results The ITS1 region is 19–29 bp longer than the ITS2 in different Plantago species. The 5S rRNA gene-repeating unit varies in length from 289 to 581 bp. Coding regions are highly conserved across species, but the non-transcribed spacers (NTS) do not match any database sequences. The clone from the cultivated species P. ovata was used for physical mapping of these genes by FISH. Four species have one FISH site while three have two FISH sites. In P. lanceolata and P. rhodosperma, the 5S and 45S (18S-5·8S-25S) sites are coupled. • Conclusions Characterization of 5S and 45S rRNA genes has indicated a possible origin of P. ovata, the only cultivated species of the genus and also the only species with x = 4, from a species belonging to subgenus Psyllium. Based on the studies reported here, P. ovata is closest to P. arenaria, although on the basis of other data the two species have been placed in different subgenera. FISH mapping can be used as an efficient tool to help determine phylogenetic relationships in the genus Plantago and show the interrelationship between P. lanceolata and P. lagopus. PMID:16481363

  11. Hydrodynamics Flow and Transport Characterization of a Karstified Physical Model Using Temporal Moment Analysis

    NASA Astrophysics Data System (ADS)

    Anaya, A. A.; Padilla, I. Y.

    2013-12-01

    High productivity of karst groundwater systems is often associated with conduit flow and high matrix permeability. Spatial heterogeneities and anisotropy, among others factors, result in highly complex flow patterns in these systems. The same characteristics that make these aquifers very productive also make them highly vulnerable to contamination and a likely for contaminant exposure. The understanding of contamination fate and transport processes in these complex aquifers demand different statistical and numerical approaches, such as the Temporal Moment Analysis (TMA). TMA of solute breakthrough curves provide qualitative and quantitative results to characterize hydrodynamic variables that affect the release, mobility, persistence, and possible pathways of contaminants in karst groundwater systems. The general objective of this work is to characterize flow and transport processes in conduit and diffusion-dominated flow under low and high flow conditions using TMA in a karstified physical model. A multidimensional, laboratory-scale, Geo-Hydrobed model (GHM) containing a karstified limestone block collected from the karst aquifer formation of northern Puerto Rico are used for this purpose. Experimental work entails injecting dissolved CaCl2 and trichloroethene (TCE) in the upstream boundary of the GHM while monitoring their concentrations spatially and temporally in the limestone under different groundwater flow regimes. Results from the TMA show a highly heterogeneous system resulting in large preferential flow components and specific mass-transfer limitations zones especially in diffuse flow areas. Flow variables like velocity and Reynolds number indicates defined preferential flow paths increasing spatially as flow rate increase. TMA results show to be qualitatively consistent with a previous statistical novel approach developed using mixed models. Comparison between the dissolved CaCl2 tracer and TCE show implications for reactive contaminants in the karst

  12. Contact lens physical properties and lipid deposition in a novel characterized artificial tear solution

    PubMed Central

    Heynen, Miriam; Kay, Lise M.M.; Dominici, Claudia Yvette; Khan, Warda; Ng, Wendy W.S.; Jones, Lyndon

    2011-01-01

    Purpose To characterize various properties of a physiologically-relevant artificial tear solution (ATS) containing a range of tear film components within a complex salt solution, and to measure contact lens parameters and lipid deposition of a variety of contact lens materials after incubation in this ATS. Methods A complex ATS was developed that contains a range of salts, proteins, lipids, mucin, and other tear film constituents in tear-film relevant concentrations. This ATS was tested to confirm that its pH, osmolality, surface tension, and homogeneity are similar to human tears and remain so throughout the material incubation process, for up to 4 weeks. To confirm that silicone hydrogel and conventional hydrogel contact lens materials do not alter in physical characteristics beyond what is allowed by the International Organization for Standardization (ISO) 18369–2. The diameter, center thickness, and calculated base curve were measured for five different lens materials directly out of the blister pack, after a rinse in saline and then following a two week incubation in the modified ATS. To test the ATS and the effect of its composition on lipid deposition, two lens materials were incubated in the ATS and a modified version for several time points. Both ATS solutions contained trace amounts of carbon-14 cholesterol and phosphatidylcholine, such that deposition of these specific lipids could be quantified using standard methods. Results This ATS is a complex mixture that remains stable at physiologically relevant pH (7.3–7.6), osmolality (304–306 mmol/kg), surface tension (40–46 dynes/cm) and homogeneity over an incubation period of three weeks or more. The physical parameters of the lenses tested showed no changes beyond that allowed by the ISO guidelines. Incubations with the ATS found that balafilcon A lenses deposit significantly more cholesterol and phosphatidylcholine than omafilcon A lenses (p<0.05) and that removing lactoferrin and immunoglobulin G

  13. A Visual Detection System for Determining Tritium Surface Deposition Employing Phosphor Coated Materials

    SciTech Connect

    C.A. Gentile; C.H. Skinner; K.M. Young; S.J. Zweben; et al

    1999-10-01

    A method for visually observing tritium deposition on the surface of the Tokamak Fusion Test Reactor (TFTR) deuterium-tritium (D-T) tiles is being investigated at the Princeton Plasma Physics Laboratory. A green phosphor (P31, zinc sulfide: copper) similar to that used in oscilloscope screens with a wavelength peak of 530 nm was positioned on the surface of a TFTR D-T tile. The approximately 600 gram tile, which contains approximately 1.5 Ci of tritium located on the top approximately 1-50 microns of the surface, was placed in a two liter lexan chamber at Standard Temperature and Pressure (STP). The phosphor plates and phosphor powder were placed on the surface of the tile which resulted in visible light being observed, the consequence of tritium betas interacting with the phosphor. This technique provides a method of visually observing varying concentrations of tritium on the surface of D-T carbon tiles, and may be employed (in a calibrated system) to obtain quantitative data.

  14. Corrosion-resistant catalyst supports for phosphoric acid fuel cells

    SciTech Connect

    Kosek, J.A.; Cropley, C.C.; LaConti, A.B.

    1990-01-01

    High-surface-area carbon blacks such as Vulcan XC-72 (Cabot Corp.) and graphitized carbon blacks such as 2700{degree}C heat-treated Black Pearls 2000 (HTBP) (Cabot Corp.) have found widespread applications as catalyst supports in phosphoric acid fuel cells (PAFCs). However, due to the operating temperatures and pressures being utilized in PAFCs currently under development, the carbon-based cathode catalyst supports suffer from corrosion, which decreases the performance and life span of a PAFC stack. The feasibility of using alternative, low-cost, corrosion-resistant catalyst support (CRCS) materials as replacements for the cathode carbon support materials was investigated. The objectives of the program were to prepare high-surface-area alternative supports and to evaluate the physical characteristics and the electrochemical stability of these materials. The O{sub 2} reduction activity of the platinized CRCS materials was also evaluated. 2 refs., 3 figs.

  15. Physical characterization of explosive volcanic eruptions based on tephra deposits: Propagation of uncertainties and sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Bonadonna, Costanza; Biass, Sébastien; Costa, Antonio

    2015-04-01

    Regardless of the recent advances in geophysical monitoring and real-time quantitative observations of explosive volcanic eruptions, the characterization of tephra deposits remains one of the largest sources of information on Eruption Source Parameters (ESPs) (i.e. plume height, erupted volume/mass, Mass Eruption Rate - MER, eruption duration, Total Grain-Size Distribution - TGSD). ESPs are crucial for the characterization of volcanic systems and for the compilation of comprehensive hazard scenarios but are naturally associated with various degrees of uncertainties that are traditionally not well quantified. Recent studies have highlighted the uncertainties associated with the estimation of ESPs mostly related to: i) the intrinsic variability of the natural system, ii) the observational error and iii) the strategies used to determine physical parameters. Here we review recent studies focused on the characterization of these uncertainties and we present a sensitivity analysis for the determination of ESPs and a systematic investigation to quantify the propagation of uncertainty applied to two case studies. In particular, we highlight the dependence of ESPs on specific observations used as input parameters (i.e. diameter of the largest clasts, thickness measurements, area of isopach contours, deposit density, downwind and crosswind range of isopleth maps, and empirical constants and wind speed for the determination of MER). The highest uncertainty is associated to the estimation of MER and eruption duration and is related to the determination of crosswind range of isopleth maps and the empirical constants used in the empirical parameterization relating MER and plume height. Given the exponential nature of the relation between MER and plume height, the propagation of uncertainty is not symmetrical, and both an underestimation of the empirical constant and an overestimation of plume height have the highest impact on the final outcome. A ± 20% uncertainty on thickness

  16. Preparation and Photoluminescence of Sm (3+) Doped YAlO 3 Phosphor.

    PubMed

    Baig, Huma Nazli; Saluja, Jagjeet Kaur; Harnath, D; Prasad, A S Sai; Murthy, K V R

    2016-05-01

    YAlO3: Sm(3+) phosphor has been synthesized by the solid state reaction method with calcium flouride used as a flux. The resulting YAlO3: Sm(3+) phosphor was characterized by X-ray diffraction (XRD) technique, Fourier transmission infrared spectroscopy (FTIR), photoluminescence . . PL excitation spectrum was found at 254,332,380,400,407, 603 and 713 nm. Under excitation of UV(713 nm) YAlO3: Sm(3+) (0-3 %) broad band emission were observed from 400 to 790 nm with a maximum around 713 nm of YAlO3 host lattice accompanied by weak emission of Sm(3+) ((4)G5/2 - (6)H5/2, (6)H7/2,(6)H9/2) transitions. The results of the XRD show that obtained YAlO3: Sm(3+) phosphor has a orthorhombic structure. The study suggested that Sm(3+) doped phosphors are potential luminescence material for laser diode pumping and inorganic scintillators. PMID:26983716

  17. Thermoluminescence in β-irradiated SrZnF4:Dy TLD phosphor

    NASA Astrophysics Data System (ADS)

    Shelke, Tushar R.; Dhoble, S. J.; Nanoti, V. M.

    2014-02-01

    SrZnF4:Dy phosphor was prepared by the wet chemical synthesis and characterized for its X-ray diffraction, thermoluminescence (TL) and photoluminescence (PL) properties. The PL emission spectra for SrZnF4:Dy3+ phosphor at 351 nm excitation give emission at 481 nm (blue) and 575 nm (yellow). The TL properties of SrZnF4:Dy were studied using β-irradiation. The response curve of the prepared phosphor with high-dose β-ray exposure is linear as compared with well-known CaSO4:Dy phosphor. The TL glow curves of SrZnF4:Dy sample showed two well-defined peaks at 143°C (peak-1) and 231°C (peak-2) indicating that two sets of traps are being activated within the particular temperature range and the trapping parameter associated with the prominent glow peaks of SrZnF4:Dy is calculated by using Chen's method.

  18. Synthesis and study on the luminescence properties of cadmium borate phosphors

    SciTech Connect

    Annalakshmi, O.; Jose, M.T.; Venkatraman, B.; Amarendra, G.

    2014-02-01

    Highlights: • Cadmium borate synthesized by solid state sintering technique. • Neutron sensitivity of the material ten times that of TLD-600. • Gamma sensitivity is found to be twice that of TLD-100. • Gamma response is linear from 0.1 to 10{sup 3} mGy. - Abstract: Cadmium borate compound prepared through wet chemical reaction from the starting chemicals followed by high temperature solid state synthesis below the melting point to get the final TL phosphor powder. Phase purity and bond details of cadmium borate crystals are characterized using X-ray diffraction technique and infrared spectroscopy. Feasibility of these materials for radiation dosimetry applications was studied after gamma and neutron irradiation. Gamma irradiation of undoped phosphors show a single peak around 185 °C whereas doping with gadolinium and silver, new more intense peak observed at 290 °C. Irradiation to thermal neutrons revealed single peak around 170 °C for all the phosphors. TL emission spectra and photoluminescence (PL) studies were also carried out on the phosphors. These borate materials are found to be highly sensitive to neutrons and hence can be used for neutron detection. Neutron sensitivity of the material is about ten times that of TLD-600.

  19. Near-infrared Downconversion in LuPO4: Tm3+, Yb3+ Phosphors.

    PubMed

    Li, Li; Wang, Yongjie; Shen, Jun; Chang, Wenxuan; Jin, Tianting; Wei, Xiantao; Tian, Ya

    2016-04-01

    Tm3+ and Yb3+ codoped LuPO4 phosphors were synthesized by the reverse-strike co-precipitation method. The obtained LuPO4:Tm3+,Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra, and decay lifetime to understand the observed near-infrared downconversion (DC) phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of LuPO4 and exhibit good crystallinity. The experimental results showed that the strong visible emission around 649 nm from Tm3+(1G4 --> 3F4) and near-infrared (NIR) emission around 1003 nm from Yb3+(2F5/2 --> 2F7/2) of LuPO4:Tm3+,Yb3+ phosphors were observed under 468 nm excitation, respectively. The Yb3+ concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches 30 mol%. The DC mechanism is also discussed in detail. PMID:27451658

  20. Mechanical and thermo-physical characterization of the carbon fibre composite NB31

    NASA Astrophysics Data System (ADS)

    Pintsuk, G.; Compan, J.; Linke, J.; Majerus, P.; Peacock, A.; Pitzer, D.; Rödig, M.

    2007-03-01

    The use of carbon-based materials, i.e. graphite and carbon fibre composites (CFCs), as plasma facing materials in experimental nuclear fusion devices is widely spread. For the strike point area of the ITER divertor, a European candidate material was NB31, a three directional (3D) CFC material consisting of ex-pitch, ex-PAN and needled ex-PAN fibres, which will be replaced in the future by the newly developed material NB41. This composite material is used for the fabrication of divertor components for Wendelstein 7-X. In the frame of an extensive characterization on three different material batches of NB31 called 'pilot', 'serial' and 'additional' productions for W7-X and ITER, thermo-physical measurements and tensile tests were performed. The results were correlated to density and microstructure. The latter varied due to difficulties in the manufacturing process, in particular in the needling process. Therefore the specification of a minimum density and unit cell width (combined thickness of an ex-pitch and ex-PAN layer) is necessary to meet the ITER specifications for tensile strength and for thermal conductivity in the ex-pitch direction.

  1. Morphological investigation and physical characterization of ancient fragments of pyrogenic carbon

    NASA Astrophysics Data System (ADS)

    Pusceddu, E.; Criscuoli, I.; Miglietta, F.

    2013-12-01

    In the latest years, the attention toward the use of pyrogenic carbon as a climate mitigation strategy has increasingly grown. Biochar (BC) contains substantial amount (60-90%) of pyrogenic carbon, which is a recalcitrant material and it is hardly decomposed by biotic and abiotic oxidation. The carbon mitigation potential of biochar is associated to the fact that carbon is not easily released back into the atmosphere, even after very long incubation time in the soil. Several studies have been addressing the understanding of the fate of pyrogenic carbon in the soil in a quantitative way, but only a few actually considered materials that were produced in the past and they were not fully able to estimate the fraction of carbon that was oxidized on centennial time scales. In this paper, an old deposits of biochar in soils of the Eastern Alps (Trentino, Val di Pejo) was dated at 1859 by means of a dendroanthracological approach. Carbon decomposition in those soils was then investigated to calculate the fraction of carbon that was lost over 155 years. Part of this study is focused on the morphological and physical characterization of several fragments of biochar, using a scanning electron microscope (SEM). Such study enabled the identification of specific morphological features of tracheids in the old biochar, which were tentatively associated to a differential oxidation of the structures that were created during carbonization from lignin and cellulose.

  2. Chemical, physical, structural and morphological characterization of the electric arc furnace dust.

    PubMed

    Machado, Janaína G M S; Brehm, Feliciane Andrade; Moraes, Carlos Alberto Mendes; Santos, Carlos Alberto Dos; Vilela, Antônio Cezar Faria; Cunha, João Batista Marimon da

    2006-08-25

    Electric arc furnace dust (EAFD) is a hazardous industrial waste generated in the collection of particulate material during steelmaking process via electric arc furnace. Important elements to the industry such as, Fe and Zn are the main ones in EAFD. Due to their presence, it becomes very important to know how these elements are combined before studying new technologies for its processing. The aim of this work was to carry out a chemical, physical, structural and morphological characterization of the EAFD. The investigation was carried out by using granulometry analysis, chemical analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy via SEM (EDS), X-ray mapping analysis via SEM, X-ray diffraction (XRD) and Mössbauer spectroscopy. By XRD the following phases were detected: ZnFe(2)O(4), Fe(3)O(4), MgFe(2)O(4), FeCr(2)O (4), Ca(0.15)Fe(2.85)O(4), MgO, Mn(3)O(4), SiO(2) and ZnO. On the other hand, the phases detected by Mössbauer spectroscopy were: ZnFe(2)O(4), Fe(3)O(4), Ca(0.15)Fe(2.85)O(4) and FeCr(2)O(4). Magnesium ferrite (MgFe(2)O(4)), observed in the XRD pattern as overlapped peaks, was not identified in the Mössbauer spectroscopy analysis. PMID:16494997

  3. Physical-chemical characterization of Tunisian clays for the synthesis of geopolymers materials

    NASA Astrophysics Data System (ADS)

    Selmani, S.; Essaidi, N.; Gouny, F.; Bouaziz, S.; Joussein, E.; Driss, A.; Sdiri, A.; Rossignol, S.

    2015-03-01

    Natural clay materials from Tunisia were examined as an aluminosilicate source for the synthesis of consolidated materials at low temperatures. Three clay samples were collected from the El Kef, Douiret and Gafsa basins and calcined at different temperatures. All of the samples were characterized using chemical and mineralogical analyses, thermogravimetry, dilatometry, and Fourier transform infrared spectroscopy (FTIR) measurements. The chemical (XRF) and mineralogical analyses (XRD and FTIR) indicated that all of the samples contained various amounts of kaolinite and quartz, followed by calcite, mica, palygorskite and gypsum. Curing produced a binder which did not significantly affect the physic-chemical properties of these clays. The obtained materials heterogeneous did not reach the geopolymerization stage, most likely because of their low kaolinite content. The addition of a suitable aluminosilicate to these clays is therefore recommended to produce homogeneous consolidated geopolymers. The synthesized materials obtained after the addition of metakaolin to the formulation to improve reactivity have interesting properties, thereby providing good potential for Tunisian clays in the synthesis of geopolymers.

  4. Fuel Thermo-physical Characterization Project: Evaluation of Models to Calculate Thermal Diffusivity of Layered Composites

    SciTech Connect

    Burkes, Douglas; Casella, Amanda J.; Gardner, Levi D.; Casella, Andrew M.; Huber, Tanja K.; Breitkreutz, Harald

    2015-02-11

    The Office of Material Management and Minimization Fuel Thermo-physical Characterization Project at Pacific Northwest National Laboratory (PNNL) is tasked with using PNNL facilities and processes to receive irradiated low enriched uranium-molybdenum fuel plate samples and perform analyses in support of the Office of Material Management and Minimization Reactor Conversion Program. This work is in support of the Fuel Development Pillar that is managed by Idaho National Laboratory. A key portion of the scope associated with this project was to measure the thermal properties of fuel segments harvested from plates that were irradiated in the Advanced Test Reactor. Thermal diffusivity of samples prepared from the fuel segments was measured using laser flash analysis. Two models, one developed by PNNL and the other developed by the Technische Universität München (TUM), were evaluated to extract the thermal diffusivity of the uranium-molybdenum alloy from measurements made on the irradiated, layered composites. The experimental data of the “TC” irradiated fuel segment was evaluated using both models considering a three-layer and five-layer system. Both models are in acceptable agreement with one another and indicate that the zirconium diffusion barrier has a minimal impact on the overall thermal diffusivity of the monolithic U-Mo fuel.

