Science.gov

Sample records for pulse radiolysis method

  1. Applications of pulse radiolysis to imaging sciences

    SciTech Connect

    Meisel, D.

    1996-05-01

    Pulse radiolysis has been used over the last 3 decades to study a variety of physical and chemical systems, including those relevant to imaging processes. This review outlines the similarities between photolysis and radiolysis and highlight the differences. It focuses on time-resolved variants of the two disciplines, flash photolysis vs pulse radiolysis. The strength (and weakness) of the radiolytic techniques is their nonspecificity; the energy is always absorbed by the solvent and not the solute. Radiation chemistry principles that were developed for one discipline are easily transportable to another. The pulse radiolysis technique with a wide arsenal of detection techniques is currently used to identify short-lived intermediates and to determine their kinetic and thermodynamic properties. Together, these studies provide mechanistic insight into the behavior of physical systems. We demonstrate the utility of the approach in several areas of interest to imaging sciences: clustering of silver atoms, growth of silver halides, and medium effects on these systems.

  2. [Pulsed radiolysis of aqueous solutions of serum albumin containing naphthoquinones].

    PubMed

    Pribush, A G; Savich, A V

    1987-01-01

    As was shown by the pulse radiolysis method the simultaneous presence of naphthoquinone and human serum albumin molecules in an aqueous solution leads to the adsorption of the former on the surface of the latter. It is suggested that in these conditions the protein tertiary structure changes. New conformation reduces the reactivity of albumin toward the hydrated electron. PMID:3628723

  3. Pulse Radiolysis of Aqueous Thiocyanate Solution

    SciTech Connect

    Milosavljevic, Bratoljub H.; LaVerne, Jay A.

    2005-01-13

    The pulse radiolysis of N2O saturated aqueous solutions of KSCN was studied under neutral pH conditions. The observed optical absorption spectrum of the SCN• radical in solution is more complex than previously reported, but it is in good agreement with that measured in the gas phase. Kinetic traces at 330 nm and 472 nm corresponding to SCN• and (SCN)2•¯, respectively, were fit using a Monte Carlo simulation kinetic model. The rate coefficient for the oxidation of SCN¯ ions by OH radicals, an important reaction used in competition kinetics measurements, was found to be 1.4 ± 0.1 x 1010 M-1 s-1, about 30 % higher than the normally accepted value. A detailed discussion of the reaction mechanism is presented.

  4. Pulse radiolysis studies of melatonin and chloromelatonin.

    PubMed

    Roberts, J E; Hu, D N; Wishart, J F

    1998-02-01

    The endogenous indole melatonin and the melatonin receptor agonist 6-chloromelatonin block the proliferation of both dermal and uveal melanoma cells by mechanisms that may involve redox reactions. The interactions of hydrated electrons, the azide radical, hydroxyl radicals and superoxide with melatonin and its 6-chloro analogue have been studied using the technique of pulse radiolysis. The reaction rate constants of eaq- and N3 x with these compounds were found to be dependent on substitution at the sixth position. The rate constants for reaction of 6-chloromelatonin and melatonin with solvated electrons are 4.5 x 10(9) M-1 s-1 and 4.2 x 10(8) M-1 s-1, respectively. The reaction rate constants of N3 x with malatonin and chloromelatonin are 9.8 x 10(9) M-1 s-1 and 3.5 x 10(9) M-1 s-1 and 3.5 x 10(9) M-1 s-1, respectively. Melatonin and 6-chloromelatonin react with hydroxyl radicals at near diffusion controlled rates (1.3 x 10(10) M-1 s-1, 8.2 x 10(9) M-1 s-1). Melatonin and 6-chloromelatonin did not react with superoxide radicals and we calculate an upper limit of 1.0 x 10(4) M-1 s-1 for the rate constant for reaction of melatonin and 6-chloromelatonin with superoxide ion. PMID:9540219

  5. Pulse radiolysis studies on superoxide reductase from Treponema pallidum.

    PubMed

    Nivière, V; Lombard, M; Fontecave, M; Houée-Levin, C

    2001-05-25

    Superoxide reductases (SORs) are small metalloenzymes, which catalyze reduction of O2*- to H2O2. The reaction of the enzyme from Treponema pallidum with superoxide was studied by pulse radiolysis methods. The first step is an extremely fast bi-molecular reaction of the ferrous center with O2, with a rate constant of 6 x 10 (8) M(-1) s(-1). A first intermediate is formed which is converted to a second one with a slower rate constant of 4800 s(-1). This latter value is 10 times higher than the corresponding one previously reported in the case of SOR from Desulfoarculus baarsii. The reconstituted spectra for the two intermediates are consistent with formation of transient iron-peroxide species. PMID:11377434

  6. Development of nanosecond time-resolved infrared detection at the LEAF pulse radiolysis facility

    DOE PAGESBeta

    Grills, David C.; Farrington, Jaime A.; Layne, Bobby H.; Preses, Jack M.; Bernstein, Herbert J.; Wishart, James F.

    2015-04-27

    When coupled with transient absorption spectroscopy, pulse radiolysis, which utilizes high-energy electron pulses from an accelerator, is a powerful tool for investigating the kinetics and thermodynamics of a wide range of radiation-induced redox and electron transfer processes. The majority of these investigations detect transient species in the UV, visible, or near-IR spectral regions. Unfortunately, the often-broad and featureless absorption bands in these regions can make the definitive identification of intermediates difficult. Time-resolved vibrational spectroscopy would offer much improved structural characterization, but has received only limited application in pulse radiolysis. In this paper, we describe in detail the development of amore » unique nanosecond time-resolved infrared (TRIR) detection capability for condensed-phase pulse radiolysis on a new beam line at the LEAF facility of Brookhaven National Laboratory. The system makes use of a suite of high-power, continuous wave external-cavity quantum cascade lasers as the IR probe source, with coverage from 2330-1051 cm⁻¹. The response time of the TRIR detection setup is ~40 ns, with a typical sensitivity of ~100 µOD after 4-8 signal averages using a dual-beam probe/reference normalization detection scheme. As a result, this new detection method has enabled mechanistic investigations of a range of radiation-induced chemical processes, some of which are highlighted here.« less

  7. Development of nanosecond time-resolved infrared detection at the LEAF pulse radiolysis facility

    SciTech Connect

    Grills, David C.; Farrington, Jaime A.; Layne, Bobby H.; Preses, Jack M.; Bernstein, Herbert J.; Wishart, James F.

    2015-04-27

    When coupled with transient absorption spectroscopy, pulse radiolysis, which utilizes high-energy electron pulses from an accelerator, is a powerful tool for investigating the kinetics and thermodynamics of a wide range of radiation-induced redox and electron transfer processes. The majority of these investigations detect transient species in the UV, visible, or near-IR spectral regions. Unfortunately, the often-broad and featureless absorption bands in these regions can make the definitive identification of intermediates difficult. Time-resolved vibrational spectroscopy would offer much improved structural characterization, but has received only limited application in pulse radiolysis. In this paper, we describe in detail the development of a unique nanosecond time-resolved infrared (TRIR) detection capability for condensed-phase pulse radiolysis on a new beam line at the LEAF facility of Brookhaven National Laboratory. The system makes use of a suite of high-power, continuous wave external-cavity quantum cascade lasers as the IR probe source, with coverage from 2330-1051 cm⁻¹. The response time of the TRIR detection setup is ~40 ns, with a typical sensitivity of ~100 µOD after 4-8 signal averages using a dual-beam probe/reference normalization detection scheme. As a result, this new detection method has enabled mechanistic investigations of a range of radiation-induced chemical processes, some of which are highlighted here.

  8. Development of nanosecond time-resolved infrared detection at the LEAF pulse radiolysis facility

    SciTech Connect

    Grills, David C. Farrington, Jaime A.; Layne, Bobby H.; Preses, Jack M.; Wishart, James F.; Bernstein, Herbert J.

    2015-04-15

    When coupled with transient absorption spectroscopy, pulse radiolysis, which utilizes high-energy electron pulses from an accelerator, is a powerful tool for investigating the kinetics and thermodynamics of a wide range of radiation-induced redox and electron transfer processes. The majority of these investigations detect transient species in the UV, visible, or near-IR spectral regions. Unfortunately, the often-broad and featureless absorption bands in these regions can make the definitive identification of intermediates difficult. Time-resolved vibrational spectroscopy would offer much improved structural characterization, but has received only limited application in pulse radiolysis. In this paper, we describe in detail the development of a unique nanosecond time-resolved infrared (TRIR) detection capability for condensed-phase pulse radiolysis on a new beam line at the LEAF facility of Brookhaven National Laboratory. The system makes use of a suite of high-power, continuous wave external-cavity quantum cascade lasers as the IR probe source, with coverage from 2330 to 1051 cm{sup −1}. The response time of the TRIR detection setup is ∼40 ns, with a typical sensitivity of ∼100 μOD after 4-8 signal averages using a dual-beam probe/reference normalization detection scheme. This new detection method has enabled mechanistic investigations of a range of radiation-induced chemical processes, some of which are highlighted here.

  9. Development of nanosecond time-resolved infrared detection at the LEAF pulse radiolysis facility

    NASA Astrophysics Data System (ADS)

    Grills, David C.; Farrington, Jaime A.; Layne, Bobby H.; Preses, Jack M.; Bernstein, Herbert J.; Wishart, James F.

    2015-04-01

    When coupled with transient absorption spectroscopy, pulse radiolysis, which utilizes high-energy electron pulses from an accelerator, is a powerful tool for investigating the kinetics and thermodynamics of a wide range of radiation-induced redox and electron transfer processes. The majority of these investigations detect transient species in the UV, visible, or near-IR spectral regions. Unfortunately, the often-broad and featureless absorption bands in these regions can make the definitive identification of intermediates difficult. Time-resolved vibrational spectroscopy would offer much improved structural characterization, but has received only limited application in pulse radiolysis. In this paper, we describe in detail the development of a unique nanosecond time-resolved infrared (TRIR) detection capability for condensed-phase pulse radiolysis on a new beam line at the LEAF facility of Brookhaven National Laboratory. The system makes use of a suite of high-power, continuous wave external-cavity quantum cascade lasers as the IR probe source, with coverage from 2330 to 1051 cm-1. The response time of the TRIR detection setup is ˜40 ns, with a typical sensitivity of ˜100 μOD after 4-8 signal averages using a dual-beam probe/reference normalization detection scheme. This new detection method has enabled mechanistic investigations of a range of radiation-induced chemical processes, some of which are highlighted here.

  10. Oxidation of aqueous polyselenide solutions. A mechanistic pulse radiolysis study

    SciTech Connect

    Goldbach, A.; Saboungi, M.L.; Johnson, J.A.; Cook, A.R.; Meisel, D.

    2000-05-04

    The oxidation of aqueous polyselenide solutions was studied by pulse radiolysis in the presence of N{sub 2}O at pH 12.3; the hydroxyl radical OH was the predominant oxidant, while hydrogen selenide anions HSe{sup {minus}} and triselenide dianions Se{sub 3}{sup 2{minus}} were the major selenide species in the starting solution. The progress of the oxidation was monitored by optical spectroscopy. Transient polyselenides appeared immediately after the electron pulse and rapidly proceeded to form adducts with HSe{sup {minus}}, i.e., HSe{sub 2}{sup 2{minus}} and H{sub 2}Se{sub 2}{sup {minus}}, and a fairly long-lived intermediate that was identified as the diselenide radical anion Se{sub 2}{sup {minus}}. These radicals recombine to give eventually the tetraselenide dianion, Se{sub 4}{sup 2{minus}}.

  11. Pulse radiolysis of aqueous solutions of sodium tetraphenylborate

    NASA Astrophysics Data System (ADS)

    Crawford, Charles L.; Gholami, Mohammad R.; Bhave, Ravindra N.; Hanrahan, Robert J.

    1994-09-01

    In previous work on the 60Co γ-radiolysis of aqueous tetraphenylborate (TPB -) solutions carried out in this laboratory, it was found that several organic products, including benzene, phenol and biphenyl, are produced with substantial yield. However, the reaction mechanism was not established. In the present study, reactions initiated by OḢ radicals, N 3 radicals and e -aq in aqueous TPB - solutions were studied by pulse radiolysis using a 600 keV Febetron electron accelerator. The lack of reactivity between TPB - and e -aq was demonstrated by directly monitoring the transient optical absorbance of e -aq. Concerning the reaction with O Ḣ, two schemes were considered: (1) electron transfer from B(C 6H 5) -4 to O Ḣ; or (2) O Ḣ addition to B(C 6H 5) -4. Comparison of observed transient absorption spectra with expectations based on two different schemes suggests that O Ḣ addition is the dominant reaction pathway under conditions of N 2O saturation, with an experimentally determined second-order rate constant of 6.2×10 9M -1s -1. A mechanism based on an initial first-order self-decomposition of the O Ḣ adduct, (C 6H 5) 3BC 6H 5OH -· with a measured rate constant of 4×10 4s -1 is proposed. Kinetic modeling on the proposed mechanistic scheme gives good agreement with our experimental results.

  12. Pulse radiolysis studies in supercritical CO{sub 2}

    SciTech Connect

    Jonah, C. D.; Dimitrijevic, N. M.; Bartels, D. M.; Takahashi, K.

    2000-03-09

    The pulse radiolysis technique has been applied to study reactions of ions in supercritical solutions. Evidence for the formation of C{sub 2}O{sub 4}{sup +} has been found in supercritical CO{sub 2}. The rate of the electron transfer reaction from dimethyl aniline to the C{sub 2}O{sub 4}{sup +} was measured over the density range of 0.17--0.7 g/cm{sup 3}. The reaction rate was measured to be close to diffusion-controlled at the lowest density; at higher densities, the rate was considerably below the apparent diffusion-controlled rate. Similar behavior was found for the reaction of the anion (presumably C{sub 2}O{sub 4}{sup {minus}}) with benzoquinone. The reaction of O{sub 2} with C{sub 2}O{sub 4}{sup +} was considerably slower than the expected diffusion-controlled rate.

  13. Pulse radiolysis and spectrophotometric studies on the binding of organic cations with heparin

    NASA Astrophysics Data System (ADS)

    Jakubowska, Małgorzata; Adamus, Jan; Gębicki, Jerzy; Marcinek, Andrzej; Sikora, Adam

    2014-06-01

    Here we present the spectroscopic and pulse radiolysis studies of the interactions of heparin and some organic cations:methylene blue (MB), 1-methylnicotinamide (MNA+), and its dimer 1,3-bis(1-methylnicotinamide)propane (bis(MNA+)).

  14. Development of high-voltage pulse-slicer unit with variable pulse duration for pulse radiolysis system

    NASA Astrophysics Data System (ADS)

    Upadhyay, J.; Sharma, M. L.; Navathe, C. P.; Toley, M. A.; Shinde, S. J.; Nadkarni, S. A.; Sarkar, S. K.

    2012-02-01

    A high-voltage pulse-slicer unit with variable pulse duration has been developed and integrated with a 7 MeV linear electron accelerator (LINAC) for pulse radiolysis investigation. The pulse-slicer unit provides switching voltage from 1 kV to 10 kV with rise time better than 5 ns. Two MOSFET based 10 kV switches were configured in differential mode to get variable duration pulses. The high-voltage pulse has been applied to the deflecting plates of the LINAC for slicing of electron beam of 2 μs duration. The duration of the electron beam has been varied from 30 ns to 2 μs with the optimized pulse amplitude of 7 kV to get corresponding radiation doses from 6 Gy to 167 Gy.

  15. Pulse radiolysis in water with heavy-ion beams. A short review

    NASA Astrophysics Data System (ADS)

    Baldacchino, G.

    2008-10-01

    This article presents a short review of the studies in radiation chemistry of liquid water with heavy ions, which have used pulse radiolysis methods during the last 20 years. The interests and the difficulties of developing this kind of experiment are depicted. The linear energy transfer (LET) effect is the main topic of these studies. The earliest effects close to the structure of the deposited energy can be observed directly by transient absorption spectroscopy by following the hydrated electron, the superoxide radical produced in the absence of molecular oxygen and the hydroxyl radical, which still requires the use of scavenger. Finally, the results can be compared to the heterogeneous chemical processes in the time range of 1 ns to 1 μs described by Monte Carlo simulations. The absolute values of the radiolytic yields are still uncertain because of the dosimetry accuracy. The future aspects of the method are discussed in terms of new types of particle accelerators giving better time resolutions.

  16. Hydrated Electrons in a Quaternary Microemulsion System: A Pulse Radiolysis Study

    PubMed

    Adhikari; Joshi; Gopinathan

    1997-07-01

    Using the technique of pulse radiolysis, hydrated electrons have been produced and studied in quaternary microemulsion (sodium lauryl sulfate (NaLS)/water/cyclohexane/1-pentanol) system. Remarkably high lifetimes ( approximately 20 &mgr;s) for hydrated electrons have been obtained. In general, these are two orders of magnitude higher than those reported earlier in reverse micelles. The water droplet sizes and location of the probes have been determined from the decay kinetics of hydrated electrons. The yields and half-lives (t 1/2 ) of the hydrated electrons vary smoothly as the water droplet sizes are changed. We believe that these studies will be useful not only in interpreting electron transfer reactions occurring in small water pockets in biological systems but also in the production of metal nanoclusters by radiation chemical method. PMID:9241228

  17. Time-resolved spectroscopy of solid poly/1-vinyl naphthalene/ following electron beam pulse radiolysis - Pulse radiolytic studies on polymers

    NASA Technical Reports Server (NTRS)

    Coulter, D. R.; Liang, R. H.; Di Stefano, S.; Moacanin, J.; Gupta, A.

    1982-01-01

    Transient emission studies following pulse radiolysis of solid poly(1-vinyl naphthalene) show existence of excited monomers and two excimers. Quenching experiments indicate that excimers are not formed directly by recombination of ions but probably by trapping of migrating monomeric excitation in preformed traps whose density is approximately one in 1000.

  18. Radiation-induced pink nickel oligomeric clusters in water. Pulse radiolysis study.

    PubMed

    Hioul, Mohamed Larbi; Lin, Mingzhang; Belloni, Jacqueline; Keghouche, Nassira; Marignier, Jean-Louis

    2014-10-01

    γ-rays and pulse radiolysis of aqueous solutions of Ni(2+) ions in the presence of polyacrylate (PA(-)) and 2-propanol leads to the formation of metastable species absorbing at 540 nm that are ascribed to "pink" oligomeric clusters of a few nickel atoms only. The molar absorption coefficient is evaluated as ε540 nm = 3300 ± 300 L mol(-1) cm(-1) per Ni(0) atom. The successive steps from the reduction of Ni(2+) into Ni(+) ions to the formation of the pink clusters at 540 nm under conditions of complexation by PA(-) are investigated by pulse radiolysis. The yield of the formation of pink clusters increases markedly with the irradiation dose rate, demonstrating the occurrence of the disproportionation of the [Ni(+), PA(-)] complex after a single electron pulse. The reduction and nucleation mechanisms, including rate constants, in competition with the back oxidation by protons, particularly at low dose rate, are discussed. PMID:25198291

  19. Ultra-fast pulse radiolysis system combined with a laser photocathode RF gun and a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Muroya, Y.; Lin, M.; Watanabe, T.; Wu, G.; Kobayashi, T.; Yoshii, K.; Ueda, T.; Uesaka, M.; Katsumura, Y.

    2002-08-01

    In order to study the early events in radiation physics and chemistry, two kinds of new pulse radiolysis systems with higher time resolution based on pump-and-probe method have been developed at the Nuclear Engineering Research Laboratory, the University of Tokyo. The first one, a few picosecond (2 ps at FWHM) electron beam (pump) from an 18 MeV S-band Linac using a laser photocathode RF gun (BNL/KEK/SHI type: GUN IV) was operated with a femtosecond laser pulse (100 fs at FWHM), which also acted as the analyzing light (probe). The synchronization precision between the pump and the probe was 1.7 ps (rms). In a 1.0 cm sample cell, a time resolution of 12 ps was achieved. The second one, a picosecond (4 ps at FWHM) electron pulse from a 35 MeV S-band Linac employing a conventional thermionic gun with a sub-harmonic buncher, was synchronized with the femtosecond laser pulse, with a synchronization jitter of 2.8 ps (rms). A time resolution of 22 ps was obtained with 2 cm cell. This makes it possible to do the pulse radiolysis experiments in the time range from picosecond to sub-microsecond.

  20. Pulsed Electron Beam Water Radiolysis for Sub-Microsecond Hydroxyl Radical Protein Footprinting

    PubMed Central

    Watson, Caroline; Janik, Ireneusz; Zhuang, Tiandi; Charvátová, Olga; Woods, Robert J.; Sharp, Joshua S.

    2009-01-01

    Hydroxyl radical footprinting is a valuable technique for studying protein structure, but care must be taken to ensure that the protein does not unfold during the labeling process due to oxidative damage. Footprinting methods based on sub-microsecond laser photolysis of peroxide that complete the labeling process faster than the protein can unfold have been recently described; however, the mere presence of large amounts of hydrogen peroxide can also cause uncontrolled oxidation and minor conformational changes. We have developed a novel method for sub-microsecond hydroxyl radical protein footprinting using a pulsed electron beam from a 2 MeV Van de Graaff electron accelerator to generate a high concentration of hydroxyl radicals by radiolysis of water. The amount of oxidation can be controlled by buffer composition, pulsewidth, dose, and dissolved nitrous oxide gas in the sample. Our results with ubiquitin and β-lactoglobulin A demonstrate that one sub-microsecond electron beam pulse produces extensive protein surface modifications. Highly reactive residues that are buried within the protein structure are not oxidized, indicating that the protein retains its folded structure during the labeling process. Time-resolved spectroscopy indicates that the major part of protein oxidation is complete in a timescale shorter than that of large scale protein motions. PMID:19265387

  1. Concentration oscillations of zinc tetra-4-tert-butylphthalocyanine in ethanol in pulsed radiolysis

    SciTech Connect

    Chelnakov, N.P.; Tupikov, V.I.; Danilov, K.E

    1988-07-01

    Deaerated solutions of monomeric zinc tetra-4-tert-butylphthalocyanine (ZnPC) in ethanol were studied by spectrophotometry directly during /gamma/ and pulsed microsecond radiolysis. It was shown that the ZnPC monoanion is formed on decomposition of the extracomplex of ZnPC with the hydroxyethyl radical and subsequent conversion of the monoanion into the starting ZnPC is accompanied by concentration oscillations. A model system of reactions is proposed which describes the experimental characteristics.

  2. Pulse radiolysis study of the reactions of catechins with nitrogen dioxide

    NASA Astrophysics Data System (ADS)

    Gebicki, Jerzy L.; Meisner, Piotr; Stawowska, Katarzyna; Gebicka, Lidia

    2012-12-01

    Nitrogen dioxide (•NO2), one of the oxidizing radicals formed in vivo is suspected to play a role in various pathophysiological processes. The reactions of •NO2 with dietary catechins, the group of flavonoids present in high amounts in green tea and red wine, have been investigated by pulse radiolysis method. The kinetics of the reaction of •NO2 with gallic acid have been also studied for comparison. The spectra of transient intermediates are presented. The rate constants of the reaction of •NO2 with catechin, epigallocatechin, epigallocatechin gallate and gallic acid determined by the competition method with 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) at pH 7.0 and room temperature have been found to be 0.9, 1.0, 2.3 and 0.5×108 M-1 s-1, respectively. The values for catechins are among the highest reported for the reactions of •NO2 with non-radical compounds.

  3. A study on scavenging effects of Chinese medicine on superoxide anion radicals by pulse radiolysis

    NASA Astrophysics Data System (ADS)

    Fengmei, Li; Andong, Liu; Hongchun, Gu; Shaojie, Di

    1993-10-01

    A study on scavenging and dismutation effects on superoxide anion radical (·O -2) by using two Chinese antiaging medicine-Salvia Miltiorrhiza injection (S.M.) and Sulekang capsule (S.C.) were performed by pulse radiolysis. The absorption spectra of ·O -2 have been redetermined in radiolysis of aqueous solution of sodium format. The absorption maximum is at about 250nm. The results suggested that S.M. and S.C. can dismutate and scavenge ·O -2. The experimental scavenging rate of S.M. (150μg/ml) and S.C. (250μg/ml) were 89.6% and 69.5% respectively.

  4. Pulse Radiolysis Using Very-high-energy Ions for Optimizing Cancer Therapy.

    PubMed

    Getoff, Nikola

    2016-01-01

    Cancer therapy by means of high-energy ions is very efficient. As a consequence of the linear-energy-transfer effect only a negligible part of the produced free radicals can escape combination processes to form molecular products and to cause undesired side processes. Positrons (e⁺) and γ-rays, generated by the nuclear interaction of high-energy ions in the medium, serve in monitoring the radiation dose absorbed by the tumor. However, due to the dipole nature of water molecules a small proportion of thermalized positrons (e⁺th) can become solvated (e⁺aq). Hence, they are stabilized, live longer and can initiate side reactions. In addition, positronium (Ps), besides solvated electrons (e⁺aq), can be generated and involved in the reaction mechanisms. For a better understanding of the reaction mechanisms involved and to improve cancer therapy, a time-resolved pulse radiolysis instrument using high-energy particles is discussed here. The proposed method is examined and recommended by CERN experts. It is planned to be realized at the MedAustron Radiation Therapy and Research Centre in Wiener Neustadt, Austria. PMID:26912822

  5. The reduction process of phytic acid silver ion system: A pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Joshi, Ravi; Mukherjee, Tulsi

    2007-05-01

    Reduction of silver ion in a silver-phytic acid (1:1 ratio) system has been studied using pulse radiolysis technique. Time-resolved transformation of the intermediates, Ag +→Ag 0→Ag 2+→Ag 32+, has been clearly observed in the reduction of silver-phytic acid (1:1) system. The effect of phytic acid on the formation and decay of initial silver clusters has been also studied. The surface plasmon absorption band of stable silver nanoparticle (410 nm) and dynamic light scattering technique has been used to characterize the nanoparticles and measure the average size ( Rav=100 nm).

  6. Pulse radiolysis system of OPU-LINAC in RIAST, Osaka Prefecture University

    NASA Astrophysics Data System (ADS)

    Kojima, Takao; Taniguchi, Ryoichi; Furuta, Masakazu; Okuda, Shuichi; Hara, Masayuki; Fujita, Shin'ichi

    2004-09-01

    Micro- to milli-second pulse radiolysis apparatus using short electron pulse form 18 MeV linear accelerator (Linac) is in-service at the Research institute for advanced science and technology (RIAST), Osaka Prefecture University. This apparatus is an effective tool, not only for investigation of primary process on radiation chemistry, but also for research of electron transfer mechanism playing an important role in chemistry and bioscience. This apparatus is composed of an 18 MeV electron linear accelerator (electron pulse duration: about 4 μs) and a transient light absorption measurement system. We introduce the outline of this system, transient absorption spectrum of thiocyanate aqueous solution as an example of measured data and future plan.

  7. Reactions of reducing and oxidizing radicals with caffeic acid:. a pulse radiolysis and theoretical study

    NASA Astrophysics Data System (ADS)

    Li, Xifeng; Cai, Zhongli; Katsumura, Yosuke; Wu, Guozhong; Muroya, Yusa

    2001-01-01

    Molecular calculations coupled with pulse radiolysis studies are performed to understand the reactions of radicals with caffeic acid. From molecular calculation, we find that e aq- and ·OH tend to form adducts with caffeic acid, while N 3rad tends to abstract H from 4-hydroxyl group in benzene ring, generating a semi-quinoid radical. Based on comparison of the heat of formation, the most favorable radical attack sites and the most stable radical structures are predicted. The calculation results suggest that the stability of the electron adducts pulse radiolysis. Molecular calculations seem to be a powerful tool to predict the stability and structures of transient radicals.

  8. Pulse radiolysis of nucleic acids and their base constituents: Bibliographies on radiation chemistry. XI

    NASA Astrophysics Data System (ADS)

    von Sonntag, Clemens; Ross, Alberta B.

    In the elucidation of the primary processes involved in the free-radical-induced damage to DNA and its subunits, pulse radiolysis proves to be one of the most powerful tools. The first studies data back to 1964. The updating review (C. v. Sonntag, Radiat. Phys. Chem. 1987, 30, 313) which precedes this compilation has placed the emphasis on the more recent developments. It has been felt that a bibliography including the earlier literature on this subject might be helpful for further reading. For this compilation the data stored by the Radiation Chemistry Data Center bibliographic database (1) through 1986 were processed using the SELECT keywords: purines, pyrimidines, nucleotides, nucleosides, nucleic acids and pulse radiolysis. The number of citations found was reduced by about one-third by eliminating privately published symposia papers, theses and papers not strictly relevant to this topic, e.g. on flavins, NADH, one-electron reduction of nitrouracil or the redox potential of isobarbituric acid. On the other hand, a few more papers known to us but not revealed by the keywords were added. The bibliography is arranged in approximately chronological order, references grouped by year of publication. Reviews are collected at the end of the bibliography in a separate section.

  9. Hydroxyl Radical Rate Constants: Comparing UV/H2O2 and Pulse Radiolysis for Environmental Pollutants

    EPA Science Inventory

    The objective of this study was to measure OH radical rates using both UV/H2O2 and pulse radiolysis techniques for 13 US EPA Contaminant Candidate List compounds (2,6- and 2,4-DNT, EPTC, prometon, linuron, diuron, dyfonate, diazinon, RDX, molinate, nitrobenz...

  10. Gamma and pulse radiolysis investigation of the reaction of desferrioxamine with superoxide anions.

    PubMed

    Sabourault, D; Ribiere, C; Nordmann, R; Houee-Levin, C; Ferradini, C

    1989-12-01

    The kinetic scheme of the reaction of desferrioxamine (DFO) with O2-. was studied using pulse and gamma-radiolysis. The rate constant k(O2-. + DFO) is equal to 1.3 +/- 0.1 x 10(6) dm3 mol-1s-1 at pH 7.4. Studying the competition between DFO and ferricytochrome-c for O2-. generated by gamma-radiolysis, we observed that the nitroxide free radical resulting from the reaction of O2-. with DFO and the product(s) resulting from the decay of this nitroxide radical act inversely towards the cytochrome-c-Fe3+/cytochrome-c-Fe2+ redox couple. This explains the discrepancy between our value of k(O2-. + DFO) and the one measured previously using ferricytochrome-c for the detection of O2-. The reported results show that DFO acts as a powerful O2-. scavenger, and that the products resulting from the reaction of DFO with O2-. can initiate oxidative and/or reductive reactions that should be taken into account in interpreting the effects of DFO in vitro and in vivo. PMID:2574220

  11. Electron processes in AOT reverse micelles. Part 2. Influence of oil phase. Pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Gebicki, J. L.; Bednarek, P.

    2000-11-01

    Reverse micellar systems formed of AOT, i.e. sodium bis(2-ethyl-1-hexyl) sulfo-succinate, in different hydrocarbons, without water, dry micelles, and in the presence of water, wet micelles, have been studied by means of pulse radiolysis. Different localization sites of hydrated electron within wet reverse micelle including a triad e aq-/Na +/SO 3- rad (absorption band peaking around 610 nm) are proposed and discussed to explain the influence of the ratio [water]/[AOT] and of the kind of alkane on the position and half-width of the absorption spectrum of the hydrated electron. Sulfite radical, necessary to form such triad, is released as a result of electron interaction with AOT molecule within reverse micelles (RM) containing water. A product of direct electron attachment to AOT molecule, AOT radical anion, has been observed spectrophotometrically only in dry AOT RM at ambient temperature (absorption band peaking around 330 nm).

  12. Pulse radiolysis of malachite green leucocyanide in alcoholic solvents, the influence of oxygen

    NASA Astrophysics Data System (ADS)

    Grodkowski, J.; Stuglik, Z.; Wieczorek, G.

    The solutions of malachite green leucocyanide (MGCN) in methanol, n-propanol and 2-propanol were investigated using pulse radiolysis. In the presence of oxygen, MG +-carbonium ions were radiolytically formed in two different time steps. The yield of MG + in the slower process was dependent on oxygen concentration and was proportional to the yield of intermediate MG · radicals. The yield of MG · was about ten times higher in 2-propanol than in methanol and n-propanol solutions. The reactants responsible for MG · oxidation to MG + were RO ·2, hydroxyalkylperoxyl radicals derived from alcohols. The rate constant for MG · reaction with RO ·2 were estimated as (6.5±1) × 10 8 M -1 s -1. The molar extinction coefficient of MG · was calculated as ɛ (400 nm) = (8.5±1) × 10 4 M -1 cm -1.

  13. Pulse and gamma radiolysis studies of 3-sulfo propyl methacrylate in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Panda, Anjali; Mohan, Hari; Sabharwal, S.

    2001-10-01

    Radiation induced polymerization of 3-sulfo propyl methacrylate (SPMA) in aqueous solution (10 wt%) has been studied by steady state and pulse radiolysis techniques. The effect of radiation characteristics such as irradiation dose, dose rate and the presence of crosslinking agent on the gel formation of SPMA monomer has been investigated. In N 2 -saturated solution, the gel formation doses for SPMA were found to be 70 and 258 Gy at dose rates of 1.2 and 5 kGy h -1, respectively. The swelling ratio results showed that the gel obtained at a constant dose of 0.8 kGy dose swells ˜630 times of its dry weight at a dose rate of 5 kGy h -1 whereas it is 394 times of its dry weight for the dose rate 1.2 kGy h -1. The reactions of the primary radicals of water radiolysis such as e aq-, H-atom, OH radical, O rad - , and some oxidizing radicals like N3rad , Cl2rad - , SO4rad - and reducing species like CO 2rad - with SPMA have been studied using pulse radiolysis technique. The results show that the reaction of e aq-, H-atom and OH radicals with SPMA are in the diffusion controlled limit with their respective bimolecular rate constant values being 8.6×10 9, 2×10 9 and 1.5×10 10 dm 3 mol -1 s -1. The radical anion, SPMA rad - , ( λmax=280 nm) is observed to undergo fast protonation forming H-adduct, SPMA—H rad , ( λmax=310 nm) with a p Ka value of 9.1. Cl 2rad - reacts with a bimolecular rate constant of 3.5×10 7 dm 3 mol -1 s -1 forming solute radical cation ( λmax=265 nm). One-electron oxidation and reduction potentials for SPMA/SPMA rad + and SPMA/SPMA rad - couples are estimated to be more than +1.6 and less than -1.9 V, respectively.

  14. Oxidation reactions of 2-thiouracil: a theoretical and pulse radiolysis study.

    PubMed

    Prasanthkumar, K P; Suresh, C H; Aravindakumar, C T

    2012-11-01

    The reaction of hydroxyl radical ((•)OH) with the nucleic acid base analogue 2-thiouracil (1) has been studied by pulse radiolysis experiments and DFT. The generic intermediate radicals feasible for the (•)OH reactions with 1, namely, one electron oxidation product (1(•+)), (•)OH-adducts (3(•), 4(•), and 5(•)), and H-abstracted radicals (6(•) and 7(•)), were characterized by interpreting their electronic and structural properties along with calculated energetics and UV-vis spectra. Pulse radiolysis experiments showed that the transient formed in the reaction of (•)OH with 1 in water at pH 6.5 has λ(max) at 430 nm. A bimolecular rate constant, k(2) of 9.6 × 10(9) M(-1) s(-1), is determined for this reaction via competition kinetics with 2-propanol. The experiments suggested that the transient species could be a dimer radical cation 2(•+), formed by the reaction of 1 with the radical cation 1(•+). For this reaction, an equilibrium constant of 4.7 × 10(3) M(-1) was determined. The transient formed in the reaction of 1 with pulse radiolytically produced Br(2)(•-) at pH 6.5 as well as Cl(2)(•-) at pH 1 has also produced λ(max) at 430 nm and suggested the formation of 2(•+). The calculated UV-vis spectra of the transient species (1(•+), 3(•), 4(•), 5(•), 6(•), and 7(•)) showed no resemblance to the experimental spectra, while that of 2(•+) (λ(max) = 420 nm) agreed well with the experimental value and thus confirmed the formation of 2(•+). The 420 nm peak was due to σ → σ* electronic excitation centered on a 2-center-3-electron (2c-3e) sulfur-sulfur bond [-S∴S-]. 2(•+) is the first reported example of a dimer radical cation in a pyrimidine heterocyclic system. Further, 5-C and 6-C substituted (substituents are -F, -Cl, -NH(2), -N(CH(3))(2), -OCH(3), -CF(3), -CH(3), -CH(2)CH(3), n-propyl, phenyl, and benzyl) and 5,6-disubstituted 2-thiouracil systems have been characterized by DFT and found that the reaction (1 + 1

  15. Pulse radiolysis studies on the polymerization of 1,6-hexanediol diacrylate in cyclohexane solvent

    NASA Astrophysics Data System (ADS)

    Wojnárovits, L.; Takács, E.; Dobó, J.; Földiák, G.

    The mechanism of initiation and kinetics of radiation induced polymerization of 1,6-hexanediol diacrylate (HDDA) was studied by pulse radiolysis with optical detection in cyclohexane solution and in pure HDDA at room temperature. In both cases a transient light absorption decreasing with the wavelength in the 270-400 nm wavelength range, but possessing a shoulder at 310 nm was observed. The spectrum did not change with time after the pulse. The absorption is due to α-carboxyalkyl radicals: the assignment was supported by the results obtained from the reaction of electrons with methyl 2-chloropropionate leading to dechlorination. The radicals produced from HDDA or from the chloro compound decayed in a second order process with rate parameters of 5 · 10 8 and of 4 · 10 9 mol -1 dm 3 s -1 in cyclohexane. In the presence of oxygen the corresponding peroxy radicals decaying in very slow process (several milliseconds) were observed. The results are interrupted in terms of radical polymerization mechanism.

  16. Oxidation processes of aromatic sulfides by hydroxyl radicals in colloidal solution of TiO 2 during pulse radiolysis

    NASA Astrophysics Data System (ADS)

    Tojo, Sachiko; Tachikawa, Takashi; Fujitsuka, Mamoru; Majima, Tetsuro

    2004-01-01

    The pulse radiolysis technique has been used to elucidate the oxidation reaction of aromatic sulfides by hydroxyl radicals on the TiO 2 nanoparticles in pH 2 aqueous solution. The hydroxyl radicals generated during the pulse radiolysis of the colloidal TiO 2 aqueous solution were strongly adsorbed on the TiO 2 particles with an apparent association constant ( Kapp) of ˜10 6 M -1. The hydroxyl radicals trapped on the TiO 2 surface exhibit the absorption spectrum with a maximum peak at 370 nm. In order to clear the oxidative ability of this species, the oxidation processes of 4-methylthiophenylmethanol (MTPM) and 2-phenylthioethanol (PTE) in the colloidal TiO 2 aqueous solution have been examined based on the kinetic analysis of the transient absorption.

  17. Optical absorption spectra and kinetics of transients of phenolic stabilizers in n-hexadecane; A pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Brede, O.

    By means of pulse radiolysis experiments the formation of transients derived from differently structured phenolic stabilizers such as 2,6-di-tert-butyl-4-methylphenol, n-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate and bis-(2-hydroxy-3-tert-butyl-5-methylphenyl)sulfide and one of its isomers in n-hexadecane solution was analyzed. Some phenoxyl and cyclohexadienyl type radicals, anions and their subsequent radical products are identified and characterized kinetically.

  18. Pulse radiolysis of supercritical water I. Ractions between hydrophobic and anionic species.

    SciTech Connect

    Cline, J.; Takahashi, K.; Marin, T. W.; Jonah, C. D.; Bartels, D. M.; Chemistry

    2002-12-26

    Reaction rates of solvated electrons with oxygen and with sulfur hexafluoride were measured in hydrothermal and supercritical water using transient absorption spectroscopy and electron pulse radiolysis. Under alkaline conditions, the reaction of hydrogen atoms with hydroxide ions to generate solvated electrons was also observed in the presence of the SF{sub 6} scavenger. At temperatures below 300 C, the rate constants for scavenging by O{sub 2} or SF{sub 6} follow Arrhenius behavior but become increasingly dependent on water density (pressure) at higher temperatures. Above 100 C, the rate constant for the H reaction with OH- falls well below the numbers extrapolated from the Arrhenius behavior in the one atmosphere liquid. At a fixed temperature above the water critical temperature (380 C, T/T{sub c}=1.01), rate constants for all three reactions reach a distinct minimum near 0.45 g/cm3. We propose an explanation for this behavior in terms of the potential of mean force separating an ion (OH- or (e-)aq) from a hydrophobic species (H, O{sub 2}, or SF{sub 6}) in the compressible fluid. The data also reveal an increasing initial yield of atomic hydrogen relative to solvated electrons as water density decreases. The initial yield of H appears to surpass that of solvated electrons when the water density is below 0.6 g/cm3 at 380 C.

  19. Photophysical properties of gatifloxacin in aqueous solution by laser flash photolysis and pulse radiolysis

    NASA Astrophysics Data System (ADS)

    Li, Haixia; Zhang, Peng; Liu, Yancheng; Tang, Ruizhi; Xing, Zhaoguo; Yao, Side; Fu, Haiying; Wang, Wenfeng

    2012-01-01

    GFX in water, at pH 7.0, shows intense absorption bands with peaks at 284 and 333 nm, ( ɛ=24,670 and 12,670 M -1 cm -1). Both the absorption and emission properties of GFX were pH-dependent; the p Ka values for the protonation equilibria of the ground state (5.7 and 8.9) and excited singlet state (3.6 and 7.5) of GFX were determined spectroscopically. GFX fluoresces weakly, with a maximum quantum yield for fluorescence emission (0.06) at pH 4.7. A series of experiments were performed to characterize the transient species of GFX in aqueous solution using laser flash photolysis and pulse radiolysis. GFX undergoes monophotonic photoionization with a quantum yield of 0.16 on a 355 nm laser excitation. This process leads to the formation of a long-lived cation radical with a maximum absorption at 380 nm. Triplet-triplet absorption had maximum absorption at 510 nm. The reaction of GFX with one-electron oxidant N3• was investigated and the bimolecular rate constant was determined to be 3.1×10 9 M -1 s -1.

  20. Photoreduction of azaoxoisoaporphines by amines: laser flash and steady-state photolysis and pulse radiolysis studies.

    PubMed

    de la Fuente, Julio R; Aliaga, Christian; Cañete, Alvaro; Kciuk, Gabriel; Szreder, Tomasz; Bobrowski, Krzysztof

    2013-01-01

    Photoreduction of 7H-benzo[e]perimidin-7-one (3-AOIA, A1) and its 2-methyl derivative (2-Me-3-AOIA, A2) by non-H-donating amines (1,4-diazabicyclo[2.2.2]octane [DABCO]; 2,2,6,6-tetramethylpiperidine [TMP]), and a hydrogen-donating amine (triethylamine [TEA]), has been studied in deaerated neat acetonitrile solutions using laser flash photolysis (LFP) and steady-state photolysis. The triplet excited states of A1 and A2 were characterized by a strong absorption band with λmax = 440 nm and lifetimes of 20 and 27 μs respectively. In the presence of tertiary amines, both triplet excited states were quenched with rate constants close to the diffusional limit (kq ranged between 10(9) and 10(10) M(-1) s(-1)). The transient absorption spectra observed after quenching with DABCO and TMP were characterized by maxima located at 460 nm and broad shoulders in the range of 500-600 nm. These transient species are attributed to solvent-separated radical ion pairs and/or to isolated radical anions. In the presence of TEA, these transients undergo proton transfer, leading to the neutral hydrogenated radicals, protonated over the N1- and O-atoms. Transient absorption spectra of these transients were characterized by maxima located at 400 and 520 nm and 430 nm respectively. Additional support for these spectral assignments was provided by pulse radiolysis (PR) experiments in acetonitrile and 2-propanol solutions. PMID:23647175

  1. Mechanism of oxidative conversion of Amplex® Red to resorufin: Pulse radiolysis and enzymatic studies.

    PubMed

    Dębski, Dawid; Smulik, Renata; Zielonka, Jacek; Michałowski, Bartosz; Jakubowska, Małgorzata; Dębowska, Karolina; Adamus, Jan; Marcinek, Andrzej; Kalyanaraman, Balaraman; Sikora, Adam

    2016-06-01

    Amplex® Red (10-acetyl-3,7-dihydroxyphenoxazine) is a fluorogenic probe widely used to detect and quantify hydrogen peroxide in biological systems. Detection of hydrogen peroxide is based on peroxidase-catalyzed oxidation of Amplex® Red to resorufin. In this study we investigated the mechanism of one-electron oxidation of Amplex® Red and we present the spectroscopic characterization of transient species formed upon the oxidation. Oxidation process has been studied by a pulse radiolysis technique with one-electron oxidants (N3(•), CO3(•-),(•)NO2 and GS(•)). The rate constants for the Amplex® Red oxidation by N3(•) ((2)k=2.1·10(9)M(-1)s(-1), at pH=7.2) and CO3(•-) ((2)k=7.6·10(8)M(-1)s(-1), at pH=10.3) were determined. Two intermediates formed during the conversion of Amplex® Red into resorufin have been characterized. Based on the results obtained, the mechanism of transformation of Amplex® Red into resorufin, involving disproportionation of the Amplex® Red-derived radical species, has been proposed. The results indicate that peroxynitrite-derived radicals, but not peroxynitrite itself, are capable to oxidize Amplex® Red to resorufin. We also demonstrate that horseradish peroxidase can catalyze oxidation of Amplex® Red not only by hydrogen peroxide, but also by peroxynitrite, which needs to be considered when employing the probe for hydrogen peroxide detection. PMID:27021961

  2. Pulse radiolysis studies of 3,5-dimethyl pyrazole derivatives of selenoethers.

    PubMed

    Barik, Atanu; Singh, Beena G; Sharma, Asmita; Jain, Vimal K; Priyadarsini, K Indira

    2014-11-01

    One electron redox reaction of two asymmetric 3,5-dimethyl pyrazole derivatives of selenoethers attached to ethanoic acid (DPSeEA) and propionic acid (DPSePA) were studied by pulse radiolysis technique using transient absorption detection. The reaction of the hydroxyl ((•)OH) radical with DPSeEA or DPSePA at pH 7 produced transients absorbing at 500 nm and at 300 nm, respectively. The absorbance at 500 nm increased with increasing parent concentration indicating formation of dimer radical cations. From the absorbance changes, the equilibrium constants for the formation of dimer radical cation of DPSeEA and DPSePA were estimated as 2020 and 1608 M(-1), respectively. The rate constants at pH 7 for the reaction of the (•)OH radical with DPSeEA and DPSePA were determined to be 9.6 × 10(9) and 1.4 × 10(10) M(-1) s(-1), respectively. The dimer radical cation of DPSeEA and DPSePA decayed by first order kinetics with a rate constant of 2.8 × 10(4) and 5.5 × 10(3) s(-1), respectively. The yield of radical cations of DPSeEA and DPSePA were estimated from the secondary electron transfer reaction, which corresponds to 38% and 48% of (•)OH radical yield, respectively. Some fraction of monomer radical cation undergoes decarboxylation reaction, and the yield of decarboxylation was 25% and 20% for DPSeEA and DPSePA, respectively. These results have implication in understanding their antioxidant activity. The reaction of trichloromethyl peroxyl radical, glutathione, and ascorbic acid further support their antioxidant behavior. PMID:25342303

  3. One-electron redox processes in a cyclic selenide and a selenoxide: a pulse radiolysis study.

    PubMed

    Singh, Beena G; Thomas, Elizabeth; Kumakura, Fumio; Dedachi, Kenichi; Iwaoka, Michio; Priyadarsini, K Indira

    2010-08-19

    One-electron redox reactions of cyclic selenium compounds, DL-trans-3,4-dihydroxy-1-selenolane (DHS(red)), and DL-trans-3,4-dihydroxy-1-selenolane oxide (DHS(ox)) were carried out in aqueous solutions using nanosecond pulse radiolysis, and the resultant transients were detected by absorption spectroscopy. Both *OH radical and specific one-electron oxidant, Br(2)(*-) radical reacted with DHS(red) to form similar transients absorbing at 480 nm, which has been identified as a dimer radical cation (DHS(red))(2)(*+). Secondary electron transfer reactions of the (DHS(red))(2)(*+) were studied with 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS(2-)) and superoxide (O(2)(*-)) radicals. The bimolecular rate constants for the electron transfer reaction between (DHS(red))(2)(*+) with ABTS(2-) was determined as 2.4 +/- 0.4 x 10(9) M(-1) s(-1). From this reaction, the yield of (DHS(red))(2)(*+) formed on reaction with *OH radical was estimated in the presence of varying phosphate concentrations. (DHS(red))(2)(*+) reacted with O(2)(*-) radical with a bimolecular rate constant of 2.7 +/- 0.1 x 10(9) M(-1) s(-1) at pH 7. From the same reaction, the positive charge on (DHS(red))(2)(*+) was confirmed by the kinetic salt effect. HPLC analysis of the products formed in the reaction of (DHS(red))(2)(*+) with O(2)(*-) radicals showed formation of the selenoxide, DHS(ox). In order to know if a similar mechanism operated during the reduction of DHS(ox), its reactions with e(aq)(-) were studied at pH 7. The rate constant for this reaction was determined as 5.6 +/- 0.9 x 10(9) M(-1) s(-1), and no transient absorption could be observed in the wavelength region from 280 to 700 nm. It is proposed that the radical anion (DHS(ox))(*-) formed by a one-electron reduction would get protonated to form a hydroxyl radical adduct, which in presence of proton donors, would undergo dehydration to form DHS(*+). Evidence for this mechanism was obtained by converting DHS(*+) to (DHS(red))(2

  4. Laser pulse stacking method

    DOEpatents

    Moses, Edward I.

    1992-01-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter.

  5. Laser pulse stacking method

    DOEpatents

    Moses, E.I.

    1992-12-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

  6. Vitamin E analogue Trolox C. E.s.r. and pulse-radiolysis studies of free-radical reactions.

    PubMed Central

    Davies, M J; Forni, L G; Willson, R L

    1988-01-01

    The reactions between Trolox C, a water-soluble vitamin E analogue, and several oxidizing free radicals including the hydroxyl radical and various peroxy radicals were examined by using the pulse-radiolysis technique. The results demonstrate that Trolox C may undergo rapid one-electron-transfer reactions as well as hydrogen-transfer processes; the resulting phenoxyl radical is shown to be relatively stable, in common with the phenoxyl radical derived from vitamin E. The reactions between the Trolox C phenoxyl radical and a variety of biologically relevant reducing compounds were examined by using both pulse radiolysis and e.s.r. The results demonstrate that the Trolox C phenoxyl radical is readily repaired by ascorbate (k = 8.3 x 10(6) dm3.mol-1.s-1) and certain thiols (k less than 10(5) dm3.mol-1.s-1) but not by urate, NADH or propyl gallate. Evidence from e.s.r. studies indicates that thiol-containing compounds may also enter into similar repair reactions with the alpha-tocopherol phenoxyl radical. Kinetic evidence is presented that suggests that Trolox C may 'repair' proteins that have been oxidized by free radicals. PMID:2849418

  7. The oxidation of phenol by ferrate(VI) and ferrate(V). A pulse radiolysis and stopped-flow study.

    PubMed

    Rush, J D; Cyr, J E; Zhao, Z; Bielski, B H

    1995-04-01

    Potassium ferrate, K2FeO4, is found to oxidize phenol in aqueous solution (5.5 < or = pH < or = 10) by a process which is second order in both reactants; -d[FeVI]/dt=k1[FeVI][phenol], k1 = 10(7)M-1s-1. Product analysis by HPLC showed a mixture of hydroxylated products, principally paraquinone, and biphenols that indicate that oxidation of phenol occurs by both one-electron and two-electron pathways. The two-electron oxidant, producing both para- and ortho-hydroxylated phenols is considered to be ferrate(V) which is itself produced by the initial one-electron reduction of ferrate(VI). The rate of ferrate(V) reaction with phenol was determined by pre-mix stopped flow pulse-radiolysis and found to be k7 = (3.8 +/- 0.4) x 10(5)M-1s-1. PMID:7633565

  8. Local density augmentation of supercritical water probed by 4,4‧-bpyHrad radical: A pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Liu, Zhe; Fang, Zhong; Muroya, Yusa; Fu, Haiying; Yan, Yu; Katsumura, Yosuke; Lin, Mingzhang

    2016-07-01

    Solvatochromic shift of 4,4‧-bpyHrad in aqueous solutions at elevated temperatures up to supercritical conditions and in various organic solvents with different dielectric constants, is investigated by pulse-radiolysis technique. 4,4‧-bpyHrad shows a stronger solvent-solute interaction in water than in organic solvents, perhaps due to the hydrogen bond between 4,4‧-bpyHrad and water. At 380 °C, local density augmentation, namely ρlocal-ρbulk, in supercritical water becomes 280 kg m-3 (ρbulk = 208 kg m-3), and the density enhancement factor is 8.9. Density fluctuation maximizes when ρbulk is around 120 kg m-3. Density inhomogeneity decreases as temperature rises, but is still remarkable at 400 °C.

  9. Synthesis, pulse radiolysis, and in vitro radioprotection studies of melatoninolipoamide, a novel conjugate of melatonin and alpha-lipoic acid.

    PubMed

    Venkatachalam, S R; Salaskar, A; Chattopadhyay, A; Barik, A; Mishra, B; Gangabhagirathi, R; Priyadarsini, K I

    2006-09-15

    A novel conjugate of melatonin 2 and alpha-lipoic acid 4 has been prepared using DCC mediated coupling. The conjugate named melatoninolipoamide has been assigned its structure 1 on the basis of spectral analysis (UV, IR, NMR, and EI-MS). Pulse radiolysis studies of the conjugate were carried out in aqueous solutions with both oxidizing and reducing radicals. The results indicate that the melatonin moiety of the conjugate reacts preferably with oxidizing radicals and the lipoic acid moiety exhibits preferential reaction with reducing radicals. The in vitro radioprotection ability of 1 was examined by gamma-radiation induced lipid peroxidation in liposomes and hemolysis of erythrocytes, and compared the results with those of melatonin and alpha-lipoic acid. The studies suggest that the conjugate can be explored as a probable radioprotector. PMID:16766192

  10. Mechanism of benzophenone ketyl radical formation in acid alcohols studied by pulse-radiolysis and rigid-matrix techniques. [Gamma rays

    SciTech Connect

    Hoshino, M.; Arai, S.; Imamura, M.; Ikehara, K.; Hama, Y.

    1980-10-02

    The mechanism of the benzophenone ketyl radical formation in acid methanol, ethanol, and 2-propanol was studied by using pulse-radiolysis and rigid-matrix techniques. When a 0.1 M ethanol solution of benzophenone containing hydrogen chloride (1.2 M) was irradiated at 77 K by ..gamma.. rays from /sup 60/Co, the absorption spectrum of the trapped intermediates was ascribed solely to benzophenone ketyl radicals. The pulse-radiolysis study of the solution at 100 K revealed that the ketyl radicals are produced by protonation of presolvated benzophenone anion radicals. At 153 K, the ketyl radicals were observed to be produced also by hydrogen-atom transfer from CH/sub 3/CHOH and CH/sub 3/CH(OH)CH/sub 3/ to benzophenone; the temperature dependence of the transfer rate constant was studied.

  11. Examination of the formation process of pre-solvated and solvated electron in n-alcohol using femtosecond pulse radiolysis

    NASA Astrophysics Data System (ADS)

    Toigawa, Tomohiro; Gohdo, Masao; Norizawa, Kimihiro; Kondoh, Takafumi; Kan, Koichi; Yang, Jinfeng; Yoshida, Yoichi

    2016-06-01

    The formation process of pre-solvated and solvated electron in methanol (MeOH), ethanol (EtOH), n-butanol (BuOH), and n-octanol (OcOH) were investigated using a fs-pulse radiolysis technique by observing the pre-solvated electron at 1400 nm. The formation time constants of the pre-solvated electrons were determined to be 1.2, 2.2, 3.1, and 6.3 ps for MeOH, EtOH, BuOH, and OcOH, respectively. The formation time constants of the solvated electrons were determined to be 6.7, 13.6, 22.2, and 32.9 ps for MeOH, EtOH, BuOH, and OcOH, respectively. The formation dynamics and structure of the pre-solvated and solvated electrons in n-alcohols were discussed based on relation between the obtained time constant and dielectric relaxation time constant from the view point of kinetics. The observed formation time constants of the solvated electrons seemed to be strongly correlated with the second component of the dielectric relaxation time constants, which are related to single molecule motion. On the other hand, the observed formation time constants of the pre-solvated electrons seemed to be strongly correlated with the third component of the dielectric relaxation time constants, which are related to dynamics of hydrogen bonds.

  12. Pulse radiolysis and 77 K matrix. gamma. irradiation of dimethyl truxinates and trans-methyl cinnamate in 2-methyltetrahydrofuran

    SciTech Connect

    Takamuku, S.; Kigawa, H.; Suematsu, H.; Susumu, T.; Tsumori, K.; Sakurai, H.

    1982-05-13

    One-electron reduction of dimethyl ..mu..-truxinate (..mu..-DMT), dimethyl ..beta..-truxinate (..beta..-DMT), and dimethyl ..cap alpha..-truxillate (..cap alpha..-DMT) has been investigated by pulse radiolysis and 77 K matrix ..gamma.. irradiation of the 2-methyltetrahydrofuran solutions. Cycloreversion of the radical anions formed by an electron attachment to these cyclobutanes was observed in all cases, even at 77 K. The orientation of the cycloreversion was dependent on the stereochemistry of the cyclobutanes, and the selectivity was reasonably explained by a so-called cis effect; the best possible release of steric hindrance decides the primary step of the reaction. In 77 K matrix ..gamma.. irradiation of ..cap alpha..-DMT, an intense IR absorption was found after the photobleaching of trapped electrons with light > 690 nm. In other DMTs, the IR absorption band was not observed while the cycloreversion of DMT by mobile electrons occurred. Thus, the IR band in the case of ..cap alpha..-DMT was assigned to an associated dimer anion due to the interaction between the radical anion and the neutral molecule pair of trans-methyl cinnamate orginally formed by the cycloreversion of ..cap alpha..-DMT. The dimer anion was presumed to be oriented in a head-to-tail structure in a solvent cage on the basis of the original configuration of ..cap alpha..-DMT.

  13. Design of a high pressure system for pulse radiolysis studies up to 400 MPa with flow regulation

    NASA Astrophysics Data System (ADS)

    NGuyen Le, D.-T.; Pin, S.; Anjoure, D.; Chopineau, P.; Baldacchino, G.

    2013-03-01

    This article reports details of a new setup including an optical flow cell and devices which can increase pressure up to 400 MPa by controlling the ramp rate. It is composed of two high pressure syringe pumps which can make liquids flowing up to 4 cm3/mn. The optical flow cell can contains aqueous solutions and allow carry out pulse radiolysis experiments with a pulsed 10-MeV electron beam by performing in situ and time resolved optical analysis, such as transient UV-visible absorption or fluorescence spectroscopy. A Labview-program has been developed to drive and monitor automatons which regulate pressure, make solution flow under pressure, carry out operations such as filling, emptying or cleaning the system under safe conditions. Two results are exhibited: 1/associated to phosphate buffer, the fluorescence spectrum of the fluorescein pH-sensor has been performed under pressure. Phosphate pKa is confirmed to be very sensitive to pressure increase even up to 300 MPa. 2/a time-resolved absorption spectroscopy of hydrated electron in deaerated water has been conducted up to 350 MPa with a continuous flow of sample. In presence of tertio-butanol and bisTris pH7-buffer in solution, the spectral shift of hydrated electron is finely reproduced. BisTris is also confirmed as insensitive buffer under high pressure and its reduction by hydrated electron remains constant with a rate constant of (4.6 ± 0.6) × 108 M-1 s-1.

  14. Pulse measurement apparatus and method

    DOEpatents

    Marciante, John R.; Donaldson, William R.; Roides, Richard G.

    2011-10-25

    An embodiment of the invention is directed to a pulse measuring system that measures a characteristic of an input pulse under test, particularly the pulse shape of a single-shot, nano-second duration, high shape-contrast optical or electrical pulse. An exemplary system includes a multi-stage, passive pulse replicator, wherein each successive stage introduces a fixed time delay to the input pulse under test, a repetitively-gated electronic sampling apparatus that acquires the pulse train including an entire waveform of each replica pulse, a processor that temporally aligns the replicated pulses, and an averager that temporally averages the replicated pulses to generate the pulse shape of the pulse under test. An embodiment of the invention is directed to a method for measuring an optical or an electrical pulse shape. The method includes the steps of passively replicating the pulse under test with a known time delay, temporally stacking the pulses, and temporally averaging the stacked pulses. An embodiment of the invention is directed to a method for increasing the dynamic range of a pulse measurement by a repetitively-gated electronic sampling device having a rated dynamic range capability, beyond the rated dynamic range of the sampling device; e.g., enhancing the dynamic range of an oscilloscope. The embodied technique can improve the SNR from about 300:1 to 1000:1. A dynamic range enhancement of four to seven bits may be achieved.

  15. Time-resolved resonance Raman observation of tetrafluoro-p-benzosemiquinone anion radical. [Pulse radiolysis

    SciTech Connect

    Tripathi, G.N.R.; Schuler, R.H.

    1983-08-04

    Time-resolved resonance Raman spectroscopy has been used to examine tetrafluoro-p-benzosemiquinone radical anion produced in the pulse radiolytic oxidation of tetrafluorohydroquinone in aqueous solution. This radical is much more reactive than p-benzosemiquinone and is observed to decay on the millisecond time scale in both Raman and pulse radiolytic experiments. For the Raman experiments excitation was on the red edge of the moderately strong absorption band of this radical at 430 nm. Two resonance-enhanced Raman bands are exhibited at 1556 and 1677 cm/sup -1/ and are assigned to the in-phase CO and symmetrical CC stretch vibrations. These frequencies are considerably higher than the corresponding values of 1435 and 1620 cm/sup -1/ observed in this radical's protonated counterpart. The relatively large increase in the CO stretch frequency, in particular, indicates that fluorination induces a substantial increase in the quinoid character of this radical. 3 figures, 1 table.

