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Sample records for ionization methods final

  1. Analytical instruments, ionization sources, and ionization methods

    DOEpatents

    Atkinson, David A.; Mottishaw, Paul

    2006-04-11

    Methods and apparatus for simultaneous vaporization and ionization of a sample in a spectrometer prior to introducing the sample into the drift tube of the analyzer are disclosed. The apparatus includes a vaporization/ionization source having an electrically conductive conduit configured to receive sample particulate which is conveyed to a discharge end of the conduit. Positioned proximate to the discharge end of the conduit is an electrically conductive reference device. The conduit and the reference device act as electrodes and have an electrical potential maintained between them sufficient to cause a corona effect, which will cause at least partial simultaneous ionization and vaporization of the sample particulate. The electrical potential can be maintained to establish a continuous corona, or can be held slightly below the breakdown potential such that arrival of particulate at the point of proximity of the electrodes disrupts the potential, causing arcing and the corona effect. The electrical potential can also be varied to cause periodic arcing between the electrodes such that particulate passing through the arc is simultaneously vaporized and ionized. The invention further includes a spectrometer containing the source. The invention is particularly useful for ion mobility spectrometers and atmospheric pressure ionization mass spectrometers.

  2. Chemical protection against ionizing radiation. Final report

    SciTech Connect

    Livesey, J.C.; Reed, D.J.; Adamson, L.F.

    1984-08-01

    The scientific literature on radiation-protective drugs is reviewed. Emphasis is placed on the mechanisms involved in determining the sensitivity of biological material to ionizing radiation and mechanisms of chemical radioprotection. In Section I, the types of radiation are described and the effects of ionizing radiation on biological systems are reviewed. The effects of ionizing radiation are briefly contrasted with the effects of non-ionizing radiation. Section II reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Inlcuded in the list of these factors are water, oxygen, thiols, vitamins and antioxidants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) in determining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described in Section III. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. 495 references.

  3. Ionized Gaseous Nebulae Abundance Determination from the Direct Method

    NASA Astrophysics Data System (ADS)

    Pérez-Montero, Enrique

    2017-04-01

    This tutorial explains the procedure used to analyze an optical emission-line spectrum produced by a nebula ionized by massive star formation. Particularly, the methodology used to derive physical properties, such as electron density and temperature, and the ionic abundances of the most representative elements whose emission lines are present in the optical spectrum is described. The main focus is on the direct method, which is based on the measurement of the electron temperature to derive the abundances, given that the ionization and thermal equilibrium of the ionized gas is dominated by the metallicity. The ionization correction factors used to obtain total abundances from the abundances of some of their ions are also given. Finally, some strong-line methods to derive abundances are described. Such methods are used when no estimation of the temperature can be derived, but which can be consistent with the direct method if they are empirically calibrated.

  4. Method and apparatus to monitor a beam of ionizing radiation

    DOEpatents

    Blackburn, Brandon W.; Chichester, David L.; Watson, Scott M.; Johnson, James T.; Kinlaw, Mathew T.

    2015-06-02

    Methods and apparatus to capture images of fluorescence generated by ionizing radiation and determine a position of a beam of ionizing radiation generating the fluorescence from the captured images. In one embodiment, the fluorescence is the result of ionization and recombination of nitrogen in air.

  5. Matrix Assisted Ionization Vacuum (MAIV), a New Ionization Method for Biological Materials Analysis Using Mass Spectrometry*

    PubMed Central

    Inutan, Ellen D.; Trimpin, Sarah

    2013-01-01

    The introduction of electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) for the mass spectrometric analysis of peptides and proteins had a dramatic impact on biological science. We now report that a wide variety of compounds, including peptides, proteins, and protein complexes, are transported directly from a solid-state small molecule matrix to gas-phase ions when placed into the vacuum of a mass spectrometer without the use of high voltage, a laser, or added heat. This ionization process produces ions having charge states similar to ESI, making the method applicable for high performance mass spectrometers designed for atmospheric pressure ionization. We demonstrate highly sensitive ionization using intermediate pressure MALDI and modified ESI sources. This matrix and vacuum assisted soft ionization method is suitable for the direct surface analysis of biological materials, including tissue, via mass spectrometry. PMID:23242551

  6. Matrix assisted ionization in vacuum, a sensitive and widely applicable ionization method for mass spectrometry.

    PubMed

    Trimpin, Sarah; Inutan, Ellen D

    2013-05-01

    An astonishingly simple new method to produce gas-phase ions of small molecules as well as proteins from the solid state under cold vacuum conditions is described. This matrix assisted ionization vacuum (MAIV) mass spectrometry (MS) method produces multiply charged ions similar to those that typify electrospray ionization (ESI) and uses sample preparation methods that are nearly identical to matrix-assisted laser desorption/ionization (MALDI). Unlike these established methods, MAIV does not require a laser or voltage for ionization, and unlike the recently introduced matrix assisted ionization inlet method, does not require added heat. MAIV-MS requires only introduction of a crystalline mixture of the analyte incorporated with a suitable small molecule matrix compound such as 3-nitrobenzonitrile directly to the vacuum of the mass spectrometer. Vacuum intermediate pressure MALDI sources and modified ESI sources successfully produce ions for analysis by MS with this method. As in ESI-MS, ion formation is continuous and, without a laser, little chemical background is observed. MAIV, operating from a surface offers the possibility of significantly improved sensitivity relative to atmospheric pressure ionization because ions are produced in the vacuum region of the mass spectrometer eliminating losses associated with ion transfer from atmospheric pressure to vacuum. Mechanistic aspects and potential applications for this new ionization method are discussed.

  7. Soft ionization device with characterization systems and methods of manufacture

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T. (Inventor)

    2004-01-01

    Various configurations of characterization systems such as ion mobility spectrometers and mass spectrometers are disclosed that are coupled to an ionization device. The ionization device is formed of a membrane that houses electrodes therein that are located closer to one another than the mean free path of the gas being ionized. Small voltages across the electrodes generate large electric fields which act to ionize substantially all molecules passing therethrough without fracture. Methods to manufacture the mass spectrometer and ion mobility spectrometer systems are also described.

  8. Investigation of metal evaporation by the laser ionization method

    SciTech Connect

    Kasimov, A.K.; Tursunov, A.T.

    1995-04-01

    Evaporation rates and vapor pressures of metallic gallium are measured, and spatial structures of gallium atomic beams are studied using the method of laser stepwise selective excitation of atoms and their ionization by the electric field.

  9. Microliter-sized ionization device and method

    NASA Technical Reports Server (NTRS)

    Cohen, Martin J. (Inventor); Simac, Robert M. (Inventor); Wernlund, Roger F. (Inventor)

    1999-01-01

    A microliter-sized metastable ionization device with a cavity, a sample gas inlet, a corona gas inlet and a gas outlet. A first electrode has a hollow and disposed in the cavity and is in fluid communication with the sample gas inlet. A second electrode is in fluid communication with the corona gas inlet and is disposed around the first electrode adjacent the hollow end thereof. A gap forming means forms a corona gap between the first and second electrodes. A first power supply is connected to the first electrode and the second power supply is connected to the second electrode for generating a corona discharge across the corona gap. A collector has a hollow end portion disposed in the cavity which is in fluid communications with the gas outlet for the outgassing and detection of ionized gases. The first electrode can be a tubular member aligned concentrically with a cylindrical second electrode. The gap forming means can be in annular disc projecting radially inwardly from the cylindrical second electrode. The collector can have a tubular opening aligned coaxially with the first electrode and has an end face spaced a short distance from an end face of the first electrode forming a small active volume therebetween for the generation and detection of small quantities of trace analytes.

  10. Multiphoton ionization of ions, neutrals, and clusters. Final report

    SciTech Connect

    Wessel, J.

    1995-12-28

    A multiyear research program investigating molecular detection methods based on multiphoton spectroscopy has been completed under DOE sponsorship. A number of new laser-based spectroscopic methods were developed and applied to a variety of aromatic hydrocarbons, including monomer and cluster species. The objectives of sensitivities approaching single molecule detection combined with high selectivity were achieved. This report references the status of the field at the beginning of this work and summarizes the significant progress during the period from 1987 onward. Detailed scientific findings from the studies are presented in the published literature referenced throughout this report.

  11. Kinetic correlation in the final-state wave function in photo-double-ionization of He

    SciTech Connect

    Otranto, S.; Garibotti, C. R.

    2003-06-01

    We evaluate the triply differential cross section (TDCS) for photo-double-ionization of helium. We use a final continuum wave function which correlates the motion of the three particles, through an expansion in products of two-body Coulomb functions. This function satisfies a set of appropriate physical conditions in the coalescence points, in addition to the correct asymptotic behavior condition. We analyze the effect of this correlation in the TDCS and compare our results with experimental data.

  12. High resolution resonance ionization imaging detector and method

    DOEpatents

    Winefordner, James D.; Matveev, Oleg I.; Smith, Benjamin W.

    1999-01-01

    A resonance ionization imaging device (RIID) and method for imaging objects using the RIID are provided, the RIID system including a RIID cell containing an ionizable vapor including monoisotopic atoms or molecules, the cell being positioned to intercept scattered radiation of a resonance wavelength .lambda..sub.1 from the object which is to be detected or imaged, a laser source disposed to illuminate the RIID cell with laser radiation having a wavelength .lambda..sub.2 or wavelengths .lambda..sub.2, .lambda..sub.3 selected to ionize atoms in the cell that are in an excited state by virtue of having absorbed the scattered resonance laser radiation, and a luminescent screen at the back surface of the RIID cell which presents an image of the number and position of charged particles present in the RIID cell as a result of the ionization of the excited state atoms. The method of the invention further includes the step of initially illuminating the object to be detected or imaged with a laser having a wavelength selected such that the object will scatter laser radiation having the resonance wavelength .lambda..sub.1.

  13. Systems and methods for cylindrical hall thrusters with independently controllable ionization and acceleration stages

    DOEpatents

    Diamant, Kevin David; Raitses, Yevgeny; Fisch, Nathaniel Joseph

    2014-05-13

    Systems and methods may be provided for cylindrical Hall thrusters with independently controllable ionization and acceleration stages. The systems and methods may include a cylindrical channel having a center axial direction, a gas inlet for directing ionizable gas to an ionization section of the cylindrical channel, an ionization device that ionizes at least a portion of the ionizable gas within the ionization section to generate ionized gas, and an acceleration device distinct from the ionization device. The acceleration device may provide an axial electric field for an acceleration section of the cylindrical channel to accelerate the ionized gas through the acceleration section, where the axial electric field has an axial direction in relation to the center axial direction. The ionization section and the acceleration section of the cylindrical channel may be substantially non-overlapping.

  14. [Method on ozone generation with strong ionization discharge].

    PubMed

    Zhang, Z; Han, H; Chu, Q; Bai, X

    2001-03-01

    This paper presents the formed methods of strong ionization discharge of dielectric barrier and plasma chemical reaction process of ozone generation. Ozone combination and decomposition are controlled by electric field intensity and electron energy. Therefore, new technologies with thinner dielectric layers (230 microns) of model alpha Al2O3 and narrow discharge gap (110 microns) are introduced, and strong ionization discharge is gained which reduced field (E) and electron average energy are more than 400Td and 10 eV respectively. Ozone concentration reaches to 200 g/m3 and ozone producing efficiency is 100 g/(kW.h). Ozone generator of big yield and miniaturization with module assembled method is realized.

  15. Immersed interface methods. Final report

    SciTech Connect

    LeVeque, R.J.; Adams, L.M.; Bube, K.P.

    1996-11-01

    Cartesian grid methods encompass a wide variety of techniques used to solve partial differential equations in more than one space dimension on uniform Cartesian grids even when the underlying geometry is complex and not aligned with the grid. The authors` groups work on Immersed Interface Methods (IIM) was originally motivated by the desire to understand and improve the ``Immersed Boundary Method``, developed by Charles Peskin to solve incompressible Navier-Stokes equations in complicated geometries with moving elastic boundaries. This report briefly discusses the development of the Immersed Interface Methods and gives examples of application of the method in solving several partial differential equations.

  16. Capillary atmospheric pressure electron capture ionization (cAPECI): a highly efficient ionization method for nitroaromatic compounds.

    PubMed

    Derpmann, Valerie; Mueller, David; Bejan, Iustinian; Sonderfeld, Hannah; Wilberscheid, Sonja; Koppmann, Ralf; Brockmann, Klaus J; Benter, Thorsten

    2014-03-01

    We report on a novel method for atmospheric pressure ionization of compounds with elevated electron affinity (e.g., nitroaromatic compounds) or gas phase acidity (e.g., phenols), respectively. The method is based on the generation of thermal electrons by the photo-electric effect, followed by electron capture of oxygen when air is the gas matrix yielding O2(-) or of the analyte directly with nitrogen as matrix. Charge transfer or proton abstraction by O2(-) leads to the ionization of the analytes. The interaction of UV-light with metals is a clean method for the generation of thermal electrons at atmospheric pressure. Furthermore, only negative ions are generated and neutral radical formation is minimized, in contrast to discharge- or dopant assisted methods. Ionization takes place inside the transfer capillary of the mass spectrometer leading to comparably short transfer times of ions to the high vacuum region of the mass spectrometer. This strongly reduces ion transformation processes, resulting in mass spectra that more closely relate to the neutral analyte distribution. cAPECI is thus a soft and selective ionization method with detection limits in the pptV range. In comparison to standard ionization methods (e.g., PTR), cAPECI is superior with respect to both selectivity and achievable detection limits. cAPECI demonstrates to be a promising ionization method for applications in relevant fields as, for example, explosives detection and atmospheric chemistry.

  17. Computerized accounting methods. Final report

    SciTech Connect

    1994-12-31

    This report summarizes the results of the research performed under the Task Order on computerized accounting methods in a period from 03 August to 31 December 1994. Computerized nuclear material accounting methods are analyzed and evaluated. Selected methods are implemented in a hardware-software complex developed as a prototype of the local network-based CONMIT system. This complex has been put into trial operation for test and evaluation of the selected methods at two selected ``Kurchatov Institute`` Russian Research Center (``KI`` RRC) nuclear facilities. Trial operation is carried out since the beginning of Initial Physical Inventory Taking in these facilities that was performed in November 1994. Operation of CONMIT prototype system was demonstrated in the middle of December 1994. Results of evaluation of CONMIT prototype system features and functioning under real operating conditions are considered. Conclusions are formulated on the ways of further development of computerized nuclear material accounting methods. The most important conclusion is a need to strengthen computer and information security features supported by the operating environment. Security provisions as well as other LANL Client/Server System approaches being developed by Los Alamos National Laboratory are recommended for selection of software and hardware components to be integrated into production version of CONMIT system for KI RRC.

  18. Ionization detector, electrode configuration and single polarity charge detection method

    DOEpatents

    He, Zhong

    1998-01-01

    An ionization detector, an electrode configuration and a single polarity charge detection method each utilize a boundary electrode which symmetrically surrounds first and second central interlaced and symmetrical electrodes. All of the electrodes are held at a voltage potential of a first polarity type. The first central electrode is held at a higher potential than the second central or boundary electrodes. By forming the first and second central electrodes in a substantially interlaced and symmetrical pattern and forming the boundary electrode symmetrically about the first and second central electrodes, signals generated by charge carriers are substantially of equal strength with respect to both of the central electrodes. The only significant difference in measured signal strength occurs when the charge carriers move to within close proximity of the first central electrode and are received at the first central electrode. The measured signals are then subtracted and compared to quantitatively measure the magnitude of the charge.

  19. Ionization detector, electrode configuration and single polarity charge detection method

    DOEpatents

    He, Z.

    1998-07-07

    An ionization detector, an electrode configuration and a single polarity charge detection method each utilize a boundary electrode which symmetrically surrounds first and second central interlaced and symmetrical electrodes. All of the electrodes are held at a voltage potential of a first polarity type. The first central electrode is held at a higher potential than the second central or boundary electrodes. By forming the first and second central electrodes in a substantially interlaced and symmetrical pattern and forming the boundary electrode symmetrically about the first and second central electrodes, signals generated by charge carriers are substantially of equal strength with respect to both of the central electrodes. The only significant difference in measured signal strength occurs when the charge carriers move to within close proximity of the first central electrode and are received at the first central electrode. The measured signals are then subtracted and compared to quantitatively measure the magnitude of the charge. 10 figs.

  20. Method and an apparatus for detecting ionizable substance

    NASA Technical Reports Server (NTRS)

    McElroy, James F. (Inventor); Smith, William (Inventor)

    1992-01-01

    The amount of ionizable substance within a stream can be continuously monitored through the use of an ionizable substance detector. The substance is ionized at an electrode producing ions and free electrons. The ions are transported across an ion exchange membrane, while the free electrons flow through a power source. The current, produced by the electrons, is proportional to the amount of substance in the stream. Continuous monitoring can be useful in early detection of problems, or system fluctuations.

  1. Evaluation of Gas-filled Ionization Chamber Method for Radon Measurement at Two Reference Facilities

    SciTech Connect

    Ishikawa, Tetsuo; Tokonami, Shinji; Kobayashi, Yosuke; Sorimachi, Atsuyuki; Yatabe, Yoshinori; Miyahara, Nobuyuki

    2008-08-07

    For quality assurance, gas-filled ionization chamber method was tested at two reference facilities for radon calibration: EML (USA) and PTB (Germany). Consequently, the radon concentrations estimated by the ionization chamber method were in good agreement with the reference radon concentrations provided by EML as well as PTB.

  2. Metal ion complexation by ionizable crown ethers. Final report, January 1, 1988--June 30, 1994

    SciTech Connect

    Bartsch, R.A.

    1994-12-31

    During the report period a variety of new lipophilic ionizable crown ethers with pendent proton-ionizable groups has been synthesized. The ligands possess one or more ionizable group (carboxylic acid, phosphonic acid monoethyl ester, para-nitrophenol, phosphonic acid) attached to crown ether, monoazacrown ether or diazacrown ether frameworks. These novel chelating agents have either pendent or inward-facing proton-ionizable groups. Such lipophilic proton-ionizable crown ethers are designed for use in multiphase metal ion separations (solvent extraction, liquid membrane transport). In addition a series of proton-ionizable crown ethers without lipophilic groups was prepared to study how structural variations within the ligand influence metal ion complexation in homogeneous media as assessed by NMR spectroscopy or titration calorimetry. A third class of new metal ion-complexing agents is a series of lipophilic acyclic polyether dicarboxylic acids. Competitive solvent extractions of alkali metal and alkaline earth cations and of the mixed species have been conducted to reveal the influence of ring size, nature and attachment site of the lipophilic group, sidearm length, and proton-ionizable group identity and location upon the selectivity and efficiency of metal ion complexation. In addition to such studies of structural variation within the lipophilic proton-ionizable crown ether, the effect of changing the organic solvent and variation of the stripping conditions have been assessed. The influence of structural variations within lipophilic acyclic polyether dicarboxylic acids upon competitive solvent extraction of alkaline earth cations has been probed. Also a new chromogenic, di-ionizable crown ether with extremely high selectivity for Hg{sup 2+} has been discovered.

  3. Radial arrays of nano-electrospray ionization emitters and methods of forming electrosprays

    DOEpatents

    Kelly, Ryan T [West Richland, WA; Tang, Keqi [Richland, WA; Smith, Richard D [Richland, WA

    2010-10-19

    Electrospray ionization emitter arrays, as well as methods for forming electrosprays, are described. The arrays are characterized by a radial configuration of three or more nano-electrospray ionization emitters without an extractor electrode. The methods are characterized by distributing fluid flow of the liquid sample among three or more nano-electrospray ionization emitters, forming an electrospray at outlets of the emitters without utilizing an extractor electrode, and directing the electrosprays into an entrance to a mass spectrometry device. Each of the nano-electrospray ionization emitters can have a discrete channel for fluid flow. The nano-electrospray ionization emitters are circularly arranged such that each is shielded substantially equally from an electrospray-inducing electric field.

  4. Evaluation of the computational methods for electron-impact total ionization cross sections: Fluoromethanes as benchmarks

    NASA Astrophysics Data System (ADS)

    Torres, I.; Martínez, R.; Sánchez Rayo, M. N.; Castaño, F.

    2001-09-01

    The experimental electron-impact total ionization cross sections (TICSs, ICSs) of CF4, CHF3, CH2F2, and CH3F fluoromethanes reported so far and a new set of data obtained with a linear double focusing time-of-flight mass spectrometer have been compared with the ab initio and (semi)empirical based ICS available methods. TICSs computational methods include: two approximations of the binary-encounter dipole (BED) referred to hereafter as Kim (Kim-BEB) and Khare (Khare-BEB) methods, the Deutsch and Märk (DM) formalism, also requiring atomic and molecular ab initio information, the modified additivity rule (MAR), and the Harland and Vallance (HV) methods, both based on semiempirical or empirical correlations. The molecular ab initio information required by the Kim, Khare, and DM methods has been computed at a variety of quantum chemistry levels, with and without electron correlation and a comprehensive series of basis sets. The general conclusions are summarized as follows: the Kim method yields TICS in excellent agreement with the experimental method; the Khare method provides TICS very close to that of Kim at low electron-impact energies (<100 eV), but their Mott and Bethe contributions are noticeably different; in the Kim and Khare approximations the electron correlation methods improve the fittings to the experimental profiles in contrast with the large basis sets, that leads to poorer results; the DM formalism yields TICS profiles with shapes similar to the experimental and the BEB methods, but consistently lower and with the profiles maxima shifted towards lower incident electron energies; the MAR method supplies very good ICS profiles, between those of BEB and DM methods; finally, the empirical HV method provides rather poor fittings concomitant with the simplicity and the few empirical parameters used.

  5. A method to determine the ionization efficiency change of peptides caused by phosphorylation.

    PubMed

    Gao, Yuan; Wang, Yinsheng

    2007-11-01

    Quantitative assessment of post-translational modifications in proteins by mass spectrometry often requires the consideration of the alteration in ionization efficiency of peptides induced by the modification. Herein, we introduced a method to measure the relative ionization efficiencies of peptides using specifically designed unlabeled peptides. In our design, the peptide under study, in either the unmodified or modified form, is linked with an internal standard peptide via an enzyme cleavage site; thus, after enzymatic digestion, we could obtain readily a 1:1 ratio between the peptide under investigation and the internal standard peptide. The relative ionization efficiencies of the modified and unmodified peptides can then be calculated from the modification-induced change in the ratio of relative abundances of the ion of the peptide of interest over that of the internal standard peptide. We demonstrated the usefulness of the method by assessing the change in ionization efficiencies of four peptides introduced by phosphorylation.

  6. Ionizing radiation post-curing of objects produced by stereolithography and other methods

    DOEpatents

    Howell, David H.; Eberle, Claude C.; Janke, Christopher J.

    2000-01-01

    An object comprised of a curable material and formed by stereolithography or another three-dimensional prototyping method, in which the object has undergone initial curing, is subjected to post-curing by ionizing radiation, such as an electron beam having a predetermined beam output energy, which is applied in a predetermined dosage and at a predetermined dose rate. The post-cured object exhibits a property profile which is superior to that which existed prior to the ionizing radiation post-curing.

  7. Effects of ionizing radiation on the developing embryo and fetus: a review. Final report

    SciTech Connect

    Hoffman, D.A.; Felten, R.P.; Cyr, W.H.

    1981-08-01

    A general review of the literature dealing with effects of ionizing radiation on the developing embryo and fetus. Encompasses both experimental and epidemiological data based on the age of the organism at exposure, with major emphasis on exposure during pregnancy. An appendix presents this information in table format. This review consists of three main sections: experimental, genetic, and epidemiological. These sections are organized according to the age of the organism at the time of irradiation. Data are presented by period of development and endpoints observed. In addition to the individual section summaries, an overall summation is presented.

  8. Inter-Individual Variability in Human Response to Low-Dose Ionizing Radiation, Final Report

    SciTech Connect

    Rocke, David

    2016-08-01

    In order to investigate inter-individual variability in response to low-dose ionizing radiation, we are working with three models, 1) in-vivo irradiated human skin, for which we have a realistic model, but with few subjects, all from a previous project, 2) ex-vivo irradiated human skin, for which we also have a realistic model, though with the limitations involved in keeping skin pieces alive in media, and 3) MatTek EpiDermFT skin plugs, which provides a more realistic model than cell lines, which is more controllable than human samples.

  9. Real-time monitoring of volatile organic compounds using chemical ionization mass spectroscopy: Final report

    SciTech Connect

    Thornberg, S.M.; Mowry, C.D.; Keenan, M.R.; Bender, S.F.A.; Owen, T.

    1997-04-01

    Volatile organic compound (VOC) emission to the atmosphere is of great concern to semiconductor manufacturing industries, research laboratories, the public, and regulatory agencies. Some industries are seeking ways to reduce emissions by reducing VOCs at the point of use (or generation). This paper discusses the requirements, design, calibration, and use of a sampling inlet/quadrupole mass spectrometer system for monitoring VOCs in a semiconductor manufacturing production line. The system uses chemical ionization to monitor compounds typically found in the lithography processes used to manufacture semiconductor devices (e.g., acetone, photoresist). The system was designed to be transportable from tool to tool in the production line and to give the operator real-time feedback so the process(es) can be adjusted to minimize VOC emissions. Detection limits ranging from the high ppb range for acetone to the low ppm range fore other lithography chemicals were achieved using chemical ionization mass spectroscopy at a data acquisition rate of approximately 1 mass spectral scan (30 to 200 daltons) per second. A demonstration of exhaust VOC monitoring was performed at a working semiconductor fabrication facility during actual wafer processing.

  10. INSTRUMENTS AND METHODS OF INVESTIGATION: Surface-ionization field mass-spectrometry studies of nonequilibrium surface ionization

    NASA Astrophysics Data System (ADS)

    Blashenkov, Nikolai M.; Lavrent'ev, Gennadii Ya

    2007-01-01

    The ionization of polyatomic molecules on tungsten and tungsten oxide surfaces is considered for quasiequilibrium or essentially nonequilibrium conditions (in the latter case, the term nonequilibrium surface ionization is used for adsorbate ionization). Heterogeneous reactions are supposed to proceed through monomolecular decay of polyatomic molecules or fragments of multimolecular complexes. The nonequilibrium nature of these reactions is established. The dependences of the current density of disordered ions on the surface temperature, electric field strength, and ionized particle energy distribution are obtained in analytical form. Heterogeneous dissociation energies, the ionization potentials of radicals, and the magnitude of reaction departure from equilibrium are determined from experimental data, as are energy exchange times between reaction products and surfaces, the number of molecules in molecular complexes, and the number of effective degrees of freedom in molecules and complexes. In collecting the data a new technique relying on surface-ionization field mass-spectrometry was applied.

  11. Validity boundary of orbital-free molecular dynamics method corresponding to thermal ionization of shell structure

    NASA Astrophysics Data System (ADS)

    Gao, Chang; Zhang, Shen; Kang, Wei; Wang, Cong; Zhang, Ping; He, X. T.

    2016-11-01

    With 6LiD as an example, we show that the applicable region of the orbital-free molecular dynamics (OFMD) method in a large temperature range is determined by the thermal ionization process of bound electrons in shell structures. The validity boundary of the OFMD method is defined roughly by the balance point of the average thermal energy of an electron and the ionization energy of the lowest localized electronic state. This theoretical proposition is based on the observation that the deviation of the OFMD method originates from its less accurate description to the charge density in partially ionized shells, as compared with the results of the extended first-principles molecular dynamics method, which well reproduces the charge density of shell structures.

  12. Virtual detector methods for efficiently computing momentum-resolved dissociation and ionization spectra

    NASA Astrophysics Data System (ADS)

    Kramer, Alex; Thumm, Uwe

    2016-05-01

    We discuss a class of window-transform-based ``virtual detector'' methods for computing momentum-resolved dissociation and ionization spectra by numerically analyzing the motion of nuclear or electronic quantum-mechanical wavepackets at the periphery of their numerical grids. While prior applications of such surface-flux methods considered semi-classical limits to derive ionization and dissociation spectra, we systematically include quantum-mechanical corrections and extensions to higher dimensions, discussing numerical convergence properties and the computational efficiency of our method in comparison with alternative schemes for obtaining momentum distributions. Using the example of atomic ionization by co- and counter-rotating circularly polarized laser pulses, we scrutinize the efficiency of common finite-difference schemes for solving the time-dependent Schrödinger equation in virtual detection and standard Fourier-transformation methods for extracting momentum spectra. Supported by the DoE, NSF, and Alexander von Humboldt foundation.

  13. Method for the depth corrected detection of ionizing events from a co-planar grids sensor

    DOEpatents

    De Geronimo, Gianluigi; Bolotnikov, Aleksey E.; Carini, Gabriella

    2009-05-12

    A method for the detection of ionizing events utilizing a co-planar grids sensor comprising a semiconductor substrate, cathode electrode, collecting grid and non-collecting grid. The semiconductor substrate is sensitive to ionizing radiation. A voltage less than 0 Volts is applied to the cathode electrode. A voltage greater than the voltage applied to the cathode is applied to the non-collecting grid. A voltage greater than the voltage applied to the non-collecting grid is applied to the collecting grid. The collecting grid and the non-collecting grid are summed and subtracted creating a sum and difference respectively. The difference and sum are divided creating a ratio. A gain coefficient factor for each depth (distance between the ionizing event and the collecting grid) is determined, whereby the difference between the collecting electrode and the non-collecting electrode multiplied by the corresponding gain coefficient is the depth corrected energy of an ionizing event. Therefore, the energy of each ionizing event is the difference between the collecting grid and the non-collecting grid multiplied by the corresponding gain coefficient. The depth of the ionizing event can also be determined from the ratio.

  14. Improved gas chromatography-flame ionization detector analytical method for the analysis of epoxy fatty acids.

    PubMed

    Mubiru, Edward; Shrestha, Kshitij; Papastergiadis, Antonios; De Meulenaer, Bruno

    2013-11-29

    In this study an improved method for analysis of epoxy fatty acids is reported. Data obtained from analysis of polar fatty acids has previously been presented, but due to the high number of compounds that co-elute in the polar fraction, the resultant chromatograms are complex which may lead to compromising the accuracy of the data. A three steps separation of fatty acid methyl esters (FAMEs) by solid-phase extraction (SPE) on a silica gel column to remove hydroxy fatty acid interferences was proposed. This approach is opposed to a two step separation procedure that has been often used to prevent analytical interferences caused by non-altered fatty acids. A gas chromatograph with a flame ionization detector (GC-FID) equipped with a polar CP-Sil 88™ column was used. Quantification was based on the use of methyl nonadecanoate (C19:0), as an internal standard. Individual mono epoxy fatty acids were well separated without co-eluting compounds. The optimized method was finally applied to screen epoxy fatty acids in 37 fresh oil samples. Results obtained for the total epoxy fatty acids were in the range 0.03-2mgg(-1) of oil with repeatability coefficient of variation (CV) ranging from 2.8 to 9.9% for duplicate analysis showing that the results obtained are repeatable.

  15. Criteria for the operation of federally-owned secondary calibration laboratories (ionizing radiation). Special pub. (Final)

    SciTech Connect

    Eisenhower, E.H.

    1991-08-01

    The document contains standards of performance for laboratories that calibrate instrumentation used to measure ionizing radiation. Such standards are useful for the development of a secondary level of calibration laboratories that can provide a high-quality link between the National Institute of Standards and Technology and those who make routine measurements at the field level. The standards may also be used as criteria on which a decision is based regarding accreditation of a particular laboratory. They were developed by representatives of federally-owned laboratories that perform calibrations of the type addressed by the document. The first major part contains general criteria that must be satisfied by all laboratories seeking accreditation. It includes requirements relating to management and staff, physical aspects of the laboratory, calibrations facilities and equipment, operational procedures, accuracy and quality assurance, and records and reports. Five subsequent major parts establish criteria for calibration of survey instruments, irradiation of personnel dosimeters, calibration of sources, calibration of instruments for diagnostic levels, and calibration of reference-class instruments. The types of radiation covered include gamma rays, x rays, beta particles, neutrons, and alpha particles. An appendix describes the proficiency tests administered by NIST to secondary laboratories as a prerequisite for their accreditation.

  16. Genetic variation in resistance to ionizing radiation. Final report, January 1, 1990--December 31, 1992

    SciTech Connect

    Ayala, F.J.

    1992-12-31

    Results of an investigation of the gene coding for Cu, Zn superoxide dismutase (Sod) in Drosophila melanogaster seeking to understand the enzyme`s role in cell protection against ionizing radiation are reported. Components of the investigation include molecular characterization of the gene; measuring the response of different genotypes to increasing levels of radiation; and investigation of the processes that maintain the Sod polymorphism in populations. While two alleles, S and F, are commonly found at the Sod locus in natural populations of D. melanogaster we have isolated from a natural population a null (CA1) mutant that yields only 3.5% of normal SOD activity. The S, F, and CA1 alleles provide a model system to investigate SOD-dependent radioresistance, because each allele yields different levels of SOD, so that S > F >> CAl. The radioprotective effects of SOD can be established by showing protective effects for the various genotypes that correspond to those inequalities. Because the allele variants studied are derived from natural populations, the proposed investigation avoids problems that arise when mutants obtained my mutagenesis are used. Moreover, each allele is studied in multiple genetic backgrounds, so that we correct for effects attributable to other loci by randomizing these effects.

  17. Technical note: a method for improving the calibration reproducibility of an ionization chamber detector array.

    PubMed

    Goodall, Simon; Morgan, Steve

    2014-09-01

    This paper describes an extension to a wide field calibration method implemented on a commercial detector array in order to improve the reproducibility of the calibration procedure. Following the standard array calibration procedure, two additional 10×10 cm exposures were acquired for each array axis with the detector array shifted by ±10 cm in the transverse or axial axes, or by ±10√2 cm in the positive or negative diagonal axes. These exposures were compared with a final baseline 10×10 cm exposure captured with the detector repositioned at the isocenter. The measurements were used to calculate a linear off-axis correction gradient which was then applied to the stored calibration factors. The mean coefficient of variation between five repeat calibrations was reduced from 4.17% to 0.48% and the maximum percentage error in individual calibration factors was reduced from 6.46% to 0.77%. The reproducibility of the calibration factors of an ionization chamber array was increased by capturing a baseline exposure and two further off-axis readings per calibration axis.

  18. Method for loading lipsomes with ionizable phosphorylated hydrophobic compounds, pharmaceutical preparations and a method for administering the preparations

    DOEpatents

    Mehlhorn, R.J.

    1998-10-27

    A method of entrapping ionizable compounds, preferably phosphorylated hydrophobic compounds, into liposomes having transmembrane gradients is disclosed. The procedures involve forming liposomes in an acidic medium or a basic medium, adding to the acidic medium a cationic compound or to the basic medium an anionic compound and then adding a base to the cationic-containing medium or an acid to the anionic-containing medium, thereby inducing the ionizable compound into the liposomes` internal aqueous phase. The compound-entrapped liposomes prepared in accordance with the disclosed methods may be used as pharmaceutical preparations. Methods of administering such pharmaceutical preparations are also disclosed. 2 figs.

  19. Method for loading lipsomes with ionizable phosphorylated hydrophobic compounds, pharmaceutical preparations and a method for administering the preparations

    DOEpatents

    Mehlhorn, Rolf Joachim

    1998-10-27

    A method of entrapping ionizable compounds, preferably phosphorylated hydrophobic compounds, into liposomes having transmembrane gradients is disclosed. The procedures involve forming liposomes in an acidic medium or a basic medium, adding to the acidic medium a cationic compound or to the basic medium an anionic compound and then adding a base to the cationic-containing medium or an acid to the anionic-containing medium, thereby inducing the ionizable compound into the liposomes' internal aqueous phase. The compound-entrapped liposomes prepared in accordance with the disclosed methods may be used as pharmaceutical preparations. Methods of administering such pharmaceutical preparations are also disclosed.

  20. Method of isotope separation by chemi-ionization

    DOEpatents

    Wexler, Sol; Young, Charles E.

    1977-05-17

    A method for separating specific isotopes present in an isotopic mixture by aerodynamically accelerating a gaseous compound to form a jet of molecules, and passing the jet through a stream of electron donor atoms whereby an electron transfer takes place, thus forming negative ions of the molecules. The molecular ions are then passed through a radiofrequency quadrupole mass filter to separate the specific isotopes. This method may be used for any compounds having a sufficiently high electron affinity to permit negative ion formation, and is especially useful for the separation of plutonium and uranium isotopes.

  1. Alternate cleaning methods for LCCAs. Final report

    SciTech Connect

    Adams, B.E.

    1993-04-01

    The purpose of this project was to evaluate DI water followed by isopropyl alcohol (IPA) cleaning and no cleaning of leadless chip carriers (LCCs). Both environmentally safe methods were to be tested against the current chlorofluorocarbon (CFC) material cleaning baseline. Several experiments were run to compare production and electrical yields of LCCs cleaned by all three methods. The critical process steps most affected by cleaning were wire bonding, sealing, particle induced noise detection (PIND), moisture content, and electrical. Yields for the experimental lots cleaned by CFC, DI water plus IPA, and no cleaning were 56%, 72%, and 75%, respectively. The overall results indicated that vapor degreasing/ultrasonic cleaning in CFCs could be replaced by the aqueous method. No cleaning could also be considered if an effective dry method of particle removal could be developed.

  2. Ionization in liquids. Final technical report, November 1, 1993--December 31, 1995

    SciTech Connect

    Bakale, G.

    1996-03-29

    The objective of these studies which began in 1993 was to provide new information on electron and ion transport and reactions in model liquids and biomimetic systems that is pertinent to the roles of charged species in inducing radiobiological damage and to elucidate the interrelationship among the carcinogenicity, mutagenicity and electrophilicity of chemicals. This final report summarizes research efforts in the following areas: electrons in biological systems; and electron and ion transport and reactions in model liquids. In biological systems attention was focused on the following: excess electrons as probes of carcinogen electrophilicity; cost effectiveness of k{sub e} as a carcinogen-screening test; and conversion of k{sub e} to a carcinogen-screening electronic device. In model liquids, research was focused on two areas. The first investigated radiation-induced dimerization of fullerenes. The second area studied radiolytic synthesis of fullerene derivatives.

  3. Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry: Mechanistic Studies and Methods for Improving the Structural Identification of Carbohydrates

    PubMed Central

    Lai, Yin-Hung; Wang, Yi-Sheng

    2017-01-01

    Although matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is one of the most widely used soft ionization methods for biomolecules, the lack of detailed understanding of ionization mechanisms restricts its application in the analysis of carbohydrates. Structural identification of carbohydrates achieved by MALDI mass spectrometry helps us to gain insights into biological functions and pathogenesis of disease. In this review, we highlight mechanistic details of MALDI, including both ionization and desorption. Strategies to improve the ion yield of carbohydrates are also reviewed. Furthermore, commonly used fragmentation methods to identify the structure are discussed. PMID:28959517

  4. Effects of ionizing and non-ionizing radiation on the growth and development of plants. Final report, May 1959-November 1982

    SciTech Connect

    Klein, W.H.

    1985-01-01

    A summary of research to investigate the effects of ionizing and non-ionizing radiation on the growth and development of plants is presented. Included in this report are summaries of studies on the interaction of visible radiant energy with x-ray-induced chromosomal aberrations, an investigation of the biochemical and biophysical mechanisms by which plants detect and react to external radiation across the electromagnetic spectrum and a description of precise and sophisticated instruments that were designed and developed to continuously monitor the composition of that radiation in the environment. 69 refs.

  5. Advanced radioactive waste assay methods: Final report

    SciTech Connect

    Cline, J.E.; Robertson, D.E.; DeGroot, S.E.

    1987-11-01

    This report describes an evaluation of advanced methodologies for the radioassay of low power-plant low-level radioactive waste for compliance with the 10CFR61 classification rules. The project evaluated current assay practices in ten operating plants and identified areas where advanced methods would apply, studied two direct-assay methodologies, demonstrated these two techniques on radwaste in four operating plants and on irradiated components in two plants, and developed techniques for obtaining small representative aliquots from larger samples and for enhancing the /sup 144/Ce activity analysis in samples of waste. The study demonstrated the accuracy, practicality, and ALARA aspects of advanced methods and indicates that cost savings, resulting from the accuracy improvement and reduction in sampling requirements can be significant. 24 refs., 60 figs., 67 tabs.

  6. A novel method involving Matlab coding to determine the distribution of a collimated ionizing radiation beam

    NASA Astrophysics Data System (ADS)

    Ioan, M.-R.

    2016-08-01

    In ionizing radiation related experiments, precisely knowing of the involved parameters it is a very important task. Some of these experiments are involving the use of electromagnetic ionizing radiation such are gamma rays and X rays, others make use of energetic charged or not charged small dimensions particles such are protons, electrons, neutrons and even, in other cases, larger accelerated particles such are helium or deuterium nuclei are used. In all these cases the beam used to hit an exposed target must be previously collimated and precisely characterized. In this paper, a novel method to determine the distribution of the collimated beam involving Matlab coding is proposed. The method was implemented by using of some Pyrex glass test samples placed in the beam where its distribution and dimension must be determined, followed by taking high quality pictures of them and then by digital processing the resulted images. By this method, information regarding the doses absorbed in the exposed samples volume are obtained too.

  7. Halocarbon refrigerant detection methods. Final report

    SciTech Connect

    Tapscott, R.E.; Sohn, C.W.

    1996-01-01

    The Montreal Protocol and the U.S. Clean Air Act limit the production of ozone-depleting substances, including many refrigerants. Three options for cost-effectively phasing out these refrigerants from Army installations are: (1) refrigerant containment, (2) retrofit conversion to accommodate alternative refrigerant, and (3) replacement with cooling systems using alternative refrigerant. This report contributes to the first option by identifying and assessing methods to detect chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC) and hydrofluorocarbon (HFC) refrigerants that leak from air-conditioning and refrigeration systems. As background, the report describes the relevant sections of the Montreal Protocol and the Clean Air Act, and gives an overview of refrigerants. This is followed by a description of the technologies used in refrigerant leak detection, and a survey of detector types available and their price ranges. Appendixes provide an extensive list of detector products and their specifications, plus manufacturer addresses and phone numbers.

  8. A multiple ion counter total evaporation (MICTE) method for precise analysis of plutonium by thermal ionization mass spectrometry

    DOE PAGES

    Inglis, Jeremy D.; Maassen, Joel; Kara, Azim; ...

    2017-04-28

    This study presents a total evaporation method for the analysis of sub-picogram quantities of Pu, utilizing an array of multiple ion counters. Data from three standards are presented to assess the utility of the technique. An external precision of 1.5% RSD (2σ) was achieved on aliquots approaching 100 fg for the minor 240Pu isotope. Accurate analysis of <1 femtogram of 240Pu, is achievable, with an external reproducibility of better than 10% RSD (2σ). Finally, this new technique represents a significant advance in the total evaporation method and will allow routine measurement of femtogram sized Pu samples by thermal ionization massmore » spectrometry.« less

  9. Equation of motion coupled cluster methods for electron attachment and ionization potential in polyacenes

    SciTech Connect

    Bhaskaran-Nair, Kiran; Kowalski, Karol; Jarrell, Mark; Moreno, Juana; Shelton, William A.

    2015-11-05

    Polyacenes have attracted considerable attention due to their use in organic based optoelectronic materials. Polyacenes are polycyclic aromatic hydrocarbons composed of fused benzene rings. Key to understanding and design of new functional materials is an understanding of their excited state properties starting with their electron affinity (EA) and ionization potential (IP). We have developed a highly accurate and com- putationally e*fficient EA/IP equation of motion coupled cluster singles and doubles (EA/IP-EOMCCSD) method that is capable of treating large systems and large basis set. In this study we employ the EA/IP-EOMCCSD method to calculate the electron affinity and ionization potential of naphthalene, anthracene, tetracene, pentacene, hex- acene and heptacene. We have compared our results with other previous theoretical studies and experimental data. Our EA/IP results are in very good agreement with experiment and when compared with the other theoretical investigations our results represent the most accurate calculations as compared to experiment.