  5. Potato pulp: microbiological characterization, physical modification, and application of this agricultural waste product.

    PubMed

    Mayer, F; Hillebrandt, J O

    1997-10-01

    Potato pulp, one of the agricultural waste products obtained in high quantities during starch production, contains starch, cellulose, hemicelluloses, pectin, proteins, free amino acids and salts. It exhibits physical and physicochemical properties of a typical colloid. It is mainly used, in a dried and pelleted form, as cattle feed. Its autochthonic microbial flora (bacteria, fungi) was identified and studied with a view towards the degradative potential of the microorganisms and ways of conserving the pulp for subsequent technical applications; 33 isolates (28 bacteria, 4 fungi, 1 yeast), belonging to 15 genera were characterized. Biological conservation was possible at very low oxygen pressure, brought about by the autochthonic anaerobic microorganisms causing acidification. Chemical conservation was achieved with sorbic acid. By treatment with hot water vapour under pressure (autoclaving), followed by a pressure release procedure, intact cells in the pulp (both potato cells and microorganisms, not spores) were destroyed, and their contents and wall fragments were set free. This process resulted in low drying costs and was a prerequisite for the production of a powder that can be used as glue or as animal feed. PMID:9390450

  6. Estimation and characterization of physical and inorganic chemical indicators of water quality by using SAR images

    NASA Astrophysics Data System (ADS)

    Shareef, Muntadher A.; Toumi, Abdelmalek; Khenchaf, Ali

    2015-10-01

    Recently, remote sensing is considering one of the most important tools in studies of water scattering and water characterization. Traditional methods for monitoring pollutants depended on optical satellite rather than Radar data. Thus, many of Water Quality Parameters (WQP) from optical imagery are still limited. In this paper, a new approach based on the TerraSAR-X images has been presented which it is used to map the region of interest and to estimate physical and chemical WQPs. This approach based on a Small Perturbation Model (SPM) for the electromagnetic scattering is applied by using the Elfouhaily spectrum. A series of inversions have been included in this model started by finding the reflectivity from backscattering coefficients which are calculated from SAR images. Another inversion has been applied to find dielectric constant from the calculation models of the reflectivity (in HH and VV polarizations). Then, a Stogryn Debye formulation has been used to estimate temperature and salinity of water surface from SAR images. After many derivations we got a new model able to estimate temperature and salinity directly from backscattering coefficients obtained from radar images. Inorganic chemical parameters which are represented by Total Dissolved Salts (TDS) and the Electrical Conductivity (EC) are estimated directly from salinity. A tow dataset of instu data have been used to validate this work. The validation included a comparison between parameters measured in situ and those estimated from Terra SAR-X image.

  7. Physical and photophysical characterization of a BODIPY phosphatidylcholine as a membrane probe.

    PubMed Central

    Dahim, Mohammed; Mizuno, Nancy K; Li, Xin-Min; Momsen, William E; Momsen, Maureen M; Brockman, Howard L

    2002-01-01

    Lipids containing the dimethyl BODIPY fluorophore are used in cell biology because their fluorescence properties change with fluorophore concentration (C.-S. Chen, O. C. Martin, and R. E. Pagano. 1997. Biophys J. 72:37-50). The miscibility and steady-state fluorescence behavior of one such lipid, 1-palmitoyl-2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-sn-glycero-3-phosphocholine (PBPC), have been characterized in mixtures with 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC). PBPC packs similarly to phosphatidylcholines having a cis-unsaturated acyl chain and mixes nearly ideally with SOPC, apparently without fluorophore-fluorophore aggregation. Increasing PBPC mole fraction from 0.0 to 1.0 in SOPC membranes changes the emission characteristics of the probe in a continuous manner. Analysis of these changes shows that emission from the excited dimethyl BODIPY monomer self quenches with a critical radius of 25.9 A. Fluorophores sufficiently close (< or =13.7 A) at the time of excitation can form an excited dimer, emission from which depends strongly on total lipid packing density. Overall, the data show that PBPC is a reasonable physical substitute for other phosphatidylcholines in fluid membranes. Knowledge of PBPC fluorescence in lipid monolayers has been exploited to determine the two-dimensional concentration of SOPC in unilamellar, bilayer membranes. PMID:12202376

  8. Chemical and physical characterization of western low-rank-coal waste materials

    SciTech Connect

    Thompson, Carol May

    1981-03-01

    Evaluations of disposal requirements for solid wastes from power stations burning low-rank western coals is the primary objective of this program. Solid wastes to be characterized include: fly ashes, sludges from wet scrubbers, solids from fluidized bed combustion (FBC) processes and solids from dry scrubbing systems. Fly ashes and sludges to be studied will be obtained primarily from systems using alkaline fly ashes as significant sources of alkalinity for sulfur dioxide removal. Fluidized bed combustion wastes will include those produced by burning North Dakota lignite and Texas lignite. Dry scrubbing wastes will include those from spray drying systems and dry injection systems. Spray dryer wastes will be from a system using sodium carbonate as the scrubbing reagent. Dry injection wastes will come from systems using nahcolite and trona as sorbents. Spray dryer wastes, dry injection wastes, and FBC wastes will be supplied by the Grand Forks Energy Technology Center. Sludges and other samples will be collected at power stations using fly ash to supply alkalinity to wet scrubbers for sulfur dioxide removal. Sludges will be subjected to commercial fixation processes. Coal, fly ashes, treated and untreated sludges, scrubber liquor, FBC wastes, and dry scrubbing wastes will be subjected to a variety of chemical and physical tests. Results of these tests will be used to evaluate disposal requirements for wastes frm the systems studied.

  9. Physical and chemical characterization of petroleum products by GC-MS.

    PubMed

    Mendez, A; Meneghini, R; Lubkowitz, J

    2007-01-01

    There is a need for reliable and fast means of monitoring refining, conversion, and upgrading processes aiming to increase the yield of light distillates, and thus, reducing the oil barrel bottoms. By simultaneously utilizing the FID and mass selective detectors while splitting the column effluent in a controlled way, it is possible to obtain identical gas chromatograms and total ion chromatograms from a single run. This means that besides the intensity vs. time graphs, the intensity vs. mass and boiling point can also be obtained. As a result, physical and chemical characterization can be performed in a simple and rapid manner. Experimental results on middle, heavy distillates, and crude oil fractions show clearly the effect of upgrading processes on the chemical composition and yields of diesel, jet fuels, and high vacuum gasoil fractions. The methodology is fully compliant with ASTM D-2887, D-7213, D-6352, and D7169 for simulated distillation and the previously mentioned mass spectrometry standards. The group type analysis correlated satisfactorily with high-performance liquid chromatography data. PMID:18078577

  10. Preparation, physical-chemical and biological characterization of chitosan nanoparticles loaded with lysozyme.

    PubMed

    Piras, Anna Maria; Maisetta, Giuseppantonio; Sandreschi, Stefania; Esin, Semih; Gazzarri, Matteo; Batoni, Giovanna; Chiellini, Federica

    2014-06-01

    A commercially available chitosan (CS) was employed in the formulation of nanoparticles loaded with lysozyme (LZ) as antimicrobial protein drug model. Due to the variability of commercially available batches of chitosans and to the strict dependence of their physical and biological properties to the molecular weight (Mw) and deacetylation degree (DD) of the material, the CS was fully characterized resulting in weight-average molecular weight of 108,120g/mol and DD of 92%. LZ-loaded nanoparticles (LZ-NPs) of 150nm diameter were prepared by inotropic gelation. The nanoparticles were effectively preserving the antibacterial activity of the loaded enzyme, which was slowly released over 3 weeks in vitro and remained active toward Staphylococcus epidermidis up to 5 days of incubation. Beyond the intrinsic antibacterial activity of CS and LZ, the LZ-NPs evidenced a sustained antibacterial activity that resulted in about 2 log reduction of the number of viable S. epidermidis compared to plain CS nanoparticles. Furthermore, the LZ-NPs showed a full in vitro cytocompatibility toward murine fibroblasts and, in addition to the potential antimicrobial applications of the developed system, the proposed study could serve as an optimal model for development of CS nanoparticles carrying antimicrobial peptides for biomedical applications. PMID:24661890

  11. OGLE-2005-BLG-018: CHARACTERIZATION OF FULL PHYSICAL AND ORBITAL PARAMETERS OF A GRAVITATIONAL BINARY LENS

    SciTech Connect

    Shin, I.-G.; Han, C.; Udalski, A.; Kubiak, M.; Szymanski, M. K.; Pietrzynki, G.; Soszynski, I.; Ulaczyk, K.; Wyrzykowski, L.; Gould, A.; Gaudi, B. S.; Pogge, R. W.; Dominik, M.; Fouque, P.; DePoy, D. L.; Dong, S.; Lee, C.-U.; Park, B.-G.; Albrow, M. D.; Allan, A.

    2011-07-10

    We present the result of the analysis of the gravitational binary-lensing event OGLE-2005-BLG-018. The light curve of the event is characterized by two adjacent strong features and a single weak feature separated from the strong features. The light curve exhibits noticeable deviations from the best-fit model based on standard binary parameters. To explain the deviation, we test models including various higher-order effects of the motions of the observer, source, and lens. From this, we find that it is necessary to account for the orbital motion of the lens in describing the light curve. From modeling the light curve considering the parallax effect and Keplerian orbital motion, we are able to not only measure the physical parameters but also to find a complete orbital solution of the lens system. It is found that the event was produced by a binary lens located in the Galactic bulge with a distance of 6.7 {+-} 0.3 kpc from the Earth. The individual lens components with masses 0.9 {+-} 0.3 M{sub sun} and 0.5 {+-} 0.1 M{sub sun} are separated with a semi-major axis of a = 2.5 {+-} 1.0 AU and orbiting each other with a period P = 3.1 {+-} 1.3 yr. This event demonstrates that it is possible to extract detailed information about binary lens systems from well-resolved lensing light curves.

  12. Novel broadband glass phosphors for high CRI WLEDs.

    PubMed

    Chen, Li-Yin; Cheng, Wei-Chih; Tsai, Chun-Chin; Chang, Jin-Kai; Huang, Yi-Chung; Huang, Jhih-Ci; Cheng, Wood-Hi

    2014-05-01

    New broadband glass phosphors with excellent thermal stability were proposed and experimentally demonstrated for white light-emitting-diodes (WLEDs). The novel glass phosphors were realized through dispersing multiple phosphors into SiO₂ based glass (SiO₂-Na₂O-Al₂O₃-CaO) at 680°C. Y₃Al₅O₁₂:Ce³⁺ (YAG), Lu₃Al₅O₁₂:Ce³⁺ (LuAG), and CaAlSiN₃: Eu²⁺ (nitride) phosphor crystals were chosen respectively as the yellow, green, and red emitters of the glass phosphors. The effect of sintering temperature on inter-diffusion reduction between phosphor crystals and amorphous SiO₂ in nitride-doped glass phosphors was studied and evidenced by the aid of high-resolution transmission electron microscopy (HRTEM). Broadband glass phosphors with high quantum-yield of 55.6% were thus successfully realized through the implementation of low sintering temperature. Proof-of-concept devices utilizing the novel broadband phosphors were developed to generate high-quality cool-white light with trisstimulus coordinates (x, y) = (0.358, 0.288), color-rending index (CRI) = 85, and correlated color temperature (CCT) = 3923K. The novel broadband glass phosphors with excellent thermal stability are essentially beneficial to the applications for next-generation solid-state indoor lighting, especially in the area where high power and absolute reliability are required. PMID:24922375

  13. CHARACTERIZATION OF ACTIVATED CARBONS' PHYSICAL AND CHEMICAL PROPERTIES IN RELATION TO THEIR MERCURY ADSORPTION: SYMPOSIUM/CONFERENCE

    EPA Science Inventory

    SYMPOS/CONF NRMRL-RTP-P-597 Li*, Y.H., Lee*, C.W., and Gullett*, B.K. Characterization of Activated Carbons' Physical and Chemical Properties in Relation to their Mercury Adsorption. Carbon '01, Lexington, KY, 7/14-19/01. 2001. EPA/600/A-01/075 (NTIS PB2002- 100291). 04/05/200...

  14. PHYSICAL AND CHEMICAL CHARACTERIZATION OF INDOOR AEROSOLS RESULTING FROM THE USE OF TAP WATER IN PORTABLE HOME HUMIDIFIERS

    EPA Science Inventory

    An indoor air quality study was conducted in Boise, ID, residences to evaluate the range of aerosol concentrations that result from using tap water in portable home humidifiers and to characterize the physical and chemical properties of the humidifier aerosol. M10 concentrations ...

  15. Fabricating and Characterizing Physical Properties of Electrospun Polypeptide-based Nanofibers

    NASA Astrophysics Data System (ADS)

    Khadka, Dhan Bahadur

    This dissertation has aimed to fabricate polypeptide based biomaterial and characterize physical properties. Electrospinning is used as a tool for the sample fabrication. Project focused on determining the feasibility of electrospinning of certain synthetic polypeptides and certain elastin-like peptides from aqueous feedstocks and to characterize physical properties of polymer aqueous solution, cast film and spun fibers and fiber mats. The research involves peptide design, polymer electrospinning, fibers crosslinking, determining the extent of crosslinking, fibers protease degradation study, fibers stability and self-organization analysis, structure and composition determination by various spectroscopy and microscopy techniques and characterization of mechanical properties of individual suspended fibers. Fiber mats of a synthetic cationic polypeptide poly(L-ornithine) (PLO) and an anionic co-polypeptide of L-glutamic acid and L-tyrosine (PLEY) of defined composition have been produced by electrospinning. Fibers were obtained from polymer aqueous solution at concentrations of 20-45% (w/v) in PLO and at concentrations of 20-60% (w/v) in PLEY. Applied voltage and spinneret-collector distance were also found to influence polymer spinnability and fibers morphology. Oriented fibers were obtained by parallel electrodes geometry. Fiber diameter and morphology was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). PLO fibers exposed on glutaraldehyde (GTA) vapor rendered fiber mats water-insoluble. A common chemical reagent, carbodiimide was used to crosslink PLEY fibers. Fiber solubility in aqueous solution varied as a function of crosslinking time and crosslinker concentration. Crosslink density has been quantified by a visible-wavelength dye-based method. Degradation of crosslinked fibers by different proteases has been demonstrated. Investigation of crosslinked PLEY fibers has provided insight into the mechanisms of stability at different

  16. Effect of surface moisture on chemically bonded phosphor for thermographic phosphor thermometry

    NASA Astrophysics Data System (ADS)

    Cai, Tao; Kim, Dong; Kim, Mirae; Liu, Ying Zheng; Kim, Kyung Chun

    2016-09-01

    This study examined the effect of surface moisture on the calibration lifetime in chemically bonded phosphor paint preparation. Mg4FGeO6:Mn was used as a sensor material, which was excited by a pulsed UV LED. A high-speed camera with a frequency of 8000 Hz was used to conduct phosphor thermometry. Five samples with different degrees of surface moisture were selected during the preparation process, and each sample was calibrated 40 times at room temperature. A conventional post-processing method was used to acquire the phosphorescent lifetime for different samples with a 4  ×  4-pixel interrogation window. The measurement error and paint uniformity were also studied. The results showed that there was no obvious phosphorescence boundary between the wet parts and dry parts of phosphor paint. The lifetime increased by about 0.0345% per hour during the preparation process, showing the degree of surface moisture had almost no influence on the lifetime measurement. The lifetime changed only after annealing treatment. There was also no effect on the measurement error and uniformity. These results provide a reference for developing a real-time measurement method using thermographic phosphor thermometry. This study also provides a feasible basis for chemically bonded phosphor thermometry applications in humid and low-temperature environments.

  17. Nickel cobalt phosphorous low stress electroplating

    NASA Technical Reports Server (NTRS)

    Engelhaupt, Darell E. (Inventor); Ramsey, Brian D. (Inventor)

    2002-01-01

    An electrolytic plating process is provided for electrodepositing a nickel or nickel cobalt alloy which contains at least about 2% to 25% by atomic volume of phosphorous. The process solutions contains nickel and optionally cobalt sulfate, hypophosphorous acid or a salt thereof, boric acid or a salt thereof, a monodentate organic acid or a salt thereof, and a multidentate organic acid or a salt thereof. The pH of the plating bath is from about 3.0 to about 4.5. An electroplating process is also provided which includes electroplating from the bath a nickel or nickel cobalt phosphorous alloy. This process can achieve a deposit with high microyield of at least about 84 kg/mm.sup.2 (120 ksi) and a density lower than pure nickel of about 8.0 gm/cc. This process can be used to plate a deposit of essentially zero stress at plating temperatures from ambient to 70.degree. C.

  18. Thermal Analysis of LED Phosphor Layer

    NASA Astrophysics Data System (ADS)

    Perera, Ukwatte Lokuliyanage Indika Upendra

    Solid-state lighting technology has progressed to a level where light-emitting diode (LED) products are either on par or better than their traditional lighting technology counterparts with respect to efficacy and lifetime. At present, the most common method to create "white" light from LEDs for illumination applications is by using the LED primary radiation and wavelength-converting materials. In this method, the re-emission from the wavelength-converting materials excited by the LED primary radiation is combined with the LED primary radiation to create the "white" light. During this conversion process, heat is generated as a result of conversion inefficiencies and other loss mechanisms in the LED and the wavelength-converting materials. This generated heat, if not properly dissipated, increases the operating temperature, thereby increasing the light output degradation of the system over both the short and long term. The heat generation of the LED and thermal management of the LED have been studied extensively. Methods to effectively dissipate heat from the LEDs and maintain lower LED operating temperature are well understood. However, investigation of factors driving heat generation, the resulting temperature distribution in the phosphor layer, and the influence of the phosphor layer temperature on LED performance and reliability have not received the same focus. The goal of this dissertation was to understand the main factors driving heat and light generation and the transport of light and heat in the wavelength-converting layer of an LED system. Another goal was to understand the interaction between heat and light in the system and to develop and analyze a solution to reduce the wavelength-converting layer operating temperature, thereby improving light output and reliability. Even though past studies have explored generation and transfer separately for light and heat, to the best of the author's knowledge, this is the first study that has analyzed both factors

  19. Hydrogen migration in phosphorous doped polycrystalline silicon

    SciTech Connect

    Nickel, N.H.; Kaiser, I.

    1998-12-31

    Hydrogen diffusion in phosphorous doped polycrystalline silicon was investigated by deuterium diffusion experiments. The presence of phosphorous enhances hydrogen diffusion. For high hydrogen concentrations the activation energy of the effective diffusion-coefficient amounts to 0.25--0.35 eV. At low hydrogen concentrations diffusion is governed by deep traps that are present in an appreciable concentration of 6 {times} 10{sup 18}--10{sup 19} cm{sup {minus}3}. The hydrogen chemical-potential, {mu}{sub H}, decreases with increasing temperature at a rate of {approx}0.002 eV/K. The data are discussed in terms of a two-level model used to describe hydrogen diffusion in amorphous and undoped polycrystalline silicon.