  16. Picosecond Pulse Radiolysis of Propylene Carbonate as a Solute in Water and as a Solvent.

    PubMed

    Marignier, Jean-Louis; Torche, Fayçal; Le Caër, Sophie; Mostafavi, Mehran; Belloni, Jacqueline

    2016-03-10

    The ester propylene carbonate (PC) is a solvent with a high static dielectric constant where the charges generated by ionizing radiation are expected to be long-lived at room temperature. Time-resolved optical absorption spectroscopy after picosecond electron pulses reveals the formation of a UV band, within less than two nanoseconds, that is assigned to the radical anion PC(-•), arising from a fast attachment reaction of electrons onto PC. Assignment and reactivity of PC(-•) in neat solvent and solutions are discussed in relation with data obtained in solutions of PC in water under reducing or oxidizing conditions and in solutions in PC of aromatic scavengers with various reduction potentials. The fate of the electrons and the ionization yield in PC are compared with those of other solvents. PMID:26840402

  17. Dynamics of radical cations of poly(4-hydroxystyrene) in the presence and absence of triphenylsulfonium triflate as determined by pulse radiolysis of its highly concentrated solution

    NASA Astrophysics Data System (ADS)

    Okamoto, Kazumasa; Ishida, Takuya; Yamamoto, Hiroki; Kozawa, Takahiro; Fujiyoshi, Ryoko; Umegaki, Kikuo

    2016-07-01

    Pulse radiolysis of highly concentrated poly(4-hydroxystyrene) (PHS) solutions in cyclohexanone and p-dioxane was performed both with and without an onium-type photoacid generator (PAG). With increasing PHS concentration, the rate constant of deprotonation of PHS radical cations was found to decrease. In the presence of PAG, the yield of the multimer radical cation of PHS was shown to decrease. We found that pairing between the anions produced by the attachment of dissociative electrons of PAGs and the monomer PHS radical cations restrict local molecular motions, leading to the formation of the multimer PHS radical cations.

  18. Measuring hydrogen peroxide due to water radiolysis using a modified horseradish peroxidase based biosensor as an alternative dosimetry method.

    PubMed

    Tavakoli, Hassan; Baghbanan, Amin Azam

    2015-08-01

    H2O2 generated during water radiolysis was measured electrochemically as an alternative dosimetry method. A biosensor was fabricated by immobilising modified horseradish peroxidase (HRP) on a glassy carbon electrode (GCE) followed by evaluation of its analytical parameters. Anthraquinone 2-carboxylic acid was used to modify HRP. To assess sensor performance, phosphate buffer solutions were irradiated with 0.510 Gy of gamma ray emitted from (60)Co. The results showed that this sensor can detect low quantities of hydrogen peroxide in water radiolysis. Sensitivity, detection limit and linear range of the biosensor were 260 nA/Gy, 0.392 Gy and 0.5-5 Gy, respectively. Long term stability studies showed that sensor responses were stable for at least a month. The cathodic peak current, as biosensor response, subsequently decreased to 20% of its initial value. PMID:25880374

  19. One-electron reduction of iron(II) porphyrin and characterization of iron(I) porphyrin in aqueous medium. Steady-state and pulse radiolysis studies. [Gamma radiation

    SciTech Connect

    Brault, D.; Santus, R.; Land, E.J.; Swallow, A.J.

    1984-11-22

    Iron(II) deuteroporphyrin reacts with the reducing (CH/sub 3/)/sub 2/CO/sup -/ radicals produced by radiolysis of deoxygenated alkaline aqueous 2-propanol solutions with rate constant of (6.3 +/- 0.3) x 10/sup 8/ M/sup -1/ s/sup -1/. The product has the same optical spectrum whether obtained from steady-state or pulse irradiation. It reoxidizes slowly even in the absence of oxygen to the ferrous state with a rate constant of (1.35 +/- 0.15) x 10/sup -3/ s/sup -1/. Water is suggested as the oxidizing agent. When sodium dithionite is used, reoxidation is fast due to side reactions. The reoxidation of the radiolytic product to the ferric state in the presence of oxygen shows very good reversibility. The deuteroporphyrin anion radical produced by pulse radiolysis of deuteroporphyrin in the same solvent mixture is much less stable than the iron(II) deuteroporphyrin product, consistent with the view that the latter should be formulated as an iron(I) form.

  20. Laser beam pulse formatting method

    DOEpatents

    Daly, Thomas P.; Moses, Edward I.; Patterson, Ralph W.; Sawicki, Richard H.

    1994-01-01

    A method for formatting a laser beam pulse (20) using one or more delay loops (10). The delay loops (10) have a partially reflective beam splitter (12) and a plurality of highly reflective mirrors (14) arranged such that the laser beam pulse (20) enters into the delay loop (10) through the beam splitter (12) and circulates therein along a delay loop length (24) defined by the mirrors (14). As the laser beam pulse (20) circulates within the delay loop (10) a portion thereof is emitted upon each completed circuit when the laser beam pulse (20) strikes the beam splitter (12). The laser beam pulse (20) is thereby formatted into a plurality of sub-pulses (50, 52, 54 and 56). The delay loops (10) are used in combination to produce complex waveforms by combining the sub-pulses (50, 52, 54 and 56) using additive waveform synthesis.

  1. Laser beam pulse formatting method

    DOEpatents

    Daly, T.P.; Moses, E.I.; Patterson, R.W.; Sawicki, R.H.

    1994-08-09

    A method for formatting a laser beam pulse using one or more delay loops is disclosed. The delay loops have a partially reflective beam splitter and a plurality of highly reflective mirrors arranged such that the laser beam pulse enters into the delay loop through the beam splitter and circulates therein along a delay loop length defined by the mirrors. As the laser beam pulse circulates within the delay loop a portion thereof is emitted upon each completed circuit when the laser beam pulse strikes the beam splitter. The laser beam pulse is thereby formatted into a plurality of sub-pulses. The delay loops are used in combination to produce complex waveforms by combining the sub-pulses using additive waveform synthesis. 8 figs.

  2. Pulse radiolysis study of reactions OH ., H . and e -aq with spin trap C-phenyl- N-tertiary-butylnitrone

    NASA Astrophysics Data System (ADS)

    Zubarev, V. E.; Mehnert, R.; Brede, O.

    The primary products of water radiolysis OH ., H . and e -aq react with C-phenyl- N-tert-butyl-nitrone(PBN) but not in a simple spin trapping manner. OH . adds mainly to the aromatic ring yielding cyclohexadienyl type radicals, whereas e -aq in pure water forms the PBN anion via the proposed intermediate O .- and alcohol radicals and an imine in the presence of alcohols.

  3. A new approach to the study of intramolecular electron-transfer reactions of metalloproteins: Pulse radiolysis of NO[sub 2]-modified tyrosine derivatives of plastocyanin

    SciTech Connect

    Govindaraju, K.; Christensen, H.E.M.; Lloyd, E.; Tomkinson, N.P.; Sykes, A.G. ); Olsen, M. ); Salmon, G.A. )

    1993-01-06

    Single NO[sub 2]-modified derivatives of plastocyanin, with modifications at Tyr83 (spinach) and Tyr83/Tyr62 (parsley, deletions at 57 and 58), have been prepared and characterized by peptide mapping. All three products give a TyrNO[sub 2] UV-vis absorbance band at 355 nm ([epsilon] = 3,900 M[sup [minus]1] cm[sup [minus]1]) at pH < 7.5, assigned to NO[sub 2], which shifts to 428 nm on increasing the pH to > 9.0 due to acid dissociation of the phenolic group. Pulse radiolysis experiments in which the reductant CO[sub 2][sup [sm bullet][minus

  4. Quick measurement of continuous absorption spectrum in ion beam pulse radiolysis: Application of optical multi-channel detector into transient species observation

    NASA Astrophysics Data System (ADS)

    Iwamatsu, Kazuhiro; Muroya, Yusa; Yamashita, Shinichi; Kimura, Atsushi; Taguchi, Mitsumasa; Katsumura, Yosuke

    2016-02-01

    A quick measurement system of a continuous absorption spectrum covering a wide range from 200 to 950 nm was constructed by employing an optical multi-channel detector. Ion beam pulse radiolysis with 12.5 MeV/u He, 18.3 MeV/u C and 17.5 MeV/u Ne ions were performed with the measurement system. Transient absorption spectrum of (S C N) 2 • - was clearly observed in KSCN aqueous solutions within a few minutes in spite of their very small absorbance, demonstrating high sensitivity of 0.001-0.003 in absorbance in the range from 260 to 660 nm as well as short measurement time of a few minutes. Two different absorption peaks attributed to Br2 • - and Br3 - were observed simultaneously in NaBr aqueous solutions, showing powerfulness of the measurement system in overviewing chemical kinetics under ion beam irradiation especially in not well investigated chemical systems.

  5. Pulsed ultrasonic stir welding method

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.

  6. Role of radiolytically generated species in radiation induced polymerization of sodium p-styrene sulphonate (SSS) in aqueous solution: Steady state and pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Y. K.; Mohan, H.; Sabharwal, S.; Majali, A. B.

    2000-06-01

    Radiation induced polymerization of sodium p-styrene sulphonate (SSS) in aqueous solution has been investigated by steady state and pulse radiolysis techniques. Effect of dose, dose rate, monomer concentration, pH and ambient conditions on polymerization was investigated. The reactions of primary radicals of water radiolysis such as OH radical, e -aq, H atom, O rad - and some oxidizing radicals like N rad 3, Cl rad -2,Br rad -2, and reducing specie like CO rad -2 with SSS have also been investigated. SSS reacts with OH radical with a rate constant of 5.9×10 9 dm 3 mol -1s -1 at pH 6.3. The results indicate that ˜83% of OH radicals undergo electron transfer reaction resulting in a cation radical species while remaining ˜17% react via addition reaction. The hydrated electron reacts with SSS with a rate constant 1.3×10 10 dm 3 mol -1 s -1 to form an anion that undergoes fast protonation to form H-adduct at pH 6.3. At high pH (>10) the anion is able to transfer electron to methyl vilogen and p-nitro aceto phenone ( p-NAP) where as H-adduct is unable to transfer electron. At pH ˜1 H atom reaction with SSS is diffusion controlled with a rate constant of 5×10 9 dm 3 mol -1 s -1 and results in formation of H adduct. It was seen that anion reacts with solute an order faster than cation generated radiolytically indicating anionic initiation of polymerization of SSS. Molecular weight of the polymer formed by radiation polymerization, determined by viscosity measurement, are of the order of 10 7 and higher molecular weight polymers are obtained at lower dose rates. In presence of a crosslinking agent gelation of polymer is much faster than the monomer and a polymer concentration ˜20% is most efficiently crosslinked.

  7. Effect of isopropyl alcohol on the surface localization and recombination of conduction-band electrons in Degussa P25 TiO sub 2. A pulse-radiolysis time-resolved microwave conductivity study. [Accelerated electrons

    SciTech Connect

    Warman, J.M.; Hass, M.P. de ); Pichat, P. ); Serpone, N. Concordia Univ., Montreal, Quebec )

    1991-10-31

    Conduction-band electrons, formed by pulse radiolysis of Degussa P25 TiO{sub 2} particles, have been monitored by time-resolved microwave conductivity and found to undergo equilibrium localization and eventual recombination at the particle surface. In the presence of isopropyl alcohol recombination is retarded due to surface hole scavenging. The particle bulk can then be pumped with mobile electrons, which survive for seconds.

  8. Pulse radiolysis study on free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one). 2: A comparative study on edaravone derivatives.

    PubMed

    Hata, Kuniki; Lin, Mingzhang; Katsumura, Yosuke; Muroya, Yusa; Fu, Haiying; Yamashita, Shinichi; Nakagawa, Hidehiko

    2011-01-01

    A comparative study using the pulse radiolysis technique was carried out to investigate transient absorption spectra and rate constants for the reactions of (•)OH and N(3)(•) with edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) and its four analogue compounds, 1,3-dimethyl-2-pyrazolin-5-one, 3-methyl-1-(pyridin-2-yl)-2-pyrazolin-5-one, 1-phenyl-3-trifluoromethyl-2-pyrazolin-5-one and 1-(4-chlorophenyl)-3-methyl-2-pyrazolin-5-one. The results showed that, unlike reaction mechanisms previously proposed, the phenyl group of edaravone played an important role in the reaction with (•)OH and OH adducts to the phenyl group were formed. Quantum chemical calculations also strongly supported this attribution and suggested that the most favorable site for attacks by (•)OH is the ortho position of the phenyl group. Moreover, the rate constants for the reactions of edaravone and its analogues towards (•)OH and N(3)(•) were about 8.0 × 10(9), and 4.0 × 10(9) dm(3) mol(-1) s(-1), respectively. Edaravone displayed higher reactivity compared to the others, in contrast to a previous report in which 3-methyl-1-(pyridin-2-yl)-2-pyrazolin-5-one showed the highest reactivity towards (•)OH. PMID:21139328

  9. Temperature dependence of the rate constant for hydrogen atom reaction with Cl2-• in water by pulse radiolysis of aqueous HCl solution

    NASA Astrophysics Data System (ADS)

    Kazmierczak, L.; Szala-Bilnik, J.; Wolszczak, M.; Swiatla-Wojcik, D.

    2015-12-01

    The temperature dependence of the rate constant for the reaction of dichloride anion radical (Cl2-•) with atomic hydrogen (H•) in water up to 75 °C has been determined by pulse radiolysis of deaerated 0.1 M HCl solution. The room temperature value is (6.1±0.6)×109 M-1 s-1. The activation energy of (13.2±0.6) kJ mol-1 is less than 16.7 kJ mol-1, expected for the diffusion-controlled reaction. Based on the temperature dependence of the rate constant for the reactions H•+ Cl2-• and H•+Cl2, derived in this work, and on that reported earlier (Szala-Bilnik et al., 2014) for Cl2-• + Cl2SUP>-•, we show that a value of (10±2) M-1 s-1 determined by Hartig and Getoff (1982) for k (H•+H2O) in water at 25 °C is overestimated by at least two orders of magnitude.

  10. Magnetic Alignment of Pulsed Solenoids Using the Pulsed Wire Method

    SciTech Connect

    Arbelaez, D.; Madur, A.; Lipton, T.M.; Waldron, W.L.; Kwan, J.W.

    2011-04-01

    A unique application of the pulsed-wire measurement method has been implemented for alignment of 2.5 T pulsed solenoid magnets. The magnetic axis measurement has been shown to have a resolution of better than 25 {micro}m. The accuracy of the technique allows for the identification of inherent field errors due to, for example, the winding layer transitions and the current leads. The alignment system is developed for the induction accelerator NDCX-II under construction at LBNL, an upgraded Neutralized Drift Compression experiment for research on warm dense matter and heavy ion fusion. Precise alignment is essential for NDCX-II, since the ion beam has a large energy spread associated with the rapid pulse compression such that misalignments lead to corkscrew deformation of the beam and reduced intensity at focus. The ability to align the magnetic axis of the pulsed solenoids to within 100 pm of the induction cell axis has been demonstrated.

  11. A Method to Simultaneously Improve PCB Radiolysis Rates in Oil and to Close the Chlorine Mass Balance

    SciTech Connect

    Mincher, Bruce Jay; Curry, R. C.; Brey, R.

    2000-06-01

    The addition of alkaline 2-propanol to isooctane and transformer oil solutions of PCBs was found to increase the rate of PCB dechlorination by -radiolysis. Simultaneously, it facilitates the closure of the chlorine mass balance. The chlorine liberated from PCBs irradiated in alkaline 2-propanol-spiked solutions precipitated as an inorganic salt in a stoichiometric amount. This was demonstrated for an individual PCB congener (PCB 155) in isooctane and for Aroclor 1260 in transformer oil. Radiolysis rates are reported in terms of dose constants, d (kGy-1), the exponential rate constant for PCB decomposition with respect to absorbed dose. These are the highest decomposition rates yet reported for the radiolytic treatment of PCB-contaminated transformer oil.

  12. Alternative methods for degradation studies by alpha radiolysis: tributyl phosphate and CMPO

    SciTech Connect

    Pearson, J.; Nilsson, M.; Miller, G.E.

    2013-07-01

    Solvent extraction separation processes used in the recycling of used nuclear fuel are susceptible to radiolytic damage from radioactive isotopes present in used fuel. Studying the respective effects on matter of both low linear energy transfer (LET) radiation such as gamma radiation and high LET such as alpha radiation will allow for accurate prediction and modeling of process performance losses with respect to dose. The effects of gamma radiation on solvent extraction ligands have been more extensively studied than the effects of alpha radiation due to the inherent difficulty in producing a sufficient and confluent dose of alpha particles within a sample without leaving the sample contaminated with long lived radioactive isotopes. We have developed a method for studying the effects of high LET radiation in situ via {sup 10}B activation and the high LET particles that result from the {sup 10}B(n,a){sup 7}Li reaction which follows. In this study we applied this method to organic solutions of tributyl phosphate (TBP) and CMPO (compound octylphenyl-N, N-diisobutyl-carbamoyl methyl phosphine oxide) representing the PUREX and TRUEX processes respectively. Rates of degradation of TBP and CMPO and their respective degradation products in the presence of both high and low LET radiation are presented and compared to values reported in the literature. Preliminary data appears to show decreased degradation of CMPO in the presence of an aqueous acidic phase, which agrees with other studies performed on TBP solutions. (authors)

  13. Pulse-by-pulse method to characterize partially coherent pulse propagation in instantaneous nonlinear media.

    PubMed

    Lajunen, Hanna; Torres-Company, Víctor; Lancis, Jesús; Silvestre, Enrique; Andrès, Pedro

    2010-07-01

    We propose a numerical method for analyzing extensively the evolution of the coherence functions of nonstationary optical pulses in dispersive, instantaneous nonlinear Kerr media. Our approach deals with the individual propagation of samples from a properly selected ensemble that reproduces the coherence properties of the input pulsed light. In contrast to the usual strategy assuming Gaussian statistics, our numerical algorithm allows us to model the propagation of arbitrary partially coherent pulses in media with strong and instantaneous nonlinearities. PMID:20639984

  14. Radiolysis of boiling water

    NASA Astrophysics Data System (ADS)

    Yang, Shuang; Katsumura, Yosuke; Yamashita, Shinichi; Matsuura, Chihiro; Hiroishi, Daisuke; Lertnaisat, Phantira; Taguchi, Mitsumasa

    2016-06-01

    γ-radiolysis of boiling water has been investigated. The G-value of H2 evolution was found to be very sensitive to the purity of water. In high-purity water, both H2 and O2 gases were formed in the stoichiometric ratio of 2:1; a negligible amount of H2O2 remained in the liquid phase. The G-values of H2 and O2 gas evolution depend on the dose rate: lower dose rates produce larger yields. To clarify the importance of the interface between liquid and gas phase for gas evolution, the gas evolution under Ar gas bubbling was measured. A large amount of H2 was detected, similar to the radiolysis of boiling water. The evolution of gas was enhanced in a 0.5 M NaCl aqueous solution. Deterministic chemical kinetics simulation elucidated the mechanism of radiolysis in boiling water.

  15. Pulsed Electric Propulsion Thrust Stand Calibration Method

    NASA Technical Reports Server (NTRS)

    Wong, Andrea R.; Polzin, Kurt A.; Pearson, J. Boise

    2011-01-01

    The evaluation of the performance of any propulsion device requires the accurate measurement of thrust. While chemical rocket thrust is typically measured using a load cell, the low thrust levels associated with electric propulsion (EP) systems necessitate the use of much more sensitive measurement techniques. The design and development of electric propulsion thrust stands that employ a conventional hanging pendulum arm connected to a balance mechanism consisting of a secondary arm and variable linkage have been reported in recent publications by Polzin et al. These works focused on performing steady-state thrust measurements and employed a static analysis of the thrust stand response. In the present work, we present a calibration method and data that will permit pulsed thrust measurements using the Variable Amplitude Hanging Pendulum with Extended Range (VAHPER) thrust stand. Pulsed thrust measurements are challenging in general because the pulsed thrust (impulse bit) occurs over a short timescale (typically 1 micros to 1 millisecond) and cannot be resolved directly. Consequently, the imparted impulse bit must be inferred through observation of the change in thrust stand motion effected by the pulse. Pulsed thrust measurements have typically only consisted of single-shot operation. In the present work, we discuss repetition-rate pulsed thruster operation and describe a method to perform these measurements. The thrust stand response can be modeled as a spring-mass-damper system with a repetitive delta forcing function to represent the impulsive action of the thruster.

  16. Generic Sensor Modeling Using Pulse Method

    NASA Technical Reports Server (NTRS)

    Helder, Dennis L.; Choi, Taeyoung

    2005-01-01

    Recent development of high spatial resolution satellites such as IKONOS, Quickbird and Orbview enable observation of the Earth's surface with sub-meter resolution. Compared to the 30 meter resolution of Landsat 5 TM, the amount of information in the output image was dramatically increased. In this era of high spatial resolution, the estimation of spatial quality of images is gaining attention. Historically, the Modulation Transfer Function (MTF) concept has been used to estimate an imaging system's spatial quality. Sometimes classified by target shapes, various methods were developed in laboratory environment utilizing sinusoidal inputs, periodic bar patterns and narrow slits. On-orbit sensor MTF estimation was performed on 30-meter GSD Landsat4 Thematic Mapper (TM) data from the bridge pulse target as a pulse input . Because of a high resolution sensor s small Ground Sampling Distance (GSD), reasonably sized man-made edge, pulse, and impulse targets can be deployed on a uniform grassy area with accurate control of ground targets using tarps and convex mirrors. All the previous work cited calculated MTF without testing the MTF estimator's performance. In previous report, a numerical generic sensor model had been developed to simulate and improve the performance of on-orbit MTF estimating techniques. Results from the previous sensor modeling report that have been incorporated into standard MTF estimation work include Fermi edge detection and the newly developed 4th order modified Savitzky-Golay (MSG) interpolation technique. Noise sensitivity had been studied by performing simulations on known noise sources and a sensor model. Extensive investigation was done to characterize multi-resolution ground noise. Finally, angle simulation was tested by using synthetic pulse targets with angles from 2 to 15 degrees, several brightness levels, and different noise levels from both ground targets and imaging system. As a continuing research activity using the developed sensor

  17. Pulse-to-pulse polarization-switching method for high-repetition-rate lasers

    NASA Astrophysics Data System (ADS)

    Hahne, Steffen; Johnston, Benjamin F.; Withford, Michael J.

    2007-02-01

    We report a method that enables dynamic switching of the pulse-to-pulse linear polarization orientation of a high-pulse-rate laser. The implications for laser micromachining, where polarization direction can be important, are also discussed.

  18. Chaotic carrier pulse position modulation communication system and method

    DOEpatents

    Abarbanel, Henry D. I.; Larson, Lawrence E.; Rulkov, Nikolai F.; Sushchik, Mikhail M.; Tsimring, Lev S.; Volkovskii, Alexander R.

    2001-01-01

    A chaotic carrier pulse position modulation communication system and method is disclosed. The system includes a transmitter and receiver having matched chaotic pulse regenerators. The chaotic pulse regenerator in the receiver produces a synchronized replica of a chaotic pulse train generated by the regenerator in the transmitter. The pulse train from the transmitter can therefore act as a carrier signal. Data is encoded by the transmitter through selectively altering the interpulse timing between pulses in the chaotic pulse train. The altered pulse train is transmitted as a pulse signal. The receiver can detect whether a particular interpulse interval in the pulse signal has been altered by reference to the synchronized replica it generates, and can therefore detect the data transmitted by the receiver. Preferably, the receiver predicts the earliest moment in time it can expect a next pulse after observation of at least two consecutive pulses. It then decodes the pulse signal beginning at a short time before expected arrival of a pulse.

  19. Radiolysis and pulse radiolysis of chlorinated phenols in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Getoff, N.; Solar, S.

    The radiation induced decomposition of 2-, 3- and 4-chlorophenols was studied under steady-state conditions. The rate constants for the reactions of H, OH and e -ag with 2-Cl-phenol were determined. Absorptions spectra of the H- and OH- adducts are presented.

  20. Method and apparatus for pulse stacking

    DOEpatents

    Harney, Robert C.

    1977-01-01

    An active pulse stacking system including an etalon and an electro-optical modulator apparatus combined with a pulse-forming network capable of forming and summing a sequence of time-delayed optical waveforms arising from, for example, a single laser pulse. The Pockels cell pulse stacker may attain an efficiency of about 2.6% while providing a controllable faster-than-exponential time rise in transmitted pulse intensity.

  1. Reaction mechanisms in the radiolysis of peptides, polypeptides and proteins

    SciTech Connect

    Garrison, W.M.

    1985-01-01

    The purpose of this review is to bring together and to correlate the wide variety of experimental studies that provide information on the reaction products and reaction mechanisms involved in the radiolysis of peptides, polypeptides and proteins (including chromosomal proteins) in both aqueous and solid-state systems. The comparative radiation chemistry of these systems is developed in terms of specific reactions of the peptide main-chain and the aliphatic, aromatic-unsaturated and sulfur-containing side-chains. Information obtained with the various experimental techniques of product analysis, competition kinetics, spin-trapping, pulse radiolysis and ESR spectroscopy is included. 147 refs.

  2. Radiolysis of berberine or palmatine in aqueous solution

    NASA Astrophysics Data System (ADS)

    Marszalek, Milena; Wolszczak, Marian

    2011-01-01

    The reactions of hydrated electron (eaq-), hydrogen atom (H rad ) (reducing species) and Cl2•-, Br2•-, N,O•H radicals (oxidizing species) with berberine or palmatine in aqueous solution have been studied by steady-state and pulse radiolysis. The spectra of transient intermediates, leading to the final products, are presented. The rate constants of the reaction of eaq- and rad OH radical with both alkaloids in the homogenous solution and in the presence of DNA are reported. It is demonstrated that the primary products of the reaction of berberine and palmatine with eaq- and radicals generated during radiolysis are unstable and undergo further reactions.

  3. Radiolysis Process Model

    SciTech Connect

    Buck, Edgar C.; Wittman, Richard S.; Skomurski, Frances N.; Cantrell, Kirk J.; McNamara, Bruce K.; Soderquist, Chuck Z.

    2012-07-17

    Assessing the performance of spent (used) nuclear fuel in geological repository requires quantification of time-dependent phenomena that may influence its behavior on a time-scale up to millions of years. A high-level waste repository environment will be a dynamic redox system because of the time-dependent generation of radiolytic oxidants and reductants and the corrosion of Fe-bearing canister materials. One major difference between used fuel and natural analogues, including unirradiated UO2, is the intense radiolytic field. The radiation emitted by used fuel can produce radiolysis products in the presence of water vapor or a thin-film of water (including OH• and H• radicals, O2-, eaq, H2O2, H2, and O2) that may increase the waste form degradation rate and change radionuclide behavior. H2O2 is the dominant oxidant for spent nuclear fuel in an O2 depleted water environment, the most sensitive parameters have been identified with respect to predictions of a radiolysis model under typical conditions. As compared with the full model with about 100 reactions it was found that only 30-40 of the reactions are required to determine [H2O2] to one part in 10–5 and to preserve most of the predictions for major species. This allows a systematic approach for model simplification and offers guidance in designing experiments for validation.

  4. Vesicles sensing using resistive-pulse method

    NASA Astrophysics Data System (ADS)

    Rudzevich, Yauheni; Lin, Yuqing; Chow, Lee

    2013-03-01

    Here we present a ``resistive-pulse'' method that allows translocations, counting and measuring size distribution liposomes with radii from 25 nm to 125 nm. This technique is based on using two chambers filled with electrolyte solution and separated by a partition with a nanopore between electrodes. It was found that ionic current drops when nanoparticle entering sensing nanopore of a pulled glass micropipette, producing a clear translocation signal. Pulled borosilicate micropipette with opening 50 ~ 150 nm was used as a sensing instrument. This method provides a direct, fast and inexpensive way to characterize inorganic and organic nanoparticles in a solution. LC acknowledges the financial support of National Science Foundation through Grant ECCS 0901361.

  5. Excited states and reduced and oxidized forms of a textile diazo dye, naphthol blue black. Spectral characterization using laser flash photolysis and pulse radiolysis studies

    NASA Astrophysics Data System (ADS)

    Nasr, Chouhaid; Vinodgopal, K.; Hotchandani, Surat; Chattopadhyay, A. K.; Kamat, Prashant V.

    1997-01-01

    The excited singlet and triplet states of a diazo textile dye (Naphthol Blue Black) have been investigated by pico and nanosecond flash photolysis. The excited singlet state shows a difference absorption maximum at 500 nm and has a lifetime of 25-30 ps in ethanol. The triplet excited state generated by triplet-triplet energy transfer shows an absorption maxima at 710-730 nm. The oxidized form as well as the reduced form of the diazo dye have been generated pulse radiolytically by reacting with azide and e aq radicals, respectively. Preliminary results of the photoelectrochemical irreversible reduction of Naphthol Blue Black in colloidal TiO 2 are also reported.

  6. Reduction of reversed micelle entrapped cytochrome c and cytochrome c/sub 3/ by electrons generated by pulse radiolysis or by pyrene photoionization

    SciTech Connect

    Vlsser, A.J.W.G.; Fendler, J.H.

    1982-03-18

    Horse heart cytochrome c and cytochrome c/sub 3/, isolated from Desulfovibrio vulgaris, have been incorporated in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) entrapped water pools in heptane. The absorption spectra of the cytochromes have been found to be strongly dependent on the water to AOT concentration ratios. The proteins solubilized in heptane by the AOT reversed micelles have retained their ability to mediate electron transfer. They reacted very rapidly with hydrated electrons, generated pulse radiolytically or, alternatively, formed in the laser photoionization of pyrene.

  7. Pulsed neutron well logging system and method with synchronization/stabilization pulse verification means

    SciTech Connect

    Brown, W.K.

    1982-07-13

    A well logging system and method involves the use of a well logging tool in a borehole traversing an earth formation which includes a pulsed neutron generator periodically bombarding the earth formation with neutrons. A scintillation-type detector detects gamma radiation from the earth formation and provides electrical data pulses corresponding in pulse height and frequency to the detected gamma radiation. Another circuit provides synchronization/stabilization pulses which are time related to the neutron bombardments of the formation. A cable conducts the data pulses and the synchronization/stabilization pulses uphole to surface electronics. A receiver with surface electronics processes the pulses and provides them to a gate circuit which passes or blocks the data pulses and the synchronization/stabilization pulses in accordance with a gate signal. The passed pulses are provided to a pulse height analyzer. The synchronization/stabilization pulses are also provided by the receiver to a gate signal network which provides the gate signal in accordance with the synchronization/stabilization pulses.

  8. Pulsed source ion implantation apparatus and method

    DOEpatents

    Leung, K.N.

    1996-09-24

    A new pulsed plasma-immersion ion-implantation apparatus that implants ions in large irregularly shaped objects to controllable depth without overheating the target, minimizing voltage breakdown, and using a constant electrical bias applied to the target. Instead of pulsing the voltage applied to the target, the plasma source, for example a tungsten filament or a RF antenna, is pulsed. Both electrically conducting and insulating targets can be implanted. 16 figs.

  9. Pulsed source ion implantation apparatus and method

    DOEpatents

    Leung, Ka-Ngo

    1996-01-01

    A new pulsed plasma-immersion ion-implantation apparatus that implants ions in large irregularly shaped objects to controllable depth without overheating the target, minimizing voltage breakdown, and using a constant electrical bias applied to the target. Instead of pulsing the voltage applied to the target, the plasma source, for example a tungsten filament or a RF antenna, is pulsed. Both electrically conducting and insulating targets can be implanted.

  10. Stably operating pulse combustor and method

    DOEpatents

    Zinn, Ben T.; Reiner, David

    1990-01-01

    A pulse combustor apparatus adapted to burn either a liquid fuel or a pulverized solid fuel within a preselected volume of the combustion chamber. The combustion process is substantially restricted to an optimum combustion zone in order to attain effective pulse combustion operation.

  11. Stably operating pulse combustor and method

    DOEpatents

    Zinn, B.T.; Reiner, D.

    1990-05-29

    A pulse combustor apparatus is described which is adapted to burn either a liquid fuel or a pulverized solid fuel within a preselected volume of the combustion chamber. The combustion process is substantially restricted to an optimum combustion zone in order to attain effective pulse combustion operation. 4 figs.

  12. Pulse front adaptive optics: a new method for control of ultrashort laser pulses.

    PubMed

    Sun, Bangshan; Salter, Patrick S; Booth, Martin J

    2015-07-27

    Ultrafast lasers enable a wide range of physics research and the manipulation of short pulses is a critical part of the ultrafast tool kit. Current methods of laser pulse shaping are usually considered separately in either the spatial or the temporal domain, but laser pulses are complex entities existing in four dimensions, so full freedom of manipulation requires advanced forms of spatiotemporal control. We demonstrate through a combination of adaptable diffractive and reflective optical elements - a liquid crystal spatial light modulator (SLM) and a deformable mirror (DM) - decoupled spatial control over the pulse front (temporal group delay) and phase front of an ultra-short pulse was enabled. Pulse front modulation was confirmed through autocorrelation measurements. This new adaptive optics technique, for the first time enabling in principle arbitrary shaping of the pulse front, promises to offer a further level of control for ultrafast lasers. PMID:26367595

  13. Apparatus and method for optical pulse measurement

    SciTech Connect

    Trebino, R.P.; Tsang, T.; Fittinghoff, D.N.; Sweetser, J.N.; Krumbuegel, M.A.

    1999-12-28

    Practical third-order frequency-resolved optical grating (FROG) techniques for characterization of ultrashort optical pulses are disclosed. The techniques are particularly suited to the measurement of single and/or weak optical pulses having pulse durations in the picosecond and subpicosecond regime. The relative quantum inefficiency of third-order nonlinear optical effects is compensated for through (i) use of phase-matched transient grating beam geometry to maximize interaction length, and (ii) use of interface-enhanced third-harmonic generation.

  14. Apparatus and method for optical pulse measurement

    DOEpatents

    Trebino, Rick P.; Tsang, Thomas; Fittinghoff, David N.; Sweetser, John N.; Krumbuegel, Marco A.

    1999-12-28

    Practical third-order frequency-resolved optical grating (FROG) techniques for characterization of ultrashort optical pulses are disclosed. The techniques are particularly suited to the measurement of single and/or weak optical pulses having pulse durations in the picosecond and subpicosecond regime. The relative quantum inefficiency of third-order nonlinear optical effects is compensated for through i) use of phase-matched transient grating beam geometry to maximize interaction length, and ii) use of interface-enhanced third-harmonic generation.

  15. Multiple laser pulse ignition method and apparatus

    DOEpatents

    Early, J.W.

    1998-05-26

    Two or more laser light pulses with certain differing temporal lengths and peak pulse powers can be employed sequentially to regulate the rate and duration of laser energy delivery to fuel mixtures, thereby improving fuel ignition performance over a wide range of fuel parameters such as fuel/oxidizer ratios, fuel droplet size, number density and velocity within a fuel aerosol, and initial fuel temperatures. 18 figs.

  16. Multiple laser pulse ignition method and apparatus

    DOEpatents

    Early, James W.

    1998-01-01

    Two or more laser light pulses with certain differing temporal lengths and peak pulse powers can be employed sequentially to regulate the rate and duration of laser energy delivery to fuel mixtures, thereby improving fuel ignition performance over a wide range of fuel parameters such as fuel/oxidizer ratios, fuel droplet size, number density and velocity within a fuel aerosol, and initial fuel temperatures.

  17. Simulation of FEL pulse length calculation with THz streaking method.

    PubMed

    Gorgisyan, I; Ischebeck, R; Prat, E; Reiche, S; Rivkin, L; Juranić, P

    2016-05-01

    Having accurate and comprehensive photon diagnostics for the X-ray pulses delivered by free-electron laser (FEL) facilities is of utmost importance. Along with various parameters of the photon beam (such as photon energy, beam intensity, etc.), the pulse length measurements are particularly useful both for the machine operators to measure the beam parameters and monitor the stability of the machine performance, and for the users carrying out pump-probe experiments at such facilities to better understand their measurement results. One of the most promising pulse length measurement techniques used for photon diagnostics is the THz streak camera which is capable of simultaneously measuring the lengths of the photon pulses and their arrival times with respect to the pump laser. This work presents simulations of a THz streak camera performance. The simulation procedure utilizes FEL pulses with two different photon energies in hard and soft X-ray regions, respectively. It recreates the energy spectra of the photoelectrons produced by the photon pulses and streaks them by a single-cycle THz pulse. Following the pulse-retrieval procedure of the THz streak camera, the lengths were calculated from the streaked spectra. To validate the pulse length calculation procedure, the precision and the accuracy of the method were estimated for streaking configuration corresponding to previously performed experiments. The obtained results show that for the discussed setup the method is capable of measuring FEL pulses with about a femtosecond accuracy and precision. PMID:27140142

  18. Simulation of FEL pulse length calculation with THz streaking method

    PubMed Central

    Gorgisyan, I.; Ischebeck, R.; Prat, E.; Reiche, S.; Rivkin, L.; Juranić, P.

    2016-01-01

    Having accurate and comprehensive photon diagnostics for the X-ray pulses delivered by free-electron laser (FEL) facilities is of utmost importance. Along with various parameters of the photon beam (such as photon energy, beam intensity, etc.), the pulse length measurements are particularly useful both for the machine operators to measure the beam parameters and monitor the stability of the machine performance, and for the users carrying out pump–probe experiments at such facilities to better understand their measurement results. One of the most promising pulse length measurement techniques used for photon diagnostics is the THz streak camera which is capable of simultaneously measuring the lengths of the photon pulses and their arrival times with respect to the pump laser. This work presents simulations of a THz streak camera performance. The simulation procedure utilizes FEL pulses with two different photon energies in hard and soft X-ray regions, respectively. It recreates the energy spectra of the photoelectrons produced by the photon pulses and streaks them by a single-cycle THz pulse. Following the pulse-retrieval procedure of the THz streak camera, the lengths were calculated from the streaked spectra. To validate the pulse length calculation procedure, the precision and the accuracy of the method were estimated for streaking configuration corresponding to previously performed experiments. The obtained results show that for the discussed setup the method is capable of measuring FEL pulses with about a femtosecond accuracy and precision. PMID:27140142

  19. PULSE RADIOLYSIS IN SUPERCRITICAL RARE GAS FLUIDS

    SciTech Connect

    HOLROYD,R.

    2007-01-01

    Recently, supercritical fluids have become quite popular in chemical and semiconductor industries for applications in chemical synthesis, extraction, separation processes, and surface cleaning. These applications are based on: the high dissolving power due to density build-up around solute molecules, and the ability to tune the conditions of a supercritical fluid, such as density and temperature, that are most suitable for a particular reaction. The rare gases also possess these properties and have the added advantage of being supercritical at room temperature. Information about the density buildup around both charged and neutral species can be obtained from fundamental studies of volume changes in the reactions of charged species in supercritical fluids. Volume changes are much larger in supercritical fluids than in ordinary solvents because of their higher compressibility. Hopefully basic studies, such as discussed here, of the behavior of charged species in supercritical gases will provide information useful for the utilization of these solvents in industrial applications.

  20. Studies of ion solvation using pulse radiolysis

    SciTech Connect

    Jonah, C.D.; Lin, Yi.

    1991-01-01

    In this paper we describe our measurements of ion solvation in a series of alcohols. Benzophenone is dissolved in an alcohol at a sufficiently high concentration so that the electrons formed by radiation will react with the benzophenone molecule to form the anion. The spectrum of the anion is then observed as a function of time. As the benzophenone anion solvates, the spectrum shifts to the blue. The results of our measurements clearly show that both the size of the solvent molecules and their shapes are important in the solvation process. Different spectral relaxation processes are observed for ions than are observed for electron solvation, the simple'' ion system that has been most heavily studied. In addition, these results suggest that the rate of solvation may be different for ions in solution than for dipoles in solution. 26 refs., 3 figs.

  1. Laser pulse stretcher method and apparatus

    DOEpatents

    Hawkins, Jon K.; Williams, William A.

    1990-01-01

    The output of an oscillator stage of a laser system is monitored by a photocell which is coupled to a feedback section to control a Pockels Cell and change the light output of the oscillator stage. A synchronizing pulse is generated in timed relation to the initiation of operation of the oscillator stage and is applied to a forward feed section which cooperates with the feedback section to maintain the light output constant for an extended time interval.

  2. Laser pulse detection method and apparatus

    NASA Technical Reports Server (NTRS)

    Goss, Willis C. (Inventor); Janesick, James R. (Inventor)

    1987-01-01

    A sensor is described for detecting the difference in phase of a pair of returned light pulse components, such as the two components of a light pulse of an optical gyro. In an optic gyro, the two light components have passed in opposite directions through a coil of optical fiber, with the difference in phase of the returned light components determining the intensity of light shining on the sensor. The sensor includes a CCD (charge coupled device) that receives the pair of returned light components to generate a charge proportional to the number of photons in the received light. The amount of the charge represents the phase difference between the two light components. At a time after the transmission of the light pulse and before the expected time of arrival of the interfering light components, charge accumulating in the CCD as a result of reflections from optical components in the system, are repeatedly removed from the CCD, by transferring out charges in the CCD and dumping these charges.

  3. Pulsed interrupter and method of operation

    SciTech Connect

    Drake, Joel Lawton; Kratz, Robert

    2015-06-09

    Some embodiments provide interrupter systems comprising: a first electrode; a second electrode; a piston movably located at a first position and electrically coupled with the first and second electrodes establishing a closed state, the piston comprises an electrical conductor that couples with the first and second electrodes providing a conductive path; an electromagnetic launcher configured to, when activated, induce a magnetic field pulse causing the piston to move away from the electrical coupling with the first and second electrodes establishing an open circuit between the first and second electrodes; and a piston control system comprising a piston arresting system configured to control a deceleration of the piston following the movement of the piston induced by the electromagnetic launcher such that the piston is not in electrical contact with at least one of the first electrode and the second electrode when in the open state.

  4. Method and apparatus for analog pulse pile-up rejection

    DOEpatents

    De Geronimo, Gianluigi

    2013-12-31

    A method and apparatus for pulse pile-up rejection are disclosed. The apparatus comprises a delay value application constituent configured to receive a threshold-crossing time value, and provide an adjustable value according to a delay value and the threshold-crossing time value; and a comparison constituent configured to receive a peak-occurrence time value and the adjustable value, compare the peak-occurrence time value with the adjustable value, indicate pulse acceptance if the peak-occurrence time value is less than or equal to the adjustable value, and indicate pulse rejection if the peak-occurrence time value is greater than the adjustable value.

  5. Method and apparatus for analog pulse pile-up rejection

    DOEpatents

    De Geronimo, Gianluigi

    2014-11-18

    A method and apparatus for pulse pile-up rejection are disclosed. The apparatus comprises a delay value application constituent configured to receive a threshold-crossing time value, and provide an adjustable value according to a delay value and the threshold-crossing time value; and a comparison constituent configured to receive a peak-occurrence time value and the adjustable value, compare the peak-occurrence time value with the adjustable value, indicate pulse acceptance if the peak-occurrence time value is less than or equal to the adjustable value, and indicate pulse rejection if the peak-occurrence time value is greater than the adjustable value.

  6. Frequency-Domain Methods for Characterization of Pulsed Power Diagnostics

    SciTech Connect

    White, A D; Anderson, R A; Ferriera, T J; Goerz, D A

    2009-07-27

    This paper discusses methods of frequency-domain characterization of pulsed power sensors using vector network analyzer and spectrum analyzer techniques that offer significant simplification over time-domain methods, while mitigating or minimizing the effect of the difficulties present in time domain characterization. These methods are applicable to characterization of a wide variety of sensors.

  7. Neural network and area method interpretation of pulsed experiments

    SciTech Connect

    Dulla, S.; Picca, P.; Ravetto, P.; Canepa, S.

    2012-07-01

    The determination of the subcriticality level is an important issue in accelerator-driven system technology. The area method, originally introduced by N. G. Sjoestrand, is a classical technique to interpret flux measurement for pulsed experiments in order to reconstruct the reactivity value. In recent times other methods have also been developed, to account for spatial and spectral effects, which were not included in the area method, since it is based on the point kinetic model. The artificial neural network approach can be an efficient technique to infer reactivities from pulsed experiments. In the present work, some comparisons between the two methods are carried out and discussed. (authors)

  8. Radiolysis of Bicarbonate and Carbonate Aqueous Solutions: Product Analysis and Simulation of Radiolytic Processes

    SciTech Connect

    Cai Zhongli; Li Xifeng; Katsumura, Yosuke; Urabe, Osamu

    2001-11-15

    An understanding of the radiation-induced effects in groundwater is essential to evaluate the safe geological disposal of spent fuel. In groundwater, the bicarbonate ion is the predominant and common anion; this work investigated radiation-induced chemical reactions of (bi)carbonate aqueous solutions with steady-state irradiation and pulse radiolysis methods. Aqueous solutions of sodium (bi)carbonate as high as 50 mmol.dm{sup -3} were used. The formation of formate, oxalate, and H{sub 2}O{sub 2} were measured under different conditions. A complete set of reaction steps and reliable kinetic data for the radiolysis of (bi)carbonate aqueous solutions at ionic strength close to the groundwater were proposed. Kinetic calculations were completed based on the proposed reaction steps and the kinetic data obtained in the present work. The results from the calculation are in good agreement with the experimental results. With these proposed reaction steps and kinetic data, computer simulation can be performed to predict the yield of radiolytic products of (bi)carbonate aqueous solutions as a function of irradiation time and used to evaluate the safety of geological disposal options of spent fuel.

  9. Methods and devices for generation of broadband pulsed radiation

    DOEpatents

    Borguet, Eric; Isaienko, Oleksandr

    2013-05-14

    Methods and apparatus for non-collinear optical parametric ampliffication (NOPA) are provided. Broadband phase matching is achieved with a non-collinear geometry and a divergent signal seed to provide bandwidth gain. A chirp may be introduced into the pump pulse such that the white light seed is amplified in a broad spectral region.

  10. Method and apparatus for characterizing reflected ultrasonic pulses

    NASA Technical Reports Server (NTRS)

    Yost, William T. (Inventor); Cantrell, John H., Jr. (Inventor)

    1991-01-01

    The invention is a method of and apparatus for characterizing the amplitudes of a sequence of reflected pulses R1, R2, and R3 by converting them into corresponding electric signals E1, E2, and E3 to substantially the same value during each sequence thereby restoring the reflected pulses R1, R2, and R3 to their initial reflection values by timing means, an exponential generator, and a time gain compensator. Envelope and baseline reject circuits permit the display and accurate location of the time spaced sequence of electric signals having substantially the same amplitude on a measurement scale on a suitable video display or oscilloscope.

  11. Radiolysis of crystalline nickel oxalates

    NASA Astrophysics Data System (ADS)

    Basahel, S. N.; Diefallah, El-H. M.; El-Fass, M. M.; Al-Sabban, E. A.

    Radiolysis of crystalline K 2Ni(C 2O 4) 2);6H 2O, K 2Ni(C 2O 4) 2 and Ni(C 2O 4));2H 2O has been investigated. The results showed that in K 2Ni(C 2O 4) 2);6H 2O, the initial G(Ni 3+) has a value of 3.75 and drops to about 1.27 when the dose approaches 1.2 × 10 22 eV g -1. The decrease in G(Ni 3+) with increasing radiation dose is accompanied with an increase in G(Ni 2+). In the irradiated anhydrated complex, the results however show an increase in G(Ni 3+) and a decrease in G(Ni 2+) with increasing radiation dose. The radiolysis of Ni(C 2O 4)·2H 2O showed an increase in G(Ni 3+) with increasing radiation dose. A mechanism has been suggested to explain the observed results.

  12. In honour of N. Yngve Öhrn: surveying proton cancer therapy reactions with Öhrn's electron nuclear dynamics method. Aqueous clusters radiolysis and DNA-base damage by proton collisions

    NASA Astrophysics Data System (ADS)

    Mclaurin, Patrick M.; Privett, Austin J.; Stopera, Christopher; Grimes, Thomas V.; Perera, Ajith; Morales, Jorge A.

    2015-02-01

    Proton cancer therapy (PCT) utilises high-energy H+ projectiles to cure cancer. PCT healing arises from its DNA damage in cancerous cells, which is mostly inflicted by the products from PCT water radiolysis reactions. While clinically established, a complete microscopic understanding of PCT remains elusive. To help in the microscopic elucidation of PCT, Professor Öhrn's simplest-level electron nuclear dynamics (SLEND) method is herein applied to H+ + (H2O)3-4 and H+ + DNA-bases at ELab = 1.0 keV. These are two types of computationally feasible prototypes to study water radiolysis reactions and H+-induced DNA damage, respectively. SLEND is a time-dependent, variational, non-adiabatic and direct-dynamics method that adopts a nuclear classical-mechanics description and an electronic single-determinantal wavefunction. Additionally, our SLEND + effective-core-potential method is herein employed to simulate some computationally demanding PCT reactions. Due to these attributes, SLEND proves appropriate for the simulation of various types of PCT reactions accurately and feasibly. H+ + (H2O)3-4 simulations reveal two main processes: H+ projectile scattering and the simultaneous formation of H and OH fragments; the latter process is quantified through total integrals cross sections. H+ + DNA-base simulations reveal atoms and groups displacements, ring openings and base-to-proton electron transfers as predominant damage processes. The authors warmly dedicate this SLEND investigation in honour of Professor N. Yngve Öhrn on the occasion of his 80th birthday celebration during the 54th Sanibel Symposium in St. Simons' Island, Georgia, on February 16-21, 2014. Associate Professor Jorge A. Morales was a former chemistry PhD student under the mentorship of Professor Öhrn and Dr Ajith Perera took various quantum chemistry courses taught by Professor Öhrn during his chemistry PhD studies. Both Jorge and Ajith look back to those great times of their scientific formation under

  13. Studies on oxidative radiolysis of ibuprofen in presence of potassium persulfate

    NASA Astrophysics Data System (ADS)

    Paul (Guin), Jhimli; Naik, D. B.; Bhardwaj, Y. K.; Varshney, Lalit

    2014-07-01

    The radiolysis of ibuprofen (IBP), a model pharmaceutical compound, was studied by gamma irradiation in an aqueous solution in the presence and absence of potassium persulfate (K2S2O8). The extent of mineralization was investigated by measuring the UV-visible spectra, decrease in the chemical oxygen demand (COD) and the total organic carbon (TOC) content of aqueous IBP solution at different doses. The gamma radiolysis, in the presence of K2S2O8, required much lesser dose compared to in the absence of K2S2O8 for the same extent of mineralization of aqueous IBP solution. The pulse radiolysis of IBP was carried out under different radiolytic conditions to understand the mechanism of efficient mineralization of IBP during gamma radiolysis in the presence of K2S2O8. It was found that unlike OH radical, SO4- radical preferentially produces benzyl type of radicals via the formation of the benzene radical cation. The results concluded that the gamma radiolysis in presence of K2S2O8 could be one of the efficient advanced oxidation processes for degradation of pharmaceutical compounds present in the aqueous solution.

  14. Long-laser-pulse method of producing thin films

    DOEpatents

    Balooch, Mehdi; Olander, Donald K.; Russo, Richard E.

    1991-01-01

    A method of depositing thin films by means of laser vaporization employs a long-pulse laser (Nd-glass of about one millisecond duration) with a peak power density typically in the range 10.sup.5 -10.sup.6 W/cm.sup.2. The method may be used to produce high T.sub.c superconducting films of perovskite material. In one embodiment, a few hundred nanometers thick film of YBa.sub.2 Cu.sub.3 O.sub.7-x is produced on a SrTiO.sub.3 crystal substrate in one or two pulses. In situ-recrystallization and post-annealing, both at elevated temperature and in the presence of an oxidizing agen The invention described herein arose in the course of, or under, Contract No. DE-C03-76SF0098 between the United States Department of Energy and the University of California.

  15. Pulse

    MedlinePlus

    Heart rate; Heart beat ... The pulse can be measured at areas where an artery passes close to the skin. These areas include the: ... side of the foot Wrist To measure the pulse at the wrist, place the index and middle ...

  16. Method and means of transmitting and receiving broad-band unipolar, ultrasonic pulses for ultrasonic inspection

    DOEpatents

    Thompson, D.O.; Hsu, D.K.

    1993-12-14

    The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses. 25 figures.

  17. Method and means of transmitting and receiving broad-band unipolar, ultrasonic pulses for ultrasonic inspection

    DOEpatents

    Thompson, Donald O.; Hsu, David K.

    1993-12-14

    The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses.

  18. A new pulsed laser deposition technique: scanning multi-component pulsed laser deposition method.

    PubMed

    Fischer, D; de la Fuente, G F; Jansen, M

    2012-04-01

    The scanning multi-component pulsed laser deposition (PLD) method realizes uniform depositions of desired coatings by a modified pulsed laser deposition process, preferably with a femto-second laser-system. Multi-component coatings (single or multilayered) are thus deposited onto substrates via laser induced ablation of segmented targets. This is achieved via horizontal line-scanning of a focused laser beam over a uniformly moving target's surface. This process allows to deposit the desired composition of the coating simultaneously, starting from the different segments of the target and adjusting the scan line as a function of target geometry. The sequence and thickness of multilayers can easily be adjusted by target architecture and motion, enabling inter/intra layer concentration gradients and thus functional gradient coatings. This new, simple PLD method enables the achievement of uniform, large-area coatings. Case studies were performed with segmented targets containing aluminum, titanium, and niobium. Under the laser irradiation conditions applied, all three metals were uniformly ablated. The elemental composition within the rough coatings obtained was fixed by the scanned area to Ti-Al-Nb = 1:1:1. Crystalline aluminum, titanium, and niobium were found to coexist side by side at room temperature within the substrate, without alloy formation up to 600 °C. PMID:22559543

  19. A new pulsed laser deposition technique: Scanning multi-component pulsed laser deposition method

    SciTech Connect

    Fischer, D.; Jansen, M.; Fuente, G. F. de la

    2012-04-15

    The scanning multi-component pulsed laser deposition (PLD) method realizes uniform depositions of desired coatings by a modified pulsed laser deposition process, preferably with a femto-second laser-system. Multi-component coatings (single or multilayered) are thus deposited onto substrates via laser induced ablation of segmented targets. This is achieved via horizontal line-scanning of a focused laser beam over a uniformly moving target's surface. This process allows to deposit the desired composition of the coating simultaneously, starting from the different segments of the target and adjusting the scan line as a function of target geometry. The sequence and thickness of multilayers can easily be adjusted by target architecture and motion, enabling inter/intra layer concentration gradients and thus functional gradient coatings. This new, simple PLD method enables the achievement of uniform, large-area coatings. Case studies were performed with segmented targets containing aluminum, titanium, and niobium. Under the laser irradiation conditions applied, all three metals were uniformly ablated. The elemental composition within the rough coatings obtained was fixed by the scanned area to Ti-Al-Nb = 1:1:1. Crystalline aluminum, titanium, and niobium were found to coexist side by side at room temperature within the substrate, without alloy formation up to 600 deg. C.

  20. Investigation of honeycomb structure using pulse infrared thermography method

    NASA Astrophysics Data System (ADS)

    Li, Huijuan

    2010-11-01

    To reduce weight and improve strength in the aerospace industry, composite structure has gained popularity as a replacement for conventional materials and structures, such as adhesive bonding and honeycomb structure. Honeycomb structures composed by a honeycomb core between two facesheets are very common on aerospace parts. However, the adhesive bonding process is more susceptible to quality variations during manufacturing than traditional joining methods. With the large increase in the use of composite materials and honeycomb structures, the need for high speed, large area inspection for fracture critical, sub-surface defects in aircraft, missiles and marine composites led to broad acceptance of infrared based NDT methods. Infrared thermography is one of several non-destructive testing techniques which can be used for defect detection in aircraft materials. Infrared thermography can be potentially useful, as it is quick, real time, non-contact and can examine over a relatively large area in one inspection procedure. In this paper, two kinds of defects which are of various size, shape and location below the test surface are planted in the honeycomb structure, they are all tested by pulsed thermography, analyze the thermal sequence and intensity graph got by this methods, it shows that pulsed thermography is an effective nondestructive technique for inspecting disbonding defect, can distinguish the location and the dimension of the defect exactly.

  1. A method for suppression of pressure pulses in fluid-filled piping: Theoretical analysis

    SciTech Connect

    Shin, Y.W.; Wiedermann, A.H.

    1988-06-01

    A simple, nondestructive method to suppress pressure pulses in a fluid-filled piping is theoretically analyzed, and the result provides the basis needed for design and evaluation of a pressure-pulse suppression device based on the proposed theory. The method is based on forming of fluid jets in the event of a pressure surge such that the pulse height as well as the energy of the pulse are reduced. The result for pressure pulses in the range of practical interest shows that a substantial reduction can be attained in the pulse height with accompanied reduction of pulse energy remaining in the system. The analysis also reveals that a certain amount of trade-off exists in the design of the suppression device; a certain level of pulse energy remaining in the system must be accepted in order to limit the pulse height below a certain level and vice versa. 7 refs., 5 figs.

  2. Gamma and alpha radiolysis of salt brines

    SciTech Connect

    Gray, W.J.; Simonson, S.A.

    1984-11-01

    Gamma radiolysis of Permian Basin brine leads to equilibrium gas pressure of about 100 atm. at 75/sup 0/C and about 40 atm. at 150/sup 0/C, providing the gas space is very small and/or the total dose is very high. Dose rate dependence is being investigated but is not yet established. Alpha radiolysis of Permian Bsin brine is still being pursued, but it is clear that equilibrium gas pressures will be much higher than with gamma radiolysis. Gas compositions in all cases have been about two parts H/sub 2/ to one part O/sub 2/. Efforts to simulate these results with computer models have been quite successful. 8 references, 6 figures, 1 table.

  3. Pulse

    MedlinePlus

    ... resting for at least 10 minutes. Take the exercise heart rate while you are exercising. ... pulse rate can help determine if the patient's heart is pumping. ... rate gives information about your fitness level and health.

  4. Method of estimating pulse response using an impedance spectrum

    SciTech Connect

    Morrison, John L; Morrison, William H; Christophersen, Jon P; Motloch, Chester G

    2014-10-21

    Electrochemical Impedance Spectrum data are used to predict pulse performance of an energy storage device. The impedance spectrum may be obtained in-situ. A simulation waveform includes a pulse wave with a period greater than or equal to the lowest frequency used in the impedance measurement. Fourier series coefficients of the pulse train can be obtained. The number of harmonic constituents in the Fourier series are selected so as to appropriately resolve the response, but the maximum frequency should be less than or equal to the highest frequency used in the impedance measurement. Using a current pulse as an example, the Fourier coefficients of the pulse are multiplied by the impedance spectrum at corresponding frequencies to obtain Fourier coefficients of the voltage response to the desired pulse. The Fourier coefficients of the response are then summed and reassembled to obtain the overall time domain estimate of the voltage using the Fourier series analysis.

  5. Protection in radiolysis of n-hexadecane—I. Radiolysis of pure liquid n-hexadecane

    NASA Astrophysics Data System (ADS)

    Soebianto, Yanti S.; Yamaguchi, Tetsuro; Katsumura, Yosuke; Ishigure, Kenkichi; Kubo, Junichi; Koizumi, Takeo

    Radiolysis of pure liquid n-hexadecane under vacuum has been studied to obtain greater understanding about the effect of radiation on open chain polymers such as polyethylene. Gas chromatography, gel permeation chromatography and mass spectrometry have been used to analyze the radiolysis products and their yields have been determined. The gas products mainly contain H 2, the condensed products contain saturated and unsaturated scission products, hexadecene and crosslink products. Mass analysis of the condensed products shows unsaturations in the crosslink products.

  6. Continuous flow PCB radiolysis with real time assessment by gas chromatography

    SciTech Connect

    Bruce J. Mincher; Aaron Ruhter; Rene' Rodriguez; Richard Brey

    2006-05-01

    Recently, the treatment of environmentally recalcitrant pollutants such as PCBs has been studied using a number of so-called, “advanced oxidation technologies (AOTs).” As a group, the AOTs are ultimate treatment technologies that seek to mineralize the hazardous compounds to be treated (Cooper et al., 2004). One of the most versatile of the AOTs is radiolysis, usually practiced using machine-generated sources of radiation (Cooper et al., 2004, Mincher and Cooper, 2003). The radiolytic decomposition of PCBs has been reviewed (Curry and Mincher, 1999). While earlier experiments have been performed in alkaline isopropanol (Singh et al., 1985, Mucka et al., 1997), recent literature has begun to examine the radiolysis of PCBs in more “real-world” solvents, such as transformer oil (Arbon and Mincher, 1996, Mincher et al., 2000, Chaychian et al., 1999). These experiments have generally been performed in batch fashion, with small volumes of PCB-contaminated solvents placed in front of a gamma-ray source or the bremmstrahlung or e-beam of an accelerator for predetermined periods of time, to give a desired absorbed dose. These samples were then retrieved to analyze the post-irradiation PCB concentration. We report here what we believe is the first example of the radiolysis of PCBs in a process, continuous flow stream, as opposed to typical batch irradiations. The PCB-containing transformer oil was recirculated through an irradiation cell located in the path of an e-beam. Multiple passes through the cell allowed for the delivery of any desired radiation dose. This system required the development of an on-line analytical system that could provide PCB concentration values in real time. In the current experiment, a pulsed plasma electron capture detector (PDECD) was used in conjunction with a new sample preparation scheme. The new sampling scheme bypasses the need for removal or powering down of the radiation source, which would be undesirable during process PCB

  7. Stability of methyl p-hydroxybenzoate (methylparaben) to gamma radiolysis

    NASA Astrophysics Data System (ADS)

    Angelini, Giancarlo; Bucci, Roberto; Colosimo, Marcello; Margonelli, Andrea

    1998-01-01

    The stability of methyl p-hydroxybenzoate during 60Co γ-radiolysis was studied in the solid state and in 10 μM water solution. The work was undertaken as a model to be extended to radiolytic sterilization of pharmaceutical preparations. Only in water moderate decomposition was observed at high doses (50 KGy, whilst at 5 kGy sterilization was verified. Methylparaben labelled with carbon-14 on the carboxyl group provided the decomposition yield by the reverse isotope dilution method; mass balances were drawn and mechanisms suggested.

  8. INTERFACIAL RADIOLYSIS EFFECTS IN TANK WASTE SPECIATION

    EPA Science Inventory

    The purpose of this program is to deliver pertinent, though sometimes basic, information which can be used to make rational decisions on safety issues and processing strategies associated with mixed waste clean-up. In particular, we will establish an understanding of radiolysis i...

  9. A Comparison of the ?-Radiolysis of TODGA and T(EH)DGA Using UHPLC-ESI-MS Analysis

    SciTech Connect

    Zarzana, Chris A.; Groenewold, Gary S.; Mincher, Bruce J.; Mezyk, Stephen P.; Modolo, Giuseppe; Wildens, Andreas; Schmidt, Holgar; Wishart, James F.; Cook, Andrew R.

    2015-03-01

    Solutions of TODGA and T(EH)DGA in n-dodecane were subjected to ?-irradiation in the presence and absence of an aqueous nitric acid phase and analyzed using UHPLC-ESI-MS to determine the rates of radiolytic decay of the two extractants, as well as to identify radiolysis products. The DGA concentrations decreased exponentially with increasing dose, and the measured degradation rate constants were uninfluenced by the presence or absence of an acidic aqueous phase, or by chemical variations in the alkyl side-chains. The DGA degradation was attributed to reactions of the dodecane radical cation, whose kinetics were measured for TODGA using picosecond electron pulse radiolysis to be k2 = (9.72 ± 1.10) × 109 M-1 s-1. The identified radiolysis products suggest that the bonds most vulnerable to radiolytic attack are those in the diglycolamide center of these molecules and not on the side-chains.