  10. Direct Delta-MBPT(2) method for ionization potentials, electron affinities, and excitation energies using fractional occupation numbers

    SciTech Connect

    Beste, Ariana; Vazquez-Mayagoitia, Alvaro; Ortiz, J. Vincent

    2013-01-01

    A direct method (D-Delta-MBPT(2)) to calculate second-order ionization potentials (IPs), electron affinities (EAs), and excitation energies is developed. The Delta-MBPT(2) method is defined as the correlated extension of the Delta-HF method. Energy differences are obtained by integrating the energy derivative with respect to occupation numbers over the appropriate parameter range. This is made possible by writing the second-order energy as a function of the occupation numbers. Relaxation effects are fully included at the SCF level. This is in contrast to linear response theory, which makes the D-Delta-MBPT(2) applicable not only to single excited but also higher excited states. We show the relationship of the D-Delta-MBPT(2) method for IPs and EAs to a second-order approximation of the effective Fock-space coupled-cluster Hamiltonian and a second-order electron propagator method. We also discuss the connection between the D-Delta-MBPT(2) method for excitation energies and the CIS-MP2 method. Finally, as a proof of principle, we apply our method to calculate ionization potentials and excitation energies of some small molecules. For IPs, the Delta-MBPT(2) results compare well to the second-order solution of the Dyson equation. For excitation energies, the deviation from EOM-CCSD increases when correlation becomes more important. When using the numerical integration technique, we encounter difficulties that prevented us from reaching the Delta-MBPT(2) values. Most importantly, relaxation beyond the Hartree Fock level is significant and needs to be included in future research.

  11. Analysis of omnoponum by surface-ionization mass spectrometry and liquid chromatography tandem mass spectrometry methods.

    PubMed

    Usmanov, Dilshadbek; Khasanov, Usman; Pantsirev, Aleksey; Van Bocxlaer, Jan

    2010-12-01

    This paper provides the development of analytical capabilities of surface-ionization mass spectrometry (SI/MS) and high performance liquid chromatography with tandem mass spectrometry (HPLC/MS/MS) for narcotic analgesic omnoponum, which perfectly exemplifies a mixture of opium alkaloids. It has been revealed that the investigated opiates solution, omnoponum, is ionized by the surface ionization (SI) method with high sensitivity. In the SI mass spectrum, M+, (M-H)+, (M-H-2nH)+, (M-R)+ and (M-R-2nH)+ ion lines, where M is a molecule, H is the hydrogen atom and R is a radical, were observed. These ion lines consist of combined omnoponum mixture SI mass spectra, i.e. morphine, codeine, thebaine, papaverine, and narcotine. Moreover, while the study of omnoponum by HPLC/MS/MS methods has attested that the mixture really consists of 5 components, it has been demonstrated that the SI/MS method can be utilized for the analysis of this mixture without the necessity of its chromatographic separation. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  12. On the accuracy of density functional theory and wave function methods for calculating vertical ionization energies

    SciTech Connect

    McKechnie, Scott; Booth, George H.; Cohen, Aron J.; Cole, Jacqueline M.

    2015-05-21

    The best practice in computational methods for determining vertical ionization energies (VIEs) is assessed, via reference to experimentally determined VIEs that are corroborated by highly accurate coupled-cluster calculations. These reference values are used to benchmark the performance of density functional theory (DFT) and wave function methods: Hartree-Fock theory, second-order Møller-Plesset perturbation theory, and Electron Propagator Theory (EPT). The core test set consists of 147 small molecules. An extended set of six larger molecules, from benzene to hexacene, is also considered to investigate the dependence of the results on molecule size. The closest agreement with experiment is found for ionization energies obtained from total energy difference calculations. In particular, DFT calculations using exchange-correlation functionals with either a large amount of exact exchange or long-range correction perform best. The results from these functionals are also the least sensitive to an increase in molecule size. In general, ionization energies calculated directly from the orbital energies of the neutral species are less accurate and more sensitive to an increase in molecule size. For the single-calculation approach, the EPT calculations are in closest agreement for both sets of molecules. For the orbital energies from DFT functionals, only those with long-range correction give quantitative agreement with dramatic failing for all other functionals considered. The results offer a practical hierarchy of approximations for the calculation of vertical ionization energies. In addition, the experimental and computational reference values can be used as a standardized set of benchmarks, against which other approximate methods can be compared.

  13. On the accuracy of density functional theory and wave function methods for calculating vertical ionization energies

    NASA Astrophysics Data System (ADS)

    McKechnie, Scott; Booth, George H.; Cohen, Aron J.; Cole, Jacqueline M.

    2015-05-01

    The best practice in computational methods for determining vertical ionization energies (VIEs) is assessed, via reference to experimentally determined VIEs that are corroborated by highly accurate coupled-cluster calculations. These reference values are used to benchmark the performance of density functional theory (DFT) and wave function methods: Hartree-Fock theory, second-order Møller-Plesset perturbation theory, and Electron Propagator Theory (EPT). The core test set consists of 147 small molecules. An extended set of six larger molecules, from benzene to hexacene, is also considered to investigate the dependence of the results on molecule size. The closest agreement with experiment is found for ionization energies obtained from total energy difference calculations. In particular, DFT calculations using exchange-correlation functionals with either a large amount of exact exchange or long-range correction perform best. The results from these functionals are also the least sensitive to an increase in molecule size. In general, ionization energies calculated directly from the orbital energies of the neutral species are less accurate and more sensitive to an increase in molecule size. For the single-calculation approach, the EPT calculations are in closest agreement for both sets of molecules. For the orbital energies from DFT functionals, only those with long-range correction give quantitative agreement with dramatic failing for all other functionals considered. The results offer a practical hierarchy of approximations for the calculation of vertical ionization energies. In addition, the experimental and computational reference values can be used as a standardized set of benchmarks, against which other approximate methods can be compared.

  14. On the accuracy of density functional theory and wave function methods for calculating vertical ionization energies.

    PubMed

    McKechnie, Scott; Booth, George H; Cohen, Aron J; Cole, Jacqueline M

    2015-05-21

    The best practice in computational methods for determining vertical ionization energies (VIEs) is assessed, via reference to experimentally determined VIEs that are corroborated by highly accurate coupled-cluster calculations. These reference values are used to benchmark the performance of density functional theory (DFT) and wave function methods: Hartree-Fock theory, second-order Møller-Plesset perturbation theory, and Electron Propagator Theory (EPT). The core test set consists of 147 small molecules. An extended set of six larger molecules, from benzene to hexacene, is also considered to investigate the dependence of the results on molecule size. The closest agreement with experiment is found for ionization energies obtained from total energy difference calculations. In particular, DFT calculations using exchange-correlation functionals with either a large amount of exact exchange or long-range correction perform best. The results from these functionals are also the least sensitive to an increase in molecule size. In general, ionization energies calculated directly from the orbital energies of the neutral species are less accurate and more sensitive to an increase in molecule size. For the single-calculation approach, the EPT calculations are in closest agreement for both sets of molecules. For the orbital energies from DFT functionals, only those with long-range correction give quantitative agreement with dramatic failing for all other functionals considered. The results offer a practical hierarchy of approximations for the calculation of vertical ionization energies. In addition, the experimental and computational reference values can be used as a standardized set of benchmarks, against which other approximate methods can be compared.

  15. On the accuracy of density functional theory and wave function methods for calculating vertical ionization energies.

    SciTech Connect

    McKechnie, Scott; Booth, George H.; Cohen, Aron J.; Cole, Jacqueline M.

    2015-05-21

    The best practice in computational methods for determining vertical ionization energies (VIEs) is assessed, via reference to experimentally determined VIEs that are corroborated by highly accurate coupled-cluster calculations. These reference values are used to benchmark the performance of density-functional theory (DFT) and wave function methods: Hartree-Fock theory (HF), second-order Møller-Plesset perturbation theory (MP2) and Electron Propagator Theory (EPT). The core test set consists of 147 small molecules. An extended set of six larger molecules, from benzene to hexacene, is also considered to investigate the dependence of the results on molecule size. The closest agreement with experiment is found for ionization energies obtained from total energy diff calculations. In particular, DFT calculations using exchange-correlation functionals with either a large amount of exact exchange or long-range correction perform best. The results from these functionals are also the least sensitive to an increase in molecule size. In general, ionization energies calculated directly from the orbital energies of the neutral species are less accurate and more sensitive to an increase in molecule size. For the single-calculation approach, the EPT calculations are in closest agreement for both sets of molecules. For the orbital energies from DFT functionals, only those with long-range correction give quantitative agreement with dramatic failing for all other functionals considered. The results offer a practical hierarchy of approximations for the calculation of vertical ionization energies. In addition, the experimental and computational reference values can be used as a standardized set of benchmarks, against which other approximate methods can be compared.

  16. Dissociation and dissociative ionization of H2+ using the time-dependent surface flux method

    NASA Astrophysics Data System (ADS)

    Yue, Lun; Madsen, Lars Bojer

    2013-12-01

    The time-dependent surface flux method developed for the description of electronic spectra L. Tao and A. Scrinzi, New J. Phys. 14, 013021 (2012), 10.1088/1367-2630/14/1/013021; A. Scrinzi, New J. Phys. 14, 085008 (2012), 10.1088/1367-2630/14/8/085008] is extended to treat dissociation and dissociative ionization processes of H2+ interacting with strong laser pulses. By dividing the simulation volume into proper spatial regions associated with the individual reaction channels and monitoring the probability flux, the joint energy spectrum for the dissociative ionization process and the energy spectrum for dissociation is obtained. The methodology is illustrated by solving the time-dependent Schrödinger equation for a collinear one-dimensional model of H2+ with electronic and nuclear motions treated exactly and validated by comparison with published results for dissociative ionization. The results for dissociation are qualitatively explained by analysis based on dressed diabatic Floquet potential energy curves, and the method is used to investigate the breakdown of the two-surface model.

  17. A novel benzene quantitative analysis method using miniaturized metal ionization gas sensor and non-linear bistable dynamic system

    PubMed Central

    Tang, Xuxiang; Liu, Fuqi

    2015-01-01

    In this paper, a novel benzene quantitative analysis method utilizing miniaturized metal ionization gas sensor and non-linear bistable dynamic system was investigated. Al plate anodic gas-ionization sensor was installed for electrical current-voltage data measurement. Measurement data was analyzed by non-linear bistable dynamics system. Results demonstrated that this method realized benzene concentration quantitative determination. This method is promising in laboratory safety management in benzene leak detection. PMID:26218927

  18. A novel benzene quantitative analysis method using miniaturized metal ionization gas sensor and non-linear bistable dynamic system.

    PubMed

    Tang, Xuxiang; Liu, Fuqi

    2015-01-01

    In this paper, a novel benzene quantitative analysis method utilizing miniaturized metal ionization gas sensor and non-linear bistable dynamic system was investigated. Al plate anodic gas-ionization sensor was installed for electrical current-voltage data measurement. Measurement data was analyzed by non-linear bistable dynamics system. Results demonstrated that this method realized benzene concentration quantitative determination. This method is promising in laboratory safety management in benzene leak detection.

  19. Reducing the dimensionality of grid based methods for electron-atom scattering calculations below ionization threshold

    NASA Astrophysics Data System (ADS)

    Benda, Jakub; Houfek, Karel

    2017-04-01

    For total energies below the ionization threshold it is possible to dramatically reduce the computational burden of the solution of the electron-atom scattering problem based on grid methods combined with the exterior complex scaling. As in the R-matrix method, the problem can be split into the inner and outer problem, where the outer problem considers only the energetically accessible asymptotic channels. The (N + 1)-electron inner problem is coupled to the one-electron outer problems for every channel, resulting in a matrix that scales only linearly with size of the outer grid.

  20. Apparatus and method for the simultaneous detection of neutrons and ionizing electromagnetic radiation

    DOEpatents

    Bell, Zane W.

    2000-01-01

    A sensor for simultaneously detecting neutrons and ionizing electromagnetic radiation comprising: a sensor for the detection of gamma radiation, the sensor defining a sensing head; the sensor further defining an output end in communication with the sensing head; and an exterior neutron-sensitive material configured to form around the sensing head; wherein the neutron-sensitive material, subsequent to the capture of the neutron, fissions into an alpha-particle and a .sup.7 Li ion that is in a first excited state in a majority of the fissions, the first excited state decaying via the emission of a single gamma ray at 478 keV which can in turn be detected by the sensing head; and wherein the sensing head can also detect the ionizing electromagnetic radiation from an incident radiation field without significant interference from the neutron-sensitive material. A method for simultaneously detecting neutrons and ionizing electromagnetic radiation comprising the steps of: providing a gamma ray sensitive detector comprising a sensing head and an output end; conforming an exterior neutron-sensitive material configured to form around the sensing head of the detector; capturing neutrons by the sensing head causing the neutron-sensitive material to fission into an alpha-particle and a .sup.7 Li ion that is in a first excited state in a majority of the fissions, the state decaying via the emission of a single gamma ray at 478 keV; sensing gamma rays entering the detector through the neutron-sensitive material; and producing an output through a readout device coupled to the output end; wherein the detector provides an output which is proportional to the energy of the absorbed ionizing electromagnetic radiation.

  1. Higher-Order Equation-of-Motion Coupled-Cluster Methods for Ionization Processes

    SciTech Connect

    Kamiya, Muneaki; Hirata, So

    2006-08-21

    Compact algebraic equations defining the equation-of-motion coupled-cluster (EOM-CC) methods for ionization potentials (IP-EOM-CC) have been derived and computer implemented by virtue of a symbolic algebra system largely automating these processes. Models with connected cluster excitation operators truncated after double, triple, or quadruple level and with linear ionization operators truncated after two-hole-one-particle (2h1p), three-hole-two-particle (3h2p), or four-hole-three-particle (4h3p) level (abbreviated as IP-EOM-CCSD, CCSDT, and CCSDTQ, respectively) have been realized into parallel algorithms taking advantage of spin, spatial, and permutation symmetries with optimal size dependence of the computational costs. They are based on spin-orbital formalisms and can describe both {alpha} and {beta} and ionizations from open-shell (doublet, triplet, etc.) reference states into ionized states with various spin magnetic quantum numbers. The application of these methods to Koopmans and satellite ionizations of N{sub 2} and CO (with the ambiguity due to finite basis sets eliminated by extrapolation) has shown that IP-EOM-CCSD frequently accounts for orbital relaxation inadequately and displays errors exceeding a couple of eV. However, these errors can be systematically reduced to tenths or even hundredths of an eV by IP-EOM-CCSDT or CCSDTQ. Comparison of spectroscopic parameters of the FH{sup +} and NH{sup +} radicals between IP-EOM-CC and experiments has also underscored the importance of higher-order IP-EOM-CC treatments. For instance, the harmonic frequencies of the {tilde A} {sup 2}{Sigma}{sup -} state of NH{sup +}+ are predicted to be 1285, 1723, and 1705 cm{sup -1} by IP-EOM-CCSD, CCSDT, and CCSDTQ, respectively, as compared to the observed value of 1707 cm{sup -1}. The small adiabatic energy separation (observed 0.04 eV) between the {tilde X} {sup 2}II and {tilde a} {sup 4}{sigma}{sup -} states of NH{sup +} also requires IP-EOM-CCSDTQ for a quantitative

  2. Experimental and theoretical triple differential cross sections for electron-impact ionization of Ar (3p) for equal energy final state electrons

    NASA Astrophysics Data System (ADS)

    Amami, Sadek; Ozer, Zehra N.; Dogan, Mevlut; Yavuz, Murat; Varol, Onur; Madison, Don

    2016-09-01

    There have been several studies of electron-impact ionization of inert gases for asymmetric final state energy sharing and normally one electron has an energy significantly higher than the other. However, there have been relatively few studies examining equal energy final state electrons. Here we report experimental and theoretical triple differential cross sections for electron impact ionization of Ar (3p) for equal energy sharing of the outgoing electrons. Previous experimental results combined with some new measurements are compared with distorted wave born approximation (DWBA) results, DWBA results using the Ward-Macek (WM) approximation for the post collision interaction (PCI), and three-body distorted wave (3DW) which includes PCI without approximation. The results show that it is crucially important to include PCI in the calculation particularly for lower energies and that the WM approximation is valid only for high energies. The 3DW, on the other hand, is in reasonably good agreement with data down to fairly low energies.

  3. Comparison of pencil-type ionization chamber calibration results and methods between dosimetry laboratories.

    PubMed

    Hourdakis, Costas J; Büermann, Ludwig; Ciraj-Bjelac, Olivera; Csete, Istvan; Delis, Harry; Gomola, Igor; Persson, Linda; Novak, Leos; Petkov, Ivailo; Toroi, Paula

    2016-01-01

    A comparison of calibration results and procedures in terms of air kerma length product, PKL, and air kerma, K, was conducted between eight dosimetry laboratories. A pencil-type ionization chamber (IC), generally used for computed tomography dose measurements, was calibrated according to three calibration methods, while its residual signal and other characteristics (sensitivity profile, active length) were assessed. The results showed that the "partial irradiation method" is the preferred method for the pencil-type IC calibration in terms of PKL and it could be applied by the calibration laboratories successfully. Most of the participating laboratories achieved high level of agreement (>99%) for both dosimetry quantities (PKL and K). Estimated relative standard uncertainties of comparison results vary among laboratories from 0.34% to 2.32% depending on the quantity, beam quality and calibration method applied. Detailed analysis of the assigned uncertainties have been presented and discussed.

  4. Calculations of molecular ionization energies using a self-consistent-charge Hartree-Fock-Slater method

    NASA Technical Reports Server (NTRS)

    Rosen, A.; Ellis, D. E.; Adachi, H.; Averill, F. W.

    1976-01-01

    A numerical-variational method for performing self-consistent molecular calculations in the Hartree-Fock-Slater (HFS) model is presented. Molecular wavefunctions are expanded in terms of basis sets constructed from numerical HFS solutions of selected one-center atomlike problems. Binding energies and wavefunctions for the molecules are generated using a discrete variational method for a given molecular potential. In the self-consistent-charge (SCC) approximation to the complete self-consistent-field (SCF) method, results of a Mulliken population analysis of the molecular eigenfunctions are used in each iteration to produce 'atomic' occupation numbers. The simplest SCC potential is then obtained from overlapping spherical atomlike charge distributions. Molecular ionization energies are calculated using the transition-state procedure; results are given for CO, H2O, H2S, AlCl, InCl, and the Ni5O surface complex. Agreement between experimental and theoretical ionization energies for the free-molecule valence levels is generally within 1 eV. The simple SCC procedure gives a reasonably good approximation to the molecular potential, as shown by comparison with experiment, and with complete SCF calculations for CO, H2O, and H2S.

  5. Does non-ionizing radiant energy affect determination of the evaporation rate by the gradient method?

    PubMed

    Kjartansson, S; Hammarlund, K; Oberg, P A; Sedin, G

    1991-01-01

    A study was performed to investigate whether measurements of the evaporation rate from the skin of newborn infants by the gradient method are affected by the presence of non-ionizing radiation from phototherapy equipment or a radiant heater. The evaporation rate was measured experimentally with the measuring sensors either exposed to or protected from non-ionizing radiation. Either blue light (phototherapy) or infrared light (radiant heater) was used; in the former case the evaporation rate was measured from a beaker of water covered with a semipermeable membrane, and in the latter case from the hand of an adult subject, aluminium foil or with the measuring probe in the air. No adverse effect on the determinations of the evaporation rate was found in the presence of blue light. Infrared radiation caused an error of 0.8 g/m2h when the radiant heater was set at its highest effect level or when the ambient humidity was high. At low and moderate levels the observed evaporation rate was not affected. It is concluded that when clinical measurements are made from the skin of newborn infants nursed under a radiant heater, the evaporation rate can appropriately be determined by the gradient method.

  6. Electron-impact ionization of diatomic molecules using a configuration-average distorted-wave method

    SciTech Connect

    Pindzola, M. S.; Robicheaux, F.; Colgan, J.; Ballance, C. P.

    2007-07-15

    Electron-impact ionization cross sections for diatomic molecules are calculated in a configuration-average distorted-wave method. Core bound orbitals for the molecular ion are calculated using a single-configuration self-consistent-field method based on a linear combination of Slater-type orbitals. The core bound orbitals are then transformed onto a two-dimensional (r,{theta}) numerical lattice from which a Hartree potential with local exchange is constructed. The single-particle Schroedinger equation is then solved for the valence bound orbital and continuum distorted-wave orbitals with S-matrix boundary conditions. Total cross section results for H{sub 2} and N{sub 2} are compared with those from semiempirical calculations and experimental measurements.

  7. Electrospray ionization-tandem mass spectrometry method for differentiating chlorine substitution in disinfection byproduct formation.

    PubMed

    Deng, Zhuo; Yang, Xin; Shang, Chii; Zhang, Xiangru

    2014-05-06

    An electrospray ionization-tandem mass spectrometry (ESI-tqMS) method was developed to identify the location of chlorine substitution during the chlorination of model organic compounds. The chlorine substitution in the aliphatic part and that in the benzene ring of an organic molecule can be differentiated by their corresponding ranges of optimum collision energies, 5-7 eV and over 15 eV, respectively, in the precursor ion scan of m/z 35. The method was applied to predict the structures of intermediates and reveal the transformation pathways during the chlorination of 4-amino-2-chlorobenzoic acid and phenylalanine as a function of reaction time and the chlorine-to-precursor ratio. In the case of phenylalanine, chlorine was found to replace one hydrogen atom attached to the aliphatic nitrogen; in the case of 4-amino-2-chlorobenzoic acid, chlorine was found to replace the hydrogen atoms attached to the aromatic rings.

  8. Electron impact total ionization cross sections for simple bio-molecules (H2CO, HCOOH and CH3COOH) using ICSP-ic method

    NASA Astrophysics Data System (ADS)

    Bhutadia, Harshad; Vinodkumar, Minaxi; Antony, Bobby

    2012-11-01

    In the present work we compute total ionization cross sections for simple bio-molecules viz. formaldehyde, formic acid and acetic acid on electron impact. The total ionization cross sections are extracted from total inelastic cross section using Improved Complex Scattering Potential-ionization contribution method.

  9. Valence ionization spectra of group six metal hexacarbonyls studied by the symmetry-adapted cluster-configuration interaction method.

    PubMed

    Fukuda, Ryoichi; Hayaki, Seigo; Nakatsuji, Hiroshi

    2009-11-07

    The valence ionization spectra up to 20 eV of group six metal carbonyls, chromium hexacarbonyl, molybdenum hexacarbonyl, and tungsten hexacarbonyl were studied by the symmetry-adapted cluster-configuration interaction (SAC-CI) method. The assignments of the spectra are given based on reliable SAC-CI calculations. The relativistic effects including the spin-orbit effects are important for the ionization spectrum of W(CO)(6). The relation between the metal-CO distance and ionization energies was examined. The lowest ionization energies of the three metal carbonyls are approximately the same because of the energy dependence of the metal-CO length and relativistic effects. In Cr(CO)(6), the Cr-CO interaction significantly increases the lowest ionization energy in comparison with Mo(CO)(6) and W(CO)(6) because of the relatively short metal-CO bond length. The relativistic effect reduces the lowest ionization energy of W(CO)(6) because the effective core potential of 5d electrons is more efficiently screened as a result of the relativistic contraction of the inner electrons.

  10. Determination of adiabatic ionization potentials and electron affinities of energetic molecules with the Gaussian-4 method

    NASA Astrophysics Data System (ADS)

    Manaa, M. Riad

    2017-06-01

    Adiabatic ionization potentials (IPad) and electron affinities (EAad) are determined with the Gaussian-4 (G4) method for the energetic molecules PETN, RDX, β-δ-HMX, CL-17, TNB, TNT, CL-14, DADNE, TNA, and TATB. The IPad and EAad values are in the range of 8.43-11.73 and 0.74-2.86 eV, respectively. Variations are due to substitutional effects of electron withdrawing and donating functional groups. Enthalpies of formation are also determined for several of these molecules to augment the list of recently reported G4 values. The calculated IPad and EAad provide quantitative assessment of such molecular properties as chemical hardness, molecular electronegativity, and ;intrinsic; molecular physical hardness.

  11. A rapid multidimensional GC-flame-ionization detector method for determination of fatty acid methyl esters.

    PubMed

    Xu, Yong-Jiang; Zhang, Jianbing

    2014-02-01

    Fatty acids play important roles in the pathogenesis of many diseases. In order to investigate a wide spectrum of fatty acids in biological matrix, we developed an approach for quantitative analysis of fatty acids based on a heart-cutting 2D gas chromatographic-flame ionization detector system. This system uses a Dean Switch interface between the primary polar and secondary nonpolar capillary column. Most of the standards were separated by the primary column. Unresolved components are selectively transferred to the secondary column, where they are completely separated. This method was further evaluated using plasma obtained from 11 healthy and 11 chronic coronary artery disease patients. Our results prove that this approach is sensitive, precise and specific, capable of measuring 37 specific fatty acids. It indicates that this approach offers a reliable and sensitive technical platform for comprehensive quantification of fatty acids.

  12. Application of the two-dose-rate method for general recombination correction for liquid ionization chambers in continuous beams

    NASA Astrophysics Data System (ADS)

    Andersson, Jonas; Tölli, Heikki

    2011-01-01

    A method to correct for the general recombination losses for liquid ionization chambers in continuous beams has been developed. The proposed method has been derived from Greening's theory for continuous beams and is based on measuring the signal from a liquid ionization chamber and an air filled monitor ionization chamber at two different dose rates. The method has been tested with two plane parallel liquid ionization chambers in a continuous radiation x-ray beam with a tube voltage of 120 kV and with dose rates between 2 and 13 Gy min-1. The liquids used as sensitive media in the chambers were isooctane (C8H18) and tetramethylsilane (Si(CH3)4). The general recombination effect was studied using chamber polarizing voltages of 100, 300, 500, 700 and 900 V for both liquids. The relative standard deviation of the results for the collection efficiency with respect to general recombination was found to be a maximum of 0.7% for isooctane and 2.4% for tetramethylsilane. The results are in excellent agreement with Greening's theory for collection efficiencies over 90%. The measured and corrected signals from the liquid ionization chambers used in this work are in very good agreement with the air filled monitor chamber with respect to signal to dose linearity.

  13. Application of the two-dose-rate method for general recombination correction for liquid ionization chambers in continuous beams.

    PubMed

    Andersson, Jonas; Tölli, Heikki

    2011-01-21

    A method to correct for the general recombination losses for liquid ionization chambers in continuous beams has been developed. The proposed method has been derived from Greening's theory for continuous beams and is based on measuring the signal from a liquid ionization chamber and an air filled monitor ionization chamber at two different dose rates. The method has been tested with two plane parallel liquid ionization chambers in a continuous radiation x-ray beam with a tube voltage of 120 kV and with dose rates between 2 and 13 Gy min(-1). The liquids used as sensitive media in the chambers were isooctane (C(8)H(18)) and tetramethylsilane (Si(CH(3))(4)). The general recombination effect was studied using chamber polarizing voltages of 100, 300, 500, 700 and 900 V for both liquids. The relative standard deviation of the results for the collection efficiency with respect to general recombination was found to be a maximum of 0.7% for isooctane and 2.4% for tetramethylsilane. The results are in excellent agreement with Greening's theory for collection efficiencies over 90%. The measured and corrected signals from the liquid ionization chambers used in this work are in very good agreement with the air filled monitor chamber with respect to signal to dose linearity.

  14. The computation of ionization potentials for second-row elements by ab initio and density functional theory methods

    SciTech Connect

    Jursic, B.S.

    1996-12-31

    Up to four ionization potentials of elements from the second-row of the periodic table were computed using the ab initio (HF, MP2, MP3, MP4, QCISD, GI, G2, and G2MP2) and DFT (B3LY, B3P86, B3PW91, XALPHA, HFS, HFB, BLYP, BP86, BPW91, BVWN, XAPLY, XAP86, XAPW91, XAVWN, SLYR SP86, SPW91 and SVWN) methods. In all of the calculations, the large 6-311++G(3df,3pd) gaussian type of basis set was used. The computed values were compared with the experimental results and suitability of the ab initio and DFF methods were discussed, in regard to reproducing the experimental data. From the computed ionization potentials of the second-row elements, it can be concluded that the HF ab initio computation is not capable of reproducing the experimental results. The computed ionization potentials are too low. However, by using the ab initio methods that include electron correlation, the computed IPs are becoming much closer to the experimental values. In all cases, with the exception of the first ionization potential for oxygen, the G2 computation result produces ionization potentials that are indistinguishable from the experimental results.

  15. The feasibility of epidemiologic investigations of the health effects of low-level ionizing radiation. Final report, 3 July 1979-30 October 1980

    SciTech Connect

    Dreyer, N.A.; Kohn, H.I.; Clapp, R.W.; Covino, S.J. Jr.; Fahey, F.H.

    1980-11-01

    This is the final report of 'A Study to Determine the Feasibility of Conducting Epidemiologic Investigations of the Health Effects of Low-Level Ionizing Radiation', begun July 3, 1979. The study defines low-level ionizing radiation as a single dose of 5 rem (whole-body) or less and chronic doses that accumulate at the rate of less than 5 rem per year. The objective of this project was to determine whether or not further epidemiologic research (either expansion of current projects or initiation of new ones) would be useful at this time for quantitating the health effects due to low-level ionizing radiation. No outstanding candidate population is recommended for study since, even if the largest available populations are studied, the chance of finding a definite positive result is very small. However, the decision to conduct a study must rest heavily on social and political considerations rather than on purely scientific ones. Therefore, four populations are tentatively proposed for prospective cohort studies, with nested case-control studies as needed. Overall, the most practical approach would be to conduct a study through a national worker registry, with cancer as the endpoint of interest.

  16. Developments in FT-ICR MS instrumentation, ionization techniques, and data interpretation methods for petroleomics.

    PubMed

    Cho, Yunju; Ahmed, Arif; Islam, Annana; Kim, Sunghwan

    2015-01-01

    Because of the increasing importance of heavy and unconventional crude oil as an energy source, there is a growing need for petroleomics: the pursuit of more complete and detailed knowledge of the chemical compositions of crude oil. Crude oil has an extremely complex nature; hence, techniques with ultra-high resolving capabilities, such as Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), are necessary. FT-ICR MS has been successfully applied to the study of heavy and unconventional crude oils such as bitumen and shale oil. However, the analysis of crude oil with FT-ICR MS is not trivial, and it has pushed analysis to the limits of instrumental and methodological capabilities. For example, high-resolution mass spectra of crude oils may contain over 100,000 peaks that require interpretation. To visualize large data sets more effectively, data processing methods such as Kendrick mass defect analysis and statistical analyses have been developed. The successful application of FT-ICR MS to the study of crude oil has been critically dependent on key developments in FT-ICR MS instrumentation and data processing methods. This review offers an introduction to the basic principles, FT-ICR MS instrumentation development, ionization techniques, and data interpretation methods for petroleomics and is intended for readers having no prior experience in this field of study. © 2014 Wiley Periodicals, Inc.

  17. Biological dosimeter for cellular damage and repair by ionizing radiation. Final technical progress report, May 1, 1993--April 30, 1996

    SciTech Connect

    Cress, A.E.

    1998-06-30

    The authors have investigated the alteration of chromatin domains in Human T and B cells after ionizing radiation using three DNA specific dyes, Feulgen, Hoechst and 7-amino actinomycin D. Characterization and differentiation of T and B cells was accomplished using only 4 of a possible 32 image features with the CAS and Quaritex QX7 Digital Image Systems. Human B and T cells were irradiated with 1, 5 and 10 Gy and analyzed during a 1.5 hour recovery period. The chosen features detect a dose dependent change in DNA domains which can be observed as early as 1.5 hours after a 1Gv exposure. The results suggest that the ability of DNA specific dyes to stain chromatin can be used as an early sensitive indicator of DNA damage. The observed alteration of chromatin staining suggests that chromatin structure does observably change in a significant manner during a DNA repair interval. Since these alteration can be detected with DNA specific dyes that stain both AT rich, GC rich or total DNA, these data suggest that a global alteration of the chromatin is occurring after exposure to ionizing radiation.

  18. A two-dose-rate method for general recombination correction for liquid ionization chambers in pulsed beams

    NASA Astrophysics Data System (ADS)

    Tölli, Heikki; Sjögren, Rickard; Wendelsten, Mikael

    2010-08-01

    The correction for general recombination losses in liquid ionization chambers (LICs) is more complex than that in air-filled ionization chambers. The reason for this is that the saturation charge in LICs, i.e. the charge that escapes initial recombination, depends on the applied voltage. This paper presents a method, based on measurements at two different dose rates in a pulsed beam, for general recombination correction in LICs. The Boag theory for pulsed beams is used and the collection efficiency is determined by numerical methods which are equivalent to the two-voltage method used in dosimetry with air-filled ionization chambers. The method has been tested in experiments in water in a 20 MeV electron beam using two LICs filled with isooctane and tetramethylsilane. The dose per pulse in the electron beam was varied between 0.1 mGy/pulse and 8 mGy/pulse. The relative standard deviations of the collection efficiencies determined with the two-dose-rate method ranged between 0.1% and 1.5%. The dose-rate variations of the general recombination corrected charge measured with the LICs are in excellent agreement with the corresponding values obtained with an air-filled plane parallel ionization chamber.

  19. Modeling ion recombination in liquid ionization chambers - Improvement and analysis of the two-dose-rate method.

    PubMed

    Andersson, Jonas; Tölli, Heikki

    2017-08-12

    The use of liquid ionization chambers can provide useful information to endeavors with radiation dosimetry for highly modulated beams. Liquid ionization chambers may be particularly suitable for computed tomography applications where conventional ionization chambers do not present a high enough sensitivity for the spatial resolution required to characterize common X-ray beams. Due to the sensitivity, which leads to high charge densities, liquid ionization chambers can suffer from large recombination losses leading to degradation in signal to dose rate linearity. To solve this problem, a two-dose-rate method for general recombination correction has been proposed for liquid ionization chambers. However, the valid range of recombination losses that the method can accurately account for has been found to vary depending on radiation quality. The present work provides an in-depth analysis of the performance of the two-dose-rate method. Furthermore, the soundness of applying gas theory to liquids is investigated by using the two-dose-rate method. In the present work, the two-dose-rate method for general recombination correction of liquid ionization chambers used in continuous beams is studied by employing theory for gas-filled ionization chambers. An approximate relation for the general collection efficiency containing a material-specific parameter that is traceable to liquids has been derived for theoretical and experimental investigation alongside existing theory. Furthermore, the disassociation between initial and general recombination in the method is analyzed both theoretically and experimentally. The results indicate that liquids and gases share general recombination characteristics, where the liquids investigated (isooctane and tetramethylsilane) to a large extent mimic the behavior theoretically expected in gases. Furthermore, it is shown that the disassociation between initial and general recombination in the two-dose-rate method is an approximation that depends

  20. Effects of Ionizing Radiation on Biological Molecules—Mechanisms of Damage and Emerging Methods of Detection

    PubMed Central

    Reisz, Julie A.; Bansal, Nidhi; Qian, Jiang; Zhao, Weiling

    2014-01-01

    Abstract Significance: The detrimental effects of ionizing radiation (IR) involve a highly orchestrated series of events that are amplified by endogenous signaling and culminating in oxidative damage to DNA, lipids, proteins, and many metabolites. Despite the global impact of IR, the molecular mechanisms underlying tissue damage reveal that many biomolecules are chemoselectively modified by IR. Recent Advances: The development of high-throughput “omics” technologies for mapping DNA and protein modifications have revolutionized the study of IR effects on biological systems. Studies in cells, tissues, and biological fluids are used to identify molecular features or biomarkers of IR exposure and response and the molecular mechanisms that regulate their expression or synthesis. Critical Issues: In this review, chemical mechanisms are described for IR-induced modifications of biomolecules along with methods for their detection. Included with the detection methods are crucial experimental considerations and caveats for their use. Additional factors critical to the cellular response to radiation, including alterations in protein expression, metabolomics, and epigenetic factors, are also discussed. Future Directions: Throughout the review, the synergy of combined “omics” technologies such as genomics and epigenomics, proteomics, and metabolomics is highlighted. These are anticipated to lead to new hypotheses to understand IR effects on biological systems and improve IR-based therapies. Antioxid. Redox Signal. 21: 260–292. PMID:24382094

  1. Computation of axisymmetric and ionized flows using particle and continuum methods

    NASA Technical Reports Server (NTRS)

    Boyd, Iain D.; Gokcen, Tahir

    1993-01-01

    Comparisons between particle and continuum simulations of hypersonic near-continuum flows are presented. The particle approach employs the direct simulation Monte Carlo method (DSMC), and the continuum approach solves the Euler equations. Both simulations have thermochemistry models for air implemented including ionization. A new axisymmetric DSMC code which is efficiently vectorized is developed for this study. In this DSMC code, particular attention is paid to matching the relaxation rates employed in the continuum approach. This investigation represents a continuation of a previous study which considered thermochemical relaxation in one-dimensional shock waves of nitrogen. Comparison of the particle and continuum methods is first made for an axisymmetric blunt-body flow of air at 7 km/s. Very good agreement is obtained for the two solutions. The two techniques also compare well for a one-dimensional shock wave in air at 10 km/s. In both applications, the results are found to be sensitive to various aspects of the chemistry models employed.

  2. Computation of axisymmetric and ionized hypersonic flows using particle and continuum methods

    NASA Technical Reports Server (NTRS)

    Boyd, Iain D.; Gokcen, Tahir

    1994-01-01

    Comparisons between particle and continuum simulations of hypersonic near-continuum flows are presented. The particle approach employs the direct simulation Monte Carlo (DSMC) method, and the continuum approach solves the appropriate equations of fluid flow. Both simulations have thermochemistry models for air implemented including ionization. A new axisymmetric DSMC code that is efficiently vectorized is developed for this study. In this DSMC code, particular attention is paid to matching the relaxation rates employed in the continuum approach. This investigation represents a continuum of a previous study that considered thermochemical relaxation in one-dimensional shock waves of nitrogen. Comparison of the particle and continuum methods is first made for an axisymmetric blunt-body flow of air at 7 km/s. Very good agreement is obtained for the two solutions. The two techniques also compare well for a one-dimensional shock wave in air at 10 km/s. In both applications, the results are found to be sensitive to various aspects of the chemistry model employed.

  3. Computation of axisymmetric and ionized flows using particle and continuum methods

    NASA Technical Reports Server (NTRS)

    Boyd, Iain D.; Gokcen, Tahir

    1993-01-01

    Comparisons between particle and continuum simulations of hypersonic near-continuum flows are presented. The particle approach employs the direct simulation Monte Carlo method (DSMC), and the continuum approach solves the Euler equations. Both simulations have thermochemistry models for air implemented including ionization. A new axisymmetric DSMC code which is efficiently vectorized is developed for this study. In this DSMC code, particular attention is paid to matching the relaxation rates employed in the continuum approach. This investigation represents a continuation of a previous study which considered thermochemical relaxation in one-dimensional shock waves of nitrogen. Comparison of the particle and continuum methods is first made for an axisymmetric blunt-body flow of air at 7 km/s. Very good agreement is obtained for the two solutions. The two techniques also compare well for a one-dimensional shock wave in air at 10 km/s. In both applications, the results are found to be sensitive to various aspects of the chemistry models employed.

  4. Computation of axisymmetric and ionized hypersonic flows using particle and continuum methods

    NASA Technical Reports Server (NTRS)

    Boyd, Iain D.; Gokcen, Tahir

    1994-01-01

    Comparisons between particle and continuum simulations of hypersonic near-continuum flows are presented. The particle approach employs the direct simulation Monte Carlo (DSMC) method, and the continuum approach solves the appropriate equations of fluid flow. Both simulations have thermochemistry models for air implemented including ionization. A new axisymmetric DSMC code that is efficiently vectorized is developed for this study. In this DSMC code, particular attention is paid to matching the relaxation rates employed in the continuum approach. This investigation represents a continuum of a previous study that considered thermochemical relaxation in one-dimensional shock waves of nitrogen. Comparison of the particle and continuum methods is first made for an axisymmetric blunt-body flow of air at 7 km/s. Very good agreement is obtained for the two solutions. The two techniques also compare well for a one-dimensional shock wave in air at 10 km/s. In both applications, the results are found to be sensitive to various aspects of the chemistry model employed.

  5. Simulation of thermal ionization in a dense helium plasma by the Feynman path integral method

    NASA Astrophysics Data System (ADS)

    Shevkunov, S. V.

    2011-04-01

    The region of equilibrium states is studied where the quantum nature of the electron component and a strong nonideality of a plasma play a key role. The problem of negative signs in the calculation of equilibrium averages a system of indistinguishable quantum particles with a spin is solved in the macroscopic limit. It is demonstrated that the calculation can be conducted up to a numerical result. The complete set of symmetrized basis wave functions is constructed based on the Young symmetry operators. The combinatorial weight coefficients of the states corresponding to different graphs of connected Feynman paths in multiparticle systems are calculated by the method of random walk over permutation classes. The kinetic energy is calculated using a viral estimator at a finite pressure in a statistical ensemble with flexible boundaries. Based on the methods developed in the paper, the computer simulation is performed for a dense helium plasma in the temperature range from 30000 to 40000 K. The equation of state, internal energy, ionization degree, and structural characteristic of the plasma are calculated in terms of spatial correlation functions. The parameters of a pseudopotential plasma model are estimated.

  6. [New dosimetry system based on the thermoluminescence method for evaluation of ionizing radiation doses to workers of the health centers].

    PubMed

    Urban, Paweł; Skubacz, Krystian

    2015-01-01

    In different areas of industry, science and in the greater extend medicine, plenty of devices intended for production of ionizing radiation or containing sources of such radiation found application. Such situation causes the necessity to control such kind of hazards. Currently, the most popular technique for detection of ionizing radiation is the method based on the thermoluminescence phenomena. Within the frame of this work, a new Panasonic's dosimetry system based on thermoluminescence dosimeters, intended for assessment of doses in mixed radiation fields of various energies is presented. In addition, the measured dosimetry quantities and problems connected with monitoring of radiation hazard in mixed fields (commonly present in medical sector) are characterized. In orderto verify measurement capabilities of the new system the irradiations of dosimeters with ionizing radiation of different energies have been done.

  7. The extended Koopmans' theorem for orbital-optimized methods: accurate computation of ionization potentials.

    PubMed

    Bozkaya, Uğur

    2013-10-21

    The extended Koopmans' theorem (EKT) provides a straightforward way to compute ionization potentials (IPs) from any level of theory, in principle. However, for non-variational methods, such as Møller-Plesset perturbation and coupled-cluster theories, the EKT computations can only be performed as by-products of analytic gradients as the relaxed generalized Fock matrix (GFM) and one- and two-particle density matrices (OPDM and TPDM, respectively) are required [J. Cioslowski, P. Piskorz, and G. Liu, J. Chem. Phys. 107, 6804 (1997)]. However, for the orbital-optimized methods both the GFM and OPDM are readily available and symmetric, as opposed to the standard post Hartree-Fock (HF) methods. Further, the orbital optimized methods solve the N-representability problem, which may arise when the relaxed particle density matrices are employed for the standard methods, by disregarding the orbital Z-vector contributions for the OPDM. Moreover, for challenging chemical systems, where spin or spatial symmetry-breaking problems are observed, the abnormal orbital response contributions arising from the numerical instabilities in the HF molecular orbital Hessian can be avoided by the orbital-optimization. Hence, it appears that the orbital-optimized methods are the most natural choice for the study of the EKT. In this research, the EKT for the orbital-optimized methods, such as orbital-optimized second- and third-order Møller-Plesset perturbation [U. Bozkaya, J. Chem. Phys. 135, 224103 (2011)] and coupled-electron pair theories [OCEPA(0)] [U. Bozkaya and C. D. Sherrill, J. Chem. Phys. 139, 054104 (2013)], are presented. The presented methods are applied to IPs of the second- and third-row atoms, and closed- and open-shell molecules. Performances of the orbital-optimized methods are compared with those of the counterpart standard methods. Especially, results of the OCEPA(0) method (with the aug-cc-pVTZ basis set) for the lowest IPs of the considered atoms and closed

  8. In vivo mutagenicity and clastogenicity of ionizing radiation in nuclear medicine. Final performance report, January 1, 1989--December 31, 1991

    SciTech Connect

    Kelsey, K.T.