  20. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... Defluorinated Phosphoric Acid Subcategory § 422.50 Applicability; description of the defluorinated phosphoric... defluorination of phosphoric acid. Wet process phosphoric acid is dehydrated by application of heat and...

  1. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... Defluorinated Phosphoric Acid Subcategory § 422.50 Applicability; description of the defluorinated phosphoric... defluorination of phosphoric acid. Wet process phosphoric acid is dehydrated by application of heat and...

  2. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... Defluorinated Phosphoric Acid Subcategory § 422.50 Applicability; description of the defluorinated phosphoric... defluorination of phosphoric acid. Wet process phosphoric acid is dehydrated by application of heat and...

  3. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... Defluorinated Phosphoric Acid Subcategory § 422.50 Applicability; description of the defluorinated phosphoric... defluorination of phosphoric acid. Wet process phosphoric acid is dehydrated by application of heat and...

  4. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... Defluorinated Phosphoric Acid Subcategory § 422.50 Applicability; description of the defluorinated phosphoric... defluorination of phosphoric acid. Wet process phosphoric acid is dehydrated by application of heat and...

  5. Radiological, physical, and chemical characterization of low-level alpha contaminated wastes stored at the Idaho National Engineering Laboratory

    SciTech Connect

    Apel, M.L.; Becker, G.K.; Ragan, Z.K.; Frasure, J.; Raivo, B.D.; Gale, L.G.; Pace, D.P.

    1994-03-01

    This document provides radiological, physical, and chemical characterization data for low-level alpha-contaminated radioactive and low-level alpha-contaminated radioactive and hazardous (i.e., mixed) wastes stored at the Idaho National Engineering Laboratory and considered for treatment under the Private Sector Participation Initiative Program. Waste characterization data are provided in the form of INEL Waste Profile Sheets. These documents provide, for each content code, information on waste identification, waste description, waste storage configuration, physical/chemical waste composition, radionuclide and associated alpha activity waste characterization data, and hazardous constituents present in the waste. Information is provided for 97 waste streams which represent an estimated total volume of 25,450 m 3 corresponding to a total mass of approximately 12,000,000 kg. In addition, considerable information concerning alpha, beta, gamma, and neutron source term data specific to Rocky Flats-generated waste forms stored at the INEL are provided to assist in facility design specification.

  6. Blue, yellow and orange color emitting rare earth doped BaCa2Al8O15 phosphors prepared by combustion method

    NASA Astrophysics Data System (ADS)

    Yerpude, A. N.; Dhoble, S. J.; Reddy, B. Sudhakar

    2014-12-01

    Eu2+, Dy3+, Sm3+ activated BaCa2Al8O15 phosphors were prepared by the combustion method. The phosphor powders were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and photoluminescence (PL) spectrophotometer. Photoluminescence spectra of BaCa2Al8O15:Eu2+ phosphors show emission wavelength at 435 nm that corresponds to 4f65d1→4f7 transition of Eu2+ ion by keeping excitation wavelength extending broad-band from 270 to 400 nm centered at 334 nm. The Dy3+ doped BaCa2Al8O15 phosphors shows blue emission (485 nm) and yellow emission (566 nm) under the excitation of 347 nm, corresponding to the 4F9/2→6H15/2 transition and 4F9/2→6H13/2 transition of Dy3+ ions, respectively. The Sm3+ doped BaCa2Al8O15 phosphors have shown strong orange emission at 604 nm corresponding to the 4G5/2→6H7/2 transition of Sm3+ with intense excitation wavelength at 406 nm. Scanning electron microscopy has been used for exploring the size and morphological properties of the prepared phosphors. The obtained results show that the phosphors have potential application in the field of solid state lighting.

  7. Structural and optical analysis on europium doped AZrO3 (A=Ba, Ca, Sr) phosphor for display devices application

    NASA Astrophysics Data System (ADS)

    Dubey, Vikas; Tiwari, Neha

    2016-05-01

    Behavior displayed by europium doped AZrO3 phosphor which was synthesized by solid state reaction method. For synthesis of BaZrO3, SrZrO3 and CaZrO3 phosphor with fixed concentration of europium ion was calcination at 1000°C and sintered at 1300°C following intermediate grinding. Synthesized sample was characterized by X-ray diffraction analysis and crystallite sized was calculated by Scherer's formula. From PL spectra of prepared phosphors shows intense emission centred at 612nm (red emission) with high intensity for SrZrO3:Eu3+. For europium doped BaZrO3 and CaZrO3 (613nm) phosphor shows less intense PL spectra as compared to SrZrO3:Eu3+. The strong emission peak of AZrO3:Eu3+ phosphor is due to forced electric dipole transition of 5D0 to 7F2 centered at 612 and 613nm. It is characteristic red emission for europium ion. The excitation spectra of AZrO3:Eu3+ phosphor mainly consists of the charge transfer and (CTB) of Eu3+ located in 200-350 nm centred at 254nm. The present phosphors can act as single host for red light emission in display devices. The CIE coordinates were calculated by Spectrophotometric method using the spectral energy distribution of the AZrO3:Eu3+ sample.

  8. Synthesis and TL/OSL properties of a novel high-sensitive blue-emitting LiSrPO4:Eu2+ phosphor for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Palan, C. B.; Koparkar, K. A.; Bajaj, N. S.; Soni, A.; Omanwar, S. K.

    2016-07-01

    In this study, a series of Eu2+-doped LiSrPO4 phosphors were synthesized via solid-state method. The structural and morphological characterizations were done through X-ray diffraction and scanning electronic microscope. Additionally, the photoluminescence (PL), thermoluminescence (TL) and optically stimulated luminescence (OSL) behaviours of LiSrPO4:Eu2+ phosphors were studied. The LiSrPO4:Eu2+ phosphor shows OSL sensitivity about 8 times than that of α-Al2O3:C phosphor and 6 times than that of LiMgPO4:Tb3+, B phosphor. Moreover, TL sensitivity was about 15 times more as compared to α-Al2O3:C phosphor. The kinetic parameters of TL curve were calculated using peak shape method. In TL/OSL mode, dose-response was almost linear nature, in the range of measurement. The minimum detectable dose was found to be 25.18 μGy with 3 σ of background. Also, reusability was also studies, which shows the phosphor can be reusable for 10 cycles with 0.1 % change in OSL output.

  9. A dual-emitting core-shell carbon dot-silica-phosphor composite for white light emission

    NASA Astrophysics Data System (ADS)

    Chen, Yonghao; Lei, Bingfu; Zheng, Mingtao; Zhang, Haoran; Zhuang, Jianle; Liu, Yingliang

    2015-11-01

    A unique dual-emitting core-shell carbon dot-silica-phosphor (CDSP) was constructed from carbon dots (CDs), tetraethoxysilane (TEOS) and Sr2Si5N8:Eu2+ phosphor through a one-pot sol-gel method. Blue emitting CDs uniformly disperse in the silica layer covering the orange emitting phosphor via a polymerization process, which makes CDSP achieve even white light emission. Tunable photoluminescence of CDSP is observed and the preferable white light emission is achieved through changing the excitation wavelength or controlling the mass ratio of the phosphor. When CDSP powders with a phosphor rate of 3.9% and 5.1% are excited at a wavelength of 400 nm, preferable white light emission is observed, with Commission Internationale de l'Eclairage (CIE) coordinates of (0.32, 0.32) and (0.34, 0.32), respectively. Furthermore, CDSP can mix well with epoxy resin to emit strong and even white light, and based on this, a CDSP-based white LED with a high colour rendering index (CRI) of 94 was fabricated.A unique dual-emitting core-shell carbon dot-silica-phosphor (CDSP) was constructed from carbon dots (CDs), tetraethoxysilane (TEOS) and Sr2Si5N8:Eu2+ phosphor through a one-pot sol-gel method. Blue emitting CDs uniformly disperse in the silica layer covering the orange emitting phosphor via a polymerization process, which makes CDSP achieve even white light emission. Tunable photoluminescence of CDSP is observed and the preferable white light emission is achieved through changing the excitation wavelength or controlling the mass ratio of the phosphor. When CDSP powders with a phosphor rate of 3.9% and 5.1% are excited at a wavelength of 400 nm, preferable white light emission is observed, with Commission Internationale de l'Eclairage (CIE) coordinates of (0.32, 0.32) and (0.34, 0.32), respectively. Furthermore, CDSP can mix well with epoxy resin to emit strong and even white light, and based on this, a CDSP-based white LED with a high colour rendering index (CRI) of 94 was fabricated

  10. Phosphoric Acid Fuel Cell Technology Status

    NASA Technical Reports Server (NTRS)

    Simons, S. N.; King, R. B.; Prokopius, P. R.

    1981-01-01

    A review of the current phosphoric acid fuel cell system technology development efforts is presented both for multimegawatt systems for electric utility applications and for multikilowatt systems for on-site integrated energy system applications. Improving fuel cell performance, reducing cost, and increasing durability are the technology drivers at this time. Electrodes, matrices, intercell cooling, bipolar/separator plates, electrolyte management, and fuel selection are discussed.

  11. High Temperature Thermographic Phosphor Coatings Development

    NASA Technical Reports Server (NTRS)

    Goedeke, Shawn; Allison, S. W.; Beshears, D. L.; Bencic, T.; Cates, M. R.; Hollerman, W. A.; Guidry, R.

    2003-01-01

    For many years, phosphor thermometry has been used for non-contact temperature measurements. A large number of applications have been associated with high temperatures, especially for aerospace systems where blackbody radiation backgrounds are large and in challenging environments, such as vibration, rotation, flame, or noise. These environments restrict the use of more common thermocouples or infrared thermometric techniques. In particular, temperature measurements inside jet turbines, rocket engines, or similar devices are especially amenable to phosphor techniques. Often the fluorescent materials are used as powders, either suspended in binders and applied like paint or applied as high-temperature sprays. Thin coatings that are less than 50 m thick are used on the surfaces of interest. These coatings will quickly assume the same temperature as the surface to which they are applied. The temperature dependence of fluorescent materials is a function of the base matrix atoms and a small quantity of added activator or dopant ions. Often for high temperature applications, the selected materials are refractory and include rare earth ions. Phosphors like Y3Al5O12 (YAG) doped with Eu, Dy, or Tm, Y2O3 doped with Eu, or similar rare earth compounds, will survive high temperatures and can be configured to emit light that changes rapidly in lifetime and intensity. For example, researchers at Oak Ridge National Laboratory recently observed fluorescence from YAG:Dy and YAG:Tm at temperatures above 1400 C. One of the biggest challenges is to locate a binder material that can withstand tremendous variations in temperature in an adverse aerospace environment. This poster will provide an overview into our attempt to utilize phosphors for thermometry purposes. Emphasis will be placed on the use of selected binder materials that can withstand high temperatures. This research was completed for the National Aeronautics and Space Administration's Glenn Research Center in Cleveland

  12. Sorohalide scintillators, phosphors, and uses thereof

    DOEpatents

    Yang, Pin; Deng, Haoran; Doty, F. Patrick; Zhou, Xiaowang

    2016-05-10

    The present invention relates to sorohalide compounds having formula A.sub.3B.sub.2X.sub.9, where A is an alkali metal, B is a rare earth metal, and X is a halogen. Optionally, the sorohalide includes a dopant D. Such undoped and doped sorohalides are useful as scintillation materials or phosphors for any number of uses, including for radiation detectors, solid-state light sources, gamma-ray spectroscopy, medical imaging, and drilling applications.

  13. Phosphor Thermometry of Gas Turbine Surfaces

    SciTech Connect

    Allison, Steven W.; Beshears, David L.; Cates, Michael R.; Noel, Bruce W.; Turley, W. D.

    1995-12-31

    This paper describes a nondestructive method for thermometry applicable to ceramic surfaces and coatings. To date our primary application has been to turbine engine and air vehicle surfaces. This method makes use of thermally sensitive phosphors many of which, as it turns out, are also ceramics. These materials fluoresce when suitably illuminated by ultraviolet light. The fluorescence intensity and decay time are well-behaved functions of temperature and therefore serve as reliable indicators of the temperature of the substrate to which the fluorescing material is attached. It is a non- contact method in that the light delivery and collection optics can be remotely located. A range of phosphor materials have been tested and any temperature ranging from 8 to 1900 K can be measured by selection of the appropriate phosphor. Turbine blades, vanes, thermal barrier coatings, and panels are examples of surfaces which have been diagnosed to date in either engine or engine-simulation facilities. A variety of coating methods are used, including electron-beam deposition, radio-frequency sputtering, and curing with inorganic binders. This paper summarizes the results to date and status of this technology.

  14. Thermal history sensing with thermographic phosphors

    NASA Astrophysics Data System (ADS)

    Heyes, A. L.; Rabhiou, A.; Feist, J. P.; Kempf, A.

    2013-09-01

    The ability to measure temperatures on high thermal loaded components in gas turbines and similar prime movers is critical during the design phase if the performance of cooling strategies is to be confirmed. Restricted access and the extreme environment mean that on-line temperature measurement is not always possible and that off-line temperature techniques employing thermal history sensors are sometimes necessary. The authors have developed a new type of sensor based on ceramic phosphors. These show bright narrow band emission that is easily detected and distinguished from the background. Crystallization, phase change and diffusion are all temperature dependent processes that affect the emission characteristics and that, with proper calibration, can be used to form a phosphor based thermal history sensor. Results from the calibration of crystallization in Y2SiO5:Tb and its application in the form of a temperature indicating paint are reviewed. A new embodiment of the phosphor thermal history sensor concept is then presented comprising a YSZ/YAG:Dy composite applied using air plasma spraying in the form of a thermal barrier coating. The coating is shown to function as a thermal history sensor albeit with a limited dynamic range.

  15. A novel phosphoric acid doped poly(ethersulphone)-poly(vinyl pyrrolidone) blend membrane for high-temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Xu, Xin; Wang, Haining; Lu, Shanfu; Guo, Zhibin; Rao, Siyuan; Xiu, Ruijie; Xiang, Yan

    2015-07-01

    A high-temperature proton exchange membrane, poly(ethersulphone)-poly(vinyl pyrrolidone) (PES-PVP) blend membrane is successfully prepared by scalable polymer blending method. The physical properties of blend membrane are characterized by DSC, TG and tensile strength test. The DSC and TG results indicate PES-PVP blend membranes possess excellent thermal stability. After phosphoric acid (PA) doping treatment, the blend membrane shows enhanced proton conductivity. PA doping level and volume swelling ratio of the blend membrane are found to be positively related to the PVP content. A high proton conductivity of 0.21 S/cm is achieved at 180 °C for PA doped PES-PVP 80% with a PA doping level of 9.1. PEM fuel cell based on PA doped PES-PVP 80% membrane shows a high power density of 850 mW/cm2 and outstanding stability at 180 °C without extra humidification.

  16. Assessment of the environmental aspects of the DOE phosphoric acid fuel cell program

    NASA Technical Reports Server (NTRS)

    Lundblad, H. L.; Cavagrotti, R. R.

    1983-01-01

    The likely facets of a nationwide phosphoric acid fuel cell (PAFC) power plant commercial system are described. The beneficial and adverse environmental impacts produced by the system are assessed. Eleven specific system activities are characterized and evaluated. Also included is a review of fuel cell technology and a description of DOE's National Fuel Cell Program. Based on current and reasonably foreseeable PAFC characteristics, no environmental or energy impact factor was identified that would significantly inhibit the commercialization of PAFC power plant technology.

  17. Phosphorous and aluminum gettering in Silicon-Film{trademark} Product II material

    SciTech Connect

    Cotter, J.E.; Barnett, A.M.; Hall, R.B.

    1995-08-01

    Gettering processes are being developed for the Silicon-Film{trademark} Product II solar cell structure. These processes have been developed specifically for films of silicon grown on dissimilar substrates with barrier layers. Gettering with both phosphorous- and aluminum-based processing sequences has resulted in enhancement of minority carrier diffusion length. Long diffusion lengths have allowed the characterization of light trapping in thin films of silicon grown on barrier-coated substrates.

  18. Fuel Thermo-physical Characterization Project. Fiscal Year 2014 Final Report

    SciTech Connect

    Burkes, Douglas; Casella, Andrew M.; Buck, Edgar C.; Casella, Amanda J.; Edwards, Matthew K.; MacFarlan, Paul J.; Pool, Karl N.; Slonecker, Bruce D.; Smith, Frances N.; Steen, Franciska H.

    2015-03-15

    The Office of Material Management and Minimization (M3) Reactor Conversion Fuel Thermo-Physical Characterization Project at Pacific Northwest National Laboratory (PNNL) was tasked with using PNNL facilities and processes to receive irradiated low enriched uranium–molybdenum (LEU-Mo) fuel plate samples and perform analysis in support of the M3 Reactor Conversion Program. This work is in support of the M3 Reactor Conversion Fuel Development Pillar that is managed by Idaho National Laboratory. The primary research scope was to determine the thermo-physical properties as a function of temperature and burnup. Work conducted in Fiscal Year (FY) 2014 complemented measurements performed in FY 2013 on four additional irradiated LEU-Mo fuel plate samples. Specifically, the work in FY 2014 investigated the influence of different processing methods on thermal property behavior, the absence of aluminum alloy cladding on thermal property behavior for additional model validation, and the influence of higher operating surface heat flux / more aggressive irradiation conditions on thermal property behavior. The model developed in FY 2013 and refined in FY 2014 to extract thermal properties of the U-Mo alloy from the measurements conducted on an integral fuel plate sample (i.e., U-Mo alloy with a thin Zr coating and clad in AA6061) continues to perform very well. Measurements conducted in FY 2014 on samples irradiated under similar conditions compare well to measurements performed in FY 2013. In general, there is no gross influence of fabrication method on thermal property behavior, although the difference in LEU-Mo foil microstructure does have a noticeable influence on recrystallization of grains during irradiation. Samples irradiated under more aggressive irradiation conditions, e.g., higher surface heat flux, revealed lower thermal conductivity when compared to samples irradiated at moderate surface heat fluxes, with the exception of one sample. This report documents thermal

  19. Characterizing Physical Habitat of a Mixed-Land Use Stream of the Central U.S.

    NASA Astrophysics Data System (ADS)

    Hooper, L. W.; Hubbart, J. A.; Hosmer, G. W.; Hogan, M. L.