  10. Monitoring of concrete structures using the ultrasonic pulse velocity method

    NASA Astrophysics Data System (ADS)

    Karaiskos, G.; Deraemaeker, A.; Aggelis, D. G.; Van Hemelrijck, D.

    2015-11-01

    Concrete is the material most produced by humanity. Its popularity is mainly based on its low production cost and great structural design flexibility. Its operational and ambient loadings including environmental effects have a great impact in the performance and overall cost of concrete structures. Thus, the quality control, the structural assessment, the maintenance and the reliable prolongation of the operational service life of the existing concrete structures have become a major issue. In the recent years, non-destructive testing (NDT) is becoming increasingly essential for reliable and affordable quality control and integrity assessment not only during the construction of new concrete structures, but also for the existing ones. Choosing the right inspection technique is always followed by a compromise between its performance and cost. In the present paper, the ultrasonic pulse velocity (UPV) method, which is the most well known and widely accepted ultrasonic concrete NDT method, is thoroughly reviewed and compared with other well-established NDT approaches. Their principles, inherent limitations and reliability are reviewed. In addition, while the majority of the current UPV techniques are based on the use of piezoelectric transducers held on the surface of the concrete, special attention is paid to a very promising technique using low-cost and aggregate-size piezoelectric transducers embedded in the material. That technique has been evaluated based on a series of parameters, such as the ease of use, cost, reliability and performance.

  11. Removal of chloroform from biodegradable therapeutic microspheres by radiolysis.

    PubMed

    Zielhuis, S W; Nijsen, J F W; Dorland, L; Krijger, G C; van Het Schip, A D; Hennink, W E

    2006-06-01

    Radioactive holmium-166 loaded poly(l-lactic acid) microspheres are promising systems for the treatment of liver malignancies. These microspheres are loaded with holmium acetylacetonate (HoAcAc) and prepared by a solvent evaporation method using chloroform. After preparation the microspheres (Ho-PLLA-MS) are activated by neutron irradiation in a nuclear reactor. It was observed that relatively large amounts of residual chloroform (1000-6000 ppm) remained in the microspheres before neutron irradiation. Since it is known that chloroform is susceptible for high-energy radiation, we investigated whether neutron and gamma irradiation could result in the removal of residual chloroform in HoAcAc-loaded and placebo PLLA-MS by radiolysis. To investigate this, microspheres with relatively high and low amounts of residual chloroform were subjected to irradiation. The effect of irradiation on the residual chloroform levels as well as other microsphere characteristics (morphology, size, crystallinity, molecular weight of PLLA and degradation products) were evaluated. No chloroform in the microspheres could be detected after neutron irradiation. This was also seen for gamma irradiation at a dose of 200 kGy phosgene, which can be formed as the result of radiolysis of chloroform, was not detected with gas chromatography-mass spectrometry (GC-MS). A precipitation titration showed that radiolysis of chloroform resulted in the formation of chloride. Gel permeation chromatography and differential scanning calorimetry showed a decrease in molecular weight of PLLA and crystallinity, respectively. However, no differences were observed between irradiated microsphere samples with high and low initial amounts of chloroform. In conclusion, this study demonstrates that neutron and gamma irradiation results in the removal of residual chloroform in PLLA-microspheres. PMID:16549282

  12. Method and apparatus for stabilizing pulsed microwave amplifiers

    DOEpatents

    Hopkins, Donald B.

    1993-01-01

    Phase and amplitude variations at the output of a high power pulsed microwave amplifier arising from instabilities of the driving electron beam are suppressed with a feed-forward system that can stabilize pulses which are too brief for regulation by conventional feedback techniques. Such variations tend to be similar during successive pulses. The variations are detected during each pulse by comparing the amplifier output with the low power input signal to obtain phase and amplitude error signals. This enables storage of phase and amplitude correction signals which are used to make compensating changes in the low power input signal during the following amplifier output pulse which suppress the variations. In the preferred form of the invention, successive increments of the correction signals for each pulse are stored in separate channels of a multi-channel storage. Sequential readout of the increments during the next pulse provides variable control voltages to a voltage controlled phase shifter and voltage controlled amplitude modulator in the amplifier input signal path.

  13. Method and apparatus for stabilizing pulsed microwave amplifiers

    DOEpatents

    Hopkins, D.B.

    1993-01-26

    Phase and amplitude variations at the output of a high power pulsed microwave amplifier arising from instabilities of the driving electron beam are suppressed with a feed-forward system that can stabilize pulses which are too brief for regulation by conventional feedback techniques. Such variations tend to be similar during successive pulses. The variations are detected during each pulse by comparing the amplifier output with the low power input signal to obtain phase and amplitude error signals. This enables storage of phase and amplitude correction signals which are used to make compensating changes in the low power input signal during the following amplifier output pulse which suppress the variations. In the preferred form of the invention, successive increments of the correction signals for each pulse are stored in separate channels of a multi-channel storage. Sequential readout of the increments during the next pulse provides variable control voltages to a voltage controlled phase shifter and voltage controlled amplitude modulator in the amplifier input signal path.

  14. MCFC performance diagnosis by using the current-pulse method

    NASA Astrophysics Data System (ADS)

    Sugiura, Kimihiko; Matsuoka, Hironori; Tanimoto, Kazumi

    Several problems prevent molten carbonate fuel cells (MCFC) operation for an extended period. However, if the degradation factors can be identified and resolved in a timely manner, MCFC could become a valuable technology. Therefore, a performance diagnosis should be developed which enables the simple and instantaneous determination of MCFC degradation factors. A suitable six parameter equation obtained by a current-pulse method, obtainable from MCFC's transient response in 100 ms, is expressible in an equivalent circuit composed of three sub-circuits. The relationship between these parameters and each degradation factor is evaluated by a single MCFC cell, the electrode area of which is 16 cm 2. Degradation factors include cross-leakage, electrolytic loss, cell temperature distribution and gas composition/flow rate. As a result, each of six parameters in the MCFC transient response corresponds to an ohmic potential drop, anode/cathode gas diffusion resistance, reactive resistance, three-phase interfacial resistance and electrolyte properties, respectively. The proposed performance diagnosis specifies the degradation factors by combining the six parameters. Performance diagnosis was applied to a single MCFC cell of an electrode area of 81 cm in extended operations, and the degradation factor diagnosed. As a result, the diagnosis was able to specify the cell degradation factors from the degradation factor ratio, corresponding to cell voltage, cell resistance and the N 2 concentration of MCFC single cell performance. Therefore, the proposed performance diagnosis is able to easily specify the driven MCFC degradation factors in a timely manner.

  15. Investigation of lasing in lead vapor by the double pulse method

    SciTech Connect

    Kazakov, V.V.; Markova, S.V.; Molchanova, L.V.; Petrash, G.G.

    1983-05-01

    The double pulse method was to study the 722.9 nm line emitted by a lead vapor laser. The parameters of the second excitation pulse were measured simultaneously with the lasing characteristics. It was found that the main factor determining a decrease in the laser output power in the second pulse was the residual population of the lower active level. Variations in the excitation pulse had a relatively weak influence on the form of this dependence and were essentially manifested when there was a relatively long delay between the excitation pulses.

  16. Method of estimating tissue attenuation using wideband ultrasonic pulse and apparatus for use therein

    SciTech Connect

    Flax, S.W.

    1986-11-11

    This patent describes a method of estimating tissue attenuation of ultrasound energy comprising the steps of: transmitting a wide band ultrasonic pulse into the tissue, the pulse having a frequency spectrum with a center frequency, detecting the pulse as reflected by the tissue, estimating decay of a measure of amplitude of the reflected pulse between two levels in the tissue to approximate the slope of the decay, estimating center frequency of the reflected pulse between the two levels, and obtaining tissue attenuation from the approximated slope of a measure of amplitude and the center frequency.

  17. New methods of generation of ultrashort laser pulses for ranging

    NASA Technical Reports Server (NTRS)

    Jelinkova, Helena; Hamal, Karel; Kubecek, V.; Prochazka, Ivan

    1993-01-01

    To reach the millimeter satellite laser ranging accuracy, the goal for nineties, new laser ranging techniques have to be applied. To increase the laser ranging precision, the application of the ultrashort laser pulses in connection with the new signal detection and processing techniques, is inevitable. The two wavelength laser ranging is one of the ways to measure the atmospheric dispersion to improve the existing atmospheric correction models and hence, to increase the overall system ranging accuracy to the desired value. We are presenting a review of several nonstandard techniques of ultrashort laser pulses generation, which may be utilized for laser ranging: compression of the nanosecond pulses using stimulated Brillouin and Raman backscattering; compression of the mode-locked pulses using Raman backscattering; passive mode-locking technique with nonlinear mirror; and passive mode-locking technique with the negative feedback.

  18. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    DOEpatents

    Smirl, Arthur; Trebino, Rick P.

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques.

  19. Spur decay kinetics of the solvated electron in heavy water radiolysis.

    SciTech Connect

    Bartels, D. M.; Gosztola, D.; Jonah, C. D.; Chemistry

    2001-08-30

    Spur decay kinetics of the hydrated electron following picosecond pulse radiolysis of heavy water have been measured using a time-correlated absorption spectroscopy (TCAS) technique. The TCAS data collected for the first 40 ns of the decay was matched up with single-shot transient digitizer data out to microsecond time scales. The decay shape in heavy water looks exactly like the decay in light water except in the first 10 ns. The 'time zero' solvated electron yield in heavy water radiolysis must be approximately 7% larger than in light water, to match the best available scavenger product measurements. We propose an explanation in terms of the larger distances traveled by electrons in heavy water prior to localization. The implication is that presolvated H{sub 2}O{sup +} 'holes' are very efficient scavengers for the presolvated conduction band electrons.

  20. Apparatus for and method of operating a cylindrical pulsed induction mass launcher

    DOEpatents

    Cowan, Jr., Maynard; Duggin, Billy W.; Widner, Melvin M.

    1992-01-01

    An electromagnetic cylindrical projectile mass launcher and a method of operation is provided which includes a cylindrical projectile having a conducting armature, a cylindrical barrel in which the armature is received, a plurality of electromagnetic drive coil stages, a plurality of pulse energy sources, and a pulsed power arrangement for generating magnetic pulses forming a pulsed magnetic wave along the length of the launcher barrel. The pulsed magnetic wave provides a propelling force on the projectile along the drive coil. The pulsed magnetic wave of the drive coil stages is advanced along the armature faster than the projectile to thereby generate an induced current wave in the armature. The pulsed generation of the magnetic wave minimizes electromagnetic heating of the projectile and provides for smooth acceleration of the projectile through the barrel of the launcher.

  1. Apparatus for and method of operating a cylindrical pulsed induction mass launcher

    DOEpatents

    Cowan, M. Jr.; Duggin, B.W.; Widner, M.M.

    1992-06-30

    An electromagnetic cylindrical projectile mass launcher and a method of operation is provided which includes a cylindrical projectile having a conducting armature, a cylindrical barrel in which the armature is received, a plurality of electromagnetic drive coil stages, a plurality of pulse energy sources, and a pulsed power arrangement for generating magnetic pulses forming a pulsed magnetic wave along the length of the launcher barrel. The pulsed magnetic wave provides a propelling force on the projectile along the drive coil. The pulsed magnetic wave of the drive coil stages is advanced along the armature faster than the projectile to thereby generate an induced current wave in the armature. The pulsed generation of the magnetic wave minimizes electromagnetic heating of the projectile and provides for smooth acceleration of the projectile through the barrel of the launcher. 2 figs.

  2. METHOD AND APPARATUS FOR PULSING A CHARGED PARTICLE BEAM

    DOEpatents

    Aaland, K.; Kuenning, R.W.; Harmon, R.K.

    1961-05-01

    A system is offered for pulsing a continuous beam of charged particles to form beam pulses that are consistently rectangular and of precise time durations which may be varied over an extremely wide range at a widely variable range of repetition rates. The system generally comprises spaced deflection plates on opposite sides of a beam axis in between which a unidirectional bias field is established to deflect the beam for impingement on an off-axis collector. The bias field is periodically neutralized by the application of fast rise time substantially rectangular pulses to one of the deflection plates in opposition to the bias field and then after a time delay to the other deflection plate in aiding relation to the bias field and during the flat crest portion of the bias opposing pulses. The voltage distribution of the resulting deflection field then includes neutral or zero portions which are of symmetrical substantially rectangular configuration relative to time and during which the beam axially passes the collector in the form of a substantially rectangular beam pulse.

  3. Method for generating high-energy and high repetition rate laser pulses from CW amplifiers

    DOEpatents

    Zhang, Shukui

    2013-06-18

    A method for obtaining high-energy, high repetition rate laser pulses simultaneously using continuous wave (CW) amplifiers is described. The method provides for generating micro-joule level energy in pico-second laser pulses at Mega-hertz repetition rates.

  4. Gamma Ray Radiolysis of the FPEX Solvent

    SciTech Connect

    B. J. Mincher; S. P. Mezyk; D. R. Peterman

    2006-09-01

    Slide presentation. FPEX contains a calixarene for Cs extraction, a crown ether for Sr extraction, Cs7SB modifier, and TOA to aid in stripping, in Isopar L diluent. The radiation stability FPEX must be evaluated prior to process use. Radiolytic degradation of species in solution are due to reaction with the direct radiolysis products of the diluent. In Isopar L, the reactive species produced include e-, •H and alkane radicals, resulting in a reducing environment. However, in nitric acid, oxidizing hydroxyl (•OH) and nitro (•NO2) radicals dominate system chemistry. Thus, the nature of diluent and the presence of radical scavengers affect the results of irradiation. We report the preliminary results of a new program to investigate the radiolysis of FPEX using the 60Co irradiation of FPEX neat solvent, acid pre-equilibrated solvent and mixed aerated phases. The Cs and Sr distribution ratios were used as metrics.

  5. Experimental validation of a high voltage pulse measurement method.

    SciTech Connect

    Cular, Stefan; Patel, Nishant Bhupendra; Branch, Darren W.

    2013-09-01

    This report describes X-cut lithium niobate's (LiNbO3) utilization for voltage sensing by monitoring the acoustic wave propagation changes through LiNbO3 resulting from applied voltage. Direct current (DC), alternating current (AC) and pulsed voltage signals were applied to the crystal. Voltage induced shift in acoustic wave propagation time scaled quadratically for DC and AC voltages and linearly for pulsed voltages. The measured values ranged from 10 - 273 ps and 189 ps - 2 ns for DC and non-DC voltages, respectively. Data suggests LiNbO3 has a frequency sensitive response to voltage. If voltage source error is eliminated through physical modeling from the uncertainty budget, the sensor's U95 estimated combined uncertainty could decrease to ~0.025% for DC, AC, and pulsed voltage measurements.

  6. Radiolysis of DNA-protein complexes

    NASA Astrophysics Data System (ADS)

    Běgusová, Marie; Gillard, Nathalie; Sy, Denise; Castaing, Bertrand; Charlier, Michel; Spotheim-Maurizot, Melanie

    2005-02-01

    We discuss here modifications of DNA and protein radiolysis due to the interaction of these two partners in specific complexes. Experimental patterns of frank strand breaks (FSB) and alkali revealed breaks (ARB) obtained for DNA lac operator bound to the lac repressor and for a DNA containing an abasic site analog bound to the formamidopyrimidine-DNA glycosylase are reported. Experimental data are compared to predicted damage distribution obtained using the theoretical model RADACK.

  7. Comparison of foot finding methods for deriving instantaneous pulse rates from photoplethysmographic signals.

    PubMed

    Hemon, Mathilde C; Phillips, Justin P

    2016-04-01

    The suitability of different methods of finding the foot point of a pulse as measured using earlobe photoplethysmography during stationary conditions was investigated. Instantaneous pulse period (PP) values from PPG signals recorded from the ear in healthy volunteer subjects were compared with simultaneous ECG-derived cardiac periods (RR interval). Six methods of deriving pulse period were used, each based on a different method of finding specific landmark points on the PPG waveform. These methods included maximum and minimum value, maximum first and second derivative, 'intersecting tangents' and 'diastole patching' methods. Selected time domain HRV variables were also calculated from the PPG signals obtained using multiple methods and compared with ECG-derived HRV variables. The correlation between PPG and ECG was greatest for the intersecting tangents method compared to the other methods (RMSE = 5.69 ms, r (2) = 0.997). No significant differences between PP and RR were seen for all PPG methods, however the PRV variables derived using all methods showed significant differences to HRV, attributable to the sensitivity of PRV parameters to pulse transients and artifacts. The results suggest that the intersecting tangents method shows the most promise for extracting accurate pulse rate variability data from PPG datasets. This work has applications in other areas where pulse arrival time is a key measurement including pulse wave velocity assessment. PMID:25902897

  8. Inconsistencies between two attosecond pulse metrology methods: A comparative study

    SciTech Connect

    Kruse, J. E.; Skantzakis, E.; Charalambidis, D.; Tzallas, P.; Kalpouzos, C.; Tsakiris, G. D.

    2010-08-15

    The two basic approaches underlying most of the metrology of attosecond pulse trains are compared in the spectral region {approx}14-24 eV, that is, the second-order intensity volume autocorrelation and the resolution of attosecond beating by interference of two photon transitions (RABITT). They give rather dissimilar pulse durations. It is concluded that for the present experimental conditions RABITT may underestimate the duration under measurement, due to variations of the driving intensity, but in conjunction with theory allows an estimation of the relative contributions of two different electron trajectories to the extreme-ultraviolet (XUV) radiation.

  9. Apparatus for and method of operating a cylindrical pulsed induction mass launcher

    SciTech Connect

    Cowan, M. Jr.; Duggin, B.W.; Widner, M.M.

    1990-12-06

    In accordance with the one aspect of the invention, an electromagnetic projectile launcher is provided which comprises: a conducting projectile, a barrel that receives the projectile, a plurality of electromagnetic drive coils, a plurality of pulsed energy sources, and pulse power means for generating a sequence of pulses forming a pulsed magnetic wave within the drive coil for propelling the projectile along the barrel, wherein the pulsed magnetic wave of the drive coil is advanced along the barrel faster than the projectile to thereby induce a current wave in the armature of the projectile and thereby minimize electromagnetic heating of the projectile and provide nearly constant acceleration of the projectile. In accordance with another aspect of the invention, a method is provided for propelling a projectile within a pulsed induction electromagnetic coil launcher, wherein the method comprises the steps of: generating a sequence of pulses forming a pulsed magnetic wave within the coil launcher, applying the pulsed magnetic wave initially at the aft end of the projectile to accelerate the projectile within the coil launcher, and advancing the position of the pulsed magnetic wave relative to the projectile to thereby generate an induced current wave in the armature, such that electromagnetic heating of the projectile is minimized and acceleration is nearly constant.

  10. Pulsed photoacoustic Doppler flowmetry using a cross correlation method

    NASA Astrophysics Data System (ADS)

    Brunker, J.; Beard, P.

    2010-02-01

    The feasibility of making spatially resolved measurements of blood flow using pulsed photoacoustic Doppler techniques has been explored. Doppler time shifts were quantified via cross-correlation of pairs of photoacoustic waveforms generated within a blood-simulating phantom using pairs of laser light pulses. The photoacoustic waves were detected using a focussed or planar PZT ultrasound transducer. This approach was found to be effective for quantifying the linear motion of micron-scale absorbers imprinted on an acetate sheet moving with velocities in the range 0.15 to 1.50 ms-1. The effect of the acoustic spot diameter and the time separation between the laser pulses on measurement resolution and the maximum measurable velocity is discussed. The distinguishing advantage of pulsed rather than continuous-wave excitation is that spatially resolved velocity measurements can be made. This offers the prospect of mapping flow within the microcirculation and thus providing insights into the perfusion of tumours and other pathologies characterised by abnormalities in flow status.

  11. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    DOEpatents

    Smirl, A.; Trebino, R.P.

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques. 2 figs.

  12. Method and apparatus for producing durationally short ultraviolet or x-ray laser pulses

    DOEpatents

    MacGowan, B.J.; Matthews, D.L.; Trebes, J.E.

    1987-05-05

    A method and apparatus is disclosed for producing ultraviolet or x- ray laser pulses of short duration. An ultraviolet or x-ray laser pulse of long duration is progressively refracted, across the surface of an opaque barrier, by a streaming plasma that is produced by illuminating a solid target with a pulse of conventional line focused high power laser radiation. The short pulse of ultraviolet or x-ray laser radiation, which may be amplified to high power, is separated out by passage through a slit aperture in the opaque barrier.

  13. Method and apparatus for producing durationally short ultraviolet or X-ray laser pulses

    DOEpatents

    MacGowan, Brian J.; Matthews, Dennis L.; Trebes, James E.

    1988-01-01

    A method and apparatus is disclosed for producing ultraviolet or X-ray laser pulses of short duration (32). An ultraviolet or X-ray laser pulse of long duration (12) is progressively refracted, across the surface of an opaque barrier (28), by a streaming plasma (22) that is produced by illuminating a solid target (16, 18) with a pulse of conventional line focused high power laser radiation (20). The short pulse of ultraviolet or X-ray laser radiation (32), which may be amplified to high power (40, 42), is separated out by passage through a slit aperture (30) in the opaque barrier (28).

  14. Method and apparatus for providing pulse pile-up correction in charge quantizing radiation detection systems

    DOEpatents

    Britton, Jr., Charles L.; Wintenberg, Alan L.

    1993-01-01

    A radiation detection method and system for continuously correcting the quantization of detected charge during pulse pile-up conditions. Charge pulses from a radiation detector responsive to the energy of detected radiation events are converted to voltage pulses of predetermined shape whose peak amplitudes are proportional to the quantity of charge of each corresponding detected event by means of a charge-sensitive preamplifier. These peak amplitudes are sampled and stored sequentially in accordance with their respective times of occurrence. Based on the stored peak amplitudes and times of occurrence, a correction factor is generated which represents the fraction of a previous pulses influence on a preceding pulse peak amplitude. This correction factor is subtracted from the following pulse amplitude in a summing amplifier whose output then represents the corrected charge quantity measurement.

  15. Method and apparatus for sputtering utilizing an apertured electrode and a pulsed substrate bias

    NASA Technical Reports Server (NTRS)

    Przybyszewski, J. S.; Shaltens, R. K. (Inventor)

    1973-01-01

    The method and equipment used for sputtering by use of an apertured electrode and a pulsed substrate bias are discussed. The technique combines the advantages of ion plating with the versatility of a radio frequency sputtered source. Electroplating is accomplished by passing a pulsed high voltage direct current to the article being plated during radio frequency sputtering.

  16. Concentrational oscillations of radiolysis products of concentrated solutions of MgCl/sub 2/

    SciTech Connect

    Grigor'ev, A.E.; Makarov, I.E.; Pikaev, A.K.

    1982-05-20

    The main end products of the radiolysis of concentrated MgCl/sub 2/ solutions are H/sub 2/ and so-called ''active chlorine,'' existing in three equilibrium forms: Cl/sub 3//sup -/, Cl/sub 2/, and HOCl. The predecessors of the active chlorine are ion-radicals Cl/sub 2//sup -/, which, as shown by the pulse radiolysis study, disappear in a second-order reaction accompanied by a symbatic increase in the optical absorption in 240-270 nm region. This absorption disappears for a few minutes, and the disappearance curve is 20-40% modulated by oscillations with a period of 2 min. The lifetime of the absorption and the oscillation amplitude are very dependent on the dose of the preliminary irradiation. Periodic oscillations are also observed on the accumulation curve of stable products during continuous irradiation by Bremsstrahlung from an electron beam on the Cockroft-Wolton accelerator. These concentrational oscillations are probably due to periodic oxidation-reduction processes, including the reactions between H/sub 2/O/sub 2/ and oxidized forms of chlorine, formed during the radiolysis of MgCl/sub 2/ solution.

  17. Method and apparatus for electrical cable testing by pulse-arrested spark discharge

    DOEpatents

    Barnum, John R.; Warne, Larry K.; Jorgenson, Roy E.; Schneider, Larry X.

    2005-02-08

    A method for electrical cable testing by Pulse-Arrested Spark Discharge (PASD) uses the cable response to a short-duration high-voltage incident pulse to determine the location of an electrical breakdown that occurs at a defect site in the cable. The apparatus for cable testing by PASD includes a pulser for generating the short-duration high-voltage incident pulse, at least one diagnostic sensor to detect the incident pulse and the breakdown-induced reflected and/or transmitted pulses propagating from the electrical breakdown at the defect site, and a transient recorder to record the cable response. The method and apparatus are particularly useful to determine the location of defect sites in critical but inaccessible electrical cabling systems in aging aircraft, ships, nuclear power plants, and industrial complexes.

  18. Increasing PCB Radiolysis Rates in Transformer Oil

    SciTech Connect

    Mincher, Bruce Jay

    2002-11-01

    The kinetics of Aroclor 1242 radiolysis in transformer oil, using high-energy electrons, was found to be analogous to that previously measured for individual polychlorinated biphenyl (PCB) congeners irradiated with ó-rays. The plot of the pseudo-first-order rate constant for PCB decomposition versus initial PCB concentration is a power function, with high rate constants for low concentrations. The addition of alkaline isopropanol to transformer oil was found to increase the pseudo-first-order rate constant for PCB decomposition. The rate constant under these conditions is independent of concentration. This may be explained by the establishment of chain reaction dechlorination in the oil.

  19. Increasing PCB radiolysis rates in transformer oil

    NASA Astrophysics Data System (ADS)

    Mincher, Bruce J.; Brey, Richard R.; Rodriguez, René G.; Pristupa, Scott; Ruhter, Aaron

    2002-11-01

    The kinetics of Aroclor 1242 radiolysis in transformer oil, using high-energy electrons, was found to be analogous to that previously measured for individual polychlorinated biphenyl (PCB) congeners irradiated with γ-rays. The plot of the pseudo-first-order rate constant for PCB decomposition versus initial PCB concentration is a power function, with high rate constants for low concentrations. The addition of alkaline isopropanol to transformer oil was found to increase the pseudo-first-order rate constant for PCB decomposition. The rate constant under these conditions is independent of concentration. This may be explained by the establishment of chain reaction dechlorination in the oil.

  20. Radiolysis of aqueous solutions of thiamine

    NASA Astrophysics Data System (ADS)

    Chijate, C.; Albarran, G.; Negron-Mendoza, A.

    1998-06-01

    The results of the radiolysis of aqueous solutions of thiamine (vitamin B 1) are presented. The yields for decomposition of thiamine and the product of radiolytic products were determined. The G values decrease as the dose increases. Some radiolytic products were identified. Decomposition of thiamine was slightly dependent on the presence of oxygen and on the pH of the solution. At pH 4.4 with a concentration of 2.5 × 10 -4 mol L -1 of thiamine in an oxygen free aqueous solution, the G 0 value for decomposition is 5.0.

  1. A noninvasive method to estimate pulse wave velocity in arteries locally by means of ultrasound.

    PubMed

    Brands, P J; Willigers, J M; Ledoux, L A; Reneman, R S; Hoeks, A P

    1998-11-01

    Noninvasive evaluation of vessel wall properties in humans is hampered by the absence of methods to assess directly local distensibility, compliance, and Young's modulus. Contemporary ultrasound methods are capable of assessing end-diastolic artery diameter, the local change in artery diameter as a function of time, and local wall thickness. However, to assess vessel wall properties of the carotid artery, for example, the pulse pressure in the brachial artery still must be used as a substitute for local pulse pressure. The assessment of local pulse wave velocity as described in the present article provides a direct estimate of local vessel wall properties (distensibility, compliance, and Young's modulus) and, in combination with the relative change in artery cross-sectional area, an estimate of the local pulse pressure. The local pulse wave velocity is obtained by processing radio frequency ultrasound signals acquired simultaneously along two M-lines spaced at a known distance along the artery. A full derivation and mathematical description of the method to assess local pulse wave velocity, using the temporal and longitudinal gradients of the change in diameter, are presented. A performance evaluation of the method was carried out by means of experiments in an elastic tube under pulsatile pressure conditions. It is concluded that, in a phantom set-up, the assessed local pulse wave velocity provides reliable estimates for local distensibility. PMID:10385955

  2. Pulsed-injection method for blood flow velocity measurement in intraarterial digital subtraction angiography.

    PubMed

    Shaw, C G; Plewes, D B

    1986-08-01

    The pulsed-injection method for measuring the velocity of blood flow in intraarterial digital subtraction angiography is described. With this technique, contrast material is injected at a pulsing frequency as high as 15 Hz, so that two or more boluses can be imaged simultaneously. The velocity of flow is determined by measuring the spacing between the boluses and multiplying it by the pulsing frequency. Results of tests with phantoms correlate well with flow measurements obtained with a graduated cylinder for velocities ranging from 8 to 60 cm/sec. The potential of the method for time-dependent velocity measurement has been demonstrated with simulated pulsatile flows. PMID:3523598

  3. A method for pressure-pulse suppression in fluid-filled piping

    SciTech Connect

    Shin, Y.W.; Bielick, E.F. ); Wiedermann, A.H. ); Ockert, C.E. )

    1989-01-01

    A simple, nondestructive method to suppress pressure pulses in fluid-filled piping was proposed and theoretically analyzed earlier. In this paper, the proposed method is verified experimentally. The results of experiments performed for the range of parameters of practical importance indicated that the attenuation of pressure pulses was in accordance with the theoretical predictions. This paper describes the experimental setup and the test models of the proposed pulse suppression devices and discusses the experimental results. In particular, the measured attenuation factors are presented and compared with the theoretical predictions. 8 ref., 17 fig., 2 tab.

  4. Radiolysis of the polyethylene/water system: Studies on the role of hydroxyl radical

    NASA Astrophysics Data System (ADS)

    Billamboz, Nicolas; Grivet, Manuel; Foley, Sarah; Baldacchino, Gérard; Hubinois, Jean-Charles

    2010-01-01

    The role of hydroxyl radical on polyethylene degradation under aqueous conditions has been studied. The reactivity of HO· towards PE is highlighted by pulse radiolysis experiments on a PE powder suspension in water using the thiocyanate competition technique. Infrared analysis of PE films irradiated in the presence of water is performed. Solutions have been either degassed with Ar, in order to remove O 2 which would react with the PE, or N 2O which enhances the production of HO· radicals. Oxygenated groups and double bond groups created at the surface of PE are characterized using IR analysis, and the results for both saturated solution systems are compared.

  5. Reverse current pulse method to restore uniform concentration profiles in ion-selective membranes. Part I: Galvanostatic pulse methods with decreased cycle time

    PubMed Central

    Zook, Justin M.; Lindner, Ernő

    2009-01-01

    The applications of ion-selective electrodes (ISEs) have been broadened through the introduction of galvanostatic current pulse methods in potentiometric analysis. An important requirement in these applications is the restoration of the uniform equilibrium concentration profiles in the ISE membrane between each measurement. The simplest restoration method is zero current relaxation, in which the membrane relaxes under open-circuit conditions in a diffusion-controlled process. This paper presents a novel restoration method using a reverse current pulse. An analytic model for this restoration method is derived to predict the concentration profiles inside ISE membranes following galvanostatic current pulses. This model allows the calculation of the voltage transients as the membrane voltage relaxes back towards its zero-current equilibrium value. The predicted concentration profiles and voltage transients are confirmed using spectroelectrochemical microscopy (SpECM). The reverse current restoration method described in this paper reduces the voltage drift and voltage error by 10 to 100 times compared to the zero current restoration method. Therefore, this new method provides faster and more reproducible voltage measurements in most chronopotentiometric ISE applications, such as improving the detection limit and determining concentrations and diffusion coefficients of membrane species. One limitation of the reverse current restoration method is that it cannot be used in a few applications that require background electrolyte loaded membranes without excess of lipophilic cation exchanger. PMID:19459603

  6. Production of pulsed atomic oxygen beams via laser vaporization methods

    NASA Technical Reports Server (NTRS)

    Brinza, David E.; Coulter, Daniel R.; Liang, Ranty H.; Gupta, Amitava

    1986-01-01

    The generation of energetic pulsed atomic oxygen beams by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin indium-tin oxide (ITO) films is reported. Mass spectroscopy is used in the mass and energy characterization of beams from the ozone/oxygen films, and a peak flux of 3 x 10 to the 20th/sq m per sec at 10 eV is found. Analysis of the time-of-flight data suggests that several processes contribute to the formation of the oxygen beam. Results show the absence of metastable states such as the 2p(3)3s(1)(5S) level of atomic oxygen blown-off from the ITO films. The present process has application to the study of the oxygen degradation problem of LEO materials.

  7. Pulsed voltage electrospray ion source and method for preventing analyte electrolysis

    SciTech Connect

    Kertesz, Vilmos; Van Berkel, Gary

    2011-12-27

    An electrospray ion source and method of operation includes the application of pulsed voltage to prevent electrolysis of analytes with a low electrochemical potential. The electrospray ion source can include an emitter, a counter electrode, and a power supply. The emitter can include a liquid conduit, a primary working electrode having a liquid contacting surface, and a spray tip, where the liquid conduit and the working electrode are in liquid communication. The counter electrode can be proximate to, but separated from, the spray tip. The power system can supply voltage to the working electrode in the form of a pulse wave, where the pulse wave oscillates between at least an energized voltage and a relaxation voltage. The relaxation duration of the relaxation voltage can range from 1 millisecond to 35 milliseconds. The pulse duration of the energized voltage can be less than 1 millisecond and the frequency of the pulse wave can range from 30 to 800 Hz.

  8. Production of pulsed atomic oxygen beams via laser vaporization methods

    NASA Technical Reports Server (NTRS)

    Brinza, David E.; Coulter, Daniel R.; Liang, Ranty H.; Gupta, Amitava

    1987-01-01

    Energetic pulsed atomic oxygen beams were generated by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin films of indium-tin oxide (ITO). Mass and energy characterization of beams from the ozone/oxygen films were carried out by mass spectrometry. The peak flux, found to occur at 10 eV, is estimated from this data to be 3 x 10(20) m(-2) s(-1). Analysis of the time-of-flight data indicates a number of processes contribute to the formation of the atomic oxygen beam. The absence of metastable states such as the 2p(3) 3s(1) (5S) level of atomic oxygen blown off from ITO films is supported by the failure to observe emission at 777.3 nm from the 2p(3) 3p(1) (5P sub J) levels. Reactive scattering experiments with polymer film targets for atomic oxygen bombardment are planned using a universal crossed molecular beam apparatus.

  9. Reaction mechanisms in the radiolysis of peptides, polypeptides, and proteins. I. Reactions of the peptide main-chain in model systems

    SciTech Connect

    Garrison, W.M.

    1982-08-01

    The object of this review is to bring together and to correlate our present knowledge of products and mechanisms in the radiolysis of peptides, polypeptides and proteins in both aqueous and solid-state systems. Results obtained with various experimental techniques such as product analysis, competition kinetics, ESR spectroscopy and pulse radiolysis are included. Here in part I the emphasis is on the various radiation-induced reactions of the peptide main-chain in model systems. In part II the emphasis is on the radiation chemistry of side-chain loci of the aliphatic, sulfur-containing, aromatic and other unsaturated amino acid residues in similar systems. And, in part III this information on model systems is used in interpreting the mechanisms of chemical change in the radiolysis of proteins in aqueous solution and in the solid state. 60 references.

  10. Green function method for the time domain simulation of pulse propagation.

    PubMed

    Huang, Jing; Yao, Jianquan; Xu, Degang; Li, Runhua

    2014-06-01

    Based on the Green function method, the nonlinear Schrödinger equation is directly solved in the time domain (without Fourier transform). Because the dispersion and nonlinear effects are calculated simultaneously, it does not bring any spurious effect such as the split-step method in which the step size has to be carefully controlled by an error estimation. By this time domain solution, the pulse fission is analyzed, and we obtain the relationship between the minimum T₀ (the half-width at 1/e-intensity point of a pulse) and dispersion coefficients (β₂, β₃, and β₄). Thus the concrete dispersion values, which have an impact on ultrashort pulses (the quantity units is femtosecond or attosecond), are listed. It has been demonstrated that pulse fission occurs in the normal and anomalous dispersion regimes, even though fourth-order dispersion and the fifth-order nonlinear effects are not taken into account. PMID:24922431

  11. Evaluation of the pulse-contour method of determining stroke volume in man.

    NASA Technical Reports Server (NTRS)

    Alderman, E. L.; Branzi, A.; Sanders, W.; Brown, B. W.; Harrison, D. C.

    1972-01-01

    The pulse-contour method for determining stroke volume has been employed as a continuous rapid method of monitoring the cardiovascular status of patients. Twenty-one patients with ischemic heart disease and 21 patients with mitral valve disease were subjected to a variety of hemodynamic interventions. The pulse-contour estimations, using three different formulas derived by Warner, Kouchoukos, and Herd, were compared with indicator-dilution outputs. A comparison of the results of the two methods for determining stroke volume yielded correlation coefficients ranging from 0.59 to 0.84. The better performing Warner formula yielded a coefficient of variation of about 20%. The type of hemodynamic interventions employed did not significantly affect the results using the pulse-contour method. Although the correlation of the pulse-contour and indicator-dilution stroke volumes is high, the coefficient of variation is such that small changes in stroke volume cannot be accurately assessed by the pulse-contour method. However, the simplicity and rapidity of this method compared to determination of cardiac output by Fick or indicator-dilution methods makes it a potentially useful adjunct for monitoring critically ill patients.

  12. Radiolysis Concerns for Water Shielding in Fission Surface Power Applications

    SciTech Connect

    Schoenfeld, Michael P.; Anghaie, Samim

    2008-01-21

    This paper presents an overview of radiolysis concerns with regard to water shields for fission surface power. A review of the radiolysis process is presented and key parameters and trends are identified. From this understanding of the radiolytic decomposition of water, shield pressurization and corrosion are identified as the primary concerns. Existing experimental and modeling data addressing concerns are summarized. It was found that radiolysis of pure water in a closed volume results in minimal, if any net decomposition, and therefore reduces the potential for shield pressurization and corrosion.

  13. Radiolysis Model Sensitivity Analysis for a Used Fuel Storage Canister

    SciTech Connect

    Wittman, Richard S.

    2013-09-20

    This report fulfills the M3 milestone (M3FT-13PN0810027) to report on a radiolysis computer model analysis that estimates the generation of radiolytic products for a storage canister. The analysis considers radiolysis outside storage canister walls and within the canister fill gas over a possible 300-year lifetime. Previous work relied on estimates based directly on a water radiolysis G-value. This work also includes that effect with the addition of coupled kinetics for 111 reactions for 40 gas species to account for radiolytic-induced chemistry, which includes water recombination and reactions with air.

  14. A simple and robust method to study after-pulses in Silicon Photomultipliers

    NASA Astrophysics Data System (ADS)

    Caccia, M.; Santoro, R.; Stanizzi, G. A.

    2014-10-01

    The after-pulsing probability in Silicon Photomultipliers and its time constant are obtained measuring the mean number of photo-electrons in a variable time window following a light pulse. The method, experimentally simple and statistically robust due to the use of the Central Limit Theorem, has been qualified applying it to an HAMAMATSU Multi Pixel Photon Counter (MPPC) S10362-11-100C.

  15. A Pulse-Compression Method for Process Monitoring

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva; Wang, Xiaoxia

    2000-01-01

    This paper describes, from a deterministic view point, an on-line process monitoring method for small signal behavior of time invariant stable systems at a given operating point. The monitoring is accomplished by using an consequence modulated low-pass wavelet as the probing signal, and a cyclic reference signal as the correlator. This method allows to achieve high resolution, high signal to noise ratio monitoring, and the acquired data can be used for on-line diagnosis.

  16. Scintillation event energy measurement via a pulse model based iterative deconvolution method

    NASA Astrophysics Data System (ADS)

    Deng, Zhenzhou; Xie, Qingguo; Duan, Zhiwen; Xiao, Peng

    2013-11-01

    This work focuses on event energy measurement, a crucial task of scintillation detection systems. We modeled the scintillation detector as a linear system and treated the energy measurement as a deconvolution problem. We proposed a pulse model based iterative deconvolution (PMID) method, which can process pileup events without detection and is adaptive for different signal pulse shapes. The proposed method was compared with digital gated integrator (DGI) and digital delay-line clipping (DDLC) using real world experimental data. For singles data, the energy resolution (ER) produced by PMID matched that of DGI. For pileups, the PMID method outperformed both DGI and DDLC in ER and counts recovery. The encouraging results suggest that the PMID method has great potentials in applications like photon-counting systems and pulse height spectrometers, in which multiple-event pileups are common.

  17. The Radiolysis of AmVI Solutions

    SciTech Connect

    Bruce J. Mincher

    2013-06-01

    The reduction of bismuthate-produced AmVI by 60Co gamma-rays was measured using post-irradiation UV/Vis spectroscopy. The reduction of AmVI by radiolysis was rapid, producing AmV as the sole product. Relatively low absorbed doses in the ~0.3 kGy range quantitatively reduced a solution of 2.5 x 10-4 M AmVI. The addition of bismuthate to samples during irradiation did not appear to protect AmVI from radiolytic reduction during these experiments. It was also shown here that AmV is very stable toward radiation. The quantitative reduction of the AmVI concentration here corresponds to 1.4 hours of exposure to a process solution, however the actual americium concentrations will be higher and the expected contact times short when using centrifugal contactors. Thus, the reduction rate found in these initial experiments may not be excessive.

  18. Radiolysis: Icy Satellite Atmospheres and Surface Aging

    NASA Astrophysics Data System (ADS)

    Johnson, R. E.; Carlson, R. W.; Leblanc, F.; Shematovich, V. I.

    2001-11-01

    The jovian trapped particle radiation chemically alters the Galilean satellite surfaces, a process referred to as radiolysis. This leads to the chemical alteration and decomposition of the surface materials and the production of volatiles (Johnson 2001). Radiolysis likely accounts for the darkening of the polar regions of Io (Johnson 1997), the O2 (Calvin et al 1996), peroxide (Carlson et al 1999a) and, possibly, O3 (Noll et al 1996) in icy satellite surfaces, the radiolytic sulfur cycle on Europa (Carlson et al 1999b), the production of O2 (Hall et al. 1995) and alkali atmospheres (Brown and Hill, 1996) and, possibly, the production of the CO2 atmosphere at Callisto (Carlson 1999). Results for the radiolytic processing of likely surface materials will be used to create atmospheric models and to describe surface aging. Emphasis will be on Europa's surface and atmosphere. Brown, M.E. and R.E. Hill Nature 380,229(1996) Calvin, W., et al. GRL 23, 673(1996) Carlson, R.W., Science 283,820(1999) Carlson, R.W. et al., Science 286, 97(1999a) Carlson, R.W., et al. Science 283, 2062(1999b Hall, D.T. et al. Nature 373, 677(1995) Johnson, R.E., Icarus 128, 469 (1997) 469- 471. Johnson, R.E., et al., GRL 25, 3257(1998) Johnson, R.E., In,Chemical Dynamics in Extreme Environments (R.Dessler,Ed)390 (2001) Noll, K.S. et al., Science 273, 607(1996)

  19. Facile time-of-flight methods for characterizing pulsed superfluid helium droplet beams

    NASA Astrophysics Data System (ADS)

    He, Yunteng; Zhang, Jie; Li, Yang; Freund, William M.; Kong, Wei

    2015-08-01

    We present two facile time-of-flight (TOF) methods of detecting superfluid helium droplets and droplets with neutral dopants. Without an electron gun and with only a heated filament and pulsed electrodes, the electron impact ionization TOF mass spectrometer can resolve ionized helium clusters such as He2+ and He4+, which are signatures of superfluid helium droplets. Without ionizing any helium atoms, multiphoton non-resonant laser ionization of CCl4 doped in superfluid helium droplets at 266 nm generates complex cluster ions of dopant fragments with helium atoms, including (He)nC+, (He)nCl+, and (He)nCCl+. Using both methods, we have characterized our cryogenic pulsed valve—the Even-Lavie valve. We have observed a primary pulse with larger helium droplets traveling at a slower speed and a rebound pulse with smaller droplets at a faster speed. In addition, the pickup efficiency of dopant is higher for the primary pulse when the nozzle temperature is higher than 13 K, and the total time duration of the doped droplet pulse is only on the order of 20 μs. These results stress the importance of fast and easy characterization of the droplet beam for sensitive measurements such as electron diffraction of doped droplets.

  20. Facile time-of-flight methods for characterizing pulsed superfluid helium droplet beams

    SciTech Connect

    He, Yunteng; Zhang, Jie; Li, Yang; Freund, William M.; Kong, Wei

    2015-08-15

    We present two facile time-of-flight (TOF) methods of detecting superfluid helium droplets and droplets with neutral dopants. Without an electron gun and with only a heated filament and pulsed electrodes, the electron impact ionization TOF mass spectrometer can resolve ionized helium clusters such as He{sub 2}{sup +} and He{sub 4}{sup +}, which are signatures of superfluid helium droplets. Without ionizing any helium atoms, multiphoton non-resonant laser ionization of CCl{sub 4} doped in superfluid helium droplets at 266 nm generates complex cluster ions of dopant fragments with helium atoms, including (He){sub n}C{sup +}, (He){sub n}Cl{sup +}, and (He){sub n}CCl{sup +}. Using both methods, we have characterized our cryogenic pulsed valve—the Even-Lavie valve. We have observed a primary pulse with larger helium droplets traveling at a slower speed and a rebound pulse with smaller droplets at a faster speed. In addition, the pickup efficiency of dopant is higher for the primary pulse when the nozzle temperature is higher than 13 K, and the total time duration of the doped droplet pulse is only on the order of 20 μs. These results stress the importance of fast and easy characterization of the droplet beam for sensitive measurements such as electron diffraction of doped droplets.

  1. [Research on the Method of Blood Pressure Monitoring Based on Multiple Parameters of Pulse Wave].

    PubMed

    Miao, Changyun; Mu, Dianwei; Zhang, Cheng; Miao, Chunjiao; Li, Hongqiang

    2015-10-01

    In order to improve the accuracy of blood pressure measurement in wearable devices, this paper presents a method for detecting blood pressure based on multiple parameters of pulse wave. Based on regression analysis between blood pressure and the characteristic parameters of pulse wave, such as the pulse wave transit time (PWTT), cardiac output, coefficient of pulse wave, the average slope of the ascending branch, heart rate, etc. we established a model to calculate blood pressure. For overcoming the application deficiencies caused by measuring ECG in wearable device, such as replacing electrodes and ECG lead sets which are not convenient, we calculated the PWTT with heart sound as reference (PWTT(PCG)). We experimentally verified the detection of blood pressure based on PWTT(PCG) and based on multiple parameters of pulse wave. The experiment results showed that it was feasible to calculate the PWTT from PWTT(PCG). The mean measurement error of the systolic and diastolic blood pressure calculated by the model based on multiple parameters of pulse wave is 1.62 mm Hg and 1.12 mm Hg, increased by 57% and 53% compared to those of the model based on simple parameter. This method has more measurement accuracy. PMID:26964321

  2. Facile time-of-flight methods for characterizing pulsed superfluid helium droplet beams.

    PubMed

    He, Yunteng; Zhang, Jie; Li, Yang; Freund, William M; Kong, Wei

    2015-08-01

    We present two facile time-of-flight (TOF) methods of detecting superfluid helium droplets and droplets with neutral dopants. Without an electron gun and with only a heated filament and pulsed electrodes, the electron impact ionization TOF mass spectrometer can resolve ionized helium clusters such as He2(+) and He4(+), which are signatures of superfluid helium droplets. Without ionizing any helium atoms, multiphoton non-resonant laser ionization of CCl4 doped in superfluid helium droplets at 266 nm generates complex cluster ions of dopant fragments with helium atoms, including (He)(n)C(+), (He)(n)Cl(+), and (He)(n)CCl(+). Using both methods, we have characterized our cryogenic pulsed valve—the Even-Lavie valve. We have observed a primary pulse with larger helium droplets traveling at a slower speed and a rebound pulse with smaller droplets at a faster speed. In addition, the pickup efficiency of dopant is higher for the primary pulse when the nozzle temperature is higher than 13 K, and the total time duration of the doped droplet pulse is only on the order of 20 μs. These results stress the importance of fast and easy characterization of the droplet beam for sensitive measurements such as electron diffraction of doped droplets. PMID:26329210

  3. Heterogeneous radiolysis of CO 2 in the presence of zeolites

    NASA Astrophysics Data System (ADS)

    Garibov, A. A.; Velibekova, G. Z.; Agayev, T. N.

    Radiation catalytic activity of different zeolites Ca A, Na X, Na Y, LiNa Y, Ba M in CO 2 radiolysis has been investigated. This has led to studies in the catalyst porosity, the number of adsorbed CO 2 molecules and adsorption forces on their surface on the yield of CO 2 radiolysis products. A mechanism has been suggested for the observed CO 2 radiolysis processes over different zeolites. One of the possible ways to increase CO yield in radiolytic processes of CO 2 decomposition is to use various types of catalyst. (1-3) Therefore, the development of a scientific basis for appropriate catalyst selection is becoming of particular interest. For this purpose, heterogeneous CO 2 radiolysis in the presence of high-silica zeolites has been studied in this paper.

  4. The Radiolysis and Radioracemization of Amino Acids on Silica Surfaces

    NASA Astrophysics Data System (ADS)

    Bonner, William A.; Lemmon, Richard M.

    1981-12-01

    L-Leucine, deposited on both 1-quartz powder and on a commercial amorphous silica preparation (Syloid 63), has been subjected to irradiation in a60Co γ-ray source, and the ensuing radiolysis and radioracemization have been determined gas chromatographically. The radiolysis and radioracemization observed for leucine on 1-quartz were rather similar to those noted for a crystalline L-leucine control. L-Leucine on Syloid 63, however, was vastly more susceptible to radiolysis as compared to the L-leucine control, and radioracemization was also markedly enhanced—each increasing with larger radiation dosage. L-Isovaline showed a similar, but diminished, enhancement of radiolysis sensitivity when adsorbed on the Syloid surface, but underwent no radioracemization whatsoever. The divergent results of the control and quartz-leucine irradiationsversus the Syloid-leucine and Syloid-isovaline irradiations are interpreted qualitatively in terms of the surface area parameters of the two silica adsorbents and the amino acid adsorbates.

  5. Pulse Shape Discrimination and Classification Methods for Continuous Depth of Interaction Encoding PET Detectors

    PubMed Central

    Roncali, Emilie; Phipps, Jennifer E.; Marcu, Laura; Cherry, Simon R.

    2012-01-01

    In previous work we demonstrated the potential of positron emission tomography (PET) detectors with depth-of-interaction (DOI) encoding capability based on phosphor-coated crystals. A DOI resolution of 8 mm full-width at half-maximum was obtained for 20 mm long scintillator crystals using a delayed charge integration linear regression method (DCI-LR). Phosphor-coated crystals modify the pulse shape to allow continuous DOI information determination, but the relationship between pulse shape and DOI is complex. We are therefore interested in developing a sensitive and robust method to estimate the DOI. Here, linear discriminant analysis (LDA) was implemented to classify the events based on information extracted from the pulse shape. Pulses were acquired with 2 × 2 × 20 mm3 phosphor-coated crystals at five irradiation depths and characterized by their DCI values or Laguerre coefficients. These coefficients were obtained by expanding the pulses on a Laguerre basis set and constituted a unique signature for each pulse. The DOI of individual events was predicted using LDA based on Laguerre coefficients (Laguerre-LDA) or DCI values (DCI-LDA) as discriminant features. Predicted DOIs were compared to true irradiation depths. Laguerre-LDA showed higher sensitivity and accuracy than DCI-LDA and DCI-LR and was also more robust to predict the DOI of pulses with higher statistical noise due to low light levels (interaction depths further from the photodetector face). This indicates that Laguerre-LDA may be more suitable to DOI estimation in smaller crystals where lower collected light levels are expected. This novel approach is promising for calculating DOI using pulse shape discrimination in single-ended readout depth-encoding PET detectors. PMID:23010690

  6. PASTEURIZATION USING A LENS AND SOLAR ENERGY (PULSE) METHOD

    EPA Science Inventory

    Water pasteurization using Fresnel lenses and preexisting solar disinfection methods will be evaluated. Preliminary tests were conducted using two types of Fresnel lenses: spot and linear, which concentrate solar energy onto a point and a line respectively on a water contai...

  7. Selecting ethanol as a model organic solvent in radiation chemistry—I. Radiolysis of acetone-ethanol system

    NASA Astrophysics Data System (ADS)

    Haofang, Jin; Jilan, Wu; Xianming, Pan; Xujia, Zhang

    1996-04-01

    Radiolysis of acetone-ethanol solution [Zhang, Wu and Zhou (1994) Radiat. Phys. Chem.43, 335] has been further studied in this work. The dependences of G values of the final γ radiolytic products such as H 2, 2,3-butanediol and acetaldehyde on acetone concentrations in liquid ethanol were obtained. New information was provided that except the detected new product 2-methyl-2,3-butanedio (Zhang et al., 1994), another new final product isopropanol was also found and material balance between intermediates and major final products was obtained. In addition, a ratio of rate constants k(e s- + CH 3CHO)/ k(e s- + CH 3COCH 3) = 0.96 was calculated by computer simulation, which is in good agreement with the result obtained from pulse radiolysis experiments [Milinchuk and Tupikov (1989) Organic Radiation Chemistry Handbook].

  8. A Target Indirect Thrust Measurement Method of Pulse Detonation Engine

    NASA Astrophysics Data System (ADS)

    Huang, Xiqiao; Xiong, Yuefei; Li, Chao; Zheng, Longxi; Li, Qing

    2015-05-01

    An indirect thrust measurement method based on impulse of a target plate was developed, and a new thrust measurement system (TMS) was successfully designed and constructed. A series of multi-cycle experiments on thrust measurement were conducted to investigate the feasibility of this method with the newly-built indirect TMS. The thrust measurement of PDE was made at different plate target axial positions and operating frequencies. All the experiments were conducted using gasoline as fuel and air as oxidant. The experimental results implied that the thrust of PDE by using the indirect impulse method was a function of the target plate axial position, and there existed an optimum measurement position for PDE with a diameter of 60 mm. The optimum target plate position located at 3.33. According to the experimental results, the thrusts obtained by using indirect TMS were less than the actual values, and so the observed value of thrust was modified in order to make the thrust more reliable. A relative accurate calibration formula depending on the operating frequency was found.

  9. The radiolysis and radioracemization of amino acids on clays

    NASA Technical Reports Server (NTRS)

    Bonner, W. A.; Hall, H.; Chow, G.; Yi, L.; Lemmon, R. M.

    1985-01-01

    The effects of the surfaces of kaolinite and bentonite clays on the radiolysis and radioracemization of L-leucine and its hydrochloride salt have been investigated experimentally. L-leucine and its hydrochloride salt were deposited on the clays and the amino acid/clay preparations were irradiated by a Co-60 gamma-ray source which induced 2-89 percent radiolysis. The efficiency of radiolysis and radioracemization were measured using gas chromatography. Results were obtained for leucine in 0.1 M aqueous solution for comparison with the clay-deposted leucine and leucine hydrochloride. It is found that radiolysis and radioracemization in the samples occurred according to a pseudo-first-order rate law. Comparison of the specific rate constants showed that leucine and its hydrochloride salt were the most resistant to both radiolysis and radioracemization, followed by leucine and its hydrochloride salt on kaolin. Leucine and its HCl salt on bentonite, and leucine in aqueous solution were found to be the least resistant to radiolysis and radioracemization. The experimental results are intepreted with respect to the Vester-Ulbricht mechanism for the origin of optical activity.

  10. Terahertz pulsed imaging in vivo: measurements and processing methods

    NASA Astrophysics Data System (ADS)

    Parrott, Edward P. J.; Sy, Stanley M. Y.; Blu, Thierry; Wallace, Vincent P.; Pickwell-MacPherson, Emma

    2011-10-01

    This paper presents a number of data processing algorithms developed to improve the accuracy of results derived from datasets acquired by a recently designed terahertz handheld probe. These techniques include a baseline subtraction algorithm and a number of algorithms to extract the sample impulse response: double Gaussian inverse filtering, frequency-wavelet domain deconvolution, and sparse deconvolution. In vivo measurements of human skin are used as examples, and a comparison is made of the terahertz impulse response from a number of different skin positions. The algorithms presented enables both the spectroscopic and time domain properties of samples measured in reflection geometry to be better determined compared to previous calculation methods.

  11. Noninvasive Method for Measuring Local Pulse Wave Velocity by Dual Pulse Wave Doppler: In Vitro and In Vivo Studies

    PubMed Central

    Wang, Zhen; Yang, Yong; Yuan, Li-jun; Liu, Jie; Duan, Yun-you; Cao, Tie-sheng

    2015-01-01

    Objectives To evaluate the validity and reproducibility of a noninvasive dual pulse wave Doppler (DPWD) method, which involves simultaneous recording of flow velocity of two independent sample volumes with a measurable distance, for measuring the local arterial pulse wave velocity (PWV) through in vitro and in vivo studies. Methods The DPWD mode of Hitachi HI Vision Preirus ultrasound system with a 5–13MHz transducer was used. An in vitro model was designed to compare the PWV of a homogeneous rubber tubing with the local PWV of its middle part measured by DPWD method. In the in vivo study, local PWV of 45 hypertensive patients (25 male, 49.8±3.1 years) and 45 matched healthy subjects (25 male, 49.3±3.0 years) were investigated at the left common carotid artery (LCCA) by DPWD method. Results In the in vitro study, the local PWV measured by DPWP method and the PWV of the homogeneous rubber tubing did not show statistical difference (5.16 ± 0.28 m/s vs 5.03 ± 0.15 m/s, p = 0.075). The coefficient of variation (CV) of the intra- and inter- measurements for local PWV were 3.46% and 4.96%, for the PWV of the homogeneous rubber tubing were 0.99% and 1.98%. In the in vivo study, a significantly higher local PWV of LCCA was found in the hypertensive patients as compared to that in healthy subjects (6.29±1.04m/s vs. 5.31±0.72m/s, P = 0.019). The CV of the intra- and inter- measurements in hypertensive patients were 2.22% and 3.94%, in healthy subjects were 2.07% and 4.14%. Conclusions This study demonstrated the feasibility of the noninvasive DPWD method to determine the local PWV, which was accurate and reproducible not only in vitro but also in vivo studies. This noninvasive echocardiographic method may be illuminating to clinical use. PMID:25786124

  12. Method and apparatus for pulse width modulation control of an AC induction motor

    DOEpatents

    Geppert, Steven; Slicker, James M.

    1984-01-01

    An inverter is connected between a source of DC power and a three-phase AC induction motor, and a micro-processor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .THETA., where .THETA. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands of electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a "flyback" DC-DC converter circuit for recharging the battery.

  13. Method and apparatus for pulse width modulation control of an AC induction motor

    NASA Technical Reports Server (NTRS)

    Geppert, Steven (Inventor); Slicker, James M. (Inventor)

    1984-01-01

    An inverter is connected between a source of DC power and a three-phase AC induction motor, and a micro-processor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .THETA., where .THETA. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands of electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a flyback DC-DC converter circuit for recharging the battery.

  14. Determination of diffusion coefficients in polypyrrole thin films using a current pulse relaxation method

    NASA Technical Reports Server (NTRS)

    Penner, Reginald M.; Vandyke, Leon S.; Martin, Charles R.

    1987-01-01

    The current pulse E sub oc relaxation method and its application to the determination of diffusion coefficients in electrochemically synthesized polypyrrole thin films is described. Diffusion coefficients for such films in Et4NBF4 and MeCN are determined for a series of submicron film thicknesses. Measurement of the double-layer capacitance, C sub dl, and the resistance, R sub u, of polypyrrole thin films as a function of potential obtained with the galvanostatic pulse method is reported. Measurements of the electrolyte concentration in reduced polypyrrole films are also presented to aid in the interpretation of the data.

  15. Time resolved optical methods for investigation of phase transformations in materials exposed to nanosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Martan, J.; Semmar, N.; Cibulka, O.

    2011-06-01

    Infrared (IR) radiometry and time resolved reflectivity (TRR) methods can be used for investigation of laser pulse effects on materials in nanosecond time scale. The methods in combination are capable to quantify object temperature and detect phase transformations in the solid state, melting and plasma formation from vapour. Measurements with different laser pulse energy densities provide threshold of the transformation. The melt duration can be also determined. The experimental system is described. It contains KrF excimer laser with homogenizer and variable attenuator, fast IR detector for radiometry, continuous probing laser with Si photodiode for reflectivity measurement and UV detector for pump laser pulse reflection measurement. The system was applied to investigation of responses to laser light of silicon and different pure metals and alloys. The range of energy densities used was 1-5500 mJ.cm-2 and measurements were done with temporal resolution of 6 ns for radiometry and 1 ns for reflectivity.

  16. Littrow angle method to remove alignment errors in grating pulse compressors.

    PubMed

    Guardalben, M J

    2008-09-20

    An alignment method for pulse-compression gratings that obviates the need to place the gratings at normal incidence to remove grating-tip error is proposed. Grating-tip and groove-orientation errors are removed using two alignment wavelengths in a manner analogous to a laser-beam pointing and centering procedure entirely at the respective Littrow angles for the two wavelengths. By choosing wavelengths with Littrow angles close to the use angle of the grating, the residual tip and groove-orientation errors that may be introduced when the grating mount is tilted to its use angle are reduced. This method has greatly facilitated the alignment of the OMEGA Extended Performance (EP) large-aperture pulse compressors, thereby reducing residual pulse-front tilt caused by nonparallel gratings. OMEGA EP is a high-energy, petawatt-class laser at the University of Rochester's Laboratory for Laser Energetics. A numerical simulation of the alignment procedure is presented. PMID:18806858

  17. Littrow Angle Method to Remove Alignment Errors in Grating Pulse Compressors

    SciTech Connect

    Guardalben, M.J.

    2008-09-16

    An alignment method for pulse-compression gratings that obviates the need to place the gratings at normal incidence to remove grating-tip error is proposed. Grating-tip and groove-orientation errors are removed using two alignment wavelengths in a manner analogous to a laser-beam pointing and centering procedure entirely at the respective Littrow angles for the two wavelengths. By choosing wavelengths with Littrow angles close to the use angle of the grating, the residual tip and groove-orientation errors that may be introduced when the grating mount is tilted to its use angle are reduced. This method has greatly facilitated the alignment of the OMEGA Extended Performance (EP) large-aperture pulse compressors, thereby reducing residual pulse-front tilt caused by nonparallel gratings. OMEGA EP is a highenergy, petawatt-class laser at the University of Rochester’s Laboratory for Laser Energetics. A numerical simulation of the alignment procedure is presented.