    1991-12-31

    The overall goal of our research was to investigate the mutagenic and clastogenic effects of exposure to low levels of ionizing radiation to human lymphocytes. Principally, we studied hospital patients referred to a nuclear medicine department for diagnostic cardiac imaging and nuclear medicine technologists who administer radionuclides. Emphasis in the first year, as described in the first progress report, was on optimization of the hprt mutation assay, measurement of mutant frequencies in patients imaged with thallium-201, and measurement of mutant frequencies in controls. Emphasis in the second and third years was on measurements of: (1) chromosome aberrations in patients imaged with thallium-201; (2) mutant frequencies in patients imaged with technetium-99; (3) mutant frequencies in nuclear medicine technicians and physical therapists; and (4) mutant frequencies in patients treated for Hodgkins disease with radiotherapy. The completed work has been published and is described below in more detail.

  9. Nanoparticle-assisted laser desorption/ionization mass spectrometry: Novel sample preparation methods and nanoparticle screening for plant metabolite imaging

    SciTech Connect

    Yagnik, Gargey B.

    2016-02-19

    The main goal of the presented research is development of nanoparticle based matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS). This dissertation includes the application of previously developed data acquisition methods, development of novel sample preparation methods, application and comparison of novel nanoparticle matrices, and comparison of two nanoparticle matrix application methods for MALDI-MS and MALDI-MS imaging.

  10. [Electron transfer, ionization, and excitation in atomic collisions]. Final technical report, June 15, 1986--June 14, 1998

    SciTech Connect

    1998-12-31

    The research on theoretical atomic collisions that was funded at The Pennsylvania State University`s Wilkes-Barre Campus by DOE from 1986 to 1998 was carried out by Winger from 1986 to 1989 and by Winter and Alston from 1989 to 1998. The fundamental processes of electron transfer, ionization, and excitation in ion-ion, ion-atom, and, more recently, ion-molecule collisions were addressed. These collision processes were treated in the context of simple one-electron, quasi-one-electron, or two-electron systems in order to provide unambiguous results and reveal more clearly the collisional mechanisms. Winter`s work generally focused on the intermediate projectile-energy range corresponding to proton energies from about ten to a few hundred keV. In this velocity-matching energy range, the electron-transfer cross section reaches a peak, and many states, including electron-transfer and ionization states, contribute to the overall electron-cloud distribution and transition probabilities; a large number of states are coupled, and therefore perturbative approaches are generally inappropriate. These coupled-state calculations were sometimes also extended to higher energies to join with perturbative results. Alston concentrated on intermediate-energy asymmetric collision systems, for which coupling with the projectile is weaker, but many target states are included, and on high energies (MeV energies). Thus, while perturbation theory for electron transfer is valid, it is not adequate to first order. The studies by Winter and Alston described were often done in parallel. Alston also developed formal perturbative approaches not tied to any particular system. Materials studied included He{sup +}, Li{sup 2+}, Be{sup 3+}, B{sup 4+}, C{sup 5+}, and the H{sup +} + Na system.

  11. Falsely high ionized magnesium results by an ion-selective electrode method in severe hypomagnesemia.

    PubMed

    Csako, G; Rehak, N N; Elin, R J

    1997-09-01

    Changes in serum total and ionized magnesium (Mg and Mg2+) and calcium (Ca and Ca2+) were monitored in three patients who transiently developed severe (total Mg < 0.50 mmol/l) to profound hypomagnesemia (total Mg < 0.35 mmol/l) due to cisplatin or interleukin-2 therapies. Mg2+ and Ca2+ were measured with the Nova ion-selective electrodes at 37 degrees C and all results were normalized to pH 7.40. Independent of the etiology, the Mg2+ fraction (Mg2+/total Mg) increased as the concentration of the serum total Mg decreased in all three patients. When the total Mg was around or below 0.35 mmol/l the Mg2+ approached or exceeded total Mg, suggesting an error in the measurement of Mg2+. The findings were extended by including a group of 31 additional patients whose serum total Mg, Mg2+, total Ca, and Ca2+ concentrations varied from abnormally low to above normal. The serum total and ionized concentrations strongly correlated for both Mg (r2 = 0.88) and Ca (r2 = 0.92). The Mg2+ fraction rapidly increased with a fall in the total Mg concentration (r2 = 0.76) and total Mg/total Ca ratio (r2 = 0.71). In fact, with decreasing total Mg concentrations or total Mg/total Ca ratios, the Mg2+ fraction progressively increased to 93-128% of the total, confirming an error in the Mg2+ determinations. The Ca2+ fraction showed a slight and insignificant decrease with falling total Ca concentrations and total Mg/total Ca ratios. The Mg2+ concentration was directly related (r2 = 0.62), whereas the Ca2+ concentration showed a complex relationship to the total Mg/total Ca ratio. Whether this latter relationship represents a technical artifact or a true biological phenomenon requires further study. The apparent overestimation of Mg2+ at very low total Mg concentrations, and in the presence of a very low total Mg/total Ca ratio, could be due to improper chemometric correction of the Ca effect on the Mg electrode, non-linearity, and inadequate calibration. Whatever the mechanism, the failure of

  12. The Protonation Site of para-Dimethylaminobenzoic Acid Using Atmospheric Pressure Ionization Methods

    NASA Astrophysics Data System (ADS)

    Chai, Yunfeng; Weng, Guofeng; Shen, Shanshan; Sun, Cuirong; Pan, Yuanjiang

    2015-04-01

    The protonation site of para-dimethylaminobenzoic acid ( p-DMABA) was investigated using atmospheric pressure ionization methods (ESI and APCI) coupled with collision-induced dissociation (CID), nuclear magnetic resonance (NMR), and computational chemistry. Theoretical calculations and NMR experiments indicate that the dimethyl amino group is the preferred site of protonation both in the gas phase and aqueous solution. Protonation of p-DMABA occurs at the nitrogen atom by ESI independent of the solvents and other operation conditions under typical thermodynamic control. However, APCI produces a mixture of the nitrogen- and carbonyl oxygen-protonated p-DMABA when aprotic organic solvents (acetonitrile, acetone, and tetrahydrofuran) are used, exhibiting evident kinetic characteristics of protonation. But using protic organic solvents (methanol, ethanol, and isopropanol) in APCI still leads to the formation of thermodynamically stable N-protonated p-DMABA. These structural assignments were based on the different CID behavior of the N- and O-protonated p-DMABA. The losses of methyl radical and water are the diagnostic fragmentations of the N- and O-protonated p-DMABA, respectively. In addition, the N-protonated p-DMABA is more stable than the O-protonated p-DMABA in CID revealed by energy resolved experiments and theoretical calculations.

  13. A three-dimensional numerical method for modelling weakly ionized plasmas

    NASA Astrophysics Data System (ADS)

    O'Sullivan, Stephen; Downes, Turlough P.

    2007-04-01

    Astrophysical fluids under the influence of magnetic fields are often subjected to single- or two-fluid approximations. In the case of weakly ionized plasmas, however, this can be inappropriate due to distinct responses from the multiple constituent species to both collisional and non-collisional forces. As a result, in dense molecular clouds and protostellar accretion discs, for instance, the conductivity of the plasma may be highly anisotropic leading to phenomena such as Hall and ambipolar diffusion strongly influencing the dynamics. Diffusive processes are known to restrict the stability of conventional numerical schemes which are not implicit in nature. Furthermore, recent work establishes that a large Hall term can impose an additional severe stability limit on standard explicit schemes. Following a previous paper, which presented the one-dimensional case, we describe a fully three-dimensional method which relaxes the normal restrictions on explicit schemes for multifluid processes. This is achieved by applying the little-known Super TimeStepping technique to the symmetric (ambipolar) component of the evolution operator for the magnetic field in the local plasma rest frame, and the new Hall Diffusion Scheme to the skew-symmetric (Hall) component.

  14. Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules: A Benchmark of GW Methods

    NASA Astrophysics Data System (ADS)

    Marom, Noa; Knight, Joseph; Wang, Xiaopeng; Gallandi, Lukas; Dolgounitcheva, Olga; Ren, Xinguo; Ortiz, Vincent; Rinke, Patrick; Korzdorfer, Thomas

    The performance of different GW methods is assessed for a set of 24 organic acceptors. Errors are evaluated with respect to coupled cluster singles, doubles, perturbative triples [CCSD(T)] reference data for the vertical ionization potentials (IPs) and electron affinities (EAs), extrapolated to the complete basis set limit. Additional comparisons are made to experimental data, where available. We consider fully self-consistent GW (scGW), partial self-consistency in the Green's function (scGW0) , non-self-consistent G0W0 based on several mean-field starting points, and a ``beyond GW'' second order screened exchange (SOSEX) correction to G0W0. The best performers overall are G0W0 + SOSEX and G0W0 based on an IP-tuned long range corrected hybrid functional with the former being more accurate for EAs and the latter for IPs. Both provide a balanced treatment of localized vs. delocalized states and valence spectra in good agreement with photoemission spectroscopy (PES) experiments.

  15. Final Report: Symposium on Adaptive Methods for Partial Differential Equations

    SciTech Connect

    Pernice, M.; Johnson, C.R.; Smith, P.J.; Fogelson, A.

    1998-12-10

    OAK-B135 Final Report: Symposium on Adaptive Methods for Partial Differential Equations. Complex physical phenomena often include features that span a wide range of spatial and temporal scales. Accurate simulation of such phenomena can be difficult to obtain, and computations that are under-resolved can even exhibit spurious features. While it is possible to resolve small scale features by increasing the number of grid points, global grid refinement can quickly lead to problems that are intractable, even on the largest available computing facilities. These constraints are particularly severe for three dimensional problems that involve complex physics. One way to achieve the needed resolution is to refine the computational mesh locally, in only those regions where enhanced resolution is required. Adaptive solution methods concentrate computational effort in regions where it is most needed. These methods have been successfully applied to a wide variety of problems in computational science and engineering. Adaptive methods can be difficult to implement, prompting the development of tools and environments to facilitate their use. To ensure that the results of their efforts are useful, algorithm and tool developers must maintain close communication with application specialists. Conversely it remains difficult for application specialists who are unfamiliar with the methods to evaluate the trade-offs between the benefits of enhanced local resolution and the effort needed to implement an adaptive solution method.

  16. Determination of small-field correction factors for cylindrical ionization chambers using a semiempirical method

    NASA Astrophysics Data System (ADS)

    Park, Kwangwoo; Bak, Jino; Park, Sungho; Choi, Wonhoon; Park, Suk Won

    2016-02-01

    A semiempirical method based on the averaging effect of the sensitive volumes of different air-filled ionization chambers (ICs) was employed to approximate the correction factors for beam quality produced from the difference in the sizes of the reference field and small fields. We measured the output factors using several cylindrical ICs and calculated the correction factors using a mathematical method similar to deconvolution; in the method, we modeled the variable and inhomogeneous energy fluence function within the chamber cavity. The parameters of the modeled function and the correction factors were determined by solving a developed system of equations as well as on the basis of the measurement data and the geometry of the chambers. Further, Monte Carlo (MC) computations were performed using the Monaco® treatment planning system to validate the proposed method. The determined correction factors (k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} ) were comparable to the values derived from the MC computations performed using Monaco®. For example, for a 6 MV photon beam and a field size of 1  ×  1 cm2, k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} was calculated to be 1.125 for a PTW 31010 chamber and 1.022 for a PTW 31016 chamber. On the other hand, the k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} values determined from the MC computations were 1.121 and 1.031, respectively; the difference between the proposed method and the MC computation is less than 2%. In addition, we determined the k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} values for PTW 30013, PTW 31010, PTW 31016, IBA FC23-C, and IBA CC13 chambers as well. We devised a method for determining k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} from both the measurement of the output factors and model-based mathematical computation. The proposed method can be useful in case the MC simulation would not be applicable for the clinical settings.

  17. The oncogenic action of ionizing radiation on rat skin. Final progress report, May 1, 1990--April 30, 1992

    SciTech Connect

    Burns, F.J.; Garte, S.J.

    1992-12-31

    The multistage theory of carcinogenesis specifies that cells progress to cancer through a series of discrete, irreversible genetic alterations, but data on radiation-induced cancer incidence in rat skin suggests that an intermediate repairable alteration may occur. Data are presented on cancer induction in rat skin exposed to an electron beam (LET=0.34 keV/{mu}), a neon ion beam (LET=45) or an argon ion beam (LET=125). The rats were observed for tumors at least 78 weeks with squamous and basal cell carcinomas observed. The total cancer yield was fitted by the quadratic equation, and the equation parameters were estimated by linear regression for each type of radiation. Analysis of the DNA from the electron-induced carcinomas indicated that K-ras and/or c-myc oncogenes were activated. In situ hybridization indicated that the cancers contain subpopulations of cells with differing amounts of c-myc and H-ras amplification. The results are consistent with the idea that ionizing radiation produces stable, carcinogenically relevant lesions via 2 repairable events at low LET and via a non-repairable linked event pathway at high LET; either pathway may advance the cell by 1 stage. The proliferative response of rat epidermis following exposure to ionizing radiation was quantified by injection of {sup 14}C-thymidine. The return of these cells to S-phase a second time was detected by a second label ({sup 3}H). When the labeled cells were in G1-phase, the dorsal skin was irradiated with X-rays. All labeling indices were determined. The {sup 14}C labeling index was constant and unaffected by the radiation. The proportion of all cells entering S-phase averaged 3.5% at 18 hr and increased after 44, 52 and 75 hr to average levels of 11.8%, 5. 3%, and 6.6% at 0, 10 and 25 Gy respectively. The proportion of S-phase cells labeled with {sup 14}C increased after 42 hr and remained relatively constant thereafter.

  18. Flare heating and ionization of the low solar chromosphere. I - Inversion methods for Mg I 4571 and 5173

    NASA Technical Reports Server (NTRS)

    Metcalf, Thomas R.; Canfield, Richard C.; Avrett, Eugene H.; Metcalf, Frederic T.

    1990-01-01

    Various methods of inverting solar Mg I 4571 and 5173 spectral line observations are examined to find the best method of using these lines to calculate the vertical temperature and electron density structure around the temperature minimum region. Following a perturbation analysis by Mein (1971), a Fredholm integral equation of the first kind is obtained which can be inverted to yield these temperature and density structures as a function of time. Several inversion methods are tested and compared. The methods are used to test data as well as to a subset of observations of these absorption lines taken on February 3, 1986 before and during a solar flare. A small but significant increase is found in the temperature and a relatively large increase in the electron density during this flare. The observations are inconsistent with heating and ionization by an intense beam of electrons and with ionization by UV photoionization of Si I.

  19. Flare heating and ionization of the low solar chromosphere. I - Inversion methods for Mg I 4571 and 5173

    NASA Technical Reports Server (NTRS)

    Metcalf, Thomas R.; Canfield, Richard C.; Avrett, Eugene H.; Metcalf, Frederic T.

    1990-01-01

    Various methods of inverting solar Mg I 4571 and 5173 spectral line observations are examined to find the best method of using these lines to calculate the vertical temperature and electron density structure around the temperature minimum region. Following a perturbation analysis by Mein (1971), a Fredholm integral equation of the first kind is obtained which can be inverted to yield these temperature and density structures as a function of time. Several inversion methods are tested and compared. The methods are used to test data as well as to a subset of observations of these absorption lines taken on February 3, 1986 before and during a solar flare. A small but significant increase is found in the temperature and a relatively large increase in the electron density during this flare. The observations are inconsistent with heating and ionization by an intense beam of electrons and with ionization by UV photoionization of Si I.

  20. Ionization suppression effects with condensed phase membrane introduction mass spectrometry: methods to increase the linear dynamic range and sensitivity.

    PubMed

    Duncan, Kyle D; Vandergrift, Gregory W; Krogh, Erik T; Gill, Chris G

    2015-03-01

    Condensed phase membrane introduction mass spectrometry (CP-MIMS) is an online analytical method that allows for the direct, trace level measurement of a wide range of analytes in complex samples. The technique employs a semi-permeable membrane that transfers analytes from a sample into a flowing acceptor solvent, which is directly infused to an atmospheric pressure ionization source, such as electrospray or atmospheric pressure chemical ionization. While CP-MIMS and variants of the technique have been in the literature for nearly a decade, much of the work has focused on instrument development. Few studies have thoroughly addressed quantitative methods related to detection limits, ionization suppression, or linear dynamic range. We examine ionization suppression in the direct rapid quantitation of analytes by CP-MIMS and introduce several analytical strategies to mitigate these effects, including the novel implementation of a continuously infused internal standard in the acceptor phase solvent, and modulation of acceptor phase flow rate. Several representative analytes were used to evaluate this approach with spiked, complex sample matrices, including primary wastewater effluent and artificial urine. Also reported are improved measured detection limits in the low part-per-trillion range, using a 'stopped-flow' acceptor mode.

  1. Methods for Creation and Detection of Ultra-Strong Artificial Ionization in the Upper Atmosphere (Invited)

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Siefring, C. L.; Briczinski, S. J.; Kendall, E. A.; Watkins, B. J.; Bristow, W. A.; Michell, R.

    2013-12-01

    The High Frequency Active Auroral Research Program (HAARP) transmitter in Alaska has been used to produce localized regions of artificial ionization at altitudes between 150 and 250 km. High power radio waves tuned near harmonics of the electron gyro frequency were discovered by Todd Pederson of the Air Force Research Laboratory to produce ionosonde traces that looked like artificial ionization layers below the natural F-region. The initial regions of artificial ionization (AI) were not stable but had moved down in altitude over a period of 15 minutes. Recently, artificial ionization has been produced by the 2nd, 3rd, 4th and 6th harmonics transmissions by the HAARP. In march 2013, the artificial ionization clouds were sustained for more the 5 hours using HAARP tuned to the 4 fce at the full power of 3.6 Mega-Watts with a twisted-beam antenna pattern. Frequency selection with narrow-band sweeps and antenna pattern shaping has been employed for optimal generation of AI. Recent research at HAARP has produced the longest lived and denser artificial ionization clouds using HF transmissions at the harmonics of the electron cyclotron frequency and ring-shaped radio beams tailored to prevent the descent of the clouds. Detection of artificial ionization employs (1) ionosonde echoes, (2) coherent backscatter from the Kodiak SuperDARN radar, (3) enhanced ion and plasma line echoes from the HAARP MUIR radar at 400 MHz, (4) high resolution optical image from ground sites, and (5) unique stimulated electromagnetic emissions, and (6) strong UHF and L-Band scintillation induced into trans-ionospheric signals from satellite radio beacons. Future HAARP experiments will determine the uses of long-sustained AI for enhanced HF communications.

  2. Pseudostate methods and differential cross sections for antiproton ionization of atomic hydrogen and helium

    SciTech Connect

    McGovern, M.; Walters, H. R. J.; Assafrao, D.; Mohallem, J. R.; Whelan, Colm T.

    2010-03-15

    A relaxed form of a recent impact parameter coupled pseudostate approximation of McGovern et al. [Phys. Rev. A 79, 042707 (2009)] for calculating differential ionization cross sections is proposed. This greatly eases the computational burden in cases where a range of ejected electron energies has to be considered. The relaxed approximation is tested against exact first Born calculations for antiproton impact on H and nonperturbatively for the highly nonperturbative system of Au{sup 53+} incident upon He. The approximation performs well in these tests. It is shown how, with a little further approximation, the relaxed theory leads to a widely used prescription for the total ionization cross section. Results for differential ionization of H and He by antiprotons are presented. These reveal the growing dominance of the interaction between the antiproton and the target nucleus at low impact energies and show the changing importance of the role of the postcollisional interaction between the antiproton and the ejected electron.

  3. Correction factors for the INER-improved free-air ionization chambers calculated with the Monte Carlo method.

    PubMed

    Lin, Uei-Tyng; Chu, Chien-Hau

    2006-05-01

    Monte Carlo method was used to simulate the correction factors for electron loss and scattered photons for two improved cylindrical free-air ionization chambers (FACs) constructed at the Institute of Nuclear Energy Research (INER, Taiwan). The method is based on weighting correction factors for mono-energetic photons with X-ray spectra. The newly obtained correction factors for the medium-energy free-air chamber were compared with the current values, which were based on a least-squares fit to experimental data published in the NBS Handbook 64 [Wyckoff, H.O., Attix, F.H., 1969. Design of free-air ionization chambers. National Bureau Standards Handbook, No. 64. US Government Printing Office, Washington, DC, pp. 1-16; Chen, W.L., Su, S.H., Su, L.L., Hwang, W.S., 1999. Improved free-air ionization chamber for the measurement of X-rays. Metrologia 36, 19-24]. The comparison results showed the agreement between the Monte Carlo method and experimental data is within 0.22%. In addition, mono-energetic correction factors for the low-energy free-air chamber were calculated. Average correction factors were then derived for measured and theoretical X-ray spectra at 30-50 kVp. Although the measured and calculated spectra differ slightly, the resulting differences in the derived correction factors are less than 0.02%.

  4. A method for measuring the electron drift velocity in working gas using a Frisch-grid ionization chamber

    NASA Astrophysics Data System (ADS)

    Bai, Huaiyong; Wang, Zhimin; Zhang, Luyu; Chen, Jinxiang; Zhang, Guohui

    2016-12-01

    A method for measuring the electron drift velocity in working gas is proposed. Based on the cathode and the anode signal waveforms of the Frisch-grid ionization chamber, the electron drift velocity is extracted. With this method, the electron drift velocities in Ar + 10% CH4, Ar + 3.5% CO2 and Kr + 2.7% CO2 gases have been measured and the results are compared with the existing measurements and the simulating results. Using this method, the electron drift velocity can be monitored throughout the experiment of charged particle without bothering the measurement of other parameters, such as the energy and orientation.

  5. Slow-electron velocity-map imaging study of aniline via resonance-enhanced two-photon ionization method

    NASA Astrophysics Data System (ADS)

    Qu, Zehua; Qin, Zhengbo; Zheng, Xianfeng; Wang, Hui; Yao, Guanxin; Zhang, Xianyi; Cui, Zhifeng

    2017-02-01

    Slow electron velocity-map imaging (SEVI) of aniline has been investigated via two-color resonant-enhanced two-photo (1 + 1‧) ionization (2C-R2PI) method. A number of vibrational frequencies in the first excited state of neutral (S1) and 2B1 ground electronic state of cation (D0) have been accurately determined. In addition, photoelectron angular distributions (PADs) in the two-step transitions are presented and reveal a near threshold shape resonance in the ionization of aniline. The SEVI spectra taken via various S1 intermediate states provide the detailed vibrational structures of D0 state and directly deduce the accurate adiabatic ionization potential (IP) of 62,271 ± 6 cm- 1. Ab initio calculations excellently reproduce the experimental IP value (Theo. 62,242 cm- 1). For most vibrational modes, good agreement between theoretical and experimental frequencies in the S0 and D0 states of aniline is obtained to aid us to clearly assign vibrational modes. Especially, the vibrational frequencies calculated at the CASSCF level are much better consistent with experimental data than that obtained using the TDDFT and CIS methods.

  6. Slow-electron velocity-map imaging study of aniline via resonance-enhanced two-photon ionization method.

    PubMed

    Qu, Zehua; Qin, Zhengbo; Zheng, Xianfeng; Wang, Hui; Yao, Guanxin; Zhang, Xianyi; Cui, Zhifeng

    2017-02-15

    Slow electron velocity-map imaging (SEVI) of aniline has been investigated via two-color resonant-enhanced two-photo (1+1') ionization (2C-R2PI) method. A number of vibrational frequencies in the first excited state of neutral (S1) and (2)B1 ground electronic state of cation (D0) have been accurately determined. In addition, photoelectron angular distributions (PADs) in the two-step transitions are presented and reveal a near threshold shape resonance in the ionization of aniline. The SEVI spectra taken via various S1 intermediate states provide the detailed vibrational structures of D0 state and directly deduce the accurate adiabatic ionization potential (IP) of 62,271±6cm(-1). Ab initio calculations excellently reproduce the experimental IP value (Theo. 62,242cm(-1)). For most vibrational modes, good agreement between theoretical and experimental frequencies in the S0 and D0 states of aniline is obtained to aid us to clearly assign vibrational modes. Especially, the vibrational frequencies calculated at the CASSCF level are much better consistent with experimental data than that obtained using the TDDFT and CIS methods.

  7. Expedient methods of respiratory protection. II. Leakage tests. Final report

    SciTech Connect

    Cooper, D.W.; Hinds, W.C.; Price, J.M.; Weker, R.; Yee, H.S.

    1983-07-01

    The following readily-available materials were tested on a manikin connected to a breathing simulator to determine the fraction of an approximately 2-..mu..m-diameter aerosol that would leak around the seal of the materials to the manikin's face: cotton/polyester shirt material, cotton handkerchief material, toweling (a wash cloth), a surgical mask (Johnson and Johnson Co., model HRI 8137), and a NIOSH-approved disposable face mask (3M, model number 8710). The leakage tests were performed to supplement the measurements of penetration through the materials, conducted as the first phase of this investigation. The leakage tests were performed with the materials held on to the face by three methods, leakage fractions being determined from comparisons with the penetration of the same aerosol for the materials fully taped to the face. At a breathing rate of 37 liters per minute, mean leakages ranged from 0.0 percent to 63 percent. Mean penetrations exclusive of leakage ranged from 0.6 percent to 39 percent. Use of nylon hosiery material (panty hose) to hold the handkerchief material or the disposable face mask to the face was found to be very effective in preventing leakage. Such a combination could be expected to reduce leakage around the handkerchief to about ten percent or less in practice, and around the mask to less than one percent, offering substantial protection from accidentally generated aerosols. The reduction in leakage around the mask provided by the hosiery material suggests the adaptation and use of such an approach in regular industrial hygiene practice. The third and final phase of this investigation is underway, in which the penetration of the materials by particles with diameters between 0.05 and 0.5 ..mu..m is being measured and the effectiveness of the methods for dose reduction in the presence of radioactive aerosols is being modeled.

  8. The calculation of ionization energies by perturbation, configuration interaction and approximate coupled pair techniques and comparisons with green's function methods for Ne, H 2O and N 2

    NASA Astrophysics Data System (ADS)

    Bacskay, George B.

    1980-05-01

    The vertical valence ionization potentials of Ne, H 2O and N 2 have been calculated by Rayleigh-Schrödinger perturbation and configuration interaction methods. The calculations were carried out in the space of a single determinant reference state and its single and double excitations, using both the N and N - 1 electron Hartree-Fock orbitals as hole/particle bases. The perturbation series for the ion state were generally found to converge fairly slowly in the N electron Hartree-Fock (frozen) orbital basis, but considerably faster in the appropriate N - 1 electron RHF (relaxed) orbital basis. In certain cases, however, due to near-degeneracy effects, partial, and even complete, breakdown of the (non-degenerate) perturbation treatment was observed. The effects of higher excitations on the ionization potentials were estimated by the approximate coupled pair techniques CPA' and CPA″ as well as by a Davidson type correction formula. The final, fully converged CPA″ results are generally in good agreement with those from PNO-CEPA and Green's function calculations as well as experiment.

  9. Time-independent and time-dependent close-coupling methods for the electron-impact ionization of ?, ? and ?

    NASA Astrophysics Data System (ADS)

    Badnell, N. R.; Pindzola, M. S.; Bray, I.; Griffin, D. C.

    1998-02-01

    The electron-impact ionization cross sections of 0953-4075/31/4/032/img10, 0953-4075/31/4/032/img11 and 0953-4075/31/4/032/img12 are calculated using both time-independent and time-dependent close-coupling methods. The time-independent methods are R-matrix and convergent close-coupling solutions based on a total wavefunction constructed using antisymmetrized products of Laguerre pseudo-orbitals and physical bound orbitals. The time-dependent method is based on the propagation of wavepackets constructed using excited-state orbitals calculated in a core pseudo-potential. The results of all three methods are in good agreement for 0953-4075/31/4/032/img10; there is also good agreement between the R-matrix and time-dependent methods for 0953-4075/31/4/032/img11 and 0953-4075/31/4/032/img12, and all three methods yield ionization cross sections that lie substantially above the experimental crossed-beams measurements of Crandall et al. There is better accord with the crossed-beams measurements of Peart et al for 0953-4075/31/4/032/img10, but the theoretical results still lie 10% higher at 50 eV. Some disagreement is noted, for both 0953-4075/31/4/032/img11 and 0953-4075/31/4/032/img12, between the convergent close-coupling results and the R-matrix and time-dependent results.

  10. Numerical conformal mapping: Methods, applications, and theory. Final report

    SciTech Connect

    DeLillo, T.K.

    1995-11-01

    Section 1 of this report, briefly summarizes research performed under this grant during the first two years 1992 to 1994 and makes some overall remarks. Section 2, summarizes research performed during the final year from September, 1994 through May 31, 1995, more fully. The main achievement of the last period has been the application of numerical conformed mapping to the solution of the biharmonic equation. Section 3, summarizes travel, meetings, and other expenses supported by this grant during the final year.

  11. Fuel cell with ionization membrane

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T. (Inventor)

    2007-01-01

    A fuel cell is disclosed comprising an ionization membrane having at least one area through which gas is passed, and which ionizes the gas passing therethrough, and a cathode for receiving the ions generated by the ionization membrane. The ionization membrane may include one or more openings in the membrane with electrodes that are located closer than a mean free path of molecules within the gas to be ionized. Methods of manufacture are also provided.

  12. METHOD 332.0: DETERMINATION OF PERCHLORATE IN DRINKING WATER BY ION CHROMATOGRAPHY WITH SUPPRESSED CONDUCTIVITY AND ELECTROSPRAY IONIZATION MASS SPECTROMETRY

    EPA Science Inventory

    This method is applicable to the identification and quantitation of perchlorate in raw and finished drinking waters. The approach used is ion chromatography with suppressed conductivity and electrospray ionization mass spectrometry (IC-ESI/MS)

  13. METHOD 332.0: DETERMINATION OF PERCHLORATE IN DRINKING WATER BY ION CHROMATOGRAPHY WITH SUPPRESSED CONDUCTIVITY AND ELECTROSPRAY IONIZATION MASS SPECTROMETRY

    EPA Science Inventory

    This method is applicable to the identification and quantitation of perchlorate in raw and finished drinking waters. The approach used is ion chromatography with suppressed conductivity and electrospray ionization mass spectrometry (IC-ESI/MS)

  14. Ionization source utilizing a jet disturber in combination with an ion funnel and method of operation

    DOEpatents

    Smith, Richard D.; Kim, Taeman; Tang, Keqi; Udseth, Harold R.

    2003-06-24

    A jet disturber used in combination with an ion funnel to focus ions and other charged particles generated at or near atmospheric pressure into a relatively low pressure region, which allows increased conductance of the ions and other charged particles. The jet disturber is positioned within an ion funnel and may be interfaced with a multi-capillary inlet juxtaposed between an ion source and the interior of an instrument maintained at near atmospheric pressure. The invention finds particular advantages when deployed to improve the ion transmission between an electrospray ionization source and the first vacuum stage of a mass spectrometer.

  15. Method for analyzing the mass of a sample using a cold cathode ionization source mass filter

    DOEpatents

    Felter, Thomas E.

    2003-10-14

    An improved quadrupole mass spectrometer is described. The improvement lies in the substitution of the conventional hot filament electron source with a cold cathode field emitter array which in turn allows operating a small QMS at much high internal pressures then are currently achievable. By eliminating of the hot filament such problems as thermally "cracking" delicate analyte molecules, outgassing a "hot" filament, high power requirements, filament contamination by outgas species, and spurious em fields are avoid all together. In addition, the ability of produce FEAs using well-known and well developed photolithographic techniques, permits building a QMS having multiple redundancies of the ionization source at very low additional cost.

  16. Calculations of the ionization potentials of the halogens by the relativistic Hartree-Rock-Dirac method taking account of superposition of configurations

    SciTech Connect

    Tupitsyn, I.I.

    1988-03-01

    The ionization potentials of the halogen group have been calculated. The calculations were carried out using the relativistic Hartree-Fock method taking into account correlation effects. Comparison of theoretical results with experimental data for the elements F, Cl, Br, and I allows an estimation of the accuracy and reliability of the method. The theoretical values of the ionization potential of astatine obtained here may be of definite interest for the chemistry of astatine.

  17. Air flow-assisted ionization imaging mass spectrometry method for easy whole-body molecular imaging under ambient conditions.

    PubMed

    Luo, Zhigang; He, Jiuming; Chen, Yi; He, Jingjing; Gong, Tao; Tang, Fei; Wang, Xiaohao; Zhang, Ruiping; Huang, Lan; Zhang, Lianfeng; Lv, Haining; Ma, Shuanggang; Fu, Zhaodi; Chen, Xiaoguang; Yu, Shishan; Abliz, Zeper

    2013-03-05

    Whole-body molecular imaging is able to directly map spatial distribution of molecules and monitor its biotransformation in intact biological tissue sections. Imaging mass spectrometry (IMS), a label-free molecular imaging method, can be used to image multiple molecules in a single measurement with high specificity. Herein, a novel easy-to-implement, whole-body IMS method was developed with air flow-assisted ionization in a desorption electrospray ionization mode. The developed IMS method can effectively image molecules in a large whole-body section in open air without sample pretreatment, such as chemical labeling, section division, or matrix deposition. Moreover, the signal levels were improved, and the spatial assignment errors were eliminated; thus, high-quality whole-body images were obtained. With this novel IMS method, in situ mapping analysis of molecules was performed in adult rat sections with picomolar sensitivity under ambient conditions, and the dynamic information of molecule distribution and its biotransformation was provided to uncover molecular events at the whole-animal level. A global view of the differential distribution of an anticancer agent and its metabolites was simultaneously acquired in whole-body rat and model mouse bearing neuroglioma along the administration time. The obtained drug distribution provided rich information for identifying the targeted organs and predicting possible tumor spectrum, pharmacological activity, and potential toxicity of drug candidates.

  18. A practical gas chromatography flame ionization detection method for the determination of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane in silicone emulsions.

    PubMed

    Brothers, Herbert M; Bovens, Eric; Bruni, Antonio; Habitz, Tanya M; Hamachi, Tadashi; Han, Yuanhua; Ji, Zhouhua; Kerbleski, Joel J; Letouche, Claude; Lu, Yi Dong; Nguyen, Regis; Rivard, Michelle L; Qi, Xiaoman; Shoji, Miki; Tanaka, Ken; Tecklenburg, Ronald E

    2016-04-08

    A gas chromatography with flame ionization detection (GC-FID) method for analysis of D4, D5, and D6 cyclic siloxanes in silicone emulsions is described. Sample preparation involves breaking the emulsion with methanol and hexanes, and then analyzing the hexanes phase after derivatization with hexamethyldisilazane (HMDS). Silylation is performed to reduce the potential for formation of cyclic siloxanes during the course of the GC analysis. The accuracy of the method was verified by performing analyses on samples spiked with known levels of D4, D5 and D6 and by comparison to a referee method using atmospheric pressure chemical ionization liquid chromatography with mass spectrometry detection (APCI-LC-MS). Absolute differences of the results obtained between the two techniques were 0.03 weight percent or less, and relative differences were 15% or less. The reproducibility and ruggedness of the method was demonstrated by performing a global round robin test at four different geographic sites on four different types of silicone emulsions. The %RSDs obtained were less than 10% for all analytes and all emulsions examined. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Atmospheric pressure photo ionization hydrogen/deuterium exchange mass spectrometry--a method to differentiate isomers by mass spectrometry.

    PubMed

    Ahmed, Arif; Kim, Sunghwan

    2013-12-01

    In this report, a method for in-source hydrogen/deuterium (H/D) exchange at atmospheric pressure is reported. The method was named atmospheric pressure photo ionization hydrogen/deuterium exchange mass spectrometry (APPI HDX MS). H/D exchange was performed by mixing samples dissolved in toluene with CH3OD solvent and analyzing the mixture using atmospheric pressure photo ionization mass spectrometry (APPI-MS). The APPI HDX spectra obtained with contact times between the analyte solution and methanol-OD (CH3OD) of < 0.5 s or 1 h showed the same pattern of H/D exchange. Therefore, it was concluded that APPI HDX occurred in the source but not in the solution. The proposed method does not require a specific type of mass spectrometer and can be performed at atmospheric pressure. H/D exchange can be performed in any laboratory with a mass spectrometer and a commercial APPI source. Using this method, multiple H/D exchanges of aromatic hydrogen and/or H/D exchange of active hydrogen were observed. These results demonstrated that H/D exchange can be used to distinguish between isomers containing primary, secondary, and tertiary amines, as well as pyridine and pyrrole functional groups.

  20. Method for Calculation of Ionization Profiles Caused by Cosmic Rays in Giant Planet Ionospheres from Jovian Group

    NASA Astrophysics Data System (ADS)

    Velinov, P.; Kostov, V.; Ruder, H.; Mateev, L.; Buchvarova, M.

    As a continuation of our studies of cosmic ray (CR) ionization in the atmospheres and ionospheres of the planets in the Solar system we present a new method for the calculation of the full electron production rate profiles due to particles of all energy intervals (galactic and solar CR, anomalous CR component and other types of high energy particles). For giant planets which have significant oblateness in spite of the isotropic penetration of the galactic CR in their atmospheres, the trivial integration on the azimuth angle is not applicable, because of the presentation of the planets as rotational ellipsoids and the azimuth dependence of the integrand function. The differences in the electron production rates for spherical and oblate atmospheres of the terrestrial planets are small. For example, for Mars and Earth this difference does not exceed 5% and almost does not depend on altitude. For the giant planets, however, there is a considerable dependency on height in the atmosphere. The differences in the electron p oduction rate profiles for spherical and ellipsoidalr atmospheres increase significantly in the deeper atmospheric layers. This requires the introduction of a modified Chapman ( h ) function for oblate planet in theC Particle Depth Factor (PDF) while considering the CR influence and ionization- neutralization processes in the ionospheres of the giant planets: Jupiter, Saturn, Uranus and Neptune. Calculation of ionization by all particles from different directions requires integration over azimuth angle, instead of only over zenith angle as in the spherical planet case when the Ch function is used. For an oblate planetary body (rotational ellipsoid), the atmospheric parameters (density and optical depth) depend on particle trajectory azimuth angle, so even for CR with isotropic distributions, integration over azimuth angle, zenith angle and energy is necessary. The goal of the present paper is the application of the PDF function for rotational ellipsoid

  1. Three-dimensional Finite Elements Method simulation of Total Ionizing Dose in 22 nm bulk nFinFETs

    NASA Astrophysics Data System (ADS)

    Chatzikyriakou, Eleni; Potter, Kenneth; Redman-White, William; De Groot, C. H.

    2017-02-01

    Finite Elements Method simulation of Total Ionizing Dose effects on 22 nm bulk Fin Field Effect Transistor (FinFET) devices using the commercial software Synopsys Sentaurus TCAD is presented. The simulation parameters are extracted by calibrating the charge trapping model to experimental results on 400 nm SiO2 capacitors irradiated under zero bias. The FinFET device characteristics are calibrated to the Intel 22 nm bulk technology. Irradiation simulations of the transistor performed with all terminals unbiased reveal increased hardness up to a total dose of 1 MRad(SiO2).

  2. Absolute method for the assay of oleuropein in olive oils by atmospheric pressure chemical ionization tandem mass spectrometry.

    PubMed

    De Nino, Antonio; Di Donna, Leonardo; Mazzotti, Fabio; Muzzalupo, Enzo; Perri, Enzo; Sindona, Giovanni; Tagarelli, Antonio

    2005-09-15

    Oleuropein (OLP, 1), the active ingredient present (i) in food integrators extracted from olive leaves, (ii) in table olives, and (iii) in extra virgin olive oils is a nutraceutical whose health benefits have been widely documented. A new analytical method for its assay, which is based on the utilization of atmospheric pressure chemical ionization tandem mass spectrometry and on the use of a synthetic labeled analogue, the 4-trideuteriocarboxyoleuropein (2), as an internal standard, is presented. The results obtained with extra virgin olive oils from different cultivars and different Italian regions are discussed.

  3. Equation of motion coupled cluster methods for electron attachment and ionization potential in fullerenes C60 and C70

    SciTech Connect

    Bhaskaran-Nair, Kiran; Kowalski, Karol; Moreno, Juana; Jarrell, Mark; Shelton, William A.

    2014-08-21

    Discovery of fullerenes has opened a entirely new chapter in chemistry due to their wide range of properties which holds exciting applications in numerous disciplines of science. The Nobel Prize in Chemistry 1996 was awarded jointly to Robert F. Curl Jr., Sir Harold W. Kroto and Richard E. Smalley in recoginition for their discovery of this new carbon allotrope. In this letter we are reporting ionization potential and electron attachment studies on fullerenes (C60 and C70) obtained with novel parallel implementation of the EA-EOM-CCSD and IP-EOM-CCSD methods in NWChem program package.

  4. System and method of infrared matrix-assisted laser desorption/ionization mass spectrometry in polyacrylamide gels

    DOEpatents

    Haglund, Jr., Richard F.; Ermer, David R.; Baltz-Knorr, Michelle Lee

    2004-11-30

    A system and method for desorption and ionization of analytes in an ablation medium. In one embodiment, the method includes the steps of preparing a sample having analytes in a medium including at least one component, freezing the sample at a sufficiently low temperature so that at least part of the sample has a phase transition, and irradiating the frozen sample with short-pulse radiation to cause medium ablation and desorption and ionization of the analytes. The method further includes the steps of selecting a resonant vibrational mode of at least one component of the medium and selecting an energy source tuned to emit radiation substantially at the wavelength of the selected resonant vibrational mode. The medium is an electrophoresis medium having polyacrylamide. In one embodiment, the energy source is a laser, where the laser can be a free electron laser tunable to generate short-pulse radiation. Alternatively, the laser can be a solid state laser tunable to generate short-pulse radiation. The laser can emit light at various ranges of wavelength.

  5. Development and Validation of a Multiclass Method for Analysis of Veterinary Drug Residues in Milk Using Ultrahigh Performance Liquid Chromatography Electrospray Ionization Quadrupole Orbitrap Mass Spectrometry.

    PubMed

    Wang, Jian; Leung, Daniel; Chow, Willis; Chang, James; Wong, Jon W

    2015-10-21

    This paper presents the development and validation of a multiclass method for the analysis of veterinary drug residues in milk using ultrahigh performance liquid chromatography electrospray ionization quadrupole Orbitrap mass spectrometry (UHPLC/ESI Q-Orbitrap). The 12 classes of veterinary drugs (a total of 125) included in this study were endectocides, fluoroquinolones, ionophores, macrolides, nitroimidazole, NSAIDs, β-lactams, penicillins, phenicols, sulfonamides, tetracyclines, and aminoglycosides. Veterinary drug residues in milk were extracted using a modified salting-out supported liquid extraction (SOSLE) method, which entailed the precipitation of milk proteins using an extraction buffer (oxalic acid and EDTA, pH 3) and acetonitrile, a salting-out acetonitrile/water phase separation using ammonium sulfate, and solid-phase extraction (SPE) using polymeric reversed-phase sorbent cartridges. The final extracts were concentrated and reconstituted into a buffer solution and analyzed using UHPLC/ESI Q-Orbitrap mass spectrometry. The developed method was validated using a nested experimental design to evaluate the method performance characteristics, such as overall recovery, intermediate precision, and measurement uncertainty. The method was able to quantify or screen up to 105 veterinary drugs from 11 different classes, except aminoglycosides. The limits of quantification were as low as 1.0 μg/kg, with an analytical range from 1.0 to 100.0 μg/kg in milk.

  6. Grid-based methods for diatomic quantum scattering problems II: Time-dependent treatment of single- and two-photon ionization of H2+

    SciTech Connect

    Rescigno, Thomas N.; Tao, L.; McCurdy, C.W.

    2009-04-20

    The time-dependent Schr\\"odinger equation for H2+ in a time-varying electromagnetic field is solved in the fixed-nuclei approximation using a previously developed finite-element/ discrete variable representation in prolate spheroidal coordinates. Amplitudes for single- and two-photon ionization are obtained using the method of exterior complex scaling to effectively propagate the field-free solutions from the end of the radiation pulse to infinite times. Cross sections are presented for one-and two-photon ionization for both parallel and perpendicular polarization of the photon field, as well as photoelectron angular distributions for two-photon ionization.