    2014-12-01

    Land use altered flow regime impacts on aquatic biological habitat can be quantified by means of a physical habitat assessment (PHA). PHA metrics include (but are not limited to) channel substrate, width and wetted width, bank slope, and bank height. Hinkson Creek, located in Boone County, Missouri, was placed on the Missouri Department of Natural Resources list of impaired waters (Section 303d) of the Clean Water Act in 1998. A physical habitat assessment of Hinkson Creek in 2014 provides quantitative data characterizing the current potential of Hinkson Creek to fully support aquatic life, specifically macroinvertebrates (a goal for delisting). The PHA was conducted every 100m of Hinkson Creek (56km). Results from the lower 87.9% (contiguous) of the drainage indicate channel width ranged from a maximum of 70m to a minimum of 4.6m, with a mean width of 17m and standard deviation (SD) of 7.4m. Bankfull width ranged from a maximum of 74m to a minimum of 8.8m (mean = 26.1m, SD = 8.2). Bank height ranged from a maximum of 5.8m to a minimum of 0.4m (mean = 2.9m, SD = 1m). Mean bank angle for the left and right banks was nearly equivalent (left = 33.8°, right = 34.6°). Bank height and bankfull width increased with increasing drainage distance. Trench pools were the dominant channel unit at 71.4% of the sample transects, while riffles were present at 16.6%. Analysis of stream channel bed composition was conducted using a modified Wolman pebble count survey at each site and Thalweg profile between sites. Size class results were quantified as follows: 56.1% fines (16mm or less), 36.2% intermediate (16mm to 1000mm, plus vegetation and wood), 8.7% large/bedrock (greater than 1000mm, riprap and bedrock). Study results provide science-based information to better equip land planners in Hinkson Creek watershed and similar multi-use watersheds of the central United States for future management decisions and development scenarios.

  20. Characterizing the physical properties of solidified PEG, an analog for basaltic lava crust

    NASA Astrophysics Data System (ADS)

    Soule, S. A.; Cashman, K.; Rust, A.

    2001-12-01

    The crust of a basaltic lava flow provides significant resistance to flow and is an important indicator of lava flow dynamics. Analog studies using polyethylene glycol (PEG), such as those by Fink and Griffiths (1990) and Griffiths and Fink (1992), are a useful means to determine the conditions under which different crustal morphologies are produced. To accurately apply the results of these studies to natural systems, we must understand how to scale between basaltic lava and its analog, PEG. The long-term goal of our study is to characterize the physical properties of both materials for the purpose of developing scaling relationships. We have designed a set of experiments to determine the strength and viscosity of solidified PEG. We measure the ductile deformation and failure of PEG under tension and in simple shear. Experiments are conducted with either constant stress or constant strain rate and at a range of temperatures (5 to 25 \\deg C). Tension experiments are conducted on hourglass-shaped PEG casts with failure occurring at the midpoint of the hourglass. Tension is produced by hanging weight (constant stress) or by pulling with a DC servo motor (constant strain rate). Simple shear experiments are conducted by turning a gear frozen into a sheet of PEG. A thinned ring of crust centered around the gear controls the failure location. From constant stress experiments, we measure pre-failure ductile deformation of the PEG to determine its viscosity. Constant strain rate experiments allow us to determine the dependence of PEG strength on strain rate. To determine the physical properties of basaltic crust we are building a furnace capable of melting large quantities of basalt and conducting experiments at high temperature. The experiments conducted on PEG will aid in the design of similar experiments on lava. The results of this study will have applications beyond scaling between analog models and natural systems. The presence or absence of a continuous flow crust

  1. SELECTION AND MEASUREMENT OF PHYSICAL PROPERTIES FOR CHARACTERIZATION OF CHEMICAL PROTECTIVE CLOTHING MATERIALS

    EPA Science Inventory

    Chemical protective clothing (CPC) must possess certain physical properties if it is to function as an effective barrier to chemicals. he physical characteristics of CPC materials has gone largely unstudied; most attention has been focussecd on chemical resistance. hysical proper...

  2. Advances in Phosphors for Light-emitting Diodes.

    PubMed

    Lin, Chun Che; Liu, Ru-Shi

    2011-06-01

    Light-emitting diodes (LEDs) are excellent candidates for general lighting because of their rapidly improving efficiency, durability, and reliability, their usability in products of various sizes, and their environmentally friendly constituents. Effective lighting devices can be realized by combining one or more phosphor materials with chips. Accordingly, it is very important that the architecture of phosphors be developed. Although numerous phosphors have been proposed in the past several years, the range of phosphors that are suitable for LEDs is limited. This work describes recent progress in our understanding of the prescription, morphology, structure, spectrum, and packaging of such phosphors. It suggests avenues for further development and the scientific challenges that must be overcome before phosphors can be practically applied in LEDs. PMID:26295420

  3. Site Characterization of the Source Physics Experiment Phase II Location Using Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Sexton, E. A.; Snelson, C. M.; Chipman, V.; Emer, D. F.; White, R. L.; Emmitt, R.; Wright, A. A.; Drellack, S.; Huckins-Gang, H.; Mercadante, J.; Floyd, M.; McGowin, C.; Cothrun, C.; Bonal, N.

    2013-12-01

    An objective of the Source Physics Experiment (SPE) is to identify low-yield nuclear explosions from a regional distance. Low-yield nuclear explosions can often be difficult to discriminate among the clutter of natural and man-made explosive events (e.g., earthquakes and mine blasts). The SPE is broken into three phases. Phase I has provided the first of the physics-based data to test the empirical models that have been used to discriminate nuclear events. The Phase I series of tests were placed within a highly fractured granite body. The evolution of the project has led to development of Phase II, to be placed within the opposite end member of geology, an alluvium environment, thereby increasing the database of waveforms to build upon in the discrimination models. Both the granite and alluvium sites have hosted nearby nuclear tests, which provide comparisons for the chemical test data. Phase III of the SPE is yet to be determined. For Phase II of the experiment, characterization of the location is required to develop the geologic/geophysical models for the execution of the experiment. Criteria for the location are alluvium thickness of approximately 170 m and a water table below 170 m; minimal fracturing would be ideal. A P-wave mini-vibroseis survey was conducted at a potential site in alluvium to map out the subsurface geology. The seismic reflection profile consisted of 168 geophone stations, spaced 5 m apart. The mini-vibe was a 7,000-lb peak-force source, starting 57.5 m off the north end of the profile and ending 57.5 m past the southern-most geophone. The length of the profile was 835 m. The source points were placed every 5 m, equally spaced between geophones to reduce clipping. The vibroseis sweep was from 20 Hz down to 180 Hz over 8 seconds, and four sweeps were stacked at each shot location. The shot gathers show high signal-to-noise ratios with clear first arrivals across the entire spread and the suggestion of some shallow reflectors. The data were

  4. Physical-biopolymer characterization of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) blended with natural rubber latex

    NASA Astrophysics Data System (ADS)

    Kuntanoo, K.; Promkotra, S.; Kaewkannetra, P.

    2015-03-01

    A biopolymer of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is blended with bio-based materials, natural rubber latex, to improve their microstructures. The various ratios between PHBV and natural rubber latex are examined to develop their mechanical properties. In general, physical properties of PHBV are hard, brittle and low flexible while natural rubber (NR) is presented itself as high elastic materials. Concentrations of the PHBV solution are constituted at 1%, 2% and 3% (w/v). The mixtures of their PHBV solutions to natural rubber latex are produced the blended films in three different ratios of 4:6, 5:5 and 6:4, respectively. They are characterized by appearance analyses which are the scanning electron microscope (SEM), universal testing machine (UTM) and differential scanning calorimetry (DSC). The SEM photomicrographs of the blended films and the controlled PHBV can provide the void distribution in the range of 12-14% and 19-21%, respectively. For mechanical properties of the blended films, the various elastic moduli of 1%, 2% and 3% (w/v) PHBV are the average of 773, 956 and 1,007 kPa, respectively. The tensile strengths of the blends increase with the increased concentrations of PHBV, similarly trend to the elastic modulus. The crystallization and melting behavior of unmixed PHBV and the blends are determined by DSC. Melting transition temperatures (Tm) of the unmixed PHBV are stated two melting peak at 154°C and 173°C. Besides, the melting peaks of the blends alter in the range of 152-156°C and 168-171°C, respectively. According to morphology of the blends, the void distribution decreases twice compared to the unmixed PHBV. The results of mechanical properties and thermal analysis indicate that the blended PHBV can be developed their properties by more resilient and wide range of temperature than usual.

  5. Physical characterization of tin composite oxides and related anode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Goward, Gillian Ruth

    2000-10-01

    This thesis addresses the issues concerning the excellent electrochemical performance exhibited by the tin-composite-oxide glass, Sn1.0Al 0.42B0.56P0.40O3.6 as an anode material for rechargeable lithium ion batteries. The debate surrounding this material focuses on the nature of the lithium-tin interaction; whether it is ionic or intermetallic. The TCO anode material has been studied electrochemically, as well as by multinuclear Solid-State-NMR, X-ray Absorption Spectroscopy, and X-ray Scattering including Pair Distribution Function analysis. By examining electrode materials at various stages of discharge, corresponding to various levels of lithium insertion, the interactions between lithium, tin, oxygen, and the other components of the glass have been ascertained. The inserted lithium remains highly ionic throughout the first cycle of the cell, with no evidence for the formation of alloy phases. Extended cycling of the cell results in the formation of alloy-like domains in the parent material, SnO, but not in the case of TCO. This demonstrates that the required structural rearrangements for the formation of Li-Sn phases are kinetically prohibited; and this to a greater extend in TCO than in SnO. Two key factors account for the electrochemical properties of TCO: (1) the participation of the glass framework in sequestering the electrochemically active tin centers and providing a flexible framework for the reversible insertion of lithium; (2) the proximity of oxygen to tin is maintained throughout lithium insertion process, thus oxygen may act as a charge carrier. These factors are developed in the context of several models for the interactions in the electrode, drawing on the data obtained from the physical characterizations implemented here. A comparative study of the anode material NaMoO3 is also described.

  6. Physical-biopolymer characterization of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) blended with natural rubber latex

    SciTech Connect

    Kuntanoo, K.; Promkotra, S.; Kaewkannetra, P.

    2015-03-30

    A biopolymer of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is blended with bio-based materials, natural rubber latex, to improve their microstructures. The various ratios between PHBV and natural rubber latex are examined to develop their mechanical properties. In general, physical properties of PHBV are hard, brittle and low flexible while natural rubber (NR) is presented itself as high elastic materials. Concentrations of the PHBV solution are constituted at 1%, 2% and 3% (w/v). The mixtures of their PHBV solutions to natural rubber latex are produced the blended films in three different ratios of 4:6, 5:5 and 6:4, respectively. They are characterized by appearance analyses which are the scanning electron microscope (SEM), universal testing machine (UTM) and differential scanning calorimetry (DSC). The SEM photomicrographs of the blended films and the controlled PHBV can provide the void distribution in the range of 12-14% and 19-21%, respectively. For mechanical properties of the blended films, the various elastic moduli of 1%, 2% and 3% (w/v) PHBV are the average of 773, 956 and 1,007 kPa, respectively. The tensile strengths of the blends increase with the increased concentrations of PHBV, similarly trend to the elastic modulus. The crystallization and melting behavior of unmixed PHBV and the blends are determined by DSC. Melting transition temperatures (T{sub m}) of the unmixed PHBV are stated two melting peak at 154°C and 173°C. Besides, the melting peaks of the blends alter in the range of 152-156°C and 168-171°C, respectively. According to morphology of the blends, the void distribution decreases twice compared to the unmixed PHBV. The results of mechanical properties and thermal analysis indicate that the blended PHBV can be developed their properties by more resilient and wide range of temperature than usual.

  7. Physical characterization of a prototype selenium-based full field digital mammography detector.

    PubMed

    Saunders, Robert S; Samei, Ehsan; Jesneck, Jonathan L; Lo, Joseph Y

    2005-02-01

    The purpose of this study was to measure experimentally the physical performance of a prototype mammographic imager based on a direct detection, flat-panel array design employing an amorphous selenium converter with 70 microm pixels. The system was characterized for two different anode types, a molybdenum target with molybdenum filtration (Mo/Mo) and a tungsten target with rhodium filtration (W/Rh), at two different energies, 28 and 35 kVp, with approximately 2 mm added aluminum filtration. To measure the resolution, the presampled modulation transfer function (MTF) was measured using an edge method. The normalized noise power spectrum (NNPS) was measured by two-dimensional Fourier analysis of uniformly exposed mammograms. The detective quantum efficiencies (DQEs) were computed from the MTFs, the NNPSs, and theoretical ideal signal to noise ratios. The MTF was found to be close to its ideal limit and reached 0.2 at 11.8 mm(-1) and 0.1 at 14.1 mm(-1) for images acquired at an RQA-M2 technique (Mo/Mo anode, 28 kVp, 2 mm Al). Using a tungsten technique (MW2; W/Rh anode, 28 kVp, 2 mm Al), the MTF went to 0.2 at 11.2 mm(-1) and to 0.1 at 13.3 mm(-1). The DQE reached a maximum value of 54% at 1.35 mm(-1) for the RQA-M2 technique at 1.6 microC/kg and achieved a peak value of 64% at 1.75 mm(-1) for the tungsten technique (MW2) at 1.9 microC/kg. Nevertheless, the DQE showed strong exposure and frequency dependencies. The results indicated that the detector offered high MTFs and DQEs, but structured noise effects may require improved calibration before clinical implementation. PMID:15789606

  8. PHYSICAL CHARACTERIZATION AND ORIGIN OF BINARY NEAR-EARTH ASTEROID (175706) 1996 FG{sub 3}

    SciTech Connect

    Walsh, Kevin J.; Delbo, Marco; Mueller, Michael; Binzel, Richard P.; DeMeo, Francesca E.

    2012-04-01

    The near-Earth asteroid (NEA) (175706) 1996 FG{sub 3} is a particularly interesting spacecraft target: a binary asteroid with a low-{Delta}v heliocentric orbit. The orbit of its satellite has provided valuable information about its mass density while its albedo and colors suggest it is primitive or part of the C-complex taxonomic grouping. We extend the physical characterization of this object with new observations of its emission at mid-infrared wavelengths and with near-infrared reflection spectroscopy. We derive an area-equivalent system diameter of 1.90 {+-} 0.28 km (corresponding to approximate component diameters of 1.83 km and 0.51 km, respectively) and a geometric albedo of 0.039 {+-} 0.012. (175706) 1996 FG{sub 3} was previously classified as a C-type asteroid, though the combined 0.4-2.5 {mu}m spectrum with thermal correction indicates classification as B-type; both are consistent with the low measured albedo. Dynamical studies show that (175706) 1996 FG{sub 3} most probably originated in the inner main asteroid belt. Recent work has suggested the inner Main Belt (142) Polana family as the possible origin of another low-{Delta}v B-type NEA, (101955) 1999 RQ{sub 36}. A similar origin for (175706) 1996 FG{sub 3} would require delivery by the overlapping Jupiter 7:2 and Mars 5:9 mean motion resonances rather than the {nu}{sub 6}, and we find this to be a low probability, but possible, origin.

  9. High-k dielectrics on (100) and (110) n-InAs: Physical and electrical characterizations

    SciTech Connect

    Wang, C. H. Hsu, W. C.; Doornbos, G.; Astromskas, G.; Vellianitis, G.; Oxland, R.; Holland, M. C.; Passlack, M.; Huang, M. L.; Lin, C. H.; Hsieh, C. H.; Chang, Y. S.; Lee, T. L.; Chen, Y. Y.; Diaz, C. H.; Ramvall, P.; Lind, E.; Wernersson, L.-E.; Droopad, R.

    2014-04-15

    Two high-k dielectric materials (Al{sub 2}O{sub 3} and HfO{sub 2}) were deposited on n-type (100) and (110) InAs surface orientations to investigate physical properties of the oxide/semiconductor interfaces and the interface trap density (D{sub it}). X-ray photoelectron spectroscopy analyses (XPS) for native oxides of (100) and (110) as-grown n-InAs epi wafers show an increase in As-oxide on the (100) surface and an increase in InOx on the (110) surface. In addition, XPS analyses of high-k (Al{sub 2}O{sub 3} and HfO{sub 2}) on n-InAs epi show that the intrinsic native oxide difference between (100) and (110) epi surfaces were eliminated by applying conventional in-situ pre-treatment (TriMethyAluminium (TMA)) before the high-k deposition. The capacitance-voltage (C-V) characterization of HfO{sub 2} and Al{sub 2}O{sub 3} MOSCAPs on both types of n-InAs surfaces shows very similar C-V curves. The interface trap density (D{sub it}) profiles show D{sub it} minima of 6.1 × 10{sup 12}/6.5 × 10{sup 12} and 6.6 × 10{sup 12}/7.3 × 10{sup 12} cm{sup −2} eV{sup −1} for Al{sub 2}O{sub 3} and HfO{sub 2}, respectively for (100) and (110) InAs surfaces. The similar interface trap density (D{sub it}) on (100) and (110) surface orientation were observed, which is beneficial to future InAs FinFET device with both (100) and (110) surface channel orientations present.

  10. Evaluating thermographic phosphors in an operating turbine engine

    SciTech Connect

    Noel, B.W.; Borella, H.M. ); Lewis, W.; Turley, W.D. ); Beshears, D.L.; Capps, G.J.; Cates, M.R.; Muhs, J.D.; Tobin, K.W. )

    1989-01-01

    The results of a field test in a commercial turbine engine showed that we can remotely measure the temperature of engine components in operating engines using thermographic phosphors. The remote- measurement method exploits the temperature dependence of the characteristic decay time of the laser-induced fluorescence of thermographic phosphors. This paper summarizes recent work leading up to and including a successful test of the thermographic-phosphor method in an operating turbine engine. 6 refs., 7 figs.

  11. Phosphor Systems for Illumination Quality Solid State Lighting Products

    SciTech Connect

    Setlur, Anant; Briel, Linda; Cleaver, Robert; Clothier, Brent; Gao, Yan; Harlow, Richard; Henderson, Claire; Heward, William; Hill, M Christine; Lyons, Robert; Murphy, James; Siclovan, Oltea; Stoklosa, Stan; Happek, Uwe; Aanegola, Srinath; Aesram, Danny; Deshpande, Anirudha; Jacob, Cherian; Kolodin, Boris; Stoklosa, Emil; Beers, Williams

    2010-03-31

    The objective of this program is to develop phosphor systems that will enable LED lamps with 96 lm/W efficacy at correlated color temperatures, (CCTs) ~3000 K, and color rendering indices (CRIs) >80 and 71 lm/W efficacy at CCT<3100 K and CRI~95 using phosphor downconversion of LEDs. This primarily involves the invention and development of new phosphor materials that have improved efficiency and better match the eye sensitivity curves.

  12. Luminescence studies and infrared emission of erbium-doped calcium zirconate phosphor.

    PubMed

    Tiwari, Neha; Dubey, Vikas

    2016-05-01

    The near-infrared-to-visible upconversion luminescence behaviour of Er(3+) -doped CaZrO3 phosphor is discussed in this manuscript. The phosphor was prepared by a combustion synthesis technique that is suitable for less-time-taking techniques for nanophosphors. The starting materials used for sample preparation were Ca(NO3 )2 .4H2 O, Zr(NO3 )4 and Er(NO3 )2, and urea was used as a fuel. The prepared sample was characterized by X-ray diffraction (XRD). The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM). The functional group analysis was determined by Fourier transform infrared (FTIR) spectroscopy. All prepared phosphors with variable Er(3+) concentrations (0.5-2.5 mol%) were studied by photoluminescence analysis. It was found that the excitation spectra of the prepared phosphor showed a sharp excitation peak centred at 980 nm. The emission spectra with variable Er(3+) concentrations showed strong peaks in the 555 nm and 567 nm range, with a dominant peak at 555 nm due to the ((2) H11/2 ,(4) S3/2 ) transition and a weaker transition at 567 nm associated with 527 nm. Spectrophotometric determination of the peak was evaluated by the Commission Internationale de I'Eclairage (CIE) method These upconverted emissions were attributed to a two-photon process. The excitation wavelength dependence of the upconverted luminescence, together with its time evolution after infrared pulsed excitation, suggested that energy transfer upconversion processes were responsible for the upconversion luminescence. The upconversion mechanisms were studied in detail through laser power dependence. Excited state absorption and energy transfer processes were discussed as possible upconversion mechanisms. The cross-relaxation process in Er(3+) was also investigated. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26456020

  13. Multi-physics and multi-scale characterization of shale anisotropy

    NASA Astrophysics Data System (ADS)

    Sarout, J.; Nadri, D.; Delle Piane, C.; Esteban, L.; Dewhurst, D.; Clennell, M. B.