  18. Littrow angle method to remove alignment errors in grating pulse compressors

    SciTech Connect

    Guardalben, M. J

    2008-09-20

    An alignment method for pulse-compression gratings that obviates the need to place the gratings at normal incidence to remove grating-tip error is proposed. Grating-tip and groove-orientation errors are removed using two alignment wavelengths in a manner analogous to a laser-beam pointing and centering procedure entirely at the respective Littrow angles for the two wavelengths. By choosing wavelengths with Littrow angles close to the use angle of the grating, the residual tip and groove-orientation errors that may be introduced when the grating mount is tilted to its use angle are reduced. This method has greatly facilitated the alignment of the OMEGA Extended Performance (EP) large-aperture pulse compressors, thereby reducing residual pulse-front tilt caused by nonparallel gratings. OMEGA EP is a high-energy, petawatt-class laser at the University of Rochester's Laboratory for Laser Energetics. A numerical simulation of the alignment procedure is presented.

  19. Apparatus and method for recharging a string a avalanche transistors within a pulse generator

    DOEpatents

    Fulkerson, E. Stephen

    2000-01-01

    An apparatus and method for recharging a string of avalanche transistors within a pulse generator is disclosed. A plurality of amplification stages are connected in series. Each stage includes an avalanche transistor and a capacitor. A trigger signal, causes the apparatus to generate a very high voltage pulse of a very brief duration which discharges the capacitors. Charge resistors inject current into the string of avalanche transistors at various points, recharging the capacitors. The method of the present invention includes the steps of supplying current to charge resistors from a power supply; using the charge resistors to charge capacitors connected to a set of serially connected avalanche transistors; triggering the avalanche transistors; generating a high-voltage pulse from the charge stored in the capacitors; and recharging the capacitors through the charge resistors.

  20. Radiolysis and Ageing of C2-BTP in Cinnamaldehyde/Hexanol Mixtures

    SciTech Connect

    Fermvik, Anna; Ekberg, Christian; Retegan, Teodora; Skarnemark, Gunnar

    2007-07-01

    The separation of actinides from lanthanides is an important step in the alternative methods for nuclear waste treatment currently under development. Polycyclic molecules containing nitrogen are synthesised and used for solvent extraction. A potential problem in the separation process is the degradation of the molecule due to irradiation or ageing. An addition of nitrobenzene has proved to have an inhibitory effect on degradation when added to a system containing C2-BTP in hexanol before irradiation. In this study, 2,6-di(5,6-diethyl-1,2,4-triazine-3-yl)pyridine (C2-BTP) was dissolved in different mixtures of cinnamaldehyde and hexanol and the effects on extraction after ageing and irradiation were investigated. Similar to nitrobenzene, cinnamaldehyde contains an aromatic ring which generally has a relatively high resistance towards radiolysis. Both C2-BTP in cinnamaldehyde and C2-BTP in hexanol seem to degrade with time. The system with C2-BTP in pure hexanol is relatively stable up to 17 days but then starts slowly to degrade. The solution with pure cinnamaldehyde as diluent started to degrade after only {approx}20 hours. The opposite is true for degradation caused by radiolysis; hexanol systems are more sensitive to radiolysis than cinnamaldehyde systems. Most of the radiolytic degradation took place during the first days of irradiation, up to a dose of 4 kGy. (authors)

  1. Investigation of an innovative method for DC flow suppression of double-inlet pulse tube coolers

    NASA Astrophysics Data System (ADS)

    Hu, J. Y.; Luo, E. C.; Wu, Z. H.; Dai, W.; Zhu, S. L.

    2007-05-01

    The use of double-inlet mode in the pulse tube cooler opens up a possibility of DC flow circulating around the regenerator and the pulse tube. The DC flow sometimes deteriorates the performance of the cryocooler because such a steady flow adds an unwanted thermal load to the cold heat exchanger. It seems that this problem is still not well solved although a lot of effort has been made. Here we introduce a membrane-barrier method for DC flow suppression in double-inlet pulse tube coolers. An elastic membrane is installed between the pulse tube cooler inlet and the double-inlet valve to break the closed-loop flow path of DC flow. The membrane is acoustically transparent, but would block the DC flow completely. Thus the DC flow is thoroughly suppressed and the merit of double-inlet mode is remained. With this method, a temperature reduction of tens of Kelvin was obtained in our single-stage pulse tube cooler and the lowest temperature reached 29.8 K.

  2. Pulsed holographic microscopy as a measurement method of dynamic fracture toughness for fast propagating cracks

    NASA Astrophysics Data System (ADS)

    Suzuki, Shinichi; Homma, Hiroomi; Kusaka, Riichiro

    A METHOD OF pulsed holographic microscopy is applied to take instantaneous microscopic photographs of the neighborhoods of crack tips propagating through PMMA or through AISI 4340 steel specimens at a speed of several hundred meters per second. The cracks are in the opening mode. A fast propagating crack is recorded as a hologram at an instant during its propagation. A microscopic photograph of the crack is taken with a conventional microscope to magnify the reconstructed image from the hologram. From the microscopic photograph, crack opening displacement (COD) is measured along the crack in the vicinity of the crack tip. The COD is of the order often to one hundred microns, and in proportion to the square root of the distance from the crack tip. The dynamic fracture toughness KID is obtained using the formula for COD in the singular stress field of a fast propagating crack. Simultaneous KID measurement both through pulsed holographic microscopy and through the caustic method is furthermore carried out with PMMA specimens. The values of KID obtained through pulsed holographic microscopy are in agreement with those through the caustic method. Microcracks accompanied by a main crack are also photographed with the method of pulsed holographic microscopy.

  3. Laser pulse transient method for measuring the normal spectral emissivity of samples with arbitrary surface quality

    NASA Astrophysics Data System (ADS)

    Jeromen, A.; Grabec, I.; Govekar, E.

    2008-09-01

    A laser pulse transient method for measuring normal spectral emissivity is described. In this method, a laser pulse ( λ=1064 nm) irradiates the top surface of a flat specimen. A two-dimensional temperature response of the bottom surface is measured with a calibrated thermographic camera. By solving an axisymmetric boundary value heat conduction problem, the normal spectral emissivity at 1064 nm is determined by using an iterative nonlinear least-squares estimation procedure. The method can be applied to arbitrary sample surface quality. The method is tested on a nickel specimen and used to determine the normal spectral emissivity of AISI 304 stainless steel. The expanded combined uncertainty of the method has been estimated to be 18%.

  4. Method and circuit for controlling the evolution time interval of a laser output pulse

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P. (Inventor)

    1992-01-01

    The invention is a method and circuit for controlling the evolution time interval of a laser output pulse used for making precise spectral measurements. It comprises the means for pumping a laser medium in a resonator that includes a Q-switch and polarizer that act in combination to control the loss in the resonator. A photodiode senses the resulting fluorescence which is applied to a two level Q-switch and polarizer from high to intermediate to substantially zero loss states to control the evolution time interval of the resulting laser output pulse.

  5. Practical method and device for enhancing pulse contrast ratio for lasers and electron accelerators

    DOEpatents

    Zhang, Shukui; Wilson, Guy

    2014-09-23

    An apparatus and method for enhancing pulse contrast ratios for drive lasers and electron accelerators. The invention comprises a mechanical dual-shutter system wherein the shutters are placed sequentially in series in a laser beam path. Each shutter of the dual shutter system has an individually operated trigger for opening and closing the shutter. As the triggers are operated individually, the delay between opening and closing first shutter and opening and closing the second shutter is variable providing for variable differential time windows and enhancement of pulse contrast ratio.

  6. Analysis of Crystallographic Structure of a Japanese Sword by the Pulsed Neutron Transmission Method

    NASA Astrophysics Data System (ADS)

    Kino, K.; Ayukawa, N.; Kiyanagi, Y.; Uchida, T.; Uno, S.; Grazzi, F.; Scherillo, A.

    We measured two-dimensional transmission spectra of pulsed neutron beams for a Japanese sword sample. Atom density, crystalline size, and preferred orientation of crystals were obtained using the RITS code. The position dependence of the atomic density is consistent with the shape of the sample. The crystalline size is very small and shows position dependence, which is understood by the unique structure of Japanese swords. The preferred orientation has strong position dependence. Our study shows the usefulness of the pulsed neutron transmission method for cultural metal artifacts.

  7. Method and apparatus for generating high power laser pulses in the two to six micron wavelength range

    DOEpatents

    MacPherson, David C.; Nelson, Loren D.; O'Brien, Martin J.

    1996-01-01

    Apparatus performs a method of generating one or more output laser pulses in a range of 2 to 6 microns. When a plurality of the output laser pulses are generated, a first output pulse has any selected wavelength within the range and a second output pulse is temporally closely spaced relative to the first output pulse and has a chosen wavelength differing from the selected wavelength. An oscillator laser cavity is provided with a tunable oscillator rod capable of generating initial laser pulses within a range of from 750 to 1000 nm, and a tuning element is coupled to the rod. A flashlamp is operable to pump the rod. For two pulse operation, the flashlamp has a given duration. A Q-switch provides the initial laser pulses upon operation of the tuning element and the flashlamp. A Raman device coupled to the rod shifts the wavelength of such initial laser pulse into the range of from 2 to 6 microns to form the output laser pulse having a wavelength within the range. For multiple pulses, a controller causes the Q-switch to provide first and second ones of the initial laser pulses, spaced by a time interval less than the given duration. Also, a selector coupled to the tuning element is operable within such duration to successively select the wavelength of the first output pulse and the chosen wavelength of the second initial pulse. The Raman device is responsive to each of the initial light pulses to generate radiation at first and second Stokes wavelengths, each of said the output laser pulses being radiation at the second Stokes wavelength.

  8. Method and apparatus for generating high power laser pulses in the two to six micron wavelength range

    DOEpatents

    MacPherson, D.C.; Nelson, L.D.; O`Brien, M.J.

    1996-12-10

    Apparatus performs a method of generating one or more output laser pulses in a range of 2 to 6 microns. When a plurality of the output laser pulses are generated, a first output pulse has any selected wavelength within the range and a second output pulse is temporally closely spaced relative to the first output pulse and has a chosen wavelength differing from the selected wavelength. An oscillator laser cavity is provided with a tunable oscillator rod capable of generating initial laser pulses within a range of from 750 to 1000 nm, and a tuning element is coupled to the rod. A flashlamp is operable to pump the rod. For two pulse operation, the flashlamp has a given duration. A Q-switch provides the initial laser pulses upon operation of the tuning element and the flashlamp. A Raman device coupled to the rod shifts the wavelength of such initial laser pulse into the range of from 2 to 6 microns to form the output laser pulse having a wavelength within the range. For multiple pulses, a controller causes the Q-switch to provide first and second ones of the initial laser pulses, spaced by a time interval less than the given duration. Also, a selector coupled to the tuning element is operable within such duration to successively select the wavelength of the first output pulse and the chosen wavelength of the second initial pulse. The Raman device is responsive to each of the initial light pulses to generate radiation at first and second Stokes wavelengths, each of said the output laser pulses being radiation at the second Stokes wavelength. 30 figs.

  9. Sample preparation method for glass welding by ultrashort laser pulses yields higher seam strength

    SciTech Connect

    Cvecek, K.; Miyamoto, I.; Strauss, J.; Wolf, M.; Frick, T.; Schmidt, M.

    2011-05-01

    Glass welding by ultrashort laser pulses allows joining without the need of an absorber or a preheating and postheating process. However, cracks generated during the welding process substantially impair the joining strength of the welding seams. In this paper a sample preparation method is described that prevents the formation of cracks. The measured joining strength of samples prepared by this method is substantially higher than previously reported values.

  10. The radiolysis and radioracemization of amino acids on silica surfaces

    NASA Technical Reports Server (NTRS)

    Bonner, W. A.; Lemmon, R. M.

    1981-01-01

    Results are presented of experiments on the radioracemization of amino acids in the presence of silica surfaces such as may have been found on the prebiotic earth. L-leucine and a DL-leucine mixture deposited on samples of 1-quartz and an amorphous silica preparation (Syloid 63) was subjected to Co-60 gamma-ray irradiation, then analyzed by gas chromatography to determine the radiolysis and racemization rates. The quartz surface is found to have a marginal efficacy in enhancing radiolysis when compared with a crystalline L-leucine control, although enhancing radioracemization symmetrically by a factor of two. Both the radiolysis and radioracemization of L-leucine and DL-leucine on a Syloid-63 silica surface are observed to increase with increasing radiation dose, and to be substantially greater than in the crystalline controls. Additional experiments with the nonprotein amino acid isovaline deposited on Syloid 63 confirm the greater radiolysis susceptibility of amino acids deposited on silica with respect to the crystalline state, although racemization is not observed. The observations suggest that the presence of a silica surface would have a deleterious effect on any mechanism for the origin of molecular chirality relying on stereoselective beta-radiolysis.

  11. Characterization of the 4-oxo-2,2,6,6-tetramethylpiperidinooxy dosimeter for in situ radiolysis electron spin resonance studies.

    PubMed

    Madden, K P

    1997-03-01

    The stable free radical 4-oxo-2,2,6,6-tetramethylpiperidinooxy (2,2,6,6-tetramethylpiperidone-N-oxyl, TEMPONE) in nitrous oxide-saturated aqueous formate solution has been shown to be a quantitative dosimeter for in situ radiolysis electron spin resonance (ESR) studies. The bleach of the TEMPONE ESR signal is proportional to the absorbed dose in steady-state radiolysis/field-modulation and in pulse radiolysis/time-resolved studies. The G value for consumption of TEMPONE in nitrogen-deoxygenated solution is 5.3 (molecules per 100 eV), while the value in nitrous oxide-saturated solution is 6.0. Measurement of the radiolytically produced yield of carbon dioxide shows that the product of reaction of carbon dioxide radical anion with TEMPONE gives the corresponding hydroxylamine. The stability of the integrated intensity of the TEMPONE ESR bleach has been evaluated in the presence and absence of oxygen and found to be stable for hours. The ESR linewidth of TEMPONE solutions irradiated under anoxic conditions was constant in the postirradiation period. However, when oxygen was added postirradiation, the oxygen-broadened ESR linewidth decreased slowly toward the width observed in anoxic media, indicating consumption of dioxygen by, with concomitant production of, diamagnetic species in solution. PMID:9052680

  12. Measurement of dynamic magnetization induced by a pulsed field: Proposal for a new rock magnetism method

    NASA Astrophysics Data System (ADS)

    Kodama, Kazuto

    2015-02-01

    This study proposes a new method for measuring transient magnetization of natural samples induced by a pulsed field with duration of 11 ms using a pulse magnetizer. An experimental system was constructed, consisting of a pair of differential sensing coils connected with a high-speed digital oscilloscope for data acquisition. The data were transferred to a computer to obtain an initial magnetization curve and a descending branch of a hysteresis loop in a rapidly changing positive field. This system was tested with synthetic samples (permalloy ribbon, aluminum plate, and nickel powder) as well as two volcanic rock samples. Results from the synthetic samples showed considerable differences from those measured by a quasi-static method using a vibrating sample magnetometer (VSM). These differences were principally due to the time-dependent magnetic properties or to electromagnetic effects, such as magnetic viscosity, eddy current loss, or magnetic relaxation. Results from the natural samples showed that the transient magnetization-field curves were largely comparable to the corresponding portions of the hysteresis loops. However, the relative magnetization (scaled to the saturation magnetization) at the end of a pulse was greater than that measured by a VSM. This discrepancy, together with the occurrence of rapid exponential decay after a pulse, indicates magnetic relaxations that could be interpreted in terms of domain wall displacement. These results suggest that with further developments, the proposed technique can become a useful tool for characterizing magnetic particles contained in a variety of natural materials.

  13. Time-resolved resonance Raman spectroscopy of radiation-chemical processes. [Pulsed irradiation

    SciTech Connect

    Tripathi, G.N.R.

    1983-01-01

    A tunable pulsed laser Raman spectrometer for time resolved Raman studies of radiation-chemical processes is described. This apparatus utilizes the state of art optical multichannel detection and analysis techniques for data acquisition and electron pulse radiolysis for initiating the reactions. By using this technique the resonance Raman spectra of intermediates with absorption spectra in the 248-900 nm region, and mean lifetimes > 30 ns can be examined. This apparatus can be used to time resolve the vibrational spectral overlap between transients absorbing in the same region, and to follow their decay kinetics by monitoring the well resolved Raman peaks. For kinetic measurements at millisecond time scale, the Raman technique is preferable over optical absorption method where low frequency noise is quite bothersome. A time resolved Raman study of the pulse radiolytic oxidation of aqueous tetrafluorohydroquinone and p-methoxyphenol is briefly discussed. 15 references, 5 figures.

  14. Various methods of optimizing control pulses for quantum systems with decoherence

    NASA Astrophysics Data System (ADS)

    Pawela, Łukasz; Sadowski, Przemysław

    2016-05-01

    We design control setting that allows the implementation of an approximation of an unitary operation of a quantum system under decoherence using various quantum system layouts and numerical algorithms. We focus our attention on the possibility of adding ancillary qubits which help to achieve a desired quantum map on the initial system. Furthermore, we use three methods of optimizing the control pulses: genetic optimization, approximate evolution method and approximate gradient method. To model the noise in the system we use the Lindblad equation. We obtain results showing that applying the control pulses to the ancilla allows one to successfully implement unitary operation on a target system in the presence of noise, which is not possible which control field applied to the system qubits.

  15. Evaluation of cardiac output by 5 arterial pulse contour techniques using trend interchangeability method.

    PubMed

    Fischer, Marc-Olivier; Diouf, Momar; Wilde, Robert B P de; Dupont, Hervé; Hanouz, Jean-Luc; Lorne, Emmanuel

    2016-06-01

    Cardiac output measurement with pulse contour analysis is a continuous, mini-invasive, operator-independent, widely used, and cost-effective technique, which could be helpful to assess changes in cardiac output. The 4-quadrant plot and the polar plot have been described to compare the changes between 2 measurements performed under different conditions, and the direction of change by using different methods of measurements. However, the 4-quadrant plot and the polar plot present a number of limitations, with a risk of misinterpretation in routine clinical practice. We describe a new trend interchangeability method designed to objectively define the interchangeability of each change of a variable. Using the repeatability of the reference method, we classified each change as either uninterpretable or interpretable and then as either noninterchangeable, in the gray zone or interchangeable. An interchangeability rate can then be calculated by the number of interchangeable changes divided by the total number of interpretable changes. In this observational study, we used this objective method to assess cardiac output changes with 5 arterial pulse contour techniques (Wesseling's method, LiDCO, PiCCO, Hemac method, and Modelflow) in comparison with bolus thermodilution technique as reference method in 24 cardiac surgery patients. A total of 172 cardiac output variations were available from the 199 data points: 88 (51%) were uninterpretable, according to the first step of the method. The second step of the method, based on the 84 (49%) interpretable variations, showed that only 18 (21%) to 30 (36%) variations were interchangeable regardless of the technique used. None of pulse contour cardiac output technique could be interchangeable with bolus thermodilution to assess changes in cardiac output using the trend interchangeability method in cardiac surgery patients. Future studies may consider using this method to assess interchangeability of changes between different methods

  16. Novel plasma-based frequency upshift methods for short pulse lasers

    SciTech Connect

    Wilks, S.C. ); Dawson, J.M.; Mori, W.B. . Dept. of Physics)

    1990-06-04

    We discuss various novel methods of frequency upshifting short ({le} 1 picosecond) pulses of laser light. All of these methods make use of either the sudden creation of a plasma or relativistic plasma waves. The first method discussed is known as photon acceleration. This method makes use of the fact that a laser pulse moving in a plasma can be thought of as a packet of photons, each possessing an effective mass of m{sub {gamma}} = {h bar}{omega}{sub pe}/c{sup 2} and moving with the group velocity of the laser pulse. These photons experience a force acting on them when in the presence of a gradient in the plasma density. By using a relativistic plasma wave (i.e., a moving density gradient) traveling with the photons, the energy of the photons (thus the frequency) can be continuously increased. We then discuss the sudden creation of a plasma in a region where there exists an electromagnetic wave. This results in a frequency shift of the wave. A similar method is the creation of an ionization front moving near the speed of light, whereby the interaction of this plasma front with an EM wave also results in a frequency upshift of the original wave. 21 refs.

  17. Summary Report on Gamma Radiolysis of TBP/n-dodecane in the Presence of Nitric Acid Using the Radiolysis/Hydrolysis Test Loop

    SciTech Connect

    Dean R. Peterman; Bruce J. Mincher; Catherine L. Riddle; Richard D. Tillotson

    2010-08-01

    processes containing TBP that are being developed to support advanced aqueous separations processes. Initial experimental results are consistent with existing literature reports regarding TBP/n-dodecane radiolysis. Additionally, the gamma dose rate has been characterized within the test loop and analytical methods have been developed for the characterization and quantification of radiolytic degradation products.

  18. Modeling of water radiolysis at spallation neutron sources

    SciTech Connect

    Daemen, L.L.; Kanner, G.S.; Lillard, R.S.; Butt, D.P.; Brun, T.O.; Sommer, W.F.

    1998-12-01

    In spallation neutron sources neutrons are produced when a beam of high-energy particles (e.g., 1 GeV protons) collides with a (water-cooled) heavy metal target such as tungsten. The resulting spallation reactions produce a complex radiation environment (which differs from typical conditions at fission and fusion reactors) leading to the radiolysis of water molecules. Most water radiolysis products are short-lived but extremely reactive. When formed in the vicinity of the target surface they can react with metal atoms, thereby contributing to target corrosion. The authors will describe the results of calculations and experiments performed at Los Alamos to determine the impact on target corrosion of water radiolysis in the spallation radiation environment. The computational methodology relies on the use of the Los Alamos radiation transport code, LAHET, to determine the radiation environment, and the AEA code, FACSIMILE, to model reaction-diffusion processes.

  19. Mechanical property measurements of nanofilm by microbump method induced by laser pulse

    NASA Astrophysics Data System (ADS)

    Dun, Aihuan; Wei, Jingsong

    2015-12-01

    A laser pulse-induced microbump method that aims to measure the mechanical properties of nanofilms is proposed. The sample structure is designed as `substrate/AgO x (active layer)/ZnS-SiO2 (nanofilm)' and the laser pulse is applied to heat the active layer and to create a microbump. The deflections of the microbumps are measured precisely by atomic force microscopy by taking AgO x and ZnS-SiO2 as the active layer and nanofilm, respectively, and by controlling the pulse laser parameters. By transforming the laser power-deflection curve to a pressure-deflection curve, the calculation equations of mechanical properties were strictly derived according to the action principle of a Gaussian intensity profile pulse laser with material and traditional bulge testing equations. The mechanical properties of a ZnS-SiO2 film with only 10-nm thickness were calculated according to the derived equations. The results of the ZnS-SiO2 film are as follows: residual stress is 0.129 MPa, Young's modulus is 0.441 MPa, and Poisson's ratio is 0.217.

  20. Compressive strength evaluation of structural lightweight concrete by non-destructive ultrasonic pulse velocity method.

    PubMed

    Bogas, J Alexandre; Gomes, M Glória; Gomes, Augusto

    2013-07-01

    In this paper the compressive strength of a wide range of structural lightweight aggregate concrete mixes is evaluated by the non-destructive ultrasonic pulse velocity method. This study involves about 84 different compositions tested between 3 and 180 days for compressive strengths ranging from about 30 to 80 MPa. The influence of several factors on the relation between the ultrasonic pulse velocity and compressive strength is examined. These factors include the cement type and content, amount of water, type of admixture, initial wetting conditions, type and volume of aggregate and the partial replacement of normal weight coarse and fine aggregates by lightweight aggregates. It is found that lightweight and normal weight concretes are affected differently by mix design parameters. In addition, the prediction of the concrete's compressive strength by means of the non-destructive ultrasonic pulse velocity test is studied. Based on the dependence of the ultrasonic pulse velocity on the density and elasticity of concrete, a simplified expression is proposed to estimate the compressive strength, regardless the type of concrete and its composition. More than 200 results for different types of aggregates and concrete compositions were analyzed and high correlation coefficients were obtained. PMID:23351273

  1. A time-resolved Langmuir double-probe method for the investigation of pulsed magnetron discharges

    SciTech Connect

    Welzel, Th.; Dunger, Th.; Kupfer, H.; Richter, F.

    2004-12-15

    Langmuir probes are important means for the characterization of plasma discharges. For measurements in plasmas used for the deposition of thin films, the Langmuir double probe is especially suited. With the increasing popularity of pulsed deposition discharges, there is also an increasing need for time-resolved characterization methods. For Langmuir probes, several single-probe approaches to time-resolved measurements are reported but very few for the double probe. We present a time-resolved Langmuir double-probe technique, which is applied to a pulsed magnetron discharge at several 100 kHz used for MgO deposition. The investigations show that a proper treatment of the current measurement is necessary to obtain reliable results. In doing so, a characteristic time dependence of the charge-carrier density during the ''pulse on'' time containing maximum values of almost 2{center_dot}10{sup 11} cm{sup -3} was found. This characteristic time dependence varies with the pulse frequency and the duty cycle. A similar time dependence of the electron temperature is only observed when the probe is placed near the magnesium target.

  2. Pulsed-wave perturbation in a borehole during the pneumohydraulic method of coal extraction

    SciTech Connect

    Zorin, A.N.; Didenko, A.T.; Kolesnikov, V.G.; Pirich, Y.T.

    1985-05-01

    One recent trend in coal extraction includes methods based on the artificial creation of a blowout-hazard situation, and the use of the phenomenon of blowout for the extraction of coal through boreholes in the form of coal pulp or friable material. The blowout-hazard situation and blowout are produced by the injection into the borehole of liquid and gas under high pressure, with subsequent sharp pressure drop, leading to the generation of demolition waves and the removal of the coal through the borehole. To apply these methods it is necessary to carry out an assessment of the conditions and parameters of the pulsed action on the seam through the borehole, leading to demolition of the coal. The authors study here the conditions of propagation of the pulse generated by the pressure drop, along the gas-liquid column, in the borehole.

  3. Cepstral method for the measurement of ultrasonic pulse transmission time variations

    NASA Astrophysics Data System (ADS)

    Gericke, Otto R.

    1989-04-01

    A precise method for determining relative changes or small differences in ultra-sonic pulse transmission times has been developed. The method uses multiple-echo signals obtained by injecting a pulsed, plane ultrasonic wave of the compressional mode into a sample with free, parallel surfaces. The ultrasonic transducer employed for this purpose acts as both transmitter and receiver. The received ultrasonic signals are subjected to two consecutive Fourier transformations to produce a cepstrum. The cepstral function derived from the multiple-echo signal exhibits characteristic maxima whose positions on the frequency abscissa, after calibration in units of time, represent multiples of the ultrasonic transmission time. Since minute variations of this time can be determined from a shift in the position of a cepstral maximum, the detection of very small changes or differences in sample thickness or ultrasonic propagation velocity becomes feasible.

  4. Synthesis of Nano-Crystalline CO3O4 Particles by Hydrothermal Method Under Pulsed Magnetic Field

    NASA Astrophysics Data System (ADS)

    Deng, Xiaolong; Li, Ying; Zhu, Mingyuan; Jin, Hongming; Wang, Zhun; Zhu, Zhenzhen; Liu, Huakun

    Nanocrystalline CO3O4 particles were successfully synthesized by hydrothermal method under pulsed magnetic field. The effect of magnetic field and aging time on the morphology and microstructure were examined. Different morphologies were observed from SEM images for the samples fabricated with or without pulsed magnetic field. The pulsed magnetic field made CO3O4 sphere compact and more smooth surface. The hollow sphere morphology and refined grain of CO3O4 were formed after aging process.

  5. Magnetic field error measurement of the CEBAF (NIST) wiggler using the pulsed wire method

    SciTech Connect

    Wallace, Stephen; Colson, William; Neil, George; Harwood, Leigh

    1993-07-01

    The National Institute for Science and Technology (NIST) wiggler has been loaded to the Continuous Electron Beam Accelerator Facility (CEBAF). The pulsed wire method [R.W. Warren, Nucl. Instr. and Meth. A272 (1988) 267] has been used to measure the field errors of the entrance wiggler half, and the net path deflection was calculated to be Δx ≈ 5.2 m.

  6. Method and apparatus for improving the quality and efficiency of ultrashort-pulse laser machining

    DOEpatents

    Stuart, Brent C.; Nguyen, Hoang T.; Perry, Michael D.

    2001-01-01

    A method and apparatus for improving the quality and efficiency of machining of materials with laser pulse durations shorter than 100 picoseconds by orienting and maintaining the polarization of the laser light such that the electric field vector is perpendicular relative to the edges of the material being processed. Its use is any machining operation requiring remote delivery and/or high precision with minimal collateral dames.

  7. TRUEX Radiolysis Testing Using the INL Radiolysis Test Loop: FY-2012 Status Report

    SciTech Connect

    Dean R. Peterman; Lonnie G. Olson; Richard D. Tillotson; Rocklan G. McDowell; Jack D. Law

    2012-09-01

    The INL radiolysis test loop has been used to evaluate the affect of radiolytic degradation upon the efficacy of the strip section of the TRUEX flowsheet for the recovery of trivalent actinides and lanthanides from acidic solution. The nominal composition of the TRUEX solvent used in this study is 0.2 M CMPO and 1.4 M TBP dissolved in n-dodecane and the nominal composition of the TRUEX strip solution is 1.5 M lactic acid and 0.050 M diethylenetriaminepentaacetic acid. Gamma irradiation of a mixture of TRUEX process solvent and stripping solution in the test loop does not adversely impact flowsheet performance as measured by stripping americium ratios. The observed increase in americium stripping distribution ratios with increasing absorbed dose indicates the radiolytic production of organic soluble degradation compounds.

  8. Summary of TRUEX Radiolysis Testing Using the INL Radiolysis Test Loop

    SciTech Connect

    Dean R. Peterman; Lonnie G. Olson; Rocklan G. McDowell; Gracy Elias; Jack D. Law

    2012-03-01

    The INL radiolysis and hydrolysis test loop has been used to evaluate the effects of hydrolytic and radiolytic degradation upon the efficacy of the TRUEX flowsheet for the recovery of trivalent actinides and lanthanides from acidic solution. Repeated irradiation and subsequent re-conditioning cycles did result in a significant decrease in the concentration of the TBP and CMPO extractants in the TRUEX solvent and a corresponding decrease in americium and europium extraction distributions. However, the build-up of solvent degradation products upon {gamma}-irradiation, had little impact upon the efficiency of the stripping section of the TRUEX flowsheet. Operation of the TRUEX flowsheet would require careful monitoring to ensure extraction distributions are maintained at acceptable levels.

  9. Method of high precision interval measurement in pulse laser ranging system

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Lv, Xin-yuan; Mao, Jin-jin; Liu, Wei; Yang, Dong

    2013-09-01

    Laser ranging is suitable for laser system, for it has the advantage of high measuring precision, fast measuring speed,no cooperative targets and strong resistance to electromagnetic interference,the measuremen of laser ranging is the key paremeters affecting the performance of the whole system.The precision of the pulsed laser ranging system was decided by the precision of the time interval measurement, the principle structure of laser ranging system was introduced, and a method of high precision time interval measurement in pulse laser ranging system was established in this paper.Based on the analysis of the factors which affected the precision of range measure,the pulse rising edges discriminator was adopted to produce timing mark for the start-stop time discrimination,and the TDC-GP2 high precision interval measurement system based on TMS320F2812 DSP was designed to improve the measurement precision.Experimental results indicate that the time interval measurement method in this paper can obtain higher range accuracy. Compared with the traditional time interval measurement system,the method simplifies the system design and reduce the influence of bad weather conditions,furthermore,it satisfies the requirements of low costs and miniaturization.

  10. Pulse wave detection method based on the bio-impedance of the wrist.

    PubMed

    He, Jianman; Wang, Mengjun; Li, Xiaoxia; Li, Gang; Lin, Ling

    2016-05-01

    The real-time monitoring of pulse rate can evaluate the heart health to some extent, and the measurement of bio-impedance has the potential in wearable health monitoring system. In this paper, an effective method, which contains self-balancing bridge, flexible electrode, and high-speed digital lock-in algorithm (DLIA) with over-sampling, was designed to detect the impedance pulse wave at the wrist. By applying the self-balancing bridge, the basic impedance can be compensated as much as possible, and the low amplitude of impedance variation related to heart pulse can be obtained more easily. And the flexible conductive rubber electrode used in our experiment is human-friendly. Besides, the over-sampling method and high-speed DLIA are used to enhance the effective resolution of the existing data sampled by analog to digital converter. With the high-speed data process and simple circuit above, this proposed method has the potential in wrist-band wearable systems and it can satisfy quests of small volume and low power consumption. PMID:27250460

  11. Pulse wave detection method based on the bio-impedance of the wrist

    NASA Astrophysics Data System (ADS)

    He, Jianman; Wang, Mengjun; Li, Xiaoxia; Li, Gang; Lin, Ling

    2016-05-01

    The real-time monitoring of pulse rate can evaluate the heart health to some extent, and the measurement of bio-impedance has the potential in wearable health monitoring system. In this paper, an effective method, which contains self-balancing bridge, flexible electrode, and high-speed digital lock-in algorithm (DLIA) with over-sampling, was designed to detect the impedance pulse wave at the wrist. By applying the self-balancing bridge, the basic impedance can be compensated as much as possible, and the low amplitude of impedance variation related to heart pulse can be obtained more easily. And the flexible conductive rubber electrode used in our experiment is human-friendly. Besides, the over-sampling method and high-speed DLIA are used to enhance the effective resolution of the existing data sampled by analog to digital converter. With the high-speed data process and simple circuit above, this proposed method has the potential in wrist-band wearable systems and it can satisfy quests of small volume and low power consumption.

  12. Valine radiolysis by MeV ions

    NASA Astrophysics Data System (ADS)

    Da Silveira, Enio

    2016-07-01

    Valine, (CH3)2 CHCH (NH2) COOH, is a protein amino acid that has been identified in extraterrestrial environments and in the Murchison meteorite [1]. The knowledge of half-lives of small organic molecules under ionizing radiation is important for the setup of models describing the spread out of prebiotics across the Solar System or the Galaxy. We have investigated typical effects of MeV cosmic ray ions on prebiotic molecules in laboratory by impinging ions produced by the PUC-Rio Van de Graaff accelerator. Pure valine films, deposited by evaporation on KBr substrates, were irradiated by H ^{+}, He ^{+} and N ^{+} ion beams, from 0.5 to 1.5 MeV and up to a fluence of 10 ^{15} projectiles/cm ^{2}. The sample temperature was varied from 10 K to 300 K. The irradiation was interrupted several times for Mid-FTIR analysis of the sample. The main findings are: 1- The column density of the valine decreases exponentially with fluence. 2- In some cases, a second exponential appears in the beginning of irradiation; this feature has been attributed to sample compaction by the ion beam [2]. 3- Destruction cross sections of valine are in the 10 ^{-15} cm ^{2} range, while compaction cross sections are in the 10 ^{-14} cm ^{2} range. 4- Destruction cross section increases with the stopping power of the beam and also with the sample temperature. 5- Surprisingly, during the radiolysis of valine, just CO _{2} is seen by as a daughter molecule formed in the bulk. 6- After long beam fluence, also a CO peak appears in the infrared spectrum; this species is however interpreted as a fragment of the formed CO2 molecules. 7- Considering the flux ratio between laboratory experiments and actual galactic cosmic rays, half-life of valine is predicted for ISM conditions [3]. This work on pure valine is the first measurement of a series. New experiments are planned for determining cross sections of valine dissolved in H _{2}O or CO _{2}, inspired by the study performed for glycine [4]. [1] P

  13. The influence of dithiothreitol on DNA radiolysis in frozen aqueous solution:. an EPR study

    NASA Astrophysics Data System (ADS)

    Ambroz, H. B.; Kemp, T. J.; Kornacka, E.; Przybytniak, G.

    2002-05-01

    The effect of a thiol, dithiothreitol (DTT), on DNA radiolysis at cryogenic temperatures was investigated by the EPR method. Dithiothreitol repairs up to 30% of DNA radicals, but an increase in the thiol concentration above 10 mM, even up to 1000 mM, does not further enhance the overall level of the repair process. The transfers of paramagnetic centres from both the guanine radical cation, and the allyl radical of thymine, to thiol were observed, while products generated via the reductive pathway remained unaffected.

  14. Measuring solid percentage of oil sands mature fine tailings using the dual probe heat pulse method.

    PubMed

    Li, Min; Barbour, S Lee; Si, Bing Cheng

    2015-01-01

    The reclamation of mature fine tailings (MFT) is a critical challenge for the oil sands industry in western Canada, and a nonradioactive, automated, and inexpensive method to monitor the MFT solidification is needed. The objective of this paper is to evaluate the feasibility of a dual-probe heat pulse (DPHP) method to measure MFT solid percentage. Dual-probe heat pulse measurements were performed on three MFT samples, each at various solid percentages. A linear relationship ( = 0.9495 + 0.0558) was established between the DPHP-measured solid percentage () and that of oven-dry method (). Six additional MFT samples were collected and measured to validate the DPHP method. The specific heats of the six MFT solids were measured independently using a modulated differential scanning calorimetry method, and the sensitivity of DPHP-measured MFT solid percentage to the specific heat of MFT solids was evaluated. The result shows that the DPHP method can be used to accurately measure MFT solid percentages, and the accuracy can be further improved if the specific heat of the MFT solids is measured independently. PMID:25602345

  15. [Application of three heat pulse technique-based methods to determine the stem sap flow].

    PubMed

    Wang, Sheng; Fan, Jun

    2015-08-01

    It is of critical importance to acquire tree transpiration characters through sap flow methodology to understand tree water physiology, forest ecology and ecosystem water exchange. Tri-probe heat pulse sensors, which are widely utilized in soil thermal parameters and soil evaporation measurement, were applied to implement Salix matsudana sap flow density (Vs) measurements via heat-ratio method (HRM), T-Max method (T-Max) and single-probe heat pulse probe (SHPP) method, and comparative analysis was conducted with additional Grainer's thermal diffusion probes (TDP) measured results. The results showed that, it took about five weeks to reach a stable measurement stage after TPHP installation, Vs measured with three methods in the early stage after installation was 135%-220% higher than Vs in the stable measurement stage, and Vs estimated via HRM, T-Max and SHPP methods were significantly linearly correlated with Vs estimated via TDP method, with R2 of 0.93, 0.73 and 0.91, respectively, and R2 for Vs measured by SHPP and HRM reached 0.94. HRM had relatively higher precision in measuring low rates and reverse sap flow. SHPP method seemed to be very promising to measure sap flow for configuration simplicity and high measuring accuracy, whereas it couldn' t distinguish directions of flow. T-Max method had relatively higher error in sap flow measurement, and it couldn' t measure sap flow below 5 cm3 · cm(-2) · h(-1), thus this method could not be used alone, however it could measure thermal diffusivity for calculating sap flow when other methods were imposed. It was recommended to choose a proper method or a combination of several methods to measure stem sap flow, based on specific research purpose. PMID:26685585

  16. Comparative analysis of pulse shape discrimination methods in a 6Li loaded plastic scintillator

    NASA Astrophysics Data System (ADS)

    Balmer, Matthew J. I.; Gamage, Kelum A. A.; Taylor, Graeme C.

    2015-07-01

    Three algorithms for discriminating between fast neutrons, thermal neutrons and gamma rays in a 6Li loaded plastic scintillator have been compared. Following a literature review of existing pulse shape discrimination techniques, the performance of the charge comparison method, triangular filtering and frequency gradient analysis were investigated in this work. The scintillator was exposed to three different mixed gamma/neutron radiation fields. The figure of merit of neutron/gamma separation was investigated over a broad energy range, as well as for the neutron capture energy region. After optimisation, all three methods were found to perform similarly in terms of neutron/gamma separation.

  17. Methods and optical fibers that decrease pulse degradation resulting from random chromatic dispersion

    DOEpatents

    Chertkov, Michael; Gabitov, Ildar

    2004-03-02

    The present invention provides methods and optical fibers for periodically pinning an actual (random) accumulated chromatic dispersion of an optical fiber to a predicted accumulated dispersion of the fiber through relatively simple modifications of fiber-optic manufacturing methods or retrofitting of existing fibers. If the pinning occurs with sufficient frequency (at a distance less than or are equal to a correlation scale), pulse degradation resulting from random chromatic dispersion is minimized. Alternatively, pinning may occur quasi-periodically, i.e., the pinning distance is distributed between approximately zero and approximately two to three times the correlation scale.

  18. [Visualization of blood flow in abdominal tumors by the ultrasonic pulsed Doppler method].

    PubMed

    Ueno, N; Yamanaka, T; Kimura, K

    1989-06-01

    The clinical utility of visualizing the blood flow in the margin and inside of tumors by ultrasonic pulsed Doppler method (UPDM) was evaluated in 54 patients (85 lesions) with various abdominal tumors. It was proved that UPDM was able to evaluate the vascularity of the tumor and the surrounding vascular system. These results indicate that this method may be applied clinically for judging the effects of and the indications for the transcatheter arterial embolization (TAE) therapy. It is also suggested that UPDM may be applied in the differential diagnosis of tumors according to the changes of blood velocity and wave patterns. PMID:2677449

  19. Enhancement of Zirconolite Dissolution Due to Water Radiolysis

    SciTech Connect

    Tribet, Magaly; Moncoffre, Nathalie

    2007-07-01

    Zirconolite is a candidate host material for conditioning minor tri- and tetra-valent actinides arising from enhanced nuclear spent fuel reprocessing and partitioning, in the case of disposal of the nuclear waste. Its chemical durability has been studied here under charged particle-induced radiolysis (He{sup 2+} and proton external beams) to identify the possible effects of water radiolysis on the dissolution rates in pure water and to describe the alteration mechanisms. Two experimental geometries have been used in order to evaluate the influence of the following parameters: solid irradiation, water radiolysis. In the first geometry the beam gets through the sample before stopping at the surface/water interface. In the second one the beam stops before the surface/water interface. Results on the elemental releases due to the enhanced dissolution of the zirconolite surface during charged particle-induced irradiation of water are presented. Under radiolysis, an increase of one order of magnitude is observed in the Ti, Zr and Nd elemental releases. No difference in the total elemental releases can be noticed when the solid is also irradiated. (authors)

  20. Method and apparatus for rapidly growing films on substrates using pulsed supersonic jets

    DOEpatents

    Eres, Diula; Lowndes, Douglas H.

    1992-01-01

    A method and apparatus for the rapid and economical deposition of uniform and high quality films upon a substrate for subsequent use in producing electronic devices, for example. The resultant films are either epitaxial (crystalline) or amorphous depending upon the incidence rate and the temperature and structure of the substrate. The deposition is carried out in a chamber maintained at about 10.sup.-6 Torr. A gaseous source of the material for forming the deposit is injected into the deposition chamber in the form of a pulsed supersonic jet so as to obtain a high incidence rate. The supersonic jet is produced by a pulsed valve between a relatively high presure reservoir, containing the source gaseous molecules, and the deposition chamber; the valve has a small nozzle orifice (e.g., 0.1-1.0 mm diameter). The type of deposit (crystalline amorphous) is then dependent upon the temperature and structure of the substrate. Very high deposition rates are achieved, and the deposit is very smooth and of uniform thickness. Typically the deposition rate is about 100 times that of much more expensive conventional molecular beam methods for deposition, and comparable to certain expensive plasma-assisted CVD methods of the art. The high growth rate of this method results in a reduced contamination of the deposit from other elements in the environment. The method is illustrated by the deposition of epitaxial and amorphour germanium films upon GaAs substrates.

  1. An Investigation of Pulse Transit Time as a Non-Invasive Blood Pressure Measurement Method

    NASA Astrophysics Data System (ADS)

    McCarthy, B. M.; O'Flynn, B.; Mathewson, A.

    2011-08-01

    The objective of this paper is to examine the Pulse Transit Method (PTT) as a non-invasive means to track Blood Pressure over a short period of time. PTT was measured as the time it takes for an ECG R-wave to propagate to the finger, where it is detected by a photoplethysmograph sensor. The PTT method is ideal for continuous 24-hour Blood Pressure Measurement (BPM) since it is both cuff-less and non-invasive and therefore comfortable and unobtrusive for the patient. Other techniques, such as the oscillometric method, have shown to be accurate and reliable but require a cuff for operation, making them unsuitable for long term monitoring. Although a relatively new technique, the PTT method has shown to be able to accurately track blood pressure changes over short periods of time, after which re-calibration is necessary. The purpose of this study is to determine the accuracy of the method.

  2. Method and apparatus for fast laser-pulse detection using gaseous plasmas

    DOEpatents

    McLellan, E.J.; Webb, J.A.

    1981-06-18

    The method and device of the instant invention is a detector of pulsed laser radiation which utilizes the electromotive force generated by the plasma formed when such radiation is focused onto a surface. Measurements are made with a 10.6 ..mu..m CO/sub 2/ laser capable of producing peak intensities of 10/sup 13/ W/cm/sup 2/ when directed through a converging lens. Evacuated detector response to such laser intensity if 1 kV signal peak amplitude and subnanosecond risetimes into a 50 ..cap omega.. load. Detector performance is found to be greatly altered with the introduction of a background gas. For example, with one atmosphere of air, the detector produces prompt signals of the order of 1 V with subnanosecond response for pulse trains lasting 100 ns. With argon, krypton, or zenon at pressures of the order of 10 torr, the detector generates trigger pulses of about 250 V amplitude and 0.2 ns risetimes. Such detectors are quite robust when irradiated with high intensity laser radiation and are useful for qualitative laser beam monitoring.

  3. Method and apparatus for fast laser pulse detection using gaseous plasmas

    DOEpatents

    McLellan, Edward J.; Webb, John A.

    1984-01-01

    The method and device of the instant invention is a detector of pulsed laser radiation which utilizes the electromotive force generated by the plasma formed when such radiation is focused onto a surface (1). Measurements are made with a 10.6 .mu.m CO.sub.2 laser capable of producing peak intensities of 10.sup.13 W/cm.sup.2 when directed through a converging lens (2). Evacuated detector response to such laser intensity is 1 kV signal peak amplitude and subnanosecond risetimes into a 50.OMEGA. load (3). Detector performance is found to be greatly altered with the introduction of a background gas (4). For example, with one atmosphere of air, the detector produces prompt signals of the order of 1 V with subnanosecond response for pulse trains lasting 100 ns. With argon, krypton, or zenon at pressures of the order of 10 torr, the detector generates "trigger pulses" of about 250 V amplitude and 0.2 ns risetimes. Such detectors are quite robust when irradiated with high intensity laser radiation and are useful for qualitative laser beam monitoring.

  4. Investigation of a pulsed current annealing method in reusing MOSFET dosimeters for in vivo IMRT dosimetry

    SciTech Connect

    Luo, Guang-Wen; Qi, Zhen-Yu Deng, Xiao-Wu; Rosenfeld, Anatoly

    2014-05-15

    Purpose: To explore the feasibility of pulsed current annealing in reusing metal oxide semiconductor field-effect transistor (MOSFET) dosimeters forin vivo intensity modulated radiation therapy (IMRT) dosimetry. Methods: Several MOSFETs were irradiated atd{sub max} using a 6 MV x-ray beam with 5 V on the gate and annealed with zero bias at room temperature. The percentage recovery of threshold voltage shift during multiple irradiation-annealing cycles was evaluated. Key dosimetry characteristics of the annealed MOSFET such as the dosimeter's sensitivity, reproducibility, dose linearity, and linearity of response within the dynamic range were investigated. The initial results of using the annealed MOSFETs for IMRT dosimetry practice were also presented. Results: More than 95% of threshold voltage shift can be recovered after 24-pulse current continuous annealing in 16 min. The mean sensitivity degradation was found to be 1.28%, ranging from 1.17% to 1.52%, during multiple annealing procedures. Other important characteristics of the annealed MOSFET remained nearly consistent before and after annealing. Our results showed there was no statistically significant difference between the annealed MOSFETs and their control samples in absolute dose measurements for IMRT QA (p = 0.99). The MOSFET measurements agreed with the ion chamber results on an average of 0.16% ± 0.64%. Conclusions: Pulsed current annealing provides a practical option for reusing MOSFETs to extend their operational lifetime. The current annealing circuit can be integrated into the reader, making the annealing procedure fully automatic.

  5. Method and apparatus for measuring the intensity and phase of an ultrashort light pulse

    DOEpatents

    Kane, Daniel J.; Trebino, Rick P.

    1998-01-01

    The pulse shape I(t) and phase evolution x(t) of ultrashort light pulses are obtained using an instantaneously responding nonlinear optical medium to form a signal pulse. A light pulse, such a laser pulse, is split into a gate pulse and a probe pulse, where the gate pulse is delayed relative to the probe pulse. The gate pulse and the probe pulse are combined within an instantaneously responding optical medium to form a signal pulse functionally related to a temporal slice of the gate pulse corresponding to the time delay of the probe pulse. The signal pulse is then input to a wavelength-selective device to output pulse field information comprising intensity vs. frequency for a first value of the time delay. The time delay is varied over a range of values effective to yield an intensity plot of signal intensity vs. wavelength and delay. In one embodiment, the beams are overlapped at an angle so that a selected range of delay times is within the intersection to produce a simultaneous output over the time delays of interest.

  6. A simplified method for selecting a carbon-fiber electrode in pulse voltammetry.

    PubMed

    Liao, B Y; Lio, H P; Wang, C Y; Young, M S; Ho, M T; Lin, M T

    1993-12-01

    A method for selecting a usable carbon-fiber electrode using the equivalent resistance and capacitance is presented. This method uses an instrument with a PC-based look-up table for measuring the electrical characteristics of a carbon-fiber electrode in pulse voltammetry. Using this instrument, the equivalent resistance and capacitance of the carbon-fiber electrode in saturated sodium chloride solution can be obtained. This instrument includes a decade resistance box, a peak current detection and hold circuit, a half peak comparator and a decay duration counter. A look-up table is established by using RC circuits to emulate the electrochemical reaction of the carbon-fiber electrode in pulse voltammetry. The equivalent resistance is obtained from the decade resistance box according to Kirchhoff's law. Then the equivalent capacitance is determined from the decay duration counter reading and equivalent resistance with the look-up table via a PC interpolation program. After obtaining the equivalent resistance and capacitance of an electrode, the values are compared with the usable thresholds. This method provides an effective quality evaluation index of carbon-fiber electrode for the user in order to reduce electrode-induced experimental failure. The method is also available for other kinds of carbon-fiber electrodes as long as their look-up table and desired thresholds are established. PMID:8152240

  7. AFM and pulsed laser ablation methods for Cultural Heritage: application to archeometric analysis of stone artifacts

    NASA Astrophysics Data System (ADS)

    Barberio, M.; Veltri, S.; Stranges, F.; Bonanno, A.; Xu, F.; Antici, P.

    2015-09-01

    In this paper, we introduce the use of the atomic force microscope (AFM) and of the pulsed laser ablation as methods for morphological diagnostic with nanoscale precision of archeological artifacts and corrosive patina removal from stone artifacts. We test our methodology on stone artifacts extracted from the Church of Sotterra (located in Calabria, South Italy). The AFM microscopy was compared with different petrographic, chemical, optical and morphological analysis methods for identifying the textural characteristics, evaluating the state of preservation and formulating some hypotheses about the provenance and composition of the impurity patina located on the artifact surfaces. We demonstrate that with the nanometric precision obtained with AFM microscopy, it is possible to distinguish the different states of preservation, much better than using conventional petrographic methods. The surface's roughness is evaluated from very small artifact's fragments, reducing the coring at micrometric scale with a minimal damage to the artworks. After the diagnosis, we performed restoration tests using the pulsed laser ablation (PLA) method and compared it with the more common micro-sandblasting under dry conditions. We find that the PLA is highly effective for the removal of the surficial patina, with a control of a few hundreds of nanometers in the cleaning of surface, without introducing chemical or morphological damages to the artifacts. Moreover, PLA can be easily implemented in underwater conditions; this has the great advantage that stone and pottery artifacts for marine archeological sites do not need to be removed from the site.

  8. A Ramsey’s Method With Pulsed Neutrons for a T-Violation Experiment

    PubMed Central

    Masuda, Y.; Ino, T.; Muto, S.; Skoy, V.

    2005-01-01

    A Ramsey’s method with pulsed neutrons is discussed for neutron spin manipulation in a time reversal (T) symmetry violation experiment. The neutron spin (sn) is aligned to the direction of a vector product of the nuclear spin (I) and the neutron momentum (kn) for the measurement of a T-odd correlation term, which is represented as sn · (kn × I), during propagation through a polarized nuclear target. The phase control and amplitude modulation of separated oscillatory fields are discussed for the measurement of the T-odd correlation term. PMID:27308171

  9. Pulse retrieval in frequency-resolved optical gating based on the method of generalized projections

    SciTech Connect

    DeLong, K.W.; Fittinghoff, D.N.; Trebino, R. ); Kohler, B.; Wilson, K. )

    1994-12-15

    We use the algorithmic method of generalized projections (GP's) to retrieve the intensity and phase of an ultrashort laser pulse from the experimental trace in frequency-resolved optical gating (FROG). Using simulations, we show that the use of GP's improves significantly the convergence properties of the algorithm over the basic FROG algorithm. In experimental measurements, the GP-based algorithm achieves significantly lower errors than previous algorithms. The use of GP's also permits the inclusion of an arbitrary material response function in the FROG problem.

  10. A method for localized computation of Pulse Wave Velocity in carotid structure.

    PubMed

    Patil, Ravindra B; Krishnamoorthy, P; Sethuraman, Shriram

    2015-08-01

    Pulse Wave Velocity (PWV) promises to be a useful clinical marker for noninvasive diagnosis of atherosclerosis. This work demonstrates the ability to perform localized carotid PWV measurements from the distention waveform derived from the Radio Frequency (RF) ultrasound signal using a carotid phantom setup. The proposed system consists of low cost custom-built ultrasound probe and algorithms for envelope detection, arterial wall identification, echo tracking, distension waveform computation and PWV estimation. The method is proposed on a phantom data acquired using custom-built prototype non-imaging probe. The proposed approach is non-image based and can be seamlessly integrated into existing clinical ultrasound scanners. PMID:26736653

  11. Noncontact single-pulse optical method to measure interfacial properties in intact systems.

    PubMed

    Clark, David C; Kim, Myung K

    2012-12-15

    We introduce a noncontact purely optical approach to measuring the localized surface properties of an interface within a system using a single optical pressure pulse and a time-resolved digital holographic quantitative phase-imaging technique to track the propagating nanometric capillary disturbance. We demonstrate the proposed method's ability to measure the surface energy of deionized water, methanol, and chemical monolayers formed by surfactants with good agreement to published values. The development of this technique boasts immediate application to static and dynamic systems and near-future applications for living biological cell membranes. PMID:23258033

  12. A Heuristic Fast Method to Solve the Nonlinear Schroedinger Equation in Fiber Bragg Gratings with Arbitrary Shape Input Pulse

    SciTech Connect

    Emami, F.; Hatami, M.; Keshavarz, A. R.; Jafari, A. H.

    2009-08-13

    Using a combination of Runge-Kutta and Jacobi iterative method, we could solve the nonlinear Schroedinger equation describing the pulse propagation in FBGs. By decomposing the electric field to forward and backward components in fiber Bragg grating and utilizing the Fourier series analysis technique, the boundary value problem of a set of coupled equations governing the pulse propagation in FBG changes to an initial condition coupled equations which can be solved by simple Runge-Kutta method.

  13. Determination of pure neutron radiolysis yields for use in chemical modeling of supercritical water

    NASA Astrophysics Data System (ADS)

    Edwards, Eric J.

    This work has determined pure neutron radical yields at elevated temperature and pressure up to supercritical conditions using a reactor core radiation. The data will be necessary to provides realistic conditions for material corrosion experiments for the supercritical water reactor (SCWR) through water chemistry modeling. The work has been performed at the University of Wisconsin Nuclear Reactor using an apparatus designed to transport supercritical water near the reactor core. Low LET yield data used in the experiment was provided by a similar project at the Notre Dame Radiation Lab. Radicals formed by radiolysis were measured through chemical scavenging reactions. The aqueous electron was measured by two methods, a reaction with N2O to produce molecular nitrogen and a reaction with SF6 to produce fluoride ions. The hydrogen radical was measured through a reaction with ethanol-D6 (CD3CD2OD) to form HD. Molecular hydrogen was measured directly. Gaseous products were measured with a mass spectrometer and ions were measured with an ion selective electrode. Radiation energy deposition was calibrated for neutron and gamma radiation separately with a neutron activation analysis and a radiolysis experiment. Pure neutron yields were calculated by subtracting gamma contribution using the calibrated gamma energy deposition and yield results from work at the Notre Dame Radiation Laboratory. Pure neutron yields have been experimentally determined for aqueous electrons from 25°C to 400°C at 248 bar and for the hydrogen radical from 25°C to 350°C at 248 bar, Isothermal data has been acquired for the aqueous electron at 380°C and 400°C as a function of density. Molecular hydrogen yields were measured as a function of temperature and pressure, although there was evidence that chemical reactions with the walls of the water tubing were creating molecular hydrogen in addition to that formed through radiolysis. Critical hydrogen concentration behavior was investigated but a

  14. Pulsed arrays: A new method of flaw detection by generating a frequency dependent angle of propagation

    NASA Astrophysics Data System (ADS)

    Hill, S. J.; Dixon, S. M.

    2012-05-01

    A new method of using an array of generation sources, pulsed simultaneously to generate a wavefront with a frequency dependant angle of propagation, has been developed. If pulsed arrays are used to generate a wave with a frequency dependent angle of propagation, the angle at which the wave was launched can be identified by measuring the frequency of the detected wave. In an isotropic material this means that it is possible use a second transducer to locate the position of the scatterer, whereas with a conventional single element generator method, it can only be located onto an ellipse. In addition to an increased scan speed, the resolution of detection should also be improved. A theoretical framework is put forward to explain how the wavefront is created from the superposition of the waves from the individual elements, and how the frequency varies along the wavefront. Finite element models and experimental measurements were also carried out, and both agreed with the analytic model. This method will have applications within NDE, but could also extend to sonar and radar techniques.

  15. Method and apparatus for enhancing surface absorption and emissivity in optical pulsed infrared nondestructive evaluation

    NASA Astrophysics Data System (ADS)

    Duan, Yuxia; Zhang, Cunlin; Jin, Wanping; Wu, Naiming

    2009-07-01

    In the application of optical pulsed infrared NDE, the visible light absorption and IR emissivity of the detected object must be considered. One of the simple methods is spraying paint on the highly reflective and low IR emissivity surface before testing. However, for some materials such as with pore space in the surface or easily to be corrupted have to be pretreated by other method and apparatus. Two kinds of apparatus for surface pretreating are designed according to the dimension of the detected object and the testing conditions. One apparatus is independent of the former detecting system, and the other is an improvement of the former system. The basic principle of the two apparatus is covering a flexible membrane of high light absorption and IR emissivity on the specimen surface by vacuum pumping. The paper also present the applications of the method, including the detection of the metal mesh material and the honeycomb structures with aluminum coating. The experimental results show that the technique of covering thin film by vacuum pump is effective for enhancing surface absorption and emissivity; moreover, it does not pollute or damage the sample. The application of the technique has practical significance, because it extends the scope of the application of the optical pulsed thermography nondestructive evaluation.

  16. Calculation of photon pulse height distribution using deterministic and Monte Carlo methods

    NASA Astrophysics Data System (ADS)

    Akhavan, Azadeh; Vosoughi, Naser

    2015-12-01

    Radiation transport techniques which are used in radiation detection systems comprise one of two categories namely probabilistic and deterministic. However, probabilistic methods are typically used in pulse height distribution simulation by recreating the behavior of each individual particle, the deterministic approach, which approximates the macroscopic behavior of particles by solution of Boltzmann transport equation, is being developed because of its potential advantages in computational efficiency for complex radiation detection problems. In current work linear transport equation is solved using two methods including collided components of the scalar flux algorithm which is applied by iterating on the scattering source and ANISN deterministic computer code. This approach is presented in one dimension with anisotropic scattering orders up to P8 and angular quadrature orders up to S16. Also, multi-group gamma cross-section library required for this numerical transport simulation is generated in a discrete appropriate form. Finally, photon pulse height distributions are indirectly calculated by deterministic methods that approvingly compare with those from Monte Carlo based codes namely MCNPX and FLUKA.

  17. X-ray pulse preserving single-shot optical cross-correlation method for improved experimental temporal resolution

    SciTech Connect

    Beye, M.; Krupin, O.; Hays, G.; Jong, S. de; Lee, S.; Coffee, R.; Holmes, M. R.; Fry, A. R.; White, W. E.; Bostedt, C.; Schlotter, W. F.; Reid, A. H.; Rupp, D.; Lee, W.-S.; Scherz, A. O.; Chuang, Y.-D.; Cryan, J. P.; Glownia, J. M.; Foehlisch, A.; Durr, H. A.

    2012-03-19

    We measured the relative arrival time between an optical pulse and a soft x-ray pulse from a free-electron laser. This femtosecond cross-correlation measurement was achieved by observing the change in optical reflectivity induced through the absorption of a fraction of the x-ray pulse. The main x-ray pulse energy remained available for an independent pump-probe experiment where the sample may be opaque to soft x-rays. The method was employed to correct the two-pulse delay data from a canonical pump-probe experiment and demonstrate 130 {+-} 20 fs (FWHM) temporal resolution. We further analyze possible timing jitter sources and point to future improvements.

  18. Long pulse generation technology of solid-state laser adopting a new real time multi-discharge method

    NASA Astrophysics Data System (ADS)

    Hong, Jung-Hwan; Song, Kum-Young; Chung, Hyun-Ju; Jung, Jong-Han; Kim, Whi-Young; Kang, Uk; Kim, Hee-Je

    2002-04-01

    In this study, a solid-state laser system adopting a new real time multi-discharge method in which three flashlamps are turned on consecutively was designed and fabricated to examine the pulse width and the pulse shape of the laser beams depending upon the changes in the lamp turn-on time. That is, this study shows a technology that makes it possible to make various pulse shapes by turning on three flashlamps consecutively on a real-time basis with the aid of a program integrated circuit one-chip microprocessor. With this technique, the lamp turn-on delay time can be varied more diversely from 0 to 10 ms and the real-time control is possible with an external keyboard, enabling various pulse shapes. In addition, longer pulses can be more widely used for industrial processing and many medical purposes.

  19. Calibration of pulsed electroacoustic method considering electrode-dielectric interface status and porosity

    NASA Astrophysics Data System (ADS)

    Huang, Meng; Zhou, Yuanxiang; Chen, Weijiang; Lu, Licheng; Jin, Fubao; Huang, Jianwen

    2014-10-01

    Pulsed electroacoustic (PEA) method is widely used, but measurement conditions not always agree with the underlying PEA assumptions. This necessitates space charge recovery; however, existing research only addresses the attenuation and dispersion in lossy media. The effects of electrode-dielectric interface contact status and porosity on the accuracy of space charge distribution are discussed in the present article. It is shown that the presence of nonlinear interface and porosity can introduce severe error. However, because the properties of acoustic propagation of waves (which are generated from charge on the electrode and in the bulk) are different, the conventional recovery algorithm is no longer suitable for calibrating the charge density. To obtain accurate space charge profiles, it is necessary to eliminate these effects. A method has been proposed which is based on the original measurement process. The validity of the proposed method was tested by reasonable post-recovery electric field distributions.