  7. New methods and instrumentation for the characterization of biopolymers using electrospray ionization-mass spectrometry

    SciTech Connect

    Smith, R.D.; Udseth, H.R.; Rockwood, A.L.; Winger, B.E.; Hofstadler, S.A.; Goodlett, D.R.; Light-Wahl, K.J.

    1992-09-01

    The technique of electrospray ionization (ESI) has significantly extended the ability to characterize large molecules by mass spectrometry. Proteins to at least 200,000 D can be transferred intact to the gas phase and molecular weights determined with precisions as high as 0.001% if individual charge states can be resolved. The ESI-MS can also serve as a near ideal interface and detector for capillary column separations providing a basis for highly efficient sample utilization. Using capillary electrophoresis (CE)-MS, injection quantities in the 10[sup [minus]18] mole range can be detected for smaller polypeptides using selected ion monitoring, and separation efficiencies as high as 5[center dot]10[sup 5] theoretical plates have been realized. We have recently shown that the use of small 5 [mu]m i.d. capillaries allows CE-MS with scanning detection for proteins for injection of 600 attomoles.

  8. New methods and instrumentation for the characterization of biopolymers using electrospray ionization-mass spectrometry

    SciTech Connect

    Smith, R.D.; Udseth, H.R.; Rockwood, A.L.; Winger, B.E.; Hofstadler, S.A.; Goodlett, D.R.; Light-Wahl, K.J.

    1992-09-01

    The technique of electrospray ionization (ESI) has significantly extended the ability to characterize large molecules by mass spectrometry. Proteins to at least 200,000 D can be transferred intact to the gas phase and molecular weights determined with precisions as high as 0.001% if individual charge states can be resolved. The ESI-MS can also serve as a near ideal interface and detector for capillary column separations providing a basis for highly efficient sample utilization. Using capillary electrophoresis (CE)-MS, injection quantities in the 10{sup {minus}18} mole range can be detected for smaller polypeptides using selected ion monitoring, and separation efficiencies as high as 5{center_dot}10{sup 5} theoretical plates have been realized. We have recently shown that the use of small 5 {mu}m i.d. capillaries allows CE-MS with scanning detection for proteins for injection of 600 attomoles.

  9. Creating a strategy for science-based national policy: Addressing conflicting views on the health risk of low-level ionizing radiation. Final report, Wingspread Conference

    SciTech Connect

    McClellan, Roger O.; Apple, Martin A.

    1998-03-03

    Significant cancer risk for adults exposed to more than 100 millisieverts (10 REM) of ionizing radiation. More research on low-level ionizing radiation is needed in molecular and cellular mechanisms of injury and ongoing exposed populations. Implementation costs should be considered in regulating low-level ionizing radiation. Comparative risk assessment is a powerful tool for risk-based policy formation, and conflicting legal statutes should become harmonized for radiation regulation. More public dialog on low-level radiation is needed. A high level commission should evaluate radiation hazard control practices.

  10. Final report on the Copper Mountain conference on multigrid methods

    SciTech Connect

    1997-10-01

    The Copper Mountain Conference on Multigrid Methods was held on April 6-11, 1997. It took the same format used in the previous Copper Mountain Conferences on Multigrid Method conferences. Over 87 mathematicians from all over the world attended the meeting. 56 half-hour talks on current research topics were presented. Talks with similar content were organized into sessions. Session topics included: fluids; domain decomposition; iterative methods; basics; adaptive methods; non-linear filtering; CFD; applications; transport; algebraic solvers; supercomputing; and student paper winners.

  11. Comparison of Two Methods for the Determination of the Effects of Ionizing Radiation on Blood Cell Counts in Mice

    PubMed Central

    Romero-Weaver, Ana L.; Kennedy, Ann R.

    2012-01-01

    A reliable technique is needed to determine the effect of ionizing radiation on white blood cell (WBC) counts. Facilities that utilize automated methods can provide this service. However, utilizing external facilities can introduce additional variables, such as differences between time of sample collection and time of sample processing, which may affect the results. The purpose of the present study was to determine whether an automated method at an external facility can accurately determine radiation-induced changes in total WBC, lymphocyte and granulocyte counts when samples are analyzed at periods of time up to 24 hours after collection and stored either at room temperature or at 4°C. To accomplish this, we compared automated blood cell counts determined at an external facility with our manual blood cell counts processed immediately after sample collection or 24 h after sample collection and stored either at room temperature or 4°C from mice exposed to 2 Gy proton or 2 Gy gamma radiation. Our results show a close correlation and good agreement between the two methods, indicating that neither a delay of 24 hours in sample processing nor storage temperature affected white blood cell counts. Analysis of the effects of radiation on blood cell counts by either manual or automated cell counts revealed a statistically significant decrease in lymphocyte and granulocyte counts at different days post-irradiation, with no statistically significant difference between the methods employed; therefore both manual and automated blood cell counts are reliable methods to determine the effects of ionizing radiation in blood cells. PMID:23450807

  12. Interdisciplinary Curriculum Development in Hospital Methods Improvement. Final Report.

    ERIC Educational Resources Information Center

    Watt, John R.

    The major purpose of this project was to develop a "package" curriculum of Hospital Methods Improvement techniques for college students in health related majors. The elementary Industrial Engineering methods for simplifying work and saving labor were applied to the hospital environment and its complex of problems. The report's…

  13. Sixth Copper Mountain Conference on Multigrid Methods. Final report

    SciTech Connect

    Not Available

    1994-07-01

    During the 5-day meeting, 112 half-hour talks on current research topics were presented. Session topics included: fluids, domain decomposition, iterative methods, Basics I and II, adaptive methods, nonlinear filtering, CFD I, II, and III, applications, transport, algebraic solvers, supercomputing, and student paper winners.

  14. Efficient Methods to Generate Reproducible Mass Spectra in Matrix-Assisted Laser Desorption Ionization of Peptides

    NASA Astrophysics Data System (ADS)

    Ahn, Sung Hee; Park, Kyung Man; Bae, Yong Jin; Kim, Myung Soo

    2013-06-01

    In our previous matrix-assisted laser desorption ionization (MALDI) studies of peptides, we found that their mass spectra were virtually determined by the effective temperature in the early matrix plume, Tearly, when samples were rather homogeneous. This empirical rule allowed acquisition of quantitatively reproducible spectra. A difficulty in utilizing this rule was the complicated spectral treatment needed to get Tearly. In this work, we found another empirical rule that the total number of particles hitting the detector, or TIC, was a good measure of the spectral temperature and, hence, selection of spectra with the same TIC resulted in reproducible spectra. We also succeeded in obtaining reproducible spectra throughout a measurement by controlling TIC near a preset value through feedback adjustment of laser pulse energy. Both TIC selection and TIC control substantially reduced the shot-to-shot spectral variation in a spot, spot-to-spot variation in a sample, and even sample-to-sample variation in MALDI using α-cyano-4-hydroxycinnamic acid or 2,5-dihydroxybenzoic acid as matrix. Based on the utilization of acquired data, TIC control was more efficient than TIC selection by an order of magnitude. Both techniques produced calibration curves with excellent linearity, suggesting their utility in quantification of peptides.

  15. Efficient methods to generate reproducible mass spectra in matrix-assisted laser desorption ionization of peptides.

    PubMed

    Ahn, Sung Hee; Park, Kyung Man; Bae, Yong Jin; Kim, Myung Soo

    2013-06-01

    In our previous matrix-assisted laser desorption ionization (MALDI) studies of peptides, we found that their mass spectra were virtually determined by the effective temperature in the early matrix plume, Tearly, when samples were rather homogeneous. This empirical rule allowed acquisition of quantitatively reproducible spectra. A difficulty in utilizing this rule was the complicated spectral treatment needed to get Tearly. In this work, we found another empirical rule that the total number of particles hitting the detector, or TIC, was a good measure of the spectral temperature and, hence, selection of spectra with the same TIC resulted in reproducible spectra. We also succeeded in obtaining reproducible spectra throughout a measurement by controlling TIC near a preset value through feedback adjustment of laser pulse energy. Both TIC selection and TIC control substantially reduced the shot-to-shot spectral variation in a spot, spot-to-spot variation in a sample, and even sample-to-sample variation in MALDI using α-cyano-4-hydroxycinnamic acid or 2,5-dihydroxybenzoic acid as matrix. Based on the utilization of acquired data, TIC control was more efficient than TIC selection by an order of magnitude. Both techniques produced calibration curves with excellent linearity, suggesting their utility in quantification of peptides.

  16. Equation-of-motion coupled-cluster method for doubly ionized states with spin-orbit coupling

    SciTech Connect

    Wang, Zhifan; Hu, Shu; Guo, Jingwei; Wang, Fan

    2015-04-14

    In this work, we report implementation of the equation-of-motion coupled-cluster method for doubly ionized states (EOM-DIP-CC) with spin-orbit coupling (SOC) using a closed-shell reference. Double ionization potentials (DIPs) are calculated in the space spanned by 2h and 3h1p determinants with the EOM-DIP-CC approach at the CC singles and doubles level (CCSD). Time-reversal symmetry together with spatial symmetry is exploited to reduce computational effort. To circumvent the problem of unstable dianion references when diffuse basis functions are included, nuclear charges are scaled. Effect of this stabilization potential on DIPs is estimated based on results from calculations using a small basis set without diffuse basis functions. DIPs and excitation energies of some low-lying states for a series of open-shell atoms and molecules containing heavy elements with two unpaired electrons have been calculated with the EOM-DIP-CCSD approach. Results show that this approach is able to afford a reliable description on SOC splitting. Furthermore, the EOM-DIP-CCSD approach is shown to provide reasonable excitation energies for systems with a dianion reference when diffuse basis functions are not employed.

  17. Computational Calculation Of The Ionization Energies Of The Human Prion Protein By The Coarse-grain Method

    NASA Astrophysics Data System (ADS)

    Lyu, Justin; Andrianarijaona, V. M.

    2016-05-01

    The causes of the misfolding of prion protein -i.e. the transformation of PrPC to PrPSc - have not been clearly elucidated. Many studies have focused on identifying possible chemical conditions, such as pH, temperature and chemical denaturation, that may trigger the pathological transformation of prion proteins (Weiwei Tao, Gwonchan Yoon, Penghui Cao, `` β-sheet-like formation during the mechanical unfolding of prion protein'', The Journal of Chemical Physics, 2015, 143, 125101). Here, we attempt to calculate the ionization energies of the prion protein, which will be able to shed light onto the possible causes of the misfolding. We plan on using the coarse-grain method which allows for a more feasible calculation time by means of approximation. We believe that by being able to approximate the ionization potential, particularly that of the regions known to form stable β-strands of the PrPSc form, the possible sources of denaturation, be it chemical or mechanical, may be narrowed down.

  18. Genome Wide Evaluation of Normal Human Tissue in Response to Controlled, In vivo Low-Dose Low LET Ionizing Radiation Exposure: Pathways and Mechanisms Final Report, September 2013

    SciTech Connect

    Rocke, David M.

    2013-09-09

    During course of this project, we have worked in several areas relevant to low-dose ionizing radiation. Using gene expression to measure biological response, we have examined the response of human skin exposed in-vivo to radation, human skin exposed ex-vivo to radiation, and a human-skin model exposed to radiation. We have learned a great deal about the biological response of human skin to low-dose ionizing radiation.

  19. N-alkylpyridinium quaternization combined with liquid chromatography-electrospray ionization-tandem mass spectrometry: A highly sensitive method to quantify fatty alcohols in thyroid tissues.

    PubMed

    Cao, Yanjing; Guan, Qing; Sun, Tuanqi; Wang, Hang; Leng, Jiapeng; Guo, Yinlong

    2014-11-07

    A highly sensitive method was developed for the identification and quantification of fatty alcohols in biological tissues. In the presence of pyridine-d0 and triflic anhydride (Tf2O), fatty alcohols were converted into permanently charged N-alkylpyridinium ions. Stable isotope-labeled derivatives were generated by pyridine-d5 and added as internal standard (IS). The mixture was analyzed by liquid chromatography coupled to positive electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). This method was optimized and validated in terms of reaction time, derivatization efficiency, stability, desalting, and ion suppression effect. Besides, fatty alcohols exhibited good linear relationship (r(2)>0.993) over the concentration range of 10 ngmL(-1)-1 μgmL(-1). The limits of detection (LODs) were lowered from previously reported 0.1 ngmL(-1) to 0.25 pgmL(-1). Precision (RSD%<15.6%), accuracy (93.0-107.2%), matrix effect, and recovery (in thyroid tissues) were validated as well. Finally, this method was applied for the analysis of ten even carbon-numbered fatty alcohols (C8-C24) in human thyroid carcinoma and para-carcinoma tissues, revealing a significant decrease of fatty alcohols (free and esterified) in thyroid carcinoma tissues (p<0.05).

  20. THORs Power Method for Hydrokinetic Devices - Final Report

    SciTech Connect

    J. Turner Hunt; Joel Rumker

    2012-08-08

    Ocean current energy represents a vast untapped source of renewable energy that exists on the outer continental shelf areas of the 5 major continents. Ocean currents are unidirectional in nature and are perpetuated by thermal and salinity sea gradients, as well as coriolis forces imparted from the earth's rotation. This report details THORs Power Method, a breakthrough power control method that can provide dramatic increases to the capacity factor over and above existing marine hydrokinetic (MHK) devices employed in the extraction of energy from ocean currents. THORs Power Method represents a constant speed, variable depth operational method that continually locates the ocean current turbine at a depth at which the rated power of the generator is routinely achieved. Variable depth operation is achieved by using various vertical force effectors, including ballast tanks for variable weight, a hydrodynamic wing for variable lift or down force and drag flaps for variable vehicle drag forces.

  1. A Survey of Methods of Teaching Mathematics. Final Report.

    ERIC Educational Resources Information Center

    Kovach, L. D.

    Several methods of teaching college-level mathematics sequences are examined for their advantages, disadvantages, and costs. Materials considered include textbooks, film sequences, videotaped lectures, and individualized teaching machines. (SD)

  2. Spectral methods applied to fluidized bed combustors. Final report

    SciTech Connect

    Brown, R.C.; Christofides, N.J.; Junk, K.W.; Raines, T.S.; Thiede, T.D.

    1996-08-01

    The objective of this project was to develop methods for characterizing fuels and sorbents from time-series data obtained during transient operation of fluidized bed boilers. These methods aimed at determining time constants for devolatilization and char burnout using carbon dioxide (CO{sub 2}) profiles and from time constants for the calcination and sulfation processes using CO{sub 2} and sulfur dioxide (SO{sub 2}) profiles.

  3. Final Report: Symposium on Adaptive Methods for Partial Differential Equations

    SciTech Connect

    Pernice, Michael; Johnson, Christopher R.; Smith, Philip J.; Fogelson, Aaron

    1998-12-08

    Complex physical phenomena often include features that span a wide range of spatial and temporal scales. Accurate simulation of such phenomena can be difficult to obtain, and computations that are under-resolved can even exhibit spurious features. While it is possible to resolve small scale features by increasing the number of grid points, global grid refinement can quickly lead to problems that are intractable, even on the largest available computing facilities. These constraints are particularly severe for three dimensional problems that involve complex physics. One way to achieve the needed resolution is to refine the computational mesh locally, in only those regions where enhanced resolution is required. Adaptive solution methods concentrate computational effort in regions where it is most needed. These methods have been successfully applied to a wide variety of problems in computational science and engineering. Adaptive methods can be difficult to implement, prompting the development of tools and environments to facilitate their use. To ensure that the results of their efforts are useful, algorithm and tool developers must maintain close communication with application specialists. Conversely it remains difficult for application specialists who are unfamiliar with the methods to evaluate the trade-offs between the benefits of enhanced local resolution and the effort needed to implement an adaptive solution method.

  4. An Evaluation of the New Approach Method--Final Report.

    ERIC Educational Resources Information Center

    Powers, Donald E.

    The New Approach Method (NAM) is an innovative reading program relying heavily on a phonics approach. The mode of presentation is a cassette tape recorder, which the child is taught to operate at the beginning of the program. The NAM lessons were administered to children at four NAM mini centers; a group of parents administered the NAM lessons to…

  5. Using multivariate statistical methods to model the electrospray ionization response of GXG tripeptides based on multiple physicochemical parameters.

    PubMed

    Raji, M A; Frycák, P; Temiyasathit, C; Kim, S B; Mavromaras, G; Ahn, J-M; Schug, K A

    2009-07-01

    Response factors were determined for twelve GXG peptides (where G stands for glycine and X is any of alanine [A], arginine [R], asparagine [N], aspartic acid [D], glycine [G], histidine [H], leucine [L], lysine [K], phenylalanine [F], serine [S], tyrosine [Y], valine [V]) by electrospray ionization mass spectrometry (ESI-MS). The response factors were measured using a novel flow injection method. This new method is based on the Gaussian distribution of analyte concentration resulting from band-broadening dispersion experienced by the analyte upon passage through an extended volume of PEEK tubing. This method removes the need for preparing a discrete series of standard solutions to assess concentration-dependent response. Relative response factors were calculated for each peptide with reference to GGG. The observed trends in the relative response factors were correlated with several analyte physicochemical parameters, chosen based on current understanding of ion release from charged droplets during the ESI process. These include analyte properties: nonpolar surface area; polar surface area; gas-phase basicity; proton affinity; and Log D. Multivariate statistical analysis using multiple linear regression, decision tree, and support vector regression models were investigated to assess their potential for predicting ESI response based on the analyte properties. The support vector regression model was more versatile and produced the least predictive error following 12-fold cross-validation. The effect of variation in solution pH on the relative response factors is highlighted, as evidenced by the different predictive models obtained for peptide response at two pH values (pH = 6.0 and 9.0). The relationship between physicochemical parameters and associated ionization efficiencies for GXG tripeptides is discussed based on the equilibrium partitioning model. Copyright 2009 John Wiley & Sons, Ltd.

  6. Development and validation of a gas chromatography-flame ionization detection method for quantifying sucrose in equine serum.

    PubMed

    Hewetson, Michael; Aaltonen, Kaisa; Tulamo, Riitta-Mari; Sankari, Satu

    2014-03-01

    A simple and accurate method for quantifying sucrose in equine serum that can be applied to sucrose permeability testing in the horse was developed and validated using gas chromatography with flame ionization detection. The assay provided an acceptable degree of linearity, accuracy, and precision at concentrations of sucrose as low as 2.34 μmol/l and as high as 20.45 μmol/l. Percentage recovery of sucrose from serum ranged from 89% to 102%; repeatability and intermediate precision (relative standard deviation) ranged from 3.6% to 6.7% and 4.1% to 9.3%, respectively. The limit of detection was 0.73 μmol/l. No interfering peaks were observed except lactose, which gave 2 peaks, one of which overlapped partially with sucrose. To evaluate the suitability of the method for quantifying sucrose in serum samples from horses with naturally occurring gastric ulceration, 10 horses with and without naturally occurring gastric ulceration were subjected to sucrose permeability testing. All horses demonstrated an increase in serum sucrose concentration over time following oral administration of sucrose; however, the increase from baseline was significant for horses with gastric ulceration at 45 min (P = 0.0082) and 90 min (P = 0.0082) when compared with healthy horses. It was concluded that gas chromatography with flame ionization detection is a valid method for quantifying sucrose in equine serum and can be applied directly to the analysis of sucrose in equine serum as part of a larger validation study aimed at developing a blood test for the diagnosis of gastric ulcers in horses.

  7. Energy-economy study methods and transit cases. Final report

    SciTech Connect

    Henderson, C.; Ellis, H.T.

    1981-07-01

    The purpose of this report is to describe energy economy study methods that are now available for practical use. The report discusses methods of estimating energy demands in Chapter II. Three heavy rail transit systems and two bus systems (Chapters III to VII) are described in terms of their development history, physical characteristics, operations, service, and energy demands. Estimates are made for the direct and indirect energy demands for the systems and energy economy studies of hypothetical alternatives for operations, equipment, or facilities are presented for the following systems: PATH (Port Authority Trans-Hudson) rail system; BART (Bay Area Rapid Transit District) rail system; AC Transit (Alameda-Contra Costa Transit District) bus system; Washington Metropolitan Area Transit Authority (WMATA) Metrobus and Metrorail systems. Chapter VIII discusses a number of opportunities to conduct energy economy studies, and presents quantitative data for three comparisons of hypothetical alternatives. Some infomation from actual settings was used. (MCW)

  8. Spectral methods and sum acceleration algorithms. Final report

    SciTech Connect

    Boyd, J.

    1995-03-01

    The principle investigator pursued his investigation of numerical algorithms during the period of the grant. The attached list of publications is so lengthy that it is impossible to describe them in detail. However, the author calls attention to the four articles on sequence acceleration and fourteen more on spectral methods, which fulfill the goals of the original proposal. He also continued his research on nonlinear waves, and wrote a dozen papers on this, too.

  9. [Numerical methods for multi-fluid flows]. Final progress report

    SciTech Connect

    Pozrikidis, C.

    1998-07-21

    The central objective of this research has been to develop efficient numerical methods for computing multi-fluid flows with large interfacial deformations, and apply these methods to study the rheology of suspensions of deformable particles with viscous and non-Newtonian interfacial behavior. The mathematical formulation employs boundary-integral, immersed-boundary, and related numerical methods. Particles of interest include liquid drops with constant surface tension and capsules whose interfaces exhibit viscoelastic and incompressible characteristics. In one family of problems, the author has considered the shear-driven and pressure-driven flow of a suspension of two-dimensional liquid drops with ordered and random structure. In a second series of investigations, the author carried out dynamic simulations of two-dimensional, unbounded, doubly-periodic shear flows with random structure. Another family of problems addresses the deformation of three-dimensional capsules whose interfaces exhibit isotropic surface tension, viscous, elastic, or incompressible behavior, in simple shear flow. The numerical results extend previous asymptotic theories for small deformations and illuminate the mechanism of membrane rupture.

  10. A Reliable and Simple Method for Fabricating a Poly(Dimethylsiloxane) Electrospray Ionization Chip with a Corner-Integrated Emitter

    PubMed Central

    Qian, Xiang; Xu, Jie; Yu, Cilong; Chen, Yan; Yu, Quan; Ni, Kai; Wang, Xiaohao

    2015-01-01

    Monolithically integrated emitters have been increasingly applied to microfluidic devices that are coupled to mass spectrometers (MS) as electrospray ionization sources (ESI). A new method was developed to fabricate a duplicable structure which integrated the emitter into a poly(dimethylsiloxane) chip corner. Two photoresist layers containing a raised base which guaranteed the precise integration of the electrospray tip emitter and ensured that the cutting out of the tip exerted no influence even during repeated prototyping were used to ease the operation of the process. Highly stable ESI-MS performance was obtained and the results were compared with those of a commercial fused-silica capillary source. Furthermore, chip-to-chip and run-to-run results indicated both reliability and reproducibility during repeated fabrication. These results reveal that the proposed chip can provide an ideal ion source for MS across many applications, especially with the perspective to be widely used in portable MS during on-site analysis. PMID:25894936

  11. Hydrogeological-Geophysical Methods for Subsurface Site Characterization - Final Report

    SciTech Connect

    Rubin, Yoram

    2001-01-01

    The goal of this research project is to increase water savings and show better ecological control of natural vegetation by developing hydrogeological-geophysical methods for characterizing the permeability and content of water in soil. The ground penetrating radar (GPR) tool was developed and used as the surface geophysical method for monitoring water content. Initial results using the tool suggest that surface GPR is a viable technique for obtaining precision volumetric water content profile estimates, and that laboratory-derived petrophysical relationships could be applied to field-scale GPR data. A field-scale bacterial transport study was conducted within an uncontaminated sandy Pleistocene aquifer to evaluate the importance of heterogeneity in controlling the transport of bacteria. Geochemical, hydrological, geological, and geophysical data were collected to characterize the site prior to and after chemical and bacterial injection experiments. Study results shows that, even within the fairly uniform shallow marine deposits of the narrow channel focus area, heterogeneity existed that influenced the chemical tracer transport over lateral distances of a few meters and vertical distances of less than a half meter. The interpretation of data suggest that the incorporation of geophysical data with limited hydrological data may provide valuable information about the stratigraphy, log conductivity values, and the spatial correlation structure of log conductivity, which have traditionally been obtainable only by performing extensive and intrusive hydrological sampling.

  12. Workshop on molecular methods for genetic diagnosis. Final technical report

    SciTech Connect

    Rinchik, E.M.

    1997-07-01

    The Sarah Lawrence College Human Genetics Program received Department of Energy funding to offer a continuing medical education workshop for genetic counselors in the New York metropolitan area. According to statistics from the National Society of Genetic Counselors, there are approximately 160 genetic counselors working in the tri-state area (New York, New Jersey, and Connecticut), and many of them had been working in the field for more than 10 years. Thus, there was a real need to offer these counselors an in-depth opportunity to learn the specifics of the major advances in molecular genetics, and, in particular, the new approaches to diagnostic testing for genetic disease. As a result of the DOE Award DE-FG02-95ER62048 ($20,583), in July 1995 we offered the {open_quotes}Workshop on Molecular Methods for Genetic Diagnosis{close_quotes} for 24 genetic counselors in the New York metropolitan area. The workshop included an initial review session on the basics of molecular biology, lectures and discussions on past and current topics in molecular genetics and diagnostic procedures, and, importantly, daily laboratory exercises. Each counselor gained not only background, but also firsthand experience, in the major techniques of biochemical and molecular methods for diagnosing genetic diseases as well as in mathematical and computational techniques involved in human genetics analyses. Our goal in offering this workshop was not to make genetic counselors experts in these laboratory diagnostic techniques, but to acquaint them, by hands-on experience, about some of the techniques currently in use. We also wanted to provide them a technical foundation upon which they can understand and appreciate new technical developments arising in the near future.

  13. Improving Methods of Crop Monitoring with Envisat Data- Final Results

    NASA Astrophysics Data System (ADS)

    Wu, Bingfang; Li, Qiangzi; Jia, Kun; Du, Xin; Meng, Jihua; Zhang, Miao; Dong, Qnghan; Eerens, Herman

    2013-01-01

    The main objectives of this project focus on two issues: crop yield estimation and new crop identification and crop acreage estimation methods based on ENVISAT data. Based on the difference of the water requirement of crop in different stages, the crop growing season was divided into several periods for crop biomass estimation. In each period, multi-year time-series ET data estimated with ETWatch was used to get the maximal ET value, which approximately equals to potential ET. And the water stress scalar was calculated for crop biomass estimation. HI was simulated by the ratio of NDVIpre (the average value of NDVI form emergence to anthesis) and NDVIpost (the average value of NDVI from anthesis to maturity). With the estimated crop biomass and HI, crop yield can be calculated by the follow expression: YIELD = BIOMASS * HI. For crop identification, the fusion data of Envisat ASAR VV polarization backscatter data and HJ satellite multi-spectral data was investigated using different classifiers. Results indicated that fusion data can take full advantage of spectral information of HJ multi-spectral data and the structure sensitivity feature of ASAR VV polarization data. The fusion data enlarges the spectral difference among different classifications and improves crop classification accuracy. Crop classification accuracy with fusion of HJ and ASAR was improved by 5 percent compared to the single HJ CCD data. Crop classification with support vector machine (SVM) classifier using multi-configuration SAR data including ENVISAT ASAR and TerraSAR-X was also investigated in our project. Multi-configuration SAR data achieved satisfactory classification accuracy (best overall accuracy of 91.83%) in the North China Plain. ASAR performed slightly better than TerraSAR data acquired in the same time span for crop classification, while the combination of C- and X-band data was better than the multi-temporal C-band data. Two temporal ASAR data acquired in late jointing and flowering

  14. A review of plant decontamination methods: 1988 Update: Final report

    SciTech Connect

    Remark, J.F.

    1989-01-01

    This document updates the state-of-the-art in decontamination technology since the publication of the previous review (EPRI NP- 1128) in May 1981. A brief description of the corrosion-film characteristics is presented as well as corrosion film differences between a BWR and PWR. The generation transportation, activation, and deposition of the radioisotopes found throughout the reactor coolant system is also discussed. Successful, well executed, decontamination campaigns are always preceded by meticulous planning and careful procedure preparation which include contingency operations. The Decontamination Planning and Preparation Section describes the technical planning steps as well as the methodology that should be followed in order to select the optimum decontamination technique for a specific application. A review of a number of the decontamination methods commercialized since 1980 is presented. The basic mechanism for each process is described as well as specific applications of the technology in the fields. Where possible, results obtained in the field are presented. The information was obtained from industry vendors as well as personnel at the plant locations that have utilized the technology. 72 refs., 5 tabs.

  15. Extending applications of the transient energy function method: Final report

    SciTech Connect

    Fouad, A.A.; Vittal, V.; Ni, Y.X.; Pota, H.R.; Nodehi, K.; Oh, T.K.

    1987-09-01

    Direct transient stability analysis using the Transient Energy Function (TEF) method has made significant strides in the last few years. Reliable and accurate transient stability assessment for large power networks is now possible, at a steadily improved speed. In spite of the substantial progress achieved in Direct Transient Stability Analysis, the technique is still limited to a simple power system model, i.e., the so-called classical model (constant generator voltage, constant impedance loads, etc.). This model, while adequate for first swing transient analysis in many situations, is inadequate in other important ones. Furthermore, some important power system components are not included in the power system model currently used in direct transient stability analysis. Using the equations developed in this study, utility engineers can model generator excitation and high-voltage direct-current systems in direct stability calculations. This capability will broaden and quicken the application of a new, powerful analytic tool for power system planning and operations. 32 refs., 28 figs., 31 tabs.

  16. Research on stochastic power-flow study methods. Final report

    SciTech Connect

    Heydt, G. T.

    1981-01-01

    A general algorithm to determine the effects of uncertainty in bus load and generation on the output of conventional power flow analysis is presented. The use of statistical moments is presented and developed as a means for representing the stochastic process. Statistical moments are used to describe the uncertainties, and facilitate the calculations of single and multivarlate probability density functions of input and output variables. The transformation of the uncertainty through the power flow equations is made by the expansion of the node equations in a multivariate Taylor series about an expected operating point. The series is truncated after the second order terms. Since the power flow equations are nonlinear, the expected values of output quantities is in general not the solution to the conventional load flow problem using expected values of input quantities. The second order transformation offers a correction vector and allows the consideration of larger uncertainties which have caused significant error in the current linear transformation algorithms. Voltage controlled busses are included with consideration of upper and lower limits. The finite reactive power available at generation sites, and fixed ranges of transformer tap movement may have a significant effect on voltage and line power flow statistics. A method is given which considers limitation constraints in the evaluation of all output quantities. The bus voltages, line power flows, transformer taps, and generator reactive power requirements are described by their statistical moments. Their values are expressed in terms of the probability that they are above or below specified limits, and their expected values given that they do fall outside the limits. Thus the algorithm supplies information about severity of overload as well as probability of occurrence. An example is given for an eleven bus system, evaluating each quantity separately. The results are compared with Monte Carlo simulation.

  17. Ionizing radiation

    USDA-ARS?s Scientific Manuscript database

    This chapter gives a comprehensive review on ionizing irradiation of fresh fruits and vegetables. Topics include principles of ionizing radiation, its effects on pathogenic and spoilage microorganisms, shelf-life, sensory quality, nutritional and phytochemical composition, as well as physiologic and...

  18. A State-Specific PCM-DFT method to include dynamic solvent effects in the calculation of ionization energies: Application to DNA bases

    NASA Astrophysics Data System (ADS)

    Muñoz-Losa, Aurora; Markovitsi, Dimitra; Improta, Roberto

    2015-08-01

    A State-Specific PCM-DFT method taking into account dynamical solvent effects in the calculation of ionization energies (IEs) is reported. Mono-methylated nucleobases, representative of DNA blocks, are used as a test case. The accuracy of several functionals is tested, the M05-2X functional providing the most consistent performance. The inclusion of some molecules of the first hydration shell does not significantly affect the computed IE. The obtained vertical and adiabatic IEs are in good agreement with the available experimental and computational results, supporting the reliability of our method, enabling the calculation of first and upper ionization energies by using a single approach.

  19. Method development for the characterization of biofuel intermediate products using gas chromatography with simultaneous mass spectrometric and flame ionization detections.

    PubMed

    Sťávová, Jana; Stahl, Danese C; Seames, Wayne S; Kubátová, Alena

    2012-02-10

    Accurate analytical methods are required to develop and evaluate the quality of new renewable transportation fuels and intermediate organic liquid products (OLPs). Unfortunately, existing methods developed for the detailed characterization of petroleum products, are not accurate for many of the OLPs generated from non-petroleum feedstocks. In this study, a method was developed and applied to the detailed characterization of complex OLPs formed during triacylglyceride (TG) pyrolysis which is the basis for generating one class of emerging biofuels. This method uses gas chromatography coupled simultaneously with flame ionization and mass spectrometry detectors (GC-FID/MS). The FID provided accurate quantification of carbonaceous species while MS enabled identification of unknown compounds. A programed temperature vaporizer using a 25 °C, 0.1 min, 720 °C min(-1), 350 °C, 5 min temperature program is employed which minimizes compound discrimination better than the more commonly utilized split/splitless injector, as verified with injections at 250 and 350 °C. Two standard mixtures featuring over 150 components are used for accurate identification and a designed calibration standard accounts for compound discrimination at the injector and differing FID responses of various classes of compounds. This new method was used to identify and quantify over 250 species in OLPs generated from canola oil, soybean oil, and canola methyl ester (CME). In addition to hydrocarbons, the method was used to quantify polar (upon derivatization) and unidentified species, plus the unresolved complex mixture that has not typically been determined in previous studies. Repeatability of the analytical method was below 5% RSD for all individual components. Using this method, the mass balance was closed for samples derived from canola and soybean oil but only ca. 77 wt% of the OLP generated from CME could be characterized. The ability to close the mass balance depended on sample origin

  20. A method for high-sensitivity peptide sequencing using postsource decay matrix-assisted laser desorption ionization mass spectrometry

    PubMed Central

    Keough, T.; Youngquist, R. S.; Lacey, M. P.

    1999-01-01

    A method has been developed for de novo peptide sequencing using matrix-assisted laser desorption ionization mass spectrometry. This method will facilitate biological studies that require rapid determination of peptide or protein sequences, e.g., determination of posttranslational modifications, identification of active compounds isolated from combinatorial peptide libraries, and the selective identification of proteins as part of proteome studies. The method involves fast, one-step addition of a sulfonic acid group to the N terminus of tryptic peptides followed by acquisition of postsource decay (PSD) fragment ion spectra. The derivatives are designed to promote efficient charge site-initiated fragmentation of the backbone amide bonds and to selectively enhance the detection of a single fragment ion series that contains the C terminus of the molecule (y-ions). The overall method has been applied to pmol quantities of peptides. The resulting PSD fragment ion spectra often exhibit uninterrupted sequences of 20 or more amino acid residues. However, fragmentation efficiency decreases considerably at amide bonds on the C-terminal side of Pro. The spectra are simple enough that de novo sequence tagging is routine. The technique has been successfully applied to peptide mixtures, to high-mass peptides (up to 3,600 Da) and to the unambiguous identification of proteins isolated from two-dimensional gel electrophoresis. The PSD spectra of these derivatized peptides often allow far more selective protein sequence database searches than those obtained from the spectra of native peptides. PMID:10377380

  1. CREATININE DETERMINATION IN URINE BY LIQUID CHROMATOGRAPHY-ELECTROSPRAY IONIZATION-TANDEM MASS SPECTROMETRY METHOD.

    PubMed

    Dereziński, Paweł; Klupczyńska, Agnieszka; Sawicki, Wojciech; Kokot, Zenon J

    2016-01-01

    Creatinine determination in urine is used to estimate the completeness of the 24-h urine collection, compensation for variable diuresis and as a preliminary step in protein profiling in urine. Despite the fact that a wide range of methods of measuring creatinine level in biofluids has been developed, many of them are adversely affected by interfering substances. A new liquid chromatography-tandem mass spectrometry method for creatinine determination in urine has been developed. Chromatographic separation was performed by applying C18 column and a gradient elution. Analyses were carried out on a triple quadrupole mass spectrometer equipped with an electrospray ion source. The developed method was fully validated according to the international guidelines. The quantification range of the method was 5-1500 ng/mL, which corresponds to 1-300 mg/dL in urine. Limit of detection and quantitation were 2 and 5 ng/mL, respectively. Additionally, the comparison of creatinine determination by newly developed method to the colorimetric method was performed. The method enables the determination of creatinine in urine samples with a minimal sample preparation, excellent sensitivity and prominent selectivity. Since mass spectrometry allows to measure a number of compounds simultaneously, a future perspective would be to incorporate the determination of other clinically important compounds excreted in urine.

  2. LDRD Final Report: Adaptive Methods for Laser Plasma Simulation

    SciTech Connect

    Dorr, M R; Garaizar, F X; Hittinger, J A

    2003-01-29

    The goal of this project was to investigate the utility of parallel adaptive mesh refinement (AMR) in the simulation of laser plasma interaction (LPI). The scope of work included the development of new numerical methods and parallel implementation strategies. The primary deliverables were (1) parallel adaptive algorithms to solve a system of equations combining plasma fluid and light propagation models, (2) a research code implementing these algorithms, and (3) an analysis of the performance of parallel AMR on LPI problems. The project accomplished these objectives. New algorithms were developed for the solution of a system of equations describing LPI. These algorithms were implemented in a new research code named ALPS (Adaptive Laser Plasma Simulator) that was used to test the effectiveness of the AMR algorithms on the Laboratory's large-scale computer platforms. The details of the algorithm and the results of the numerical tests were documented in an article published in the Journal of Computational Physics [2]. A principal conclusion of this investigation is that AMR is most effective for LPI systems that are ''hydrodynamically large'', i.e., problems requiring the simulation of a large plasma volume relative to the volume occupied by the laser light. Since the plasma-only regions require less resolution than the laser light, AMR enables the use of efficient meshes for such problems. In contrast, AMR is less effective for, say, a single highly filamented beam propagating through a phase plate, since the resulting speckle pattern may be too dense to adequately separate scales with a locally refined mesh. Ultimately, the gain to be expected from the use of AMR is highly problem-dependent. One class of problems investigated in this project involved a pair of laser beams crossing in a plasma flow. Under certain conditions, energy can be transferred from one beam to the other via a resonant interaction with an ion acoustic wave in the crossing region. AMR provides an

  3. Development of Mass Spectrometric Ionization Methods for Fullerenes and Fullerene Derivatives

    EPA Science Inventory

    Currently investigations into the environmental behavior of fullerenes and fullerene derivatives is hampered by the lack of well characterized standards and by the lack of readily available quantitative analytical methods. Reported herein are investigations into the utility of ma...

  4. Development of Mass Spectrometric Ionization Methods for Fullerenes and Fullerene Derivatives

    EPA Science Inventory

    Currently investigations into the environmental behavior of fullerenes and fullerene derivatives is hampered by the lack of well characterized standards and by the lack of readily available quantitative analytical methods. Reported herein are investigations into the utility of ma...

  5. Electrospray ionization time-of-flight mass spectrum analysis method of polyaluminum chloride flocculants.

    PubMed

    Feng, Chenghong; Bi, Zhe; Tang, Hongxiao

    2015-01-06

    Electrospray mass spectrometry has been reported as a novel technique for Al species identification, but to date, the working mechanism is not clear and no unanimous method exists for spectrum analysis of traditional Al salt flocculants, let alone for analysis of polyaluminum chloride (PAC) flocculants. Therefore, this paper introduces a novel theoretical calculation method to identify Al species from a mass spectrum, based on deducing changes in m/z (mass-to-charge ratio) and molecular formulas of oligomers in five typical PAC flocculants. The use of reference chemical species was specially proposed in the method to guarantee the uniqueness of the assigned species. The charge and mass reduction of the Al cluster was found to proceed by hydrolysis, gasification, and change of hydroxyl on the oxy bridge. The novel method was validated both qualitatively and quantitatively by comparing the results to those obtained with the (27)Al NMR spectrometry.

  6. A gaseous radiochemical method for registration of ionizing radiation and its possible applications in science and economy

    NASA Astrophysics Data System (ADS)

    Lebedev, S. G.; Akulinichev, S. V.; Iljinov, A. S.; Yants, V. E.

    2006-05-01

    This work presents a new possibility of registration of ionizing radiation by the flowing gaseous radiochemical method (FGRM). The specified method uses the property of some solid crystalline lattice materials for a free emission of radioactive isotopes of inert gas atoms formed as a result of nuclear reactions. Generated in an ampoule of the detector, the radioactive inert gases are transported by a gas-carrier into the proportional gas counter of the flowing type, where the decay rate of the radioactive gas species is measured. This quantity is unequivocally related to the flux of particles (neutrons, protons, light and heavy ions) at the location of the ampoule. The method was used to monitor the neutron flux of the pulsed neutron target “RADEX” driven by the linear proton accelerator of INR RAS. Further progress of the FGRM may give rise to possible applications in nuclear physics, astrophysics and medicine, in the nondestructive control of fissionable materials, diagnostics of thermonuclear plasma, monitoring of fluxes and measurement of spectra of bombarding particles.

  7. Rapid Microcystin Determination Using a Paper Spray Ionization Method with a Time-of-Flight Mass Spectrometry System.

    PubMed

    Zhu, Xiaoqiang; Huang, Zhengxu; Gao, Wei; Li, Xue; Li, Lei; Zhu, Hui; Mo, Ting; Huang, Bao; Zhou, Zhen

    2016-07-13

    The eutrophication of surface water sources and climate changes have resulted in an annual explosion of cyanobacterial blooms in many irrigating and drinking water resources. To decrease health risks to the public, a rapid real time method for the synchronous determination of two usually harmful microcystins (MC-RR and MC-LR) in environmental water samples was built by employing a paper spray ionization method coupled with a time-of-flight mass spectrometer system. With this approach, direct analysis of microcystin mixtures without sample preparation has been achieved. Rapid detection was performed, simulating the release process of microcystins in reservoir water samples, and the routine detection frequency was every three minutes. The identification time of microcystins was reduced from several hours to a few minutes. The limit of detection is 1 μg/L, and the limit of quantitation is 3 μg/L. This method displays the ability for carrying out rapid, direct, and high-throughput experiments for determination of microcystins, and it would be of significant interest for environmental and food safety applications.

  8. Sensitive isotope dilution liquid chromatography/electrospray ionization tandem mass spectrometry method for the determination of acrylamide in chocolate.

    PubMed

    Ren, Yiping; Zhang, Yu; Jiao, Jingjing; Cai, Zengxuan; Zhang, Ying

    2006-03-01

    Isotope dilution liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-MS/MS) was applied to the quantification of acrylamide in chocolate matrixes (dark chocolate, milk chocolate, chocolate with nuts, chocolate with almonds, and chocolate with wheat best element). The method included defatting with petroleum ether, extracting with aqueous solution of 2 mol l(-1) sodium chloride and clean-up by solid-phase (SPE) with OASIS HLB 6 cm3 cartridges. Acrylamide was detected with an Atlantis dC18 5 microm 210 x 1.5 mm column using 10% methanol/0.1% formic acid in water as the mobile phase. The analytical method was in-house validated and good results were obtained with respect to repeatability (RSD < 3.5%) and recovery (86-93%), which fulfilled the requirements defined by European Union legislation. The acrylamide levels in chocolate were 23-537 microg kg(-1). Therefore, the method was successfully used for the quantitative analysis of acrlyamide in various chocolate products.

  9. Quasi-simultaneous acquisition of hard electron ionization and soft single-photon ionization mass spectra during GC/MS analysis by rapid switching between both ionization methods: analytical concept, setup, and application on diesel fuel.