    2012-12-01

    Shales are the most abundant sedimentary rock type in the Earth's shallow crust. In the past decade or so, they have attracted increased attention from the petroleum industry as reservoirs, as well as more traditionally for their sealing capacity for hydrocarbon/CO2 traps or underground waste repositories. The effectiveness of both fundamental and applied shale research is currently limited by (i) the extreme variability of physical, mechanical and chemical properties observed for these rocks, and by (ii) the scarce data currently available. The variability in observed properties is poorly understood due to many factors that are often irrelevant for other sedimentary rocks. The relationships between these properties and the petrophysical measurements performed at the field and laboratory scales are not straightforward, translating to a scale dependency typical of shale behaviour. In addition, the complex and often anisotropic micro-/meso-structures of shales give rise to a directional dependency of some of the measured physical properties that are tensorial by nature such as permeability or elastic stiffness. Currently, fundamental understanding of the parameters controlling the directional and scale dependency of shale properties is far from complete. Selected results of a multi-physics laboratory investigation of the directional and scale dependency of some critical shale properties are reported. In particular, anisotropic features of shale micro-/meso-structures are related to the directional-dependency of elastic and fluid transport properties: - Micro-/meso-structure (μm to cm scale) characterization by electron microscopy and X-ray tomography; - Estimation of elastic anisotropy parameters on a single specimen using elastic wave propagation (cm scale); - Estimation of the permeability tensor using the steady-state method on orthogonal specimens (cm scale); - Estimation of the low-frequency diffusivity tensor using NMR method on orthogonal specimens (<

  14. Adapting a theoretical framework for characterizing students' use of equations in physics problem solving

    NASA Astrophysics Data System (ADS)

    Rebello, Carina M.; Rebello, N. Sanjay

    2012-02-01

    Previous studies have focused on the resources that students activate and utilize while solving a given physics problem. However, few studies explore how students relate a given resource such as an equation, to various types of physics problems and contexts and how they ascertain the meaning and applicability of that resource. We explore how students view physics equations, derive meaning from those equations, and use those equations in physics problem solving. We adapt Dubinsky and McDonald's description of APOS (action-process-object-schema) theory of learning in mathematics, to construct a theoretical framework that describes how students interpret and use equations in physics in terms of actions, processes, objects, and schemas. This framework provides a lens for understanding how students construct their understanding of physics concepts and their relation to equations. We highlight how APOS theory can be operationalized to serve as a lens for studying the use of mathematics in physics problem solving.

  15. Persistence of phosphor glow in microchannel plate image intensifiers

    NASA Technical Reports Server (NTRS)

    Torr, M. R.

    1985-01-01

    Image intensifier tubes using microchannel plate amplification stages and phosphor output stages are being increasingly used in various detection applications. In this paper, measurements of the decay times of what are attributed to be the P20 phosphors in various image intensifiers are reported. It is found that the long tail on the decay curve of the phosphor following illumination can be a limitation for certain observations. In addition, the background level of phosphor glow (which is seen by the subsequent detection system as a light signal) continues to build with continuing illumination.

  16. Enzymatic hydrolysis and physical characterization of commercial celluloses and cellulose-based ion-exchange powdered mixed resins.

    PubMed

    Clarkin, S D; Clesceri, L S

    2002-12-01

    Commercial celluloses (BH20, Epicote, FC+) and their cellulose-containing powdered mixed resins (PMR) were evaluated using enzymatic and physical methods. Samples were hydrolyzed with purified Trichoderma viride cellulase extract and measured for released reducing sugar using the dinitrosalicylic acid method. Physical characterization was performed with gross specific surface areas (GSSA) and relative crystalline indices (RCI). In addition, FC+ was exposed to physical and chemical processing commonly encountered in spent PMR processing to determine potential effects on reducing sugar release in high intensity containers. Reducing sugar released from the celluloses by T. viride cellulase ranged from 135.37 to 244.48 mg day(-1); the celluloses were highly crystalline, ranging from 82.47 to 84.57%; and the GSSA medians for the celluloses ranged from 1,298.60 cm(2) g(-1) to 2,493.20 cm(2) g(-1). Most processing treatments on the FC+ reduced the amount of reducing sugar released and increased RCI. Cellulose hydrolysis rates did not show a strong correlation with the physical characterization. These results suggest that (1) celluloses and PMR can serve as abundant sources of bioavailable carbon in water treatment systems, and (2) the use of correlative physical characteristics to evaluate a cellulose-based commercial product may not accurately predict microbial activity; a complementary microbial test such as cellulose hydrolysis with cellulase may prove useful. PMID:12466892

  17. Enhanced luminescence in Mg2+ codoped CaTiO3:Eu3+ phosphor prepared by solid state reaction

    NASA Astrophysics Data System (ADS)

    Vandana, C. Sai; Rudramadevi, B. Hemalatha

    2016-05-01

    CaTiO3 phosphors doped with Eu3+ and codoped with Mg2+ were prepared by Solid State Reaction method. The powders were characterized by X-ray diffraction, SEM with EDS, Raman scattering, and photoluminescence spectroscopy. The Crystalline phase and vibrational modes of the phosphors were studied using XRD pattern and Raman Spectrum respectively. The morphological studies of the phosphor samples were carried out using SEM analysis. From PL spectra we have observed two prominent red emission peaks around at 595 nm (5D0→7F1), 619 nm (5D0→7F2) with the excitation of 399nm for Eu3+ doped CaTiO3 powders. The PL intensity of CaTiO3:Eu3+ phosphor is enhanced significantly on codoping with Mg2+. The observed enhanced emissions are due to energy transfer from Mg2+ to Eu3+, which is due to radiative recombination. Eu3+ doped phosphors are well known to be promising materials for electroluminescent devices, optical amplifiers, and lasers.

  18. Encapsulating MAl 2O 4:Eu 2+, Dy 3+ (M = Sr, Ca, Ba) phosphors with triethanolamine to enhance water resistance

    NASA Astrophysics Data System (ADS)

    Ji, Ping Ting; Chen, Xiang Ying; Wu, Ye Qin

    2011-12-01

    Traditional aluminates phosphors with persistent luminescence are chemically unstable to water or moisture. Thus, how to improve the water-resistance of these phosphors is becoming a key issue in their practical applications. In this work, a series of alkaline earth aluminate phosphors including MAl 2O 4:Eu 2+, Dy 3+ (M = Sr, Ca, Ba) have been prepared by a co-precipitation synthesis and postannealing approach, using 8-hydroxyquinoline and sodium oxalate as precipitants. The samples before and after encapsulation were well characterized by means of XRPD, FESEM, FT-IR, TGA-DTG and PL techniques as well as water resistance measurements. The precipitants involved can react with Al 3+ and Sr 2+ (or Ca 2+, Ba 2+) to form complex compounds in aqueous solution, which further convert into porous phosphors by postannealing method under reducing atmosphere. Next, triethanolamine encapsulation at room temperature was conducted onto their surfaces to improve the water resistance. The results reveal that the encapsulation of aluminate phosphors with triethanolamine can effectively enhance the water resistance, and minimally affect on persistent phosphorescence.

  19. Spectral downshifting from blue to near infer red region in Ce3+-Nd3+ co-doped YAG phosphor

    NASA Astrophysics Data System (ADS)

    Sawala, N. S.; Omanwar, S. K.

    2016-07-01

    The YAG phosphors co-doped with Ce3+-Nd3+ ions by varying concentration of Nd3+ ion from 1 mol% to 15 mol% were successfully synthesized by conventional solid state reaction method. The phosphors were characterized by powder X-ray powder diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied in near infra red (NIR) and ultra violet visible (UV-VIS) region. The synthesized phosphors can convert a blue region photon (453 nm) into photons of NIR region (1063 nm). The energy transfer (ET) process was studied by time decay curve and PL spectra. The theoretical value of energy transfer efficiency (ETE) was calculated from time decay luminescence measurement and the maximum efficiency approached up to 82.23%. Hence this phosphor could be prime candidate as a downshifting (DS) luminescent convertor (phosphor) in front of crystalline silicon solar cell (c-Si) panels to reduce thermalization loss in the solar cells.

  20. Preparation and luminescence properties of orange-red Ba3Y(PO4)3:Sm3+ phosphors

    NASA Astrophysics Data System (ADS)

    Xu, Qiguang; Xu, Denghui; Sun, Jiayue

    2015-04-01

    Ba3Y(PO4)3:Sm3+ phosphors were prepared by a high temperature solid-state reaction in air. X-ray diffraction (XRD), photoluminescence spectra and temperature-dependent emission spectra were utilized to characterize the structure and luminescence properties of the as-prepared phosphor. The results show that the phosphor can be efficiently excited by ultraviolet light and emit a satisfactory orange-red performance, nicely, fitting in well with the widely used UV LED chip. Under 403 nm excitation, the 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2, and 11/2) emissions of Sm3+ are obviously observed. The optimum doping concentration is 5 mol% and corresponding quenching behavior is ascribed to be electric dipole-dipole interaction according to Dexter's theory. The temperature dependent luminescence of Ba3Y(PO4)3:Sm3+ phosphor is also discussed, and the activation energy for thermal quenching is calculated as 0.34 eV. Furthermore, the chromaticity coordinates of Ba3Y(PO4)3:Sm3+ phosphor are calculated to be (0.5558, 0.4380) and the lifetime values of Ba3Y0.995(PO4)3:0.005Sm3+ was 2.45 ms.

  1. Crystal structure, thermally stability and photoluminescence properties of novel Sr10(PO4)6O:Eu2+ phosphors

    NASA Astrophysics Data System (ADS)

    Guo, Qingfeng; Liao, Libing; Mei, Lefu; Liu, Haikun

    2015-03-01

    A series of novel luminescent phosphors Sr10(PO4)6O:Eu2+ with apatite structure were synthesized via a high temperature solid-state reaction. The phase structure, photoluminescence (PL) properties, the PL thermal stability, as well as the fluorescence decay curves of the samples were investigated to characterize the resulting samples, and the selected Sr9.97(PO4)6O:0.03Eu2+ phosphor exhibits strong thermal quenching resistance, retaining the luminance of 88.73% at 150 °C. The quenching concentration of Eu2+ in Sr10(PO4)6O was about 0.03 attributing to the dipole-quadrupole interaction. The Sr10(PO4)6O:Eu2+ phosphor exhibited a broad-band blue emission at 439 nm upon excitation at 346 nm. The results indicate that Sr10(PO4)6O:Eu2+ phosphors have potential applications as near UV-convertible phosphors for white-light UV LEDs.

  2. Physical Characterization of Solid-Liquid Slurries at High Weight Fractions Using Optical and Ultrasonic Methods, Final Report

    SciTech Connect

    Burgess, Lloyd W.

    2009-09-17

    Remediation of highly radioactive waste is a major technical and programmatic challenge for the DOE. Rapid, on-line physical characterization of highly concentrated slurries is required for the safe and efficient remediation of 90 million gallons of high level radioactive waste (HLW), sodium bearing waste, and mixed waste. The research presented here, describes a collaborative effort between Pacific Northwest National Laboratory (PNNL) and the University of Washington to directly address the need for rapid on-line characterization of the physical properties of HLW slurries during all phases of the remediation process, from in-tank characterization of sediments to monitoring of the concentration, particle size, and degree of agglomeration and gelation of slurries during transport. Near-surface characterization of the slurry flow in the particle size range from nanometer to micrometer is examined using optical low coherence reflectometry. Volumetric characterization at depths in the slurry flow, up to several centimeters in the particle size range from the micrometer to millimeter, is realized by utilizing ultrasonic backscatter and diffuses fields. One of the strengths, the teaming up of significant talents in both experimental and theoretical optics (University of Washington) and in ultrasonics [Pacific Northwest National Laboratory (PNNL)] provides a synergistic approach to integrate these complimentary techniques. One of the benefits of this combined approach is the physical characterization of HLW over a concentration and particle size range that is broader than can be achieved with today’s technology. This will avoid a costly increase in waste stream volume due to excess dilution, and will lessen chance of plugging pipes that could shut down expensive processing lines.

  3. Electron Paramagnetic Resonance and Photoluminescence Studies of LaMgAl11O19:Mn2+ Green Phosphors

    NASA Astrophysics Data System (ADS)

    Singh, Vijay; Chakradhar, R. P. S.; Rao, J. L.; Dhoble, S. J.; Kim, S. H.

    2014-09-01

    Manganese-doped LaMgAl11O19 powder has been prepared by an easy combustion method. Powder x-ray diffraction and scanning electron microscopy have been used to characterize the as-prepared phosphor. The electron paramagnetic resonance (EPR) spectrum of LaMgAl11O19:Mn2+ phosphor exhibits six-line hyperfine structure centered at g ≈ 1.973. The number of spins participating in resonance (N) and the paramagnetic susceptibility (χ) for the resonance signal at g ≈ 1.973 have been calculated as a function of temperature. The photoluminescence spectrum exhibits green emission at 516 nm, which is attributed to 4T1 → 6A1 transition of Mn2+ ions. From EPR and luminescence studies, it is observed that Mn2+ ions occupy Mg2+ sites and Mn2+ ions are located at tetrahedral sites in the prepared phosphors.

  4. Blue emission of Eu2+ doped LaMgAl11O19 phosphor prepared by combustion synthesis method

    NASA Astrophysics Data System (ADS)

    Pathak, A. A.; Yadav, P. J.; Talewar, R. A.; Joshi, C. P.; Moharil, S. V.

    2016-05-01

    Blue-emitting phosphor LaMgAl11O19:Eu2+ has been synthesized successfully at 500 °C by one step combustion synthesis method. The as-synthesized materials were characterized by powder x-ray diffraction (XRD) and photoluminescence (PL) techniques. Upon 365 nm excitation, emission spectra of the LaMgAl11O19:Eu2+ phosphors show a blue band at 450 nm. The excitation spectra corresponding to 4f7-4f65d transition of Eu2+ cover the spectral range of 280-430 nm. The concentration quenching of Eu2+ in the LaMgAl11O19 host was determined to be 3 mol%. The CIE chromaticity of LAM: Eu2+ phosphors was compared with the commercial BAM.

  5. The influence of synthesis methods on the morpho - structural and luminescent characteristics of rare earth silicate phosphors

    SciTech Connect

    Muresan, L. E.; Cadis, A. I.; Perhaita, I.; Oprea, B. F.; Silipas, D. T.

    2013-11-13

    Cerium activated yttrium silicate (Y{sub 2}SiO{sub 5}:Ce) phosphors were prepared by two different wet-chemical synthesis routes namely: simultaneous addition of reagents (SimAd) and solution combustion (SC) using yttriumcerium nitrate and urea as starting materials. TEOS or SiO{sub 2} fume were used as Si sources. A comparative study regarding the morpho-structural and luminescent properties of Y{sub 2}SiO{sub 5}:Ce phosphors is presented. The influence of the silicon source, same as the firing temperature on the samples characteristics were discussed. TG-SDTA, FT-IR, SEM, XRD and photoluminescence investigations were used to characterize the precursors and the corresponding phosphors.

  6. Synthesis and photoluminescence properties of Pb2+ doped inorganic borate phosphor NaSr4(BO3)3

    NASA Astrophysics Data System (ADS)

    Chauhan, A. O.; Koparkar, K. A.; Bajaj, N. S.; Omanwar, S. K.

    2016-05-01

    A series of Inorganic borate phosphors NaSr4(BO3)3 doped with Pb2+ was successfully synthesized by modified solid state diffusion method. The crystal structure and the phase purity of sample were characterized by powder X-ray diffraction (XRD). The photoluminescence properties of synthesized materials were investigated using spectrofluorometer at room temperature. The phosphor show strong broad band emission spectra in UVA region maximum at 370 nm under the excitation of 289 nm. The dependence of the emission intensity on the Pb2+ concentration for the NaSr4(BO3)3 were studied in details. The concentration quenching of Pb2+ doped NaSr4(BO3)3 was observed at 0.02 mol. The Stokes shifts of NaSr4(BO3)3: Pb2+ phosphor was calculated to be 7574 cm-1.

  7. Coherent tools for physics-based simulation and characterization of noise in semiconductor devices oriented to nonlinear microwave circuit CAD

    NASA Astrophysics Data System (ADS)

    Riah, Zoheir; Sommet, Raphael; Nallatamby, Jean C.; Prigent, Michel; Obregon, Juan

    2004-05-01

    We present in this paper a set of coherent tools for noise characterization and physics-based analysis of noise in semiconductor devices. This noise toolbox relies on a low frequency noise measurement setup with special high current capabilities thanks to an accurate and original calibration. It relies also on a simulation tool based on the drift diffusion equations and the linear perturbation theory, associated with the Green's function technique. This physics-based noise simulator has been implemented successfully in the Scilab environment and is specifically dedicated to HBTs. Some results are given and compared to those existing in the literature.

  8. Fine particle Sr{sub 2}SiO{sub 4}:Tb phosphor for the plasma display panel prepared by a combined approach

    SciTech Connect

    Yang, HongMei; School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 ; Gong, MengLian; Liang, Hongbin

    2010-07-15

    Sol-gel with microwave heating was employed to prepare fine particles Sr{sub 2}SiO{sub 4}:Tb phosphor. X-ray diffractometer was used to characterize the structural of the samples. The Scanning Electron Microscope image shows that the particle size is about 300 nm. The phosphor particles have several advantages in the morphology, such as excellent surface quality, spherical shape, and narrow size distribution with no aggregation. The VUV luminescence measurements indicate that the phosphor presents an intense excitation band at 173 nm. Because the wavelength of excitation source in PDP is mainly at 147 and 172 nm, it makes Sr{sub 2}SiO{sub 4}:Tb a potential candidate for green emitting phosphor for plasma display panel (PDP) application. Photoluminescence (PL) measurements indicate that the Sr{sub 2}SiO{sub 4}:Tb particles present excellent green emission at 542 and 547 nm excitated at 236 and 172 nm, respectively.