  20. Thermal property measurement for thermal barrier coatings using pulsed thermal imaging - multilayer analysis method

    NASA Astrophysics Data System (ADS)

    Sun, J. G.; Tao, N.

    2016-02-01

    Thermal barrier coatings (TBCs) are extensively used on hot gas-path components in gas turbines to improve engine performance and extend component life. TBC thermal properties, specifically the thermal conductivity and heat capacity (the product of density and specific heat), are important parameters in these applications. These TBC properties are usually measured by destructive methods with specially prepared TBC samples. Nondestructive evaluation (NDE) methods have been developed in recently years that can measure TBC properties on natural TBC samples. However, many have limitations when examining TBCs on engine components. One exception is the pulsed thermal imaging - multilayer analysis (PTI-MLA) method, which can be applied to essentially any TBC samples with one or more coating layers and can determine TBC property distributions over the entire TBC surface. This paper describes its basic theories and implementations and discusses its potential applications to all areas of TBC studies.

  1. On study fine atmospheric structure by using of the method of decomposition of infrasonic signals from pulsed sources

    NASA Astrophysics Data System (ADS)

    Kulichkov, Sergey; Chunchuzov, Igor; Demin, Dmitry

    2016-04-01

    The proposed method are based on the decomposition of infrasonic signals from pulse sources. In this method, the recorded infrasonic signal is modeled by the sequence of single acoustic pulse having the form of a U and N waves. Each pulse U and N wave corresponds to the reflection of sound from atmospheric inhomogeneities at different altitudes in the atmosphere. By determining time intervals between such pulses U and N waves it is possible to determine vertical gradients of the effective sound speed at the different altitudes in the atmosphere. The method to determine the vertical profiles of the vertical gradients of effective sound velocity in the atmosphere by using data from infrasound monitoring are proposed. The obtained data are corresponds to the theory of the fine structure in the upper atmosphere.

  2. Note: A method for correction of finite pulse time effects in flash diffusivity measurements of thin films

    NASA Astrophysics Data System (ADS)

    Tao, Ye; Yang, Liping; Zhong, Qiu; Xu, Zijun; Luo, Caiyun

    2016-08-01

    A data correction method that can reduce finite pulse time effects in the flash method is presented in this article. Based on the physical model of the classical flash method, the present method uses the cutoff time moment of laser heating as zero point. This article investigated the case of constant heat flux heating by using the theoretical method and obtained a new calculation formula. The formula was tested in the case where half temperature rise time is less than the pulse time (i.e., τ0/t0.5 > 1), and the result was satisfactory. Theoretically, this method can correct the effect of any finite pulse time and significantly expand the scope of application of the flash method.

  3. Note: A method for correction of finite pulse time effects in flash diffusivity measurements of thin films.

    PubMed

    Tao, Ye; Yang, Liping; Zhong, Qiu; Xu, Zijun; Luo, Caiyun

    2016-08-01

    A data correction method that can reduce finite pulse time effects in the flash method is presented in this article. Based on the physical model of the classical flash method, the present method uses the cutoff time moment of laser heating as zero point. This article investigated the case of constant heat flux heating by using the theoretical method and obtained a new calculation formula. The formula was tested in the case where half temperature rise time is less than the pulse time (i.e., τ0/t0.5 > 1), and the result was satisfactory. Theoretically, this method can correct the effect of any finite pulse time and significantly expand the scope of application of the flash method. PMID:27587175

  4. Blood pressure monitoring during exercise: comparison of pulse transit time and volume clamp methods.

    PubMed

    Wibmer, Thomas; Denner, Coy; Fischer, Christoph; Schildge, Benedikt; Rüdiger, Stefan; Kropf-Sanchen, Cornelia; Rottbauer, Wolfgang; Schumann, Christian

    2015-01-01

    During physical exercise, pulse transit time (PTT), expressed as the interval between ventricular electrical activity and peripheral pulse wave, may provide a surrogate estimate for blood pressure by the use of specific calibration procedures. The objective of this study was to determine systolic blood pressure (SBP) values derived from the PTT method and from an established method of non-invasive continuous blood pressure measurement based on the volume clamp technique, and to compare their agreement with sphygmomanometry during exercise tests. In 18 subjects, electrocardiogram (ECG) and finger-photoplethysmography were continuously recorded during maximal cycle exercise tests. Intermittent and continuous blood pressure measurements were simultaneously taken using automated sphygmomanometry and a Portapres Model-2 device, respectively. PTT was calculated for each ECG R-wave and the corresponding steepest upstroke slope in the photoplethysmogram, and was transformed to a continuous blood pressure estimate using multipoint nonlinear regression calibration based on the individual subject's sphygmomanometer readings. Bland-Altman limits of agreement between PTT-derived SBP estimates and sphygmomanometer values were -24.7 to 24.1 mmHg, and between Portapres and sphygmomanometer SBP values were -42.0 to 70.1 mmHg. For beat-to-beat SBP estimation during exercise, PTT measurement combined with multipoint nonlinear regression calibration based on intermittent sphygmomanometry may be an alternative to volume clamp devices. PMID:26286887

  5. High performance data compression method with pattern matching for biomedical ECG and arterial pulse waveforms.

    PubMed

    Chen, Wen-Shiung; Hsieh, Lili; Yuan, Shang-Yuan

    2004-04-01

    Biomedical waveforms, such as electrocardiogram (ECG) and arterial pulse, always possess a lot of important clinical information in medicine and are usually recorded in a long period of time in the application of telemedicine. Due to the huge amount of data, to compress the biomedical waveform data is vital. By recognizing the strong similarity and correlation between successive beat patterns in biomedical waveform sequences, an efficient data compression scheme mainly based on pattern matching is introduced in this paper. The waveform codec consists mainly of four units: beat segmentation, beat normalization, two-stage pattern matching and template updating and residual beat coding. Three different residual beat coding methods, such as Huffman/run-length coding, Huffman/run-length coding in discrete cosine transform domain, and vector quantization, are employed. The simulation results show that our compression algorithms achieve a very significant improvement in the performances of compression ratio and error measurement for both ECG and pulse, as compared with some other compression methods. PMID:14992823

  6. High-quality quantum-dot-based full-color display technology by pulsed spray method

    NASA Astrophysics Data System (ADS)

    Chen, Kuo-Ju; Chen, Hsin-Chu; Tsai, Kai-An; Lin, Chien-Chung; Tsai, Hsin-Han; Chien, Shih-Hsuan; Cheng, Bo-Siao; Hsu, Yung-Jung; Shih, Min-Hsiung; Kuo, Hao-Chung

    2013-03-01

    We fabricated the colloidal quantum-dot light-emitting diodes (QDLEDs) with the HfO2/SiO2-distributed Bragg reflector (DBR) structure using a pulsed spray coating method. Moreover, pixelated RGB arrays, 2-in. wafer-scale white light emission, and an integrated small footprint white light device were demonstrated. The experimental results showed that the intensity of red, blue, and green (RGB) emissions exhibited considerable enhancement because of the high reflectivity in the UV region by the DBR structure, which subsequently increased the use in the UV optical pumping of RGB QDs. In this experiment, a pulsed spray coating method was crucial in providing uniform RGB layers, and the polydimethylsiloxane (PDMS) film was used as the interface layer between each RGB color to avoid crosscontamination and self-assembly of QDs. Furthermore, the chromaticity coordinates of QDLEDs with the DBR structure remained constant under various pumping powers in the large area sample, whereas a larger shift toward high color temperatures was observed in the integrated device. The resulting color gamut of the proposed QDLEDs covered an area 1.2 times larger than that of the NTSC standard, which is favorable for the next generation of high-quality display technology.

  7. Pulse-fitting - A novel method for the evaluation of pulse measurements, demonstrated for the low frequency behavior of lithium-ion cells

    NASA Astrophysics Data System (ADS)

    Schmidt, Jan Philipp; Ivers-Tiffée, Ellen

    2016-05-01

    The impedance of a commercial lithium ion cell (2 Ah) is evaluated over a wide frequency range of 10-5 Hz < f < 102 Hz using a new approach. The so-called pulse-fitting method (PFM) derives the cell impedance from time domain measurements, which are transferred into frequency data by a using a newly developed evaluation algorithm in combination with the distribution of relaxation times (DRT). The time constants of the individual polarization processes taking place during charging/discharging were analyzed at 20 different state-of-charge levels at 23 °C in a wide frequency range spanning from 10-5 Hz < f < 102 Hz. The pulse-fitting method seems to be especially useful for monitoring the change of individual polarization losses in the course of time, as self-discharge effects can be sorted out.

  8. A method for the formation of Pt metal nanoparticle arrays using nanosecond pulsed laser dewetting

    NASA Astrophysics Data System (ADS)

    Owusu-Ansah, Ebenezer; Horwood, Corie A.; El-Sayed, Hany A.; Birss, Viola I.; Shi, Yujun J.

    2015-05-01

    Nanosecond pulsed laser dewetting of Pt thin films, deposited on a dimpled Ta (DT) surface, has been studied here in order to form ordered Pt nanoparticle (NP) arrays. The DT substrate was fabricated via a simple electrochemical anodization process in a highly concentrated H2SO4 and HF solution. Pt thin films (3-5 nm) were sputter coated on DT and then dewetted under vacuum to generate NPs using a 355 nm laser radiation (6-9 ns, 10 Hz). The threshold laser fluence to fully dewet a 3.5 nm thick Pt film was determined to be 300 mJ/cm2. Our experiments have shown that shorter irradiation times (≤60 s) produce smaller nanoparticles with more uniform sizes, while longer times (>60 s) give large nanoparticles with wider size distributions. The optimum laser irradiation time of 1 s (10 pulses) has led to the formation of highly ordered Pt nanoparticle arrays with an average nanoparticle size of 26 ± 3 nm with no substrate deformation. At the optimum condition of 1 s and 500 mJ/cm2, as many as 85% of the dewetted NPs were found neatly in the well-defined dimples. This work has demonstrated that pulsed laser dewetting of Pt thin films on a pre-patterned dimpled substrate is an efficient and powerful technique to produce highly ordered Pt nanoparticle arrays. This method can thus be used to produce arrays of other high-melting-point metal nanoparticles for a range of applications, including electrocatalysis, functionalized nanomaterials, and analytical purposes.

  9. A method for the formation of Pt metal nanoparticle arrays using nanosecond pulsed laser dewetting

    SciTech Connect

    Owusu-Ansah, Ebenezer; Horwood, Corie A.; Birss, Viola I.; Shi, Yujun J.; El-Sayed, Hany A.

    2015-05-18

    Nanosecond pulsed laser dewetting of Pt thin films, deposited on a dimpled Ta (DT) surface, has been studied here in order to form ordered Pt nanoparticle (NP) arrays. The DT substrate was fabricated via a simple electrochemical anodization process in a highly concentrated H{sub 2}SO{sub 4} and HF solution. Pt thin films (3–5 nm) were sputter coated on DT and then dewetted under vacuum to generate NPs using a 355 nm laser radiation (6–9 ns, 10 Hz). The threshold laser fluence to fully dewet a 3.5 nm thick Pt film was determined to be 300 mJ/cm{sup 2}. Our experiments have shown that shorter irradiation times (≤60 s) produce smaller nanoparticles with more uniform sizes, while longer times (>60 s) give large nanoparticles with wider size distributions. The optimum laser irradiation time of 1 s (10 pulses) has led to the formation of highly ordered Pt nanoparticle arrays with an average nanoparticle size of 26 ± 3 nm with no substrate deformation. At the optimum condition of 1 s and 500 mJ/cm{sup 2}, as many as 85% of the dewetted NPs were found neatly in the well-defined dimples. This work has demonstrated that pulsed laser dewetting of Pt thin films on a pre-patterned dimpled substrate is an efficient and powerful technique to produce highly ordered Pt nanoparticle arrays. This method can thus be used to produce arrays of other high-melting-point metal nanoparticles for a range of applications, including electrocatalysis, functionalized nanomaterials, and analytical purposes.

  10. Application of the Monte Carlo method for modeling passage of ultrashort laser pulses through an inhomogeneous medium with moving scatterers

    NASA Astrophysics Data System (ADS)

    Starukhin, P. Yu.; Klinaev, Yu. V.

    2011-05-01

    We present the results of numerical modeling of passage of ultrashort laser pulses through an inhomogeneous layered medium with moving scatterers, based on solution of the nonsteady-state radiation transport equation by the Monte Carlo method. We consider the effects of Doppler broadening of the backscattered radiation spectrum in biological tissues. We have analyzed the dynamics of propagation of a short laser pulse within a multilayer model of human skin. We have studied the possibilities for tomography of different layers of biological tissue based on analysis of the spectrum of the scattered radiation pulse.

  11. Vitroceramic interface deposited on titanium substrate by pulsed laser deposition method.

    PubMed

    Voicu, Georgeta; Miu, Dana; Dogaru, Ionut; Jinga, Sorin Ion; Busuioc, Cristina

    2016-08-30

    Pulsed laser deposition (PLD) method was used to obtain biovitroceramic thin film coatings on titanium substrates. The composition of the targets was selected from SiO2-CaO-P2O5-(CaF2) systems and the corresponding masses were prepared using the sol-gel method. The depositions were performed in oxygen atmosphere (100mTorr), while the substrates were heated at 400°C. The PLD deposited films were analysed through different experimental techniques: X-ray diffraction, scanning (SEM, EDX) and transmission (HRTEM, SAED) electron microscopy and infra-red spectroscopy coupled with optical microscopy. They were also biologically tested by in vitro cell culture and the contact angle was determined. The bioevaluation results indicate a high biocompatibilty of the obtained materials, demonstrating their potential use for biomedical applications. PMID:26546909

  12. Radiolysis of ethanol and ethanol-water solutions: A tool for studying bioradical reactions

    NASA Astrophysics Data System (ADS)

    Jore, D.; Champion, B.; Kaouadji, N.; Jay-Gerin, J.-P.; Ferradini, C.

    Radiolysis of pure ethanol and ethanol-water solutions is examined in view of its relevance to the study of biological radical mechanisms. On the basis of earlier studies, a consistent reaction scheme is adopted. New data on radical yields are obtained from the radiolysis of dilute solutions of vitamins E and C in these solvents. It is shown that the radiolysis of ethanolic solutions provide an efficient tool to study radical reactions of water-insoluble biomolecules.

  13. Volume Ice Radiolysis in the Outer Solar System

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.; Cooper, P. D.

    2006-05-01

    The primary energy flux of charged particle components of the heliospheric and magnetospheric environments of the solar system is primarily carried by highly penetrating energetic particles. Although laboratory experiments on production of organics and oxidants typically only address effects on very thin surface layers, energy deposition occurs on surfaces of icy bodies of the outer solar system to meters in depth. Time scales for significant radiolytic deposition vary from thousands of years at millimeter depths on Europa to billions of years in the meters-deep regolith of Kuiper Belt Objects. Radioisotope decay (e.g., K-40) also contributes to volume radiolysis as the only energy source at much greater depths. Radiolytic oxygen is a potential resource for life within Europa and a partial source of oxygen for Saturn's magnetosphere and Titan's upper atmosphere. Interactions of very high energy cosmic rays with ices at Titan's surface may provide one of the few sources of oxidants in that organic-rich environment. The red colors of low-inclination classical Kuiper Belt Objects at 40- 50 AU, and Centaur objects originating from this same population, may arise from volume radiolysis of deep ice layers below more refractory radiation crusts eroded away by surface sputtering and micrometeoroid impacts. A variety of techniques are potentially available to measure volume radiolysis products and have been proposed for study as part of the new Space Physics of Life initiative at NASA Goddard Space Flight Center. The technique of Electron Paramagnetic Resonance (EPR) has been used in medical studies to measure oxidant production in irradiated human tissue for cancer treatment. Other potential techniques include optical absorption spectroscopy and standard wet chemical analysis. These and other potential techniques are briefly reviewed for applicability to problems in solar system ice radiolysis and astrobiology.

  14. Stacking gels: A method for maximising output for pulsed-field gel electrophoresis.

    PubMed

    Heng, See Kah; Heng, Chua Kek; Puthucheary, S D

    2009-01-01

    Pulsed field gel electrophoresis (PFGE), the gold standard of molecular typing methods, has a major disadvantage of an unusually long electrophoretic time. From the original protocol of 6 days, it was modified to 3 days and subsequently to a single day. We describe the procedure of stacking five to six gels one on top of another in order to increase and maximize the output in a shorter time without compromising the resolution and reproducibility. All the variables that affect pulsed field gels during electrophoresis were taken into consideration. We firstly optimized the parameters to be used and secondly determined whether stacking of five to six gels had any effect on the molecular separation during electrophoresis in comparison with a single gel run. DNA preparation, restriction, electrophoresis, staining and gel documentation was carried out based on previously published methods. Gels were analysed using BioNumerics and dice coefficient and unweighted pair group methods were used to generate dendrograms based on 1.5% tolerance values. Identical band profiles and band resolution-separation were seen in the PFGE patterns with single gel and multiple stacking gels. Cluster analysis further strengthened the fact that results from stacking gels were reproducible and comparable with a single gel run. This method of stacking gels saves time and maximizes the output at the same time. The run time for a single gel was about 28 hours, but with six stacked gels the run time was 54 hours compared with 28 x 6 = 168 hours if they were run separately as single gels thus saving time of 67.86%. Beside the big factor of saving time, stacking gels save resources (electricity, reagents, water, chemicals and working time) by increasing the sample throughput in a shorter time without compromising on quality of data. But optimization of working parameters is vital depending on the PFGE system used. PMID:19384038

  15. Radiolysis of simple quaternary ammonium salt components of Amberlite resin

    NASA Astrophysics Data System (ADS)

    Dhiman, Surajdevprakash B.; LaVerne, Jay A.

    2013-05-01

    The radiation chemical yields of gaseous products, H2 and CH4, in the radiolysis of dry methylammonium chloride, dimethylammonium chloride, trimethylammonium chloride, tetramethylammonium chloride and benzyl trimethylammonium chloride by γ-rays and 5 MeV helium ions have been investigated. Some of these amines are the different components of the quaternary ammonium resin Amberlite, which is a strongly basic anion exchange resin based on a polystyrene divinylbenzene copolymer. Molecular hydrogen yields with γ-radiolysis range from a high of 4.43 molecules per 100 eV for trimethylammonium chloride to 0.07 and 0.05 molecules per 100 eV for tetramethylammonium chloride and benzyl trimethylammonium chloride, respectively. Yields of methane gas are generally negligible except for trimethylammonium chloride and tetramethylammonium chloride, 0.26 and 0.02 molecules per 100 eV, respectively. Isotopic labeling studies suggest that the first step in H2 production is the breakage of the Nsbnd H bond followed by abstraction of Hrad atom from the methyl groups. EPR analysis shows the formation of both N and C centered radicals. A comparison is made between the radiolysis of Amberlite and its various components.

  16. Radiolysis and Photolysis of Icy Satellite Surfaces: Experiments and Theory

    NASA Technical Reports Server (NTRS)

    Cassidy, T.; Coll, P.; Raulin, F.; Carlson, R. W.; Hand, K. P.; Johnson, R. E.; Loeffler, M. J.; Baragiola, R. A.

    2010-01-01

    The transport and exchange of material between bodies in the outer solar system is often facilitated by their exposure to ionizing radiation. With this in mind we review the effects of energetic ions, electrons and UV photons on materials present in the outer solar system. We consider radiolysis, photolysis, and sputtering of low temperature solids. Radiolysis and photolysis are the chemistry that follows the bond breaking and ionization produced by incident radiation, producing, e.g., O2 and H2 from irradiated H2O ice. Sputtering is the ejection of molecules by incident radiation. Both processes are particularly effective on ices in the outer solar system. Materials reviewed include H2O ice, sulfur-containing compounds (such as S02 and S8), carboncontajning compounds (such as CH4), nitrogen-containing compounds (such as NH3 and N2), and mixtures of those compounds. We also review the effects of ionizing radiation on a mixture of N2 and CH4 gases, as appropriate to Titan's upper atmosphere, where radiolysis and photolysis produce complex organic compounds (tholins).

  17. Method for producing H.sub.2 using a rotating drum reactor with a pulse jet heat source

    DOEpatents

    Paulson, Leland E.

    1990-01-01

    A method of producing hydrogen by an endothermic steam-carbon reaction using a rotating drum reactor and a pulse jet combustor. The pulse jet combustor uses coal dust as a fuel to provide reaction temperatures of 1300.degree. to 1400.degree. F. Low-rank coal, water, limestone and catalyst are fed into the drum reactor where they are heated, tumbled and reacted. Part of the reaction product from the rotating drum reactor is hydrogen which can be utilized in suitable devices.

  18. Multi-beam pulsed laser deposition: new method of making nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Darwish, Abdalla M.; Wilson, Simeon; Blackwell, Ashely; Taylor, Keylantra; Sarkisov, Sergey; Patel, Darayas; Mele, Paolo; Koplitz, Brent

    2015-08-01

    Huge number of new photonic devices, including light emitters, chemical sensors, and energy harvesters, etc. can be made of the nanocomposite coatings produced by the new multi-beam pulsed laser deposition (MB-PLD) process. We provide a short review of the conventional single-beam PLD method and explain why it is poorly suitable for making nanocomposite coatings. Then we describe the new MB-PLD process and system, particularly the multiple-beam matrix assisted pulsed laser evaporation (MB-MAPLE) version with laser beam scanning and plume direction control. The latter one is particularly designed to make organic (polymer) - inorganic functionalized nanocomposite coatings. Polymer film serves as a host for inorganic nanoparticles that add a specific functionality to the film. We analyze the properties of such coatings using the examples of poly(methyl methacrylate) (PMMA) films impregnated with the nanoparticles of rare-earth (RE) upconversion phosphors. They demonstrated the preservation of microcrystalline structure and bright upconversion emission in visible region of the phosphor nanoparticles after they were transferred in the polymer matrix during the MB-MAPLE process. The proposed technology has thus proven to serve its purpose: to make functionalized polymer nanocomposite coatings for a various potential applications.

  19. Pulse-echo ultrasonic imaging method for eliminating sample thickness variation effects

    NASA Technical Reports Server (NTRS)

    Roth, Don J. (Inventor)

    1995-01-01

    A pulse-echo, immersion method for ultrasonic evaluation of a material is discussed. It accounts for and eliminates nonlevelness in the equipment set-up and sample thickness variation effects employs a single transducer, automatic scanning and digital imaging to obtain an image of a property of the material, such as pore fraction. The nonlevelness and thickness variation effects are accounted for by pre-scan adjusments of the time window to insure that the echoes received at each scan point are gated in the center of the window. This information is input into the scan file so that, during the automatic scanning for the material evaluation, each received echo is centered in its time window. A cross-correlation function calculates the velocity at each scan point, which is then proportionalized to a color or grey scale and displayed on a video screen.

  20. Apparatus and method for pulsed laser deposition of materials on wires and pipes

    NASA Technical Reports Server (NTRS)

    Fernandez, Felix E. (Inventor)

    2003-01-01

    Methods and apparatuses are disclosed which allow uniform coatings to be applied by pulsed laser deposition (PLD) on inner and outer surfaces of cylindrical objects, such as rods, pipes, tubes, and wires. The use of PLD makes this technique particularly suitable for complex multicomponent materials, such as superconducting ceramics. Rigid objects of any length, i.e., pipes up to a few meters, and with diameters from less than 1 centimeter to over 10 centimeters can be coated using this technique. Further, deposition is effected simultaneously onto an annular region of the pipe wall. This particular arrangement simplifies the apparatus, reduces film uniformity control difficulties, and can result in faster operation cycles. In addition, flexible wires of any length can be continuously coated using the disclosed invention.

  1. Method for continuous control of composition and doping of pulsed laser deposited films

    DOEpatents

    Lowndes, Douglas H.; McCamy, James W.

    1995-01-01

    A method for growing a deposit upon a substrate of semiconductor material involves the utilization of pulsed laser deposition techniques within a low-pressure gas environment. The substrate and a target of a first material are positioned within a deposition chamber and a low-pressure gas atmosphere is developed within the chamber. The substrate is then heated, and the target is irradiated, so that atoms of the target material are ablated from the remainder of the target, while atoms of the gas simultaneously are adsorbed on the substrate/film surface. The ablated atoms build up upon the substrate, together with the adsorbed gas atoms to form the thin-film deposit on the substrate. By controlling the pressure of the gas of the chamber atmosphere, the composition of the formed deposit can be controlled, and films of continuously variable composition or doping can be grown from a single target of fixed composition.

  2. Method for continuous control of composition and doping of pulsed laser deposited films by pressure control

    DOEpatents

    Lowndes, Douglas H.; McCamy, James W.

    1996-01-01

    A method for growing a deposit upon a substrate of semiconductor material involves the utilization of pulsed laser deposition techniques within a low-pressure gas environment. The substrate and a target of a first material are positioned within a deposition chamber and a low-pressure gas atmosphere is developed within the chamber. The substrate is then heated, and the target is irradiated, so that atoms of the target material are ablated from the remainder of the target, while atoms of the gas simultaneously are adsorbed on the substrate/film surface. The ablated atoms build up upon the substrate, together with the adsorbed gas atoms to form the thin-film deposit on the substrate. By controlling the pressure of the gas of the chamber atmosphere, the composition of the formed deposit can be controlled, and films of continuously variable composition or doping can be grown from a single target of fixed composition.

  3. Method and apparatus for the control of fluid dynamic mixing in pulse combustors

    DOEpatents

    Bramlette, T. Tazwell; Keller, Jay O.

    1992-06-02

    In a method and apparatus for controlling total ignition delay time in a pulse combustor, and thus controlling the mixing characteristics of the combustion reactants and the combustion products in the combustor, the total ignition delay time is controlled by adjusting the inlet geometry of the inlet to the combustion chamber. The inlet geometry may be fixed or variable for controlling the mixing characteristics. A feedback loop may be employed to sense actual combustion characteristics, and, in response to the sensed combustion characteristics, the inlet geometry may be varied to obtain the total ignition delay time necessary to achieve the desired combustion characteristics. Various embodiments relate to the varying of the mass flow rate of reactants while holding the radius/velocity ratio constant.

  4. Method and apparatus for the control of fluid dynamic mixing in pulse combustors

    DOEpatents

    Bramlette, T.T.; Keller, J.O.

    1992-06-02

    In a method and apparatus for controlling total ignition delay time in a pulse combustor, and thus controlling the mixing characteristics of the combustion reactants and the combustion products in the combustor, the total ignition delay time is controlled by adjusting the inlet geometry of the inlet to the combustion chamber. The inlet geometry may be fixed or variable for controlling the mixing characteristics. A feedback loop may be employed to sense actual combustion characteristics, and, in response to the sensed combustion characteristics, the inlet geometry may be varied to obtain the total ignition delay time necessary to achieve the desired combustion characteristics. Various embodiments relate to the varying of the mass flow rate of reactants while holding the radius/velocity ratio constant. 10 figs.

  5. Pulse-Echo Ultrasonic Imaging Method for Eliminating Sample Thickness Variation Effects

    NASA Technical Reports Server (NTRS)

    Roth, Don J. (Inventor)

    1997-01-01

    A pulse-echo, immersion method for ultrasonic evaluation of a material which accounts for and eliminates nonlevelness in the equipment set-up and sample thickness variation effects employs a single transducer and automatic scanning and digital imaging to obtain an image of a property of the material, such as pore fraction. The nonlevelness and thickness variation effects are accounted for by pre-scan adjustments of the time window to insure that the echoes received at each scan point are gated in the center of the window. This information is input into the scan file so that, during the automatic scanning for the material evaluation, each received echo is centered in its time window. A cross-correlation function calculates the velocity at each scan point, which is then proportionalized to a color or grey scale and displayed on a video screen.

  6. Pulsed digital holography for high-speed contouring that uses a two-wavelength method.

    PubMed

    Pedrini, G; Fröning, P; Tiziani, H J; Gusev, M E

    1999-06-01

    A two-wavelength method for a fast shape measurement by use of a pulsed ruby laser is presented. The wavelength change is produced by alteration of the distance between the plates of the laser's output etalon. One plate of the etalon is mounted on a vibrating piezoelectric element; this allows a fast wavelength change. Two holograms at different wavelengths are recorded in a few microseconds by use of a CCD. The holograms are reconstructed digitally, and the wave-front phase is calculated. The shape is obtained by subtraction of the phases of the wave fronts recorded at different wavelengths. Environmental disturbances at low frequencies, such as air turbulence, vibrations, and object drift, have no influence on the measurement. Experimental results are presented. PMID:18319945

  7. Amplifiable DNA from Gram-negative and Gram-positive bacteria by a low strength pulsed electric field method

    PubMed Central

    Vitzthum, Frank; Geiger, Georg; Bisswanger, Hans; Elkine, Bentsian; Brunner, Herwig; Bernhagen, Jürgen

    2000-01-01

    An efficient electric field-based procedure for cell disruption and DNA isolation is described. Isoosmotic suspensions of Gram-negative and Gram-positive bacteria were treated with pulsed electric fields of <60 V/cm. Pulses had an exponential decay waveform with a time constant of 3.4 µs. DNA yield was linearly dependent on time or pulse number, with several thousand pulses needed. Electrochemical side-effects and electrophoresis were minimal. The lysates contained non-fragmented DNA which was readily amplifiable by PCR. As the method was not limited to samples of high specific resistance, it should be applicable to physiological fluids and be useful for genomic and DNA diagnostic applications. PMID:10734214

  8. Determination of Bosentan in Pharmaceutical Preparations by Linear Sweep, Square Wave and Differential Pulse Voltammetry Methods

    PubMed Central

    Atila, Alptug; Yilmaz, Bilal

    2015-01-01

    In this study, simple, fast and reliable cyclic voltammetry (CV), linear sweep voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) methods were developed and validated for determination of bosentan in pharmaceutical preparations. The proposed methods were based on electrochemical oxidation of bosentan at platinum electrode in acetonitrile solution containing 0.1 M TBACIO4. The well-defined oxidation peak was observed at 1.21 V. The calibration curves were linear for bosentan at the concentration range of 5-40 µg/mL for LSV and 5-35 µg/mL for SWV and DPV methods, respectively. Intra- and inter-day precision values for bosentan were less than 4.92, and accuracy (relative error) was better than 6.29%. The mean recovery of bosentan was 100.7% for pharmaceutical preparations. No interference was found from two tablet excipients at the selected assay conditions. Developed methods in this study are accurate, precise and can be easily applied to Tracleer and Diamond tablets as pharmaceutical preparation. PMID:25901151

  9. Numerical assessment of time-domain methods for the estimation of local arterial pulse wave speed.

    PubMed

    Alastruey, Jordi

    2011-03-15

    A local estimation of pulse wave speed c, an important predictor of cardiovascular events, can be obtained at arterial locations where simultaneous measurements of blood pressure (P) and velocity (U), arterial diameter (D) and U, flow rate (Q) and cross-sectional area (A), or P and D are available, using the PU-loop, sum-of-squares (∑(2)), lnDU-loop, QA-loop or new D(2)P-loop methods. Here, these methods were applied to estimate c from numerically generated P, U, D, Q and A waveforms using a visco-elastic one-dimensional model of the 55 larger human systemic arteries in normal conditions. Theoretical c were calculated from the parameters of the model. Estimates of c given by the loop methods were closer to theoretical values and more uniform within each arterial segment than those obtained using the ∑(2). The smaller differences between estimates and theoretical values were obtained using the D(2)P-loop method, with root-mean-square errors (RMSE) smaller than 0.18 ms(-1), followed by averaging the two c given by the PU- and lnDU-loops (RMSE <2.99 ms(-1)). In general, the errors of the PU-, lnDU- and QA-loops decreased at locations where visco-elastic effects were small and nearby junctions were well-matched for forward-travelling waves. The ∑(2) performed better at proximal locations. PMID:21211799

  10. Cross modulation method of transformation of the spatial coherence of pulsed laser radiation in a nonlinear medium

    SciTech Connect

    Kitsak, M A; Kitsak, A I

    2008-04-30

    The cross modulation method of transformation of the spatial coherence of low-power pulsed laser radiation in a nonlinear medium is proposed. The method is realised experimentally in a multimode optical fibre. The estimates of the degree of spatial coherence of radiation subjected to the phase cross modulation demonstrated the high efficiency of this radiation decorrelation mechanism. (control of laser radiation parameters)

  11. Circuit-field coupled finite element analysis method for an electromagnetic acoustic transducer under pulsed voltage excitation

    NASA Astrophysics Data System (ADS)

    Hao, Kuan-Sheng; Huang, Song-Ling; Zhao, Wei; Wang, Shen

    2011-06-01

    This paper presents an analytical method for electromagnetic acoustic transducers (EMATs) under voltage excitation and considers the non-uniform distribution of the biased magnetic field. A complete model of EMATs including the non-uniform biased magnetic field, a pulsed eddy current field and the acoustic field is built up. The pulsed voltage excitation is transformed to the frequency domain by fast Fourier transformation (FFT). In terms of the time harmonic field equations of the EMAT system, the impedances of the coils under different frequencies are calculated according to the circuit-field coupling method and Poynting's theorem. Then the currents under different frequencies are calculated according to Ohm's law and the pulsed current excitation is obtained by inverse fast Fourier transformation (IFFT). Lastly, the sequentially coupled finite element method (FEM) is used to calculate the Lorentz force in the EMATs under the current excitation. An actual EMAT with a two-layer two-bundle printed circuit board (PCB) coil, a rectangular permanent magnet and an aluminium specimen is analysed. The coil impedances and the pulsed current are calculated and compared with the experimental results. Their agreement verified the validity of the proposed method. Furthermore, the influences of lift-off distances and the non-uniform static magnetic field on the Lorentz force under pulsed voltage excitation are studied.

  12. Detection of volatile impurities in turbine oils by the heat-pulse testing method

    NASA Astrophysics Data System (ADS)

    Skripov, P. V.; Demin, V. A.; Shangin, V. V.; Starostin, A. A.

    2016-07-01

    The research is aimed at development and implementation of methods and devices to control critical sections of the oil system of the power equipment that operates in the real time mode. The task was to develop a method for rapid detection of volatile impurities in turbine oils. The approach to the study is based on quantitative assessment of the short-term thermal stability of the substance that is formally associated with the content of the volatile impurity. The approach was selected on the basis of the results of search experiments taking into consideration the formulation of requirements for the method and the device, viz., (1) the method should reliably determine the moisture content in the range of 10-150 g of the impurity per ton of oil and (2) the device is to be applicable "in situ." For this purpose, a variant of the method of the controlled pulse heating of a wire probe, a resistance thermometer, has been developed. The advantages of the method are its speed, sensitivity to small contents of volatile impurities regardless of the nature of the impurity, and smallness of methodologically contributed perturbation. The heating conditions of the probe most sensitive to the appearance of moisture— including its trace amounts—in the system, has been defined. The duration of the measurement is on the order of milliseconds; the heat flux density through the surface of the probe reaches 1 MW/m2. The essence of the method consists in measuring, in the characteristic time interval, the temperature of the thermal instability onset associated with the content of the volatile impurity. The approach proposed by the authors is aimed at increasing the lifetime of the oil and preventing unpredictable failures of the operating equipment.

  13. Method for generating all uniform π -pulse sequences used in deterministic dynamical decoupling

    NASA Astrophysics Data System (ADS)

    Qi, Haoyu; Dowling, Jonathan P.

    2015-09-01

    Dynamical decoupling has been actively investigated since Viola first suggested using a pulse sequence to protect a qubit from decoherence. Since then, many schemes of dynamical decoupling have been proposed to achieve high-order suppression, both analytically and numerically. However, hitherto, there has not been a systematic framework to understand all existing uniform π -pulse dynamical decoupling schemes. In this report, we use the projection pulse sequences as basic building blocks and concatenation as a way to combine them. We derived a concatenated-projection dynamical decoupling, a framework in which we can systematically construct pulse sequences to achieve arbitrary high suppression order. All previously known uniform dynamical decoupling sequences using π pulse can be fit into this framework. Understanding uniform dynamical decoupling as successive projections on the Hamiltonian will also give insights on how to invent new ways to construct better pulse sequences.

  14. Improvement of the identification of multiwall carbon nanotubes carpet thermal conductivity by pulsed photothermal method

    SciTech Connect

    Amin-Chalhoub, E.; Wattieaux, G.; Semmar, N.; Gaillard, M.; Petit, A.; Leborgne, C.

    2012-11-01

    Thermal properties in multiwall carbon nanotubes carpets and micro-devices are investigated using a nanosecond photothermal method. Gradually, the identification model and experimental protocol are performed to increase the method accuracy for the thermal conductivity determination. In the experimental protocol, a nanosecond UV monopulse laser beam is used to heat the surface of a multilayer (600 nm of Ti/20 {mu}m of carbon nanotube carpet) sample. In the 1D identification model with two layers and a thermal contact resistance, the effect of the laser excitation temporal shape is taken into account. In this study, this first approach allows to improve the accuracy of apparent thermal conductivity measurements of multiwall carbon nanotubes carpet. The carbon nanotubes carpet apparent thermal conductivity value went from being to 180 {+-} 5 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}. In the second approach, two laser beams are coupled in order to increase the interaction time duration from 27 ns to 60 ns. It becomes possible to probe different depths in the carpet. The obtained value (180 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}) confirms the pulsed photothermal method consistency for porous samples. Finally, assuming that the carbon nanotubes are parallel and without any defects, the equivalent intrinsic thermal conductivity of a single carbon nanotube is estimated to be around 3600 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}.

  15. A harmonic pulse testing method for leakage detection in deep subsurface storage formations

    NASA Astrophysics Data System (ADS)

    Sun, Alexander Y.; Lu, Jiemin; Hovorka, Susan

    2015-06-01

    Detection of leakage in deep geologic storage formations (e.g., carbon sequestration sites) is a challenging problem. This study investigates an easy-to-implement frequency domain leakage detection technology based on harmonic pulse testing (HPT). Unlike conventional constant-rate pressure interference tests, HPT stimulates a reservoir using periodic injection rates. The fundamental principle underlying HPT-based leakage detection is that leakage modifies a storage system's frequency response function, thus providing clues of system malfunction. During operations, routine HPTs can be conducted at multiple pulsing frequencies to obtain experimental frequency response functions, using which the possible time-lapse changes are examined. In this work, a set of analytical frequency response solutions is derived for predicting system responses with and without leaks for single-phase flow systems. Sensitivity studies show that HPT can effectively reveal the presence of leaks. A search procedure is then prescribed for locating the actual leaks using amplitude and phase information obtained from HPT, and the resulting optimization problem is solved using the genetic algorithm. For multiphase flows, the applicability of HPT-based leakage detection procedure is exemplified numerically using a carbon sequestration problem. Results show that the detection procedure is applicable if the average reservoir conditions in the testing zone stay relatively constant during the tests, which is a working assumption under many other interpretation methods for pressure interference tests. HPT is a cost-effective tool that only requires periodic modification of the nominal injection rate. Thus it can be incorporated into existing monitoring plans with little additional investment.

  16. A new method for evaluating the degeneration of articular cartilage using pulse-echo ultrasound

    NASA Astrophysics Data System (ADS)

    Sun, Anyu; Bai, Xiaolong; Ju, Bing-Feng

    2015-03-01

    This paper presents a novel nondestructive ultrasonic technique for measuring the sound speed and acoustic impedance of articular cartilage using the pulsed V(z,t) technique. V(z,t) data include a series of pulsed ultrasonic echoes collected using different distances between the ultrasonic transducer and the specimen. The 2D Fourier transform is applied to the V(z,t) data to reconstruct the 2D reflection spectrum R(θ,ω). To obtain the reflection coefficient of articular cartilage, the V(z,t) data from a reference specimen with a well-known reflection coefficient are obtained to eliminate the dependence on the general system transfer function. The ultrasound-derived aggregate modulus (Ha) is computed based on the measured reflection coefficient and the sound speed. In the experiment, 32 cartilage-bone samples were prepared from bovine articular cartilage, and 16 samples were digested using 0.25% trypsin solution. The sound speed and Ha of these cartilage samples were evaluated before and after degeneration. The magnitude of the sound speed decreased with trypsin digestion (from 1663 ± 5.6 m/s to 1613 ± 5.3 m/s). Moreover, the Young's modulus in the corresponding degenerative state was measured and was correlated with the ultrasound-derived aggregate modulus. The ultrasound-derived aggregate modulus was determined to be highly correlated with the Young's modulus (n = 16, r>0.895, p<0.003, Pearson correlation test for each measurement). The results demonstrate the effectiveness of using the proposed method to assess the changes in sound speed and the ultrasound-derived aggregate modulus of cartilage after degeneration.

  17. A novel method for active fissile mass estimation with a pulsed neutron source

    NASA Astrophysics Data System (ADS)

    Dubi, C.; Ridnik, T.; Israelashvili, I.; Pedersen, B.

    2013-07-01

    Neutron interrogation facilities for mass evaluation of Special Nuclear Materials (SNM) samples are divided into two main categories: passive interrogation, where all neutron detections are due to spontaneous events, and active interrogation, where fissions are induced on the tested material by an external neutron source. While active methods are, in general, faster and more effective, their analysis is much harder to carry out. In the paper, we will introduce a new formalism for analyzing the detection signal generated by a pulsed source active interrogation facility. The analysis is aimed to distinct between fission neutrons from the main neutron source in the system, and the surrounding "neutron noise". In particular, we derive analytic expressions for the first three central moments of the number of detections in a given time interval, in terms of the different neutron sources. While the method depends on exactly the same physical assumptions as known models, the simplicity of the suggested formalism allows us to take into account the variance of the external neutron source—an effect that was so far neglected.

  18. Fixed and pulsed gradient diffusion methods in low-field core analysis.

    PubMed

    Leu, Gabriela; Fordham, Edmund J; Hürlimann, Martin D; Frulla, Phil

    2005-02-01

    We review diffusion-weighted relaxation protocols for two-dimensional diffusion/relaxation time (D, T(2)) distributions and their application to fluid-saturated sedimentary rocks at low fields typical of oil-well logging tools (< or = 2 MHz for 1H). Fixed field gradient (FFG) protocols may be implemented in logging tools and in the laboratory; there, pulsed field gradient (PFG) protocols are also available. In either category, direct or stimulated echoes may be used for the diffusion evolution periods. We compare the results of several variant FFG and PFG protocols obtained on liquids and two contrasting sedimentary rocks. For liquids and rocks of negligible internal gradients (g(int)), results are comparable, as expected, for all the studied protocols. For rocks of strong g(int), protocol-dependent artifacts are seen in the joint (D, T2) distributions, consistent with the effects of the internal fields. For laboratory petrophysics, the PFG methods offer several advantages: (a) significantly improved signal-to-noise ratio and acquisition times for repetitions over many samples; (b) freedom from heteronuclear contamination when fluorinated liquids are used in core holders; and (c) a palette of variants--one comparable with the FFG--for the study of rocks of significant g(int). Given suitable hardware, both PFG and FFG methods can be implemented in the same bench-top apparatus, providing a versatile test bed for application in a petrophysical laboratory. PMID:15833632

  19. Lattice Boltzmann method for short-pulsed laser transport in a multi-layered medium

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Yi, Hong-Liang; Tan, He-Ping

    2015-04-01

    We construct a lattice Boltzmann method (LBM) for transient radiative transfer in one-dimensional multi-layered medium with distinct refractive index in each layer. The left boundary is irradiated normally by a short-pulsed laser. The Fresnel interfaces conditions, which incorporate reflection and refraction, are used at the boundaries and the interfaces. Based on the Fresnel's law and Snell's law, the interfacial intensity formulas are introduced. The collimated and diffuse intensities are treated individually. At a transient time step, the collimated component is first solved by LBM and then embedded into the transient radiative transfer equation as a source term. To keep the consistency of the directions in all the layers, angular interpolation of the intensities at the interfaces is adopted. The transient radiative transfer in a two-layer medium is first investigated, and the time-resolved results are validated by comparing with those by the Monte Carlo method (MCM). Of particular interest, the angular intensities along the slab at different times are presented to illustrate a variety of interesting phenomena, and the discontinuous nature of the intensity at the interfaces is discussed. The effects of various parameters on the time-resolved signals are examined.

  20. Method specificity of non-invasive blood pressure measurement: oscillometry and finger pulse pressure vs acoustic methods.

    PubMed

    De Mey, C; Schroeter, V; Butzer, R; Roll, S; Belz, G G

    1995-10-01

    1. The agreement of blood pressure measurements by stethoscope auscultation (SBPa, DBPa-IV and DBPa-V), oscillometry (Dinamap; SBPo, and DBPo) and digital photoplethysmography (Finapres; SBPf, and DBPf) with the graphical analysis of the analogue microphone signals of vascular wall motion sound (SBPg and DBPg) was evaluated in eight healthy subjects in the presence of responses to the intravenous infusion of 1 microgram min-1 isoprenaline. 2. In general, there was good agreement between the SBP/DBP-measurements based on auscultatory Korotkoff-I- and IV-criteria and the reference method; the average method difference in estimating the isoprenaline responses for SBPa-SBPg was: -1.1, 95% CI: -5.4 to 3.1 mm Hg with a within-subject between-method repeatability coefficient (REP) of 11.6 mm Hg and for DBPa-IV-DBPg: 3.5, 95% CI: -0.5 to 6.5 mm Hg, REP: 11.5 mm Hg. The ausculatation of Korotkoff-V substantially overestimated the isoprenaline induced reduction of DBP: method difference DBPa-V-DBPg: -11.3, 95% CI: -17.8 to -4.7 mm Hg, REP: 31.8 mm Hg. 3. Oscillometry yielded good approximations for the SBP response to isoprenaline (average method difference SBPo-SBPg: -2.9, 95% CI: -9.0 to 3.3 mm Hg, REP: 17.6 mm Hg) but was poorly sensitive with regard to the DBP responses: method difference DBPo-DBPg: 6.5, 95% CI: -1.3 to 14.3 mm Hg, REP: 25.7 mm Hg. 4. Whilst the finger pulse pressure agreed well with regard to DBP (method difference for the DBP responses to isoprenaline: DBPf-DBPg: 1.8, 95% CI: -5.1 to 8.6 mm Hg, REP: 18.5 mm Hg) it was rather unsatisfactory with regard to SBP (method difference SBPf-SBPg: -14.1, 95% CI: -28.2 to -0.1 mm Hg, REP: 49.9 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8554929

  1. The mechanism of radiolysis of alkaline-earth nitrates

    NASA Astrophysics Data System (ADS)

    Anan'ev, V.; Kriger, L.; Miklin, M.

    2015-04-01

    The formation of peroxynitrite and nitrite in crystalline alkaline-earth nitrates under γ-irradiation at 310 K by optical reflectance spectroscopy has been studied. The radiolysis of Sr(NO3)2 and Ba(NO3)2 results in nitrite and peroxynitrite, Mg(NO3)2·6H2O and Ca(NO3)2·4H2O - nitrite. The mechanism for nitrite and peroxynitrite formation under γ-irradiation of crystalline alkaline-earth nitrates has been discussed.

  2. Decomposition of PCBs in oils using gamma radiolysis

    SciTech Connect

    Mincher, B.J.; Arbon, R.E.; Schwendiman, G.L.

    1996-12-31

    This paper investigates the radiolysis of the polychlorinated biphenyls (PCBs) in several oil matrices. The results of mechanism and kinetic studies in isooctane are presented. The decomposition of PCBs in isooctane is shown to occur by reductive dechlorination due to electron capture and to proceed with pseudo-first-order kinetics. The rate is dependent on the initial PCB concentration. Electron capture detection gas chromatograms confirm that dechlorination also occurs with commercial Aroclor PCBs in irradiated transformer and hydraulic oils. The results of a demonstration experiment involving PCB contaminated waste hydraulic oils are presented.

  3. Breast mass segmentation in digital mammography based on pulse coupled neural network and level set method

    NASA Astrophysics Data System (ADS)

    Xie, Weiying; Ma, Yide; Li, Yunsong

    2015-05-01

    A novel approach to mammographic image segmentation, termed as PCNN-based level set algorithm, is presented in this paper. Just as its name implies, a method based on pulse coupled neural network (PCNN) in conjunction with the variational level set method for medical image segmentation. To date, little work has been done on detecting the initial zero level set contours based on PCNN algorithm for latterly level set evolution. When all the pixels of the input image are fired by PCNN, the small pixel value will be a much more refined segmentation. In mammographic image, the breast tumor presents big pixel value. Additionally, the mammographic image with predominantly dark region, so that we firstly obtain the negative of mammographic image with predominantly dark region except the breast tumor before all the pixels of an input image are fired by PCNN. Therefore, in here, PCNN algorithm is employed to achieve mammary-specific, initial mass contour detection. After that, the initial contours are all extracted. We define the extracted contours as the initial zero level set contours for automatic mass segmentation by variational level set in mammographic image analysis. What's more, a new proposed algorithm improves external energy of variational level set method in terms of mammographic images in low contrast. In accordance with the gray scale of mass region in mammographic image is higher than the region surrounded, so the Laplace operator is used to modify external energy, which could make the bright spot becoming much brighter than the surrounded pixels in the image. A preliminary evaluation of the proposed method performs on a known public database namely MIAS, rather than synthetic images. The experimental results demonstrate that our proposed approach can potentially obtain better masses detection results in terms of sensitivity and specificity. Ultimately, this algorithm could lead to increase both sensitivity and specificity of the physicians' interpretation of

  4. Phase transformations in nanostructured coatings based on Zr-Y-O and produced by a pulse magnetron sputtering method

    SciTech Connect

    Fedorischeva, Marina V. Kalashnikov, Mark P. Sergeev, Victor P.

    2015-10-27

    Deposition of nanostructured coatings on the basis of Zr-Y-O was implemented by the pulse magnetron methods. Structural-phase states and morphology of the nanostructured coatings were investigated by TEM, SEM and the high-temperature X-ray method. The method of the high-temperature X-ray diffraction revealed the presence of reversible phase transition of the tetragonal phase to the monoclinic phase, which can ensure stress relaxation and closure of surface cracks.

  5. Coupling the Mixed Potential and Radiolysis Models for Used Fuel Degradation

    SciTech Connect

    Buck, Edgar C.; Jerden, James L.; Ebert, William L.; Wittman, Richard S.

    2013-08-30

    The primary purpose of this report is to describe the strategy for coupling three process level models to produce an integrated Used Fuel Degradation Model (FDM). The FDM, which is based on fundamental chemical and physical principals, provides direct calculation of radionuclide source terms for use in repository performance assessments. The G-value for H2O2 production (Gcond) to be used in the Mixed Potential Model (MPM) (H2O2 is the only radiolytic product presently included but others will be added as appropriate) needs to account for intermediate spur reactions. The effects of these intermediate reactions on [H2O2] are accounted for in the Radiolysis Model (RM). This report details methods for applying RM calculations that encompass the effects of these fast interactions on [H2O2] as the solution composition evolves during successive MPM iterations and then represent the steady-state [H2O2] in terms of an “effective instantaneous or conditional” generation value (Gcond). It is anticipated that the value of Gcond will change slowly as the reaction progresses through several iterations of the MPM as changes in the nature of fuel surface occur. The Gcond values will be calculated with the RM either after several iterations or when concentrations of key reactants reach threshold values determined from previous sensitivity runs. Sensitivity runs with RM indicate significant changes in G-value can occur over narrow composition ranges. The objective of the mixed potential model (MPM) is to calculate the used fuel degradation rates for a wide range of disposal environments to provide the source term radionuclide release rates for generic repository concepts. The fuel degradation rate is calculated for chemical and oxidative dissolution mechanisms using mixed potential theory to account for all relevant redox reactions at the fuel surface, including those involving oxidants produced by solution radiolysis and provided by the radiolysis model (RM). The RM calculates

  6. Phase retrieval and time-frequency methods in the measurement of ultrashort laser pulses

    SciTech Connect

    DeLong, K.W.; Fittinghoff, D.N.; Ladera, C.L.; Trebino, R.

    1995-02-01

    Recently several techniques have become available to measure the time- (or frequency-) dependent intensity and phase of ultrashort laser pulses. One of these, Frequency-Resolved Optical Gating (FROG), is rigorous and has achieved single-laser-shot operation. FROG combines the concepts of time-frequency analysis in the form of spectrogram generation (in order to create a two-dimensional problem), and uses a phase-retrieval-based algorithm to invert the experimental data to yield the intensity and phase of the laboratory laser pulse. In FROG it is easy to generate a spectrogram of the unknown signal, and inversion of the spectrogram to recover the signal is the main goal. Because the temporal width of a femtosecond laser pulse is much shorter than anything achievable by electronics, FROG uses the pulse to measure itself. In FROG, the laser pulse is split into two replicas of itself by a partially reflecting beamsplitter, and the two replicas interact with each other in a medium with an instantaneous nonlinear-optical response. This interaction generates a signal field that is then frequency-resolved using a spectrometer. The spectrum of the signal field is measured for all relevant values of the temporal delay between the two pulses. Here, the authors employ FROG and FROG related techniques to measure the time-dependent intensity and phase of an ultrashort laser pulse.

  7. Non-contact thrust stand calibration method for repetitively pulsed electric thrusters.

    PubMed

    Wong, Andrea R; Toftul, Alexandra; Polzin, Kurt A; Pearson, J Boise

    2012-02-01

    A thrust stand calibration technique for use in testing repetitively pulsed electric thrusters for in-space propulsion has been developed and tested using a modified hanging pendulum thrust stand. In the implementation of this technique, current pulses are applied to a solenoid to produce a pulsed magnetic field that acts against a permanent magnet mounted to the thrust stand pendulum arm. The force on the magnet is applied in this non-contact manner, with the entire pulsed force transferred to the pendulum arm through a piezoelectric force transducer to provide a time-accurate force measurement. Modeling of the pendulum arm dynamics reveals that after an initial transient in thrust stand motion the quasi-steady average deflection of the thrust stand arm away from the unforced or "zero" position can be related to the average applied force through a simple linear Hooke's law relationship. Modeling demonstrates that this technique is universally applicable except when the pulsing period is increased to the point where it approaches the period of natural thrust stand motion. Calibration data were obtained using a modified hanging pendulum thrust stand previously used for steady-state thrust measurements. Data were obtained for varying impulse bit at constant pulse frequency and for varying pulse frequency. The two data sets exhibit excellent quantitative agreement with each other. The overall error on the linear regression fit used to determine the calibration coefficient was roughly 1%. PMID:22380121

  8. Multi-wave ultrasonic Doppler method for measuring high flow-rates using staggered pulse intervals

    NASA Astrophysics Data System (ADS)

    Muramatsu, Ei; Murakawa, Hideki; Sugimoto, Katsumi; Asano, Hitoshi; Takenaka, Nobuyuki; Furuichi, Noriyuki

    2016-02-01

    The ultrasonic pulsed Doppler method (UDM) can obtain a velocity profile along the path of an ultrasonic beam. However, the UDM measurement volume is relatively large and it is known that the measurement volume affects the measurement accuracy. In this study, the effect of the measurement volume on velocity and flow rate measurements is analytically and experimentally evaluated. The velocities measured using UDM are considered to be ensemble-averaged values over the measurement volume in order to analyze the velocity error due to the measurement volume, while the flow rates are calculated from the integration of the velocity profile across the pipe. The analytical results show that the channel width, i.e. the spatial resolution along the ultrasonic beam axis, rather than the ultrasonic beam diameter, strongly influences the flow rate measurement. To improve the accuracy of the flow rate, a novel method using a multi-wave ultrasonic transducer consisting of two piezo-electric elements with different basic frequencies is proposed to minimize the size of the measurement volume in the near-wall region of a pipe flow. The velocity profiles in the near-wall region are measured using an 8 MHz sensor with a small diameter, while those far from the transducer are measured using a hollow 2 MHz sensor in the multi-wave transducer. The applicability of the multi-wave transducer was experimentally investigated using the water flow-rate calibration facility at the National Institute of Advanced Industrial Science and Technology (AIST). As a result, the errors in the flow rate were found to be below  -1%, while the multi-wave method is shown to be particularly effective for measuring higher flow rates in a large-diameter pipe.

  9. Application of the Hartmann method in the investigation of the profile of wavefronts of high-power pulsed lasers

    SciTech Connect

    L`vov, L.V.; Merkulov, S.G.; Ozerov, M.A.

    1994-11-01

    The Hartmann method was used in an investigation of the wavefront profile of the infrared radiation emitted by high-power pulsed lasers. The wavefront profiles were studied for the iodine lasers used in the ISKRA-4 and ISKRA-5 facilities. 5 refs., 3 figs.

  10. A hybrid body technique: does the pulse diagnostic cun guan chi method have Chinese-Tibetan origins?

    PubMed

    Hsu, Elisabeth

    2008-01-01

    This article investigates the medieval origins of the main pulse diagnostic method in contemporary Chinese medicine, sometimes known as san bu (three sectors) method, which requires physicians to examine the mai (vessels, vessel movements or pulse) on the wrist at the three locations cun guan chi (inch, gate, foot). The article provides evidence to suggest that this body technique grew out of an earlier Chinese one, the cun chi (inch-foot) method, which appears to have aimed at investigating the qualities of yin and yang in order to determine the condition of a patient by means of exploring fairly large areas of the patient's body surface with the palms. The article furthermore posits that the cun chi method was decisively transformed in medieval times, presumably due to the impact of early Tibetan pulse diagnostic practices: it became framed in a numerology of three and started advocating the use of the fingertips for sensing the pulse beats. The article, which draws on detailed textual analyses of medieval manuscripts, on visual evidence and also on psychophysical research, furthermore highlights how misunderstandings can constructively contribute to cultural communication. PMID:18828567

  11. Methods of Optimal Control of Laser-Plasma Instabilities Using Spike Trains of Uneven Duration and Delay (STUD Pulses)

    NASA Astrophysics Data System (ADS)

    Afeyan, Bedros

    2013-10-01

    We have recently introduced and extensively studied a new adaptive method of LPI control. It promises to extend the effectiveness of laser as inertial fusion drivers by allowing active control of stimulated Raman and Brillouin scattering and crossed beam energy transfer. It breaks multi-nanosecond pulses into a series of picosecond (ps) time scale spikes with comparable gaps in between. The height and width of each spike as well as their separations are optimization parameters. In addition, the spatial speckle patterns are changed after a number of successive spikes as needed (from every spike to never). The combination of these parameters allows the taming of parametric instabilities to conform to any desired reduced reflectivity profile, within the bounds of the performance limitations of the lasers. Instead of pulse shaping on hydrodynamical time scales, far faster (from 1 ps to 10 ps) modulations of the laser profile will be needed to implement the STUD pulse program for full LPI control. We will show theoretical and computational evidence for the effectiveness of the STUD pulse program to control LPI. The physics of why STUD pulses work and how optimization can be implemented efficiently using statistical nonlinear optical models and techniques will be explained. We will also discuss a novel diagnostic system employing STUD pulses that will allow the boosted measurement of velocity distribution function slopes on a ps time scale in the small crossing volume of a pump and a probe beam. Various regimes from weak to strong coupling and weak to strong damping will be treated. Novel pulse modulation schemes and diagnostic tools based on time-lenses used in both microscope and telescope modes will be suggested for the execution of the STUD pule program. Work Supported by the DOE NNSA-OFES Joint Program on HEDLP and DOE OFES SBIR Phase I Grants.

  12. Method and apparatus for fine tuning an orifice pulse tube refrigerator

    DOEpatents

    Swift, Gregory W.; Wollan, John J.

    2003-12-23

    An orifice pulse tube refrigerator uses flow resistance, compliance, and inertance components connected to a pulse tube for establishing a phase relationship between oscillating pressure and oscillating velocity in the pulse tube. A temperature regulating system heats or cools a working gas in at least one of the flow resistance and inertance components. A temperature control system is connected to the temperature regulating system for controlling the temperature of the working gas in the at least one of the flow resistance and inertance components and maintains a control temperature that is indicative of a desired temporal phase relationship.

  13. An automatic method for arterial pulse waveform recognition using KNN and SVM classifiers.

    PubMed

    Pereira, Tânia; Paiva, Joana S; Correia, Carlos; Cardoso, João

    2016-07-01

    The measurement and analysis of the arterial pulse waveform (APW) are the means for cardiovascular risk assessment. Optical sensors represent an attractive instrumental solution to APW assessment due to their truly non-contact nature that makes the measurement of the skin surface displacement possible, especially at the carotid artery site. In this work, an automatic method to extract and classify the acquired data of APW signals and noise segments was proposed. Two classifiers were implemented: k-nearest neighbours and support vector machine (SVM), and a comparative study was made, considering widely used performance metrics. This work represents a wide study in feature creation for APW. A pool of 37 features was extracted and split in different subsets: amplitude features, time domain statistics, wavelet features, cross-correlation features and frequency domain statistics. The support vector machine recursive feature elimination was implemented for feature selection in order to identify the most relevant feature. The best result (0.952 accuracy) in discrimination between signals and noise was obtained for the SVM classifier with an optimal feature subset . PMID:26403299

  14. Designing Pulse Laser Surface Modification of H13 Steel Using Response Surface Method

    NASA Astrophysics Data System (ADS)

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2011-01-01

    This paper presents a design of experiment (DOE) for laser surface modification process of AISI H13 tool steel in achieving the maximum hardness and minimum surface roughness at a range of modified layer depth. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). The response surface method with Box-Behnken design approach in Design Expert 7 software was used to design the H13 laser surface modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified surface roughness was measured using two-dimensional surface profilometer. The correlation of the three laser processing parameters and the modified surface properties was specified by plotting three-dimensional graph. The hardness properties were tested at 981 mN force. From metallographic study, the laser modified surface depth was between 37 μm and 150 μm. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 μm. The maximum hardness achieved was between 728 and 905 HV0.1. These findings are significant to modern development of hard coatings for wear resistant applications.

  15. Pulsed photothermal radiometry as a method for investigating blood vessel-like structures.

    PubMed

    Schmitz, C H; Oberheide, U; Lohmann, S; Lubatschowski, H; Ertmer, W

    2001-04-01

    Pulsed photothermal radiometry (PPTR) is known to be suitable for in vivo investigations of tissue optical properties. As a noncontact, nondestructive method it is a very attractive candidate for on-line dosimetry of laser treatments that rely on thermal laser-tissue interaction. In this article, we extend the one-dimensional (1D) analytical formalism that has widely been used to describe PPTR signals to a two-dimensional treatment of a simplified model of a blood vessel. This approach leads to quantitative description of a PPTR signal that, unlike in an 1D treatment, not only shows changes in time, but also varies in space. Using this approach, we are able to gain instructive understanding on how target characteristics of a blood vessel-like structure influence such a spatiotemporal PPTR signal. Likewise, the ability of extracting target features from those measurements is evaluated. Subsequently, we present experimental realization of the idealized model of a blood vessel as used in our theory. Comparison of actual PPTR measurements with theoretical predictions allow vessel localization laterally and in depth. Using our setup, we furthermore demonstrate the influence of flow inside the vessel on the measured signal. PMID:11375732

  16. Determination of lithium sulphur batteries internal resistance by the pulsed method during galvanostatic cycling

    NASA Astrophysics Data System (ADS)

    Kolosnitsyn, V. S.; Kuzmina, E. V.; Mochalov, S. E.