    PubMed

    Eschner, Markus S; Gröger, Thomas M; Horvath, Thomas; Gonin, Marc; Zimmermann, Ralf

    2011-05-15

    This work describes the realization of rapid switching between hard electron ionization (EI) and soft single-photon ionization (SPI) integrated in a compact orthogonal acceleration time-of-flight mass spectrometer. Vacuum-ultraviolet (VUV) photons of 9.8 eV (126 nm) emitted from the innovative electron-beam-pumped rare-gas excimer light source (EBEL) filled with argon are focused into the ion chamber by an ellipsoidal mirror optic for accomplishing of SPI. This novel orthogonal acceleration time-of-flight mass spectrometer with switching capability was hyphenated to one-dimensional gas chromatography (GC) and comprehensive two-dimensional (2D) gas chromatography (GC × GC) for the first time. Within this demonstration study, a maximum switching frequency of 80 Hz was applied for investigation of a mineral-oil-type diesel sample. This approach allows the quasi-simultaneous acquisition of complementary information about the fragmentation pattern (EI) as well as the molecular mass (SPI) of compounds within a single analysis. Furthermore, by application of a polar GC column for separation, the SPI data can be displayed in a 2D contour plot, leading to a comprehensive 2D characterization (GC × MS), whereas the typical group-type assignment for diesel is also met.

  10. [A plain method of prediction of visibility of peptides in mass spectrometry with electrospray ionization].

    PubMed

    Rybina, A V; Skvortsov, V S; Kopylov, A T; Zgoda, V G

    2014-01-01

    A new method for screening of essential peptides for protein detection and quantification analysis in the direct positive electrospray mass spectrometry has been proposed. Our method is based on the prediction of the normalized abundance of the mass spectrometric peaks using a linear regression model. This method has the following limitations: (i) selected peptides should be taken so that at pH 2.5 the tested peptides must be presented mainly as the 2+ and 3+ ions; (ii) only peptides having C-terminal lysine or arginine residues are considered. The amino acid composition of the peptide, the peptide concentration, the ratio of the polar surface of peptide to common surface and ratio of the polar volume to common volume are used as independent variables in equation. Several combinations of variables were considered and the best linear regression model had a determination coefficient in leave-one-out validation procedure equal 0.54. This model confidently discriminates peptides with high response ability and peptides with low response ability, and therefore it allows to select only the most promising peptides. This screening method, a plain and fast, can be successfully applied to reduce the list of observed peptides.

  11. Spin-orbit coupling with approximate equation-of-motion coupled-cluster method for ionization potential and electron attachment

    NASA Astrophysics Data System (ADS)

    Cao, Zhanli; Wang, Fan; Yang, Mingli

    2016-10-01

    Various approximate approaches to calculate cluster amplitudes in equation-of-motion coupled-cluster (EOM-CC) approaches for ionization potentials (IP) and electron affinities (EA) with spin-orbit coupling (SOC) included in post self-consistent field (SCF) calculations are proposed to reduce computational effort. Our results indicate that EOM-CC based on cluster amplitudes from the approximate method CCSD-1, where the singles equation is the same as that in CCSD and the doubles amplitudes are approximated with MP2, is able to provide reasonable IPs and EAs when SOC is not present compared with CCSD results. It is an economical approach for calculating IPs and EAs and is not as sensitive to strong correlation as CC2. When SOC is included, the approximate method CCSD-3, where the same singles equation as that in SOC-CCSD is used and the doubles equation of scalar-relativistic CCSD is employed, gives rise to IPs and EAs that are in closest agreement with those of CCSD. However, SO splitting with EOM-CC from CC2 generally agrees best with that with CCSD, while that of CCSD-1 and CCSD-3 is less accurate. This indicates that a balanced treatment of SOC effects on both single and double excitation amplitudes is required to achieve reliable SO splitting.

  12. A method to assess genomic DNA methylation using high-performance liquid chromatography/electrospray ionization mass spectrometry.

    PubMed

    Friso, Simonetta; Choi, Sang-Woon; Dolnikowski, Gregory G; Selhub, Jacob

    2002-09-01

    Eukaryotic DNA is methylated at some cytosine residues, and this epigenetic feature performs critical functions. We developed a method for quantitative determination of 5-methyl-2'-deoxycytidine in human DNA using liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS). The DNA was enzymatically hydrolyzed by sequential digestion with three enzymes. DNA hydrolyzates were subsequently separated by reversed-phase high-performance liquid chromatography in isocratic mode. The four major DNA bases and 5-methyl-2'-deoxycytidine were resolved and eluted in 13 min. Identification of 2'-deoxycytidine and 5-methyl-2'-deoxycytidine was obtained by combined diode array UV spectra analysis and mass spectra of chromatographic peaks. The isotopomers [15N3]-2'-deoxycytidine and (methyl-d3,ring-6-d1)-5-methyl-2'-deoxycytidine were used as internal standards. Ions of m/z 126 and 130 were used to detect 5-methyl-2'-deoxycytidine and its isotopomer, and ions of m/z 112 and 115 were used to detect 2'-deoxycytidine and its stable isotopomer, respectively. The DNA methylation status was calculated on the basis of the amount of 5-methyl-2'-deoxycytidine per microgram of DNA with percent relative standard deviations (%RSD) for a method precision of 7.1 (within-day) and 5.7 (day-to-day). This method also allows the measurement of 5-methyl-2'-deoxycytidine expressed as a percentage of total deoxycytidine residues in genomic DNA with %RSD for method precision of 1.9 (within-day) and 1.7 (day-to-day). This LC/MS method for quantitative determination of genomic DNA methylation status is rapid, sensitive, selective, and precise.

  13. Matrix-assisted laser desorption ionization-time of flight mass spectrometry is a sensitive and specific method for identification of aerococci.

    PubMed

    Senneby, Erik; Nilson, Bo; Petersson, Ann-Cathrine; Rasmussen, Magnus

    2013-04-01

    Conventional methods for the identification of human-pathogenic aerococci to the species level are not reliable. We show that matrix-assisted laser desorption ionization-time of flight mass spectrometry correctly identifies aerococci to the species level and that it can be used to identify aerococci with high specificity in the diagnostic clinical microbiology laboratory.

  14. A SIMPLE AND RAPID MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME OF FLIGHT MASS SPECTROMETRY METHOD TO SCREEN FISH PLASMA SAMPLES FOR ESTROGEN-RESPONSIVE BIOMARKERS

    EPA Science Inventory

    In this study, we describe and evaluate the performance of a simple and rapid mass spectral method for screening fish plasma for estrogen-responsive biomarkers using matrix assisted laster desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) couopled with a short...

  15. A SIMPLE AND RAPID MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME OF FLIGHT MASS SPECTROMETRY METHOD TO SCREEN FISH PLASMA SAMPLES FOR ESTROGEN-RESPONSIVE BIOMARKERS

    EPA Science Inventory

    In this study, we describe and evaluate the performance of a simple and rapid mass spectral method for screening fish plasma for estrogen-responsive biomarkers using matrix assisted laster desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) couopled with a short...

  16. Atmospheric pressure matrix-assisted laser desorption ionization as a plume diagnostic tool in laser evaporation methods

    NASA Astrophysics Data System (ADS)

    Callahan, John H.; Galicia, Marsha C.; Vertes, Akos

    2002-09-01

    Laser evaporation techniques, including matrix-assisted pulsed laser evaporation (MAPLE), are attracting increasing attention due to their ability to deposit thin layers of undegraded synthetic and biopolymers. Laser evaporation methods can be implemented in reflection geometry with the laser and the substrate positioned on the same side of the target. In some applications (e.g. direct write, DW), however, transmission geometry is used, i.e. the thin target is placed between the laser and the substrate. In this case, the laser pulse perforates the target and transfers some target material to the substrate. In order to optimize evaporation processes it is important to know the composition of the target plume and the material deposited from the plume. We used a recently introduced analytical method, atmospheric pressure matrix-assisted laser desorption ionization (AP-MALDI) to characterize the ionic components of the plume both in reflection and in transmission geometry. This technique can also be used to directly probe materials deposited on surfaces (such as glass slides) by laser evaporation methods. The test compound (small peptides, e.g. Angiotensin I, ATI or Substance P) was mixed with a MALDI matrix (α-cyano-4-hydroxycinnamic acid (CHCA), sinapinic acid (SA) or 2,5-dihydroxybenzoic acid (DHB)) and applied to the stainless steel (reflection geometry) or transparent conducting (transmission geometry) target holder. In addition to the classical dried droplet method, we also used electrospray target deposition to gain better control of crystallite size, thickness and homogeneity. The target was mounted in front of the inlet orifice of an ion trap mass spectrometer (IT-MS) that sampled the ionic components of the plume generated by a nitrogen laser. We studied the effect of several parameters, such as, the orifice to target distance, illumination geometry, extracting voltage distribution and sample preparation on the generated ions. Various analyte-matrix and

  17. The Tremaine-Weinberg Method for Pattern Speeds Using Hα Emission from Ionized Gas

    NASA Astrophysics Data System (ADS)

    Beckman, J. E.; Fathi, K.; Piñol, N.; Toonen, S.; Hernandez, O.; Carignan, C.

    2008-10-01

    The Fabry-Perot interferometer FaNTOmM was used at the 3.6-m CFHT and the 1.6-m Mont Mégantic Telescope to obtain data cubes in Hα of 9 nearby spiral galaxies from which maps in integrated intensity, velocity, and velocity dispersion were derived. We then applied the Tremaine-Weinberg method, in which the pattern speed can be deduced from its velocity field, by finding the integrated value of the mean velocity along a slit parallel to the major axis weighted by the intensity and divided by the weighted mean distance of the velocity points from the tangent point measured along the slit. The measured variables can be used either to make separate calculations of the pattern speed and derive a mean, or in a plot of one against the other for all the points on all slits, from which a best fit value can be derived. Linear fits were found for all the galaxies in the sample. For two galaxies a clearly separate inner pattern speed with a higher value, was also identified and measured.

  18. Method for ultra-trace cesium isotope ratio measurements from environmental samples using thermal ionization mass spectrometry

    SciTech Connect

    Snow, Mathew S.; Snyder, Darin C.; Mann, Nick R.; White, Byron M.

    2015-05-01

    135Cs/137Cs isotope ratios can provide the age, origin and history of environmental Cs contamination. Relatively high precision 135Cs/137Cs isotope ratio measurements from samples containing femtogram quantities of 137Cs are needed to accurately track contamination resuspension and redistribution following environmental 137Cs releases; however, mass spectrometric analyses of environmental samples are limited by the large quantities of ionization inhibitors and isobaric interferences which are present at relatively high concentrations in the environment. We report a new approach for Cs purification from environmental samples. An initial ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) column provides a robust method for extracting Cs under a wide variety of sample matrices and mass loads. Cation exchange separations using a second AMP-PAN column result in more than two orders of magnitude greater Cs/Rb separation factors than commercially available strong cation exchangers. Coupling an AMP-PAN cation exchanging step to a microcation column (AG50W resin) enables consistent 2-4% (2σ) measurement errors for samples containing 3-6,000 fg 137Cs, representing the highest precision 135Cs/137Cs ratio measurements currently reported for soil samples at the femtogram level.

  19. Development and Validation of a Method for Alcohol Analysis in Brain Tissue by Headspace Gas Chromatography with Flame Ionization Detector.

    PubMed

    Chun, Hao-Jung; Poklis, Justin L; Poklis, Alphonse; Wolf, Carl E

    2016-10-01

    Ethanol is the most widely used and abused drug. While blood is the preferred specimen for analysis, tissue specimens such as brain serve as alternative specimens for alcohol analysis in post-mortem cases where blood is unavailable or contaminated. A method was developed using headspace gas chromatography with flame ionization detection (HS-GC-FID) for the detection and quantification of ethanol, acetone, isopropanol, methanol and n-propanol in brain tissue specimens. Unfixed volatile-free brain tissue specimens were obtained from the Department of Pathology at Virginia Commonwealth University. Calibrators and controls were prepared from 4-fold diluted homogenates of these brain tissue specimens, and were analyzed using t-butanol as the internal standard. The chromatographic separation was performed with a Restek BAC2 column. A linear calibration was generated for all analytes (mean r(2) > 0.9992) with the limits of detection and quantification of 100-110 mg/kg. Matrix effect from the brain tissue was determined by comparing the slopes of matrix prepared calibration curves with those of aqueous calibration curves; no significant differences were observed for ethanol, acetone, isopropanol, methanol and n-propanol. The bias and the CVs for all volatile controls were ≤10%. The method was also evaluated for carryover, selectivity, interferences, bench-top stability and freeze-thaw stability. The HS-GC-FID method was determined to be reliable and robust for the analysis of ethanol, acetone, isopropanol, methanol and n-propanol concentrations in brain tissue, effectively expanding the specimen options for post-mortem alcohol analysis.

  20. Good Cause Final Rule and Proposal: NESHAP for the Portland Cement Manufacturing Industry: Alternative Monitoring Method

    EPA Pesticide Factsheets

    Withdrawing direct final rule that would have extended approval for the use of an alternative compliance monitoring method for hydrogen chloride (HCl) emissions limits at Portland cement plants and reopening public comment on parallel proposal.

  1. Direct Identification of Urinary Tract Pathogens from Urine Samples, Combining Urine Screening Methods and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

    PubMed

    Íñigo, Melania; Coello, Andreu; Fernández-Rivas, Gema; Rivaya, Belén; Hidalgo, Jessica; Quesada, María Dolores; Ausina, Vicente

    2016-04-01

    Early diagnosis of urinary tract infections (UTIs) is essential to avoid inadequate or unnecessary empirical antibiotic therapy. Microbiological confirmation takes 24 to 48 h. The use of screening methods, such as cytometry and automated microscopic analysis of urine sediment, allows the rapid prediction of negative samples. In addition, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a widely established technique in clinical microbiology laboratories used to identify microorganisms. We evaluated the ability of MALDI-TOF MS to identify microorganisms from direct urine samples and the predictive value of automated analyzers for the identification of microorganisms in urine by MALDI-TOF MS. A total of 451 urine samples from patients with suspected UTIs were first analyzed using the Sysmex UF-1000iflow cytometer, an automatic sediment analyzer with microscopy (SediMax), culture, and then processed by MALDI-TOF MS with a simple triple-centrifuged procedure to obtain a pellet that was washed and centrifuged and finally applied directly to the MALDI-TOF MS plate. The organisms in 336 samples were correctly identified, mainly those with Gram-negative bacteria (86.10%). No microorganisms were misidentified, and noCandidaspp. were correctly identified. Regarding the data from autoanalyzers, the best bacteriuria cutoffs were 1,000 and 200 U/μl for UF-1000iand SediMax, respectively. It was concluded that the combination of a urine screening method and MALDI-TOF MS provided a reliable identification from urine samples, especially in those containing Gram-negative bacteria.

  2. A novel method for analyzing solanesyl esters in tobacco leaves using atmospheric pressure chemical ionization/mass spectrometer.

    PubMed

    Ishida, Naoyuki

    2010-09-10

    A direct and simple method for analyzing solanesyl esters found in tobacco leaves was developed. Sample preparation was performed by accelerated solvent extractor 200 (ASE200) using n-hexane followed by evaporating solution in vacuo and dissolving residue with acetone. The separation of analytes was conducted through high-performance liquid chromatography (HPLC) equipped with an SIL-C18/5C column and the non-aqueous reversed phase chromatography (NARP) technique using acetone and acetonitrile as the mobile phase with a linear gradient. Atmospheric pressure chemical ionization/mass spectrometer (APCI/MS) in positive mode was used to detect solanesyl esters in the following conditions: capillary voltage 4000 V, corona current 10 microA, drying gas flow 5 mL/min, fragmentor voltage 200 V, nebulizer pressure 60 psi, and vaporizer temperature 500 degrees C. Each solanesyl ester was identified by the comparison of analyte with synthesized solanesyl esters. Quantification was conducted by selected ion monitoring (SIM) mode in order to detect the specific product ion (613.6 m/z) fragmented from solanesyl ester. The calibration curve was made in the range of 0.1-40 microg/mL with a regression coefficient over 0.999 on almost all solanesyl esters. The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.01 to 0.05 microg/mL and from 0.03 to 0.15 microg/mL, respectively, on the SIM mode of MS for quantification. Recovery (%) ranged from about 80 to 120%. The direct quantification using the developed method succeeded in showing a different amount and composition of solanesyl esters among various tobacco leaves.

  3. SU-E-T-561: Development of Depth Dose Measurement Technique Using the Multilayer Ionization Chamber for Spot Scanning Method

    SciTech Connect

    Takayanagi, T; Fujitaka, S; Umezawa, M; Ito, Y; Nakashima, C; Matsuda, K

    2014-06-01

    Purpose: To develop a measurement technique which suppresses the difference between profiles obtained with a multilayer ionization chamber (MLIC) and with a water phantom. Methods: The developed technique multiplies the raw MLIC data by a correction factor that depends on the initial beam range and water equivalent depth. The correction factor is derived based on a Bragg curve calculation formula considering range straggling and fluence loss caused by nuclear reactions. Furthermore, the correction factor is adjusted based on several integrated depth doses measured with a water phantom and the MLIC. The measured depth dose profiles along the central axis of the proton field with a nominal field size of 10 by 10 cm were compared between the MLIC using the new technique and the water phantom. The spread out Bragg peak was 20 cm for fields with a range of 30.6 cm and 6.9 cm. Raw MLIC data were obtained with each energy layer, and integrated after multiplying by the correction factor. The measurements were performed by a spot scanning nozzle at Nagoya Proton Therapy Center, Japan. Results: The profile measured with the MLIC using the new technique is consistent with that of the water phantom. Moreover, 97% of the points passed the 1% dose /1mm distance agreement criterion of the gamma index. Conclusion: We have demonstrated that the new technique suppresses the difference between profiles obtained with the MLIC and with the water phantom. It was concluded that this technique is useful for depth dose measurement in proton spot scanning method.

  4. Effects of ionizing radiation and restraint stress on activity, avoidance conditioning, and stomach ulcers in albino rats. Final report October 1980-December 1981

    SciTech Connect

    Lanum, J.; Blick, D.W.; Campbell, M.E.; Wheeler, T.G.; Koger, S.A.

    1984-03-01

    In an experiment with albino rats, we have tried to model a nuclear attack scenario in which military personnel receiving 600 to 800 rads of ionizing radiation would be making a counterattack under the stress of an emergency situation. We used a dose of radiation that, though higher than the human exposure field, was estimated to be its physiological equivalent. Restraining the rat in an immobile position, a technique previously shown to have stressing qualities for rats, was chosen as an analogy to the stress of being in a war emergency. Activity and conditioned avoidance acquisition were chosen as test responses. Performance in the activity maze was affected only to a minor degree and in the direction of considering irradiation as activating. However, all irradiated groups showed retarded conditioned avoidance acquisition, which can be interpreted as decreased adaptability to a stressful situation. Further, our results support the expectation of performance decrements in the military scenario that could not be predicted by considering ionizing radiation in isolation. On the avoidance task, male rats in the combination stress-irradiation condition showed more failures to respond and longer response latencies than any other group. Female rats, on the other hand, showed shorter escape/avoidance latencies in the combined stress-irradiation condition than in the irradiation condition alone. This sex difference may be useful as a clue for investigating mechanisms of radiation resistance and interactions between stressors.

  5. Clusters: Elucidating the dynamics of ionization events and ensuing reactions in the condensed phase. Final technical report, March 1, 1991--February 28, 1994

    SciTech Connect

    Castleman, A.W. Jr.

    1994-10-01

    Chemical reactions that proceed following either a photophysical or ionizing event, are directly influenced by the mechanisms of energy transfer and dissipation away from the site of absorption. Neighboring solvent or solute molecules can affect this by collisional deactivation (removal of energy), through effects in which dissociating molecules are kept in relatively close proximity for comparatively long periods of time due to the presence of the solvent, and in other ways where the solvent influences the energetics of the reaction coordinate. Research on clusters offers promise of elucidating the molecular details of these processes. The studies have focused on providing critical information on problems in radiation biology through investigations of reactions of molecules which simulate functional groups in biological systems, as they proceed following the absorption of ionizing radiation. The overall objective of the program has been to undertake basic underpinning research that contributes to a quantification of the behavior of radionuclides and pollutants associated with advanced energy activities after these materials emanate from their source and are transferred through the environment to the biota and human receptor. Some of the studies have dealt with the interaction of electromagnetic radiation with matter yielding new data that finds value in assessing photoinduced transformation of pollutants including reactions which take place on aerosol particles, as well as those of species which become transformed into aerosols as a result of their chemical and physical interactions.

  6. IONIZATION CHAMBER

    DOEpatents

    Redman, W.C.; Shonka, F.R.

    1958-02-18

    This patent describes a novel ionization chamber which is well suited to measuring the radioactivity of the various portions of a wire as the wire is moved at a uniform speed, in order to produce the neutron flux traverse pattern of a reactor in which the wire was previously exposed to neutron radiation. The ionization chamber of the present invention is characterized by the construction wherein the wire is passed through a tubular, straight electrode and radiation shielding material is disposed along the wire except at an intermediate, narrow area where the second electrode of the chamber is located.

  7. Diclofenac in municipal wastewater treatment plant: quantification using laser diode thermal desorption--atmospheric pressure chemical ionization--tandem mass spectrometry approach in comparison with an established liquid chromatography-electrospray ionization-tandem mass spectrometry method.

    PubMed

    Lonappan, Linson; Pulicharla, Rama; Rouissi, Tarek; Brar, Satinder K; Verma, Mausam; Surampalli, Rao Y; Valero, José R

    2016-02-12

    Diclofenac (DCF), a prevalent non-steroidal anti-inflammatory drug (NSAID) is often detected in wastewater and surface water. Analysis of the pharmaceuticals in complex matrices is often laden with challenges. In this study a reliable, rapid and sensitive method based on laser diode thermal desorption/atmospheric pressure chemical ionization (LDTD/APCI) coupled with tandem mass spectrometry (MS/MS) has been developed for the quantification of DCF in wastewater and wastewater sludge. An established conventional LC-ESI-MS/MS (liquid chromatography-electrospray ionization-tandem mass spectrometry) method was compared with LDTD-APCI-MS/MS approach. The newly developed LDTD-APCI-MS/MS method reduced the analysis time to 12s in lieu of 12 min for LC-ESI-MS/MS method. The method detection limits for LDTD-APCI-MS/MS method were found to be 270 ng L(-1) (LOD) and 1000 ng L(-1) (LOQ). Furthermore, two extraction procedures, ultrasonic assisted extraction (USE) and accelerated solvent extraction (ASE) for the extraction of DCF from wastewater sludge were compared and ASE with 95.6 ± 7% recovery was effective over USE with 86 ± 4% recovery. The fate and partitioning of DCF in wastewater (WW) and wastewater sludge (WWS) in wastewater treatment plant was also monitored at various stages of treatment in Quebec Urban community wastewater treatment plant. DCF exhibited affinity towards WW than WWS with a presence about 60% of DCF in WW in contrary with theoretical prediction (LogKow=4.51).

  8. Characterization of low molecular weight hydrocarbon oligomers by laser desorption/ionization time-of-flight mass spectrometry using a solvent-free sample preparation method.

    PubMed

    Pruns, Julia K; Vietzke, Jens-Peter; Strassner, Manfred; Rapp, Claudius; Hintze, Ulrich; König, Wilfried A

    2002-01-01

    A new solvent-free sample preparation method using silver trifluoroacetate (AgTFA) was developed for the analysis of low molecular weight paraffins and microcrystalline waxes by laser desorption/ionization time-of-flight mass spectrometry (LDI-TOFMS). Experiments show that spectral quality can be enhanced by dispersing AgTFA directly in liquid paraffins without the use of additional solvents. This preparation mixture is applied directly to the MALDI probe. Solid waxes could be examined by melting prior to analysis. The method also provides sufficiently reproducible spectra that peak area ratios between mono- and bicyclic alkane peaks indicated variations in the cycloalkane content of paraffin samples. Dehydrogenation of hydrocarbons observed during the desorption/ionization process was studied by analysis of alkane standards.

  9. Ambient ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Lebedev, A. T.

    2015-07-01

    Ambient ionization mass spectrometry emerged as a new scientific discipline only about ten years ago. A considerable body of information has been reported since that time. Keeping the sensitivity, performance and informativity of classical mass spectrometry methods, the new approach made it possible to eliminate laborious sample preparation procedures and triggered the development of miniaturized instruments to work directly in the field. The review concerns the theoretical foundations and design of ambient ionization methods. Their advantages and drawbacks, as well as prospects for application in chemistry, biology, medicine, environmetal analysis, etc., are discussed. The bibliography includes 194 references.

  10. Ionization of atoms in strong low-frequency electromagnetic field

    SciTech Connect

    Krainov, V. P.

    2010-08-15

    The ionization of atoms in a low-frequency linearly polarized electromagnetic field (the photon energy is much lower than the ionization potential of an atom) is considered under new conditions, in which the Coulomb interaction of an electron with the atomic core in the final state of the continuum cannot be considered in perturbation theory in the interaction of the electron with the electromagnetic field. The field is assumed to be much weaker that the atomic field. In these conditions, the classical motion of the electron in the final state of the continuum becomes chaotic (so-called dynamic chaos). Using the well-known Chirikov method of averaging over chaotic variations of the phase of motion, the problem can be reduced to non-linear diffusion on the energy scale. We calculate the classical electron energy in the final state, which is averaged over fast chaotic oscillations and takes into account both the Coulomb field and the electromagnetic field. This energy is used to calculate the probability of ionization from the ground state of the atom to a lower-lying state in the continuum using the Landau-Dykhne approximation (to exponential accuracy). This ionization probability noticeably depends on the field frequency. Upon a decrease in frequency, a transition to the well-known tunnel ionization limit with a probability independent of the field frequency is considered.

  11. Comparative study of fourteen alkaloids from Uncaria rhynchophylla hooks and leaves using HPLC-diode array detection-atmospheric pressure chemical ionization/MS method.

    PubMed

    Qu, Jialin; Gong, Tianxing; Ma, Bin; Zhang, Lin; Kano, Yoshihiro; Yuan, Dan

    2012-01-01

    The purpose of the study is to compare alkaloid profile of Uncaria rhynchophylla hooks and leaves. Ten oxindole alkaloids and four glycosidic indole alkaloids were identified using HPLC-diode array detection (DAD) or LC-atmospheric pressure chemical ionization (APCI)-MS method, and a HPLC-UV method for simultaneous quantification of major alkaloids was validated. The hooks are characterized by high levels of four oxindole alkaloids rhynchophylline (R), isorhynchophylline (IR), corynoxeine (C) and isocorynoxeine (IC), while the leaves contained high level of two glycosidic indole alkaloids vincoside lactam (VL) and strictosidine (S). The presented methods have proven its usefulness in chemical characterization of U. rhynchophylla hooks and leaves.

  12. Validated gas chromatographic-negative ion chemical ionization mass spectrometric method for delta(9)-tetrahydrocannabinol in sweat patches.

    PubMed

    Saito, Takeshi; Wtsadik, Abraham; Scheidweiler, Karl B; Fortner, Neil; Takeichi, Sanae; Huestis, Marilyn A

    2004-11-01

    A sensitive gas chromatography-negative ion chemical ionization mass spectrometry (GC/MS-NICI) method was developed and validated for the measurement of Delta(9)-tetrahydrocannabinol (THC) in human sweat patches. THC-d(0) and THC-d(3) were added to worn blank sweat patches (PharmChek; PharmChem Incorporated) and extracted with 3 mL of methanol-0.2 mol/L sodium acetate buffer (pH 5.0, 3:1 by volume) on a reciprocating shaker at ambient temperature for 30 min. Extracted solution (2 mL) was diluted with 8 mL of 0.1 mol/L sodium acetate buffer (pH 4.5) and extracted by use of solid-phase extraction columns (CleanScreen; United Chemical Technologies). Dried extracts were derivatized with trifluoroacetic acid and analyzed with an Agilent 6890 gas chromatograph interfaced with an Agilent 5973 mass selective detector operated in NICI-selected ion-monitoring mode. The lower limits of detection and quantification for THC in human sweat were 0.2 and 0.4 ng/patch, respectively. The calibration curve was linear from 0.4 to 10 ng/patch (R(2) >0.995). Overall recovery of THC from blank worn patches to which 0.6, 4.0, and 8.0 ng of THC had been added was 44-46%. Assay imprecision, expressed as CV, was <10% for 0.6, 4.0, and 8.0 ng/patch quality-control samples. Twenty-one potential interfering compounds (50 ng/patch) added to low quality-control samples (0.6 ng/patch) did not influence THC quantification. This GC/MS-NICI assay for THC in human sweat provides adequate sensitivity and performance characteristics for analyzing THC in sweat patches and meets the requirements of the proposed Substance Abuse and Mental Health Administration's guidelines for sweat testing.

  13. Matrix-assisted laser desorption/ionization mass spectrometry method for selectively producing either singly or multiply charged molecular ions.

    PubMed

    Trimpin, Sarah; Inutan, Ellen D; Herath, Thushani N; McEwen, Charles N

    2010-01-01

    Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is noted for its ability to produce primarily singly charged ions. This is an attribute when using direct ionization for complex mixtures such as protein digests or synthetic polymers. However, the ability to produce multiply charged ions, as with electrospray ionization (ESI), has advantages such as extending the mass range on mass spectrometers with limited mass-to-charge (m/z) range and enhancing fragmentation for structural characterization. We designed and fabricated a novel field free transmission geometry atmopsheric pressure (AP) MALDI source mounted to a high-mass resolution Orbitrap Exactive mass spectrometer. We report the ability to produce at will either singly charged ions or highly charged ions using a MALDI process by simply changing the matrix or the matrix preparation conditions. Mass spectra with multiply charged ions very similar to those obtained with ESI of proteins such as cytochrome c and ubiquitin are obtained with low femtomole amounts applied to the MALDI target plate and for peptides such as angiotensin I and II with application of attomole amounts. Single scan acquisitions produce sufficient ion current even from proteins.

  14. Technical Note: A direct ray-tracing method to compute integral depth dose in pencil beam proton radiography with a multilayer ionization chamber.

    PubMed

    Farace, Paolo; Righetto, Roberto; Deffet, Sylvain; Meijers, Arturs; Vander Stappen, Francois

    2016-12-01

    To introduce a fast ray-tracing algorithm in pencil proton radiography (PR) with a multilayer ionization chamber (MLIC) for in vivo range error mapping. Pencil beam PR was obtained by delivering spots uniformly positioned in a square (45 × 45 mm(2) field-of-view) of 9 × 9 spots capable of crossing the phantoms (210 MeV). The exit beam was collected by a MLIC to sample the integral depth dose (IDDMLIC). PRs of an electron-density and of a head phantom were acquired by moving the couch to obtain multiple 45 × 45 mm(2) frames. To map the corresponding range errors, the two-dimensional set of IDDMLIC was compared with (i) the integral depth dose computed by the treatment planning system (TPS) by both analytic (IDDTPS) and Monte Carlo (IDDMC) algorithms in a volume of water simulating the MLIC at the CT, and (ii) the integral depth dose directly computed by a simple ray-tracing algorithm (IDDdirect) through the same CT data. The exact spatial position of the spot pattern was numerically adjusted testing different in-plane positions and selecting the one that minimized the range differences between IDDdirect and IDDMLIC. Range error mapping was feasible by both the TPS and the ray-tracing methods, but very sensitive to even small misalignments. In homogeneous regions, the range errors computed by the direct ray-tracing algorithm matched the results obtained by both the analytic and the Monte Carlo algorithms. In both phantoms, lateral heterogeneities were better modeled by the ray-tracing and the Monte Carlo algorithms than by the analytic TPS computation. Accordingly, when the pencil beam crossed lateral heterogeneities, the range errors mapped by the direct algorithm matched better the Monte Carlo maps than those obtained by the analytic algorithm. Finally, the simplicity of the ray-tracing algorithm allowed to implement a prototype procedure for automated spatial alignment. The ray-tracing algorithm can reliably replace the TPS method in MLIC PR for in vivo range

  15. Analysis of the Methods Used for Identifying Potential School Dropouts. Final Report.

    ERIC Educational Resources Information Center

    Neyman, C. A., Jr.

    This final report analyzes the research methods used in the identification of potential dropouts. This program was administered under Title I (ESEA, 1965) in the District of Columbia (see also ED 049 319). Three forms were used in the evaluation of Title I students identified as potential dropouts during the school year 1967-68: (1) Student…

  16. Writing Cover Letters That Address Instructor Feedback Improves Final Papers in a Research Methods Course

    ERIC Educational Resources Information Center

    Daniel, Frances; Gaze, Catherine M.; Braasch, Jason L. G.

    2015-01-01

    We examined how writing cover letters to the instructor influenced final papers in research methods courses. After receiving instructor feedback on drafts of each section of an American Psychological Association style research paper throughout the semester, students in two classes wrote cover letters to the instructor explaining how the instructor…

  17. Assessment of Methods for Estimating Risk to Birds from Ingestion of Contaminated Grit Particles (Final Report)

    EPA Science Inventory

    The U.S. EPA Ecological Risk Assessment Support Center (ERASC) announced the release of the final report entitled, Assessment of Methods for Estimating Risk to Birds from Ingestion of Contaminated Grit Particles. This report evaluates approaches for estimating the probabi...

  18. Writing Cover Letters That Address Instructor Feedback Improves Final Papers in a Research Methods Course

    ERIC Educational Resources Information Center

    Daniel, Frances; Gaze, Catherine M.; Braasch, Jason L. G.

    2015-01-01

    We examined how writing cover letters to the instructor influenced final papers in research methods courses. After receiving instructor feedback on drafts of each section of an American Psychological Association style research paper throughout the semester, students in two classes wrote cover letters to the instructor explaining how the instructor…

  19. Assessment of Methods for Estimating Risk to Birds from Ingestion of Contaminated Grit Particles (Final Report)

    EPA Science Inventory

    The U.S. EPA Ecological Risk Assessment Support Center (ERASC) announced the release of the final report entitled, Assessment of Methods for Estimating Risk to Birds from Ingestion of Contaminated Grit Particles. This report evaluates approaches for estimating the probabi...

  20. New design of high performance ionizing bar

    NASA Astrophysics Data System (ADS)

    Wang, Ronggang; Sun, Yurong

    2013-03-01

    This paper introduces a new design of DC-pulse ionizing bar to solve the problem of imbalance offset voltage for the AC ionizing bar, which is easily affected by the environment, as well as indicate the final tests. The new design mainly includes five parts: power supply circuit, main control unit, logic circuit, high frequency transformer unit, and feedback unit. The ionizing bar can automatically adjust the discharge voltage, pulse frequency and pulse width to balance the positive and negative ions. The final test results indicate that the DC ionizing bar owns good effect in electrostatic elimination.

  1. The NASA digital VGH program. Exploration of methods and final results. Volume 1: Development of methods

    NASA Technical Reports Server (NTRS)

    Crabill, Norman L.

    1989-01-01

    Two hundred hours of Lockheed L 1011 digital flight data recorder data taken in 1973 were used to develop methods and procedures for obtaining statistical data useful for updating airliner airworthiness design criteria. Five thousand hours of additional data taken in 1978 to 1982 are reported in volumes 2, 3, 4 and 5.

  2. Determination of a three-step excitation and ionization scheme for resonance ionization and ultratrace analysis of Np-237

    NASA Astrophysics Data System (ADS)

    Raeder, S.; Stöbener, N.; Gottwald, T.; Passler, G.; Reich, T.; Trautmann, N.; Wendt, K.

    2011-03-01

    The long-lived radio isotope 237Np is generated within the nuclear fuel cycle and represents a major hazard in the final disposal of nuclear waste. Related geochemical research requires sensitive methods for the detection of ultratrace amounts of neptunium in environmental samples. Resonance ionization mass spectrometry (RIMS) has proven to be one of the most sensitive methods for the detection of plutonium. A precondition for the application of RIMS to ultratrace analysis of neptunium is the knowledge of an efficient and selective scheme for optical excitation and ionization. Therefore, a multitude of medium to high-lying atomic levels in neptunium was located by applying in-source resonance ionization spectroscopy. By using excitation via six previously known first excited, intermediate levels of odd parity, a set of twelve so far unknown high-lying levels of even parity were identified and studied further for their suitability in resonant excitation/ionization schemes. Autoionizing resonances for efficient ionization of neptunium atoms were subsequently accessed spectroscopically. Altogether five resonance ionization schemes were investigated and characterized concerning their saturation behavior and relative efficiency. Applying a calibrated sample, an overall efficiency of 0.3 % was determined.

  3. Iron ionization and recombination rates and ionization equilibrium

    NASA Technical Reports Server (NTRS)

    Arnaud, M.; Raymond, J.

    1992-01-01

    In the past few years important progress has been made on the knowledge of ionization and recombination rates of iron, an astrophysically abundant heavy element and a major impurity in laboratory fusion devices. We make a critical review of the existing data on ionization and dielectronic recombination and present new computations of radiative recombination rate coefficients of Fe(+14) through Fe(+25) using the photoionization cross sections of Clark et al. (1986). We provide analytical fits to the recommended data (direct ionization and excitation-autoionization cross sections; radiative and dielectronic recombination rate coefficients). Finally we determine the iron ionic fractions at ionization equilibrium and compare them with previous computations as well as with observational data.

  4. Iron ionization and recombination rates and ionization equilibrium

    NASA Technical Reports Server (NTRS)

    Arnaud, M.; Raymond, J.

    1992-01-01

    In the past few years important progress has been made on the knowledge of ionization and recombination rates of iron, an astrophysically abundant heavy element and a major impurity in laboratory fusion devices. We make a critical review of the existing data on ionization and dielectronic recombination and present new computations of radiative recombination rate coefficients of Fe(+14) through Fe(+25) using the photoionization cross sections of Clark et al. (1986). We provide analytical fits to the recommended data (direct ionization and excitation-autoionization cross sections; radiative and dielectronic recombination rate coefficients). Finally we determine the iron ionic fractions at ionization equilibrium and compare them with previous computations as well as with observational data.

  5. Final state interactions and the transverse structure of the pion using non-perturbative eikonal methods

    SciTech Connect

    Gamberg, Leonard; Schlegel, Marc

    2010-01-18

    In the factorized picture of semi-inclusive hadronic processes the naive time reversal-odd parton distributions exist by virtue of the gauge link which renders it color gauge invariant. The link characterizes the dynamical effect of initial/final-state interactions of the active parton due soft gluon exchanges with the target remnant. Though these interactions are non-perturbative, studies of final-state interaction have been approximated by perturbative one-gluon approximation in Abelian models. We include higher-order contributions by applying non-perturbative eikonal methods incorporating color degrees of freedom in a calculation of the Boer-Mulders function of the pion. Lastly, using this framework we explore under what conditions the Boer Mulders function can be described in terms of factorization of final state interactions and a spatial distribution in impact parameter space.

  6. Final state interactions and the transverse structure of the pion using non-perturbative eikonal methods

    DOE PAGES

    Gamberg, Leonard; Schlegel, Marc

    2010-01-18

    In the factorized picture of semi-inclusive hadronic processes the naive time reversal-odd parton distributions exist by virtue of the gauge link which renders it color gauge invariant. The link characterizes the dynamical effect of initial/final-state interactions of the active parton due soft gluon exchanges with the target remnant. Though these interactions are non-perturbative, studies of final-state interaction have been approximated by perturbative one-gluon approximation in Abelian models. We include higher-order contributions by applying non-perturbative eikonal methods incorporating color degrees of freedom in a calculation of the Boer-Mulders function of the pion. Lastly, using this framework we explore under what conditionsmore » the Boer Mulders function can be described in terms of factorization of final state interactions and a spatial distribution in impact parameter space.« less

  7. Polarization phenomena in multiphoton ionization of atoms.

    NASA Technical Reports Server (NTRS)

    Jacobs, V. L.

    1973-01-01

    The theory of multiphoton ionization for an atomic system of arbitrary complexity is developed using a density matrix formalism. An expression is obtained which determines the differential N-photon ionization cross section as a function of the polarization states of the target atom and the incident radiation. The parameters which characterize the photo-electron angular distribution are related to the general reduced matrix elements for the N-photon transition. Two-photon ionization of unpolarized atoms is treated as an illustration of the use of the theory. The dependence of the multiphoton ionization cross section on the polarization state of the incident radiation, which has been observed in two- and three-photon ionization of Cs, is accounted for by the theory. Finally, the photoelectron spin polarization produced by the multiphoton ionization of unpolarized atoms, like the analogous polarization resulting from single-photon ionization, is found to depend on the circular polarization of the incident radiation.

  8. Polarization phenomena in multiphoton ionization of atoms

    NASA Technical Reports Server (NTRS)

    Jacobs, V. L.

    1973-01-01

    The theory of multiphoton ionization for an atomic system of arbitrary complexity is developed using a density matrix formalism. An expression is obtained which determines the differential N-photon ionization cross section as a function of the polarization states of the target atom and the incident radiation. The parameters which characterize the photoelectron angular distribution are related to the general reduced matrix elements for the N-photon transition. Two-photon ionization of unpolarized atoms is treated as an illustration of the use of the theory. The dependence of the multiphoton ionization cross section on the polarization state of the incident radiation, which has been observed in two- and three-photon ionization of Cs, is accounted for by the theory. Finally, the photoelectron spin polarization produced by the multiphoton ionization of unpolarized atoms, like the analogous polarization resulting from single-photon ionization, is found to depend on the circular polarization of the incident radiation.

  9. Aquatic Plant Control Research Program. Field methods to measure aquatic plant treatment method efficacy. Final report

    SciTech Connect

    Killgore, K.J.; Payne, B.S.

    1984-04-01

    The Aquatic Plant Control Research Program (APCRP) of the U.S. Army Engineer Waterways Experiment Station (WES) is developing field techniques to measure treatment efficacy and to determine site characteristics that influence the treatment efficacy. Treatment efficacy is considered a quantitative determination of the extent and duration of changes in problem aquatic plant populations attributable to the use of a treatment method (i.e., chemical, mechanical, biological, environmental). Depending on the plant species, efficacy can be determined or indicated by changes in biomass, areal distribution, or height of an aquatic plant in response to treatment. Aquatic plant biomass is sampled with a WES aquatic biomass sampler; areal distribution of aquatic plants is determined by aerial photography or with an electronic positioning system; and submersed aquatic plant height is measured with a fathometer (depth recorder) used with an electronic positioning and repositioning system (AGNAV). The APCRP has also developed field techniques to determine site characteristics that influence efficacy using commercially available instrumentation. This instrumentation can be used to measure treatment efficacy and to determine site characteristics simultaneously.

  10. Quantification of gamma-H2AX foci in human lymphocytes: a method for biological dosimetry after ionizing radiation exposure.

    PubMed

    Roch-Lefèvre, Sandrine; Mandina, Tania; Voisin, Pascale; Gaëtan, Gruel; Mesa, Jorge Ernesto Gonzàlez; Valente, Marco; Bonnesoeur, Pierre; García, Omar; Voisin, Philippe; Roy, Laurence

    2010-08-01

    Recent studies have suggested that visualization of gamma-H2AX nuclear foci can be used to estimate exposure to very low doses of ionizing radiation. Although this approach is widely used for various purposes, its suitability for individual human biodosimetry has not yet been assessed. We therefore conducted such an assessment with the help of available software for observing and automatically scoring gamma-H2AX foci. The presence of gamma-H2AX foci was evaluated in human peripheral blood lymphocytes exposed ex vivo to gamma rays in a dose range of 0.02 to 2 Gy. We analyzed the response of gamma-H2AX to ionizing radiation in relation to dose, time after exposure, and individual variability. We constructed dose-effect calibration curves at 0.5, 8 and 16 h after exposure and evaluated the threshold of detection of the technique. The results show the promise of automatic gamma-H2AX scoring for a reliable assessment of radiation doses in a dose range of 0.6 Gy to 2 Gy up to 16 h after exposure. This gamma-H2AX-based assay may be useful for biodosimetry, especially for triage to distinguish promptly among individuals the ones who have received negligible doses from those with significantly exposures who are in need of immediate medical attention. However, additional in vivo experiments are needed for validation.

  11. Investigation of electric field distribution on FAC-IR-300 ionization chamber

    NASA Astrophysics Data System (ADS)

    Mohammadi, S. M.; Tavakoli-Anbaran, H.; Zeinali, H. Z.