  9. Fluid flow and reaction fronts: characterization of physical processes at the microscale using SEM analyses

    NASA Astrophysics Data System (ADS)

    Beaudoin, Nicolas; Koehn, Daniel; Toussaint, Renaud; Gomez-Rivas, Enrique; Bons, Paul; Chung, Peter; Martín-Martín, Juan Diego

    2014-05-01

    Fluid migrations are the principal agent for mineral replacement in the upper crust, leading to dramatic changes in the porosity and permeability of rocks over several kilometers. Consequently, a better understanding of the physical parameters leading to mineral replacement is required to better understand and model fluid flow and rock reservoir properties. Large-scale dolostone bodies are one of the best and most debated examples of such fluid-related mineral replacement. These formations received a lot of attention lately, and although genetic mechanics and implications for fluid volume are understood, the mechanisms controlling the formation and propagation of the dolomitization reaction front remain unclear. This contribution aims at an improvement of the knowledge about how this replacement front propagates over space and time. We study the front sharpness on hand specimen and thin section scale and what the influence of advection versus diffusion of material is on the front development. In addition, we demonstrate how preexisting heterogeneities in the host rock affect the propagation of the reaction front. The rock is normally not homogeneous but contains grain boundaries, fractures and stylolites, and such structures are important on the scale of the front width. Using Scanning Electron Microscopy and Raman Spectroscopy we characterized the reaction front chemistry and morphology in different context. Specimens of dolomitization fronts, collected from carbonate sequences of the southern Maestrat Basin, Spain and the Southwestern Scottish Highlands suggest that the front thickness is about several mm being relatively sharp. Fluid infiltrated grain boundaries and fractures forming mm-scale transition zone. We study the structure of the reaction zone in detail and discuss implications for fluid diffusion-advection models and mineral replacement. In addition we formulate a numerical model taking into account fluid flow, diffusion and advection of the mobile

  10. Holocene paleoclimate characterization in Lago Fagnano (Tierra del Fuego) using sedimentary, physical and geochemical proxies

    NASA Astrophysics Data System (ADS)

    Vizcaino Marti, A.; Dunbar, R. B.; Wahl, D.; Moy, C. M.; Mucciarone, D. A.; Anderson, L.; Guilderson, T. P.

    2010-12-01

    Tierra del Fuego is the world's southernmost landmass outside of Antarctica. Two features of ocean circulation control the climate of Tierra del Fuego: the Southern Ocean circumpolar flow and the South Pacific Gyre. Together with Patagonia, Tierra del Fuego is the only terrestrial region directly influenced by the southern hemisphere westerly winds. This region is also a tectonically active area affected by volcanic and seismic activity related to South American and Scotia-Antarctic plate boundaries. Accommodated along the Magallanes-Fagnano fault system, as part of the plate boundary, the Lago Fagnano is the largest lake in Tierra del Fuego. This E-W trending lake is 100 km long and 5-15 km wide. Our investigations were carried out on the upper 4 meters of an 8.4 m long piston core obtained at 69 m water depth in Bahía Grande (LF06-PC8); a southwestern lake sub-basin separated from the main lake by a shallow sill. Our studies are based on the integration of sediment description, physical properties, pollen, and geochemical analyses including C and N isotopes (1cm interval) and XRF scan (1mm interval). The age model for the core is based on radiocarbon ages and tephrochronology. Additionally, a 800 km long grid of high resolution seismic profiles support the sedimentary analyses and allow the correlation with other cores from within the lake basin. LF06-PC8 yields continuous and high accumulation-rate sedimentary sections for Lago Fagnano. The presented sediment record corresponds to a laminated hemipelagite with presence of a single but complex mass transport deposit interval. An accurate sedimentological interpretation of the core together with the radiocarbon ages and tephra dates allow to identify and characterize the main sedimentary processes occurring in the lake over the last 8 kyr. In addition, proxy data (C and N isotopes and XRF scan data) from the laminated hemipelagic interval provide a reliable record of past variability in the westerly wind field as

  11. Geant4 simulation of the response of phosphor screens for X-ray imaging

    NASA Astrophysics Data System (ADS)

    Pistrui-Maximean, S. A.; Freud, N.; Létang, J. M.; Koch, A.; Munier, B.; Walenta, A. H.; Montarou, G.; Babot, D.

    2006-07-01

    In order to predict and optimize the response of phosphor screens, it is important to understand the role played by the different physical processes inside the scintillator layer. A simulation model based on the Monte Carlo code Geant4 was developed to determine the Modulation Transfer Function (MTF) of phosphor screens for energies used in X-ray medical imaging and nondestructive testing applications. The visualization of the dose distribution inside the phosphor layer gives an insight into how the MTF is progressively degraded by X-ray and electron transport. The simulation model allows to study the influence of physical and technological parameters on the detector performances, as well as to design and optimize new detector configurations. Preliminary MTF measurements have been carried out and agreement with experimental data has been found in the case of a commercial screen (Kodak Lanex Fine) at an X-ray tube potential of 100 kV. Further validation with other screens (transparent or granular) at different energies is under way.

  12. Studies concerning the properties of some europium activated phosphors based on yttrium tantalate

    NASA Astrophysics Data System (ADS)

    Popovici, Elisabeth-Jeanne; Nazarov, Mihail; Muresan, Laura; Noh, Do Young; Bica, Ecaterina; Morar, Marius; Arellano, Ivan; Indrea, Emil

    2009-08-01

    Rare earth activated Y TaO4 based phosphors are perspective materials for optoelectronics. The paper presents some physical and chemical aspects related to the influence of the host lattice composition and crystalline order on the luminescence of rare earth ions. In this respect, Eu-activated Y (Ta,Nb)O4 powders have been prepared by solid state reaction, from homogeneous mixtures consisting of oxide precursors and flux. Photoluminescence (PL) spectroscopy, X-ray diffraction, FTIR spectroscopy and SEM have been used to investigate the structural and luminescent properties of Y (Ta,Nb)O4:Eu phosphors. Attempts has been made at establishing a correlation between the morphostructural parameters of the host lattice containing variable niobium amount and the PL properties. The interaction between the tantalate-niobate matrix and the Eu-emission centres is considered in correlation with the PL characteristics.

  13. Characterizing Pedagogical Practices of University Physics Students in Informal Learning Environments

    ERIC Educational Resources Information Center

    Hinko, Kathleen A.; Madigan, Peter; Miller, Eric; Finkelstein, Noah D.

    2016-01-01

    University educators (UEs) have a long history of teaching physics not only in formal classroom settings but also in informal outreach environments. The pedagogical practices of UEs in informal physics teaching have not been widely studied, and they may provide insight into formal practices and preparation. We investigate the interactions between…

  14. Soil Physical Characterization of Soil under Long-Term Tillage and Manure Application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil physical properties play an intergral role in maintaining soil quality for sustainable agricultural practices. Agronomic practices such as tillage systems and organic amendments have been shown to influence soil physical properties. A study was conducted to evaluate effects of long-term manure ...

  15. Synthesis and luminescent properties of spindle-like CaWO{sub 4}:Sm{sup 3+} phosphors

    SciTech Connect

    Tian, Yue; Liu, Yu; Hua, Ruinian; Na, Liyan; Chen, Baojiu

    2012-01-15

    Graphical abstract: In this paper, spindle-like CaWO{sub 4}:Sm{sup 3+} phosphors were prepared via a polyvinylpyrrolidone (PVP)-assisted sonochemical process. Dependence of emission intensity on Sm{sup 3+} ions concentration in the CaWO{sub 4}:Sm{sup 3+} phosphor were also calculated via a nonlinear fitting by using the formula y = ax/(1 + bx{sup c}). Highlights: Black-Right-Pointing-Pointer The samples were prepared via a PVP assisted sonochemical process. Black-Right-Pointing-Pointer The color coordinates for 1 mol% Sm{sup 3+} doped CaWO{sub 4} phosphor were calculated. Black-Right-Pointing-Pointer The D-D interaction is responsible for concentration quenching between Sm{sup 3+} ions. Black-Right-Pointing-Pointer The critical energy transfer distances (R{sub c}) were obtained. -- Abstract: Spindle-like CaWO{sub 4}:Sm{sup 3+} phosphors were prepared via a Polyvinylpyrrolidone (PVP)-assisted sonochemical process, and characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and photoluminescence spectroscopy (PL). The XRD results suggested that the prepared samples are single-phase. The FE-SEM images indicated that the prepared CaWO{sub 4}:Sm{sup 3+} phosphors are composed of many spindles with maximum average diameter of 150 nm and maximum average length of 500 nm. Under 404 nm excitation, the characteristic emissions corresponding to {sup 4}G{sub 5/2} {yields} {sup 6}H{sub J} (J = 5/2, 7/2, 9/2 and 11/2) transitions of Sm{sup 3+} in CaWO{sub 4} phosphors were observed. The color coordinates for 1 mol% Sm{sup 3+} doped CaWO{sub 4} phosphor were calculated to be (0.595, 0.404). The fluorescent concentration quenching of Sm{sup 3+} doped spindle-like phosphors was studied based on the Van Uitert's model, and it was found that the electric dipole-dipole (D-D) interaction is the dominant energy transfer mechanism between Sm{sup 3+} ions in the CaWO{sub 4}:Sm{sup 3+} phosphors. The critical energy transfer distance was

  16. Making red emitting phosphors with Pr 3+

    NASA Astrophysics Data System (ADS)

    Boutinaud, Philippe; Pinel, Eric; Oubaha, Mohamed; Mahiou, Rachid; Cavalli, Enrico; Bettinelli, Marco

    2006-01-01

    UV-excited red-emitting phosphors are obtained using Pr 3+ as the luminescent activator and host lattices containing closed-shell transition metal ions (especially titanates, vanadates and niobates). In these oxidant lattices, the quenching of the otherwise greenish-blue emitting 3P 0 level is induced by a low-lying Pr-to-metal intervalence charge transfer state (IVCT). A simple criterion based on the optical electronegativities of the d 0 lattice cations (M n+) and average Pr 3+ - M n+ distances is proposed to predict 3P 0 quenching in these lattices.

  17. Application of phosphor thermometry to galvanneal processing

    SciTech Connect

    Beshears, D.L.; Abston, R.A.; Allison, S.W.

    1997-05-08

    A system has been developed for determining temperatures of galvanneal steel during the production process. It is based on an optical method known as phosphor thermometry and it provides for reliable, emissivity-independent measurements. This development is a part of the American Iron and Steel Institute`s (AISI) Advanced Process Control Program, a joint endeavor between the AISI and the U.S. Department of Energy. Galvanneal is a corrosion-resistant steel that is widely used for automotive and other applications. Improved thermometry should enable steelmakers to significantly improve product quality as well as to increase the yield. ultimately decreasing costs.

  18. Preparation and evaluation of advanced catalysts for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Stonehart, P.; Baris, J.; Hockmuth, J.; Pagliaro, P.

    1984-01-01

    The platinum electrocatalysts were characterized for their crystallite sizes and the degree of dispersion on the carbon supports. One application of these electrocatalysts was for anodic oxidation of hydrogen in hot phosphoric acid fuel cells, coupled with the influence of low concentrations of carbon monoxide in the fuel gas stream. In a similar way, these platinum on carbon electrocatalysts were evaluated for oxygen reduction in hot phosphoric acid. Binary noble metal alloys were prepared for anodic oxidation of hydrogen and noble metal-refractory metal mixtures were prepared for oxygen reduction. An exemplar alloy of platinum and palladium (50/50 atom %) was discovered for anodic oxidation of hydrogen in the presence of carbon monoxide, and patent disclosures were submitted. For the cathode, platinum-vanadium alloys were prepared showing improved performance over pure platinum. Preliminary experiments on electrocatalyst utilization in electrode structures showed low utilization of the noble metal when the electrocatalyst loading exceeded one weight percent on the carbon.

  19. Development of europium doped BaSO4 TL OSL dual phosphor for radiation dosimetry applications

    NASA Astrophysics Data System (ADS)

    Patle, Anita; Patil, R. R.; Kulkarni, M. S.; Bhatt, B. C.; Moharil, S. V.

    2015-08-01

    This paper presents the results on the preparation and characterization of Europium-doped Barium sulfate (BaSO4: Eu) TL /OSL dual phosphor. The OSL sensitivity was found to be 11% of the commercially available Al2O3: C, using area integration method. The sample also shows good TL sensitivity and the dosimetric peak appears around 190°C with a shoulder at 282°C. After OSL readout, No change in the TL glow curve is observed. Since the observed TL peaks are not responsible for the observed OSL, good OSL as well as TL sensitivity and low fading will make this phosphor suitable for applications in radiation dosimetry using OSL as well as TL.

  20. Rapid thermal annealing of spin-coated phosphoric acid films for shallow junction formation

    NASA Astrophysics Data System (ADS)

    Sivoththaman, S.; Laureys, W.; Nijs, J.; Mertens, R.

    1997-07-01

    Rapid thermal annealing (RTA) of spin-coated phosphoric acid (H3PO4) films on silicon substrates has been studied for the formation of shallow junctions. The junctions are characterized by spreading resistance profiling. Device quality, shallow (<0.2 μm), n+p junctions are formed by the resulting phosphorous diffusion with the junction depth and surface concentration depending on the RTA conditions. The films have been studied by Fourier transform infrared spectroscopy after various RTA treatments. The presence of P=O bonds in the films becomes evident after the RTA treatment at elevated temperatures (>750 °C), below which absorption bands originating from water species are noted. More than 15% efficient, shallow emitter, large-area (10 cm×10 cm) n+pp+ silicon solar cells are fabricated with a short-time processing using this rapid thermal processing technique.

  1. Method for incorporating radioactive phosphoric acid solutions in concrete

    DOEpatents

    Wolf, Gary A [Kennewick, WA; Smith, Jeffrey W [Lancaster, OH; Ihle, Nathan C [Walla Walla, WA

    1984-01-01

    A method for incorporating radioactive phosphoric acid solutions in concrete is described wherein the phosphoric acid is reacted with Ca(OH).sub.2 to form a precipitate of hydroxyapatite and the hydroxyapatite is mixed with portland cement to form concrete.

  2. Method for incorporating radioactive phosphoric acid solutions in concrete

    DOEpatents

    Wolf, G.A.; Smith, J.W.; Ihle, N.C.

    1982-07-08

    A method for incorporating radioactive phosphoric acid solutions in concrete is described wherein the phosphoric acid is reacted with Ca(OH)/sub 2/ to form a precipitate of hydroxyapatite and the hydroxyapatite is mixed with Portland cement to form concrete.

  3. Phosphor Scanner For Imaging X-Ray Diffraction

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C.; Hecht, Diana L.; Witherow, William K.

    1992-01-01

    Improved optoelectronic scanning apparatus generates digitized image of x-ray image recorded in phosphor. Scanning fiber-optic probe supplies laser light stimulating luminescence in areas of phosphor exposed to x rays. Luminescence passes through probe and fiber to integrating sphere and photomultiplier. Sensitivity and resolution exceed previously available scanners. Intended for use in x-ray crystallography, medical radiography, and molecular biology.

  4. World wide IFC phosphoric acid fuel cell implementation

    SciTech Connect

    King, J.M. Jr

    1996-04-01

    International Fuel Cells, a subsidary of United technologies Corporation, is engaged in research and development of all types of fuel cell technologies and currently manufactures alkaline fuel cell power plants for the U.S. manned space flight program and natural gas fueled stationary power plants using phosphoric acid fuel cells. This paper describes the phosphoric acid fuel cell power plants.

  5. Physical interpretation and development of ultrasonic nondestructive evaluation techniques applied to the quantitative characterization of textile composite materials

    NASA Technical Reports Server (NTRS)

    Miller, James G.

    1993-01-01

    In this Progress Report, we describe our current research activities concerning the development and implementation of advanced ultrasonic nondestructive evaluation methods applied to the characterization of stitched composite materials and bonded aluminum plate specimens. One purpose of this investigation is to identify and characterize specific features of polar backscatter interrogation which enhance the ability of ultrasound to detect flaws in a stitched composite laminate. Another focus is to explore the feasibility of implementing medical linear array imaging technology as a viable ultrasonic-based nondestructive evaluation method to inspect and characterize bonded aluminum lap joints. As an approach to implementing quantitative ultrasonic inspection methods to both of these materials, we focus on the physics that underlies the detection of flaws in such materials.

  6. Synthesis and characterization of Eu{sup 3+}-doped CaZrO{sub 3}-based perovskite-type phosphors. Part I: Determination of the Eu{sup 3+} occupied site using the ALCHEMI technique

    SciTech Connect

    Sakaida, Satoshi; Shimokawa, Yohei; Asaka, Toru; Honda, Sawao; Iwamoto, Yuji

    2015-07-15

    Highlights: • Eu{sup 3+}-doped CaZrO{sub 3}-based compounds were synthesized by the solid state reaction. • PL emission intensity at 614 nm was changed by the second dopant cations. • The site substituted by Eu{sup 3+} cations was investigated by using XRD and ALCHEMI technique. • The dominant Eu{sup 3+} substitution site was found as the B site (Zr{sup 4+}) in the CaZrO{sub {sup 3}}. • The dominant Eu{sup 3+} substitution site could be strongly influenced by the co-dopants. - Abstract: Eu{sup 3+}-doped CaZrO{sub 3}, SrZrO{sub 3}, and Mg{sup 2+}- or Sr{sup 2+}-co-doped CaZrO{sub 3} were synthesized by conventional solid state reaction and their photoluminescence (PL) properties were characterized. The Eu{sup 3+}-doped CaZrO{sub 3}-based compounds exhibited characteristic emissions of Eu{sup 3+} (f–f transition). The intensity of the main PL emission peak at 614 nm increased with Mg{sup 2+} co-doping, while it decreased with the amount of co-doped Sr{sup 2+}. The site substituted by Eu{sup 3+} cations in the CaZrO{sub 3}-based compounds was investigated by X-ray diffraction analysis and energy-dispersive X-ray analysis based on the electron channeling effects in transmission electron microscopy. The Eu{sup 3+} cations were determined to occupy mainly the B site (Zr{sup 4+}) in CaZrO{sub 3}. The dominant Eu{sup 3+} substitution site was also strongly influenced by the co-dopant, and the ionic radius of the co-dopant was identified as an important factor that determines the dominant Eu{sup 3+} substitution site.

  7. Enhancement of Luminous Efficacy by Random Patterning of Phosphor Matrix

    NASA Astrophysics Data System (ADS)

    Fellows, Natalie; Masul, Hisashi; Diana, Frederic; Denbaars, Steven P.; Nakamura, Shuji

    We have demonstrated the ability to increase the luminous flux and luminous efficacy of white light-emitting diodes (LEDs) by randomly patterning the surface of the yellow phosphor matrix. The phosphor was moved away from the LED die by placing it on top of a silicone optic and then roughening the surface of the phosphor/resin mixture. It was found that the roughening increases the luminous flux and efficacy by 10% over the smooth, non-patterned phosphor mixture. The roughened sample’s operating voltage, luminous flux, luminous efficacy, CCT, color coordinates, and CRI were 3.2 V, 7.4 lm, 115.6 lm/W, 4244 K, (0.388, 0.448), and 61 at 20 mA, CW, and room temperature operation. A brief presentation on phosphor scattering is introduced to help explain the effect of the roughening.

  8. Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

    NASA Technical Reports Server (NTRS)

    Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

    2009-01-01

    Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

  9. Fluxgate magnetorelaxometry for characterization of hydrogel polymerization kinetics and physical entrapment capacity.