    2014-04-01

    The pulsed method of measuring impedance is described. The cell is galvanostatically stimulated by a bipolar current signal of square shape. The cell response is registered by sampling U+[i], U-[i] with selected period Δt. The impedance spectra are calculated by direct Fourier transform. The internal resistance of the lithium sulphur cell is characteristically minimum in the calculated impedance diagrams in the frequency range of 0.035-5 Hz. It is shown that the lithium sulphur cells have maximum internal resistance at the transient between high and low voltage plateaus of charge and discharge curves. The internal resistance increases significantly during the initial stages of cycling because of the formation of passivation layers at the electrodes. It was found that the internal resistance of the lithium sulphur cell in the same charge state is governed by the way in which it is achieved. This is explained by differences in molar volumes of products generated in the sulphur electrode by electrochemical reaction during charging and discharging.

  17. Energetic pulses in exciton-phonon molecular chains and conservative numerical methods for quasilinear Hamiltonian systems.

    PubMed

    Lemesurier, Brenton

    2013-09-01

    The phenomenon of coherent energetic pulse propagation in exciton-phonon molecular chains such as α-helix protein is studied using an ODE system model of Davydov-Scott type, both with numerical studies using a new unconditionally stable fourth-order accurate energy-momentum conserving time discretization and with analytical explanation of the main numerical observations. Impulsive initial data associated with initial excitation of a single amide-I vibration by the energy released by ATP hydrolysis are used as well as the best current estimates of physical parameter values. In contrast to previous studies based on a proposed long-wave approximation by the nonlinear Schrödinger (NLS) equation and focusing on initial data resembling the soliton solutions of that equation, the results here instead lead to approximation by the third derivative nonlinear Schrödinger equation, giving a far better fit to observed behavior. A good part of the behavior is indeed explained well by the linear part of that equation, the Airy PDE, while other significant features do not fit any PDE approximation but are instead explained well by a linearized analysis of the ODE system. A convenient method is described for construction of the highly stable, accurate conservative time discretizations used, with proof of its desirable properties for a large class of Hamiltonian systems, including a variety of molecular models. PMID:24125294

  18. Designing Pulse Laser Surface Modification of H13 Steel Using Response Surface Method

    SciTech Connect

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2011-01-17

    This paper presents a design of experiment (DOE) for laser surface modification process of AISI H13 tool steel in achieving the maximum hardness and minimum surface roughness at a range of modified layer depth. A Rofin DC-015 diffusion-cooled CO{sub 2} slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). The response surface method with Box-Behnken design approach in Design Expert 7 software was used to design the H13 laser surface modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified surface roughness was measured using two-dimensional surface profilometer. The correlation of the three laser processing parameters and the modified surface properties was specified by plotting three-dimensional graph. The hardness properties were tested at 981 mN force. From metallographic study, the laser modified surface depth was between 37 {mu}m and 150 {mu}m. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 {mu}m. The maximum hardness achieved was between 728 and 905 HV{sub 0.1}. These findings are significant to modern development of hard coatings for wear resistant applications.

  19. Pr–Fe–B+α-Fe nanocomposite film magnets prepared by pulsed laser deposition method

    NASA Astrophysics Data System (ADS)

    Yamashita, Akihiro; Nakano, Masaki; Oshima, Shuichi; Yanai, Takeshi; Fukunaga, Hirotoshi

    2016-07-01

    An increase in the remanence of an isotropic film magnet is indispensable to improve the properties of miniaturized devices. We, therefore, tried to prepare Pr–Fe–B/α-Fe multilayered nanocomposite thick-film magnets by a pulsed laser deposition (PLD) method. Namely, a rotated target composed of a Pr x Fe14B (x = 2.2 or 2.4) target together with an α-Fe segment was ablated. We also took account of a small spot size of the laser beam in order to suppress the emission of droplets (large particles) from each target. An optimization on the area of the α-Fe segment in each Pr x Fe14B target was carried out, and the remanence of an annealed film reached approximately 1.1 T. Moreover, a transmission electron microscopy (TEM) observation of the above-mentioned sample revealed that the microstructure varied from a multilayered structure (as-deposited) to a dispersed one through the annealing process. Resultantly, the annealed film had a dispersed nanocomposite structure with good exchange coupling.

  20. [Calculation and analysis of arc temperature field of pulsed TIG welding based on Fowler-Milne method].

    PubMed

    Xiao, Xiao; Hua, Xue-Ming; Wu, Yi-Xiong; Li, Fang

    2012-09-01

    Pulsed TIG welding is widely used in industry due to its superior properties, and the measurement of arc temperature is important to analysis of welding process. The relationship between particle densities of Ar and temperature was calculated based on the theory of spectrum, the relationship between emission coefficient of spectra line at 794.8 nm and temperature was calculated, arc image of spectra line at 794.8 nm was captured by high speed camera, and both the Abel inversion and Fowler-Milne method were used to calculate the temperature distribution of pulsed TIG welding. PMID:23240389

  1. Quantum interference in laser-assisted photoionization and analytical methods for the measurement of an attosecond xuv pulse

    SciTech Connect

    Ge Yucheng; He Haiping

    2011-08-15

    Investigations of the quantum interference in laser-assisted photoionization by an attosecond extreme ultraviolet (xuv) pulse shows an approximately constant value for the total photoionizations for different laser intensities. The square of the full width at half maximum of a photoelectron energy spectrum (PES) linearly depends on the laser intensity. By determining the laser-related phase of each streaked electron and using a transfer equation with linear corrections, an analytically quick method is proposed for precisely reconstructing the xuv pulse intensity (chirp) from one (two) measured PES(s) with a theoretical root-mean-square temporal (energy) difference of less than 1 attosecond (0.1 eV).

  2. Method of production H/sub 2/ using a rotating drum reactor with a pulse jet heat source

    DOEpatents

    Paulson, L.E.

    1988-05-13

    A method of producing hydrogen by an endothermic steam-carbon reaction using a rotating drum reactor and a pulse jet combustor. The pulse jet combustor uses coal dust as a fuel to provide reaction temperatures of 1300/degree/ to 1400/degree/F. Low-rank coal, water, limestone and catalyst are fed into the drum reactor where they are heated, tumbled and reacted. Part of the reaction product from the rotating drum reactor is hydrogen which can be utilized in suitable devices. 1 fig.

  3. All solid-state spectral broadening: an average and peak power scalable method for compression of ultrashort pulses.

    PubMed

    Seidel, Marcus; Arisholm, Gunnar; Brons, Jonathan; Pervak, Vladimir; Pronin, Oleg

    2016-05-01

    Spectral broadening in bulk material is a simple, robust and low-cost method to extend the bandwidth of a laser source. Consequently, it enables ultrashort pulse compression. Experiments with a 38 MHz repetition rate, 50 W average power Kerr-lens mode-locked thin-disk oscillator were performed. The initially 1.2 μJ, 250 fs pulses are compressed to 43 fs by means of self-phase modulation in a single 15 mm thick quartz crystal and subsequent chirped-mirror compression. The losses due to spatial nonlinear effects are only about 40 %. A second broadening stage reduced the Fourier transform limit to 15 fs. It is shown that the intensity noise of the oscillator is preserved independent of the broadening factor. Simulations manifest the peak power scalability of the concept and show that it is applicable to a wide range of input pulse durations and energies. PMID:27137557

  4. Radiolysis Model Formulation for Integration with the Mixed Potential Model

    SciTech Connect

    Buck, Edgar C.; Wittman, Richard S.

    2014-07-10

    The U.S. Department of Energy Office of Nuclear Energy (DOE-NE), Office of Fuel Cycle Technology has established the Used Fuel Disposition Campaign (UFDC) to conduct the research and development activities related to storage, transportation, and disposal of used nuclear fuel (UNF) and high-level radioactive waste. Within the UFDC, the components for a general system model of the degradation and subsequent transport of UNF is being developed to analyze the performance of disposal options [Sassani et al., 2012]. Two model components of the near-field part of the problem are the ANL Mixed Potential Model and the PNNL Radiolysis Model. This report is in response to the desire to integrate the two models as outlined in [Buck, E.C, J.L. Jerden, W.L. Ebert, R.S. Wittman, (2013) “Coupling the Mixed Potential and Radiolysis Models for Used Fuel Degradation,” FCRD-UFD-2013-000290, M3FT-PN0806058

  5. Oxygen effect in the radiolysis of proteins. III. Haemoglobin.

    PubMed

    Puchała, M; Schuessler, H

    1993-08-01

    Radiolysis of haemoglobin was carried out in phosphate buffer under air, N2 or N2O and with and without ethanol. Radiation products were separated by SDS-PAGE. The loss of subunits and simultaneous aggregation and fragmentation of haemoglobin was measured, if OH-radicals were unscavenged. There was no sensitizing effect of oxygen on the degradation process. Radiation-induced fragmentation was not a random process, but produced specific fragments. The estimated molecular weights of these fragments gave further support to the assumption that the aminoacyl-proline peptide group is the preferential breaking site if OH radicals react with proteins in the presence of oxygen. In contrast with lactate dehydrogenase and bovine serum albumin such fragmentation was observed not only after aerobic radiolysis but also under anaerobic conditions. This difference must be caused by the Feporphyrin system which reacts with H2O2 under release of oxygen. If haemoglobin was irradiated under air the yield of aggregates was much lower than under N2O or N2. PMID:8103537

  6. Method and means for generating a synchronizing pulse from a repetitive wave of varying frequency

    DOEpatents

    DeVolpi, Alexander; Pecina, Ronald J.; Travis, Dale J.

    1976-01-01

    An event that occurs repetitively at continuously changing frequencies can be used to generate a triggering pulse which is used to synchronize or control. The triggering pulse is generated at a predetermined percentage of the period of the repetitive waveform without regard to frequency. Counts are accumulated in two counters, the first counting during the "on" fraction of the period, and the second counting during the "off" fraction. The counts accumulated during each cycle are compared. On equality the trigger pulse is generated. Count input rates to each counter are determined by the ratio of the on-off fractions of the event waveform and the desired phase relationship. This invention is of particular utility in providing a trigger or synchronizing pulse during the open period of the shutter of a high-speed framing camera during its acceleration as well as its period of substantially constant speed.

  7. Radiolysis of aqueous solutions of ammonium bicarbonate over a large dose range

    NASA Astrophysics Data System (ADS)

    Draganić, Z. D.; Negrón-Mendoza, A.; Sehested, K.; Vujošević, S. I.; Navarro-Gonzáles, R.; Albarrán-Sanchez, M. G.; Draganić, I. G.

    Oxygen-free aqueous solutions of 0.05 mol dm -3 ammonium and sodium bicarbonate were studied after receiving various doses of 60Co gammas (0.01-400 kGy) or 0.5-20 Gy pulses of 10 Mev electrons. Formate and oxalate were found to be the main radiolytic products, in addition to trace amounts of formaldehyde and an unidentified polymer. A large initial yield of formate in the γ-radiolysis, G( HCOO-)=2.2, is due to the reaction COO - + HCO -3⤦HCOO -+CO -3. The efficiency of organic synthesis within the large dose range studied is low and is explained by efficient pathways leading to the reformation of bicarbonate, where the reaction COO -+CO -3 is particularly significant. Computer fitting of the data obtained gives k(COO - + HCO -3)=(2±0.4) x 10 3 dm 3 mol -1 s -1, k(COO -+CO -3) = (5±1) x 10 7 dm 3 mol -1 s -1, k(NH 2+HCO -3)< 10 4 dm 3 mol -1 s -1, and k(NH 2+CO -3) = (1.5±0.5) x 10 9 dm 3 mol -1 s -1.

  8. Solid cartridge for a pulse weld forming electrode and method of joining tubular members

    DOEpatents

    Bonnen, John Joseph Francis; Golovashchenko, Sergey Fedorovich; Mamutov, Alexander; Maison, Lloyd Douglas; Dawson, Scott Alwyn; deVries, James

    2016-02-23

    A cartridge assembly is disclosed for a pulse welding a first tube supported on a mandrel to a second tube. An outer tool is assembled over the second tube and a stored charge is discharged in the cartridge assembly. The cartridge comprises an annular conductor and a solid casing enveloping the conductor. The stored charge is electrically connected to the conductor and discharged through the conductor to compress the second tube and pulse weld the second tube to the first tube.

  9. Generalization of the time-dependent numerical renormalization group method to finite temperatures and general pulses

    NASA Astrophysics Data System (ADS)

    Nghiem, H. T. M.; Costi, T. A.

    2014-02-01

    evolved between the initial and final states via a sequence of small quantum quenches within a finite time interval instead of by a single large and instantaneous quantum quench. The formalism for this is provided, thus generalizing the TDNRG method to multiple quantum quenches, periodic switching, and general pulses. This formalism, like our finite-temperature generalization of the single-quench case, rests on no other approximation than the NRG approximation. The results are illustrated numerically by application to the Anderson impurity model.

  10. Method for Thermal Spraying of Coatings Using Resonant-Pulsed Combustion

    NASA Technical Reports Server (NTRS)

    Paxson, Daniel E.

    2008-01-01

    A method has been devised for high-volume, high-velocity surface deposition of protective metallic coatings on otherwise vulnerable surfaces. Thermal spraying is used whereby the material to be deposited is heated to the melting point by passing through a flame. Rather than the usual method of deposition from the jet formed from the combustion products, this innovation uses non-steady combustion (i.e. high-frequency, periodic, confined bursts), which generates not only higher temperatures and heat transfer rates, but exceedingly high impingement velocities an order of magnitude higher than conventional thermal systems. Higher impingement rates make for better adhesion. The high heat transfer rates developed here allow the deposition material to be introduced, not as an expensive powder with high surface-area-to-volume, but in convenient rod form, which is also easier and simpler to feed into the system. The nonsteady, resonant combustion process is self-aspirating and requires no external actuation or control and no high-pressure supply of fuel or air. The innovation has been demonstrated using a commercially available resonant combustor shown in the figure. Fuel is naturally aspirated from the tank through the lower Tygon tube and into the pulsejet. Air for starting is ported through the upper Tygon tube line. Once operation commences, this air is no longer needed as additional air is naturally aspirated through the inlet. A spark plug on the device is needed for starting, but the process carries on automatically as the operational device is resonant and reignites itself with each 220-Hz pulse.

  11. Method for generating all uniform π-pulse sequences used in deterministic dynamical decoupling

    NASA Astrophysics Data System (ADS)

    Qi, Haoyu; Dowling, Jonathan

    Dynamical decoupling has been actively investigated since Viola first suggested using a pulse sequence to protect a qubit from decoherence. Since then, many schemes of dynamical decoupling have been proposed to achieve high-order suppression, both analytically and numerically. However, hitherto, there has not been a systematic framework to understand all existing uniform π-pulse dynamical decoupling schemes. In this report, we use the projection pulse sequences as basic building blocks and concatenation as a way to combine them. We derived a concatenated-projection dynamical decoupling, a framework in which we can systematically construct pulse sequences to achieve arbitrary high suppression order. All previously known uniform dynamical decoupling sequences using π pulse can be fit into this framework. Understanding uniform dynamical decoupling as successive projections on the Hamiltonian will also give insights on how to invent new ways to construct better pulse sequences. This work is supported by AirForce Office of Scientific Research, the US Army Research Office, and the National Science Foundation.

  12. Non-Contact Thrust Stand Calibration Method for Repetitively-Pulsed Electric Thrusters

    NASA Technical Reports Server (NTRS)

    Wong, Andrea R.; Toftul, Alexandra; Polzin, Kurt A.; Pearson, J. Boise

    2011-01-01

    A thrust stand calibration technique for use in testing repetitively-pulsed electric thrusters for in-space propulsion has been developed and tested using a modified hanging pendulum thrust stand. In the implementation of this technique, current pulses are applied to a solenoidal coil to produce a pulsed magnetic field that acts against the magnetic field produced by a permanent magnet mounted to the thrust stand pendulum arm. The force on the magnet is applied in this non-contact manner, with the entire pulsed force transferred to the pendulum arm through a piezoelectric force transducer to provide a time-accurate force measurement. Modeling of the pendulum arm dynamics reveals that after an initial transient in thrust stand motion the quasisteady average deflection of the thrust stand arm away from the unforced or zero position can be related to the average applied force through a simple linear Hooke s law relationship. Modeling demonstrates that this technique is universally applicable except when the pulsing period is increased to the point where it approaches the period of natural thrust stand motion. Calibration data were obtained using a modified hanging pendulum thrust stand previously used for steady-state thrust measurements. Data were obtained for varying impulse bit at constant pulse frequency and for varying pulse frequency. The two data sets exhibit excellent quantitative agreement with each other as the constant relating average deflection and average thrust match within the errors on the linear regression curve fit of the data. Quantitatively, the error on the calibration coefficient is roughly 1% of the coefficient value.

  13. Chemical etching method assisted double-pulse LIBS for the analysis of silicon crystals

    NASA Astrophysics Data System (ADS)

    Khalil, A. A. I.

    2015-06-01

    Two Nd:YAG lasers working in pulsed modes are combined in the same direction (collinear arrangement) to focus on silicon (Si) crystals in reduced oxygen atmosphere (0.1 mbar) for double-pulse laser-induced breakdown spectroscopy (DP-LIBS) system. Silicon crystals of (100) and (111) orientations were investigated, and Si samples were measured either without prior treatment ("untreated") or after fabrication of nano-pores ("treated"). Nano-pores are produced by metal coating and by chemical etching. DP-LIBS spectra were compared for different Si samples (untreated, treated, (100) and (111) orientations), for double-pulse (DP) (with 266 nm pulse followed by 1064 nm pulse) excitation and for different delay times (times between the excitation laser pulse and the detection ICCD gate); treatment by chemical etching has been studied as well. The intensity of the atomic line Si I at 288.16 nm was enhanced by a factor of about three by using the DP-LIBS signals as compared to the single-pulse (SP) signal which could increase the sensitivity of the LIBS technique. This study proved that an optimized value of the etching time of Si during etching by chemical processes and short delay times are required. Plasma parameters [the electron temperature ( T e) and the electron number density ( N e)] were calculated from measured SP- and DP-LIBS spectra. The most important result of this study is the much higher DP-LIBS intensity observed on Si (100) as compared to Si (111) for measurements under the same experimental conditions. This study could provide important reference data for the design and optimization of DP-LIBS systems involved in plasma-facing components diagnostics.

  14. A Time-Domain Reflectometry Method with Variable Needle Pulse Width for Measuring the Dielectric Properties of Materials

    PubMed Central

    Wilczek, Andrzej; Szypłowska, Agnieszka; Kafarski, Marcin; Skierucha, Wojciech

    2016-01-01

    Time-domain reflectometry (TDR) methods used for measuring the dielectric properties of materials mostly utilize step or needle electrical pulses of constant amplitudes and shapes. Our novel approach enables determining the dielectric relaxation time of a sample using the analysis of the amplitudes of reflected pulses of two widths, in addition to bulk dielectric permittivity and electrical conductivity commonly obtained by the TDR technique. The method was developed for various values of electrical conductivity and relaxation time using numerical simulations of a five-rod probe placed in a material with complex dielectric permittivity described by the Debye model with an added electrical conductivity term. The characterization of amplitudes of two pulses of selected widths was done with regard to the dielectric parameters of simulated materials. The required probe parameters were obtained solely from numerical simulations. Verification was performed for the probe placed in aqueous KCl solutions with 14 different electrical conductivity values. The determined relaxation time remained roughly constant and independent of electrical conductivity. The obtained electrical conductivity agreed with the reference values. Our results indicate that the relaxation time, dielectric permittivity and electrical conductivity of the tested solutions can be simultaneously determined using a simple analysis of the amplitude and reflection time of two needle pulses of different widths. PMID:26861318

  15. A Time-Domain Reflectometry Method with Variable Needle Pulse Width for Measuring the Dielectric Properties of Materials.

    PubMed

    Wilczek, Andrzej; Szypłowska, Agnieszka; Kafarski, Marcin; Skierucha, Wojciech

    2016-01-01

    Time-domain reflectometry (TDR) methods used for measuring the dielectric properties of materials mostly utilize step or needle electrical pulses of constant amplitudes and shapes. Our novel approach enables determining the dielectric relaxation time of a sample using the analysis of the amplitudes of reflected pulses of two widths, in addition to bulk dielectric permittivity and electrical conductivity commonly obtained by the TDR technique. The method was developed for various values of electrical conductivity and relaxation time using numerical simulations of a five-rod probe placed in a material with complex dielectric permittivity described by the Debye model with an added electrical conductivity term. The characterization of amplitudes of two pulses of selected widths was done with regard to the dielectric parameters of simulated materials. The required probe parameters were obtained solely from numerical simulations. Verification was performed for the probe placed in aqueous KCl solutions with 14 different electrical conductivity values. The determined relaxation time remained roughly constant and independent of electrical conductivity. The obtained electrical conductivity agreed with the reference values. Our results indicate that the relaxation time, dielectric permittivity and electrical conductivity of the tested solutions can be simultaneously determined using a simple analysis of the amplitude and reflection time of two needle pulses of different widths. PMID:26861318

  16. Using the compensated heat pulse method to monitor trends in stem water content in standing trees.

    PubMed

    López-Bernal, Álvaro; Testi, Luca; Villalobos, Francisco J

    2012-11-01

    Studying the dynamics of stem water content (θ) in living trees has an outstanding physiological interest but all the available techniques to measure θ exhibit major drawbacks. In this work, we present a new methodology to estimate variations in θ along with sap velocity using the compensated heat pulse (CHP) technique. One lab experiment was performed on several wooden blocks obtained from three different tree species. Samples were slowly dried and their moisture loss was monitored by both gravimetric approaches and time-domain reflectometry (TDR) or CHP probes in order to contrast the validity of our methodology (volumetric specific heat (VSH)-CHP) over a range of water contents. In addition, a field experiment was conducted to monitor θ fluctuations in standing olive trees (Olea europaea L. cv. 'Arbequina') growing under three different irrigation regimes. In the lab test, the actual θ values deduced gravimetrically differed from the estimates yielded by the VSH-CHP method. However, it could successfully track relative changes in the water stored for the range of θ expected in living wood. Furthermore, the field experiment showed a seasonal change in θ, which was similar in shape and magnitude to those reported in the literature for olive and other Mediterranean tree species. On the other hand, differences in the seasonal patterns of θ between irrigation treatments strongly corresponded with those of sap flow and some leaf water potential measurements. The results of this work suggest that the CHP technique could be employed to monitor the dynamics of both θ and sap flow simultaneously in standing trees and evidence that seasonal changes in θ might be used as a long-term water status indicator. PMID:23095949

  17. Experiments of glucose solution measurement based on the tunable pulsed laser induced photoacoustic spectroscopy method

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Liu, Guodong; Xiong, Zhihua; Huang, Zhen

    2015-07-01

    Photoacoustic spectroscopy (PAS) is a hybrid, well-established and promising detection technique that has widely applied into a lot of fields such as bio-medical, material and environment monitoring etc. PAS has high contrast and resolution because of combining the advantages of the pure-optical and the pure-acoustic. In this paper, a photoacoustic experiment of glucose solution induced by 532nm pumped Nd:YAG tunable pulsed laser with repetition rate of 20Hz and pulse width of 10ns is performed. The time-resolved photoacoustic signals of glucose solution induced by pulsed laser in the average time of 512 are obtained. And the photoacoustic experiments of different concentrations of glucose solutions and different wavelengths of pulsed laser are carried out in this paper. Experimental results demonstrate that the bipolar sine-wave profiles for the time-resolved photoacoustic signal of glucose solution are in good agreement with the past reported literatures. And the different absorbing coefficients of glucose solution can be gotten according to the slope of the first part of the time-resolved photoacoustic signals. In addition, the different acoustic velocities of glucose solution can also be gotten according to the shift change of the time-resolved photoacoustic peak values. Research results illustrate that the characteristic wavelengths, different optical and acoustic properties of glucose solution can be interpreted by the time-resolved and peak-to-peak photoacoustic signals induced by the pulsed laser.

  18. Accuracy of methods for detecting an irregular pulse and suspected atrial fibrillation: A systematic review and meta-analysis

    PubMed Central

    Coleman, Tim; Lewis, Sarah; Heneghan, Carl; Jones, Matthew

    2015-01-01

    Background Pulse palpation has been recommended as the first step of screening to detect atrial fibrillation. We aimed to determine and compare the accuracy of different methods for detecting pulse irregularities caused by atrial fibrillation. Methods We systematically searched MEDLINE, EMBASE, CINAHL and LILACS until 16 March 2015. Two reviewers identified eligible studies, extracted data and appraised quality using the QUADAS-2 instrument. Meta-analysis, using the bivariate hierarchical random effects method, determined average operating points for sensitivities, specificities, positive and negative likelihood ratios (PLR, NLR); we constructed summary receiver operating characteristic plots. Results Twenty-one studies investigated 39 interventions (n = 15,129 pulse assessments) for detecting atrial fibrillation. Compared to 12-lead electrocardiography (ECG) diagnosed atrial fibrillation, blood pressure monitors (BPMs; seven interventions) and non-12-lead ECGs (20 interventions) had the greatest accuracy for detecting pulse irregularities attributable to atrial fibrillation (BPM: sensitivity 0.98 (95% confidence interval (CI) 0.92–1.00), specificity 0.92 (95% CI 0.88–0.95), PLR 12.1 (95% CI 8.2–17.8) and NLR 0.02 (95% CI 0.00–0.09); non-12-lead ECG: sensitivity 0.91 (95% CI 0.86–0.94), specificity 0.95 (95% CI 0.92–0.97), PLR 20.1 (95% CI 12–33.7), NLR 0.09 (95% CI 0.06–0.14)). There were similar findings for smartphone applications (six interventions) although these studies were small in size. The sensitivity and specificity of pulse palpation (six interventions) were 0.92 (95% CI 0.85–0.96) and 0.82 (95% CI 0.76–0.88), respectively (PLR 5.2 (95% CI 3.8–7.2), NLR 0.1 (95% CI 0.05–0.18)). Conclusions BPMs and non-12-lead ECG were most accurate for detecting pulse irregularities caused by atrial fibrillation; other technologies may therefore be pragmatic alternatives to pulse palpation for the first step of atrial fibrillation screening

  19. Water Sorption and Gamma Radiolysis Studies for Uranium Oxides

    SciTech Connect

    Icenhour, A.S.

    2002-02-27

    During the development of a standard for the safe, long-term storage of {sup 233}U-containing materials, several areas were identified that needed additional experimental studies. These studies were related to the perceived potential for the radiolytic generation of large pressures or explosive concentrations of gases in storage containers. This report documents the results of studies on the sorption of water by various uranium oxides and on the gamma radiolysis of uranium oxides containing various amounts of sorbed moisture. In all of the experiments, {sup 238}U was used as a surrogate for the {sup 233}U. For the water sorption experiments, uranium oxide samples were prepared and exposed to known levels of humidity to establish the water uptake rate. Subsequently, the amount of water removed was studied by heating samples in a oven at fixed temperatures and by thermogravimetric analysis (TGA)/differential thermal analysis (DTA). It was demonstrated that heating at 650 C adequately removes all moisture from the samples. Uranium-238 oxides were irradiated in a {sup 60}Co source and in the high-gamma-radiation fields provided by spent nuclear fuel elements of the High Flux Isotope Reactor. For hydrated samples of UO{sub 3}, H{sub 2} was the primary gas produced; but the total gas pressure increase reached steady value of about 10 psi. This production appears to be a function of the dose and the amount of water present. Oxygen in the hydrated UO{sub 3} sample atmosphere was typically depleted, and no significant pressure rise was observed. Heat treatment of the UO{sub 3} {center_dot} xH{sub 2}O at 650 C would result in conversion to U{sub 3}O{sub 8} and eliminate the H{sub 2} production. For all of the U{sub 3}O{sub 8} samples loaded in air and irradiated with gamma radiation, a pressure decrease was seen and little, if any, H{sub 2} was produced--even for samples with up to 9 wt % moisture content. Hence, these results demonstrated that the efforts to remove trace

  20. Realizing up-conversion fluorescence tuning in lanthanide-doped nanocrystals by femtosecond pulse shaping method

    PubMed Central

    Zhang, Shian; Yao, Yunhua; Shuwu, Xu; Liu, Pei; Ding, Jingxin; Jia, Tianqing; Qiu, Jianrong; Sun, Zhenrong

    2015-01-01

    The ability to tune color output of nanomaterials is very important for their applications in laser, optoelectronic device, color display and multiplexed biolabeling. Here we first propose a femtosecond pulse shaping technique to realize the up-conversion fluorescence tuning in lanthanide-doped nanocrystals dispersed in the glass. The multiple subpulse formation by a square phase modulation can create different excitation pathways for various up-conversion fluorescence generations. By properly controlling these excitation pathways, the multicolor up-conversion fluorescence can be finely tuned. This color tuning by the femtosecond pulse shaping technique is realized in single material by single-color laser field, which is highly desirable for further applications of the lanthanide-doped nanocrystals. This femtosecond pulse shaping technique opens an opportunity to tune the color output in the lanthanide-doped nanocrystals, which may bring a new revolution in the control of luminescence properties of nanomaterials. PMID:26290391

  1. A simple method of calculating pulse amplitudes and shapes arising from reflection from linear segments

    SciTech Connect

    Erickson, S.A. Jr.

    1988-01-02

    A new formulation for the amplitude and pulse shape from reflections from a linear segment for a bistatic planar geometry is presented. The formulation is useful in calculating reverberation from high intensity signals in an deep ocean basin where long range propagation can occur. This reverberation is important in calculating the acoustic interference to sonar arising from the detonation of nuclear or large chemical explosives, and for modeling long range active sonar. The reflections computed with the new formulation are significantly different from those of earlier versions of the reverberation model, with pulses generally shorter and more intense, leading to predictions of louder but more sporadic reverberation than previously estimated. 9 refs

  2. A method for removal of CO from exhaust gas using pulsed corona discharge.

    PubMed

    Li, X; Yang, L; Lei, Y; Wang, J; Lu, Y

    2000-10-01

    An experimental study of the oxidation of CO in exhaust gas from a motorcycle has been carried out using plasma chemical reactions in a pulsed corona discharge. In the process, some main parameters, such as the initial CO concentration, amplitude and frequency of pulses, residence time, reactor volume, and relative humidity (RH), as well as their effects on CO removal characteristics, were investigated. O3, which is beneficial to reducing CO, was produced during CO removal. When the exhaust gas was at ambient temperature, more than 80% CO removal efficiency was realized at an initial concentration of 288 ppm in a suitable range of the parameters. PMID:11288300

  3. Application of the multiple signal classification (MUSIC) method for one-pulse burst-echo Doppler sonar data

    NASA Astrophysics Data System (ADS)

    Iwata, Tetsuo; Goto, Yoji; Susaki, Hironori

    2001-12-01

    In order to estimate ship velocity, we have applied the multiple signal classification (MUSIC) method to one-pulse burst-echo Doppler sonar data. The MUSIC method enabled us to estimate the Doppler frequency shift precisely under a low-signal-to-noise ratio (SNR) situation even from a one-pulse burst-echo signal with small data points. In simulation experiments, a signal frequency component of f = 16 Hz could be extracted from N = 128 data-point data under a 40% Gaussian-distributed additive noise with a sampling frequency fs = 2048 Hz. From actual one-pulse burst-echo signal data of N = 128 points, a Doppler frequency shift of Δf = 1.45 kHz, corresponding to a ship velocity 1.76 knots, was clearly detected, the frequency resolution of which was almost impossible to attain by the conventional Fourier transform (FFT) method. We found that the MUSIC method was useful especially for estimating the ship velocity at a very low speed.

  4. Fundamental aspects of pulse phase-locked loop technology-based methods for measurement of ultrasonic velocity

    NASA Technical Reports Server (NTRS)

    Yost, William T.; Cantrell, John H.; Kushnick, Peter W.

    1992-01-01

    A new instrument based on a constant frequency pulse phase-locked loop concept has been developed to accurately measure the ultrasonic phase velocity in condensed matter. Measurements of the sound velocity in ultrapure water are reported in which both damped and undamped transducers are used with the instrument together with reflectors of various thicknesses placed in the sound propagation path. An analysis of measurements made with the new instrument and similar measurements, taken under identical experimental conditions, using a popular variable frequency pulsed-phase-locked loop instrument is reported. Uncertainties in both measurement systems are analyzed and discussed. A method for measuring inherent phase shifts, not addressed by previous investigations, within the variable frequency pulsed phase-locked loop system and a derivation of the equations that govern the overall use of variable frequency systems using phase-sensitive comparisons are presented. The effects of a finite pulse length on the measurements of phase velocity in dispersive media are addressed in detail.

  5. Fundamental aspects of pulse phase-locked loop technology-based methods for measurement of ultrasonic velocity

    SciTech Connect

    Yost, William T; Cantrell, John H; Kushnick, Peter W

    1992-03-01

    A new instrument based on a constant frequency pulse phase-locked loop concept has been developed to accurately measure the ultrasonic phase velocity in condensed matter. Measurements of the sound velocity in ultrapure water are reported in which both damped and undamped transducers are used with the instrument together with reflectors of various thicknesses placed in the sound propagation path. An analysis of measurements made with the new instrument and similar measurements, taken under identical experimental conditions, using a popular variable frequency pulsed-phase-locked loop instrument is reported. Uncertainties in both measurement systems are analyzed and discussed. A method for measuring inherent phase shifts, not addressed by previous investigators, within the variable frequency pulsed phase-locked loop system and a derivation of the equations that govern the overall use of variable frequency systems using phase-sensitive comparisons are presented. The effects of a finite pulse length on the measurements of phase velocity in dispersive media are addressed in detail.

  6. A remote and non-contact method for obtaining the blood-pulse waveform with a laser Doppler vibrometer

    NASA Astrophysics Data System (ADS)

    Desjardins, Candida L.; Antonelli, Lynn T.; Soares, Edward

    2007-02-01

    The use of lasers to remotely and non-invasively detect the blood pressure waveform of humans and animals would provide a powerful diagnostic tool. Current blood pressure measurement tools, such as a cuff, are not useful for burn and trauma victims, and animals require catheterization to acquire accurate blood pressure information. The purpose of our sensor method and apparatus invention is to remotely and non-invasively detect the blood pulse waveform of both animals and humans. This device is used to monitor an animal or human's skin in proximity to an artery using radiation from a laser Doppler vibrometer (LDV). This system measures the velocity (or displacement) of the pulsatile motion of the skin, indicative of physiological parameters of the arterial motion in relation to the cardiac cycle. Tests have been conducted that measures surface velocity with an LDV and a signal-processing unit, with enhanced detection obtained with optional hardware including a retro-reflector dot. The blood pulse waveform is obtained by integrating the velocity signal to get surface displacement using standard signal processing techniques. Continuous recording of the blood pulse waveform yields data containing information on cardiac health and can be analyzed to identify important events in the cardiac cycle, such as heart rate, the timing of peak systole, left ventricular ejection time and aortic valve closure. Experimental results are provided that demonstrates the current capabilities of the optical, non-contact sensor for the continuous, non-contact recording of the blood pulse waveform without causing patient distress.

  7. Radiolysis of alanine adsorbed in a clay mineral

    NASA Astrophysics Data System (ADS)

    Aguilar-Ovando, Ellen Y.; Negrón-Mendoza, Alicia

    2013-07-01

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically γ-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine.

  8. Pt and Pt/(Cu) Carbonyl clusters synthesized by radiolysis

    NASA Astrophysics Data System (ADS)

    Le Gratiet, B.; Remita, H.; Picq, G.; Delcourt, M. O.

    1996-02-01

    In the mixed solvent: 50/50% v/v water/2-propanol, [Pt 3(CO) 6] n2- clusters with n = 3-10 have been obtained by irradiating solutions containing K 2PtCl 4 under 1 atm CO. n is deduced from the very typical UV-visible and IR absorption spectra. The reduction occurs by a combined effect of CO and of the radicals produced by radiolysis (radiocatalysis). The synthesis is selective: the nuclearity n can be chosen by adjusting the dose (high doses yield low n values). Increasing the Pt salt concentration leads to CO-stabilized subcolloid particles. Intermetallic cluster compounds are expected from solutions containing two metal salts: bimetallic Pt/Cu carbonyl clusters have been obtained. Two distinct compounds have been characterized by their UV-visible spectra. Attempts with Pt/Ru and Pt/Sn systems were unsuccessful.

  9. Radiolysis of alanine adsorbed in a clay mineral

    SciTech Connect

    Aguilar-Ovando, Ellen Y.; Negron-Mendoza, Alicia

    2013-07-03

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically {gamma}-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine.

  10. A method towards simulating the total luminous flux of a monochromatic high power LED operated in a pulsed manner.

    PubMed

    Moolman, M C; Koek, W D; Urbach, H P

    2009-09-28

    High power light-emitting diodes (HPLEDs) are frequently being operated in a pulsed manner. The research presented here focuses on the optical, electrical and thermal behaviour of a HPLED under pulse width modulation (PWM), and has the following twofold aim. Firstly, investigating the temperature dependence of the HPLED's efficiency, where it was found that the exact method of operation and the definition of calculation is crucial when making claims. Secondly, we propose a method to simulate the absolute emitted luminous flux of a current driven HPLED under PWM. This is done by making use of experimentally determined characteristic parameters of the HPLED. This has as advantage that no further physical measurements are needed to investigate the HPLEDs behavior under numerous different PWM circumstances. PMID:19907530

  11. Method and apparatus for improved efficiency in a pulse-width-modulated alternating current motor drive

    DOEpatents

    Konrad, C.E.; Boothe, R.W.

    1996-01-23

    A scheme for optimizing the efficiency of an AC motor drive operated in a pulse-width-modulated mode provides that the modulation frequency of the power furnished to the motor is a function of commanded motor torque and is higher at lower torque requirements than at higher torque requirements. 6 figs.

  12. Method and apparatus for improved efficiency in a pulse-width-modulated alternating current motor drive

    DOEpatents

    Konrad, Charles E.; Boothe, Richard W.

    1994-01-01

    A scheme for optimizing the efficiency of an AC motor drive operated in a pulse-width-modulated mode provides that the modulation frequency of the power furnished to the motor is a function of commanded motor torque and is higher at lower torque requirements than at higher torque requirements.

  13. Method and apparatus for improved efficiency in a pulse-width-modulated alternating current motor drive

    DOEpatents

    Konrad, Charles E.; Boothe, Richard W.

    1996-01-01

    A scheme for optimizing the efficiency of an AC motor drive operated in a pulse-width-modulated mode provides that the modulation frequency of the power furnished to the motor is a function of commanded motor torque and is higher at lower torque requirements than at higher torque requirements.

  14. Method and apparatus for improved efficiency in a pulse-width-modulated alternating current motor drive

    DOEpatents

    Konrad, C.E.; Boothe, R.W.

    1994-02-15

    A scheme for optimizing the efficiency of an AC motor drive operated in a pulse-width-modulated mode provides that the modulation frequency of the power furnished to the motor is a function of commanded motor torque and is higher at lower torque requirements than at higher torque requirements. 6 figures.

  15. Solid state radiolysis of amino acids in an astrochemical perspective

    NASA Astrophysics Data System (ADS)

    Cataldo, Franco; Angelini, Giancarlo; Iglesias-Groth, Susana; Manchado, Arturo

    2011-01-01

    The aliphatic amino acids L-alanine and L-leucine and the aromatic amino acids L-phenylalanine, L-tyrosine and L-tryptophan were irradiated in the solid state to a dose of 3.2 MGy. The degree of decomposition was measured by differential scanning calorimetry (DSC). Furthermore the degree of radioracemization was measured by optical rotatory dispersion (ORD) spectroscopy. From the DSC measurement a radiolysis rate constant k and the half life T1/2 for each amino acid have been determined and extrapolated to a dose of 14 MGy, which corresponds to the expected total dose delivered by the decay of radionuclides to the organic molecules present in comets and asteroids in 4.6×109 years, the age of the Solar System. It is shown that all the amino acids studied can survive a radiation dose of 14 MGy although they are reduced to 1/4-1/5 of their original value they had at the beginning of the history of the Solar System. Consequently, the amount of alanine or leucine found today in the meteorites known as carbonaceous chondrites is just 1/4-1/5 of the amount originally present at the epoch of the formation of the Solar System 4.6×109 years ago. Among the amino acids studied, tyrosine shows the highest radiation resistance while tryptophan does not combine its relatively high radiation resistance with an elevated level of radioracemization resistance. Apart from the exception of tryptophan, it is shown that the radiolysis rate constants k of all the amino acids studied are in reasonable agreement with the radioracemization rate constant krac.

  16. Method for optimizing output in ultrashort-pulse multipass laser amplifiers with selective use of a spectral filter

    DOEpatents

    Backus, Sterling J.; Kapteyn, Henry C.

    2007-07-10

    A method for optimizing multipass laser amplifier output utilizes a spectral filter in early passes but not in later passes. The pulses shift position slightly for each pass through the amplifier, and the filter is placed such that early passes intersect the filter while later passes bypass it. The filter position may be adjust offline in order to adjust the number of passes in each category. The filter may be optimized for use in a cryogenic amplifier.

  17. Development of Measurement Methods for Detection of Special Nuclear Materials using D-D Pulsed Neutron Source

    NASA Astrophysics Data System (ADS)

    Misawa, Tsuyoshi; Takahashi, Yoshiyuki; Yagi, Takahiro; Pyeon, Cheol Ho; Kimura, Masaharu; Masuda, Kai; Ohgaki, Hideaki

    2015-10-01

    For detection of hidden special nuclear materials (SNMs), we have developed an active neutron-based interrogation system combined with a D-D fusion pulsed neutron source and a neutron detection system. In the detection scheme, we have adopted new measurement techniques simultaneously; neutron noise analysis and neutron energy spectrum analysis. The validity of neutron noise analysis method has been experimentally studied in the Kyoto University Critical Assembly (KUCA), and was applied to a cargo container inspection system by simulation.

  18. Reactivity of imidazoles in pulse and γ-irradiated liquid and frozen systems

    NASA Astrophysics Data System (ADS)

    Kalecińska, Elżbieta; Kaleciński, Jerzy

    1996-03-01

    The reactivity and decomposition of imidazoles have been studied in methanol, methanol-water and chlorides-methanol-water systems. It has been shown by pulse radiolysis and steady-state experiments that imidazoles are medium reactive towards electrons and rather low reactive towards radicals, particularly in chloride-methanol-water frozen matrices.

  19. Applying the Active Heating Pulse DFOT Method to Drip Irrigation. Characterization of a wetting bulb in drip emitter

    NASA Astrophysics Data System (ADS)

    Benitez-Buelga, J.; Rodriguez-Sinobas, L.; María Gil-Rodríguez, M.; Sayde, C.; Selker, J. S.

    2011-12-01

    The use of Distributed Fiber Optic Temperature Measurement (DFOT) method for estimating temperature variation along a cable of fiber optic has been largely reported in multiple environmental applications. Recently , its usage has been combined with an active heating pulses technique- measurement of the temperature increase when a certain amount of tension is applied to the stainless jacket surrounding the fiber optic cable-in order to estimate soil water content in field and laboratory conditions with great accuracy . Thus, a methodology potentially capable of monitoring spatial variability and accurately estimates soil water content is created. This study presents a direct application of the Active Heated DFOT method for measuring soil water distribution and wetting bulb of a single drip emitter. In order to do so, three concentric helixes of fiber optics were placed in a hexagonal column of Plexiglas of 0.5 m base radius and 0.6 m height. After being filled up with air-dried loamy soil of controlled bulk density, a pressure compensating drip emitter of 2 L/h discharge was placed on top of the soil column. For an irrigation time of 5 hours and 40 min, 21 heating pulses of 2 minutes and 20W/m, were applied. In addition, soil samples after each heat pulse were also collected. Results showed the potential of this method for monitoring soil water behavior during irrigation and also its capability to estimate soil water content with accuracy.

  20. Multiple headspace-solid-phase microextraction as a powerful tool for the quantitative determination of volatile radiolysis products in a multilayer food packaging material sterilized with γ-radiation.

    PubMed

    de Oliveira, Cristiane Patrícia; Rodriguez-Lafuente, Angel; Soares, Nilda de Fátima Ferreira; Nerin, Cristina

    2012-06-29

    A method consisting of multiple headspace solid-phase microextraction followed by gas chromatography-mass spectrometry analysis was developed and used to determine the main volatile radiolysis products formed by γ-irradiation of flexible multilayer food packaging samples. The developed method allows the use of solid-phase microextraction in the quantification of compounds from plastic solid samples. A screening of volatiles in the γ-irradiated and non-irradiated films was performed and 29 compounds were identified in the irradiated packaging, 17 of which were absent in the non-irradiated samples. The main volatile radiolysis products identified were: 1,3-di-tert-butylbenzene; 2,6-di-tert-butyl-1,4-benzoquinone; 4-tert-butyl-phenol and the off-odor compounds butanoic acid and valeric acid. These volatile radiolysis compounds were determined with the proposed method and the results are shown and discussed. Solid-liquid extraction and headspace solid-phase microextraction methods were also studied for comparative purposes. The automated solvent-free multiple HSPME technique here presented can be used to quantify the radiolysis compounds in irradiated plastic solid samples in a simple way with the advantages of being free from matrix influence and environmentally friendly. PMID:22609166

  1. Laser triggered injection of electrons in a laser wakefield accelerator with the colliding pulse method

    SciTech Connect

    Nakamura, K.; Fubiani, G.; Geddes, C.G.R.; Michel, P.; van Tilborg, J.; Toth, C.; Esarey, E.; Schroeder, C.B.; Leemans, W.P.

    2004-10-22

    An injection scheme for a laser wakefield accelerator that employs a counter propagating laser (colliding with the drive laser pulse, used to generate a plasma wake) is discussed. The threshold laser intensity for electron injection into the wakefield was analyzed using a heuristic model based on phase-space island overlap. Analysis shows that the injection can be performed using modest counter propagating laser intensity a{sub 1} < 0.5 for a drive laser intensity of a{sub 0} = 1.0. Preliminary experiments were preformed using a drive beam and colliding beam. Charge enhancement by the colliding pulse was observed. Increasing the signal-to-noise ratio by means of a preformed plasma channel is discussed.

  2. A comparison of three types of pulse tube refrigerators - New methods for reaching 60 K

    NASA Technical Reports Server (NTRS)

    Radebaugh, Ray; Zimmerman, James; Smith, David R.; Louie, Beverly

    1986-01-01

    The three types of pulse tube refrigerator, namely the resonant, basic, and orifice designs, are compared with each other and with such common refrigerators as the Joule-Thomson and Stirling types, using an apparatus able to measure their intrinsic behavior from 30 to 300 K. Orifice pulse tubes are found capable of reaching 60 K temperature drops in a single stage. Additional advantages of the type are (1) a single, room-temperature moving part, (2) the use of moderate pressures and pressure ratios, (3) good intrinsic efficiency, and (4) the ability to operate several stages from the same pressure wave generator. The low refrigeration rate/unit mass flow means, however, that better regenerator units are required.

  3. Effect of Catalytic Pyrolysis Conditions Using Pulse Current Heating Method on Pyrolysis Products of Wood Biomass

    PubMed Central

    Honma, Sensho; Hata, Toshimitsu; Watanabe, Takashi

    2014-01-01

    The influence of catalysts on the compositions of char and pyrolysis oil obtained by pyrolysis of wood biomass with pulse current heating was studied. The effects of catalysts on product compositions were analyzed using GC-MS and TEM. The compositions of some aromatic compounds changed noticeably when using a metal oxide species as the catalyst. The coexistence or dissolution of amorphous carbon and iron oxide was observed in char pyrolyzed at 800°C with Fe3O4. Pyrolysis oil compositions changed remarkably when formed in the presence of a catalyst compared to that obtained from the uncatalyzed pyrolysis of wood meal. We observed a tendency toward an increase in the ratio of polyaromatic hydrocarbons in the pyrolysis oil composition after catalytic pyrolysis at 800°C. Pyrolysis of biomass using pulse current heating and an adequate amount of catalyst is expected to yield a higher content of specific polyaromatic compounds. PMID:25614894

  4. Method for controlling energy density for reliable pulsed laser deposition of thin films

    SciTech Connect

    Dowden, P. C. E-mail: qxjia@lanl.gov; Bi, Z.; Jia, Q. X. E-mail: qxjia@lanl.gov

    2014-02-15

    We have established a methodology to stabilize the laser energy density on a target surface in pulsed laser deposition of thin films. To control the focused laser spot on a target, we have imaged a defined aperture in the beamline (so called image-focus) instead of focusing the beam on a target based on a simple “lens-focus.” To control the laser energy density on a target, we have introduced a continuously variable attenuator between the output of the laser and the imaged aperture to manipulate the energy to a desired level by running the laser in a “constant voltage” mode to eliminate changes in the lasers’ beam dimensions. This methodology leads to much better controllability/reproducibility for reliable pulsed laser deposition of high performance electronic thin films.

  5. Effect of catalytic pyrolysis conditions using pulse current heating method on pyrolysis products of wood biomass.

    PubMed

    Honma, Sensho; Hata, Toshimitsu; Watanabe, Takashi

    2014-01-01

    The influence of catalysts on the compositions of char and pyrolysis oil obtained by pyrolysis of wood biomass with pulse current heating was studied. The effects of catalysts on product compositions were analyzed using GC-MS and TEM. The compositions of some aromatic compounds changed noticeably when using a metal oxide species as the catalyst. The coexistence or dissolution of amorphous carbon and iron oxide was observed in char pyrolyzed at 800 °C with Fe3O4. Pyrolysis oil compositions changed remarkably when formed in the presence of a catalyst compared to that obtained from the uncatalyzed pyrolysis of wood meal. We observed a tendency toward an increase in the ratio of polyaromatic hydrocarbons in the pyrolysis oil composition after catalytic pyrolysis at 800 °C. Pyrolysis of biomass using pulse current heating and an adequate amount of catalyst is expected to yield a higher content of specific polyaromatic compounds. PMID:25614894

  6. Antimicrobial activity of biopolymer-antibiotic thin films fabricated by advanced pulsed laser methods

    NASA Astrophysics Data System (ADS)

    Cristescu, R.; Popescu, C.; Dorcioman, G.; Miroiu, F. M.; Socol, G.; Mihailescu, I. N.; Gittard, S. D.; Miller, P. R.; Narayan, R. J.; Enculescu, M.; Chrisey, D. B.

    2013-08-01

    We report on thin film deposition by matrix assisted pulsed laser evaporation (MAPLE) of two polymer-drug composite thin film systems. A pulsed KrF* excimer laser source (λ = 248 nm, τ = 25 ns, ν = 10 Hz) was used to deposit composite thin films of poly(D,L-lactide) (PDLLA) containing several gentamicin concentrations. FTIR spectroscopy was used to demonstrate that MAPLE-transferred materials exhibited chemical structures similar to those of drop cast materials. Scanning electron microscopy data indicated that MAPLE may be used to fabricate thin films of good morphological quality. The activity of PDLLA-gentamicin composite thin films against Staphylococcus aureus bacteria was demonstrated using drop testing. The influence of drug concentration on microbial viability was also assessed. Our studies indicate that polymer-drug composite thin films prepared by MAPLE may be used to impart antimicrobial activity to implants, medical devices, and other contact surfaces.

  7. Pulse methods in 1D and 2D liquid-phase NMR

    SciTech Connect

    Brey, W.S.

    1988-01-01

    State-of-the-art nuclear magnetic resonance spectrometers are capable of performing an array of multiple-pulse one-dimensional and two-dimensional experiments. These experiments can provide detailed information about the structure, dynamics, and reactions of molecules. However, their successful application to chemical problems requires that the chemist have some knowledge of the various experiments and the information they can provide. This book, written by authorities in the field, provides such information for both the specialist and the nonspecialist.

  8. An Improved Method of Mitigating Laser Induced Surface Damage Growth in Fused Silica Using a Rastered, Pulsed CO2 Laser

    SciTech Connect

    Bass, I L; Guss, G M; Nostrand, M J; Wegner, P L

    2010-10-21

    A new method of mitigating (arresting) the growth of large (>200 m diameter and depth) laser induced surface damage on fused silica has been developed that successfully addresses several issues encountered with our previously-reported large site mitigation technique. As in the previous work, a tightly-focused 10.6 {micro}m CO{sub 2} laser spot is scanned over the damage site by galvanometer steering mirrors. In contrast to the previous work, the laser is pulsed instead of CW, with the pulse length and repetition frequency chosen to allow substantial cooling between pulses. This cooling has the important effect of reducing the heat-affected zone capable of supporting thermo-capillary flow from scale lengths on the order of the overall scan pattern to scale lengths on the order of the focused laser spot, thus preventing the formation of a raised rim around the final mitigation site and its consequent down-stream intensification. Other advantages of the new method include lower residual stresses, and improved damage threshold associated with reduced amounts of redeposited material. The raster patterns can be designed to produce specific shapes of the mitigation pit including cones and pyramids. Details of the new technique and its comparison with the previous technique will be presented.

  9. Study of Artifact-Resistive Technology Based on a Novel Dual Photoplethysmography Method for Wearable Pulse Rate Monitors.

    PubMed

    Zhou, Congcong; Feng, Jingjie; Hu, Jun; Ye, Xuesong

    2016-03-01

    Pulse rate is one of the major physiological parameters for monitoring of cardiovascular conditions or excise states during daily life. However it is difficult to precisely measure the exact pulse rates as photoplethysmography (PPG) is easy to be affected by motion artifacts. Instead of using accelerometers followed by algorithms such as least mean square (LMS), recursive least square (RLS) and independent component analysis (ICA) or other equipment such as complex laser systems to measure displacement directly, a novel motion artifact estimation method which had lower computational complexity and higher signal dynamic range was studied and implemented, where a differential channel following green and red light PPG channels was applied to reduce the motion artifact caused by displacement of light emitting diode (LED), photo diode (PD) and tissue deformation before the analog signal was converted to digital form. A miniaturized, battery powered wrist worn artifact-resistive pulse rates monitoring system (PRMS) was presented to verify the proposed method. Four kinds of motions were performed and the results showed that the differential channel improved the morphology of the PPG signal and appeared to be artifact resistive during motions through light intensity control and high gain-phase consistency circuit design here. PMID:26645320

  10. Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses

    SciTech Connect

    Bionta, M. R.; Hartmann, N.; Weaver, M.; French, D.; Glownia, J. M.; Bostedt, C.; Chollet, M.; Ding, Y.; Fritz, D. M.; Fry, A. R.; Krzywinski, J.; Lemke, H. T.; Messerschmidt, M.; Schorb, S.; Zhu, D.; White, W. E.; Nicholson, D. J.; Cryan, J. P.; Baker, K.; Kane, D. J.; and others

    2014-08-15

    The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10–100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for “measure-and-sort” at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses.

  11. Ultrasonic Direction Measurement Method Using Sensitivity Compensated Transmitting Signal and Pulse Compression

    NASA Astrophysics Data System (ADS)

    Chimura, Dai; Toh, Ryo; Motooka, Seiichi

    We have studied high resolution pulse compression technique for ultrasonic pulse-echo measurement. To acquire broader and flatter spectrum, a Sensitivity Compensate Transmitting (SCT) signal was proposed. The SCT signal is calculated from inversed filtering of received signal. Here, two types SCT signal are proposed. As a Sensitivity Compensated AM (SCAM) signal, an amplitude modulated chirp wave is proposed. Furthermore, for higher Signal to Noise Ratio (SNR), a non-linear FM signal is proposed as a Sensitivity Compensate FM (SCFM) signal. In this paper, effectiveness of the SCT signal on 2-D direction measurement is discussed. By using the SCT signal, the time resolution of compressed pulse is improved, and accuracies of direction measurement using the SCT signal are improved than that of using the chirp wave. Furthermore, by using the SCFM signal, accuracy of direction measurement is improved than that of using the SCAM signal when the target is located at the position where the SNR of received signal is lower.

  12. Quickbird Satellite in-orbit Modulation Transfer Function (MTF) Measurement Using Edge, Pulse and Impulse Methods for Summer 2003

    NASA Technical Reports Server (NTRS)

    Helder, Dennis; Choi, Taeyoung; Rangaswamy, Manjunath

    2005-01-01

    The spatial characteristics of an imaging system cannot be expressed by a single number or simple statement. However, the Modulation Transfer Function (MTF) is one approach to measure the spatial quality of an imaging system. Basically, MTF is the normalized spatial frequency response of an imaging system. The frequency response of the system can be evaluated by applying an impulse input. The resulting impulse response is termed the Point Spread function (PSF). This function is a measure of the amount of blurring present in the imaging system and is itself a useful measure of spatial quality. An underlying assumption is that the imaging system is linear and shift-independent. The Fourier transform of the PSF is called the Optical Transfer Function (OTF) and the normalized magnitude of the OTF is the MTF. In addition to using an impulse input, a knife-edge in technique has also been used in this project. The sharp edge exercises an imaging system at all spatial frequencies. The profile of an edge response from an imaging system is called an Edge Spread Function (ESF). Differentiation of the ESF results in a one-dimensional version of the Point Spread Function (PSF). Finally, MTF can be calculated through use of Fourier transform of the PSF as stated previously. Every image includes noise in some degree which makes MTF of PSF estimation more difficult. To avoid the noise effects, many MTF estimation approaches use smooth numerical models. Historically, Gaussian models and Fermi functions were applied to reduce the random noise in the output profiles. The pulse-input method was used to measure the MTF of the Landsat Thematic Mapper (TM) using 8th order even functions over the San Mateo Bridge in San Francisco, California. Because the bridge width was smaller than the 30-meter ground sample distance (GSD) of the TM, the Nyquist frequency was located before the first zero-crossing point of the sinc function from the Fourier transformation of the bridge pulse. To avoid

  13. Low noise measurement system for determination of the critical currents in superconducting tapes by a pulse method.

    PubMed

    Ciszek, M; Trojanowski, S

    2011-11-01

    Steady state measurements of the high critical currents in superconducting composite wires and tapes might be burdened with some errors. The origin of the errors is mainly associated with the Joule heat generated at current leads contacts, which at high transport currents can considerably increase temperature of an investigated sample wire. To avoid this unwanted heating phenomenon pulsed current methods are widely used. A waveform of the current pulse is usually shaped by means of a series RLC circuit with the subcritical dumping condition. Measurement results (i.e., a value of current peak, its time derivative, and a voltage drop along a superconducting sample) are recorded by means of a 4-channels, 12-bit resolution, 50 ns sampling time, digital recorder. Very low noise, broadband, voltage preamplifiers, based on rf bipolar transistors, were designed and fabricated. From the data, current-voltage characteristics are plotted and then the critical currents of investigated tapes are determined. Presented in the work our home-made, low noise, measurement setup allows to obtain a current pulse of about 4000 A at duration time of several milliseconds. PMID:22128996

  14. Modulation of molecular hybridization and charge screening in a carbon nanotube network channel using the electrical pulse method.

    PubMed

    Woo, Jun-Myung; Kim, Seok Hyang; Chun, Honnggu; Kim, Sung Jae; Ahn, Jinhong; Park, Young June

    2013-09-21

    In this paper, we investigate the effect of electrical pulse bias on DNA hybridization events in a biosensor platform, using a Carbon Nanotube Network (CNN) and Gold Nano Particles (GNP) as an electrical channel. The scheme provides both hybridization rate enhancement of bio molecules, and electrical measurement in a transient state to avoid the charge screening effect, thereby significantly improving the sensitivity. As an example, the probe DNA molecules oscillate with pulse trains, resulting in the enhancement of DNA hybridization efficiency, and accordingly of the sensor performances in Tris-EDTA (TE) buffer solution, by as much as over three times, compared to the non-biasing conditions. More importantly, a wide dynamic range of 10(6) (target-DNA concentration from 5 pM to 5 μM) is achieved in human serum. In addition, the pulse biasing method enables one to obtain the conductance change, before the ions within the Electrical Double Layer (EDL) are redistributed, to avoid the charge screening effect, leading to an additional sensitivity enhancement. PMID:23900200

  15. Lyapunov method and analysis of the emerging repetitively pulsed regime in semiconductor lasers with delayed feedback

    SciTech Connect

    Napartovich, A P; Sukharev, Aleksandr G

    2011-03-31

    We study the nature of transition from stationary lasing to pulse-periodic oscillations when the phase of the delayed feedback and the diode laser pump current change. The appearance of oscillations can take place under the scenarios of soft or hard excitation of oscillations. We propose a semi-analytical approach to identify the nature of the transition and to determine the dynamic characteristics and stability of the arising spike regime with a change in the external parameters. Direct integration of the Lang - Kobayashi equations showed an acceptable accuracy of this approach. (control of laser radiation parameters)

  16. Observation of vasculature alternation by intense pulsed light combined with physicochemical methods.

    PubMed

    Son, Taeyoon; Kang, Heesung; Jung, Byungjo

    2016-05-01

    Intense pulsed light (IPL) with low energy insufficient to completely destroy a vasculature was applied to rabbit ears to investigate vasculature alteration. Glycerol was combined with IPL to enhance the transfer efficacy of IPL energy. Both trans-illumination and laser speckle contrast images were obtained and analyzed after treatment. The application of IPL and glycerol combination induced vasodilation and improvement in blood flow. Moreover, such phenomenon was maintained over time. IPL may be applied to treat blood circulatory diseases by inducing vasodilation and to improve blood flow. PMID:26776941

  17. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, David A.; Keller, Richard A.

    1985-01-01

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10.sup.-5 cm.sup.-1 has been demonstrated using this technique.

  18. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1982-06-08

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be rlated to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10/sup -5/ cm/sup -1/ has been demonstrated using this technique.

  19. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1985-10-01

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10[sup [minus]5] cm[sup [minus]1] has been demonstrated using this technique. 6 figs.