    2016-07-01

    One of the important parameters for establishing charge particle equilibrium (CPE) conditions of free-air ionization chamber is an electric field distribution. In this paper, electric field distribution inside the ionization chamber was investigated by finite element method. For this purpose, the effects of adding guard plate and guard strips on the electric field distribution in the ionization chamber were studied. it is necessary to apply a lead box around the ionization chamber body to avoid of scattered radiation effects on the ionization chamber operation, but the lead box changes the electric field distribution. In the following, the effect of lead box on the electric field distribution was studied. Finally, electric field distribution factor (kfield) was calculated by the simulation. The results of the simulation showed that presence of the guard plate and guard strips, and applying a suitable potential to lead box, a convergence of kfield to 1 was achieved.

  12. Development and validation of a liquid chromatographic/electrospray ionization mass spectrometric method for the determination of salidroside in rat plasma: application to the pharmacokinetics study.

    PubMed

    Yu, Sen; Liu, Li; Wen, Tao; Liu, Yuchun; Wang, Dianlei; He, Yuxian; Liang, Yan; Liu, Xiaodong; Xie, Lin; Wang, Guangji; Wei, Wenzhi

    2008-01-01

    A sensitive and specific liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method has been developed and validated for the identification and quantification of salidroside, a major active constituent from Rhodiola rosea L., in rat plasma using helicid as an internal standard. The method involves a simple single-step liquid-liquid extraction with n-butanol. The analytes were separated by isocratic gradient elution on a Shim-pack ODS (4.6 microm, 250 mmx2.0 mm i.d.) column and analyzed in selected ion monitoring (SIM) mode with a negative electrospray ionization (ESI) interface using the respective [M+Cl]- ions, m/z 335 for salidroside, m/z 319 for internal standard. The method was validated over the concentration range of 5-2000 ng/mL for salidroside. Within- and between-batch precision (R.S.D.%) were all within 6% and accuracy ranged from 96 to 112%. The lower limits of quantification was 5 ng/mL. The extraction recovery was on average 86.6% for salidroside. The validated method was used to study the pharmacokinetic profile of salidroside in rat plasma after intravenous and oral administration of salidroside. The bioavailability of salidroside in rats is 32.1%.

  13. Application of the partial-Fourier-transform approach for tunnel ionization of molecules

    NASA Astrophysics Data System (ADS)

    Liu, Mingming; Liu, Yunquan

    2016-04-01

    Combining the partial-Fourier-transform approach with Wenzel-Kramers-Brillouin approximation, we theoretically study the strong-field tunneling ionization of diatomic and polyatomic molecules. First we obtain the analytical expression of momentum distribution at the tunnel exit of diatomic molecules, and then we calculate the alignment-dependent ionization rate at different laser intensities and internuclear distances. We show that the internuclear distance has a significant effect on the alignment dependence of the ionization rate. Using this approach, we can also separate the contributions of each atomic center and show the interference effect between them. Finally, we extend this method to a polyatomic molecule, benzene, as an example.

  14. Development and validation of sensitive method for determination of serum cotinine in smokers and nonsmokers by liquid chromatography/atmospheric pressure ionization tandem mass spectrometry.

    PubMed

    Bernert, J T; Turner, W E; Pirkle, J L; Sosnoff, C S; Akins, J R; Waldrep, M K; Ann, Q; Covey, T R; Whitfield, W E; Gunter, E W; Miller, B B; Patterson, D G; Needham, L L; Hannon, W H; Sampson, E J

    1997-12-01

    We describe a sensitive and specific method for measuring cotinine in serum by HPLC coupled to an atmospheric pressure chemical ionization tandem mass spectrometer. This method can analyze 100 samples/day on a routine basis, and its limit of detection of 50 ng/L makes it applicable to the analysis of samples from nonsmokers potentially exposed to environmental tobacco smoke. Analytical accuracy has been demonstrated from the analysis of NIST cotinine standards and from comparative analyses by both the current method and gas chromatography/high-resolution mass spectrometry. Precision has been examined through the repetitive analysis of a series of bench and blind QC materials. This method has been applied to the analysis of cotinine in serum samples collected as part of the Third National Health and Nutrition Examination Survey (NHANES III).

  15. Multiconfigurational spin tensor electron propagator vertical ionization potentials for O2: Comparison to some other forefront methods using the same basis sets and geometries

    NASA Astrophysics Data System (ADS)

    Heryadi, Dodi; Yeager, Danny L.; Golab, Joseph T.; Nichols, Jeffrey A.

    1995-06-01

    In a recent paper in The Journal of Chemical Physics, we showed the potential energy curves for several cation states of O2 obtained using the multiconfigurational spin tensor electron propagator method (MCSTEP) with a <5s4p3d> basis set. In this communication we present vertical ionization potential calculations to the same O2 states. However, for the results reported here, exactly the same basis sets and geometries are used that were used for two other forefront methods; the coupled-cluster reference electron propagator theory (CC-EPT) and the Fock space multireference coupled-cluster method (FSMRCC). Hence, more direct comparisons and contrasts among these methods are now available.

  16. Comparison of electrospray ionization and atmospheric pressure photoionization liquid chromatography mass spectrometry methods for analysis of ergot alkaloids from endophyte-infected sleepygrass (Achnatherum robustum).

    PubMed

    Jarmusch, Alan K; Musso, Ashleigh M; Shymanovich, Tatsiana; Jarmusch, Scott A; Weavil, Miranda J; Lovin, Mary E; Ehrmann, Brandie M; Saari, Susanna; Nichols, David E; Faeth, Stanley H; Cech, Nadja B

    2016-01-05

    Ergot alkaloids are mycotoxins with an array of biological effects. With this study, we investigated for the first time the application of atmospheric pressure photoionization (APPI) as an ionization method for LC-MS analysis of ergot alkaloids, and compared its performance to that of the more established technique of electrospray ionization (ESI). Samples of the grass Achnatherum robustum infected with the ergot producing Epichloë fungus were extracted using cold methanol and subjected to reserved-phase HPLC-ESI-MS and HPLC-APPI-MS analysis. The ergot alkaloids ergonovine and lysergic acid amide were detected in these samples, and quantified via external calibration. Validation parameters were recorded in accordance with ICH guidelines. A triple quadrupole MS operated in multiple reaction monitoring yielded the lowest detection limits. The performance of APPI and ESI methods was comparable. Both methods were subject to very little matrix interference, with percent recoveries ranging from 82% to 100%. As determined with HPLC-APPI-MS quantification, lysergic acid amide and ergonovine were extracted from an A. robustum sample infected with the Epichloë fungus at concentrations of 1.143±0.051 ppm and 0.2822±0.0071 ppm, respectively. There was no statistically significant difference between these concentrations and those determined using ESI for the same samples.

  17. A new method for differentiating adducts of common drinking water DBPs from higher molecular weight DBPs in electrospray ionization-mass spectrometry analysis.

    PubMed

    Zhai, Hongyan; Zhang, Xiangru

    2009-05-01

    With the presence of bromide in source waters, numerous brominated disinfection byproducts (DBPs) are formed during chlorination. Many of them are polar/highly polar DBPs and thus hard to be detected by gas chromatography mass spectrometry. Electrospray ionization triple quadrupole mass spectrometry (ESI-MS/MS) is reported to be an effective method in finding polar brominated DBPs by setting precursor ion scans of m/z 79 and 81. But as a soft ionization technique, ESI could form adducts of common DBPs, which may complicate ESI-MS/MS spectra and hinder the efforts in finding new brominated DBPs. In this paper, a new method was developed for differentiating adducts of common DBPs from higher molecular weight DBPs. This method was based on the ESI-MS/MS precursor ion scans of the fragments that correspond to the molecular ions of common DBPs. Adducts of common DBPs were selectively detected in the ESI-MS/MS spectra of a simulated drinking water sample. Moreover, the structures of several new brominated DBPs in the sample were tentatively proposed.

  18. “Black Bone” MRI: a potential non-ionizing method for three-dimensional cephalometric analysis—a preliminary feasibility study

    PubMed Central

    Watt-Smith, S R; Golding, S J

    2013-01-01

    Objectives: CT offers a three-dimensional solution to the inaccuracies associated with lateral cephalogram-based cephalometric analysis. However, it is associated with significant concerns regarding ionizing radiation exposure. MRI offers a non-ionizing alternative, but this has been less well investigated. We present a novel gradient echo MRI sequence (“Black Bone”) and highlight the potential of this sequence in cephalometric analysis. Methods: After regional ethics approval, “Black Bone” imaging was obtained in eight patients in whom lateral cephalograms were available. “Black Bone”, T1 and T2 weighted spin echo imaging were obtained in the mid-sagittal plane, and measurements were compared with those obtained on the lateral cephalogram using both the Advantage Windows Workstation (GE Medical Systems, Buckinghamshire, UK) and the Dolphin® cephalometric software (v. 11.5.04.23, Premium; Dolphin Imaging, Chatsworth, CA) by one assessor. Further assessment was made by scoring the ease of landmark identification on a ten-point scale. Results: “Black Bone” imaging surpassed T1 and T2 weighted imaging in terms of cephalometric landmark identification. A number of mid-sagittal cephalometric landmarks could not be clearly identified on T2 weighted imaging, making analysis impossible. Measurements on “Black Bone” demonstrated the smallest discrepancy when compared with those obtained on the lateral cephalogram. The discrepancy seen between measurements completed on mid-sagittal MRI and the lateral cephalogram was compounded by inherent inaccuracies of the lateral cephalogram. The overall mean discrepancy between distance measurements on “Black Bone” imaging and those on the lateral cephalogram was 1–2 mm. Conclusions: Overall, “Black Bone” MRI offered an improved method of cephalometric landmark identification over routine MRI sequences, and provides a potential non-ionizing alternative to CT for three-dimensional cephalometrics. PMID

  19. High performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-MS/ESI) method for simultaneous determination of venlafaxine and its three metabolites in human plasma.

    PubMed

    Liu, Wen; Cai, Hua-Lin; Li, Huan-de

    2007-05-01

    A high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-MS/ESI) method for simultaneous determination of venlafaxine (VEN) and its three metabolites O-desmethylvenlafaxine (ODV), N-desmethylvenlafaxine (NDV) and N,O-didesmethylvenlafaxine (DDV) in human plasma has been developed and validated. Estazolam was used as the internal standard. The compounds and internal standard were extracted from plasma by a liquid-liquid extraction. The HPLC separation of the analytes was performed on a Thermo BDS HYPERSIL C18 (250 mm x 4.6 mm, 5 microm, USA) column, using a gradient elution program with solvents constituted of water (ammonium acetate: 30 mmol/l, formic acid 2.6 mmol/l and trifluoroacetic acid 0.13 mmol/l) and acetonitrile (60:40, V/V) at a flow-rate of 1.0 ml/min. All of the analytes were eluted within 6 min. The compounds were ionized in the electrospray ionization (ESI) ion source of the mass spectrometer and were detected in the selected ion recording (SIR) mode. Calibration curves in spiked whole blood were linear from 4.0-700 ng/ml, 2.0-900 ng/ml, 3.0-800 ng/ml and 2.0-700 ng/ml for VEN, ODV, NDV and DDV, respectively, all of them with coefficients of determination above 0.9991. The average extraction recoveries for all the four analytes were above 77%. The methodology recoveries were higher than 91%. The limits of detection were 0.4, 0.2, 0.3, and 0.2 ng/ml for VEN, ODV, NDV and DDV, respectively. The intra- and inter-day variation coefficients were less than 11%. The method is accurate, sensitive and reliable for the pharmacokinetic study of venlafaxine as well as therapeutic drug monitoring (TDM).

  20. Resonance ionization for analytical spectroscopy

    DOEpatents

    Hurst, George S.; Payne, Marvin G.; Wagner, Edward B.

    1976-01-01

    This invention relates to a method for the sensitive and selective analysis of an atomic or molecular component of a gas. According to this method, the desired neutral component is ionized by one or more resonance photon absorptions, and the resultant ions are measured in a sensitive counter. Numerous energy pathways are described for accomplishing the ionization including the use of one or two tunable pulsed dye lasers.

  1. Extraction Chromatographic Methods in the Sample Preparation Sequence for Thermal Ionization Mass Spectrometric Analysis of Plutonium Isotopes

    SciTech Connect

    Grate, Jay W.; O'Hara, Matthew J.; Farawila, Anne F.; Douglas, Matthew; Haney, Morgan M.; Peterson, Steve L.; Maiti, Tapas C.; Aardahl, Christopher L.

    2011-10-17

    A sample preparation sequence for actinide isotopic analysis by TIMS is described that includes column-based extraction chromatography as the first separation step, followed by anion exchange column separations. The sequence is designed to include a wet ashing step after the extraction chromatography to prevent any leached extractant or oxalic acid eluent reagents from interfering with subsequent separations, source preparation, or TIMS ionization. TEVA-resin and DGA-resin materials, containing extractants that consist only of C, N, O, and H atoms, were investigated for isolation of plutonium. Radiotracer level studies confirmed expected high yields from column-based separation procedures. Femtogram-level studies were carried out with TIMS detection, using multiple isotopic spikes through the separation sequence. Pu recoveries were 87% and 86% for TEVA- and DGA-resins separations respectively. The Pu recoveries from 400 {mu}L anion-exchange column separations were 89% and 93% for trial sequences incorporating TEVA and DGA-resin. Thus, a prior extraction chromatography step in the sequence did not interfere with the subsequent anion exchange separation when a simple wet ash step was carried out in between these column separations. The average measurement efficiency, for Pu, encompassing the chemical separation recoveries and the TIMS ionization efficiency, was 2.73 {+-} 0.77% (2-sigma) for the DGA-resin trials and 2.67 {+-} 0.54% for the TEVA-resin trials, compared to 3.41% and 2.37% (average 2.89%) for two spikes in the experimental set. These compare with an average measurement efficiency of 2.78 {+-} 1.70%, n = 33 from process benchmark analyses using Pu spikes processed through a sequence of oxalate precipitation, wet ash, iron hydroxide precipitation, and anion exchange column separations. We conclude that extraction chromatography can be a viable separation procedure as part of a multistep sequence for TIMS sample preparation.

  2. Positron impact ionization of atomic hydrogen

    SciTech Connect

    Acacia, P.; Campeanu, R.I.; Horbatsch, M.

    1993-05-01

    We will present integrated cross sections for ionization of atomic hydrogen by positrons. These have been calculated in a distorted-wave approximation using energy-dependent effective charges in the final channel as well as static and polarization potentials in the initial channel. We present two models for calculating the energy-dependent effective charges both of which produce results in good agreement with the recent experimental measurements of Spicher et al. This is in contrast to previous distorted-wave calculations which used fixed effective charges as well as classical trajectory calculations. Both of these latter methods produced results which were substantially below ours and the experimental data.

  3. Method and plant for conversion of waste material to stable final products

    SciTech Connect

    Santen, S.; Thornblom, J.

    1985-04-02

    The invention relates to a method and plant for converting waste material containing and/or comprising thermally disintegratable chemcial substances to stable final products such as CO/sub 2/, H/sub 2/O and HCI, the waste material being subjected to a plasma gas of high temperature generated in a plasma generator in order to effect disintegration. The waste material in feedable form is caused to flow through a reaction zone, heated by a plasma gas to at least 2000/sup 0/ C. The reaction zone comprises a cavity burned in a gas-permeable filling in piece form arranged in a reaction chamber, by means of the plasma jet from the plasma generator directed towards and projecting into said filling. An appropriate oxygen potential is maintained in at least the reaction zone such that the disintegration products are continuously converted to stable final products.

  4. Development and validation of an ultra high performance liquid chromatography electrospray ionization tandem mass spectrometry method for the simultaneous determination of selected flavonoids in Ginkgo biloba.

    PubMed

    Pandey, Renu; Chandra, Preeti; Arya, Kamal Ram; Kumar, Brijesh

    2014-12-01

    A rapid and sensitive ultra high performance liquid chromatography electrospray ionization tandem mass spectrometry method was developed and validated for the simultaneous determination of 13 flavonoids in leaf, stem, and fruit extracts of male and female trees of Ginkgo biloba to investigate gender- and age-related variations of flavonoids content. Chromatographic separation was accomplished on an Acquity UPLC BEH C18 column (50 mm × 2.1 mm id, 1.7 μm) in 5 min. Quantitation was performed using negative electrospray ionization mass spectrometry in multiple reaction monitoring mode. The calibration curves of all analytes showed a good linear relationship (r(2) ≥ 0.9977) over the concentration range of 1-1000 ng/mL. The precision evaluated by an intra- and interday study showed RSD ≤ 1.98% and good accuracy with overall recovery in the range from 97.90 to 101.09% (RSD ≤ 1.67%) for all analytes. The method sensitivity expressed as the limit of quantitation was typically 0.25-3.57 ng/mL. The results showed that the total content of 13 flavonoids was higher in the leaf extract of an old male Ginkgo tree compared to young female Ginkgo trees.

  5. Ion chromatography electrospray ionization mass spectrometry method development and investigation of lithium hexafluorophosphate-based organic electrolytes and their thermal decomposition products.

    PubMed

    Kraft, Vadim; Grützke, Martin; Weber, Waldemar; Winter, Martin; Nowak, Sascha

    2014-08-08

    A method based on the coupling of ion chromatography (IC) and electrospray ionization mass spectrometry (ESI-MS) for the separation and determination of thermal decomposition products of LiPF6-based organic electrolytes is presented. The utilized electrolytes, LP30 and LP50, are commercially available and consist of 1mol/l LiPF6 dissolved in ethylene carbonate/dimethyl carbonate and ethylene carbonate/ethyl methyl carbonate, respectively. For the separation method development three ion chromatographic columns with different capacity and stationary phase were used and compared. Besides the known hydrolysis products of lithium hexafluorophosphate, several new organophosphates were separated and identified with the developed IC-ESI-MS method during aging investigations of the electrolytes. The chemical structures were elucidated with IC-ESI-MS/MS.

  6. An extraction method of positive blood cultures for direct identification of Candida species by Vitek MS matrix-assisted laser desorption ionization time of flight mass spectrometry.

    PubMed

    Lavergne, Rose-Anne; Chauvin, Pamela; Valentin, Alexis; Fillaux, Judith; Roques-Malecaze, Christine; Arnaud, Sylvie; Menard, Sandie; Magnaval, Jean-François; Berry, Antoine; Cassaing, Sophie; Iriart, Xavier

    2013-08-01

    Candida spp. are an important cause of nosocomial bloodstream infections. Currently, complete identification of yeasts with conventional methods takes several days. We report here the first evaluation of an extraction method associated with the Vitek MS matrix-assisted laser desorption ionization time of flight mass spectrometry for direct identification of Candida species from positive blood cultures. We evaluated this protocol with blood cultures that were inoculated with reference and routine isolates (eight reference strains, 30 patients isolates and six mixed cultures containing two strains of different Candida species), or from patients with candidemia (28 isolates). This method performed extremely well (97% correct identification) with blood cultures of single Candida spp. and significantly reduced the time of diagnosis. Nevertheless, subculture remains indispensable to test fungal resistance and to detect mixed infections.

  7. Rapid and sensitive method for determining free amino acids in honey by gas chromatography with flame ionization or mass spectrometric detection.

    PubMed

    Nozal, Ma J; Bernal, J L; Toribio, M L; Diego, J C; Ruiz, A

    2004-08-20

    This paper describes a rapid, sensitive and specific method for determination of free amino acids in honey involving a new reaction of derivatization and gas chromatography (GC) with flame ionization (FID) and mass spectrometric (MS) detection. The method allows the determination of 22 free amino acids in honey samples in a short time: 8 and 5 min for GC-FID and GC-MS, respectively. Quantitation was performed using Norvaline as internal standard, with detection limits ranging between 0.112 and 1.795 mg/L by GC-FID and between 0.001 and 0.291 mg/L by GC-MS in the selected-ion monitoring mode. The method was validated and applied to a set of 74 honey samples belonging to four different botanical origins: eucaliptus, rosemary, orange and heather. The statistical treatment of data shows a correct classification of different origins over 90%.

  8. Nonsequential double ionization with mid-infrared laser fields

    NASA Astrophysics Data System (ADS)

    Li, Ying-Bin; Wang, Xu; Yu, Ben-Hai; Tang, Qing-Bin; Wang, Guang-Hou; Wan, Jian-Guo

    2016-11-01

    Using a full-dimensional Monte Carlo classical ensemble method, we present a theoretical study of atomic nonsequential double ionization (NSDI) with mid-infrared laser fields, and compare with results from near-infrared laser fields. Unlike single-electron strong-field processes, double ionization shows complex and unexpected interplays between the returning electron and its parent ion core. As a result of these interplays, NSDI for mid-IR fields is dominated by second-returning electron trajectories, instead of first-returning trajectories for near-IR fields. Some complex NSDI channels commonly happen with near-IR fields, such as the recollision-excitation-with-subsequent-ionization (RESI) channel, are virtually shut down by mid-IR fields. Besides, the final energies of the two electrons can be extremely unequal, leading to novel e-e momentum correlation spectra that can be measured experimentally.

  9. Nonsequential double ionization with mid-infrared laser fields

    PubMed Central

    Li, Ying-Bin; Wang, Xu; Yu, Ben-Hai; Tang, Qing-Bin; Wang, Guang-Hou; Wan, Jian-Guo

    2016-01-01

    Using a full-dimensional Monte Carlo classical ensemble method, we present a theoretical study of atomic nonsequential double ionization (NSDI) with mid-infrared laser fields, and compare with results from near-infrared laser fields. Unlike single-electron strong-field processes, double ionization shows complex and unexpected interplays between the returning electron and its parent ion core. As a result of these interplays, NSDI for mid-IR fields is dominated by second-returning electron trajectories, instead of first-returning trajectories for near-IR fields. Some complex NSDI channels commonly happen with near-IR fields, such as the recollision-excitation-with-subsequent-ionization (RESI) channel, are virtually shut down by mid-IR fields. Besides, the final energies of the two electrons can be extremely unequal, leading to novel e-e momentum correlation spectra that can be measured experimentally. PMID:27857182

  10. Nonsequential double ionization with mid-infrared laser fields

    SciTech Connect

    Li, Ying -Bin; Wang, Xu; Yu, Ben -Hai; Tang, Qing -Bin; Wang, Guang -Hou; Wan, Jian -Guo

    2016-11-18

    Using a full-dimensional Monte Carlo classical ensemble method, we present a theoretical study of atomic nonsequential double ionization (NSDI) with mid-infrared laser fields, and compare with results from near-infrared laser fields. Unlike single-electron strong-field processes, double ionization shows complex and unexpected interplays between the returning electron and its parent ion core. As a result of these interplays, NSDI for mid-IR fields is dominated by second-returning electron trajectories, instead of first-returning trajectories for near-IR fields. Here, some complex NSDI channels commonly happen with near-IR fields, such as the recollision-excitation-with-subsequent-ionization (RESI) channel, are virtually shut down by mid-IR fields. Besides, the final energies of the two electrons can be extremely unequal, leading to novel e-e momentum correlation spectra that can be measured experimentally.

  11. [The research and application of pretreatment method for matrix-assisted laser desorption ionization-time of flight mass spectrometry identification of filamentous fungi].

    PubMed

    Huang, Y F; Chang, Z; Bai, J; Zhu, M; Zhang, M X; Wang, M; Zhang, G; Li, X Y; Tong, Y G; Wang, J L; Lu, X X

    2017-08-08

    Objective: To establish and evaluate the feasibility of a pretreatment method for matrix-assisted laser desorption ionization-time of flight mass spectrometry identification of filamentous fungi developed by the laboratory. Methods: Three hundred and eighty strains of filamentous fungi from January 2014 to December 2016 were recovered and cultured on sabouraud dextrose agar (SDA) plate at 28 ℃ to mature state. Meanwhile, the fungi were cultured in liquid sabouraud medium with a vertical rotation method recommended by Bruker and a horizontal vibration method developed by the laboratory until adequate amount of colonies were observed. For the strains cultured with the three methods, protein was extracted with modified magnetic bead-based extraction method for mass spectrum identification. Results: For 380 fungi strains, it took 3-10 d to culture with SDA culture method, and the ratio of identification of the species and genus was 47% and 81%, respectively; it took 5-7 d to culture with vertical rotation method, and the ratio of identification of the species and genus was 76% and 94%, respectively; it took 1-2 d to culture with horizontal vibration method, and the ratio of identification of the species and genus was 96% and 99%, respectively. For the comparison between horizontal vibration method and SDA culture method comparison, the difference was statistically significant (χ(2)=39.026, P<0.01); for the comparison between horizontal vibration method and vertical rotation method recommended by Bruker, the difference was statistically significant(χ(2)=11.310, P<0.01). Conclusion: The horizontal vibration method and modified magnetic bead-based extraction method developed by the laboratory is superior to the method recommended by Bruker and SDA culture method in terms of the identification capacity for filamentous fungi, which can be applied in clinic.

  12. Can Nonpolar Polyisobutylenes be Measured by Electrospray Ionization Mass Spectrometry? Anion-Attachment Proved to be an Appropriate Method

    NASA Astrophysics Data System (ADS)

    Nagy, Lajos; Nagy, Tibor; Deák, György; Kuki, Ákos; Purgel, Mihály; Narmandakh, Mijid; Iván, Béla; Zsuga, Miklós; Kéki, Sándor

    2016-03-01

    Polyisobutylenes (PIBs) with different end-groups including chlorine, exo-olefin, hydroxyl, and methyl prepared from aliphatic and aromatic initiators were studied by electrospray ionization mass spectrometry (ESI-MS). Independently of the end-groups, presence or absence of aromatic initiator moiety, these PIB derivatives were capable of forming adduct ions with NO3 - and Cl- ions, thus allowing the direct characterization of these compounds in the negative ion mode of ESI-MS. To obtain [PIB + NO3]- and [PIB + Cl]- adduct ions with appreciable intensities, addition of polar solvents such as acetone, 2-propanol, or ethanol to the dichloromethane solution of PIBs was necessary. Furthermore, increasing both the polarity (by increasing the acetone content) and the ion-source temperature give rise to enhanced intensities for both [PIB + NO3]- and [PIB + Cl]- ions. Energy-dependent collision induced dissociation studies (CID) revealed that increasing the collision voltages resulted in the shift of the apparent molecular masses to higher ones. CID studies also showed that dissociation of the [PIB + Cl]- ions requires higher collision energy than that of [PIB + NO3]-. In addition, Density Functional Theory calculations were performed to gain insights into the nature of the interactions between the highly non-polar PIB chains and anions NO3 - and Cl- as well as to determine the zero-point corrected electronic energies for the formation of [PIB + NO3]- and [PIB + Cl]- adduct ions.

  13. Precision treatment of single and double multiphoton ionization of He atoms by strong laser fields: Time-dependent generalized pseudospectral method in internal coordinates

    NASA Astrophysics Data System (ADS)

    Telnov, Dmitry A.; Heslar, John; Chu, Shih-I.

    2012-06-01

    We have developed a new computational method for accurate and efficient numerical solution of the time-dependent Schr"odinger equation for two-electron atoms. Our approach is full-dimensional and makes use of the internal coordinates of the electrons in the plane defined by the electrons and the nucleus (r1, r2, and θ12) as well as Euler angles which determine the orientation of the plane in space. The internal coordinates can be optimally discretized by means of the generalized pseudospectral method while the Euler angles appear through the basis set functions with the definite total angular momentum and its projections. The results of the single and double ionization of the helium atom by strong 800 nm laser fields will be presented. The accurate time-dependent electron density obtained can be used for testing and improvement of various approximate exchange-correlation functionals of the time-dependent density functional theory.

  14. High pressure xenon ionization detector

    DOEpatents

    Markey, J.K.

    1989-11-14

    A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0 to 30 C. 2 figs.

  15. High pressure xenon ionization detector

    DOEpatents

    Markey, John K.

    1989-01-01

    A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0.degree. to 30.degree. C.

  16. A Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Method for the Identification of Anthraquinones: the Case of Historical Lakes.

    PubMed

    Sabatini, Francesca; Lluveras-Tenorio, Anna; Degano, Ilaria; Kuckova, Stepanka; Krizova, Iva; Colombini, Maria Perla

    2016-11-01

    This study deals with the identification of anthraquinoid molecular markers in standard dyes, reference lakes, and paint model systems using a micro-invasive and nondestructive technique such as matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI-ToF-MS). Red anthraquinoid lakes, such as madder lake, carmine lake, and Indian lac, have been the most widely used for painting purposes since ancient times. From an analytical point of view, identifying lakes in paint samples is challenging and developing methods that maximize the information achievable minimizing the amount of sample needed is of paramount importance. The employed method was tested on less than 0.5 mg of reference samples and required a minimal sample preparation, entailing a hydrofluoric acid extraction. The method is fast and versatile because of the possibility to re-analyze the same sample (once it has been spotted on the steel plate), testing both positive and negative modes in a few minutes. The MALDI mass spectra collected in the two analysis modes were studied and compared with LDI and simulated mass spectra in order to highlight the peculiar behavior of the anthraquinones in the MALDI process. Both ionization modes were assessed for each species. The effect of the different paint binders on dye identification was also evaluated through the analyses of paint model systems. In the end, the method was successful in detecting madder lake in archeological samples from Greek wall paintings and on an Italian funerary clay vessel, demonstrating its capabilities to identify dyes in small amount of highly degraded samples. Graphical Abstract ᅟ.

  17. A Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Method for the Identification of Anthraquinones: the Case of Historical Lakes

    NASA Astrophysics Data System (ADS)

    Sabatini, Francesca; Lluveras-Tenorio, Anna; Degano, Ilaria; Kuckova, Stepanka; Krizova, Iva; Colombini, Maria Perla

    2016-11-01

    This study deals with the identification of anthraquinoid molecular markers in standard dyes, reference lakes, and paint model systems using a micro-invasive and nondestructive technique such as matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI-ToF-MS). Red anthraquinoid lakes, such as madder lake, carmine lake, and Indian lac, have been the most widely used for painting purposes since ancient times. From an analytical point of view, identifying lakes in paint samples is challenging and developing methods that maximize the information achievable minimizing the amount of sample needed is of paramount importance. The employed method was tested on less than 0.5 mg of reference samples and required a minimal sample preparation, entailing a hydrofluoric acid extraction. The method is fast and versatile because of the possibility to re-analyze the same sample (once it has been spotted on the steel plate), testing both positive and negative modes in a few minutes. The MALDI mass spectra collected in the two analysis modes were studied and compared with LDI and simulated mass spectra in order to highlight the peculiar behavior of the anthraquinones in the MALDI process. Both ionization modes were assessed for each species. The effect of the different paint binders on dye identification was also evaluated through the analyses of paint model systems. In the end, the method was successful in detecting madder lake in archeological samples from Greek wall paintings and on an Italian funerary clay vessel, demonstrating its capabilities to identify dyes in small amount of highly degraded samples.

  18. Comparison and validation of 2 analytical methods for the determination of free fatty acids in dairy products by gas chromatography with flame ionization detection.

    PubMed

    Mannion, David T; Furey, Ambrose; Kilcawley, Kieran N

    2016-07-01

    Accurate quantification of free fatty acids (FFA) in dairy products is important for quality control, nutritional, antimicrobial, authenticity, legislative, and flavor purposes. In this study, the performance of 2 widely used gas chromatographic flame ionization detection methods for determination of FFA in dairy products differing in lipid content and degree of lipolysis were evaluated. We used a direct on-column approach where the isolated FFA extract was injected directly and a derivatization approach where the FFA were esterified in the injector to methyl esters using tetramethylammonium hydroxide as a catalyst. A comprehensive validation was undertaken to establish method linearity, limits of detection, limits of quantification, accuracy, and precision. Linear calibrations of 3 to 700mg/L (R(2)>0.999) and 20 to 700mg/L (R(2)>0.997), and limits of detection and limits of quantification of 0.7 and 3mg/L and 5 and 20mg/L were obtained for the direct injection on-column and the derivatization method, respectively. Intraday precision of 1.5 to 7.2% was obtained for both methods. The direct injection on-column method had the lower levels of limits of detection and quantification, because FFA are directly injected onto the GC as opposed to the split injection used in the derivatization method. However, the direct injection on-column method experienced accumulative column phase deterioration and irreversible FFA absorption because of the acidic nature of the injection extract, which adversely affected method robustness and the quantification of some longer chain FFA. The derivatization method experienced issues with quantification of butyric acid at low concentrations because of coelution with the injection solvent peak, loss of polyunsaturated FFA due to degradation by tetramethylammonium hydroxide, and the periodic emergence of by-product peaks of the tetramethylammonium hydroxide reaction that interfered with the quantification of some short-chain FFA. The

  19. Overestimation of final height prediction in patients with classical congenital adrenal hyperplasia using the Bayley and Pinneau method.

    PubMed

    Bonfig, Walter; Schwarz, Hans Peter

    2012-01-01

    A typical growth pattern with decreased pubertal growth spurt has been identified in patients with classical congenital adrenal hyperplasia (CAH). To evaluate the accuracy of final height predictions in patients with CAH using the Bayley and Pinneau (B&P) method. Using growth and final height data of 92 patients (57 F/35 M) with CAH due to 21-hydroxylase deficiency (38 SV/54 SW), final height predictions with the B&P method were compared to actual final heights. In females, mean final height was 159.9 +/- 5.3 cm (-1.0 +/- 0.7 SDS) compared to predicted mean final height of 167.9 +/- 10.7 cm (+0.5 +/- 1.7 SDS), p < 0.001, overestimation 7.3 +/- 9.5 cm. In males, mean final height was 170.1 +/- 6 cm (-1.2 +/- 0.8 SDS) compared to predicted mean final height of 185.6 +/- 13.4 cm (+1.2 +/- 1.9 SDS), p < 0.001, overestimation 13.9 +/- 10.8 cm. In classical CAH, final height prediction using the B&P method results in significant overestimation of final height.

  20. A METHOD FOR REGENERATION OF SPENT ELECTROCHEMICAL DECONTAMINATION SOLUTION AND ITS TREATMENT FOR FINAL DISPOSAL

    SciTech Connect

    Davydov, D.Yu.; Davydov, Yu.P.; Toropov, I.G.; John, J.; Rosikova, K.; Motl, A.; Hudson, M.J.; Prazska, M.

    2003-02-27

    This paper describes the method of regeneration of spent electrochemical decontamination solution. The proposed method allows separation of radionuclides and stable metals from spent decontamination solution in a form suitable for final disposal and repeated use of the remaining solution for electrochemical decontamination. Development of this method was based on the results of the speciation studies which showed that Fe(III) can be precipitated in the presence of organic complexing agents, in a form of iron hydroxide, and Ag-110m, Co-60, Mn-54 radionuclides can be coprecipitated on it. In order to verify the conclusions made as a result of the speciation studies, the experiments with electrochemically prepared simulant solution and real solution were carried out. The test results proved that the proposed method can be applied in practice. Treatment of the ultimately spent decontamination solutions can be also made applying iron precipitation, which allows for removal of the bulk amount of contaminants, as the first step. Then, if necessary the remaining radionuclides can be removed by sorption. A series of novel absorbers has been tested for their potential for the sorption removal of the remaining radionuclides from the supernate. The test results showed that most of them were more effective in neutral or alkaline range of pH, however, the high efficiency of the sorption removal can be achieved only after the removal of the oxalic and citric acids from solution.

  1. Photoneutron production of a Siemens Primus linear accelerator studied by Monte Carlo methods and a paired magnesium and boron coated magnesium ionization chamber system.

    PubMed

    Becker, J; Brunckhorst, E; Schmidt, R

    2007-11-07

    When radiotherapy with photon energies greater than 10 MV is performed neutrons contaminate the photon beam. In this paper the neutron contamination of the 15 MV photon mode of the Siemens Primus accelerator was studied. The Monte Carlo code MCNPX was used for the description of the treatment head and treatment room. The Monte Carlo results were verified by studying the photon depth dose curve and beam profiles in a water phantom. After these verifications the locations of neutron production were studied and the neutron source spectrum and strength were calculated. The neutron response of the paired Mg/Ar and MgB/Ar ionization chamber system was calculated and experimentally verified for two experimental set-ups. The paired chamber system allowed us to measure neutrons inside the field borders and allowed rapid and point wise measurement in contrast to other methods of neutron detection.

  2. A Simple and Robust Method for Determining the Number of Basic Sites in Peptides and Proteins using Electrospray Ionization Mass Spectrometry

    PubMed Central

    Flick, Tawnya G.; Merenbloom, Samuel I.; Evan, R. Williams

    2011-01-01

    A solution additive has been discovered that can be used to measure the number of basic sites in a peptide or protein using electrospray ionization (ESI) mass spectrometry. Addition of millimolar amounts of perchloric acid (HClO4) to aqueous solutions that contain peptides or proteins results in the noncovalent adduction of HClO4 molecules to the multiply charged ions formed by ESI. For 18 oligopeptides and proteins, ranging in molecular weight from 0.5 to 18.3 kDa, the sum of the number of protons plus maximum number of HClO4 molecules adducted to the lower charge state ions is equal to the number of basic sites in the molecule. This method provides a rapid means of obtaining information about the composition of a peptide or protein and does not require high-resolution measurements, or any instrumental or experimental modifications. PMID:21338067

  3. Simultaneous determination of cyclophosphamide, ifosfamide, doxorubicin, epirubicin and daunorubicin in human urine using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry: bioanalytical method validation.

    PubMed

    Sottani, Cristina; Rinaldi, Paola; Leoni, Emanuela; Poggi, Guido; Teragni, Cristina; Delmonte, Angelo; Minoia, Claudio

    2008-09-01

    A reversed-phase high-performance liquid chromatography (rp-HPLC) system interfaced with an electrospray ionization (ESI) source coupled to tandem mass spectrometry (MS/MS) was developed and validated for the determination of cyclophosphamide (CP), ifosfamide (IF), daunorubicin (DNR), doxorubicin (DXR), and epirubicin (EPI) in human urine. The analysis of samples containing multiple analytes with a dissimilar range of polarities was carried out using a conventional reversed-phase chromatographic BDS Hypersil C8 column. The analytical run was 15 min. The triple quadrupole mass spectrometer was operated in positive ion mode and multiple reaction monitoring (MRM) was used for drug quantification. The method was validated over a concentration range of 0.2 to 4.0 microg.L(-1) for CP, IF, DXR, EPI and 0.15-2.0 microg.L(-1) for DNR in human urine. The lower limit of quantification (LLOQ) was 0.2 microg.L(-1) for CP, IF, EPI and was set at 0.3 and 0.15 microg.L(-1) for DXR and DNR, respectively. The relative standard deviations (RSD%) were <11.2% for inter- and intra-day precisions. The overall accuracy was also within 114.7% for all analytes at the concentrations of the quality control samples. The potential of ionization suppression resulting from the endogenous biological material on the rp-HPLC/MS/MS method was evaluated and measured. The feasibility of the proposed HPLC/ESI-MS/MS procedure was demonstrated by analyzing urine samples from pharmacy technicians and nurses working in hospitals or personnel employed in drug-manufacturing plants.

  4. Influence of renormalization shielding on the electron-impact ionization process in dense partially ionized plasmas

    SciTech Connect

    Song, Mi-Young; Yoon, Jung-Sik; Jung, Young-Dae

    2015-04-15

    The renormalization shielding effects on the electron-impact ionization of hydrogen atom are investigated in dense partially ionized plasmas. The effective projectile-target interaction Hamiltonian and the semiclassical trajectory method are employed to obtain the transition amplitude as well as the ionization probability as functions of the impact parameter, the collision energy, and the renormalization parameter. It is found that the renormalization shielding effect suppresses the transition amplitude for the electron-impact ionization process in dense partially ionized plasmas. It is also found that the renormalization effect suppresses the differential ionization cross section in the peak impact parameter region. In addition, it is found that the influence of renormalization shielding on the ionization cross section decreases with an increase of the relative collision energy. The variations of the renormalization shielding effects on the electron-impact ionization cross section are also discussed.

  5. Development of a liquid chromatography-electrospray ionization-tandem mass spectrometry method for the simultaneous analysis of intact glucosinolates and isothiocyanates in Brassicaceae seeds and functional foods.

    PubMed

    Franco, P; Spinozzi, S; Pagnotta, E; Lazzeri, L; Ugolini, L; Camborata, C; Roda, A

    2016-01-08

    A new high pressure liquid chromatography-electrospray ionization-tandem mass spectrometry method for the simultaneous determination of glucosinolates, as glucoraphanin and glucoerucin, and the corresponding isothiocyanates, as sulforaphane and erucin, was developed and applied to quantify these compounds in Eruca sativa defatted seed meals and enriched functional foods. The method involved solvent extraction, separation was achieved in gradient mode using water with 0.5% formic acid and acetonitrile with 0.5% formic acid and using a reverse phase C18 column. The electrospray ion source operated in negative and positive mode for the detection of glucosinolates and isothiocyanates, respectively, and the multiple reaction monitoring (MRM) was selected as acquisition mode. The method was validated following the ICH guidelines. Replicate experiments demonstrated a good accuracy (bias%<10%) and precision (CV%<10%). Detection limits and quantification limits are in the range of 1-400ng/mL for each analytes. Calibration curves were validated on concentration ranges from 0.05 to 50μg/mL. The method proved to be suitable for glucosinolates and isothiocyanates determination both in biomasses and in complex matrices such as food products enriched with glucosinolates, or nutraceutical bakery products. In addition, the developed method was applied to the simultaneous determination of glucosinolates and isothiocyanates in bakery product enriched with glucosinolates, to evaluate their thermal stability after different industrial processes from cultivation phases to consumer processing. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Fully validated method for rapid and simultaneous measurement of six antiepileptic drugs in serum and plasma using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry.

    PubMed

    Kuhn, Joachim; Knabbe, Cornelius

    2013-06-15

    Therapeutic drug monitoring (TDM) may be very useful in the clinical management of antiepileptic drug therapy for multiple reasons, such as individual variability, metabolism, genetic factors or drug-drug or drug-food interactions. In addition, TDM is helpful to study the variation in pharmacokinetics that occurs between individuals. Here, we describe a rapid assay using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry to measure the antiepileptic drugs lacosamide, lamotrigine, levetiracetam, primidone, topiramate, and zonisamide. After the addition of internal standards (ISs) and protein precipitation of serum or plasma, 1 μl of sample was separated on a 2.1×50 mm reverse phase column (Waters, Acquity UPLC BEH Phenyl, 1.7 μm). Analytes were then ionized and detected by electrospray ionization mass spectrometry with multiple reaction monitoring. Runtime was 2.5 min per injection. Matrix effects were investigated by systematical ion suppression and in-source fragmentation experiments. The calibration curves of the 6 antiepileptic drugs were linear over the working range between 0.05 and 50 mg/L (r>0.99). The limit of detection (LOD) was <0.05 mg/L, whereas the limit of quantification (LLOQ) was 0.10 mg/L of all drugs measured in the assay. The intraassay and interassay coefficients of variation for all compounds were <15% for very low concentration (0.1 mg/L) and <8% in the clinically relevant concentration range (>1.0 mg/L). Mean recoveries were between 87.8 and 98.6% for all drugs. There were no significant ion suppressions detected at the elution times of the analytes. The mean differences between serum and heparinized plasma values were less than 6% for the 6 antiepileptic drugs. All drugs were stable in serum at -20°C, 4°C, and even at RT for at least 1 month. In summary, a specific and sensitive stable isotope dilution UPLC-MS/MS method was developed and validated for routine clinical monitoring of lacosamide

  7. Photo-ionization rate coefficients for the rare gases

    NASA Astrophysics Data System (ADS)

    Pang, Xuexia

    2005-01-01

    By introducing the converting method from electron-impact ionization cross sections to rate coefficients through using a semi-experiential formula, we try to probe a semi-experiential formula for converting the photo-ionization cross sections into photo-ionization rate coefficient. It"s found that photo-ionization rate coefficient is direct proportion to photo-ionization cross sections, the rate S is related with light resource.

  8. A Post-Final Assignment for the Methods Course: Providing an Incentive to Professional Growth for Future Teachers.

    ERIC Educational Resources Information Center

    Bentley, Michael L.