    PubMed

    Heim, E; Harling, S; Ludwig, F; Menzel, H; Schilling, M

    2008-05-21

    Hydrogels have the potential for providing drug delivery systems with long release rates. The polymerization kinetics and the physical entrapment capacity of photo-cross-linked hydroxyethyl methacrylate hydroxyethylstarch hydrogels are investigated with a non-destructive method. For this purpose, superparamagnetic nanoparticles as replacements for biomolecules are used as probes. By analyzing their magnetic relaxation behavior, the amounts of physically entrapped and mobile nanoparticles can be determined. The hydrogels were loaded with five different concentrations of nanoparticles. Different methods of analysis of the relaxation curves and the influence of the microviscosity are discussed. This investigation allows one to optimize the UV light irradiation time and to determine the amount of physically entrapped nanoparticles in the hydrogel network. It was found that the polymerization kinetics is faster for decreasing nanoparticle concentration but not all nanoparticles can be physically entrapped in the network. PMID:21694236

  10. Advanced Analytical/Physics Tools to Characterize Tire Materials and Behavior

    NASA Astrophysics Data System (ADS)

    Gerspacher, Michel

    2001-10-01

    Tires are assembled with common materials like polymers, fillers, reinforcing fibers and various chemicals which are used to cure the rubber compound, and also, to protect the finished tire from oxydative degradation. This is certainly more related to chemistry than to physics. Nevertheless, a finished tire on the road is becoming a fascinating object of physics if one wants to understand its behavior. Indeed, it is its viscoelastic nature which confers to the tire its unique capabilities. The lecture will be centered on the usage of physical methods, not only to study the visco- elasticity of the composite, but also the nature of the interactions between the materials composing the tires. It will be shown that the usage of physics has tremendously helped to better understand the tire and also participated in developing new generations of tires.

  11. Self-activating and doped tantalate phosphors.

    SciTech Connect

    Nyman, May Devan; Rohwer, Lauren Elizabeth Shea

    2011-01-01

    An ideal red phosphor for blue LEDs is one of the biggest challenges for the solid-state lighting industry. The appropriate phosphor material should have good adsorption and emission properties, good thermal and chemical stability, minimal thermal quenching, high quantum yield, and is preferably inexpensive and easy to fabricate. Tantalates possess many of these criteria, and lithium lanthanum tantalate materials warrant thorough investigation. In this study, we investigated red luminescence of two lithium lanthanum tantalates via three mechanisms: (1) Eu-doping, (2) Mn-doping and (3) self-activation of the tantalum polyhedra. Of these three mechanisms, Mn-doping proved to be the most promising. These materials exhibit two very broad adsorption peaks; one in the UV and one in the blue region of the spectrum; both can be exploited in LED applications. Furthermore, Mn-doping can be accomplished in two ways; ion-exchange and direct solid-state synthesis. One of the two lithium lanthanum tantalate phases investigated proved to be a superior host for Mn-luminescence, suggesting the crystal chemistry of the host lattice is important.

  12. Aminophenyl double decker silsesquioxanes: Spectroscopic elucidation, physical and thermal characterization, and their applications

    NASA Astrophysics Data System (ADS)

    Schoen, Beth Whitney

    The incorporation of cage-like silsesquioxanes (SQ) to form polymers has demonstrated property enhancements in areas such as: thermal and mechanical characteristics, flame retardance, dielectric properties, and oxidative resistance. However, with most hybrid polymers investigated, the attached SQs are pendant with respect to the polymer backbone. A recently developed class of these nano-structured, cage-like silsesquioxanes, formally known as double decker silsesquioxanes (DDSQ), offers the opportunity to form hybrid polymers with SQ cages as a part of the polymer backbone. However, during the capping reaction, these functionalized DDSQs generate cis and trans isomers with respect to the 3D Si-O core. Therefore, it is logical to characterize properties, which will allow for optimization of capping reaction parameters, particularly if one isomer is favored over the other. Moreover, these characteristics are also relevant when reacting or incorporating these isomers, or mixtures thereof, with other molecules to form novel materials. In this dissertation, three aminophenyl DDSQs were synthesized. More specifically, two meta- aminophenyl DDSQs, which were differentiated according to the moiety attached to the D-Si (methyl or cyclohexyl), and one para-aminophenyl DDSQ with a methyl moiety were used. Chemical, physical, and thermal characteristics were evaluated for individual isomers as well as binary mixtures of different cis/trans ratios. The 1H NMR spectra of the cis and trans isomers of these DDSQ had not previously been assigned to a degree that allowed for quantification, which was necessary for these studies. Thus, 1H-29Si HMBC correlations were applied to facilitate 1H spectral assignments and also to confirm previous 29Si assignments. Using 1H NMR not only saves time and material over 29Si NMR, but also provides a more accurate quantification, thus allowing for the ratio of cis and trans isomers present in each compound to be determined. Solubility behavior was

  13. Preparation, luminescence and defect studies of Eu{sup 2+}-activated strontium hexa-aluminate phosphor prepared via combustion method

    SciTech Connect

    Singh, Vijay; Gundu Rao, T.K.; Zhu Junjie . E-mail: jjzhu@nju.edu.cn

    2006-08-15

    Preparation of Eu{sup 2+} ions activated strontium hexa-aluminate phosphor using the combustion method is described. An efficient phosphor can be prepared by this method at reaction temperatures as low as 500 deg. C in a few minutes. Powder X-ray diffraction (XRD), transmission electron microscopy, scanning electron microscope analysis were used to characterize the as prepared product and the optical properties were studied by photoluminescence (PL) spectra. Thermally stimulated luminescence studies also have been carried out on SrAl{sub 12}O{sub 19}:Eu{sup 2+} phosphor. The TSL glow curve is broad and indicates two dominant peaks at 206 and 345 deg. C. Defect centres formed in irradiated phosphor have been studied using the technique of electron spin resonance. One of the centres is characterized by an isotropic g-value of 2.0055 and is assigned to a F{sup +} centre. The two annealing stages of F{sup +} centre in the region 125-230 and 340-390 deg. C appear to correlate with the release of carriers resulting in TSL peaks at 206 and 345 deg. C, respectively. - Graphical abstract: SEM image of SrAl{sub 12}O{sub 19}:Eu.

  14. Emerging cool white light emission from Dy(3+) doped single phase alkaline earth niobate phosphors for indoor lighting applications.

    PubMed

    Vishwakarma, Amit K; Jha, Kaushal; Jayasimhadri, M; Sivaiah, B; Gahtori, Bhasker; Haranath, D

    2015-10-21

    Single-phase cool white-light emitting BaNb2O6:Dy(3+) phosphors have been synthesized via a conventional solid-state reaction method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) observations and spectrofluorophotometric measurements. XRD and Rietveld structural refinement studies confirm that all the samples exhibit pure orthorhombic structure [space group -C2221(20)]. SEM observations reveal the dense particle packaging with irregular morphology in a micron range. The as-prepared phosphors exhibit blue (482 nm) and yellow (574 nm) emissions under 349, 364, 386 and 399 nm excitations corresponding to (4)F9/2→(6)HJ (J = 15/2, 13/2) transitions of Dy(3+) ions. The energy transfer mechanism between Dy(3+) ions has been studied in detail and the luminescence decay lifetime for the (4)F9/2 level was found to be around 146.07 μs for the optimized phosphor composition. The calculated Commission Internationale de L'Eclairage (CIE) chromaticity coordinates for the optimized phosphor are (x = 0.322, y = 0.339), which are close to the National Television Standard Committee (NTSC) (x = 0.310, y = 0.316) coordinates. The values of CIE chromaticity coordinates and correlated color temperature (CCT) of 5907 K endorse cool white-light emission from the phosphor. The study reveals that BaNb2O6:Dy(3+) phosphor could be a potential candidate for near ultra-violet (NUV) excited white-LED applications. PMID:26374377

  15. Fire severity effects on ash extractable Total Phosphorous

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Úbeda, Xavier; Martin, Deborah

    2010-05-01

    Phosphorous (P) is a crucial element to plant nutrition and limits vegetal production. The amounts of P in soil are lower and great part of this nutrient is absorbed or precipitated. It is well known that fire has important implications on P cycle, that can be lost throughout volatilization, evacuated with the smoke, but also more available to transport after organic matter mineralization imposed by the fire. The release of P depends on ash pH and their chemical and physical characteristics. Fire temperatures impose different severities, according to the specie affected and contact time. Fire severity is often evaluated by ash colour and this is a low-cost and excellent methodology to assess the fire effects on ecosystems. The aim of this work is study the ash properties physical and chemical properties on ash extractable Total Phosphorous (TP), collected in three wildfires, occured in Portugal, (named, (1) Quinta do Conde, (2) Quinta da Areia and (3) Casal do Sapo) composed mainly by Quercus suber and Pinus pinaster trees. The ash colour was assessed using the Munsell color chart. From all three plots we analyzed a total of 102 ash samples and we identified 5 different ash colours, ordered in an increasing order of severity, Very Dark Brown, Black, Dark Grey, Very Dark Grey and Light Grey. In order to observe significant differences between extractable TP and ash colours, we applied an ANOVA One Way test, and considered the differences significant at a p<0.05. The results showed that significant differences in the extractable TP among the different ash colours. Hence, to identify specific differences between each ash colour, we applied a post-hoc Fisher LSD test, significant at a p<0.05. The results obtained showed significant differences between the extractable TP from Very dark Brown and Black ash, produced at lower severities, in relation to Dark Grey, Very Dark Grey and Light Grey ash, generated at higher severities. The means of the first group were higher

  16. [Removal and Recycle of Phosphor from Water Using Magnetic Core/Shell Structured Fe₃O₄ @ SiO₂Nanoparticles Functionalized with Hydrous Aluminum Oxide].

    PubMed

    Lai, Li; Xie, Qiang; Fang, Wen-kan; Xing, Ming-chao; Wu, De-yi

    2016-04-15

    A novel magnetic core/shell structured nano-particle Fe₃O₄@ SiO₂phosphor-removal ahsorbent functionalized with hydrous aluminum oxides (Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O) was synthesized. Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O was characterized by XRD, TEM, VSM and BET nitrogen adsorption experiment. The XRD and TEM results demonstrated the presence of the core/shell structure, with saturated magnetization and specific surface area of 56.00 emu · g⁻¹ and 47.27 m² · g⁻¹, respectively. In batch phosphor adsorption experiment, the Langmuir adsorption maximum capacity was 12.90 mg · g⁻¹ and nearly 96% phosphor could be rapidly removed within a contact time of 40 mm. Adsorption of phosphor on Fe₃O₄@ SiO₂@ Al₂O₃ · nH₂O was highly dependent on pH condition, and the favored pH range was 5-9 in which the phosphor removal rate was above 90%. In the treatment of sewage water, the recommended dosage was 1.25 kg · t⁻¹. In 5 cycles of adsorption-regeneration-desorption experiment, over 90% of the adsorbed phosphor could be desorbed with 1 mol · L⁻¹ NaOH, and Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O could be reused after regeneration by pH adjustment with slightly decreased phosphor removal rate with increasing recycling number, which proved the recyclability of Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O and thereby its potential in recycling of phosphor resources. PMID:27548967

  17. Crystal structure and luminescence properties of a novel red-emitting phosphor BaAlBO{sub 3}F{sub 2}:Eu{sup 3+}

    SciTech Connect

    Chen, Wanping Zhou, Ahong; Liu, Yan; Dai, Xiaoyan; Yang, Xin

    2014-12-15

    A series of novel red-emitting phosphors BaAlBO{sub 3}F{sub 2}:xEu{sup 3+} (0.001≤x≤0.08) were first synthesized via a high temperature solid-state reaction. X-ray diffraction and photoluminescence spectroscopy were used to characterize the crystal structure and photoluminescence properties of the phosphor, respectively. The phosphor can be effectively excited with a 395 nm light, and shows a dominant {sup 5}D{sub 0}−{sup 7}F{sub 2} emission with chromatic coordination of 0.628 and 0.372. The optimal doping concentration is about 0.04. Rietveld refinement results and the luminescence behavior of Eu{sup 3+} indicate that the Eu{sup 3+} ion occupies a C{sub 3} symmetry site, and the host BaAlBO{sub 3}F{sub 2} has a hexagonal structure with P-6 space group. In addition, the phosphor could be a potential candidate as red-emitting phosphor for application in white light-emitting diode. - Graphical abstract: The luminescence behavior and Rietveld refinement of BaAlBO{sub 3}F{sub 2}:Eu{sup 3+} indicate that the red-emitting phosphor has potential application in white LED and the host has a hexagonal structure with P-6 space group. - Highlights: • A novel red-emitting phosphor BaAlBO{sub 3}F{sub 2}:Eu{sup 3+} is first synthesized. • The crystal structure of BaAlBO{sub 3}F{sub 2} is confirmed. • The phosphor shows potential application in white LED.

  18. Photoluminescence and cathodoluminescence properties of Eu{sup 3+} ions activated AMoO{sub 4} (A = Mg, Ca, Sr, Ba) phosphors

    SciTech Connect

    Du, Peng; Yu, Jae Su

    2015-10-15

    Highlights: • Under 393 nm excitation, strong red emission located at 615 nm was observed in all the samples. • The Eu{sup 3+}-activated CaMoO{sub 4} phosphor exhibited the strongest PL properties. • The CIE chromaticity coordinate of Eu{sup 3+}-activated CaMoO{sub 4} phosphor was (0.647,0.352). • The color purity of Eu{sup 3+}-activated CaMoO{sub 4} phosphor was 92.8%. • Strong CL properties were observed in the Eu{sup 3+}-activated CaMoO{sub 4} phosphor. - Abstract: Eu{sup 3+}-activated AMoO{sub 4} (A = Mg, Ca, Sr, Ba) phosphors were synthesized by a solid-state reaction method. Photoluminescence and cathodoluminescence (CL) spectra as well as X-ray diffraction patterns were measured to characterize the fabricated samples. Under 393 nm excitation, strong red emissions located at ∼615 nm corresponding to the {sup 5}D{sub 0} → {sup 7}F{sub 2} transition of Eu{sup 3+} ions were observed in all the samples. Compared with other Eu{sup 3+} ions activated AMoO{sub 4} (A = Mg, Sr, Ba) phosphors, Eu{sup 3+}-activated CaMoO{sub 4} phosphor exhibited the strongest red emission intensity with better Commission Internationale de L’Eclairage chromaticity coordinate and higher color purity. Furthermore, the CL results indicated that the Eu{sup 3+}-activated CaMoO{sub 4} phosphor had excellent luminescence properties.

  19. Crystal structure, thermally stability and photoluminescence properties of novel Sr{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+} phosphors

    SciTech Connect

    Guo, Qingfeng; Liao, Libing Mei, Lefu; Liu, Haikun

    2015-03-15

    A series of novel luminescent phosphors Sr{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+} with apatite structure were synthesized via a high temperature solid-state reaction. The phase structure, photoluminescence (PL) properties, the PL thermal stability, as well as the fluorescence decay curves of the samples were investigated to characterize the resulting samples, and the selected Sr{sub 9.97}(PO{sub 4}){sub 6}O:0.03Eu{sup 2+} phosphor exhibits strong thermal quenching resistance, retaining the luminance of 88.73% at 150 °C. The quenching concentration of Eu{sup 2+} in Sr{sub 10}(PO{sub 4}){sub 6}O was about 0.03 attributing to the dipole–quadrupole interaction. The Sr{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+} phosphor exhibited a broad-band blue emission at 439 nm upon excitation at 346 nm. The results indicate that Sr{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+} phosphors have potential applications as near UV-convertible phosphors for white-light UV LEDs. - Graphical abstract: Sr{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+} phosphors have potential applications as near UV-convertible phosphors for white-light UV LEDs. - Highlights: • Sr{sub 9.97}(PO{sub 4}){sub 6}O:0.03Eu{sup 2+} phosphor exhibits strong thermal quenching resistance. • Two different Eu{sup 2+} emission centers exists in Sr{sub 10}(PO{sub 4}){sub 6}O. • The activation energy was also estimated for the Eu{sup 2+} luminescence center.

  20. Characterization of Physical Properties of Supported Phospholipid Membranes Using Imaging Ellipsometry at Optical Wavelengths

    PubMed Central

    Howland, Michael C.; Szmodis, Alan W.; Sanii, Babak; Parikh, Atul N.

    2007-01-01

    Subnanometer-scale vertical z-resolution coupled with large lateral area imaging, label-free, noncontact, and in situ advantages make the technique of optical imaging ellipsometry (IE) highly suitable for quantitative characterization of lipid bilayers supported on oxide substrates and submerged in aqueous phases. This article demonstrates the versatility of IE in quantitative characterization of structural and functional properties of supported phospholipid membranes using previously well-characterized examples. These include 1), a single-step determination of bilayer thickness to 0.2 nm accuracy and large-area lateral uniformity using photochemically patterned single 1,2-dimyristoyl-sn-glycero-3-phosphocholine bilayers; 2), hydration-induced spreading kinetics of single-fluid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers to illustrate the in situ capability and image acquisition speed; 3), a large-area morphological characterization of phase-separating binary mixtures of 1,2-dilauroyl-sn-glycero-3-phosphocholine and galactosylceramide; and 4), binding of cholera-toxin B subunits to GM1-incorporating bilayers. Additional insights derived from these ellipsometric measurements are also discussed for each of these applications. Agreement with previous studies confirms that IE provides a simple and convenient tool for a routine, quantitative characterization of these membrane properties. Our results also suggest that IE complements more widely used fluorescence and scanning probe microscopies by combining large-area measurements with high vertical resolution without the use of labeled lipids. PMID:17142265

  1. Physical characterization of radioactive sludges in selected Melton Valley and evaporator facility storage tanks

    SciTech Connect

    Ceo, R.N.; Sears, M.B.; Shor, J.T.

    1990-10-01

    Physical measurements were performed on typical radioactive sludge samples from selected Melton Valley Storage Tanks (MVSTs) and evaporator facility storage tanks at ORNL. These measurements included viscosity, particle size, density, sedimentation rate, and solids content. The techniques developed during this project are simple and use inexpensive apparatus to assay the range of physical properties spanned by the sample set. The report provides data in support of the design of the proposed Waste Handling and Packaging Plant, and research and development activities in developing waste management alternatives. 5 refs., 11 figs., 6 tabs.

  2. Issues with the Application of Thermographic Phosphors to Measure High Temperatures in a Gas Turbine Engines

    NASA Astrophysics Data System (ADS)

    Khalid, A. H.; Kontis, K.

    2009-01-01

    The demand for more efficient engines is increasing as concerns over greenhouse gases continue to grow. Performance can be increased if higher turbine inlet temperatures are achieved. However, this increases the chance of material failure. Therefore, the optimum temperature is prescribed by the balance between the benefits of thermal efficiency and material life. To ensure safety and reliability, uncertainty in temperature measurement forces the engine to be operated below its thermal design limit. Accurate surface measurement offers the potential to increase engine performance by allowing them to operate closer to this limit. It can allow designers to better understand flow physics, and greatly facilitate the testing and development of newer thermal protection systems and concepts. The aim of this paper is to highlight the motivations of using phosphor thermometry in gas turbine environments as an alternative to current measurement methods such as discrete thermocouple measurements and pyrometry. Phosphor thermometry offers many advantages over conventional techniques. However, the harsh, high temperature and fast rotating environment presents some unique challenges and the paper further aims to discuss the issues that would arise in such environments. There will be increasing blackbody radiation, restrictions to optical access and time available to collect emissions. There will be imposed upper and lower temperature limits and other restrictions that will greatly influence the design of the measurement system, including the choice of phosphor, bonding technique, excitation and detection methodologies. A system would have to be bespoke to suit the end measurement goal.