  20. Application of wavelet filtering and Barker-coded pulse compression hybrid method to air-coupled ultrasonic testing

    NASA Astrophysics Data System (ADS)

    Zhou, Zhenggan; Ma, Baoquan; Jiang, Jingtao; Yu, Guang; Liu, Kui; Zhang, Dongmei; Liu, Weiping

    2014-10-01

    Air-coupled ultrasonic testing (ACUT) technique has been viewed as a viable solution in defect detection of advanced composites used in aerospace and aviation industries. However, the giant mismatch of acoustic impedance in air-solid interface makes the transmission efficiency of ultrasound low, and leads to poor signal-to-noise (SNR) ratio of received signal. The utilisation of signal-processing techniques in non-destructive testing is highly appreciated. This paper presents a wavelet filtering and phase-coded pulse compression hybrid method to improve the SNR and output power of received signal. The wavelet transform is utilised to filter insignificant components from noisy ultrasonic signal, and pulse compression process is used to improve the power of correlated signal based on cross-correction algorithm. For the purpose of reasonable parameter selection, different families of wavelets (Daubechies, Symlet and Coiflet) and decomposition level in discrete wavelet transform are analysed, different Barker codes (5-13 bits) are also analysed to acquire higher main-to-side lobe ratio. The performance of the hybrid method was verified in a honeycomb composite sample. Experimental results demonstrated that the proposed method is very efficient in improving the SNR and signal strength. The applicability of the proposed method seems to be a very promising tool to evaluate the integrity of high ultrasound attenuation composite materials using the ACUT.

  1. Accuracy improvement in leak detection of charcoal adsorbers by halide pulse integration method

    SciTech Connect

    Kovach, B.J.; Banks, E.M.

    1997-08-01

    Due to the phaseout of the supply of R-11, which is used as a charcoal adsorber leak-testing agent, several new substitutes have been suggested and tested. Pulse testing using agents with higher boiling points produced longer response times (due to prolonged evaporation and dispersion times). This longer evaporation time alters the pulse shape and lowers the peak concentration. Since the dispersion and evaporation time under different ambient condition are unpredictable, the peak concentration becomes unpredictable as well. One way to eliminate this unpredictability is to determine the area under the curve (of concentration versus time) after test-agent injection rather than the peak concentration (height). This value should be independent of the injection time and evaporation rate as long as the volume of the test agent injected remains constant. Thus, tests were performed with a constant volume injection of test agent but with different injection times and evaporation rates. The area under the curve of concentration versus time was then compared with the peak concentration for each injection. 4 refs., 1 fig.

  2. Conditions for critical effects in the mass action kinetics equations for water radiolysis

    SciTech Connect

    Wittman, Richard S.; Buck, Edgar C.; Mausolf, Edward J.; McNamara, Bruce K.; Smith, Frances N.; Soderquist, Chuck Z.

    2014-12-26

    We report on a subtle global feature of the mass action kinetics equations for water radiolysis that results in predictions of a critical behavior in H2O2 and associated radical concentrations. While radiolysis kinetics has been studied extensively in the past, it is only in recent years that high speed computing has allowed the rapid exploration of the solution over widely varying dose and compositional conditions. We explore the radiolytic production of H2O2 under various externally fixed conditions of molecular H2 and O2 that have been regarded as problematic in the literature – specifically, “jumps” in predicted concentrations, and inconsistencies between predictions and experiments have been reported for alpha radiolysis. We computationally map-out a critical concentration behavior for alpha radiolysis kinetics using a comprehensive set of reactions. We then show that all features of interest are accurately reproduced with 15 reactions. An analytical solution for steady-state concentrations of the 15 reactions reveals regions in [H2] and [O2] where the H2O2 concentration is not unique – both stable and unstable concentrations exist. The boundary of this region can be characterized analytically as a function of G-values and rate constants independent of dose rate. Physically, the boundary can be understood as separating a region where a steady-state H2O2 concentration exists, from one where it does not exist without a direct decomposition reaction. We show that this behavior is consistent with reported alpha radiolysis data and that no such behavior should occur for gamma radiolysis. We suggest experiments that could verify or discredit a critical concentration behavior for alpha radiolysis and could place more restrictive ranges on G-values from derived relationships between them.

  3. Conditions for critical effects in the mass action kinetics equations for water radiolysis

    SciTech Connect

    Wittman, Richard S.; Buck, Edgar C.; Mausolf, Edward J.; McNamara, Bruce K.; Smith, Frances N.; Soderquist, Chuck Z.

    2014-11-25

    We report on a subtle global feature of the mass action kinetics equations for water radiolysis that results in predictions of a critical behavior in H2O2 and associated radical concentrations. While radiolysis kinetics has been studied extensively in the past, it is only in recent years that high speed computing has allowed the rapid exploration of the solution over widely varying dose and compositional conditions. We explore the radiolytic production of H2O2 under various externally fixed conditions of molecular H2 and O2 that have been regarded as problematic in the literature – specifically, “jumps” in predicted concentrations, and inconsistencies between predictions and experiments have been reported for alpha radiolysis. We computationally map-out a critical concentration behavior for alpha radiolysis kinetics using a comprehensive set of reactions. We then show that all features of interest are accurately reproduced with 15 reactions. An analytical solution for steady-state concentrations of the 15 reactions reveals regions in [H2] and [O2] where the H2O2 concentration is not unique – both stable and unstable concentrations exist. The boundary of this region can be characterized analytically as a function of G-values and rate constants independent of dose rate. Physically, the boundary can be understood as separating a region where a steady-state H2O2 concentration exists, from one where it does not exist without a direct decomposition reaction. We show that this behavior is consistent with reported alpha radiolysis data and that no such behavior should occur for gamma radiolysis. We suggest experiments that could verify or discredit a critical concentration behavior for alpha radiolysis and could place more restrictive ranges on G-values from derived relationships between them.

  4. DC-pulsed voltage electrochemical method based on duty cycle self-control for producing TERS gold tips

    NASA Astrophysics Data System (ADS)

    Vasilchenko, V. E.; Kharintsev, S. S.; Salakhov, M. Kh

    2013-12-01

    This paper presents a modified dc-pulsed low voltage electrochemical method in which a duty cycle is self tuned while etching. A higher yield of gold tips suitable for performing tip-enhanced Raman scattering (TERS) measurements is demonstrated. The improvement is caused by the self-control of the etching rate along the full surface of the tip. A capability of the gold tips to enhance a Raman signal is exemplified by TERS spectroscopy of single walled carbon nanotubes bundle, sulfur and vanadium oxide.

  5. Nanoclusters Synthesized by Synchrotron Radiolysis in Concert with Wet Chemistry

    PubMed Central

    Oyanagi, Hiroyuki; Orimoto, Yuuichi; Hayakawa, Kuniko; Hatada, Keisuke; Sun, Zhihu; Zhang, Ling; Yamashita, Kenichi; Nakamura, Hiroyuki; Uehara, Masato; Fukano, Atsuyuki; Maeda, Hideaki

    2014-01-01

    Wet chemical reduction of metal ions, a common strategy for synthesizing metal nanoparticles, strongly depends on the electric potential of the metal, and its applications to late transition metal clusters have been limited to special cases. Here, we describe copper nanoclusters grown by synchrotron radiolysis in concert with wet chemistry. The local structure of copper aggregates grown by reducing Cu(II) pentanedionate using synchrotron x-ray beam was studied in situ by x-ray absorption spectroscopy. A detailed analysis of the XANES and EXAFS spectra, compared with DFT calculations and full-potential non-muffin-tin multiple scattering calculations, identified the nanocluster as Cu13 with icosahedral symmetry. The novel “charged” nanoclusters tightly bound to electron-donating amido molecules, which formed as a result of photo-induced deprotonation of ligand amines, were stabilized by irradiation. Monodispersive deposition of nanoclusters was enabled by controlling the type and density of “monomers”, in remarkable contrast to the conventional growth of metallic nanoparticles. PMID:25425181

  6. Gamma and Neutron Radiolysis in the 21-PWR Waste Package

    SciTech Connect

    J.S. Tang

    2001-05-03

    The objective of this calculation is to compute gamma and neutron dose rates in order to determine the maximum radiolytic production of nitric acid and other chemical species inside the 21-PWR (pressurized-water reactor) waste package (WP). The scope of this calculation is limited to the time period between 5,000 and 100,000 years after emplacement. The information provided by the sketches attached to this calculation is that of the potential design for the type of WP considered in this calculation. The results of this calculation will be used to evaluate nitric acid corrosion of fuel cladding from radiolysis in the 21-PWR WP. This calculation was performed in accordance with the Technical Work Plan for: Waste Package Design Description for LA (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M&O) 2000a). AP-3.124, Calculations, is used to perform the calculation and develop the document. This calculation is associated with the total system performance assessment (TSPA) of which the spent fuel cladding integrity is to be evaluated.

  7. FPEX gamma-Radiolysis in the Presence of Nitric Acid

    SciTech Connect

    mincher

    2007-09-01

    Abstract: The solvent formulation known as FPEX (Fission Product Extraction) contains calix[4]arene-bis-(tert-octylbenzo-crown-6) (BOBCalixC6) for Cs extraction; 4,4’,(5’)-di-(t-butyldicyclohexano)-18-crown-6 (DtBuCH18C6) for Sr extraction; 1-(2,2,3,3,-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (Cs-7SB) modifier and trioctylamine (TOA) to aid in Cs stripping, all in Isopar L diluent. This formulation has favorable extraction efficiency for Cs and Sr from acidic solution, and was investigated here for ?-radiation stability. When FPEX was irradiated in contact with aqueous nitric acid, extraction efficiency decreased only slightly when irradiated to absorbed doses as high as 200 kGy. The color of the organic phase changed to a deep yellow-orange, and several new peaks related to radiolysis of the Cs-7SB modifier were detected by GC-ECD analysis. This had little effect on solvent extraction distribution ratios. Possible reasons for this unexpected robustness under conditions of high radiation and acidity are discussed.

  8. Radiolysis and hydrolysis of magnetically assisted chemical separation particles

    SciTech Connect

    Buchholz, B.A.; Nunez, L.; Vandegrift, G.F.

    1995-05-01

    The magnetically assisted chemical separation (MACS) process is designed to separate transuranic (TRU) elements out of high-level waste (HLW) or TRU waste. Magnetic microparticles (1--25 {mu}m) were coated with octyl (phenyl)N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) dissolved in tributyl phosphate (TBP) and tested for removing TRU elements from acidic nitrate solutions. The particles were contacted with nitric acid solutions and Hanford plutonium finishing plant (PFP) simulant, irradiated with a high intensity {sup 60}Co {gamma}-ray source, and evaluated for effectiveness in removing TRU elements from 2m HNO{sub 3} solutions. The resistance of the coatings and magnetic cores to radiolytic damage and hydrolytic degradation was investigated by irradiating samples of particles suspended in a variety of solutions with doses of up to 5 Mrad. Transmission electron microscopy (TEM), magnetic susceptibility measurements, and physical observations of the particles and suspension solutions were used to assess physical changes to the particles. Processes that affect the surface of the particles dramatically alter the binding sites for TRU in solution. Hydrolysis played a larger role than radiolysis in the degradation of the extraction capacity of the particles.

  9. Track effects in the radiolysis of aromatic liquids

    NASA Astrophysics Data System (ADS)

    LaVerne, Jay A.; Baidak, Aliaksandr

    2012-09-01

    The chemical effects induced by the track structure of heavy ions have been exploited to show that H2 production in the radiolysis of simple aromatic liquids (benzene, pyridine, toluene and aniline) is primarily due to second order processes. Similar dependences of H2 yields on the linear energy transfer, LET, for each of these compounds suggest a common mechanism for H2 formation. Furthermore, the yields of H2 are significant at very high LET and they approach that found with aliphatic compounds. Yields of "dimers" (biphenyl, bibenzyl, dipyridyl, and diphenylamine for benzene, toluene, pyridine, and aniline, respectively) have different dependences on LET reflecting the variety of pathways leading to their production. Bibenzyl formation in toluene exhibits a complex dependence on LET suggesting several competing pathways for its production whereas biphenyl formation in benzene is nearly independent of LET suggesting a unimolecular process. Dipyridyl, and diphenylamine yields in pyridine and aniline, respectively, decrease with increasing LET, which indicates that their precursor is being depleted.

  10. Variable frequency pulsed phase-locked loop method for measuring material nonlinearity

    NASA Technical Reports Server (NTRS)

    Yost, William T.; Cantrell, John H.

    1992-01-01

    The design of a pressure vessel with an isothermal volume to measure changes in the natural velocities of material continuously over a wide temperature range is reported. Highly sensitive pulsed phase-locked loop technology is used to measure the natural velocity of fatigued aluminum 2024-T4 as a function of pressure at different temperatures. Second derivative variations with respect to pressure and temperature are found to exhibit order-of-magnitude changes at a gauge pressure near 950 kPa at room temperature. This indicates a significant change in certain combinations of second-order and higher-order elastic constants at relatively low pressures. Fractional frequency change as a function of applied pressure for aluminum 2024-T4 with fatigue damage is illustrated.

  11. High power pulsed magnetron sputtering: A method to increase deposition rate

    SciTech Connect

    Raman, Priya McLain, Jake; Ruzic, David N; Shchelkanov, Ivan A.

    2015-05-15

    High power pulsed magnetron sputtering (HPPMS) is a state-of-the-art physical vapor deposition technique with several industrial applications. One of the main disadvantages of this process is its low deposition rate. In this work, the authors report a new magnetic field configuration, which produces deposition rates twice that of conventional magnetron's dipole magnetic field configuration. Three different magnet pack configurations are discussed in this paper, and an optimized magnet pack configuration for HPPMS that leads to a higher deposition rate and nearly full-face target erosion is presented. The discussed magnetic field produced by a specially designed magnet assembly is of the same size as the conventional magnet assembly and requires no external fields. Comparison of deposition rates with different power supplies and the electron trapping efficiency in complex magnetic field arrangements are discussed.

  12. Apparatus and method for tuned unsteady flow purging of high pulse rate spark gaps

    DOEpatents

    Thayer, III, William J.

    1990-01-01

    A spark gap switch apparatus is disclosed which is capable of operating at a high pulse rate which comprises an insulated housing; a pair of spaced apart electrodes each having one end thereof within a first bore formed in the housing and defining a spark gap therebetween; a pressure wave reflector in the first bore in the housing and spaced from the spark gap and capable of admitting purge flow; and a second enlarged bore contiguous with the first bore and spaced from the opposite side of the spark gap; whereby pressure waves generated during discharge of a spark across the spark gap will reflect off the wave reflector and back from the enlarged bore to the spark gap to clear from the spark gap hot gases residues generated during the discharge and simultaneously restore the gas density and pressure in the spark gap to its initial value.

  13. Photonic bandgap amorphous chalcogenide thin films with multilayered structure grown by pulsed laser deposition method

    NASA Astrophysics Data System (ADS)

    Zhang, Shao-qian; Němec, Petre; Nazabal, Virginie; Jin, Yu-qi

    2016-05-01

    Amorphous chalcogenide thin films were fabricated by the pulsed laser deposition technique. Thereafter, the stacks of multilayered thin films for reflectors and microcavity were designed for telecommunication wavelength. The prepared multilayered thin films for reflectors show good compatibility. The microcavity structure consists of Ge25Ga5Sb10S65 (doped with Er3+) spacer layer surrounded by two 5-layer As40Se60/Ge25Sb5S70 reflectors. Scanning/transmission electron microscopy results show good periodicity, great adherence and smooth interfaces between the alternating dielectric layers, which confirms a suitable compatibility between different materials. The results demonstrate that the chalcogenides can be used for preparing vertical Bragg reflectors and microcavity with high quality.

  14. Method for pulse control in a laser including a stimulated brillouin scattering mirror system

    DOEpatents

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2007-10-23

    A laser system, such as a master oscillator/power amplifier system, comprises a gain medium and a stimulated Brillouin scattering SBS mirror system. The SBS mirror system includes an in situ filtered SBS medium that comprises a compound having a small negative non-linear index of refraction, such as a perfluoro compound. An SBS relay telescope having a telescope focal point includes a baffle at the telescope focal point which blocks off angle beams. A beam splitter is placed between the SBS mirror system and the SBS relay telescope, directing a fraction of the beam to an alternate beam path for an alignment fiducial. The SBS mirror system has a collimated SBS cell and a focused SBS cell. An adjustable attenuator is placed between the collimated SBS cell and the focused SBS cell, by which pulse width of the reflected beam can be adjusted.

  15. Asymmetric Ultrasonic Pulse Radiation Using Electromagnetic-Induction Transducer and PZT(Pb(Zr-Ti)O3) Transducer with Wave Synthesis Method

    NASA Astrophysics Data System (ADS)

    Endoh, Nobuyuki; Yamamoto, Koji

    1993-05-01

    In medical applications, especially in urology, we use a fragmentation calculus technique with shock waves. This technique is very profitable because of no abdominal surgery for a human being. Large negative sound amplitude pulses, however, can cause problems such as internal hemorrhage or pain in the human body. The final goal of this study is to develop a means to project an intense positive unipolar pulse without negative sound pressure. We improved a composite transducer consisting of an electromagnetic-induction-type (EMI) transducer and PZT (Pb(Zr-Ti)O3) transducers. An EMI transducer consisting of a metal coil and vibration membrane can project intense sound pulses into water. In order to suppress its negative sound pressure, we project a compensation pulse with PZT transducers using an inverse filtering method. An asymmetric pulse whose P+ to P- amplitude ratio was very high was projected in water.

  16. Method of optical self-mixing for pulse wave transit time in comparison with other methods and correlation with blood pressure

    NASA Astrophysics Data System (ADS)

    Meigas, Kalju; Lass, Jaanus; Kattai, Rain; Karai, Deniss; Kaik, Juri

    2004-07-01

    This paper is a part of research to develop convenient method for continuous monitoring of arterial blood pressure by non-invasive and non-oscillometric way. A simple optical method, using self-mixing in a diode laser, is used for detection of skin surface vibrations near the artery. These vibrations, which can reveal the pulsate propagation of blood pressure waves along the vasculature, are used for pulse wave registration. The registration of the Pulse Wave Transit Time (PWTT) is based on computing the time delay in different regions of the human body using an ECG as a reference signal. In this study, the comparison of method of optical self-mixing with other methods as photoplethysmographic (PPG) and bioimpedance (BI) for PWTT is done. Also correlation of PWTT, obtained with different methods, with arterial blood pressure is calculated. In our study, we used a group of volunteers (34 persons) who made the bicycle exercise test. The test consisted of cycling sessions of increasing workloads during which the HR changed from 60 to 180 beats per minute. In addition, a blood pressure (NIBP) was registered with standard sphygmomanometer once per minute during the test and all NIBP measurement values were synchronized to other signals to find exact time moments where the systolic blood pressure was detected (Korotkoff sounds starting point). Computer later interpolated the blood pressure signal in order to get individual value for every heart cycle. The other signals were measured continuously during all tests. At the end of every session, a recovery period was included until person's NIBP and heart rate (HR) normalized. As a result of our study it turned out that time intervals that were calculated from plethysmographic (PPG) waveforms were in the best correlation with systolic blood pressure. The diastolic pressure does not correlate with any of the parameters representing PWTT. The pulse wave signals measured by laser and piezoelectric transducer are very similar

  17. Effect of temperature on O⊘ reactions and equilibria: A pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Elliot, Allen John; McCracken, David Ritchie

    The p Ka of the hydroxyl radical was measured over the 20-80°C temperature range. At 20°C, the p Ka was 11.84 and fell to 10.81 at 80°C. The dissociation constant for the ozonide anion (O⊘ 3⇌O 2+O⊘) was found to be 5.5 × 10 -7 mol dm -3 at 20°C and 46.2 × 10 -7 mol dm -3 at 70°C. The rate constants and activation energies for the reaction of O⊘ and OH with 2-propanol, methanol and 3-hexene-1,6-dicarboxylate ions have also been measured.

  18. Reaction of alcohol radicals with cyclic disulfides. An optical and conductimetric pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Anderson, Robert F.; Vojnovic, Borivoj; Patel, Kantilal B.; Michael, Barry D.

    The disulfides lipoamide (LIPA) and oxidized dithiothreitol ( ox-DTT) react with methanol, ethanol, isopropanol and t-butanol radicals in aqueous solution at pH10.8 to form disulfide radical anions. Electron transfer rates range from ca 10 7 dm 3 mol -1s -1 for t-butanol radicals with LIPA to 3.6 × 10 8 dm 3 mol -1s -1 for methanol radicals with LIPA. The formations of the disulfide radical anions were followed by simultaneously monitoring absorption changes at 400 nm and changes in conductance with time. The electron transfer efficiencies are higher for LIPA than for ox-DTT increasing in the series t-butanol ≪isopropanol

  19. Pulse radiolysis study on electrons trapped in semiclathrates and non-clathrate hydrates

    SciTech Connect

    Zagorski, Z.P.

    1987-02-12

    Trapping of electrons in specific water molecule vacancies, observed previously in crystalline aqueous clathrates, has also been found in semiclathrates (e.g., tetramethylammonium hydroxide pentahydrate), in clathrates showing hydrogen bonds between host and guest molecules (e.g., piperazine clathrate), and also in inorganic hydrates (e.g., sodium carbonate decahydrate). The lifetime of the electron is sometimes longer than in the case of true clathrates; e.g., t/sub 1/2/ = 3.5 ms (first-order decay in piperazine clathrate). The existence of comparatively long-lived electrons at room temperature may be considered a general phenomenon. The condition for its occurrence is the presence of OH/sup -/ or F/sup -/ anion, which can substitute for H/sub 2/O in the aqueous part of the compound and when displaced leaves an electron trap. In other ionic and nonionic compounds, the condition for the trapping of long-lived electrons is protonation of the principal compound, thereby leaving the solution or melt alkaline during the crystallization of the hydrate. Interpretation in terms of preexistent traps invokes the crystal imperfections chemistry, which in the case of hydrates has not yet been noticed. It has been assumed that electrons occupy the vacancies temporarily revealing their presence. In some clathrates and other hydrates, the long-lived electron traps do not occur; instead, the electron shows a similar spectrum (620 nm maximum), decaying by 2-3 orders of magnitude faster than in long-lived traps. It is assumed that this is a case of electron digging its own hole, although an alternative explanation may be through trapping in other kinds of crystal imperfections in the aqueous moiety of the hydrate.

  20. Oxidizing properties of CCl 3O .2 radicals studied by pulse radiolysis

    NASA Astrophysics Data System (ADS)

    Grodkowski, J.; Stuglik, Z.; Czajkowski, W.

    CCl 3O .2 radicals were produced by reactions of solvated electrons with CCl 4 in the presence of O 2 in the solutions. The reducing species e -solv were thus converted into oxidizing radicals. There are presented examples of organic radical-cations production by reactions of appropriate solutes with CCl 3O .2 in methanol and 2-propanol solutions, which are rather typical media for reduction processes.

  1. Are positive ion radicals formed in pulse radiolysis of alkylbenzenesulfonates. [7 MeV linear accelerator

    SciTech Connect

    Behar, D. )

    1991-05-30

    Oxidation of alkylbenzenesulfonates by OH radicals proceeds via two routes: 75-85% of the OH radicals react via addition to the benzene ring, while the rest abstract an H atom from the alkyl group. The relative distribution between the two paths of reaction depends on the nature of the alkyl group. No evidence for the formation of cation radicals from OH adducts was found. H radicals add to the benzene ring to form cyclohexadienyl type radicals, but when reacted with isopropylbenzenesulfonate about 15% of the H radicals abstract hydrogen from the alkyl to form the benzyl type radical. The reaction of SO{sub 4}{sup {sm bullet}{minus}} with alkylbenzenesulfonates produces 50-70% OH adducts and the rest are the benzyl type radicals. At high concentrations of solute and persulfate a short-lived precursor to the benzyl radicals has been observed. The precursors observed with p-toluenesulfonate, isopropylbenzenesulfonate, and m-toluenesulfonate decay in a first-order process with the rates 1.4 {times} 10{sup 6}, 9.4 {times} 10{sup 5}, and 2.5 {times} 10{sup 5} s{sup {minus}1}, respectively. The short-lived precursor is identified as an unstable OH adduct to the benzene ring.

  2. Pulse radiolytic studies of electron transfer processes and applications to solar photochemistry. Progress report, [March 1992--March 1993

    SciTech Connect

    Neta, P.

    1993-04-01

    Electron transfer and other reactions of various short-lived intermediates have been studied by pulse radiolysis and laser flash photolysis. Highlights of results during the past year are summarized under two main sections: Metalloporphyrin electron transfer and associated reactions, and solvent effects on reactions of inorganic radicals and organic peroxyl radicals.

  3. Time-resolved flowmetering of gas-liquid two-phase pipe flow by ultrasound pulse Doppler method

    NASA Astrophysics Data System (ADS)

    Murai, Yuichi; Tasaka, Yuji; Takeda, Yasushi

    2012-03-01

    Ultrasound pulse Doppler method is applied for componential volumetric flow rate measurement in multiphase pipe flow consisted of gas and liquid phases. The flowmetering is realized with integration of measured velocity profile over the cross section of the pipe within liquid phase. Spatio-temporal position of interface is detected also with the same ultrasound pulse, which further gives cross sectional void fraction. A series of experimental demonstration was shown by applying this principle of measurement to air-water two-phase flow in a horizontal tube of 40 mm in diameter, of which void fraction ranges from 0 to 90% at superficial velocity from 0 to 15 m/s. The measurement accuracy is verified with a volumetric type flowmeter. We also analyze the accuracy of area integration of liquid velocity distribution for many different patterns of ultrasound measurement lines assigned on the cross section of the tube. The present method is also identified to be pulsation sensor of flow rate that fluctuates with complex gas-liquid interface behavior.

  4. Time-resolved resonant photoionization of He using a time-dependent Feshbach method with ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Granados-Castro, C. M.; Sanz-Vicario, J. L.

    2013-03-01

    We study the photoionization and autoionization of the helium atom subject to ultrashort laser pulses by using a Feshbach formalism in the time domain. We solve the time-dependent Schrödinger equation in terms of a configuration interaction (CI) spectral method, in which the total wavefunction is expanded with configurations defined within bound-like ( {Q}) and scattering-like ( {P}) halfspaces. The method allows one to provide accurate descriptions of both the atomic structure (energy positions and widths) and the photodynamics. We illustrate our approach by (i) calculating the time-resolved one-photon ionization below the He+ (n = 2) ionization threshold, from 11Se and 21Po initial states, then reaching the lowest autoionizing states of 1Se, 1Po and 1De final symmetries, (ii) studying the temporal formation of the Fano profile of 1Po resonances and (iii) showing its performance in obtaining the perturbative long-time limit of one- and two-photon ionization cross sections using ultrashort laser pulses following a recently developed procedure in Palacios et al (2008 Phys. Rev. A 77 032716).

  5. Shift-invariant, DWT-based "projection" method for estimation of ultrasound pulse power spectrum.

    PubMed

    Michailovich, Oleg; Adam, Dan

    2002-08-01

    An approach to computing estimates of the ultrasound pulse spectrum from echo-ultrasound RF sequences, measured from biological tissues, is proposed. It is computed by a "projection" algorithm based on the Discrete Wavelet Transform (DWT) using averaging over a range of linear shifts. It is shown that the robust, shift invariant estimate of the ultrasound pulse power spectrum can be obtained by the projection of RF line log spectrum on an appropriately chosen subspace of L2(R) (i.e., the space of square-integrable functions) that is spanned by a redundant collection of compactly supported, scaling functions. This redundant set is formed from the traditional (in Wavelet analysis) orthogonal set of scaling functions and also by all its linear (discrete) shifts. A proof is given that the estimate, so obtained, could be viewed as the average of the orthogonal projections of the RF line log spectrum, computed for all significant linear shifts of the RF line log spectrum in frequency domain. It implies that the estimate is shift-invariant. A computationally efficient scheme is presented for calculating the estimate. Proof is given that the averaged, shift-invariant estimate can be obtained simply by a convolution with a kernel, which can be viewed as the discretized auto-correlation function of the scaling function, appropriate to the particular subspace being considered. It implies that the computational burden is at most O(n log2 n), where n is the problem size, making the estimate quite suitable for real-time processing. Because of the property of the wavelet transform to suppress polynomials of orders lower than the number of the vanishing moments of the wavelet used, the presented approach can be considered as a local polynomial fitting. This locality plays a crucial role in the performance of the algorithm, improving the robustness of the estimation. Moreover, it is shown that the "averaging" nature of the proposed estimation allows using (relatively) poorly

  6. An extended field method solution for a pulse loaded thin plate

    NASA Technical Reports Server (NTRS)

    Donaldson, B. K.; Starkey, N. B.

    1980-01-01

    This paper deals with a new extension of a weighted residual method of analysis called the extended field method. The extended field method is applied for the first time to the problem of the transient vibration of a uniformly thin elastic plate. Numerical results have been obtained which validate the analysis procedure and show better solution convergence than is obtainable by standard methods of analysis for the same number of degrees of freedom. Further studies are necessary to obtain still better convergence.

  7. Study of the shower maximum depth by the method of detection of the EAS Cerenkov light pulse shape

    NASA Technical Reports Server (NTRS)

    Aliev, N.; Kakhkharov, M.; Khakimov, N.; Makhmudov, B. M.; Rakhimova, N.; Tashpulatov, R.; Khristiansen, G. B.; Prosin, V. V.; Alimov, T.; Zhukov, V. Y.

    1985-01-01

    The results of processing the data on the shape of the EAS Cerenkov light pulses recorded by the extensive air showers (EAS) array are presented. The pulse FWHM is used to find the mean depth of EAS maximum.

  8. High-speed camera analysis for nanoparticles produced by using a pulsed wire-discharge method

    NASA Astrophysics Data System (ADS)

    Kim, Jong Hwan; Kim, Dae Sung; Ryu, Bong Ki; Suematsu, Hisayuki; Tanaka, Kenta

    2016-07-01

    We investigated the performance of a high-speed camera and the nanoparticle size distribution to quantify the mechanism of synthesized nanoparticle formation in a pulsed wire discharge (PWD) experiment. The Sn-58Bi alloy wire was 0.5 mm in diameter and 32 mm long; it was prepared in the PWD chamber, and the evaporation explosion process was observed by using a high-speed camera. In order to vary the conditions and analyze the mechanisms of nanoparticle synthesis in the PWD, we changed the pressure of the N2 gas in the chamber from 25 to 75 kPa. To synthesize nanoparticles on a nano-scale, we fixed the charging voltage at 6 kV, and the high-speed camera captured pictures at 22,500 frames per second. The experimental results show that the electronic explosion process at different N2 gas pressures can be characterized by using the explosion's duration and the explosion's intensity. The experiments at the lowest pressure exhibited a longer explosion duration and a greater intensity. Also, at low pressure, very small nanoparticles with a good dispersion were produced.

  9. Epitaxial composition-graded perovskite films grown by a dual-beam pulsed laser deposition method

    NASA Astrophysics Data System (ADS)

    Sakai, Joe; Autret-Lambert, Cécile; Sauvage, Thierry; Courtois, Blandine; Wolfman, Jérôme; Gervais, François

    2013-10-01

    We prepared SrTiO3 (STO) to Ba0.6Sr0.4TiO3 (BST06) out-of-plane composition-graded films on STO (100) substrates by means of a dual-beam dual-target pulsed laser deposition technique. In the deposition system, a sliding mirror divides one KrF excimer laser beam into two, realizing the dual-beam of controlled intensity ratio. X-ray diffraction reciprocal space mapping has revealed that the graded films deposited under oxygen pressure at or lower than 1×10-3 mbar were coherently strained with the same in-plane lattice parameter as the substrate. Their composition gradient along the growth direction was confirmed by Rutherford backscattering analysis to be uniform. We deposited BST06 top layers of various thickness on epitaxial composition-graded (ECG) buffer layers and examined their coherency and crystallinity. In comparison with the cases of STO homoepitaxial buffer layers, ECG buffer layers achieved better crystallinity of top BST06 layers, suggesting that the crystallinity of a heteroepitaxially-grown film is affected not only by the in-plane lattice matching but also by the out-of-plane lattice continuity with the substrate. ECG films that bridge compositions of substrate and top layer materials can be useful buffer layers for epitaxial growth of lattice-mismatched oxide films.

  10. Method for wavelength stabilization of pulsed difference frequency laser at 1572 nm for CO(2) detection lidar.

    PubMed

    Gong, Wei; Ma, Xin; Han, Ge; Xiang, Chengzhi; Liang, Ailin; Fu, Weidong

    2015-03-01

    High-accuracy on-line wavelength stabilization is required for differential absorption lidar (DIAL), which is ideal for precisely measuring atmospheric CO(2) concentration. Using a difference-frequency laser, we developed a ground-based 1.57-μm pulsed DIAL for performing atmospheric CO(2) measurements. Owing to the system complexity, lacking phase, and intensity instability, the stabilization method was divided into two parts-wavelength calibration and locking-based on saturated absorption. After obtaining the on-line laser position, accuracy verification using statistical theory and locking stabilization using a one-dimensional template matching method, namely least-squares matching (LSM), were adopted to achieve wavelength locking. The resulting system is capable of generating a stable wavelength. PMID:25836838

  11. Study of vesicle size distribution dependence on pH value based on nanopore resistive pulse method

    NASA Astrophysics Data System (ADS)

    Lin, Yuqing; Rudzevich, Yauheni; Wearne, Adam; Lumpkin, Daniel; Morales, Joselyn; Nemec, Kathleen; Tatulian, Suren; Lupan, Oleg; Chow, Lee

    2013-03-01

    Vesicles are low-micron to sub-micron spheres formed by a lipid bilayer shell and serve as potential vehicles for drug delivery. The size of vesicle is proposed to be one of the instrumental variables affecting delivery efficiency since the size is correlated to factors like circulation and residence time in blood, the rate for cell endocytosis, and efficiency in cell targeting. In this work, we demonstrate accessible and reliable detection and size distribution measurement employing a glass nanopore device based on the resistive pulse method. This novel method enables us to investigate the size distribution dependence of pH difference across the membrane of vesicles with very small sample volume and rapid speed. This provides useful information for optimizing the efficiency of drug delivery in a pH sensitive environment.

  12. The new methods of treatment for age-related macular degeneration using the ultra-short pulsed laser

    NASA Astrophysics Data System (ADS)

    Iwamoto, Yumiko; Awazu, Kunio; Suzuki, Sachiko; Ohshima, Tetsuro; Sawa, Miki; Sakaguchi, Hirokazu; Tano, Yasuo; Ohji, Masahito

    2007-02-01

    The non-invasive methods of treatments have been studying for the improvement of quality of life (QOL) of patients undergoing treatment. A photodynamic therapy (PDT) is one of the non-invasive treatments. PDT is the methods of treatment using combination of a laser and a photosensitizer. PDT has few risks for patients. Furthermore, PDT enables function preservation of a disease part. PDT has been used for early cancer till now, but in late years it is applied for age-related macular degeneration (AMD). AMD is one of the causes of vision loss in older people. However, PDT for AMD does not produce the best improvement in visual acuity. The skin photosensivity by an absorption characteristic of a photosensitizer is avoided. We examined new PDT using combination of an ultra-short pulsed laser and indocyanine green (ICG).

  13. Characterization of perovskite film prepared by pulsed laser deposition on ferritic stainless steel using microscopic and optical methods

    NASA Astrophysics Data System (ADS)

    Durda, E.; Jaglarz, J.; Kąc, S.; Przybylski, K.; El Kouari, Y.

    2016-06-01

    The perovskite La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF48) film was deposited on Crofer 22 APU ferritic stainless steel by pulsed laser deposition (PLD). Morphological studies of the sample were performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Information about film thickness and surface topography of the film and the steel substrate were obtained using following optical methods: spectroscopic ellipsometry (SE), bidirectional reflection distribution function (BRDF) and total integrated reflectometry (TIS). In particular, the BRDF study, being complementary to atomic force microscopy, yielded information about surface topography. Using the previously mentioned methods, the following statistic surface parameters were determined: root-mean square (rms) roughness and autocorrelation length by determining the power spectral density (PSD) function of surface irregularities.

  14. Long pulse production from short pulses

    DOEpatents

    Toeppen, J.S.

    1994-08-02

    A method of producing a long output pulse from a short pump pulse is disclosed, using an elongated amplified fiber having a doped core that provides an amplifying medium for light of one color when driven into an excited state by light of a shorter wavelength and a surrounding cladding. A seed beam of the longer wavelength is injected into the core at one end of the fiber and a pump pulse of the shorter wavelength is injected into the cladding at the other end of the fiber. The counter-propagating seed beam and pump pulse will produce an amplified output pulse having a time duration equal to twice the transit time of the pump pulse through the fiber plus the length of the pump pulse. 3 figs.

  15. Long pulse production from short pulses

    DOEpatents

    Toeppen, John S.

    1994-01-01

    A method of producing a long output pulse (SA) from a short pump pulse (P), using an elongated amplified fiber (11) having a doped core (12) that provides an amplifying medium for light of one color when driven into an excited state by light of a shorter wavelength and a surrounding cladding 13. A seed beam (S) of the longer wavelength is injected into the core (12) at one end of the fiber (11) and a pump pulse (P) of the shorter wavelength is injected into the cladding (13) at the other end of the fiber (11). The counter-propagating seed beam (S) and pump pulse (P) will produce an amplified output pulse (SA) having a time duration equal to twice the transit time of the pump pulse (P) through the fiber (11) plus the length of the pump pulse (P).

  16. Pulse Wave Velocity and Cardiac Output vs. Heart Rate in Patients with an Implanted Pacemaker Based on Electric Impedance Method Measurement

    NASA Astrophysics Data System (ADS)

    Soukup, Ladislav; Vondra, Vlastimil; Viščor, Ivo; Jurák, Pavel; Halámek, Josef

    2013-04-01

    The methods and device for estimation of cardiac output and measurement of pulse wave velocity simultaneously is presented here. The beat-to-beat cardiac output as well as pulse wave velocity measurement is based on application of electrical impedance method on the thorax and calf. The results are demonstrated in a study of 24 subjects. The dependence of pulse wave velocity and cardiac output on heart rate during rest in patients with an implanted pacemaker was evaluated. The heart rate was changed by pacemaker programming while neither exercise nor drugs were applied. The most important result is that the pulse wave velocity, cardiac output and blood pressure do not depend significantly on heart rate, while the stroke volume is reciprocal proportionally to the heart rate.

  17. A modified evaluation method to reduce finite pulse time effects in flash diffusivity measurement

    NASA Astrophysics Data System (ADS)

    Tao, Ye; Yang, Liping; Zhong, Qiu; Xu, Zijun; Luo, Caiyun

    2015-12-01

    A modified evaluation method for laser flash is proposed. In this method, the moment of laser-heating cutoff time is considered as zero point. The penetration depth and formula equation of the sample temperature distribution are obtained with the approximate analytical solution before time zero (during laser heating) for the physical model of a continuously heated half-infinite, well-distributed sample. The weighted-average and approximate-equation methods are then used to quantitatively determine the laser effect depth, which leads to the formulation of a modified evaluation method in flash thermal diffusivity measurement. Results of the simulation calculations and experiments confirm the correctness of the modified method, which remarkably increases flash method applications. The modified method is applicable only to cases in which δ(x) does not exceed the sample thickness ( √{ 12 α τ 0 } ≤ L ) during laser heating.

  18. A modified evaluation method to reduce finite pulse time effects in flash diffusivity measurement.

    PubMed

    Tao, Ye; Yang, Liping; Zhong, Qiu; Xu, Zijun; Luo, Caiyun

    2015-12-01

    A modified evaluation method for laser flash is proposed. In this method, the moment of laser-heating cutoff time is considered as zero point. The penetration depth and formula equation of the sample temperature distribution are obtained with the approximate analytical solution before time zero (during laser heating) for the physical model of a continuously heated half-infinite, well-distributed sample. The weighted-average and approximate-equation methods are then used to quantitatively determine the laser effect depth, which leads to the formulation of a modified evaluation method in flash thermal diffusivity measurement. Results of the simulation calculations and experiments confirm the correctness of the modified method, which remarkably increases flash method applications. The modified method is applicable only to cases in which δ(x) does not exceed the sample thickness (√(12ατ0)≤L) during laser heating. PMID:26724057

  19. Brachial-Ankle Pulse Wave Velocity: Background, Method, and Clinical Evidence

    PubMed Central

    Munakata, Masanori

    2016-01-01

    Background The populations of many developed countries are becoming progressively older. In aged societies, assessment of total vascular risk is critically important, because old age is usually associated with multiple risks. In this regard, pulse wave velocity (PWV) could be a global cardiovascular marker, since it increases with advancing age, high blood pressure, hyperglycaemia, and other traditional risks, summating cardiovascular risks. Carotid-femoral PWV has been widely applied in Western countries and has been used as a gold-standard PWV measure. However, this measure has never been implemented by general practitioners in Japan, possibly because of methodological difficulties. The life expectancy of Japanese people is now the highest in the world, and the establishment of an adequate total vascular risk measure is an urgent need. Against this background, brachial-ankle PWV was developed at the beginning of this century. Summary Measurement of this parameter is easy, and its reproducibility is good. Moreover, the generality of the methodology is guaranteed. Brachial-ankle PWV has been reported to consistently increase with most traditional cardiovascular risk factors except dyslipidaemia. A meta-analysis of cohort studies including various levels of risk has shown that a 1 m/s increase in brachial-ankle PWV is associated with a 12% increase in the risk of cardiovascular events. Moreover, simultaneous evaluation of the ankle-brachial index could allow further risk stratification of high-risk individuals, who are common in aged societies. This unique feature is indispensable for the management of aged populations, who usually are exposed to multiple risks and have polyvascular diseases. This evidence, however, is chiefly derived from East Asian countries. The collection of data from Caucasian populations, therefore, remains a task for the future. Key Message Brachial-ankle PWV has the potential to become a measure of arterial stiffness worldwide. PMID:27195241

  20. Water accessibility in a membrane-inserting peptide comparing Overhauser DNP and pulse EPR methods

    NASA Astrophysics Data System (ADS)

    Segawa, Takuya F.; Doppelbauer, Maximilian; Garbuio, Luca; Doll, Andrin; Polyhach, Yevhen O.; Jeschke, Gunnar

    2016-05-01

    Water accessibility is a key parameter for the understanding of the structure of biomolecules, especially membrane proteins. Several experimental techniques based on the combination of electron paramagnetic resonance (EPR) spectroscopy with site-directed spin labeling are currently available. Among those, we compare relaxation time measurements and electron spin echo envelope modulation (ESEEM) experiments using pulse EPR with Overhauser dynamic nuclear polarization (DNP) at X-band frequency and a magnetic field of 0.33 T. Overhauser DNP transfers the electron spin polarization to nuclear spins via cross-relaxation. The change in the intensity of the 1H NMR spectrum of H2O at a Larmor frequency of 14 MHz under a continuous-wave microwave irradiation of the nitroxide spin label contains information on the water accessibility of the labeled site. As a model system for a membrane protein, we use the hydrophobic α-helical peptide WALP23 in unilamellar liposomes of DOPC. Water accessibility measurements with all techniques are conducted for eight peptides with different spin label positions and low radical concentrations (10-20 μM). Consistently in all experiments, the water accessibility appears to be very low, even for labels positioned near the end of the helix. The best profile is obtained by Overhauser DNP, which is the only technique that succeeds in discriminating neighboring positions in WALP23. Since the concentration of the spin-labeled peptides varied, we normalized the DNP parameter ɛ, being the relative change of the NMR intensity, by the electron spin concentration, which was determined from a continuous-wave EPR spectrum.

  1. Robust, Efficient, and Practical Electrogene Transfer Method for Human Mesenchymal Stem Cells Using Square Electric Pulses

    PubMed Central

    Liew, Aaron; Lesueur, Léa L.; De Ménorval, Marie-Amélie; O'Brien, Timothy; Mir, Lluis M.

    2013-01-01

    Abstract Mesenchymal stem cells (MSCs) are multipotent nonhematopoietic cells with the ability to differentiate into various specific cell types, thus holding great promise for regenerative medicine. Early clinical trials have proven that MSC-based therapy is safe, with possible efficacy in various diseased states. Moreover, genetic modification of MSCs to improve their function can be safely achieved using electrogene transfer. We previously achieved transfection efficiencies of up to 32% with preserved viability in rat MSCs. In this study, we further improved the transfection efficiency and transgene expression in human MSCs (hMSCs), while preserving the cells viability and ability to differentiate into osteoblasts and adipocytes by increasing the plasmid concentration and altering the osmotic pressure of the electrotransfer buffer. Using a square-wave electric pulse generator, we achieved a transfection efficiency of more than 80%, with around 70% viability and a detectable transgene expression of up to 30 days. Moreover, we demonstrated that this transfection efficiency can be reproduced reliably on two different sources of hMSCs: the bone marrow and adipose tissue. We also showed that there was no significant donor variability in terms of their transfection efficiency and viability. The cell confluency before electrotransfer had no significant effect on the transfection efficiency and viability. Cryopreservation of transfected cells maintained their transgene expression and viability upon thawing. In summary, we are reporting a robust, safe, and efficient protocol of electrotransfer for hMSCs with several practical suggestions for an optimal use of genetically engineered hMSCs for clinical application. PMID:23931158

  2. Water accessibility in a membrane-inserting peptide comparing Overhauser DNP and pulse EPR methods.

    PubMed

    Segawa, Takuya F; Doppelbauer, Maximilian; Garbuio, Luca; Doll, Andrin; Polyhach, Yevhen O; Jeschke, Gunnar

    2016-05-21

    Water accessibility is a key parameter for the understanding of the structure of biomolecules, especially membrane proteins. Several experimental techniques based on the combination of electron paramagnetic resonance (EPR) spectroscopy with site-directed spin labeling are currently available. Among those, we compare relaxation time measurements and electron spin echo envelope modulation (ESEEM) experiments using pulse EPR with Overhauser dynamic nuclear polarization (DNP) at X-band frequency and a magnetic field of 0.33 T. Overhauser DNP transfers the electron spin polarization to nuclear spins via cross-relaxation. The change in the intensity of the (1)H NMR spectrum of H2O at a Larmor frequency of 14 MHz under a continuous-wave microwave irradiation of the nitroxide spin label contains information on the water accessibility of the labeled site. As a model system for a membrane protein, we use the hydrophobic α-helical peptide WALP23 in unilamellar liposomes of DOPC. Water accessibility measurements with all techniques are conducted for eight peptides with different spin label positions and low radical concentrations (10-20 μM). Consistently in all experiments, the water accessibility appears to be very low, even for labels positioned near the end of the helix. The best profile is obtained by Overhauser DNP, which is the only technique that succeeds in discriminating neighboring positions in WALP23. Since the concentration of the spin-labeled peptides varied, we normalized the DNP parameter ϵ, being the relative change of the NMR intensity, by the electron spin concentration, which was determined from a continuous-wave EPR spectrum. PMID:27208942

  3. Modelling NDE pulse-echo inspection of misorientated planar rough defects using an elastic finite element method

    NASA Astrophysics Data System (ADS)

    Pettit, J. R.; Walker, A. E.; Lowe, M. J. S.

    2015-03-01

    Pulse-echo ultrasonic NDE examination of large pressure vessel forgings is a design and construction code requirement in the power generation industry. Such inspections aim to size and characterise potential defects that may have formed during the forging process. Typically these defects have a range of orientations and surface roughnesses which can greatly affect ultrasonic wave scattering behaviour. Ultrasonic modelling techniques can provide insight into defect response and therefore aid in characterisation. However, analytical approaches to solving these scattering problems can become inaccurate, especially when applied to increasingly complex defect geometries. To overcome these limitations a elastic Finite Element (FE) method has been developed to simulate pulse-echo inspections of embedded planar defects. The FE model comprises a significantly reduced spatial domain allowing for a Monte-Carlo based approach to consider multiple realisations of defect orientation and surface roughness. The results confirm that defects aligned perpendicular to the path of beam propagation attenuate ultrasonic signals according to the level of surface roughness. However, for defects orientated away from this plane, surface roughness can increase the magnitude of the scattered component propagating back along the path of the incident beam. This study therefore highlights instances where defect roughness increases the magnitude of ultrasonic scattered signals, as opposed to attenuation which is more often assumed.

  4. Modelling NDE pulse-echo inspection of misorientated planar rough defects using an elastic finite element method

    SciTech Connect

    Pettit, J. R.; Lowe, M. J. S.; Walker, A. E.

    2015-03-31

    Pulse-echo ultrasonic NDE examination of large pressure vessel forgings is a design and construction code requirement in the power generation industry. Such inspections aim to size and characterise potential defects that may have formed during the forging process. Typically these defects have a range of orientations and surface roughnesses which can greatly affect ultrasonic wave scattering behaviour. Ultrasonic modelling techniques can provide insight into defect response and therefore aid in characterisation. However, analytical approaches to solving these scattering problems can become inaccurate, especially when applied to increasingly complex defect geometries. To overcome these limitations a elastic Finite Element (FE) method has been developed to simulate pulse-echo inspections of embedded planar defects. The FE model comprises a significantly reduced spatial domain allowing for a Monte-Carlo based approach to consider multiple realisations of defect orientation and surface roughness. The results confirm that defects aligned perpendicular to the path of beam propagation attenuate ultrasonic signals according to the level of surface roughness. However, for defects orientated away from this plane, surface roughness can increase the magnitude of the scattered component propagating back along the path of the incident beam. This study therefore highlights instances where defect roughness increases the magnitude of ultrasonic scattered signals, as opposed to attenuation which is more often assumed.

  5. Nanopore formation on the surface oxide of commercially pure titanium grade 4 using a pulsed anodization method in sulfuric acid.

    PubMed

    Williamson, R S; Disegi, J; Griggs, J A; Roach, M D

    2013-10-01

    Titanium and its alloys form a thin amorphous protective surface oxide when exposed to an oxygen environment. The properties of this oxide layer are thought to be responsible for titanium and its alloys biocompatibility, chemical inertness, and corrosion resistance. Surface oxide crystallinity and pore size are regarded to be two of the more important properties in establishing successful osseointegration. Anodization is an electrochemical method of surface modification used for colorization marking and improved bioactivity on orthopedic and dental titanium implants. Research on titanium anodization using sulphuric acid has been reported in the literature as being primarily conducted in molarity levels 3 M and less using either galvanostatic or potentiostatic methods. A wide range of pore diameters ranging from a few nanometers up to 10 μm have been shown to form in sulfuric acid electrolytes using the potentiostatic and galvanostatic methods. Nano sized pores have been shown to be beneficial for bone cell attachment and proliferation. The purpose of the present research was to investigate oxide crystallinity and pore formation during titanium anodization using a pulsed DC waveform in a series of sulfuric acid electrolytes ranging from 0.5 to 12 M. Anodizing titanium in increasing sulfuric acid molarities showed a trend of increasing transformations of the amorphous natural forming oxide to the crystalline phases of anatase and rutile. The pulsed DC waveform was shown to produce pores with a size range from ≤0.01 to 1 μm(2). The pore size distributions produced may be beneficial for bone cell attachment and proliferation. PMID:23807314

  6. Application of the pulsed fast/thermal neutron method for soil elemental analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil science is a research field where physic concepts and experimental methods are widely used, particularly in agro-chemistry and soil elemental analysis. Different methods of analysis are currently available. The evolution of nuclear physics (methodology and instrumentation) combined with the ava...

  7. Optimized split-step method for modeling nonlinear pulse propagation in fiber Bragg gratings

    SciTech Connect

    Toroker, Zeev; Horowitz, Moshe

    2008-03-15

    We present an optimized split-step method for solving nonlinear coupled-mode equations that model wave propagation in nonlinear fiber Bragg gratings. By separately controlling the spatial and the temporal step size of the solution, we could significantly decrease the run time duration without significantly affecting the result accuracy. The accuracy of the method and the dependence of the error on the algorithm parameters are studied in several examples. Physical considerations are given to determine the required resolution.

  8. Studies in electron phenomena in MOS structures: The pulsed C-V method. M.S. Thesis. Abstract Only

    NASA Technical Reports Server (NTRS)

    Kaplan, G.

    1983-01-01

    The pulse hysteresis capacitance voltage (C-V) provides a straight forward technique for measuring the change of various charges in MOS structures and a tool for investigating the kinetics of various electron phenomena is developed and described. The method can be used for measuring the energy distribution and kinetics of surface states with the resolution of about 1/5 x 10 to the -9 power cm eV. Some transients in an MOS structure, particularly, the thermal generation of minority charge carriers via surface states and the relaxation of minority charge carriers supplied from the inversion layer outside the MOS structure are theoretically investigated. Analytical expressions which clearly present the physics of those electron phenomena are derived.

  9. Paired Pulse Basis Functions for the Method of Moments EFIE Solution of Electromagnetic Problems Involving Arbitrarily-shaped, Three-dimensional Dielectric Scatterers

    NASA Technical Reports Server (NTRS)

    MacKenzie, Anne I.; Rao, Sadasiva M.; Baginski, Michael E.

    2007-01-01

    A pair of basis functions is presented for the surface integral, method of moment solution of scattering by arbitrarily-shaped, three-dimensional dielectric bodies. Equivalent surface currents are represented by orthogonal unit pulse vectors in conjunction with triangular patch modeling. The electric field integral equation is employed with closed geometries for dielectric bodies; the method may also be applied to conductors. Radar cross section results are shown for dielectric bodies having canonical spherical, cylindrical, and cubic shapes. Pulse basis function results are compared to results by other methods.

  10. Comparative Study of Two Methods of Orthogonal Double-Pulse Laser-Induced Breakdown Spectroscopy of Aluminum

    NASA Astrophysics Data System (ADS)

    Safi, A.; Bahreini, M.; Tavassoli, S. H.

    2016-03-01

    Double-pulse laser induced breakdown spectroscopy (DP-LIBS) of aluminum sample is studied experimentally in orthogonal configuration in air. In this configuration, two schemes of reheating and pre-ablation are examined and the results are compared with single pulse one. The effect of delay time between two laser pulses on emission line intensities of plasma is investigated. Some of the parameters that have been involved in different mechanism of signal enhancement such as plasma temperature, sample heating effects, atmospheric effects, and modification of the ablation dynamics are more discussed. Investigation of the effect of laser pulse energy on emission line intensities in single pulse LIBS experiment demonstrate that because of saturation effects the intensities will not increase necessarily by increasing the laser pulse energy. Moreover, the results show that the electron temperature and rate of mass removal in orthogonal configuration of DP-LIBS is higher than that of single pulse with the same total energy. It is suggested that for correct comparison between single and double pulse results, the optimum pulse energy in single pulse should be considered. Overall, our results demonstrate that under optimized conditions the signal enhancement is much more in pre-ablation configuration than re-heating configuration.

  11. Method of using deuterium-cluster foils for an intense pulsed neutron source

    DOEpatents

    Miley, George H.; Yang, Xiaoling

    2013-09-03

    A method is provided for producing neutrons, comprising: providing a converter foil comprising deuterium clusters; focusing a laser on the foil with power and energy sufficient to cause deuteron ions to separate from the foil; and striking a surface of a target with the deuteron ions from the converter foil with energy sufficient to cause neutron production by a reaction selected from the group consisting of D-D fusion, D-T fusion, D-metal nuclear spallation, and p-metal. A further method is provided for assembling a plurality of target assemblies for a target injector to be used in the previously mentioned manner. A further method is provided for producing neutrons, comprising: splitting a laser beam into a first beam and a second beam; striking a first surface of a target with the first beam, and an opposite second surface of the target with the second beam with energy sufficient to cause neutron production.

  12. Remote sensing image fusion method in CIELab color space using nonsubsampled shearlet transform and pulse coupled neural networks

    NASA Astrophysics Data System (ADS)

    Jin, Xin; Zhou, Dongming; Yao, Shaowen; Nie, Rencan; Yu, Chuanbo; Ding, Tingting

    2016-04-01

    In CIELab color space, we propose a remote sensing image fusion technique based on nonsubsampled shearlet transform (NSST) and pulse coupled neural network (PCNN), which aim to improve the efficiency and performance of the remote sensing image fusion by combining the excellent properties of the two methods. First, panchromatic (PAN) and multispectral (MS) are transformed into CIELab color space to get different color components. Second, PAN and L component of MS are decomposed by the NSST to obtain corresponding the low-frequency coefficients and high-frequency coefficients. Third, the low-frequency coefficients are fused by intersecting cortical model (ICM); the high-frequency coefficients are divided into several sub-blocks to calculate the average gradient (AG), and the linking strength β of PCNN model is determined by the AG, so that the parameters β can be adaptively set according to the quality of the sub-block images, then the sub-blocks image are input into PCNN to get the oscillation frequency graph (OFG), the method can get the fused high-frequency coefficients according to the OFG. Finally, the fused L component is obtained by inverse NSST, and the fused RGB color image is obtained through inverse CIELab transform. The experimental results demonstrate that the proposed method provide better effect compared with other common methods.

  13. Pulsed microwave heating method for preparation of dye-sensitized solar cells for greener, faster, cheaper production of photovoltaic materials

    NASA Astrophysics Data System (ADS)

    Murphy, Clifford B.; Cotta, Robert; Blais, Timothy; Hall, Charles B.

    2015-05-01

    Microwave heating methods are very popular for developing chemical syntheses that are achieved much more rapidly or with less solvent than via conventional heating methods. Their application to solar cell development has been primarily in developing improvements in the synthesis of dyes and curing of polymer substrates, but not in assisting the photoanode construction of dye-sensitized solar cells. Microwave heating of conducting substrates can lead to arcing of electricity in the reactor, which in turn, can lead to extensive degradation or complete destruction of the photoanode. Here we present our work in applying a pulsed microwave heating method that affords quicker dye deposition times in comparison to conventional heating (μw 40 min, conventional 60 min) with similar dye concentrations as characterized by UV-Vis absorbance, contact angle measurements, and cyclic voltammetry. Our photoanodes are constructed with anatase TiO2 cured onto FTO glass, and deposition of the N719 ruthenium dye either directly to the TiO2 layer or through amide bond formation to a silane layer that has been deposited on the TiO2 layer. Modest improvements in the solar energy conversion efficiency are shown through the microwave method in comparison to conventional heating (μw 0.78% vs. conventional 0.25% reported by K. Szpakolski, et. Al. Polyhedron, 2013, 52, 719-732.)

  14. Digital pulse shape discrimination methods for n-γ separation in an EJ-301 liquid scintillation detector

    NASA Astrophysics Data System (ADS)

    Wan, Bo; Zhang, Xue-Ying; Chen, Liang; Ge, Hong-Lin; Ma, Fei; Zhang, Hong-Bin; Ju, Yong-Qin; Zhang, Yan-Bin; Li, Yan-Yan; Xu, Xiao-Wei

    2015-11-01

    A digital pulse shape discrimination system based on a programmable module NI-5772 has been established and tested with an EJ-301 liquid scintillation detector. The module was operated by running programs developed in LabVIEW, with a sampling frequency up to 1.6 GS/s. Standard gamma sources 22Na, 137Cs and 60Co were used to calibrate the EJ-301 liquid scintillation detector, and the gamma response function was obtained. Digital algorithms for the charge comparison method and zero-crossing method have been developed. The experimental results show that both digital signal processing (DSP) algorithms can discriminate neutrons from γ-rays. Moreover, the zero-crossing method shows better n-γ discrimination at 80 keVee and lower, whereas the charge comparison method gives better results at higher thresholds. In addition, the figure-of-merit (FOM) for detectors of two different dimensions were extracted at 9 energy thresholds, and it was found that the smaller detector presented better n-γ separation for fission neutrons. Supported by National Natural Science Foundation of China (91226107, 11305229) and the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA03030300)

  15. A two-pulse, pump-probe method for short-range, remote standoff detection of chemical warfare agents

    NASA Astrophysics Data System (ADS)

    Bisson, Scott E.; Headrick, Jeffrey M.; Reichardt, Thomas A.; Farrow, Roger L.; Kulp, Thomas J.

    2011-05-01

    We describe a photofragment laser-induced fluorescence (PF-LIF) method that can be applied to the short-range-standoff detection of low-volatility organophosphonate chemical warfare agents (OP-CWAs) on surfaces. It operates by photofragmenting a surface-bound analyte and then actively interrogating a released phosphorous monoxide (PO) fragment using LIF. We demonstrate a single-pulse-pair (pump = 500 μJ @ 266 nm; probe = 20 μJ @ 248 nm) surface detection sensitivity of 30 μg/cm2 for the organophosphonate diisopropyl isothiocyanate phosphonate (DIPP) on aluminum and 210 μg/cm2 for the same analyte on a more porous concrete surface. By detecting the PO photofragment, the method indicates the presence of organophosphonates; however, we show that it also responds to other phosphorouscontaining compounds. Because of its limited specificity, we believe that the method may have most immediate use as a mapping tool to rapidly identify "hotspots" of OP-CWAs. These would then be confirmed using a more specific tool. As one method of confirming the presence of OP-CWAs (and identifying the agent), we demonstrate that the probe beam can be used to acquire Raman-scattering spectra of the target area.

  16. A pilot study comparison of a new method for aortic pulse wave velocity measurements using transthoracic bioimpedance and thigh cuff oscillometry with the standard tonometric method.

    PubMed

    Brinkmann, Julia; Jordan, Jens; Tank, Jens

    2015-04-01

    Aortic pulse wave velocity (aPWV) can be measured with different methodologies, including applanation tonometry. These pilot study findings suggest that impedance cardiography combined with thigh oscillometry provides comparable results. Intra- and inter-observer variability was tested by two observers in two subjects. We instrumented 41 patients and 12 healthy normotensive controls for impedance cardiography and consecutive applanation tonometry and compared methods using the Bland-Altman method. Observer variability for the impedance-thigh cuff method (range, 3.61%-7.77%) was comparable with the tonometric method (range, 2.93%-7.37%). Comparison of the two methods based on the Bland-Altman plot revealed a good agreement between methods. The bias between impedance and tonometric measurements was -0.28 ± 0.37 m/s. Both measurements were significantly correlated (r(2) = 0.94; P < .0001; slope = 1.038).Impedance cardiography combined with thigh oscillometry is an easy to use approach which, in addition to providing hemodynamic information, yields aPWV measurements comparable to applanation tonometry. Following full validation according to current guidelines, the methodology could prove useful in cardiovascular risk stratification. PMID:25816714

  17. Method of characterizing residual stress in ferromagnetic materials using a pulse histogram of acoustic emission signals

    NASA Technical Reports Server (NTRS)

    Namkung, Min (Inventor); Yost, William T. (Inventor); Kushnick, Peter W. (Inventor); Grainger, John L. (Inventor)

    1992-01-01

    The invention is a method and apparatus for characterizing residual uniaxial stress in a ferromagnetic test member by distinguishing between residual stresses resulting from positive (tension) forces and negative (compression) forces by using the distinct and known magnetoacoustic (MAC) and a magnetoacoustic emission (MAE) measurement circuit means. A switch permits the selective operation of the respective circuit means.

  18. The Dual-Angle Method for Fast, Sensitive T1 Measurement in Vivo with Low-Angle Adiabatic Pulses

    NASA Astrophysics Data System (ADS)

    Bottomley, P. A.; Ouwerkerk, R.