    This paper describes J. Rosengren's post-final assignment and M. Harmin's truth signs activity that were incorporated into a secondary science methods course for preservice teachers. The strength of the post-final assignment is that it is a strategy for extending student learning past the end of a course and even beyond the initial teaching…

  9. Ionization chamber radial response deconvolution in megavoltage photon beam

    NASA Astrophysics Data System (ADS)

    Kulmala, A.; Tenhunen, M.

    2017-09-01

    The aim of this paper is to study a radial response model as a method, to correct output factor results gathered with ionization chambers of different size and shape in cone collimated RT fields. An enhanced version of a non-parametric super-resolution deconvolution method able to model a radial response function of a small cylinder symmetric ionization chamber is described and demonstrated. The radial response of four ionization chambers with different geometry and radius are estimated using 6 MV photon beam in water at the isocentre plane. Finally the validity of the estimates is tested by applying the response functions to the output factor measurements of 4–20 mm conical collimators. The enhanced method is demonstrated by obtaining the response function characteristics with a spatial uncertainty smaller than 0.1 mm when the distance from chamber axis is larger than 0.5 mm. In all studied ionization chambers, a significant local response maximum is found close to the air cavity boundary. The agreement between the output factor results of different chambers is promising, the largest difference (max—min) in output factor is 4% obtained for the smallest 4 mm cone size.

  10. Identification of viridans streptococci With Matrix-Assisted Laser Desorption & Ionization Time-of-flight Mass Spectrometry by an In-house Method and a Commercially Available System.

    PubMed

    Stingu, Catalina Suzana; Eschrich, Klaus; Thiel, Juliane; Borgmann, Toralf; Schaumann, Reiner; Rodloff, Arne C

    2017-09-01

    Two matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS)-based methods were compared for their ability to identify viridans streptococci. One approach employed a reference database and software developed in-house. All inhouse measurements were performed using an Autoflex II Instrument (Bruker Daltonics GmbH, Germany). The other system, a VITEK-MS (BioMérieux, France) was operated on the commercially available V2.0 Knowledge Base for Clinical Use database. Clinical isolates of viridans streptococci (n=184) were examined. Discrepant results were resolved by 16S rDNA sequencing. Species-level identification percentages were compared by a chi-square test. The in-house method correctly identified 179 (97%) and 175 (95%) isolates to the group and species level respectively. In comparison, the VITEK-MS system correctly identified 145 (79%) isolates to the group and species level. The difference between the two methods was statistically significant at both group and species levels. Using the Autoflex II instrument combined with an extraction method instead of whole cell analysis resulted in more reliable viridans streptococci identification. Our results suggest that combining extraction with powerful analysis software and the careful choice of well-identified strains included into the database was useful for identifying viridans streptococci species. © The Korean Society for Laboratory Medicine.

  11. A method for simultaneous analysis of phytosterols and phytosterol esters in tobacco leaves using non aqueous reversed phase chromatography and atmospheric pressure chemical ionization mass spectrometry detector.

    PubMed

    Ishida, Naoyuki

    2014-05-02

    While numerous analytical methods for phytosterols have been reported, the similar polarity and large molecules of phytosterol esters have made the methods lengthy and complicated. For this reason, an analytical method that could completely separate phytosterol esters including the higher fatty acids such as palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid in addition to phytosterols without preliminary separation was developed. The separation was accomplished by non-aqueous reversed phase chromatography technique using only acetone and acetonitrile. An atmospheric pressure chemical ionization/mass spectrometry detector configured at selected ion monitoring mode was hyphenated with the separation system to detect phytosterols and phytosterol esters. Twenty-four types of these were consequently separated and then identified with their authentic components. The calibration curve was drawn in the range of about 5 to 25,000 ng/mL with a regression coefficient over 0.999. The limit of detection and limit of quantification, respectively, ranged from 0.9 to 3.0 ng/mL and from 3.0 to 11.0 ng/mL. Recovery rates ranged from 80 to 120%. The quantification results were subjected to statistical analysis and hierarchical clustering analysis, and were used to determine the differences in the amounts of phytosterols and phytosterol esters across tobacco leaves. The newly developed method succeeded in clarifying the whole composition of phytosterols and phytosterol esters in tobacco leaves and in explaining compositional differences across the variety of tobacco leaves.

  12. Dating the Martian meteorite Zagami by the 87Rb-87Sr isochron method with a prototype in situ resonance ionization mass spectrometer

    PubMed Central

    Scott Anderson, F; Levine, Jonathan; Whitaker, Tom J

    2015-01-01

    RATIONALE The geologic history of the Solar System builds on an extensive record of impact flux models, crater counts, and ∼270 kg of lunar samples analyzed in terrestrial laboratories. However, estimates of impactor flux may be biased by the fact that most of the dated Apollo samples were only tenuously connected to an assumed geologic context. Moreover, uncertainties in the modeled cratering rates are significant enough to lead to estimated errors for dates on Mars and the Moon of ∼1 Ga. Given the great cost of sample return missions, combined with the need to sample multiple terrains on multiple planets, we have developed a prototype instrument that can be used for in situ dating to better constrain the age of planetary samples. METHODS We demonstrate the first use of laser ablation resonance ionization mass spectrometry for 87Rb-87Sr isochron dating of geological specimens. The demands of accuracy and precision have required us to meet challenges including regulation of the ambient temperature, measurement of appropriate backgrounds, sufficient ablation laser intensity, avoidance of the defocusing effect of the plasma created by ablation pulses, and shielding of our detector from atoms and ions of other elements. RESULTS To test whether we could meaningfully date planetary materials, we have analyzed a piece of the Martian meteorite Zagami. In each of four separate measurements we obtained 87Rb-87Sr isochron ages for Zagami consistent with its published age, and, in both of two measurements that reached completion, we obtained better than 200 Ma precision. Combining all our data into a single isochron with 581 spot analyses gives an 87Rb-87Sr age for this specimen of 360 ±90 Ma. CONCLUSIONS Our analyses of the Zagami meteorite represent the first successful application of resonance ionization mass spectrometry to isochron geochronology. Furthermore, the technique is miniaturizable for spaceflight and in situ dating on other planetary bodies. © 2014 The

  13. Ionization probes of molecular structure and chemistry

    SciTech Connect

    Johnson, P.M.

    1993-12-01

    Various photoionization processes provide very sensitive probes for the detection and understanding of the spectra of molecules relevant to combustion processes. The detection of ionization can be selective by using resonant multiphoton ionization or by exploiting the fact that different molecules have different sets of ionization potentials. Therefore, the structure and dynamics of individual molecules can be studied even in a mixed sample. The authors are continuing to develop methods for the selective spectroscopic detection of molecules by ionization, and to use these methods for the study of some molecules of combustion interest.

  14. Generic gas chromatography-flame ionization detection method for quantitation of volatile amines in pharmaceutical drugs and synthetic intermediates.

    PubMed

    Graffius, Gabriel C; Jocher, Brandon M; Zewge, Daniel; Halsey, Holst M; Lee, Gary; Bernardoni, Frank; Bu, Xiaodong; Hartman, Robert; Regalado, Erik L

    2017-10-06

    Volatile amines are among the most frequently used chemicals in organic and pharmaceutical chemistry. Synthetic route optimization often involves the evaluation of several different amines requiring the development and validation of analytical methods for quantitation of residual amine levels. Herein, a simple and fast generic GC-FID method on an Agilent J&W CP-Volamine capillary column (using either He or H2 as the carrier gas) capable of separating over 25 volatile amines and other basic polar species commonly used in pharmaceutical chemistry workflows is described. This 16min method is successfully applied to the analysis and quantitation of volatile amines in a variety of pharmaceutically-related drugs and synthetic intermediates. Method validation experiments showed excellent analytical performance in linearity, recovery, repeatability, and limit of quantitation and detection. In addition, diverse examples for the application of this method to the simultaneous determination of other amine-related chemicals in reaction mixtures are illustrated, thereby indicating that these GC-FID method conditions can be effectively used as starting point during method development for the analysis of other basic polar species beyond the validated list of amines described in this study. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. NR2 and P3+: Accurate, Efficient Electron-Propagator Methods for Calculating Valence, Vertical Ionization Energies of Closed-Shell Molecules.

    PubMed

    Corzo, H H; Galano, Annia; Dolgounitcheva, O; Zakrzewski, V G; Ortiz, J V

    2015-08-20

    Two accurate and computationally efficient electron-propagator (EP) methods for calculating the valence, vertical ionization energies (VIEs) of closed-shell molecules have been identified through comparisons with related approximations. VIEs of a representative set of closed-shell molecules were calculated with EP methods using 10 basis sets. The most easily executed method, the diagonal, second-order (D2) EP approximation, produces results that steadily rise as basis sets are improved toward values based on extrapolated coupled-cluster singles and doubles plus perturbative triples calculations, but its mean errors remain unacceptably large. The outer valence Green function, partial third-order and renormalized partial third-order methods (P3+), which employ the diagonal self-energy approximation, produce markedly better results but have a greater tendency to overestimate VIEs with larger basis sets. The best combination of accuracy and efficiency with a diagonal self-energy matrix is the P3+ approximation, which exhibits the best trends with respect to basis-set saturation. Several renormalized methods with more flexible nondiagonal self-energies also have been examined: the two-particle, one-hole Tamm-Dancoff approximation (2ph-TDA), the third-order algebraic diagrammatic construction or ADC(3), the renormalized third-order (3+) method, and the nondiagonal second-order renormalized (NR2) approximation. Like D2, 2ph-TDA produces steady improvements with basis set augmentation, but its average errors are too large. Errors obtained with 3+ and ADC(3) are smaller on average than those of 2ph-TDA. These methods also have a greater tendency to overestimate VIEs with larger basis sets. The smallest average errors occur for the NR2 approximation; these errors decrease steadily with basis augmentations. As basis sets approach saturation, NR2 becomes the most accurate and efficient method with a nondiagonal self-energy.

  16. Subcycle electron emission in sequential double ionization by elliptical laser pulses

    NASA Astrophysics Data System (ADS)

    Tong, Ai-Hong; Li, Ying-Bin

    2016-12-01

    Using a classical ensemble method, we have investigated sequential double ionization (SDI) of Ar atoms driven by elliptical laser pulses. The results show that the ion momentum distribution of the Ar atoms depends strongly on the pulse duration. As the pulse duration increases, the ion momentum distribution changes from two bands to four bands and then to six bands and finally to an eight-band structure. Back analysis of double ionization trajectories shows that the variation of the band structure originates from pulse duration dependent multiple ionization bursts of the second electron. Our calculations indicate that the subcycle electron emission in the SDI could be more easily accessed by using elliptical laser pulses with a longer wavelength. Moreover, we show that there is good correspondence between the scaled radial momentum and the ionization time.

  17. Pulse duration dependence of atomic sequential double ionization by circular laser pulses

    NASA Astrophysics Data System (ADS)

    Tong, Aihong; Chen, Liangyuan; Li, Yingbin

    2016-09-01

    Using classical ensemble method, we have investigated the pulse duration dependence of sequential double ionization (SDI) of Ar atoms driven by circularly polarized laser pulses. The results show that the ion momentum distribution of Ar atoms depends strongly on the pulse duration. As the pulse duration increases, the ion momentum distribution changes from single-ring to double-ring structure, and finally to the single-ring structure. Back analysis of double ionization trajectories shows that the variation of the ring structure originates from the dependence of the ionization time of the second electron on the pulse duration. Moreover, our calculations clearly manifest the subcycle electron emission in sequential double ionization by circularly polarized laser pulses.

  18. Statistical Methods and Tools for Uxo Characterization (SERDP Final Technical Report)

    SciTech Connect

    Pulsipher, Brent A.; Gilbert, Richard O.; Wilson, John E.; Hassig, Nancy L.; Carlson, Deborah K.; O'Brien, Robert F.; Bates, Derrick J.; Sandness, Gerald A.; Anderson, Kevin K.

    2004-11-15

    The Strategic Environmental Research and Development Program (SERDP) issued a statement of need for FY01 titled Statistical Sampling for Unexploded Ordnance (UXO) Site Characterization that solicited proposals to develop statistically valid sampling protocols for cost-effective, practical, and reliable investigation of sites contaminated with UXO; protocols that could be validated through subsequent field demonstrations. The SERDP goal was the development of a sampling strategy for which a fraction of the site is initially surveyed by geophysical detectors to confidently identify clean areas and subsections (target areas, TAs) that had elevated densities of anomalous geophysical detector readings that could indicate the presence of UXO. More detailed surveys could then be conducted to search the identified TAs for UXO. SERDP funded three projects: those proposed by the Pacific Northwest National Laboratory (PNNL) (SERDP Project No. UXO 1199), Sandia National Laboratory (SNL), and Oak Ridge National Laboratory (ORNL). The projects were closely coordinated to minimize duplication of effort and facilitate use of shared algorithms where feasible. This final report for PNNL Project 1199 describes the methods developed by PNNL to address SERDP's statement-of-need for the development of statistically-based geophysical survey methods for sites where 100% surveys are unattainable or cost prohibitive.

  19. The effect of muscle, cooking method and final internal temperature on quality parameters of beef roast.

    PubMed

    Modzelewska-Kapituła, Monika; Dąbrowska, Ewa; Jankowska, Barbara; Kwiatkowska, Aleksandra; Cierach, Marek

    2012-06-01

    The aim of the study was to evaluate the influence of cooking conditions (dry air and steam) and final internal temperature (75, 85, 95°C) on the physico-chemical properties of beef infraspinatus (INF) and semimembranosus (SEM) muscles as well as their tenderness and juiciness. Cooking method and temperature influenced moisture, total collagen content in cooked meat and cooking loss, whereas muscle type affected fat, total collagen content and cooking loss. Warner-Bratzler shear force values were affected by cooking method, which also influenced juiciness of roasts. Temperature affected tenderness and juiciness, whereas muscle type influenced juiciness. The most desirable tenderness had INF heated in steam and dry air to 95°C. Processing SEM in dry air to 85 and 95°C lowered the juiciness of the roasts. There were significant correlations between physico-chemical, sensorial and image attributes, however high accuracy of prediction (r(2)>0.8) was achieved only for SEM muscle.

  20. Petroleomics by electrospray ionization FT-ICR mass spectrometry coupled to partial least squares with variable selection methods: prediction of the total acid number of crude oils.

    PubMed

    Terra, Luciana A; Filgueiras, Paulo R; Tose, Lílian V; Romão, Wanderson; de Souza, Douglas D; de Castro, Eustáquio V R; de Oliveira, Mirela S L; Dias, Júlio C M; Poppi, Ronei J

    2014-10-07

    Negative-ion mode electrospray ionization, ESI(-), with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was coupled to a Partial Least Squares (PLS) regression and variable selection methods to estimate the total acid number (TAN) of Brazilian crude oil samples. Generally, ESI(-)-FT-ICR mass spectra present a power of resolution of ca. 500,000 and a mass accuracy less than 1 ppm, producing a data matrix containing over 5700 variables per sample. These variables correspond to heteroatom-containing species detected as deprotonated molecules, [M - H](-) ions, which are identified primarily as naphthenic acids, phenols and carbazole analog species. The TAN values for all samples ranged from 0.06 to 3.61 mg of KOH g(-1). To facilitate the spectral interpretation, three methods of variable selection were studied: variable importance in the projection (VIP), interval partial least squares (iPLS) and elimination of uninformative variables (UVE). The UVE method seems to be more appropriate for selecting important variables, reducing the dimension of the variables to 183 and producing a root mean square error of prediction of 0.32 mg of KOH g(-1). By reducing the size of the data, it was possible to relate the selected variables with their corresponding molecular formulas, thus identifying the main chemical species responsible for the TAN values.

  1. Evaluation of a Semiquantitative Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Method for Rapid Antimicrobial Susceptibility Testing of Positive Blood Cultures.

    PubMed

    Jung, Jette S; Hamacher, Christina; Gross, Birgit; Sparbier, Katrin; Lange, Christoph; Kostrzewa, Markus; Schubert, Sören

    2016-11-01

    With the increasing prevalence of multidrug-resistant Gram-negative bacteria, rapid identification of the pathogen and its individual antibiotic resistance is crucial to ensure adequate antiinfective treatment at the earliest time point. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry for the identification of bacteria directly from the blood culture bottle has been widely established; however, there is still an urgent need for new methods that permit rapid resistance testing. Recently, a semiquantitative MALDI-TOF mass spectrometry-based method for the prediction of antibiotic resistance was described. We evaluated this method for detecting nonsusceptibility against two β-lactam and two non-β-lactam antibiotics. A collection of 30 spiked blood cultures was tested for nonsusceptibility against gentamicin and ciprofloxacin. Furthermore, 99 patient-derived blood cultures were tested for nonsusceptibility against cefotaxime, piperacillin-tazobactam, and ciprofloxacin in parallel with MALDI-TOF mass spectrometry identification from the blood culture fluid. The assay correctly classified all isolates tested for nonsusceptibility against gentamicin and cefotaxime. One misclassification for ciprofloxacin nonsusceptibility and five misclassifications for piperacillin-tazobactam nonsusceptibility occurred. Identification of the bacterium and prediction of nonsusceptibility was possible within approximately 4 h.

  2. A validated positive chemical ionization GC/MS method for the identification and quantification of amphetamine, opiates, cocaine, and metabolites in human postmortem brain.

    PubMed

    Lowe, Ross H; Barnes, Allan J; Lehrmann, Elin; Freed, William J; Kleinman, Joel E; Hyde, Thomas M; Herman, Mary M; Huestis, Marilyn A

    2006-02-01

    A sensitive and specific method for the simultaneous detection and quantification of amphetamine, opiates, and cocaine and metabolites in human postmortem brain was developed and validated. Analytes of interest included amphetamine, morphine, codeine, 6-acetylmorphine, cocaine, benzoylecgonine, ecgonine methyl ester, ecgonine ethyl ester, cocaethylene, and anhydroecgonine methyl ester. The method employed ultrasonic homogenization of brain tissue in pH 4.0 sodium acetate buffer and solid phase extraction. Extracts were derivatized with N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide and N,O-bis(trimethylsilyl) trifluoroacetamide. Separation and quantification were accomplished on a bench-top positive chemical ionization capillary gas chromatograph/mass spectrometer with selected ion monitoring. Eight deuterated analogs were used as internal standards. Limits of quantification were 50 ng/g of brain. Calibration curves were linear to 1000 ng/g for anhydroecgonine methyl ester and 6-acetylmorphine, and to 2000 ng/g for all other analytes. Accuracy across the linear range of the assay ranged from 90.2 to 112.2%, and precision, as percent relative standard deviation, was less than 16.6%. Quantification of drug concentrations in brain is a useful research tool in neurobiology and in forensic and postmortem toxicology, identifying the type, relative magnitude, and recency of abused drug exposure. This method will be employed to quantify drug concentrations in human postmortem brain in support of basic and clinical research on the physiologic, biochemical, and behavioral effects of drugs in humans.

  3. Liquid chromatography-electrospray ionization tandem mass spectrometry and dynamic multiple reaction monitoring method for determining multiple pesticide residues in tomato.

    PubMed

    Andrade, G C R M; Monteiro, S H; Francisco, J G; Figueiredo, L A; Botelho, R G; Tornisielo, V L

    2015-05-15

    A quick and sensitive liquid chromatography-electrospray ionization tandem mass spectrometry method, using dynamic multiple reaction monitoring and a 1.8-μm particle size analytical column, was developed to determine 57 pesticides in tomato in a 13-min run. QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for samples preparations and validations was carried out in compliance with EU SANCO guidelines. The method was applied to 58 tomato samples. More than 84% of the compounds investigated showed limits of detection equal to or lower than 5 mg kg(-1). A mild (<20%), medium (20-50%), and strong (>50%) matrix effect was observed for 72%, 25%, and 3% of the pesticides studied, respectively. Eighty-one percent of the pesticides showed recoveries ranging between 70% and 120%. Twelve pesticides were detected in 35 samples, all below the maximum residue levels permitted in the Brazilian legislation; 15 samples exceeded the maximum residue levels established by the EU legislation for methamidophos; and 10 exceeded limits for acephate and four for bromuconazole.

  4. Liquid chromatography-particle beam electron ionization mass spectrometry method for analysis of botanical extracts: evaluation of ephedrine alkaloids in standard reference materials.

    PubMed

    Castro, Joaudimir; Krishna, M V Balarama; Marcus, R Kenneth

    2010-01-01

    The preliminary validation of a high-performance liquid chromatography particle beam mass spectrometry method (HPLC-PB/MS) with electron impact ionization source for analysis of botanical extracts is presented. The LC-PB/MS system was evaluated for the analysis of ephedrine alkaloids using ephedra-containing National Institute of Standards and Technology dietary supplement standard reference materials (SRMs) 3241 Ephedra Sinica Stapf Native Extract and 3242 Ephedra Sinica Stapf Commercial Extract. The ephedrine alkaloids were separated by reversed-phase chromatography using a phenyl column at room temperature. A linear gradient method with a mobile phase composition varying from 5:95 [MeOH:0.1% trifluoroacetic acid (TFA) in water] to 20:80 (MeOH:0.1% TFA in water) at a flow rate of 1.0 ml/min, with an analysis time of less than 20 min, was used. The source block temperature was evaluated to determine the optimal operating conditions by monitoring the intensities and fragmentation patterns of the ephedrine alkaloids. Ephedrine and N-methylephedrine were taken as a representative of the test alkaloids. The LODs on the sub-nanogram level were achieved, with ephedrine, pseudoephedrine, and methylephedrine in the SRMs quantified by a standard addition method with recoveries of > or = 86% and RSDs of < or = 14% (n = 3).

  5. A positive chemical ionization GC/MS method for the determination of airborne ethylene glycol and propylene glycols in non-occupational environments.

    PubMed

    Zhu, Jiping; Feng, Yong-Lai; Aikawa, Bio

    2004-11-01

    An analytical method for ethylene glycol and propylene glycols has been developed for measuring airborne levels of these chemicals in non-occupational environments such as residences and office buildings. The analytes were collected on charcoal tubes, solvent extracted, and analyzed by gas chromatography-mass spectrometry using a positive chemical ionization technique. The method had a method detection limit of 0.07 microg m(-3) for ethylene glycol and 0.03 microg m(-3) for 1,2- and 1,3-propylene glycols, respectively, based on a 1.44 m3 sampling volume. Indoor air samples of several residential homes and other indoor environments have been analyzed. The median concentrations of ethylene glycol and 1,2-propylene glycol in nine residential indoor air samples were 53 microg m(-3) and 13 microg m(-3) respectively with maximum values of 223 microg m(-3) and 25 microg m(-3) detected for ethylene glycol and 1,2-propylene glycol respectively. The concentrations of these two chemicals in one office and two laboratories were at low microg m(-3) levels. The maximum concentration of 1,3-propylene glycol detected in indoor air was 0.1 microg m(-3).

  6. Comparison of Vitek Matrix-assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Versus Conventional Methods in Candida Identification.

    PubMed

    Keçeli, Sema Aşkın; Dündar, Devrim; Tamer, Gülden Sönmez

    2016-02-01

    Candida species are generally identified by conventional methods such as germ tube or morphological appearance on corn meal agar, biochemical methods using API kits and molecular biological methods. Alternative to these methods, rapid and accurate identification methods of microorganisms called matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDİ-TOF MS) has recently been described. In this study, Candida identification results by API Candida kit, API 20C AUX kit and identifications on corn meal agar (CMA) are compared with the results obtained on Vitek-MS. All results were confirmed by sequencing internal transcribed spacer (ITS) regions of rDNA. Totally, 97 Candida strains were identified by germ tube test, CMA, API and Vitek-MS. Vitek-MS results were compatible with 74.2 % of API 20C AUX and 81.4 % of CMA results. The difference between the results of API Candida and API 20C AUX was detected. The ratio of discrepancy between Vitek-MS and API 20C AUX was 25.8 %. Candida species mostly identified as C. famata or C. tropicalis by and not compatible with API kits were identified as C. albicans by Vitek-MS. Sixteen Candida species having discrepant results with Vitek-MS, API or CMA were randomly chosen, and ITS sequence analysis was performed. The results of sequencing were compatible 56.2 % with API 20C AUX, 50 % with CMA and 93.7 % with Vitek-MS. When compared with conventional identification methods, MS results are more reliable and rapid for Candida identification. MS system may be used as routine identification method in clinical microbiology laboratories.

  7. Correction factors for the NMi free-air ionization chamber for medium-energy x-rays calculated with the Monte Carlo method.

    PubMed

    Grimbergen, T W; van Dijk, E; de Vries, W

    1998-11-01

    A new method is described for the determination of x-ray quality dependent correction factors for free-air ionization chambers. The method is based on weighting correction factors for mono-energetic photons, which are calculated using the Monte Carlo method, with measured air kerma spectra. With this method, correction factors for electron loss, scatter inside the chamber and transmission through the diaphragm and front wall have been calculated for the NMi free-air chamber for medium-energy x-rays for a wide range of x-ray qualities in use at NMi. The newly obtained correction factors were compared with the values in use at present, which are based on interpolation of experimental data for a specific set of x-ray qualities. For x-ray qualities which are similar to this specific set, the agreement between the correction factors determined with the new method and those based on the experimental data is better than 0.1%, except for heavily filtered x-rays generated at 250 kV. For x-ray qualities dissimilar to the specific set, differences up to 0.4% exist, which can be explained by uncertainties in the interpolation procedure of the experimental data. Since the new method does not depend on experimental data for a specific set of x-ray qualities, the new method allows for a more flexible use of the free-air chamber as a primary standard for air kerma for any x-ray quality in the medium-energy x-ray range.

  8. Measurement of the top quark mass in the dilepton final state using the matrix element method

    SciTech Connect

    Grohsjean, Alexander

    2008-12-15

    The top quark, discovered in 1995 by the CDF and D0 experiments at the Fermilab Tevatron Collider, is the heaviest known fundamental particle. The precise knowledge of its mass yields important constraints on the mass of the yet-unobserved Higgs boson and allows to probe for physics beyond the Standard Model. The first measurement of the top quark mass in the dilepton channel with the Matrix Element method at the D0 experiment is presented. After a short description of the experimental environment and the reconstruction chain from hits in the detector to physical objects, a detailed review of the Matrix Element method is given. The Matrix Element method is based on the likelihood to observe a given event under the assumption of the quantity to be measured, e.g. the mass of the top quark. The method has undergone significant modifications and improvements compared to previous measurements in the lepton+jets channel: the two undetected neutrinos require a new reconstruction scheme for the four-momenta of the final state particles, the small event sample demands the modeling of additional jets in the signal likelihood, and a new likelihood is designed to account for the main source of background containing tauonic Z decay. The Matrix Element method is validated on Monte Carlo simulated events at the generator level. For the measurement, calibration curves are derived from events that are run through the full D0 detector simulation. The analysis makes use of the Run II data set recorded between April 2002 and May 2008 corresponding to an integrated luminosity of 2.8 fb-1. A total of 107 t$\\bar{t}$ candidate events with one electron and one muon in the final state are selected. Applying the Matrix Element method to this data set, the top quark mass is measured to be mtopRun IIa = 170.6 ± 6.1(stat.)-1.5+2.1(syst.)GeV; mtopRun IIb = 174.1 ± 4.4(stat.)-1.8+2.5(syst.)GeV; m

  9. Identifying strategies to assist final semester nursing students to develop numeracy skills: a mixed methods study.

    PubMed

    Ramjan, Lucie M; Stewart, Lyn; Salamonson, Yenna; Morris, Maureen M; Armstrong, Lyn; Sanchez, Paula; Flannery, Liz

    2014-03-01

    It remains a grave concern that many nursing students within tertiary institutions continue to experience difficulties with achieving medication calculation competency. In addition, universities have a moral responsibility to prepare proficient clinicians for graduate practice. This requires risk management strategies to reduce adverse medication errors post registration. To identify strategies and potential predictors that may assist nurse academics to tailor their drug calculation teaching and assessment methods. This project builds on previous experience and explores students' perceptions of newly implemented interventions designed to increase confidence and competence in medication calculation. This mixed method study surveyed students (n=405) enrolled in their final semester of study at a large, metropolitan university in Sydney, Australia. Tailored, contextualised interventions included online practice quizzes, simulated medication calculation scenarios developed for clinical practice classes, contextualised 'pen and paper' tests, visually enhanced didactic remediation and 'hands-on' contextualised workshops. Surveys were administered to students to determine their perceptions of interventions and to identify whether these interventions assisted with calculation competence. Test scores were analysed using SPSS v. 20 for correlations between students' perceptions and actual performance. Qualitative open-ended survey questions were analysed manually and thematically. The study reinforced that nursing students preferred a 'hands-on,' contextualised approach to learning that was 'authentic' and aligned with clinical practice. Our interventions assisted with supporting students' learning and improvement of calculation confidence. Qualitative data provided further insight into students' awareness of their calculation errors and preferred learning styles. Some of the strongest predictors for numeracy skill performance included (1) being an international student, (2

  10. Development of an analytical method for detecting nitrofurans in bee pollen by liquid chromatography-electrospray ionization tandem mass spectrometry.

    PubMed

    Park, Mi Sun; Kim, Kyung Tae; Kang, Jong Seong

    2017-03-01

    Bee pollen collected by honeybees, which is in powdered form, is a good nutritional supplement. Nitrofuran antibiotics are assumed not to be present in bee pollen, which is important as the level of antibiotics in bee pollen is strongly regulated in many countries. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to detect nitrofurans in honey has been developed, but this method is not suitable for bee pollen because of it being in powdered form. During preparation of bee pollen samples, the dispersal of powder particles in an aqueous solution often makes them susceptible to forming an emulsion with solvent components such as hexane and ethyl acetate. This may reduce the reproducibility and sensitivity of analyses of nitrofuran levels in bee pollen. Therefore, we attempted to optimize the sample preparation conditions to detect nitrofurans in bee pollen by determining three nitrofuran residues, namely, 3-amino-2-oxazolidinone (AOZ), 3-amino-5-methyl-morpholino-2-oxazolidinone (AMOZ), and 1-aminohydantoin (AHD), using LC-MS/MS. The optimized method prevented the formation of powder-induced emulsion. To verify the reproducibility and sensitivity of this method, it was validated using nitrofuran-free bee pollen spiked with analytes with different side chains at 1.0, 2.0, and 5.0μgkg(-1). The accuracy levels were 94.1%-104.0% and the coefficients of variation were less than 12%. The limits of detection for AOZ, AMOZ, and AHD were 0.18, 0.25, and 0.30μgkg(-1), respectively, while their limits of quantitation were 0.59, 0.83, and 1.00μgkg(-1). The LC-MS/MS method developed to analyze nitrofuran in bee pollen should contribute to the quality control of bee pollen and food safety. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Contrast Enhanced Ultrasound - A Novel Non-Invasive Non-Ionizing Method for the Detection of Brown Adipose Tissue in Humans

    PubMed Central

    Flynn, A.; Li, Q.; Panagia, M.; Abdelbaky, A.; MacNabb, M.; Samir, A.; Cypess, AM.; Weyman, AE.; Tawakol, A.; Scherrer-Crosbie, M.

    2015-01-01

    Background Brown adipose tissue (BAT) consumes glucose when it is activated by cold exposure, allowing its detection in humans by 18-F fluorodeoxyglucose positron emission tomography with computed tomography (18F-FDG PET-CT). We recently described a novel non-invasive and non-ionizing imaging method to assess BAT in mice using contrast enhanced ultrasound (CEUS). Here, we report the application of this method in healthy humans. Methods Thirteen healthy volunteers were recruited. CEUS was performed before and after cold exposure in all subjects using a continuous intravenous infusion of perflutren gas filled lipid microbubbles and triggered imaging of the supraclavicular space. The first 5 subjects received microbubbles at a lower infusion rate than the subsequent 8 subjects, and are analyzed as a separate group. Blood flow was estimated by the product of the plateau (A) and the slope (β) of microbubble replenishment curves. All underwent 18F-FDG PET-CT after cold exposure. Results An increase in the acoustic signal was noted in the supraclavicular adipose tissue area with increasing triggering intervals in all subjects, demonstrating the presence of blood flow. The area imaged by CEUS co-localized with BAT, as detected by 18F-FDG PET-CT. In a cohort of 8 subjects with an optimized CEUS protocol, CEUS-derived BAT blood flow increased with cold exposure compared to basal BAT blood flow in warm conditions (Aβ 3.3 [0.5–5.7] AU/s vs. 1.25 [0.5–2.6] AU/s; p=0.02). Of these 8 subjects, 5 had a >2-fold increase in their blood flow after cold exposure; these responders had higher BAT activity measured by 18F-FDG PET-CT (SUVmax 2.25 [1.53–4.57] vs. 0.51 [0.47–0.73]; p=0.02). Conclusions The present study demonstrates the feasibility of using CEUS as a non-invasive, non-ionizing imaging modality in estimating BAT blood flow in young, healthy humans. CEUS may be a useful and scalable tool in the assessment of BAT and BAT-targeted therapies. PMID:26255029

  12. Ionization potentials of seaborgium

    SciTech Connect

    Johnson, E.; Pershina, V.; Fricke, B.

    1999-10-21

    Multiconfiguration relativistic Dirac-Fock values were calculated for the first six ionization potentials of seaborgium and of the other group 6 elements. No experimental ionization potentials are available for seaborgium. Accurate experimental values are not available for all of the other ionization potentials. Ionic radii for the 4+ through 6+ ions of seaborgium are also presented. The ionization potentials and ionic radii obtained will be used to predict some physiochemical properties of seaborgium and its compounds.

  13. An ultrahigh-performance liquid chromatography method with electrospray ionization tandem mass spectrometry for simultaneous quantification of five phytohormones in medicinal plant Glycyrrhiza uralensis under abscisic acid stress.

    PubMed

    Xiang, Yu; Song, Xiaona; Qiao, Jing; Zang, Yimei; Li, Yanpeng; Liu, Yong; Liu, Chunsheng

    2015-07-01

    An efficient simplified method was developed to determine multiple classes of phytohormones simultaneously in the medicinal plant Glycyrrhiza uralensis. Ultrahigh-performance liquid chromatography electrospray ionization tandem mass spectrometry (UPLC/ESI-MS/MS) with multiple reaction monitoring (MRM) in negative mode was used for quantification. The five studied phytohormones are gibberellic acid (GA3), abscisic acid (ABA), jasmonic acid (JA), indole-3-acetic acid, and salicylic acid (SA). Only 100 mg of fresh leaves was needed, with one purification step based on C18 solid-phase extraction. Cinnamic acid was chosen as the internal standard instead of isotope-labeled internal standards. Under the optimized conditions, the five phytohormones with internal standard were separated within 4 min, with good linearities and high sensitivity. The validated method was applied to monitor the spatial and temporal changes of the five phytohormones in G. uralensis under ABA stress. The levels of GA3, ABA, JA, and SA in leaves of G. uralensis were increased at different times and with different tendencies in the reported stress mode. These changes in phytohormone levels are discussed in the context of a possible feedback regulation mechanism. Understanding this mechanism will provide a good chance of revealing the mutual interplay between different biosynthetic routes, which could further help elucidate the mechanisms of effective composition accumulation in medicinal plants.

  14. High-performance liquid chromatography-ultraviolet-visible spectroscopy-electrospray ionization mass spectrometry method for acrylic and polyester forensic fiber dye analysis.

    PubMed

    Petrick, Lauren M; Wilson, Trevor A; Ronald Fawcett, W

    2006-07-01

    A critical point of comparison between a fiber collected from a crime scene and a fiber from a known source is the color. Fiber dye analysis using thin-layer chromatography or ultraviolet (UV)-visible (Vis) microspectrophotometry provides useful, although limited, data for comparison. High-performance liquid chromatography-electrospray ionization mass spectrometry (LC/MS) overcomes these limitations by integrating chromatography, ultraviolet-visible spectroscopy, and mass spectrometry into a single instrument. In order to evaluate the applicability of the LC/MS to forensic fiber dye analysis, a multi-stage chromatographic method using acidified water and acidified acetonitrile was developed that separated and identified a mixture of 15 basic and 13 disperse dye standards. The LC/MS also detected and analyzed dyes extracted from individual 0.5 cm acrylic and polyester fibers, demonstrating its applicability to this type of analysis. With regard to the analysis of disperse dyes in polyester fibers, the replacement of pyridine with acetonitrile in the extraction system allowed direct injection of the extracts into the LC/MS. The advantage of the LC/MS over other instrumental methods of textile dye analysis is demonstrated by the analysis and differentiation of three black acrylic fibers: two fibers had similar UV-Vis spectra but were differentiated with chromatography and two had similar UV-Vis spectra and chromatograms but were differentiated using the mass spectrometer.

  15. Simple and sensitive method for pyrroloquinoline quinone (PQQ) analysis in various foods using liquid chromatography/electrospray-ionization tandem mass spectrometry.

    PubMed

    Noji, Natsumi; Nakamura, Takemichi; Kitahata, Nobutaka; Taguchi, Katsuhiko; Kudo, Toshiaki; Yoshida, Shigeo; Tsujimoto, Masafumi; Sugiyama, Tamizi; Asami, Tadao

    2007-09-05

    Pyrroloquinoline quinone (PQQ) is believed to be an important factor for mammalian growth and development and has, therefore, been declared a vitamin by some researchers. However, this issue remains controversial, and from a nutritional viewpoint, accurate determination of PQQ levels in a variety of foods is very important. Here, we describe a simple, highly sensitive, and highly selective method for quantitative analysis of PQQ. Liquid foods or aqueous extracts of solid foods were analyzed using high-performance liquid chromatography (HPLC) combined with electrospray-ionization (ESI) tandem mass spectrometry (MS/MS). (15)N-labeled PQQ was added to the samples as an internal standard. Quantitative analyses of PQQ were performed by multiple reaction monitoring (MRM) with LC/MS/MS. Free PQQ was detected in almost all food samples in the range 0.19-7.02 ng per g fresh weight (for solid foods) or per mL (liquid foods). This method will enable the rapid and simple determination of PQQ levels in many samples.

  16. A method for quantitating the intracellular metabolism of AZT amino acid phosphoramidate pronucleotides by capillary high-performance liquid chromatography-electrospray ionization mass spectrometry.

    PubMed

    Kim, Jisook; Park, Soobong; Tretyakova, Natalia Y; Wagner, Carston R

    2005-01-01

    A methodology has been developed for the analysis of the intracellular metabolism of 3'-azido-3'-deoxythymidine (AZT) amino acid phosphoramidates utilizing reverse-phase high-performance liquid chromatography interfaced with negative ion electrospray ionization mass spectrometry (LC/ESI(-) -MS). The presented work demonstrates the potential of capillary LC/MS and LC/MS/MS to identify and quantitate the cellular uptake and metabolism of nucleoside phosphoramidate. Significant intracellular amounts of D- and L-phenylalanine methyl ester or D- and L-tryptophan methyl ester AZT phosphoramidates were observed for human T-lymphoblastoid leukemia (CEM) cells incubated for 2 and 4 h with the prodrugs. AZT-MP was the primary metabolite observed for human T-lymphoblastoid leukemia (CEM) cells. In this paper, the details of using LC/MS to analyze AZT amino acid phosphoramidates in biological samples are discussed. LC/MS is an efficient method for analyzing multiple samples containing several analytes in a short period of time. The method also provides high selectivity and sensitivity, and requires minimal sample preparation. This approach should be broadly applicable for the analysis of the intracellular metabolism of nucleoside prodrugs and pronucleotides.

  17. Ionization Cooling using Parametric Resonances

    SciTech Connect

    Johnson, Rolland P.

    2008-06-07

    Ionization Cooling using Parametric Resonances was an SBIR project begun in July 2004 and ended in January 2008 with Muons, Inc., (Dr. Rolland Johnson, PI), and Thomas Jefferson National Accelerator Facility (JLab) (Dr. Yaroslav Derbenev, Subcontract PI). The project was to develop the theory and simulations of Parametric-resonance Ionization Cooling (PIC) so that it could be used to provide the extra transverse cooling needed for muon colliders in order to relax the requirements on the proton driver, reduce the site boundary radiation, and provide a better environment for experiments. During the course of the project, the theoretical understanding of PIC was developed and a final exposition is ready for publication. Workshops were sponsored by Muons, Inc. in May and September of 2007 that were devoted to the PIC technique. One outcome of the workshops was the interesting and somewhat unexpected realization that the beam emittances using the PIC technique can get small enough that space charge forces can be important. A parallel effort to develop our G4beamline simulation program to include space charge effects was initiated to address this problem. A method of compensating for chromatic aberrations by employing synchrotron motion was developed and simulated. A method of compensating for spherical aberrations using beamline symmetry was also developed and simulated. Different optics designs have been developed using the OptiM program in preparation for applying our G4beamline simulation program, which contains all the power of the Geant4 toolkit. However, no PIC channel design that has been developed has had the desired cooling performance when subjected to the complete G4beamline simulation program. This is believed to be the consequence of the difficulties of correcting the aberrations associated with the naturally large beam angles and beam sizes of the PIC method that are exacerbated by the fringe fields of the rather complicated channel designs that have been

  18. Improved methods for water shutoff. Final technical progress report, October 1, 1997--September 30, 1998

    SciTech Connect

    Seright, R.S.; Liang, J.T.; Schrader, R.; Hagstrom, J. II; Liu, J.; Wavrik, K.

    1998-10-01

    In the United States, more than 20 billion barrels of salt water are produced each year during oilfield operations. A tremendous economic incentive exists to reduce water production if that can be accomplished without significantly sacrificing hydrocarbon production. This three-year research project had three objectives. The first objective was to identify chemical blocking agents that will (a) during placement, flow readily through fractures without penetrating significantly into porous rock and with screening out or developing excessive pressure gradients and (b) at a predictable and controllable time, become immobile and resistant breakdown upon exposure to moderate to high pressure gradients. The second objective was to identify schemes that optimize placement of the above blocking agents. The third objective was to explain why gels and other chemical blocking agents reduce permeability to one phase (e.g., water) more than that to another phase (e.g., oil or gas). The authors also wanted to identify conditions that maximize this phenomenon. This project consisted of three tasks, each of which addressed one of the above objectives. This report describes work performed during the third and final period of the project. During this three-year project, they: (1) Developed a procedure and software for sizing gelant treatments in hydraulically fractured production wells; (2) Developed a method (based on interwell tracer results) to determine the potential for applying gel treatments in naturally fractured reservoirs; (3) Characterized gel properties during extrusion through fractures; (4) Developed a method to predict gel placement in naturally fractured reservoirs; (5) Made progress in elucidating the mechanism for why some gels can reduce permeability to water more than that to oil; (6) Demonstrated the limitations of using water/oil ratio diagnostic plots to distinguish between channeling and coning; and (7) Proposed a philosophy for diagnosing and attacking water

  19. Ionization Energies of Lanthanides

    ERIC Educational Resources Information Center

    Lang, Peter F.; Smith, Barry C.

    2010-01-01

    This article describes how data are used to analyze the pattern of ionization energies of the lanthanide elements. Different observed pathways of ionization between different ground states are discussed, and the effects of pairing, exchange, and orbital interactions on ionization energies of the lanthanides are evaluated. When all the above…

  20. Ionization Energies of Lanthanides

    ERIC Educational Resources Information Center

    Lang, Peter F.; Smith, Barry C.

    2010-01-01

    This article describes how data are used to analyze the pattern of ionization energies of the lanthanide elements. Different observed pathways of ionization between different ground states are discussed, and the effects of pairing, exchange, and orbital interactions on ionization energies of the lanthanides are evaluated. When all the above…

  1. Atmospheric sampling glow discharge ionization source

    DOEpatents

    McLuckey, S.A.; Glish, G.L.

    1989-07-18

    An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above. 3 figs.

  2. Atmospheric sampling glow discharge ionization source

    DOEpatents

    McLuckey, Scott A.; Glish, Gary L.

    1989-01-01

    An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above.

  3. A sensitive method for digoxin determination using formate-adduct ion based on the effect of ionization enhancement in liquid chromatograph-mass spectrometer.