  3. High Efficiency Colloidal Quantum Dot Phosphors

    SciTech Connect

    Kahen, Keith

    2013-12-31

    The project showed that non-Cd containing, InP-based nanocrystals (semiconductor materials with dimensions of ~6 nm) have high potential for enabling next-generation, nanocrystal-based, on chip phosphors for solid state lighting. Typical nanocrystals fall short of the requirements for on chip phosphors due to their loss of quantum efficiency under the operating conditions of LEDs, such as, high temperature (up to 150 °C) and high optical flux (up to 200 W/cm2). The InP-based nanocrystals invented during this project maintain high quantum efficiency (>80%) in polymer-based films under these operating conditions for emission wavelengths ranging from ~530 to 620 nm. These nanocrystals also show other desirable attributes, such as, lack of blinking (a common problem with nanocrystals which limits their performance) and no increase in the emission spectral width from room to 150 °C (emitters with narrower spectral widths enable higher efficiency LEDs). Prior to these nanocrystals, no nanocrystal system (regardless of nanocrystal type) showed this collection of properties; in fact, other nanocrystal systems are typically limited to showing only one desirable trait (such as high temperature stability) but being deficient in other properties (such as high flux stability). The project showed that one can reproducibly obtain these properties by generating a novel compositional structure inside of the nanomaterials; in addition, the project formulated an initial theoretical framework linking the compositional structure to the list of high performance optical properties. Over the course of the project, the synthetic methodology for producing the novel composition was evolved to enable the synthesis of these nanomaterials at a cost approximately equal to that required for forming typical conventional nanocrystals. Given the above results, the last major remaining step prior to scale up of the nanomaterials is to limit the oxidation of these materials during the tens of

  4. Apparatuses and methods for laser reading of thermoluminescent phosphors

    DOEpatents

    Braunlich, Peter F.; Tetzlaff, Wolfgang

    1989-01-01

    Apparatuses and methods for rapidly reading thermoluminescent phosphors to determine the amount of luminescent energy stored therein. The stored luminescent energy is interpreted as a measure of the total exposure of the thermoluminescent phosphor to ionizing radiation. The thermoluminescent phosphor reading apparatus uses a laser to generate a laser beam. The laser beam power level is monitored by a laser power detector and controlled to maintain the power level at a desired value or values which can vary with time. A shutter or other laser beam interrupting means is used to control exposure of the thermoluminescent phosphor to the laser beam. The laser beam can be equalized using an opitcal equalizer so that the laser beam has an approximately uniform power density across the beam. The heated thermoluminescent phosphor emits a visible or otherwise detectable luminescent emission which is measured as an indication of the radiation exposure of the thermoluminscent phosphors. Also disclosed are preferred signal processing and control circuits including one system using a digital computer. Also disclosed are time-profiled laser power cycles for pre-anneal, read and post-anneal treatment of phosphors.

  5. A relative-intensity two-color phosphor thermography system

    NASA Technical Reports Server (NTRS)

    Merski, N. Ronald

    1991-01-01

    The NASA LaRC has developed a relative-intensity two-color phosphor thermography system. This system has become a standard technique for acquiring aerothermodynamic data in LaRC Hypersonic Facilities Complex (HFC). The relative intensity theory and its application to the LaRC phosphor thermography system is discussed along with the investment casting technique which is critical to the utilization of the phosphor method for aerothermodynamic studies. Various approaches to obtaining quantitative heat transfer data using thermographic phosphors are addressed and comparisons between thin-film data and thermographic phosphor data on an orbiter-like configuration are presented. In general, data from these two techniques are in good agreement. A discussion is given on the application of phosphors to integration heat transfer data reduction techniques (the thin film method) and preliminary heat transfer data obtained on a calibration sphere using thin-film equations are presented. Finally, plans for a new phosphor system which uses target recognition software are discussed.

  6. Compact fluorescent lamp phosphors in accidental radiation monitoring.

    PubMed

    Murthy, K V R; Pallavi, S P; Ghildiyal, Rahul; Parmar, Manish C; Patel, Y S; Ravi Kumar, V; Sai Prasad, A S; Natarajan, V; Page, A G

    2006-01-01

    The application of lamp phosphors for accidental dosimetry is a new concept. Since the materials used in fluorescent lamps are good photo luminescent materials, if one can either use the inherent defects present in the phosphor or add suitable modifiers to induce thermoluminescence (TL) in these phosphors, then the device (fluorescent lamp) can be used as an accidental dosemeter. In continuation of our search for a suitable phosphor material, which can serve both as an efficient lamp phosphor and as a good radiation monitoring device, detailed examination has been carried out on cerium and terbium-doped lanthanum phosphate material. A (90)Sr beta source with 50 mCi strength (1.85 GBq) was used as the irradiation source for TL studies. The TL response as a function of dose received was examined for all phosphors used and it was observed that the intensity of the TL peak vs. dose received was a linear function in the dose range 0.1-200 Gy in each case. Incidentally LaPO(4): Ce,Tb is a component of the compact fluorescent lamp marketed recently as an energy bright light source. Besides having very good luminescence efficiency, good dosimetric properties of these phosphors render them useful for their use in accidental dosimetry also. PMID:16816401

  7. Highly efficient all-nitride phosphor-converted white light emitting diode

    NASA Astrophysics Data System (ADS)

    Mueller-Mach, Regina; Mueller, Gerd; Krames, Michael R.; Höppe, Henning A.; Stadler, Florian; Schnick, Wolfgang; Juestel, Thomas; Schmidt, Peter

    2005-07-01

    In the Editor's Choice [1] the development and demonstration of a highly efficient warm-white all-nitride phosphor-converted light emitting diode (pc-LED) is presented utilizing a GaN based quantum well blue LED and two novel nitrogen containing luminescent materials doped with Eu2+. These novel LEDs are superior to both incandescent and fluorescent lamps and may therefore become the next generation of general lighting sources.The cover picture is an artist's view of the 2-pc-LED: On a copper slug and underneath a plastic lens a flip-chip is soldered to metal contacts; flip-chip meaning the substrate on which the stack of GaN and InGaN layers has been deposited is used as light exit, the (bottom) p-contacts being highly reflective. The color converting phosphors are placed on top of the chip, embedded in silicone. Primary blue as well as color-converted red and green photons are emitted.The first author, Regina Mueller-Mach, manages the Charac-terization Laboratory at Lumileds which runs R&D work on phosphor converted LEDs in close cooperation with Philips Research Laboratories and the Department of Chemistry and Biochemistry of the University of Munich.

  8. Synthesis and luminescence study of BaZrO3:Eu3+ phosphor

    NASA Astrophysics Data System (ADS)

    Parganiha, Yogita; Kaur, Jagjeet; Dubey, Vikas; Shrivastava, Ravi; Dhoble, S. J.

    2015-12-01

    The phosphor of BaZrO3 doped with different concentration of Eu3+ ions (0.1, 0.5, 1 mol%) was prepared by solid-state reaction method. The prepared samples were characterized by X-ray diffraction (XRD), photoluminescence (PL) and thermoluminescence (TL) techniques. Analysis of XRD data shows the formation of perovskite structure of prepared phosphor. The room temperature excitation spectra vary with the Eu3+ concentration and consist of an intense charge transfer band and weak f-f transitions. The PL emission spectra, excited at 254 nm, consist of 4f-4f emission transitions from the 5D0 excited level of the Eu3+ ions to the 7FJ (J = 0-3) levels. The dependence of luminescence intensity on the Eu3+ concentration in BaZrO3:Eu3+ was studied. The present phosphor can act as single host for intense red emission for display devices application. Commission internationale de I'Eclairage techniques gives information about correlated color temperature and prominent emissions in PL emission spectra. Detail process and possible mechanism for PL and TL are studied and discussed in this paper. For the variable concentration of Eu3+ ions on PL studies shows the PL intensity increase with increasing the concentration of dopant. In TL glow curve the optimized concentration in 1 mol% for UV irradiated sample. The kinetic parameters were calculated by computerized glow curve deconvolution (CGCD) technique.

  9. Rapid synthesis and luminescence properties of Sr3SiO5:Eu2+ phosphors

    NASA Astrophysics Data System (ADS)

    Sun, Jiacheng; Mi, Xiaoyun; Ma, Jing; Su, Jiangang; Xia, Wei; Zhang, Lei; Bai, Zhaohui; Zhang, Xiyan

    2016-03-01

    Sr3SiO5:Eu2+ phosphors were synthesized rapidly through a microwave sintering method with the presence of activated carbon powder. The detailed composition and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influences of sintering time, fluxing agent (BaF2) content and rare earth ion doping concentration on its photoluminescence (PL) properties were also investigated. It was clear in PL spectra that a broad emission band peaking at 570nm was obtained in as-prepared phosphors under a blue light excitation. Meanwhile, non-radiative transitions between Eu2+ ions in the Sr3SiO5 host had also been demonstrated to be attributable to dipole-dipole interactions, and the critical distance calculated by the quenching concentration was estimated to be 10.56 Å. The samples were uniform in diameter and regular in morphology. In other words, the Sr3SiO5:Eu2+ phosphors possessed a potential application for white light emitting diodes (LEDs).

  10. Structure and spectroscopic properties of (Y, Eu)(PO3)3 polyphosphate red phosphors

    NASA Astrophysics Data System (ADS)

    Zhang, Xinguo; Chen, Peican; Wang, Zizhou; Zhou, Liya; Zhou, Fangxiang

    2016-08-01

    A series of orange-red emitting phosphor Y(PO3)3: xEu3+ (x = 0.1-1.0) was prepared by a solid-state reaction route. The phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) as well as decay lifetimes. Studies revealed the phase transfer from monoclinic to orthorhombic when Y3+ is totally replaced by Eu3+, and expansion of the unit cell occurs with increasing Eu3+ doped content. The PL spectra show that the phosphors Y(PO3)3: xEu3+ can be effectively excited by near ultraviolet (n-UV) light, and exhibit strong red-orange emission with no concentration quenching. The profile of PL spectra changes significantly at high Eu3+ content (x ≥ 0.80), which is due to the variation of preference for substitution of Eu3+. The luminescence due to the 5D0 → 7FJ (J = 1, 2) transitions at 77 K exhibits its own spectral features for different crystallographic site. It is found that Eu3+ ions occupy the centers of octahedral polyhedron and form Ci/C1 point group in Y(PO3)3.

  11. The photoluminescence properties of tri-colour silicoaluminate phosphors prepared from oil shale ash

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Song, Yanhua; Sheng, Ye; Zheng, Keyan; Ding, Shizhou; Yuan, Bo; Xu, Xuechun; Zou, Haifeng

    2015-09-01

    In this paper, high value-added tri-colour phosphors Ba0.96Mg1.88Si2O7:0.02Eu2+, 0.02Dy3+, 0.12Mn2+; CaSr0.995SiO4:0.005Eu2+ and Ba0.91MgAl10O17:0.09Eu2+ were prepared using the white carbon black (hereinafter referred to as WCB) and alumina extracted from oil shale ash as raw materials. The structure and luminescence properties of the samples were characterized by X-ray diffraction (XRD) and photoluminescent spectra. The results show that the red and green phosphors synthesized by WCB exhibited much weaker emission than the phosphors synthesized by pure chemical reagent silica, which is mainly due to the high content of iron in the WCB. After purifying the WCB under laboratory conditions, the luminescence properties were improved and close to that of pure chemical reagent. By comparing with the emission of the samples synthesized with chemical reagents, the results show that the products extracted from oil shale ash can be applied to synthesize luminescent materials which have potential applications in white-light ultraviolet (UV)-LED field.

  12. Effect of Silica Nanoparticles on the Photoluminescence Properties of BCNO Phosphor

    NASA Astrophysics Data System (ADS)

    Nuryadin, Bebeh W.; Faryuni, Irfana Diah; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal, Khairurrijal

    2011-12-01

    Effect of additional silica nanoparticles on the photoluminescence (PL) performance of boron carbon oxy-nitride (BCNO) phosphor was investigated. As a precursor, boric acid and urea were used as boron and nitrogen sources, respectively. The carbon sources was polyethylene glycol (PEG) with average molecule weight 20000 g/mol.. Precursor solutions were prepared by mixing these raw materials in pure water, followed by stirring to achieve homogeneous solutions. In this precursor, silica nanoparticles were added at various mass ratio from 0 to 7 %wt in the solution. The precursors were then heated at 750 °C for 60 min in a ceramic crucible under atmospheric pressure. The photoluminescence (PL) spectrum that characterized by spectrophotometer showed a single, distinct, and broad emission band varied from blue to near red color, depend on the PEG, boric acid and urea ratio in the precursor. The addition of silica nanoparticles caused the increasing of PL intensity as well as the shifting of peak wavelength of PL spectrum. The peak shifting of PL was affected by the concentration of silica nanoparticles that added into the precursor. We believe that the BCNO-silica composite phosphor becomes a promising material for the phosphor conversion-based white light-emitting diodes.

  13. Shock-compression on Eu2O3 doped pollucite phosphors

    NASA Astrophysics Data System (ADS)

    Hamada, Sho; Kishimura, Hiroaki; Aruga, Atsushi; Matsumoto, Hitoshi

    2015-06-01

    Pollucite CsAlSi2O6 is a natural mineral belong to zeolite group formed with analcime, and general formula is following: (Cs,Na)16Al16Si32O96 .n(H2O). The crystal structure of pure CsAlSi2O6 is cubic(Ia-3d) and unit cell is 136645 nm Pollucite is stable stone yielding on the surface of the Earth since ancient times and is used to as a raw material of Cs element. Eu2O3-doped pollucite phosphors are efficient white phosphor for Application of deep-UV -light emitting diode (LED). Phosphors were prepared by solid-state reaction. 1 mol% Eu2O3-doped and 3 mol% Eu2O3-doped pollucites were prepared. Shock-recovery experiments were conducted involving the impact of a flyer plate accelerated by a single-stage powder-propellant gun. The recovered samples were characterized by X-ray diffraction (XRD) analysis and photoluminescence (PL) spectroscopy. The XRD and PL results of samples shocked at pressures of 22 GPa indicated that dissolution and amorphous-to-crystalline transformation occurred. In addition, emission peak wavelength of 3 mol% Eu2O3-doped sample shift 20 nm (520 -->500 nm). As a result, it is considered that Eu2+ moved in the crystalline by shock-compression.

  14. Phosphorous adsorption and precipitation in a permeable reactive wall: Applications for wastewater disposal systems

    SciTech Connect

    Baker, M.J.; Blowes, D.W. |; Placek, C.J. |

    1997-12-31

    A permeable reactive mixture has been developed using low cost, readily available materials that is capable of providing effective, long-term phosphorous treatment in areas impacted by on-land wastewater disposal. The reactive mixture creates a geochemical environment suitable for P-attenuation by both adsorption and precipitation reactions. Potential benefits include significant reductions in phosphorous loading to receiving groundwater and surface water systems, and the accumulation of P-mass in a finite and accessible volume of material. The mixture may be applied as a component within surface treatment systems or in subsurface applications such as horizontal or vertical permeable reactive walls. The mixture averaged > 90% treatment efficiency over 3.6 years of continuous-flow laboratory column experiments. The mixture was further evaluated at the pilot-scale to treat municipal wastewater, and the field-scale to treat a well-characterized septic system plume using an in situ funnel and gate system. Average PO{sub 4}-P concentrations in effluent exiting the reactive mixture range between 0 - 0.3 mg/L. Mineralogical analyses have isolated the phases responsible for phosphorous uptake, and discrete phosphate precipitates have been identified.

  15. CHARACTERIZATION AND PHYSICAL MAPPING OF MAIZE BAC LIBRARIES USING HIGH DENSITY BAC FILTER HYBRIDIZATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A HindIII and an EcoRI maize BAC library have been constructed from maize inbred line B73. Use of both libraries to make a physical map should minimize the under representation of certain genomic regions caused by the use of a particular restriction enzyme. High-density filter sets from the two libr...

  16. THE PHYSICAL AND CHEMICAL CHARACTERIZATION OF THE EMISSIONS FROM A RESIDENTIAL OIL BOILER

    EPA Science Inventory

    The toxicity of emissions from the combustion of home heating oil and the use of residential oil boilers (ROB) is an important health concern. Yet scant physical and chemical information about the emissions from this source are available for dispersion, climate, and source-recep...

  17. Physical modeling of interference enhanced imaging and characterization of single nanoparticles.

    PubMed

    Avci, Oguzhan; Adato, Ronen; Ozkumur, Ayca Yalcin; Ünlü, M Selim

    2016-03-21

    Interferometric imaging schemes have gained significant interest due to their superior sensitivity over imaging techniques that are solely based on scattered signal. In this study, we outline the theoretical foundations of imaging and characterization of single nanoparticles in an interferometric microscopy scheme, examine key parameters that influence the signal, and benchmark the model against experimental findings. PMID:27136804

  18. Physical and chemical characterization of residual oil-fired power plant emissions

    EPA Science Inventory

    Although the toxicity of oil combustion emissions is a significant public health concern, few studies characterize the emissions from plant-scale utility boilers firing residual oil. This study remedies that deficiency by sampling and monitoring stack emissions from a 432 Giga Jo...

  19. Localized surface plasmon enhanced cathodoluminescence from Eu3+-doped phosphor near the nanoscaled silver particles.

    PubMed

    Lee, Seong Min; Choi, Kyung Cheol; Kim, Dong Hyuk; Jeon, Duk Young

    2011-07-01

    We elucidate that the luminescence from Eu3+-doped phosphor excited by the electron collision can be modified on location near the metallic nanoparticles. The Eu3+-doped phosphor was fabricated on the nanoscaled Ag particles ranging of 5 nm to 30 nm diameter. As a result of the cathodoluminescence measurements, the phosphor films on the Ag particles showed up to twofold more than that of an isolated phosphor film. Enhanced cathodoluminescence originated from the resonant coupling between the localized surface plasmon of Ag nanoparticles and radiating energy of the phosphor. Cathodoluminescent phosphor for high luminous display devices can be addressed by locating phosphor near the surface of metallic nanoparticles. PMID:21747476

  20. Physical and spectral characterization of the human cyclin A gene and its interactions with anthracycline anticancer drugs

    NASA Astrophysics Data System (ADS)

    Bao, Huixin; Wang, Xiaohui; Yu, Haijia; Fu, Manliang; Qu, Xiaogang; Zheng, Yongchen; Ren, Jinsong

    2007-02-01

    Over expression of cyclin A in human tumors has been linked to cancer by various experimental lines of evidence. However, physical and spectral characterization of the human cyclin A gene and its interactions with anticancer drugs have not been reported. Our gene sequence analysis, singular value decomposition method and melting studies in the presence of antitumor agents, daunomycin, doxorubicin and Hoechst 33258 showed that cyclin A gene had both AT-rich and GC-rich domains. For a ligand with unknown DNA binding specificity, this gene sequence can be used to differentiate its DNA binding preference.