    A new method for measuring T1 based on a measurement of the ratio, R, of the steady-state partially saturated NMR signals acquired at two fixed low flip angles (<90°) and a single sequence-repetition period, TR, is presented, The flip angles are chosen to optimize both the signal-to-noise ratio per unit time relative to the best possible Ernst-angle performance and the sensitivity with which a measurement of R can resolve differences in T1. A flip-angle pair at of around (60°, 15°) yields 70-79% of the maximum achievable Ernst-angle signal-to-noise ratio and a near-linear dependence of R on TR/ T1 with gradient of about 2:1 over the range 0.1 ≤ TR/ T1 ≤ 1. Errors in hip-angle and excitation-field ( B1) inhomogeneity result in roughly proportionate errors in the apparent T1. The method is best implemented with adiabatic low-angle pulses such as B1-independent rotation (BIR-4) or BIR-4 phase-cycled (BIRP) pulses, which permit measurements with surface coils. Experimental validation was obtained at 2 T by comparison of unlocalized inversion-recovery and dual-angle proton ( 1H) and phosphorus ( 31P) measurements from vials containing doped water with 0.04 ≤ T1 ≤ 2.8 s and from the metabolites in the calf muscles of eight human volunteers. Calf muscle values of 6 ± 0.5 s for phosphocreatine and around 3.7 ± 0.8 s for the adenosine triphosphates (ATP) were in good agreement with inversion-recovery T1 values and values from the literature. Use of the dual-angle method accelerated T1 measurement time by about fivefold over inversion recovery. The dual-angle method was implemented in a one-dimensional localized surface-coil 31P spectroscopy sequence, producing consistent T1 measurements from phantoms, the calf muscle, and the human liver. 31P T1 values of ATP in the livers of six volunteers were about 0.5 ± 0.1 to 0.6 ± 0.2 s: the total exam times were about 35 minutes per subject. The method is ideally suited to low-sensitivity and/or low

  19. Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner

    DOEpatents

    Veligdan, James T.

    1994-01-01

    An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90.degree. angle of incidence.

  20. Precursors of molecular hydrogen in the radiolysis of the water-methanol system

    SciTech Connect

    Fel'dman, V.I.; Kovalev, G.V.; Belevskii, V.N.; Bugaenko, L.T.

    1984-11-01

    The dependence of hydrogen yields on c-phenyl-tert-butylnitrone (PBN) concentration in the radiolysis of methanol and methanol water mixtures was studied. The change in the kinetics of H/sub 2/ formation when PBN is added to these mixtures is related to the nature of the radical adducts trapped. 15 references, 1 figure.

  1. A Direct Method to Extract Transient Sub-Gap Density of State (DOS) Based on Dual Gate Pulse Spectroscopy.

    PubMed

    Dai, Mingzhi; Khan, Karim; Zhang, Shengnan; Jiang, Kemin; Zhang, Xingye; Wang, Weiliang; Liang, Lingyan; Cao, Hongtao; Wang, Pengjun; Wang, Peng; Miao, Lijing; Qin, Haiming; Jiang, Jun; Xue, Lixin; Chu, Junhao

    2016-01-01

    Sub-gap density of states (DOS) is a key parameter to impact the electrical characteristics of semiconductor materials-based transistors in integrated circuits. Previously, spectroscopy methodologies for DOS extractions include the static methods, temperature dependent spectroscopy and photonic spectroscopy. However, they might involve lots of assumptions, calculations, temperature or optical impacts into the intrinsic distribution of DOS along the bandgap of the materials. A direct and simpler method is developed to extract the DOS distribution from amorphous oxide-based thin-film transistors (TFTs) based on Dual gate pulse spectroscopy (GPS), introducing less extrinsic factors such as temperature and laborious numerical mathematical analysis than conventional methods. From this direct measurement, the sub-gap DOS distribution shows a peak value on the band-gap edge and in the order of 10(17)-10(21)/(cm(3)·eV), which is consistent with the previous results. The results could be described with the model involving both Gaussian and exponential components. This tool is useful as a diagnostics for the electrical properties of oxide materials and this study will benefit their modeling and improvement of the electrical properties and thus broaden their applications. PMID:27297030

  2. Evaluation and calibration of a pulsed neutron method for total hydrogen determination in mineral and concrete samples

    NASA Astrophysics Data System (ADS)

    Bennun, L.; Santibañez, M.; Gomez, J.; Santisteban, J. R.

    2011-11-01

    We studied the feasibility of a nondestructive method to determine hydrogen concentrations in concrete and mineral samples. The amount of total hydrogen in the sample is directly related to the proportion of water included in the paste preparation; and also considers all subsequent processes which can add or remove hydrogen in a real sample (like rain, evaporation, etc.). The hydrogen proportion is a critical variable in the curing concrete process; its excess or deficiency impacts negatively in the quality of the final product. The proposed technique is based on a pulsed neutron source and the technical support of the time of flight, which allow discriminating epithermal neutrons interacting with hydrogen (inelastic scattering) from the elastic and quasi-isotropic scattering produced by other kinds of atoms. The method was externally calibrated in limestone rocks fragments (CaCO3-main material used in cement fabrication) and in steel, allowing an easy retrieval of the required information. The technique's simplicity may facilitate the development of a mobile measuring device in order to make determinations "in situ." In this paper, we describe the foundations of the proposed method and various analysis results.

  3. A Direct Method to Extract Transient Sub-Gap Density of State (DOS) Based on Dual Gate Pulse Spectroscopy

    NASA Astrophysics Data System (ADS)

    Dai, Mingzhi; Khan, Karim; Zhang, Shengnan; Jiang, Kemin; Zhang, Xingye; Wang, Weiliang; Liang, Lingyan; Cao, Hongtao; Wang, Pengjun; Wang, Peng; Miao, Lijing; Qin, Haiming; Jiang, Jun; Xue, Lixin; Chu, Junhao

    2016-06-01

    Sub-gap density of states (DOS) is a key parameter to impact the electrical characteristics of semiconductor materials-based transistors in integrated circuits. Previously, spectroscopy methodologies for DOS extractions include the static methods, temperature dependent spectroscopy and photonic spectroscopy. However, they might involve lots of assumptions, calculations, temperature or optical impacts into the intrinsic distribution of DOS along the bandgap of the materials. A direct and simpler method is developed to extract the DOS distribution from amorphous oxide-based thin-film transistors (TFTs) based on Dual gate pulse spectroscopy (GPS), introducing less extrinsic factors such as temperature and laborious numerical mathematical analysis than conventional methods. From this direct measurement, the sub-gap DOS distribution shows a peak value on the band-gap edge and in the order of 1017–1021/(cm3·eV), which is consistent with the previous results. The results could be described with the model involving both Gaussian and exponential components. This tool is useful as a diagnostics for the electrical properties of oxide materials and this study will benefit their modeling and improvement of the electrical properties and thus broaden their applications.

  4. Correlated displacement- T2 MRI by means of a Pulsed Field Gradient-Multi Spin Echo method

    NASA Astrophysics Data System (ADS)

    Windt, Carel W.; Vergeldt, Frank J.; Van As, Henk

    2007-04-01

    A method for correlated displacement- T2 imaging is presented. A Pulsed Field Gradient-Multi Spin Echo (PFG-MSE) sequence is used to record T2 resolved propagators on a voxel-by-voxel basis, making it possible to perform single voxel correlated displacement- T2 analyses. In spatially heterogeneous media the method thus gives access to sub-voxel information about displacement and T2 relaxation. The sequence is demonstrated using a number of flow conducting model systems: a tube with flowing water of variable intrinsic T2's, mixing fluids of different T2's in an "X"-shaped connector, and an intact living plant. PFG-MSE can be applied to yield information about the relation between flow, pore size and exchange behavior, and can aid volume flow quantification by making it possible to correct for T2 relaxation during the displacement labeling period Δ in PFG displacement imaging methods. Correlated displacement- T2 imaging can be of special interest for a number of research subjects, such as the flow of liquids and mixtures of liquids or liquids and solids moving through microscopic conduits of different sizes (e.g., plants, porous media, bioreactors, biomats).

  5. Correlated displacement-T2 MRI by means of a Pulsed Field Gradient-Multi Spin Echo Method.

    PubMed

    Windt, Carel W; Vergeldt, Frank J; Van As, Henk

    2007-04-01

    A method for correlated displacement-T2 imaging is presented. A Pulsed Field Gradient-Multi Spin Echo (PFG-MSE) sequence is used to record T2 resolved propagators on a voxel-by-voxel basis, making it possible to perform single voxel correlated displacement-T2 analyses. In spatially heterogeneous media the method thus gives access to sub-voxel information about displacement and T2 relaxation. The sequence is demonstrated using a number of flow conducting model systems: a tube with flowing water of variable intrinsic T2's, mixing fluids of different T2's in an "X"-shaped connector, and an intact living plant. PFG-MSE can be applied to yield information about the relation between flow, pore size and exchange behavior, and can aid volume flow quantification by making it possible to correct for T2 relaxation during the displacement labeling period Delta in PFG displacement imaging methods. Correlated displacement-T2 imaging can be of special interest for a number of research subjects, such as the flow of liquids and mixtures of liquids or liquids and solids moving through microscopic conduits of different sizes (e.g., plants, porous media, bioreactors, biomats). PMID:17236795

  6. A Direct Method to Extract Transient Sub-Gap Density of State (DOS) Based on Dual Gate Pulse Spectroscopy

    PubMed Central

    Dai, Mingzhi; Khan, Karim; Zhang, Shengnan; Jiang, Kemin; Zhang, Xingye; Wang, Weiliang; Liang, Lingyan; Cao, Hongtao; Wang, Pengjun; Wang, Peng; Miao, Lijing; Qin, Haiming; Jiang, Jun; Xue, Lixin; Chu, Junhao

    2016-01-01

    Sub-gap density of states (DOS) is a key parameter to impact the electrical characteristics of semiconductor materials-based transistors in integrated circuits. Previously, spectroscopy methodologies for DOS extractions include the static methods, temperature dependent spectroscopy and photonic spectroscopy. However, they might involve lots of assumptions, calculations, temperature or optical impacts into the intrinsic distribution of DOS along the bandgap of the materials. A direct and simpler method is developed to extract the DOS distribution from amorphous oxide-based thin-film transistors (TFTs) based on Dual gate pulse spectroscopy (GPS), introducing less extrinsic factors such as temperature and laborious numerical mathematical analysis than conventional methods. From this direct measurement, the sub-gap DOS distribution shows a peak value on the band-gap edge and in the order of 1017–1021/(cm3·eV), which is consistent with the previous results. The results could be described with the model involving both Gaussian and exponential components. This tool is useful as a diagnostics for the electrical properties of oxide materials and this study will benefit their modeling and improvement of the electrical properties and thus broaden their applications. PMID:27297030

  7. A unique method to study acoustic transmission through ducts using signal synthesis and averaging of acoustic pulses

    NASA Technical Reports Server (NTRS)

    Salikuddin, M.; Ramakrishnan, R.; Ahuja, K. K.; Brown, W. H.

    1981-01-01

    An acoustic impulse technique using a loudspeaker driver is developed to measure the acoustic properties of a duct/nozzle system. A signal synthesis method is used to generate a desired single pulse with a flat spectrum. The convolution of the desired signal and the inverse Fourier transform of the reciprocal of the driver's response are then fed to the driver. A signal averaging process eliminates the jet mixing noise from the mixture of jet noise and the internal noise, thereby allowing very low intensity signals to be measured accurately, even for high velocity jets. A theoretical analysis is carried out to predict the incident sound field; this is used to help determine the number and locations of the induct measurement points to account for the contributions due to higher order modes present in the incident tube method. The impulse technique is validated by comparing experimentally determined acoustic characteristics of a duct-nozzle system with similar results obtained by the impedance tube method. Absolute agreement in the comparisons was poor, but the overall shapes of the time histories and spectral distributions were much alike.

  8. Multifunctional pulse sequence generator for pulse NMR

    NASA Astrophysics Data System (ADS)

    Wang, Dongsheng

    1988-06-01

    A new multifunctional pulse sequence generator has been designed and constructed. It can conveniently generate various pulse sequences used in nuclear-magnetic resonance (NMR) to measure the spin-lattice relaxation time T1, the spin-spin relaxation time T2, and the spin-locking relaxation time T1 ρ. It can also be used in pulse Fourier transform NMR and double resonance. The intervals of pulses can increase automatically with sequence repetitions and the generator can be used in two-dimensional spectrum measurement and spin-density imaging research. The sequences can be generated through four different triggering methods and there are two synchronous pulse outputs and fifteen auxiliary pulse outputs, so the generator can be conveniently interfaced with a computer or other instruments. The circuitry, functions, and features of the generator are described in this article.

  9. Method and Apparatus for Thermal Spraying of Metal Coatings Using Pulsejet Resonant Pulsed Combustion

    NASA Technical Reports Server (NTRS)

    Paxson, Daniel E. (Inventor)

    2014-01-01

    An apparatus and method for thermal spraying a metal coating on a substrate is accomplished with a modified pulsejet and optionally an ejector to assist in preventing oxidation. Metal such as Aluminum or Magnesium may be used. A pulsejet is first initiated by applying fuel, air, and a spark. Metal is inserted continuously in a high volume of metal into a combustion chamber of the pulsejet. The combustion is thereafter controlled resonantly at high frequency and the metal is heated to a molten state. The metal is then transported from the combustion chamber into a tailpipe of said pulsejet and is expelled therefrom at high velocity and deposited on a target substrate.

  10. A facile method to fabricate superamphiphobic polytetrafluoroethylene surface by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Fan, Wenzhong; Qian, Jing; Bai, Feng; Li, Yangbo; Wang, Chengwei; Zhao, Quan-Zhong

    2016-01-01

    We report a simple method to fabricate superamphiphobic polytetrafluoroethylene (PTFE) surfaces by femtosecond laser direct irradiation. After femtosecond laser direct writing, a dual-scale composite structure combined a groove-like microstructure with a lamellar submicron structure forms on the PTFE surface, enhancing its hydrophobic properties with a contact angle increasing from 109° to 156.88°, as well as exhibiting transition from intrinsic oleophilicity to superoleophobicity. Meanwhile, the wettability of the surface can be tuned by changing the roughness and the interval between two adjacent micro-grooves. Furthermore, we also explain the relationship between the interval width and the contact angle using the Cassie-Baxter model.

  11. Influence of the Duration of Thermal Action on the Errors in Determining the Thermophysical Characteristics of Ceramic Materials by a Laser Pulse Method

    NASA Astrophysics Data System (ADS)

    Kuznetsov, G. V.; Kats, M. D.

    2016-06-01

    An analysis of the errors involved in determining the thermophysical characteristics of a special-purpose ceramic material — zirconium carbide — is made. It is shown that the errors of determining the heat capacity and thermal diffusivity of the indicated material under conditions corresponding to the implementation of the laser pulse method vary nonmonotonically depending on the pulse duration. The possibility of attaining minimum values of methodical errors by appropriately selecting the thickness of a sample and of the time of its heating is shown.

  12. Study of the effects of hydroxyapatite nanocrystal codoping by pulsed electron paramagnetic resonance methods

    NASA Astrophysics Data System (ADS)

    Gafurov, M. R.; Biktagirov, T. B.; Mamin, G. V.; Shurtakova, D. V.; Klimashina, E. S.; Putlyaev, V. I.; Orlinskii, S. B.

    2016-03-01

    The effect of codoping of hydroxyapatite (HAP) nanocrystals with average sizes of 35 ± 15 nm during "wet" synthesis by CO 3 2- carbonate anions and Mn2+ cations on relaxation characteristics (for the times of electron spin-spin relaxation) of the NO 3 2- nitrate radical anion has been studied. By the example of HAP, it has been demonstrated that the electron paramagnetic resonance (EPR) is an efficient method for studying anion-cation (co)doping of nanoscale particles. It has been shown experimentally and by quantummechanical calculations that simultaneous introduction of several ions can be energetically more favorable than their separate inclusion. Possible codoping models have been proposed, and their energy parameters have been calculated.

  13. Methods, systems and apparatus for adjusting duty cycle of pulse width modulated (PWM) waveforms

    SciTech Connect

    Gallegos-Lopez, Gabriel; Kinoshita, Michael H; Ransom, Ray M; Perisic, Milun

    2013-05-21

    Embodiments of the present invention relate to methods, systems and apparatus for controlling operation of a multi-phase machine in a vector controlled motor drive system when the multi-phase machine operates in an overmodulation region. The disclosed embodiments provide a mechanism for adjusting a duty cycle of PWM waveforms so that the correct phase voltage command signals are applied at the angle transitions. This can reduce variations/errors in the phase voltage command signals applied to the multi-phase machine so that phase current may be properly regulated thus reducing current/torque oscillation, which can in turn improve machine efficiency and performance, as well as utilization of the DC voltage source.

  14. Method and Apparatus for Thermal Spraying of Metal Coatings Using Pulsejet Resonant Pulsed Combustion

    NASA Technical Reports Server (NTRS)

    Paxson, Daniel E. (Inventor)

    2010-01-01

    An apparatus and method [or thermal spraying a metal coating on a substrate is accomplished with a modified pulsejet and optionally an ejector to assist in preventing oxidation. Metal such a Aluminum or Magnesium may be used. A pulsejet is first initiated by applying fuel, air. and a spark. Metal is inserted continuously in a high volume of meta1 into a combustion chamber of the pulsejet. The combustion is thereafter. controlled resonantly at high frequency and the metal is heated to a molten state. The metal is then transported from the combustion chamber into a tail pipe of said pulsejet and is expelled therefrom at high velocity and deposited on a target substrate.

  15. Analysis of exosome purification methods using a model liposome system and tunable-resistive pulse sensing

    NASA Astrophysics Data System (ADS)

    Lane, Rebecca E.; Korbie, Darren; Anderson, Will; Vaidyanathan, Ramanathan; Trau, Matt

    2015-01-01

    Exosomes are vesicles which have garnered interest due to their diagnostic and therapeutic potential. Isolation of pure yields of exosomes from complex biological fluids whilst preserving their physical characteristics is critical for downstream applications. In this study, we use 100 nm-liposomes from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol as a model system as a model system to assess the effect of exosome isolation protocols on vesicle recovery and size distribution using a single-particle analysis method. We demonstrate that liposome size distribution and ζ-potential are comparable to extracted exosomes, making them an ideal model for comparison studies. Four different purification protocols were evaluated, with liposomes robustly isolated by three of them. Recovered yields varied and liposome size distribution was unaltered during processing, suggesting that these protocols do not induce particle aggregation. This leads us to conclude that the size distribution profile and characteristics of vesicles are stably maintained during processing and purification, suggesting that reports detailing how exosomes derived from tumour cells differ in size to those from normal cells are reporting a real phenomenon. However, we hypothesize that larger particles present in most purified exosome samples represent co-purified contaminating non-exosome debris. These isolation techniques are therefore likely nonspecific and may co-isolate non-exosome material of similar physical properties.

  16. Analysis of exosome purification methods using a model liposome system and tunable-resistive pulse sensing

    PubMed Central

    Lane, Rebecca E.; Korbie, Darren; Anderson, Will; Vaidyanathan, Ramanathan; Trau, Matt

    2015-01-01

    Exosomes are vesicles which have garnered interest due to their diagnostic and therapeutic potential. Isolation of pure yields of exosomes from complex biological fluids whilst preserving their physical characteristics is critical for downstream applications. In this study, we use 100 nm-liposomes from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol as a model system as a model system to assess the effect of exosome isolation protocols on vesicle recovery and size distribution using a single-particle analysis method. We demonstrate that liposome size distribution and ζ-potential are comparable to extracted exosomes, making them an ideal model for comparison studies. Four different purification protocols were evaluated, with liposomes robustly isolated by three of them. Recovered yields varied and liposome size distribution was unaltered during processing, suggesting that these protocols do not induce particle aggregation. This leads us to conclude that the size distribution profile and characteristics of vesicles are stably maintained during processing and purification, suggesting that reports detailing how exosomes derived from tumour cells differ in size to those from normal cells are reporting a real phenomenon. However, we hypothesize that larger particles present in most purified exosome samples represent co-purified contaminating non-exosome debris. These isolation techniques are therefore likely nonspecific and may co-isolate non-exosome material of similar physical properties. PMID:25559219

  17. Fabrication of one-dimensional alumina photonic crystals by anodization using a modified pulse-voltage method

    SciTech Connect

    Li, Shou-Yi; Wang, Jian; Wang, Gang; Wang, Ji-Zhou; Wang, Cheng-Wei

    2015-08-15

    Highlights: • The alumina multilayer structure with alternating high and low refractive index is fabricated. • This multilayer shows a strong photonic band gap (PBG) and vivid film colors. • The first PBG could be modulated easily by varying the duration time of constant high or low voltages. • Fabrication of the photonic crystal is obtained by directly electrochemical anodization. • The formation mechanism of multilayer is also discussed. - Abstract: The alumina nanolayer structure with alternating high and low porosities is conveniently fabricated by applying a modified pulse voltage waveform with constant high and low voltage. This structure shows the well-defined layer in a long-range structural periodicity leads to a strong photonic band gap (PBG) from visible to near infrared and brilliant film colors. Compared with the previous reported tuning method, this method is more simple and flexible in tuning the PBG of photonic crystals (PCs). The effect of duration time of high, low and 0 V voltages on PBG is discussed. The first PBG could be modulated easily from the visible to near infrared region by varying the duration time of constant high or low voltages. It is also found that the 0 V lasting for appropriate time is helpful to improve the quality of the PCs. The formation mechanism of multilayer is also discussed.

  18. Surface-enhanced Raman scattering-active Au/SiO2 nanocomposites prepared using sonoelectrochemical pulse deposition methods.

    PubMed

    Chang, Chun-Chao; Yang, Kuang-Hsuan; Liu, Yu-Chuan; Hsu, Ting-Chu; Mai, Fu-Der

    2012-09-26

    For improving signals, reproducibility, and stabilities of surface-enhanced Raman scattering (SERS), numerous technologies have recently been reported in the literature. However, the fabrication processes are usually complicated. It is well-known that nanoparticles (NPs) of Au and SiO(2) are SERS active and inactive materials, respectively. In this work, a simple synthesis route based on sonoelectrochemical pulse deposition (SEPD) methods has been developed to synthesize effectively SERS-active Au/SiO(2) nanocomposites (NCs) with an enhancement factor of 5.4 × 10(8). Experimental results indicate that pH value of solution and addition of SiO(2) NPs before and after oxidation-reduction cycles (ORCs) can significantly influence the corresponding SERS activities. Encouragingly, the SERS of Rhodamine 6G (R6G) adsorbed on the developed Au/SiO(2) NCs exhibits a higher intensity by more than 1 order of magnitude, as compared with that of R6G adsorbed on Au NPs synthesized using the same method. Moreover, this improved SERS activity is successfully verified from the mechanisms of electromagnetic (EM) and chemical (CHEM) enhancements. PMID:22934654

  19. Characterization of Positively Charged Lipid Shell Microbubbles with Tunable Resistive Pulse Sensing (TRPS) Method: A Technical Note.

    PubMed

    Manta, Simona; Delalande, Anthony; Bessodes, Michel; Bureau, Michel Francis; Scherman, Daniel; Pichon, Chantal; Mignet, Nathalie

    2016-02-01

    Microbubbles are polydisperse microparticles. Their size distribution cannot be accurately measured from the current methods used, such as optical microscopy, electrical sensing or light scattering. Indeed, these techniques present some limitations when applied to microbubbles, which prompted us to investigate the use of an alternative technique: tunable resistive pulse sensing (TRPS). This technique is based on the principle of the Coulter counter with the advantage of being more flexible compared to other methods using this principle, since the flow rate, the potential difference and the pore size can be modulated. The main limitation of TRPS is that more than one size of nanopore membrane is required to obtain the full size distribution of polydisperse microparticles. To evaluate this technique, the concentration and the size distribution of positively charged microbubbles were studied using TRPS and compared to data obtained using optical microscopy. We describe herein the parameters required for the accurate measurement of microbubble concentration and size distribution by TRPS and present a statistical comparison of the data obtained by TRPS and optical microscopy. PMID:26653937

  20. Investigation of the first-order phase transition kinetics using the method of pulsed photothermal surface deformation: radial measurements

    NASA Astrophysics Data System (ADS)

    Vintzentz, S. V.; Sandomirsky, V. B.

    1992-09-01

    An extension of the photothermal surface deformation (PTSD) method to study the macroscopic kinetics of the first-order phase transition (PTr) is given. The movement of the phase interface (PI) over a surface with a PTr locally induced in the subsurface volume by a focused laser pulse is investigated for the first time using radial measurements of the PTSD kinetics. For the known metal-to-semiconductor PTr in VO 2 (a good model system) a procedure is suggested for measuring the maximum size rsm of the "hot" (metal) phase on the surface (a parameter most difficult to determine) as well as for estimating the velocity of the PI movement over the surface, vs, and in the bulk, vb. Besides, it is shown that the PTSD method may be used to determine the "local" threshold energy E0 needed for the laser-induced PTr and the "local" latent heat L of the PTr. This demonstrates the feasibility of scanning surface E0- and L-microscopy.

  1. Simulation of temperature and thermally induced stress of human tooth under CO2 pulsed laser beams using finite element method.

    PubMed

    Sabaeian, Mohammad; Shahzadeh, Mohammadreza

    2015-02-01

    The authors report the simulation of temperature distribution and thermally induced stresses of human tooth under CO2 pulsed laser beam. A detailed tooth structure comprising enamel, dentin, and pulp with realistic shapes and thicknesses were considered, and a numerical method of finite element was adopted to solve time-dependent bio-heat and stress equations. The realistic boundary conditions of constant temperature for those parts embedded in the gingiva and heat flux condition for those parts out of the gingiva were applied. The results which were achieved as a function of energy density (J/cm(2)) showed when laser beam is irradiated downward (from the top of the tooth), the temperature and thermal stresses decrease quickly as a function of depth that is a result of strong absorption of CO2 beams by enamel. This effect is so influential that one can use CO2 beams to remove micrometer layers while underlying tissues, especially the pulp, are safe from thermal effects. PMID:23868367

  2. Development of a non-thermal accelerated pulsed UV photolysis assisted digestion method for fresh and dried food samples

    NASA Astrophysics Data System (ADS)

    Solís, C.; Lagunas-Solar, M. C.; Perley, B. P.; Piña, C.; Aguilar, L. F.; Flocchini, R. G.

    2002-04-01

    A simple, fast digestion procedure for fresh and dried foods, using high-power pulsed UV photolysis in the presence of hydrogen peroxide, is being developed. The homogenized food samples were mixed with H 2O 2 or with a mixture of H 2O 2 and HNO 3, and irradiated for short times with a 248-nm UV excimer laser. After centrifugation, a clear, colorless solution was obtained and aliquots were deposited on Teflon filters for XRF and/or PIXE analyses. Standard reference materials (NIST Peach Leaves; Typical Diet) were also analyzed to compare recoveries and detection limits. Improvements in detection limits were observed, but a few trace elements (<1 ppm) were not reproducibly detected (Fe, Sr). This method proved to be practical for the accelerated digestion of food samples and preparing analytes in short-time intervals. In combination with PIXE and XRF, it allows high-sensitivity multi-elemental analyses for screening the nutritional elements and for food safety purposes regarding the potential presence of toxic elements. Further development to optimize and validate this procedure for a broader range of analytes is in progress.

  3. Alpha Radiolysis of Sorbed Water on Uranium Oxides and Uranium Oxyfluorides

    SciTech Connect

    Icenhour, A.S.

    2003-09-10

    The radiolysis of sorbed water and other impurities contained in actinide oxides has been the focus of a number of studies related to the establishment of criteria for the safe storage and transport of these materials. Gamma radiolysis studies have previously been performed on uranium oxides and oxyfluorides (UO{sub 3}, U{sub 3}O{sub 8}, and UO{sub 2}F{sub 2}) to evaluate the long-term storage characteristics of {sup 233}U. This report describes a similar study for alpha radiolysis. Uranium oxides and oxyfluorides (with {sup 238}U as the surrogate for {sup 233}U) were subjected to relatively high alpha radiation doses (235 to 634 MGy) by doping with {sup 244}Cm. The typical irradiation time for these samples was about 1.5 years, which would be equivalent to more than 50 years irradiation by a {sup 233}U sample. Both dry and wet (up to 10 wt % water) samples were examined in an effort to identify the gas pressure and composition changes that occurred as a result of radiolysis. This study shows that several competing reactions occur during radiolysis, with the net effect that only very low pressures of hydrogen, nitrogen, and carbon dioxide are generated from the water, nitrate, and carbon impurities, respectively, associated with the oxides. In the absence of nitrate impurities, no pressures greater than 1000 torr are generated. Usually, however, the oxygen in the air atmosphere over the oxides is consumed with the corresponding oxidation of the uranium oxide. In the presence of up to 10 wt % water, the oxides first show a small pressure rise followed by a net decrease due to the oxygen consumption and the attainment of a steady-state pressure where the rate of generation of gaseous components is balanced by their recombination and/or consumption in the oxide phase. These results clearly demonstrate that alpha radiolysis of either wet or dry {sup 233}U oxides will not produce deleterious pressures or gaseous components that could compromise the long-term storage of

  4. Pulse shaping with transmission lines

    DOEpatents

    Wilcox, R.B.

    1985-08-15

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  5. Pulse shaping with transmission lines

    DOEpatents

    Wilcox, Russell B.

    1987-01-01

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  6. Construction of a magnetic bottle spectrometer and its application to pulse duration measurement of X-ray laser using a pump-probe method

    NASA Astrophysics Data System (ADS)

    Namba, S.; Hasegawa, N.; Kishimoto, M.; Nishikino, M.; Ishino, M.; Kawachi, T.

    2015-11-01

    To characterize the temporal evolution of ultrashort X-ray pulses emitted by laser plasmas using a pump-probe method, a magnetic bottle time-of-flight electron spectrometer is constructed. The design is determined by numerical calculations of a mirror magnetic field and of the electron trajectory in a flight tube. The performance of the spectrometer is characterized by measuring the electron spectra of xenon atoms irradiated with a laser-driven plasma X-ray pulse. In addition, two-color above-threshold ionization (ATI) experiment is conducted for measurement of the X-ray laser pulse duration, in which xenon atoms are simultaneously irradiated with an X-ray laser pump and an IR laser probe. The correlation in the intensity of the sideband spectra of the 4d inner-shell photoelectrons and in the time delay of the two laser pulses yields an X-ray pulse width of 5.7 ps, in good agreement with the value obtained using an X-ray streak camera.

  7. Construction of a magnetic bottle spectrometer and its application to pulse duration measurement of X-ray laser using a pump-probe method

    SciTech Connect

    Namba, S.; Hasegawa, N.; Kishimoto, M.; Nishikino, M.; Ishino, M.; Kawachi, T.

    2015-11-15

    To characterize the temporal evolution of ultrashort X-ray pulses emitted by laser plasmas using a pump-probe method, a magnetic bottle time-of-flight electron spectrometer is constructed. The design is determined by numerical calculations of a mirror magnetic field and of the electron trajectory in a flight tube. The performance of the spectrometer is characterized by measuring the electron spectra of xenon atoms irradiated with a laser-driven plasma X-ray pulse. In addition, two-color above-threshold ionization (ATI) experiment is conducted for measurement of the X-ray laser pulse duration, in which xenon atoms are simultaneously irradiated with an X-ray laser pump and an IR laser probe. The correlation in the intensity of the sideband spectra of the 4d inner-shell photoelectrons and in the time delay of the two laser pulses yields an X-ray pulse width of 5.7 ps, in good agreement with the value obtained using an X-ray streak camera.

  8. Prediction of back-scatter radiations to a beam monitor chamber of medical linear accelerators by use of the digitized target-current-pulse analysis method.

    PubMed

    Suzuki, Yusuke; Hayashi, Naoki; Kato, Hideki; Fukuma, Hiroshi; Hirose, Yasujiro; Kawano, Makoto; Nishii, Yoshio; Nakamura, Masaru; Mukouyama, Takashi

    2013-01-01

    In small-field irradiation, the back-scattered radiation (BSR) affects the counts measured with a beam monitor chamber (BMC). In general, the effect of the BSR depends on the opened-jaw size. The effect is significantly large in small-field irradiation. Our purpose in this study was to predict the effect of BSR on LINAC output accurately with an improved target-current-pulse (TCP) technique. The pulse signals were measured with a system consisting of a personal computer and a digitizer. The pulse signals were analyzed with in-house software. The measured parameters were the number of pulses, the change in the waveform and the integrated signal values of the TCPs. The TCPs were measured for various field sizes with four linear accelerators. For comparison, Yu's method in which a universal counter was used was re-examined. The results showed that the variance of the measurements by the new method was reduced to approximately 1/10 of the variance by the previous method. There was no significant variation in the number of pulses due to a change in the field size in the Varian Clinac series. However, a change in the integrated signal value was observed. This tendency was different from the result of other investigations in the past. Our prediction method is able to define the cutoff voltage for the TCP acquired by digitizer. This functionality provides the capability of clearly classifying TCPs into signals and noise. In conclusion, our TCP analysis method can predict the effect of BSR on the BMC even for small-field irradiations. PMID:23096002

  9. A simplified method for quantifying the subject-specific relationship between blood pressure and carotid-femoral pulse wave velocity.

    PubMed

    Butlin, Mark; Hathway, Peta J; Kouchaki, Zahra; Peebles, Karen; Avolio, Alberto P

    2015-08-01

    Devices that estimate blood pressure from arterial pulse wave velocity (PWV) potentially provide continuous, ambulatory blood pressure monitoring. Accurate blood pressure estimation requires reliable quantification of the relationship between blood pressure and PWV. Regression to population normal values or, when using limb artery PWV, changing hydrostatic blood pressure within the limb provides a calibration index. Population lookup tables require accurate anthropometric correlates, assuming no individual variation. Only devices that measure PWV in the limb can use limb position changes. This study proposes a method for developing a calibration curve independent of lookup tables and useful for large artery PWV measurement, such as carotid-femoral PWV (PWVcf). PWVcf was measured in 27 normal subjects (15 female, 36±19 years) in both the supine and standing position. The change in systemic pressure was measured and hydrostatic pressure change calculated from estimated vessel path length height, measured using body surface distances. Brachial diastolic blood pressure increased for all subjects from supine to standing (supine 70±8 mmHg, standing 83±8 mmHg, p<;0.001) with an additional hydrostatic change across the carotid-femoral path length of 19±2 mmHg (p<;0.001). PWVcf also increased in all subjects (supine 5.2±1.3 m/s, standing 7.3±2.2 m/s, p<;0.001). The subject-specific calibration index (ΔDP/ΔPWVcf) varied amongst the cohort (20±8 mmHg/m/s), was correlated with age (-0.57, p=0.002) and seated aortic systolic pressure (-0.38, p=0.048) and was always greater than zero. Thus, this study describes a simple but novel method of measuring an individualized calibration index using blood pressure and PWV measurements in the supine and standing position. PMID:26737588

  10. Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner

    DOEpatents

    Veligdan, J.T.

    1994-03-08

    An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90[degree] angle of incidence. 8 figures.

  11. Passive and active pulse stacking scheme for pulse shaping

    DOEpatents

    Harney, Robert C.; Schipper, John F.

    1977-01-01

    Apparatus and method for producing a sequence of radiation pulses with a pulse envelope of time variation which is controllable by an external electromagnetic signal applied to an active medium or by a sectored reflector, through which the radiation passes.

  12. Efficient optical pulse stacker system

    DOEpatents

    Seppala, Lynn G.; Haas, Roger A.

    1982-01-01

    Method and apparatus for spreading and angle-encoding each pulse of a multiplicity of small area, short pulses into several temporally staggered pulses by use of appropriate beam splitters, with the optical elements being arranged so that each staggered pulse is contiguous with one or two other such pulses, and the entire sequence of stacked pulses comprising a single, continuous long pulse. The single long pulse is expanded in area, and then doubly passed through a nonstorage laser amplifier such as KrF. After amplification, the physically separated, angle-encoded and temporally staggered pulses are recombined into a single pulse of short duration. This high intensity output beam is well collimated and may be propagated over long distance, or used for irradiating inertial confinement fusion targets.

  13. Radiolysis as a solution for accelerated ageing studies of electrolytes in Lithium-ion batteries.

    PubMed

    Ortiz, Daniel; Steinmetz, Vincent; Durand, Delphine; Legand, Solène; Dauvois, Vincent; Maître, Philippe; Le Caër, Sophie

    2015-01-01

    Diethyl carbonate and dimethyl carbonate are prototype examples of eco-friendly solvents used in lithium-ion batteries. Nevertheless, their degradation products affect both the battery performance and its safety. Therefore, it is of paramount importance to understand the reaction mechanisms involved in the ageing processes. Among those, redox processes are likely to play a critical role. Here we show that radiolysis is an ideal tool to generate the electrolytes degradation products. The major gases detected after irradiation (H2, CH4, C2H6, CO and CO2) are identified and quantified. Moreover, the chemical compounds formed in the liquid phase are characterized by different mass spectrometry techniques. Reaction mechanisms are then proposed. The detected products are consistent with those of the cycling of Li-based cells. This demonstrates that radiolysis is a versatile and very helpful tool to better understand the phenomena occurring in lithium-ion batteries. PMID:25907411

  14. Radiolysis as a solution for accelerated ageing studies of electrolytes in Lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Ortiz, Daniel; Steinmetz, Vincent; Durand, Delphine; Legand, Solène; Dauvois, Vincent; Maître, Philippe; Le Caër, Sophie

    2015-04-01

    Diethyl carbonate and dimethyl carbonate are prototype examples of eco-friendly solvents used in lithium-ion batteries. Nevertheless, their degradation products affect both the battery performance and its safety. Therefore, it is of paramount importance to understand the reaction mechanisms involved in the ageing processes. Among those, redox processes are likely to play a critical role. Here we show that radiolysis is an ideal tool to generate the electrolytes degradation products. The major gases detected after irradiation (H2, CH4, C2H6, CO and CO2) are identified and quantified. Moreover, the chemical compounds formed in the liquid phase are characterized by different mass spectrometry techniques. Reaction mechanisms are then proposed. The detected products are consistent with those of the cycling of Li-based cells. This demonstrates that radiolysis is a versatile and very helpful tool to better understand the phenomena occurring in lithium-ion batteries.

  15. Radiolysis as a solution for accelerated ageing studies of electrolytes in Lithium-ion batteries

    PubMed Central

    Ortiz, Daniel; Steinmetz, Vincent; Durand, Delphine; Legand, Solène; Dauvois, Vincent; Maître, Philippe; Le Caër, Sophie

    2015-01-01

    Diethyl carbonate and dimethyl carbonate are prototype examples of eco-friendly solvents used in lithium-ion batteries. Nevertheless, their degradation products affect both the battery performance and its safety. Therefore, it is of paramount importance to understand the reaction mechanisms involved in the ageing processes. Among those, redox processes are likely to play a critical role. Here we show that radiolysis is an ideal tool to generate the electrolytes degradation products. The major gases detected after irradiation (H2, CH4, C2H6, CO and CO2) are identified and quantified. Moreover, the chemical compounds formed in the liquid phase are characterized by different mass spectrometry techniques. Reaction mechanisms are then proposed. The detected products are consistent with those of the cycling of Li-based cells. This demonstrates that radiolysis is a versatile and very helpful tool to better understand the phenomena occurring in lithium-ion batteries. PMID:25907411

  16. Radiolysis of the AV-17×8 ČS anion-exchange resin

    NASA Astrophysics Data System (ADS)

    Bartoníček, B.; Habersbergerová, A.; Janovský, I.; Kysela, J.; Pejša, R.

    The mixture of the anion exchange resin AV-17×8 čs in borate form and of a deaerated aqueous solution containing H 3BO 3 and NH 3 ( pH = 7) was irradiated with gamma rays in both static and dynamic conditions. A loss of strong-base exchange capacity and an increase of weak-base capacity was observed. In the solution, (CH 3) 3N, (CH 3) 2NH and CH 3NH 2 were found as the radiolytic products, their relative ratio being 15.7 : 3.7 : 1. Further, NH 3 is formed with the concentration of the same order as that of CH 3NH 2. Beside hydrogen, which is the prevailing gaseous product of the radiolysis of the mixture, methane and ethane arise, their ratio in the dynamic irradiation being 2.8 to 6.0. The main features of the radiolysis are outlined.

  17. Muon radiolysis affected by density inhomogeneity in near-critical fluids.

    PubMed

    Cormier, P J; Alcorn, C; Legate, G; Ghandi, K

    2014-04-01

    In this article we show the significant tunability of radiation chemistry in supercritical ethane and to a lesser extent in near critical CO2. The information was obtained by studies of muonium (Mu = μ(+)e(-)), which is formed by the thermalization of positive muons in different materials. The studies of the proportions of three fractions of muon polarization, PMu, diamagnetic PD and lost fraction, PL provided the information on radiolysis processes involved in muon thermalization. Our studies include three different supercritical fluids, water, ethane and carbon dioxide. A combination of mobile electrons and other radiolysis products such as (•)C2H5 contribute to interesting behavior at densities ∼40% above the critical point in ethane. In carbon dioxide, an increase in electron mobility contributes to the lost fraction. The hydrated electron in water is responsible for the lost fraction and decreases the muonium fraction. PMID:24641627

  18. Room temperature synthesis of Ni-based alloy nanoparticles by radiolysis.

    SciTech Connect

    Nenoff, Tina Maria; Berry, Donald T.; Lu, Ping; Leung, Kevin; Provencio, Paula Polyak; Stumpf, Roland Rudolph; Huang, Jian Yu; Zhang, Zhenyuan

    2009-09-01

    Room temperature radiolysis, density functional theory, and various nanoscale characterization methods were used to synthesize and fully describe Ni-based alloy nanoparticles (NPs) that were synthesized at room temperature. These complementary methods provide a strong basis in understanding and describing metastable phase regimes of alloy NPs whose reaction formation is determined by kinetic rather than thermodynamic reaction processes. Four series of NPs, (Ag-Ni, Pd-Ni, Co-Ni, and W-Ni) were analyzed and characterized by a variety of methods, including UV-vis, TEM/HRTEM, HAADF-STEM and EFTEM mapping. In the first focus of research, AgNi and PdNi were studied. Different ratios of Ag{sub x}- Ni{sub 1-x} alloy NPs and Pd{sub 0.5}- Ni{sub 0.5} alloy NP were prepared using a high dose rate from gamma irradiation. Images from high-angle annular dark-field (HAADF) show that the Ag-Ni NPs are not core-shell structure but are homogeneous alloys in composition. Energy filtered transmission electron microscopy (EFTEM) maps show the homogeneity of the metals in each alloy NP. Of particular interest are the normally immiscible Ag-Ni NPs. All evidence confirmed that homogeneous Ag-Ni and Pd-Ni alloy NPs presented here were successfully synthesized by high dose rate radiolytic methodology. A mechanism is provided to explain the homogeneous formation of the alloy NPs. Furthermore, studies of Pd-Ni NPs by in situ TEM (with heated stage) shows the ability to sinter these NPs at temperatures below 800 C. In the second set of work, CoNi and WNi superalloy NPs were attempted at 50/50 concentration ratios using high dose rates from gamma irradiation. Preliminary results on synthesis and characterization have been completed and are presented. As with the earlier alloy NPs, no evidence of core-shell NP formation occurs. Microscopy results seem to indicate alloying occurred with the CoNi alloys. However, there appears to be incomplete reduction of the Na{sub 2}WO{sub 4} to form the W

  19. SNMR pulse sequence phase cycling

    DOEpatents

    Walsh, David O; Grunewald, Elliot D

    2013-11-12

    Technologies applicable to SNMR pulse sequence phase cycling are disclosed, including SNMR acquisition apparatus and methods, SNMR processing apparatus and methods, and combinations thereof. SNMR acquisition may include transmitting two or more SNMR pulse sequences and applying a phase shift to a pulse in at least one of the pulse sequences, according to any of a variety cycling techniques. SNMR processing may include combining SNMR from a plurality of pulse sequences comprising pulses of different phases, so that desired signals are preserved and indesired signals are canceled.

  20. Sensitivity of UO2 Stability in a Reducing Environment on Radiolysis Model Parameters

    SciTech Connect

    Wittman, Richard S.; Buck, Edgar C.

    2012-09-01

    Results for a radiolysis model sensitivity study of radiolytically produced H2O2 are presented as they relate to Spent (or Used) Light Water Reactor uranium oxide (UO2) nuclear fuel (UNF) oxidation in a low oxygen environment. The model builds on previous reaction kinetic studies to represent the radiolytic processes occurring at the nuclear fuel surface. Hydrogen peroxide (H2O2) is the dominant oxidant for spent nuclear fuel in an O2-depleted water environment.

  1. EVIDENCE OF CORROSIVE GAS FORMED BY RADIOLYSIS OF CHLORIDE SALTS IN PLUTONIUM-BEARING MATERIALS

    SciTech Connect

    Dunn, K.; Louthan, M.

    2010-02-01

    Corrosion and pitting have been observed in headspace regions of stainless steel containers enclosing plutonium oxide/salt mixtures. These observations are consistent with the formation of a corrosive gas, probably HCl, and transport of that gas to the headspace regions of sealed containers. The NH{sub 4}Cl films found on the walls of the sealed containers is also indicative of the presence of HCl gas. Radiolysis of hydrated alkaline earth salts is the probable source of HCl.

  2. Diagnostics of atmospheric-pressure pulsed-dc discharge with metal and liquid anodes by multiple laser-aided methods

    NASA Astrophysics Data System (ADS)

    Urabe, Keiichiro; Shirai, Naoki; Tomita, Kentaro; Akiyama, Tsuyoshi; Murakami, Tomoyuki

    2016-08-01

    The density and temperature of electrons and key heavy particles were measured in an atmospheric-pressure pulsed-dc helium discharge plasma with a nitrogen molecular impurity generated using system with a liquid or metal anode and a metal cathode. To obtain these parameters, we conducted experiments using several laser-aided methods: Thomson scattering spectroscopy to obtain the spatial profiles of electron density and temperature, Raman scattering spectroscopy to obtain the neutral molecular nitrogen rotational temperature, phase-modulated dispersion interferometry to determine the temporal variation of the electron density, and time-resolved laser absorption spectroscopy to analyze the temporal variation of the helium metastable atom density. The electron density and temperature measured by Thomson scattering varied from 2.4  ×  1014 cm‑3 and 1.8 eV at the center of the discharge to 0.8  ×  1014 cm‑3 and 1.5 eV near the outer edge of the plasma in the case of the metal anode, respectively. The electron density obtained with the liquid anode was approximately 20% smaller than that obtained with the metal anode, while the electron temperature was not significantly affected by the anode material. The molecular nitrogen rotational temperatures were 1200 K with the metal anode and 1650 K with the liquid anode at the outer edge of the plasma column. The density of helium metastable atoms decreased by a factor of two when using the liquid anode.

  3. INSTRUMENTS AND METHODS OF INVESTIGATION: Giant pulses of thermal neutrons in large accelerator beam dumps. Possibilities for experiments

    NASA Astrophysics Data System (ADS)

    Stavissky, Yurii Ya

    2006-12-01

    A short review is presented of the development in Russia of intense pulsed neutron sources for physical research — the pulsating fast reactors IBR-1, IBR-30, IBR-2 (Joint Institute for Nuclear Research, Dubna), and the neutron-radiation complex of the Moscow meson factory — the 'Troitsk Trinity' (RAS Institute for Nuclear Research, Troitsk, Moscow region). The possibility of generating giant neutron pulses in beam dumps of superhigh energy accelerators is discussed. In particular, the possibility of producing giant pulsed thermal neutron fluxes in modified beam dumps of the large hadron collider (LHD) under construction at CERN is considered. It is shown that in the case of one-turn extraction ov 7-TeV protons accumulated in the LHC main rings on heavy targets with water or zirconium-hydride moderators placed in the front part of the LHC graphite beam-dump blocks, every 10 hours relatively short (from ~100 µs) thermal neutron pulses with a peak flux density of up to ~1020 neutrons cm-2 s-1 may be produced. The possibility of applying such neutron pulses in physical research is discussed.

  4. Sources of pulsed radiation

    SciTech Connect

    Sauer, M.C. Jr.

    1981-01-01

    Characteristics of various sources of pulsed radiation are examined from the viewpoint of their importance to the radiation chemist, and some examples of uses of such sources are mentioned. A summary is given of the application of methods of physical dosimetry to pulsed sources, and the calibration of convenient chemical dosimeters by physical dosimetry is outlined. 7 figures, 1 table.

  5. Extrusion cooking: Legume pulses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extrusion is used commercially to produce high value breakfast and snack foods based on cereals such as wheat or corn. However, this processing method is not being commercially used for legume pulses seeds due to the perception that they do not expand well in extrusion. Extrusion cooking of pulses (...

  6. Pulse Oximetry

    MedlinePlus

    ... www.thoracic.org amount of gases (oxygen and carbon dioxide) that are in your blood. To get an ... Also, a pulse oximeter does not measure your carbon dioxide level. How accurate is the pulse oximeter? The ...

  7. Long range detection of line-array multi-pulsed coding lidar by combining the Accumulation coherence and Subpixel-energy detection method.

    PubMed

    Su, Jinshan; Wang, Yuanqing; Liang, Dongdong

    2015-06-15

    This paper presents a multi-pulsed line-array push broom lidar, the pixel array scale reaches Geiger mode detectors in time-of-flight (TOF) depth imaging: by using time and space correlation between array elements of array avalanche photo detector (APD), light coding technology and a diode pumped solid-state laser with 10kHz repetition rate and 5µJ per pulses. Two signal enhancement methods, accumulation-coherence and high accuracy energy detection were combined improves the decode effect and realizes further long detection range. Experimental results and theory analysis indicating that the retrieval and denoising results of both simulated and real signals demonstrate that our method is practical and effective; what's more, the increasing scale of array sensor and the code bits can further improve system performance. PMID:26193500

  8. PULSE GENERATOR

    DOEpatents

    Roeschke, C.W.

    1957-09-24

    An improvement in pulse generators is described by which there are produced pulses of a duration from about 1 to 10 microseconds with a truly flat top and extremely rapid rise and fall. The pulses are produced by triggering from a separate input or by modifying the current to operate as a free-running pulse generator. In its broad aspect, the disclosed pulse generator comprises a first tube with an anode capacitor and grid circuit which controls the firing; a second tube series connected in the cathode circuit of the first tube such that discharge of the first tube places a voltage across it as the leading edge of the desired pulse; and an integrator circuit from the plate across the grid of the second tube to control the discharge time of the second tube, determining the pulse length.

  9. The radiolysis of aqueous solutions containing dithiothreitol and oxidized dithiothreitol

    NASA Astrophysics Data System (ADS)

    John Elliot, A.; Sopchyshyn, Frederick C.

    The radiation chemistry of aqueous solutions (pH 1-9) of dithiothreitol (DTT) has been investigated by pulsed and steady-state techniques. From G( H2S) in N 2- and N 2O-saturated solutions it was concluded for pH 5-9 that the majority of the solvated electrons and 25-40% of the hydroxyl radicals reacted with DTT to form H 2S. Oxidized dithiothreitol (DTT- ox) was the other major product observed for pH 5-9. However, DTT- ox was not formed when DTT solutions were irradiated at pH 1 and 2. When nitrate ions were added as an electron scavenger over the pH range 5-9, G( DTT- ox) was not affected; at pH 9.0 G( H2S) decreased slightly but at pH 5-6, G( H2S) was reduced to that arising from the reaction of the hydroxyl radical. The reaction of CO 2- with DTT- ox was studied at pH 4.6 and pH 9.0. At pH 9.0 the G( DTT)=3.3-0.2 indicated a simple two electron reduction of DTT- ox while at pH 4.6 the G( DTT) >25 implied a chain reaction had occurred.

  10. Effects of the duty ratio on the niobium oxide film deposited by pulsed-DC magnetron sputtering methods.

    PubMed

    Eom, Ji Mi; Oh, Hyun Gon; Cho, Il Hwan; Kwon, Sang Jik; Cho, Eou Sik

    2013-11-01

    Niobium oxide (Nb2O5) films were deposited on p-type Si wafers and sodalime glasses at a room temperature using in-line pulsed-DC magnetron sputtering system with various duty ratios. The different duty ratio was obtained by varying the reverse voltage time of pulsed DC power from 0.5 to 2.0 micros at the fixed frequency of 200 kHz. From the structural and optical characteristics of the sputtered NbOx films, it was possible to obtain more uniform and coherent NbOx films in case of the higher reverse voltage time as a result of the cleaning effect on the Nb2O5 target surface. The electrical characteristics from the metal-insulator-semiconductor (MIS) fabricated with the NbOx films shows the leakage currents are influenced by the reverse voltage time and the Schottky barrier diode characteristics. PMID:24245329

  11. Method for determining the position, angle and other injection parameters of a short pulsed beam in the Brookhaven AGS

    SciTech Connect

    Gardner, C.; Ahrens, L.

    1985-01-01

    As part of the effort to improve the monitoring of the injection process at the Brookhaven Alternating Gradient Synchrotron (AGS), we have developed a beam diagnostics package which processes the signals from the plates of a pick-up electrode (PUE) located near the injection region of the AGS and provides measurements of the position and angle (with respect to the equilibrium orbit) of the injected beam at the stripping foil where the incident H/sup -/ beam is converted into protons. In addition the package provides measurements of the tune and chromaticity of the AGS at injection, and a measurement of the momentum spread of the injected beam. Since these parameters are obtained for a short-pulsed beam at injection we shall refer to the diagnostics package as PIP which stands for Pulsed Injection Parameters.

  12. Pulse stretcher

    DOEpatents

    Horton, J.A.

    1994-05-03

    Apparatus for increasing the length of a laser pulse to reduce its peak power without substantial loss in the average power of the pulse is disclosed. The apparatus uses a White cell having a plurality of optical delay paths of successively increasing number of passes between the field mirror and the objective mirrors. A pulse from a laser travels through a multi-leg reflective path between a beam splitter and a totally reflective mirror to the laser output. The laser pulse is also simultaneously injected through the beam splitter to the input mirrors of the optical delay paths. The pulses from the output mirrors of the optical delay paths go simultaneously to the laser output and to the input mirrors of the longer optical delay paths. The beam splitter is 50% reflective and 50% transmissive to provide equal attenuation of all of the pulses at the laser output. 6 figures.

  13. Calibration of sap flow estimated by the compensation heat pulse method in olive, plum and orange trees: relationships with xylem anatomy.

    PubMed

    Fernández, J E; Durán, P J; Palomo, M J; Diaz-Espejo, A; Chamorro, V; Girón, I F

    2006-06-01

    The compensation heat pulse method is widely used to estimate sap flow in conducting organs of woody plants. Being an invasive technique, calibration is crucial to derive correction factors for accurately estimating the sap flow value from the measured heat pulse velocity. We compared the results of excision and perfusion calibration experiments made with mature olive (Olea europaea L. 'Manzanilla de Sevilla'), plum (Prunus domestica L. 'Songal') and orange (Citrus sinensis (L.) Osbeck. 'Cadenero') trees. The calibration experiments were designed according to current knowledge on the application of the technique and the analysis of measured heat pulse velocities. Data on xylem characteristics were obtained from the experimental trees and related to the results of the calibration experiments. The most accurate sap flow values were obtained by assuming a wound width of 2.0 mm for olive and 2.4 mm for plum and orange. Although the three possible methods of integrating the sap velocity profiles produced similar results for all three species, the best results were obtained by calculating sap flow as the weighted sum of the product of sap velocity and the associated sapwood area across the four sensors of the heat-pulse-velocity probes. Anatomical observations showed that the xylem of the studied species can be considered thermally homogeneous. Vessel lumen diameter in orange trees was about twice that in the olive and plum, but vessel density was less than half. Total vessel lumen area per transverse section of xylem tissue was greater in plum than in the other species. These and other anatomical and hydraulic differences may account for the different calibration results obtained for each species. PMID:16510387

  14. Pulsed power

    NASA Astrophysics Data System (ADS)

    Stone, David H.

    Pulsed power systems are critical elements for such prospective weapons technologies as high-power microwaves, electrothermal and electromagnetic projectile launchers, neutral particle beams, space-based FELs, ground-based lasers, and charged particle beams. Pulsed power will also be essential for the development of nonweapon military systems such as lidars and ultrawideband radars, and could serve as the bases for nuclear weapon effect simulators. The pulsed power generation requirements for each of these systems is considered.

  15. Pulse Voltammetry

    NASA Astrophysics Data System (ADS)

    Stojek, Zbigniew

    The idea of imposing potential pulses and measuring the currents at the end of each pulse was proposed by Barker in a little-known journal as early as in 1958 [1]. However, the first reliable trouble-free and affordable polarographs offering voltammetric pulse techniques appeared on the market only in the 1970s. This delay was due to some limitations on the electronic side. In the 1990s, again substantial progress in electrochemical pulse instrumentation took place. This was related to the introduction of microprocessors, computers, and advanced software.

  16. A Review of Radiolysis Concerns for Water Shielding in Fission Surface Power Applications

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael P.

    2008-01-01

    This paper presents an overview of radiolysis concerns with regard to water shields for fission surface power. A review of the radiolysis process is presented and key parameters and trends are identified. From this understanding of the radiolytic decomposition of water, shield pressurization and corrosion are identified as the primary concerns. Existing experimental and modeling data addressing concerns are summarized. It was found that radiolysis of pure water in a closed volume results in minimal, if any net decomposition, and therefore reduces the potential for shield pressurization and corrosion. With the space program focus m emphasize more on permanent return to the Moon and eventually manned exploration of Mars, there has been a renewed look at fission power to meet the difficult technical & design challenges associated with this effort. This is due to the ability of fission power to provide a power rich environment that is insensitive to solar intensity and related aspects such as duration of night, dusty environments, and distance from the sun, etc. One critical aspect in the utilization of fission power for these applications of manned exploration is shielding. Although not typically considered for space applications, water shields have been identified as one potential option due to benefits in mass savings and reduced development cost and technical risk (Poston, 2006). However, the water shield option requires demonstration of its ability to meet key technical challenges including such things as adequate natural circulation for thermal management and capability for operational periods up to 8 years. Thermal management concerns have begun to be addressed and are not expected to be a problem (Pearson, 2007). One significant concern remaining is the ability to maintain the shield integrity through its operational lifetime. Shield integrity could be compromised through shield pressurization and corrosion resulting from the radiolytic decomposition of water.

  17. Identification of tetraphenylborate radiolysis products in a simulated feedstock for radioactive waste processing

    SciTech Connect

    Eibling, R.E.; Bartlett, M.G.; Carlson, R.E.; Testino, S.A. Jr.; Kunkel, G.J.; Browner, R.F.; Busch, K.L.

    1994-10-01

    The first step towards immobilization of the soluble radioactive species in borosilicate glass is the addition of sodium tetraphenylborate (TPB) and sodium titanate to the radioactive aqueous solution. Initial studies of the TPB hydrolysis process have found that some component of the radiolysis mixture inactivates the Cu catalyst. The interaction of organic materials with the catalyst, and the subsequent interference with the hydrolysis process, would have presented problems with the use of the vitrification process. Prevention of the catalyst deactivation is obtained by washing the irradiated TPB precipitate in the Late Wash Facility prior to hydrolysis to remove the soluble radiolysis products. Identification of the organic radiolysis products, their distribution in the Late Wash Facility, and their interactions with the Cu catalyst has become an important analytical issue. To further investigate the reaction products of the TPB precipitation process, a simulated feedstock was created from compounds known to be present in the starting materials. This simulated feedstock was precipitated with sodium TPB and then exposed to Co-60 gamma radiation to simulate two years of additional storage time prior to the hydrolysis process. The irradiated product was divided into two parts, the filtered supernatant liquid and the precipitate slurry, which contains the TPB and the solid sodium titanate. Using gas chromatography/mass spectrometry, liquid secondary ion mass spectrometry, inductively coupled plasma/mass spectrometry, ion chromatography, and high performance liquid chromatography, over 50 organic and inorganic species have been identified in the aqueous portion of a simulated feedstock for TPB hydrolysis. The major organic species present are benzene, phenol, benzamide and a variety of substituted phenylphenols. The major inorganic species present are sodium, nitrite, and oxalate ions.

  18. Role of the low-energy excited states in the radiolysis of aromatic liquids.

    PubMed

    Baidak, Aliaksandr; Badali, Matthew; LaVerne, Jay A

    2011-07-01

    The contribution of the low-energy excited states to the overall product formation in the radiolysis of simple aromatic liquids--benzene, pyridine, toluene, and aniline--has been examined by comparison of product yields obtained in UV-photolysis and in γ-radiolysis. In photolysis, these electronic excited states were selectively populated using UV-light excitation sources with various energies. Yields of molecular hydrogen and of "dimers" (biphenyl, bibenzyl, dipyridyl for benzene, toluene, pyridine, respectively, and of ammonia and diphenylamine for aniline) have been determined, since they are the most abundant radiolytic products. Negligibly small production of molecular hydrogen in the UV-photolysis of aromatic liquids with excitation to energies of 4.88, 5.41, 5.79, and 6.70 eV and the lack of a scavenger effect suggest that this product originates from short-lived high-energy singlet states. A significant reduction in "dimer" radiation-chemical yields in the presence of scavengers such as anthracene or naphthalene indicates that the triplet excited states are important precursors to these products. The results for toluene and aniline suggest that efficient dissociation from the lowest-energy excited triplet state leads to noticeable "dimer" production. For benzene and pyridine, the lowest-energy triplet excited states are not likely to fragment into radicals because of the relatively large energy gap between the excited state level and corresponding bond dissociation energy. The "dimer" formation in the radiolysis of benzene and pyridine is likely to involve short-lived high-energy triplet states. PMID:21634362

  19. γ-Radiolysis of branched chain hydrocarbons: 2,4-dimethylpentane

    NASA Astrophysics Data System (ADS)

    Castello, Gianrico; D'Amato, Giuseppina; Tealdo, Giancarlo

    The γ-radiolysis of liquid 2,4-dimethylpentane was investigated vacuo as a function of total dose in the range 0.5-2.7 × 10 20 eV g -1. Iodine was used as a scavenger to identify the primary radicals, the alkyl iodides so formed being analysed by gas chromatography with ECD. The radiation-chemical yields of rupture of the various C-H and C-C bonds of the molecule were calculated and compared with the corresponding values for similar bonds in other branched-chain alkanes.

  20. The possible role of hydrothermal vents in chemical evolution: Succinic acid radiolysis and thermolysis

    NASA Astrophysics Data System (ADS)

    Cruz-Castañeda, J.; Colín-García, M.; Negrón-Mendoza, A.

    2014-07-01

    In this research, the behavior under a high radiation field or high temperature of succinic acid, a dicarboxylic acid clue in metabolic routes, is studied. For this purpose, the molecule was irradiated with gamma rays in oxygen-free aqueous solutions, and the thermal decomposition was studied in a static system at temperatures up to 90 °C, simulating a white hydrothermal vent. Our results indicate that a succinic acid is a relatively stable compound under irradiation. The gamma radiolysis yields carbon dioxide and di- and tricarboxylic acids such as malonic, carboxysuccinic, and citric acids. The main products obtained by the thermal treatment were CO2 and propionic acid.