    PubMed

    Li, Xia; Wang, Yu; Zhou, Qingyuan; Yu, Yunqiu; Chen, Lihong; Zheng, Jie

    2015-01-26

    A sensitive and rapid method based on formate-adduct ion detection was developed and fully validated for digoxin determination in rat plasma. For LC/MS/MS detection with formate-adducts as precursor ions, transitions of m/z 825.5→779.9 for digoxin and m/z 809.5→763.4 for the internal standard (digitoxin) were monitored in negative mode. To investigate the impact of formic acid on the mass response and method sensitivity, a formic acid concentration range of 0-0.1% (0, 0.0005%, 0.002%, 0.01%, 0.1%, v/v) was evaluated. A concentration of 0.002% gave the highest sensitivity, which was 16- to 18-fold higher than deprotonated ions, and was designated as the contribution giving the strongest ionization enhancement and adduction. A number of parameters were then varied in order to optimize the method, and a limit of quantitation (LOQ) at 0.2 ng/mL was reached with an injection volume of 5 μL, a total run time of 3 min, and 0.1 mL of rat plasma. A calibration curve was plotted over the range 0.2-50 ng/mL (R(2)=0.9998), and the method was successfully applied to study pharmacokinetics in rat following a single oral administration of digoxin (0.05 mg/kg). Four additional steroid saponins (digitoxin, deslanoside, ginsenoside Rg1 and Rb1) were investigated to assess the impact of formic acid on the mass response of steroid saponins. Compounds with a conjugated lactonic ring in their structures such as digoxin, digitoxin and deslanoside tended to form stable formate-adduct ions more easily. The LC/MS/MS method developed here is therefore well suited for the quantification of steroid saponins that are difficult to deprotonate using other MS approaches.

  4. A Nanoparticle-based Solid Phase Extraction Method for Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometric Analysis

    PubMed Central

    Song, Yaru; Zhao, Shulin; Tchounwou, Paul; Liu, Yi-Ming

    2007-01-01

    A solid-phase extraction (SPE) procedure with the use of superparamagnetic Fe3O4 nanoparticles as extracting agent was developed for HPLC-ESI-MS/MS analysis. Four most heavily used triazine pesticides (herbicides) were taken as the test compounds. The NPs showed an excellent capability to retain the compounds tested, and a quantitative extraction was achieved within 10 min under the testing conditions, i.e. 100 μL NP solution was added to 400 mL sample in a beaker with stirring. After extraction, the superparamagnetic NPs were easily collected by using an external magnet. Very importantly, analytes retained on the Fe3O4 NPs could be quantitatively recovered by dissolving the NPs with an HCl solution, allowing subsequent HPLC-ESI-MS/MS quantification. A capillary HPLC-ESI-MS/MS method with the present NP-based SPE procedure was developed for the determination of triazines including atrazine, prometryn, terbutryn, and propazine. Atrazine-d5 was used as internal standard. The method had an LOD of 10 pg/mL atrazine, and a linear calibration curve over a range from 30 pg – 50.0 ng/mL. Simultaneous determination of the four triazine pesticides in water samples taken from local lakes was demonstrated. PMID:17723235

  5. A novel derivatization method for the determination of Fosfomycin in human plasma by liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometric detection via phase transfer catalyzed derivatization.

    PubMed

    Papakondyli, Theodora A; Gremilogianni, Aikaterini M; Megoulas, Nikolaos C; Koupparis, Michael A

    2014-03-07

    An analytical method employing novel sample preparation and liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometric detection (LC-APCI/MS) was developed for the determination of fosfomycin in human plasma. Sample preparation involves derivatization through phase transfer catalysis (PTC) which offers multiple advantages due to the simultaneous extraction, preconcentration and derivatization of the analyte. Using a PT catalyst, fosfomycin was extracted from plasma in an organic phase and, then converted to a pentafluorobenzyl ester with the use of pentafluorobenzyl bromide (PFBBr) derivatization reagent. The method was fully optimized by taking into account both PTC and derivatization parameters. Several catalysts, in a wide range of concentrations, with different counter ions and polarities were tested along with different extraction solvents and pH values. Thereafter, the derivatization procedure was optimized by altering the amount of the derivatization reagent, the temperature of the reaction and finally, the derivatization duration. As internal standard (I.S.) ethylphosphonic acid was chosen and underwent the same pretreatment. The derivatives were separated on a pentafluorophenyl (PFP)-C18 analytical column, which provides unique selectivity, using an isocratic elution with acetonitrile-water (70-30, v/v). The method was validated according to US Food and Drug Administration (FDA) guidelines and can be used for a bioequivalence study of fosfomycin in human plasma. The correlation coefficient (r(2)) of the calibration curve of spiked plasma solutions in the range of 50-12000 ng/mL was found greater than 0.999 with a limit of quantitation (LOQ) equal to 50 ng/ml (for 500 μL plasma sample). Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Epicyclic Twin-Helix Ionization Cooling Simulations

    SciTech Connect

    Vasiliy Morozov, Yaroslav Derbenev, A. Afanaciev, R.P. Johnson

    2011-04-01

    Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a highluminosity muon collider. For the implementation of PIC, we earlier developed an epicyclic twin-helix channel with correlated behavior of the horizontal and vertical betatron motions and dispersion. We now insert absorber plates with short energy-recovering units located next to them at the appropriate locations in the twin-helix channel. We first demonstrate conventional ionization cooling in such a system with the optics uncorrelated. We then adjust the correlated optics state and induce a parametric resonance to study ionization cooling under the resonant condition.

  7. OVERVIEW OF A NEW EPA METHOD: DETERMINATION OF PERCHLORATE IN DRINKING WATER, GROUNDWATER AND HIGH SALINITY WATER BY ION CHROMATOGRAPHY, SUPPRESSED CONDUCTIVITY WITH ELECTROSPRAY IONIZATION MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    In this presentation the analytical instrumentation and procedures necessary to qualitatively and quantitatively determine low levels of perchlorate (ClO4-) in drinking waters using ion chromatography with electrolytic conductivity suppression, electrospray ionization mass spec...

  8. OVERVIEW OF A NEW EPA METHOD: DETERMINATION OF PERCHLORATE IN DRINKING WATER, GROUNDWATER AND HIGH SALINITY WATER BY ION CHROMATOGRAPHY, SUPPRESSED CONDUCTIVITY WITH ELECTROSPRAY IONIZATION MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    In this presentation the analytical instrumentation and procedures necessary to qualitatively and quantitatively determine low levels of perchlorate (ClO4-) in drinking waters using ion chromatography with electrolytic conductivity suppression, electrospray ionization mass spec...

  9. Ab Initio Study of Ionized Water Radical Cation (H2O)8(+) in Combination with the Particle Swarm Optimization Method.

    PubMed

    Tang, Mei; Hu, Cui-E; Lv, Zhen-Long; Chen, Xiang-Rong; Cai, Ling-Cang

    2016-12-01

    The structures of cationic water clusters (H2O)8(+) have been globally explored by the particle swarm optimization method in combination with quantum chemical calculations. Geometry optimization and vibrational analysis for the 15 most interesting clusters were computed at the MP2/aug-cc-pVDZ level and infrared spectrum calculation at MPW1K/6-311++G** level. Special attention was paid to the relationships between their configurations and energies. Both MP2 and B3LYP-D3 calculations revealed that the cage-like structure is the most stable, which is different from a five-membered ring lowest energy structure but agrees well with a cage-like structure in the literature. Furthermore, our obtained cage-like structure is more stable by 0.87 and 1.23 kcal/mol than the previously reported structures at MP2 and B3LYP-D3 levels, respectively. Interestingly, on the basis of their relative Gibbs free energies and the temperature dependence of populations, the cage-like structure predominates only at very low temperatures, and the most dominating species transforms into a newfound four-membered ring structure from 100 to 400 K, which can contribute greatly to the experimental infrared spectrum. By topological analysis and reduced density gradient analysis, we also investigated the structural characteristics and bonding strengths of these water cluster radical cations.

  10. Alignment- and orientation-dependent strong-field ionization of molecules: Field-induced orbital distortion effects

    NASA Astrophysics Data System (ADS)

    Spiewanowski, Maciej Dominik; Madsen, Lars Bojer

    2015-05-01

    Strong-field ionization (SFI) is a starting point for many strong-field phenomena, e.g., high-order harmonic generation, as well as a source of fundamental information about the ionized target. Therefore, investigation of SFI of atoms and molecules has been the aim for research since the first strong laser pulses became available. We present a recently developed method, adiabatic strong-field approximation, to study ionization yields as a function of alignment angle for CO2, CO, and OCS molecules. We show that orbital distortion plays an important role in explaining the position and relative strength of maxima in the yields for both polar and nonpolar molecules, even for targets with low polarizabilities at low laser intensities. In particular, we report that for ionization of CO2 the maximum in ionization yield shifts towards the experimentally-measured maximum with respect to the strong-field approximation. For ionization of the CO molecule, not only does the theory predict the preferred direction of ionization correctly, but also the ratio between yields for the two molecular orientations where the electric field points either towards the C or towards the O end. Finally, we find that ionization of OCS is more probable for the laser pointing from the O end towards the S end. Work supported by the Natural Sciences and Engineering Research Council of Canada, the ERC-StG (Project No. 277767-TDMET), and the VKR center of excellence, QUS- COPE.

  11. DETECTORS AND EXPERIMENTAL METHODS: Design and construction of the first prototype ionization chamber for CSNS and PA beam loss monitor (BLM) system

    NASA Astrophysics Data System (ADS)

    Xu, Mei-Hang; Tian, Jian-Min; Chen, Chang; Chen, Yuan-Bo; Xu, Tao-Guang; Lu, Shuang-Tong

    2009-02-01

    Design and construction of the first prototype ionization chamber for CSNS and Proton Accelerator (PA) beam loss monitor (BLM) system is reported. The low leakage current (<0.1 pA), good plateau (approx800 V) and linearity range up to 200 Roentgen/h are obtained in the first prototype. All of these give us good experience for further improving the ionization chamber construction.

  12. Forensic applications of ambient ionization mass spectrometry.

    PubMed

    Ifa, Demian R; Jackson, Ayanna U; Paglia, Giuseppe; Cooks, R Graham

    2009-08-01

    This review highlights and critically assesses forensic applications in the developing field of ambient ionization mass spectrometry. Ambient ionization methods permit the ionization of samples outside the mass spectrometer in the ordinary atmosphere, with minimal sample preparation. Several ambient ionization methods have been created since 2004 and they utilize different mechanisms to create ions for mass-spectrometric analysis. Forensic applications of these techniques--to the analysis of toxic industrial compounds, chemical warfare agents, illicit drugs and formulations, explosives, foodstuff, inks, fingerprints, and skin--are reviewed. The minimal sample pretreatment needed is illustrated with examples of analysis from complex matrices (e.g., food) on various substrates (e.g., paper). The low limits of detection achieved by most of the ambient ionization methods for compounds of forensic interest readily offer qualitative confirmation of chemical identity; in some cases quantitative data are also available. The forensic applications of ambient ionization methods are a growing research field and there are still many types of applications which remain to be explored, particularly those involving on-site analysis. Aspects of ambient ionization currently undergoing rapid development include molecular imaging and increased detection specificity through simultaneous chemical reaction and ionization by addition of appropriate chemical reagents.

  13. WE-E-BRE-11: New Method to Simulate DNA Damage Using Ionization Cross-Sections and a Geometrical Nucleosome Model

    SciTech Connect

    Pater, P; Seuntjens, J; El Naqa, I

    2014-06-15

    Purpose: To obtain probability distributions of various DNA damage types as a function of the incident electron kinetic energy. Methods: Using Geant4-DNA electron ionization cross-sections, we calculated path length distributions for electrons of energies between 10 eV and 1 MeV, defined as the length between two subsequent interactions. These path lengths were then convolved with probability distributions for the creation of same-strand damage, opposite-strand damage, clustered damage, isolated damage, and same DNA strand target damage. These probability distributions of DNA damage were obtained by a Monte Carlo routine calculating probabilities of interaction in DNA targets inside a nucleosome geometrical model. Results represent the probability of a secondary electron, initially created inside a DNA strand target, of undergoing its next interaction: (1) in the opposite strand (DSB), (2) in the same strand (SSB+), (3) in either the opposite or same-strand (clustered), (4) in the same DNA target (multiple-hit) or (5) more than 10 base pairs away (isolated). Results: Electrons with kinetic energy between 50 and 250 eV have a maximal probability of creating DSB, SSB+, clustered damage and multiple-hits in the same target The probabilities for these damage patterns have values of 2.5%, 4.3%, 6.7% and 5.4%, respectively. Isolated damage is most probable between 700 eV to 900 eV with a probability of 0.2%. Conclusion: We obtained DNA damage probability distributions as a function of electron incident energy. We showed that electrons with kinetic energies between 50 and 250 eV have the highest probability of producing complex forms of DNA damage (DSB, SSB+). We also showed that a double ionization within the same DNA target is the most frequent outcome occurring 5% of the time. It is expected that electron slowing down spectra can be convolved with our formalism to calculate source specific DNA damage patterns. Research grants from governments of Canada and Quebec. PP

  14. A novel high-performance liquid chromatography-electron spray ionization-mass spectrometry method for simultaneous determination of guggulsterones, piperine and gallic acid in Triphala guggulu

    PubMed Central

    Muguli, Ganesh; Vadaparthi, P. R. Rao; Ramesh, B.; Gowda, Vishakante; Paramesh, Rangesh; Jadhav, Atul N.; Babu, K. Suresh

    2015-01-01

    “Triphalaguggulu” is an important Ayurvedic formulation comprising of Guggulu, that is, Commiphora wightii (Arn.) Bhandari as a base wherein powdered fruits of triphala, that is, Phyllanthus emblica L., Terminalia bellirica (Gaertn.) Roxb and Terminalia chebula Retz, along with powdered fruit of Piper longum L. are compounded. This polyherbal preparation has been strongly recommended in chronic inflammation, piles, and fistula. However, due to the complexity of compound formulation standardization of commercial products is challenging. In the present communication marker-based standardization of “Triphalaguggulu” preparation using gallic acid (for triphala), piperine (for P. longum L.) and guggulsterones (for guggulu) is reported. These compounds of diverse chemistry were successfully separated on a Waters HR-C18 column by isocratic elution with methanol and water (80:20 v/v) as mobile phase at the flow rate of 1.0 mL/min coupled with photodiode array detector. These optimal chromatographic conditions were used for simultaneous quantification of gallic acid, guggulsterones (E and Z) and piperine in commercial samples by high-performance liquid chromatography-electron spray ionization-mass spectrometry and method was validated as per ICH guidelines. PMID:26109777

  15. Development of an SPE method for the determination of zaleplon and zopiclone in hemolyzed blood using fast GC with negative-ion chemical ionization MS.

    PubMed

    Karlonas, Nerijus; Ramanavicius, Arunas; Ramanaviciene, Almira

    2014-03-01

    An SPE procedure for the determination of zaleplon and zopiclone in low-volume human hemolyzed blood using fast GC with negative-ion chemical ionization MS has been developed and validated. Both analytes were well retained on Oasis MCX and HLB columns, and sufficient extraction efficiency was achieved at pH 9.0. For further study a hydrophilic-lipophilic sorbent Oasis HLB was selected due to the polarity of sorbent surface and its large surface area in order to achieve efficient extraction of both analytes in a single step. Special attention has been paid to choosing washing and eluting solvents, resulting in a particularly/extremely clean and moisture-free extract. The mean extraction efficiency was higher than 90.1% for zaleplon and 82.9% for zopiclone. The precision for zaleplon and zopiclone was between 3.04-10.58% and 4.08-9.52%, respectively. Whereas the accuracy was in the range from -5.73 to 6.00%, and from -7.00 to 6.32% for zaleplon and zopiclone, respectively. The results show that the developed method is accurate, selective, precise, and very fast with excellent recovery and low LOD and LOQ.

  16. NERI PROJECT 99-119. TASK 1. ADVANCED CONTROL TOOLS AND METHODS. FINAL REPORT

    SciTech Connect

    March-Leuba, J.A.

    2002-09-09

    Nuclear plants of the 21st century will employ higher levels of automation and fault tolerance to increase availability, reduce accident risk, and lower operating costs. Key developments in control algorithms, fault diagnostics, fault tolerance, and communication in a distributed system are needed to implement the fully automated plant. Equally challenging will be integrating developments in separate information and control fields into a cohesive system, which collectively achieves the overall goals of improved performance, safety, reliability, maintainability, and cost-effectiveness. Under the Nuclear Energy Research Initiative (NERI), the U. S. Department of Energy is sponsoring a project to address some of the technical issues involved in meeting the long-range goal of 21st century reactor control systems. This project, ''A New Paradigm for Automated Development Of Highly Reliable Control Architectures For Future Nuclear Plants,'' involves researchers from Oak Ridge National Laboratory, University of Tennessee, and North Carolina State University. This paper documents a research effort to develop methods for automated generation of control systems that can be traced directly to the design requirements. Our final goal is to allow the designer to specify only high-level requirements and stress factors that the control system must survive (e.g. a list of transients, or a requirement to withstand a single failure.) To this end, the ''control engine'' automatically selects and validates control algorithms and parameters that are optimized to the current state of the plant, and that have been tested under the prescribed stress factors. The control engine then automatically generates the control software from validated algorithms. Examples of stress factors that the control system must ''survive'' are: transient events (e.g., set-point changes, or expected occurrences such a load rejection,) and postulated component failures. These stress factors are specified by the

  17. Development, optimization, validation and application of faster gas chromatography - flame ionization detector method for the analysis of total petroleum hydrocarbons in contaminated soils.

    PubMed

    Zubair, Abdulrazaq; Pappoe, Michael; James, Lesley A; Hawboldt, Kelly

    2015-12-18

    This paper presents an important new approach to improving the timeliness of Total Petroleum Hydrocarbon (TPH) analysis in the soil by Gas Chromatography - Flame Ionization Detector (GC-FID) using the CCME Canada-Wide Standard reference method. The Canada-Wide Standard (CWS) method is used for the analysis of petroleum hydrocarbon compounds across Canada. However, inter-laboratory application of this method for the analysis of TPH in the soil has often shown considerable variability in the results. This could be due, in part, to the different gas chromatography (GC) conditions, other steps involved in the method, as well as the soil properties. In addition, there are differences in the interpretation of the GC results, which impacts the determination of the effectiveness of remediation at hydrocarbon-contaminated sites. In this work, multivariate experimental design approach was used to develop and validate the analytical method for a faster quantitative analysis of TPH in (contaminated) soil. A fractional factorial design (fFD) was used to screen six factors to identify the most significant factors impacting the analysis. These factors included: injection volume (μL), injection temperature (°C), oven program (°C/min), detector temperature (°C), carrier gas flow rate (mL/min) and solvent ratio (v/v hexane/dichloromethane). The most important factors (carrier gas flow rate and oven program) were then optimized using a central composite response surface design. Robustness testing and validation of model compares favourably with the experimental results with percentage difference of 2.78% for the analysis time. This research successfully reduced the method's standard analytical time from 20 to 8min with all the carbon fractions eluting. The method was successfully applied for fast TPH analysis of Bunker C oil contaminated soil. A reduced analytical time would offer many benefits including an improved laboratory reporting times, and overall improved clean up

  18. The strong-field ionization mechanisms of molecules and clusters

    NASA Astrophysics Data System (ADS)

    Sayres, Scott Grayson

    to be in agreement with other techniques. Moreover, the appearance potentials of the fragments have been measured and are also in relatively good agreement with literature results, as well as calculated adiabatic values. In Chapter 5, an in depth investigation to the ionization mechanism of ammonia is detailed and compared to the mechanism observed in ammonia clusters. Ionization is observed to originate from multiple orbitals, with the orbital contributions separated by m/z in the mass spectrometer. Upon clustering, complete removal of all valence electrons was observed orders of magnitude lower in laser intensity than expected. This extreme ionization enhancement demonstrates tunneling from all valence orbitals. Ionization occurs non-sequentially indicating that once an orbital is accessed by the laser, it is emptied of electrons. Chapter 6 discusses the measurement of the ionization potentials of small silicon clusters. The intensity scan method can be used to determine the ionization potential of stable clusters and even be used as a new technique for discovering magic clusters. The high charge states are found to behave according to as if their ionization potentials were lowered by ~40%. They also demonstrate a nonsequential ionization mechanism. Chapter 7 discusses the ionization mechanisms for the Group Vb transition metal (V, Nb, and Ta) oxide clusters. The exchange of the metal ion does not lead to extensive changes in the energy requirements of the high charge states. However, the more stable the cluster distribution, the further the ionization proceeds. The appearance of the high charge states of the oxygen are not only enhanced, but demonstrate disagreement with the expected appearance ordering from the ADK model. The ionization mechanism is attributed to arising from frozen orbitals. As many orbitals are similar in energy, this leads to a steady flowing of electrons from the clusters at low laser intensities, before significant movement occurs. Finally

  19. Infrared laser-assisted desorption electrospray ionization mass spectrometry.

    PubMed

    Rezenom, Yohannes H; Dong, Jianan; Murray, Kermit K

    2008-02-01

    We have used an infrared laser for desorption of material and ionization by interaction with electrosprayed solvent. Infrared laser-assisted desorption electrospray ionization (IR LADESI) mass spectrometry was used for the direct analysis of water-containing samples under ambient conditions. An ion trap mass spectrometer was modified to include a pulsed Er:YAG laser at 2.94 microm wavelength coupled into a germanium oxide optical fiber for desorption at atmospheric pressure and a nanoelectrospray source for ionization. Analytes in aqueous solution were placed on a stainless steel target and irradiated with the pulsed IR laser. Material desorbed and ablated from the target was ionized by a continuous stream of charged droplets from the electrosprayed solvent. Peptide and protein samples analyzed using this method yield mass spectra similar to those obtained by conventional electrospray. Blood and urine were analyzed without sample pretreatment to demonstrate the capability of IR LADESI for direct analysis of biological fluids. Pharmaceutical products were also directly analyzed. Finally, the role of water as a matrix in the IR LADESI process is discussed.

  20. Ionization states in the microenvironment of solid dosage forms: effect of formulation variables and processing.

    PubMed

    Govindarajan, Ramprakash; Zinchuk, Andrey; Hancock, Bruno; Shalaev, Evgenyi; Suryanarayanan, Raj

    2006-10-01

    Evaluation of the effect of formulation composition and processing variables on the microenvironment in solid dosage forms, based on ionization of indicator probes. Sulfonephthalein indicators were intimately mixed with individual excipients, binary excipient mixtures or multi-component blends by the solvent deposition method. Diffuse reflectance visible spectroscopy of these solids provided a measure of indicator ionization extent. Indicator solution studies yielded equations relating solution pH to the ratio of the absorbance signals of the ionized to that of the unionized form, for each indicator. These equations and the spectral data of the indicator-treated solids were used to calculate an acidity function, 'pH(eq)' for the solids. The ionization of incorporated probes was also monitored during various stages of simulated pharmaceutical processing viz. wet and dry mixing. The pH(eq) provided a measure of the physicochemical environment experienced by the probe in the solid. The surface nature of formulation components and their surface area available for interaction influenced the overall properties of the final blend. The extent of probe ionization varied at different stages of a simulated wet mixing-drying process. The pH of the excipient suspension was not a good predictor of the probe ionization in the final dried solid. Indicator ionization is expected to be influenced by the microenvironmental acidity, polarity and ionic strength. Individual excipient properties contributed to the overall microenvironment in powder mixtures even when dry mixed at low water contents. The environment experienced by a drug in the final solid dosage form will be influenced by the nature of the excipients, the extent of their surfaces available for interaction, surface modification during processing and the amount and nature of solvent used.

  1. Development and validation of a liquid chromatography/electrospray ionization time-of-flight mass spectrometry method for relative and absolute quantification of steroidal alkaloids in Fritillaria species.

    PubMed

    Zhou, Jian-Liang; Li, Ping; Li, Hui-Jun; Jiang, Yan; Ren, Mei-Ting; Liu, Ying

    2008-01-04

    Steroidal alkaloids are naturally occurring nitrogen-containing compounds in many edible or medicinal plants, such as potato, tomato, Fritillaria and American hellebore, which possess a variety of toxicological and pharmacological effects on humans. The aim of this study is to explore the potential of liquid chromatography/electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOF-MS) method in the determination of these important alkaloids in plant matrices. The application of this method has been proven through 26 naturally occurring steroidal alkaloids in Fritillaria species. Accurate mass measurements within 4 ppm error were obtained for all the alkaloids detected out of various plant matrices, which allowed an unequivocal identification of the target steroidal alkaloids. The bunching factor for mass spectrometer, an important parameter significantly affecting the precision and accuracy of quantitative method, was firstly optimized in this work and satisfactory precision and linearity were achieved by the optimization of that parameter. The ranges of RSD values of intra-day and inter-day variability for all alkaloids were decreased remarkably from 41.8-159% and 13.2-140% to 0.32-7.98% and 2.37-16.1%, respectively, when the value of bunching factor was optimized from 1 to 3. Linearity of response more than two orders of magnitude was also demonstrated (regression coefficient >0.99). The LC/TOF-MS detection method offered improvements to the sensitivity, compared with previously applied LC (or GC) methods, with limits of detection down to 0.0014-0.0335 microg/ml. The results in this paper illustrate the robustness and applicability of LC/TOF-MS for steroidal alkaloids analysis in plant samples. In addition, relative quantitative determination of steroidal alkaloid with one popular analyte verticinone which is commercially available was also investigated in order to break through the choke point of lack of standards in phytochemical analysis. The

  2. Validation of a qualitative screening method for pesticides in fruits and vegetables by gas chromatography quadrupole-time of flight mass spectrometry with atmospheric pressure chemical ionization.

    PubMed

    Portolés, T; Mol, J G J; Sancho, J V; López, Francisco J; Hernández, F

    2014-08-01

    A wide-scope screening method was developed for the detection of pesticides in fruit and vegetables. The method was based on gas chromatography coupled to a hybrid quadrupole time-of-flight mass spectrometer with an atmospheric pressure chemical ionization source (GC-(APCI)QTOF MS). A non-target acquisition was performed through two alternating scan events: one at low collision energy and another at a higher collision energy ramp (MS(E)). In this way, both protonated molecule and/or molecular ion together with fragment ions were obtained in a single run. Validation was performed according to SANCO/12571/2013 by analysing 20 samples (10 different commodities in duplicate), fortified with a test set of 132 pesticides at 0.01, 0.05 and 0.20mg kg(-1). For screening, the detection was based on one diagnostic ion (in most cases the protonated molecule). Overall, at the 0.01mg kg(-1) level, 89% of the 2620 fortifications made were detected. The screening detection limit for individual pesticides was 0.01mg kg(-1) for 77% of the pesticides investigated. The possibilities for identification according to the SANCO criteria, requiring two ions with a mass accuracy ≤±5ppm and an ion-ratio deviation ≤±30%, were investigated. At the 0.01mg kg(-1) level, identification was possible for 70% of the pesticides detected during screening. This increased to 87% and 93% at the 0.05 and 0.20mg kg(-1) level, respectively. Insufficient sensitivity for the second ion was the main reason for the inability to identify detected pesticides, followed by deviations in mass accuracy and ion ratios. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Hydrophilic interaction liquid chromatography/positive ion electrospray ionization mass spectrometry method for the quantification of alprazolam and α-hydroxy-alprazolam in human plasma.

    PubMed

    Kalogria, Eleni; Pistos, Constantinos; Panderi, Irene

    2013-12-30

    A hydrophilic interaction liquid chromatography/positive ion electrospray-mass spectrometry (HILIC-ESI/MS) has been developed and fully validated for the quantification of alprazolam and its main metabolite, α-hydroxy-alprazolam, in human plasma. The assay is based on 50μL plasma samples, following liquid-liquid extraction. All analytes and the internal standard (tiamulin) were separated by hydrophilic interaction liquid chromatography using an X-Bridge-HILIC analytical column (150.0mm×2.1mm i.d., particle size 3.5μm) under isoscratic elution. The mobile phase was composed of a 7% 10mM ammonium formate water solution in acetonitrile and pumped at a flow rate of 0.20mLmin(-1). Running in positive electrospray ionization and selected ion monitoring (SIM) the mass spectrometer was set to analyze the protonated molecules [M+H](+) at m/z 309, 325 and 494 for alprazolam, α-hydroxy-alprazolam and tiamulin (ISTD) respectively. The assay was linear over the concentration range of 2.5-250ngmL(-1) for alprazolam and 2.5-50ngmL(-1) for α-hydroxy alprazolam. Intermediate precision was less than 4.1% over the tested concentration ranges. The method is the first reported application of HILIC in the analysis benzodiazepines in human plasma. With a small sample size (50μL human plasma) and a run time less than 10.0min for each sample the method can be used to support a wide range of clinical studies concerning alprazolam quantification.

  4. Dynamics of multiple ionization of atoms and molecules by electron, photon, and ion impact—investigated by the COLTRIMS imaging method

    NASA Astrophysics Data System (ADS)

    Schmidt-Böcking, H.; Schmidt, L.; Weber, Th.; Mergel, V.; Jagutzki, O.; Czasch, A.; Hagmann, S.; Doerner, R.; Demkov, Y.; Jahnke, T.; Prior, M.; Cocke, C. L.; Osipov, T.; Landers, A.

    2004-10-01

    Fully differential cross-sections in momentum space for multiple ionization processes of atoms and molecules have been investigated by a multi-coincidence imaging technique, called COLTRIMS (cold target recoil ion momentum spectroscopy) (J. Phys. B 30 (1997) 2917; Nucl. Instrum. Methods B 108 (1996) 425; In: Ullrich, J., Shevelko, V.P. (Eds.), Many Particle Quantum Dynamics in Atomic Fragmentation, Series Atomic, Optical, and Plasma Physics, Vol. 35. Springer, Berlin, 2003; Phys. Rep. 330 (2000) 95). This technique is as powerful as the bubble chamber system in high-energy physics. It has opened a new observation window into the hidden world of many-particle dynamics: correlated many-particle dynamics in Coulombic systems can now be experimentally approached with unprecedented completeness and precision. The principle of the method, namely measuring the momentum of the emitted charged particles from an atomic or molecular fragmentation process, is as simple as determining the trajectory of a thrown stone. From knowing the position from where the stone was slung and where it hits the target, as well as measuring its time-of-flight, the trajectory of the stone and thus its initial velocity vector can be determined precisely. Furthermore, in order to achieve good precision we have to know whether the person, who throws the stone, was at rest in the frame of observation or with which relative velocity this person was moving. Thus, to obtain optimal momentum resolution for the exploding fragments one has to bring the fragmenting object to a complete rest in the frame of measurement before the reaction occurs, i.e. if the object is a gas atom or molecule one has to cool it down to sub-milli Kelvin temperatures.

  5. Clinical Performance of a Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Method for Detection of Certain blaKPC-Containing Plasmids.

    PubMed

    Youn, Jung-Ho; Drake, Steven K; Weingarten, Rebecca A; Frank, Karen M; Dekker, John P; Lau, Anna F

    2016-01-01

    Rapid detection of blaKPC-containing organisms can significantly impact infection control and clinical practices, as well as therapeutic choices. Current molecular and phenotypic methods to detect these organisms, however, require additional testing beyond routine organism identification. In this study, we evaluated the clinical performance of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to detect pKpQIL_p019 (p019)-an ∼11,109-Da protein associated with certain blaKPC-containing plasmids that was previously shown to successfully track a clonal outbreak of blaKPC-pKpQIL-Klebsiella pneumoniae in a proof-of-principle study (A. F. Lau, H. Wang, R. A. Weingarten, S. K. Drake, A. F. Suffredini, M. K. Garfield, Y. Chen, M. Gucek, J. H. Youn, F. Stock, H. Tso, J. DeLeo, J. J. Cimino, K. M. Frank, and J. P. Dekker, J Clin Microbiol 52:2804-2812, 2014, http://dx.doi.org/10.1128/JCM.00694-14). PCR for the p019 gene was used as the reference method. Here, blind analysis of 140 characterized Enterobacteriaceae isolates using two protein extraction methods (plate extraction and tube extraction) and two peak detection methods (manual and automated) showed sensitivities and specificities ranging from 96% to 100% and from 95% to 100%, respectively (2,520 spectra analyzed). Feasible laboratory implementation methods (plate extraction and automated analysis) demonstrated 96% sensitivity and 99% specificity. All p019-positive isolates (n = 26) contained blaKPC and were carbapenem resistant. Retrospective analysis of an additional 720 clinical Enterobacteriaceae spectra found an ∼11,109-Da signal in nine spectra (1.3%), including seven from p019-containing, carbapenem-resistant isolates (positive predictive value [PPV], 78%). Instrument tuning had a significant effect on assay sensitivity, highlighting important factors that must be considered as MALDI-TOF MS moves into applications beyond microbial identification. Using a large blind

  6. Systematic Process Synthesis and Design Methods for Cost Effective Waste Minimization. Final report

    SciTech Connect

    Biegler, L.T.; Grossmann, I.E.; Westerberg, A.W.

    1998-02-14

    This report focuses on research done over the past four years under the grant with the above title. In addition, the report also includes a brief summary of work done before 1994 under grant DOE-DE-FG02-85ER13396. Finally, a complete list of publications that acknowledge support from this grant is listed at the end.

  7. Charge exchange ionization in collision cells as a method to detect the presence of long-lived excited electronic states of polyatomic ions.

    PubMed

    Kwon, C H; Kim, M S; Choe, J C

    2001-10-01

    Charge exchange ionization in collision cells installed in a double focusing mass spectrometer with reversed geometry has been used to detect the presence of a long-lived excited electronic state of benzene ion. In particular, the first collision cell located between the ion source and the magnetic sector was modified to serve as an ion source for the reagent ion generated by charge exchange with the primary ion. Strong reagent ion signals were observed when the ionization energies of the reagents (1,3-C4H6, CS2, CH3Cl) were lower than the recombination energy (approximately 11.5 eV) of the excited state benzene ion, while the signals were negligible for reagents (CH3F,CH4) with higher ionization energy. The fact that a strong signal is observable only for electronically exoergic charge exchange is useful for detecting the presence of a long-lived electronically excited state.

  8. Evolution of N/O abundance ratios and ionization parameters from z ˜ 0 to 2 investigated by the direct temperature method*†

    NASA Astrophysics Data System (ADS)

    Kojima, Takashi; Ouchi, Masami; Nakajima, Kimihiko; Shibuya, Takatoshi; Harikane, Yuichi; Ono, Yoshiaki

    2017-06-01

    We present N/O abundance ratios, ionization parameters qion, and oxygen abundances O/H for a total of 41 galaxies (11 individual galaxies and a 30-galaxy stack) including Lyα emitters and Lyman break galaxies at z ∼ 2, and investigate galaxy evolution from z ∼ 0 to 2 in conjunction with 208529 local galaxies from the Sloan Digital Sky Survey (SDSS) and nine green pea galaxies (GPs). In contrast with most of the recent studies, we obtain the N/O ratio, qion, and O/H measurements by direct Te methods using [O III] λ4363 and O III] λ1665 lines. Based on these reliable measurements, we find that there are z ∼ 2 galaxies with excesses of N/O falling beyond the N/O-O/H relation of the local galaxies while the majority of the z ∼ 2 galaxies have N/O ratios that are nearly comparable with those of z ∼ 0 galaxies in the N/O-stellar mass relation. Our galaxies place the upper limit of the N/O ratio log(N/O) ≤ -1.26 on average, suggesting that the N/O ratio evolves, if at all, by <0.17 dex. Obtaining the reliable measurements free from the N/O-qion-O/H degeneracies, we demonstrate, for the first time, that z ∼ 2 galaxies with offsets in the Baldwin-Phillips-Terlevich (BPT) diagram show (1) only an N/O excess, (2) only a qion excess, or (3) both N/O and qion excesses. We argue that the BPT offsets at z ∼ 2 are not made by one of the (1)-(3) galaxy populations alone, but a composite of (1)-(3) populations. We confirm that these (1)-(3) populations also exist at z ∼ 0, such as GPs and SDSS low-mass and high-SFR galaxies (LMHSs).

  9. The development of a matrix-assisted laser desorption/ionization mass spectrometry-based method for the protein fingerprinting and identification of Aeromonas species using whole cells.

    PubMed

    Donohue, Maura J; Smallwood, Anthony W; Pfaller, Stacy; Rodgers, Mark; Shoemaker, Jody A

    2006-06-01

    This report describes the development of a method to detect the waterborne pathogen Aeromonas using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The genus Aeromonas is one of several medically significant genera that have gained prominence due to their evolving taxonomy and controversial role in human diseases. In this study, MALDI-MS was applied to the characterization of seventeen species of Aeromonas. These seventeen species were represented by thirty-two strains, which included type, reference and clinical isolates. Intact cells from each strain were used to generate a reproducible library of protein mass spectral fingerprints or m/z signatures. Under the test conditions used, peak lists of the mass ions observed in each species revealed that three mass ions were conserved among all the seventeen species tested. These common mass ions having an average m/z of 6301, 12,160 or 12,254, and 13,450, can be potentially used as genus-specific biomarkers to identify Aeromonas in unknown samples. A dendrogram generated using the m/z signatures of all the strains tested indicated that the mass spectral data contained sufficient information to distinguish between genera, species, and strains. There are several advantages of using MALDI-MS based protein mass spectral fingerprinting of whole cells for the identification of microorganisms as well as for their differentiation at the sub-species level: (1) the capability to detect proteins, (2) high throughput, and (3) relatively simple sample preparation techniques. The accuracy and speed with which data can be obtained makes MALDI-MS a powerful tool especially suited for environmental monitoring and detection of biological hazards.

  10. DOE-energy related inventions program: [Develop method to treat industrial powders]. Final report

    SciTech Connect

    Kemp, W.E.

    1998-05-13

    In a Mechanical Fluidized Vacuum machine a horizontally disposed retort is two-thirds filled with material and rotated at a speed that keeps the material in a fluidized state. The objective of this project was to build and demonstrate a machine to thermally treat up to 600 kg lots of metal and cermet powders to temperatures of 940C with low energy cost and environmental impact. Quantification tests of many powders were conducted, design machine modification was done to expand the basic machine, a retort was constructed and prepared, and performance trials were made on the final machine. Final tests were conducted on a retort measuring 22 inches in diameter and 30 inches long. Operating cost data are presented.

  11. Method for determining trace quantities of chloride in polymeric materials using ion selective electrodes: Final report

    SciTech Connect

    Salary, J.

    1987-02-01

    A method for determining trace quantities of chloride in polymeric materials has been developed. Ion-selective electrodes and the standard addition method were used in all the analyses. The ion-selective electrode method was compared with neutron activation, ion chromatography and chloridometer titration. The ion-selective electrode technique results for chloride were similar to those of neutron activation, which is the acknowledged referee method. This ion-selective electrode method showed the highest standard recovery when compared with the ion chromatography and chloridometer titration methods.

  12. Development of matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) for plant metabolite analysis

    SciTech Connect

    Korte, Andrew R

    2014-12-01

    This thesis presents efforts to improve the methodology of matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) as a method for analysis of metabolites from plant tissue samples. The first chapter consists of a general introduction to the technique of MALDI-MSI, and the sixth and final chapter provides a brief summary and an outlook on future work.

  13. Influence of the geometrical detail in the description of DNA and the scoring method of ionization clustering on nanodosimetric parameters of track structure: a Monte Carlo study using Geant4-DNA

    NASA Astrophysics Data System (ADS)

    Bueno, M.; Schulte, R.; Meylan, S.; Villagrasa, C.

    2015-11-01

    between m1 and the cumulative relative frequency of clusters with ν ≥slant 3 (f3) within statistical variations, independently of particle type. In order to obtain ionization cluster size distributions relevant for biological DNA lesions, the complex DNA geometry and a scoring method without fixed boundaries should be preferred to the simple cylindrical geometry with a fixed scoring volume.

  14. A multi-residue method for pesticides analysis in green coffee beans using gas chromatography-negative chemical ionization mass spectrometry in selective ion monitoring mode.

    PubMed

    Pizzutti, Ionara R; de Kok, Andre; Dickow Cardoso, Carmem; Reichert, Bárbara; de Kroon, Marijke; Wind, Wouter; Weber Righi, Laís; Caiel da Silva, Rosselei

    2012-08-17

    In this study, a new gas chromatography-mass spectrometry (GC-MS) method, using the very selective negative chemical ionization (NCI) mode, was developed and applied in combination with a modified acetonitrile-based extraction method (QuEChERS) for the analysis of a large number of pesticide residues (51 pesticides, including isomers and degradation products) in green coffee beans. A previously developed integrated sample homogenization and extraction method for both pesticides and mycotoxins analysis was used. An homogeneous slurry of green milled coffee beans and water (ratio 1:4, w/w) was prepared and extracted with acetonitrile/acetic acid (1%), followed by magnesium sulfate addition for phase separation. Aliquots from this extract could be used directly for LC-MS/MS analysis of mycotoxins and LC-amenable pesticides. For GC-MS analysis, a further clean-up was necessary. C18- and PSA-bonded silica were tested as dispersive solid-phase extraction (d-SPE) sorbents, separate and as a mixture, and the best results were obtained using C18-bonded silica. For the optimal sensitivity and selectivity, GC-MS detection in the NCI-selected ion monitoring (SIM) mode had to be used to allow the fast analysis of the difficult coffee bean matrix. The validation was performed by analyzing recovery samples at three different spike concentrations, 10, 20 and 50 μg kg(-1), with 6 replicates (n=6) at each concentration. Linearity (r(2)) of calibration curves, estimated instrument and method limits of detection and limits of quantification (LOD(i), LOD(m), LOQ(i) and LOQ(m), respectively), accuracy (as recovery %), precision (as RSD%) and matrix effects (%) were determined for each individual pesticide. From the 51 analytes (42 parent pesticides, 4 isomers and 5 degradation products) determined by GC-MS (NCI-SIM), approximately 76% showed average recoveries between 70-120% and 75% and RSD ≤ 20% at the lowest spike concentration of 10 μg kg(-1), the target method LOQ. For the

  15. The role of partial ionization effects in the chromosphere

    PubMed Central

    Martínez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo; Carlsson, Mats

    2015-01-01

    The energy for the coronal heating must be provided from the convection zone. However, the amount and the method by which this energy is transferred into the corona depend on the properties of the lower atmosphere and the corona itself. We review: (i) how the energy could be built in the lower solar atmosphere, (ii) how this energy is transferred through the solar atmosphere, and (iii) how the energy is finally dissipated in the chromosphere and/or corona. Any mechanism of energy transport has to deal with the various physical processes in the lower atmosphere. We will focus on a physical process that seems to be highly important in the chromosphere and not deeply studied until recently: the ion–neutral interaction effects in the chromosphere. We review the relevance and the role of the partial ionization in the chromosphere and show that this process actually impacts considerably the outer solar atmosphere. We include analysis of our 2.5D radiative magnetohydrodynamic simulations with the Bifrost code (Gudiksen et al. 2011 Astron. Astrophys. 531, A154 (doi:10.1051/0004-6361/201116520)) including the partial ionization effects on the chromosphere and corona and thermal conduction along magnetic field lines. The photosphere, chromosphere and transition region are partially ionized and the interaction between ionized particles and neutral particles has important consequences on the magneto-thermodynamics of these layers. The partial ionization effects are treated using generalized Ohm's law, i.e. we consider the Hall term and the ambipolar diffusion (Pedersen dissipation) in the induction equation. The interaction between the different species affects the modelled atmosphere as follows: (i) the ambipolar diffusion dissipates magnetic energy and increases the minimum temperature in the chromosphere and (ii) the upper chromosphere may get heated and expanded over a greater range of heights. These processes reveal appreciable differences between the modelled

  16. The role of partial ionization effects in the chromosphere.

    PubMed

    Martínez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo; Carlsson, Mats

    2015-05-28

    The energy for the coronal heating must be provided from the convection zone. However, the amount and the method by which this energy is transferred into the corona depend on the properties of the lower atmosphere and the corona itself. We review: (i) how the energy could be built in the lower solar atmosphere, (ii) how this energy is transferred through the solar atmosphere, and (iii) how the energy is finally dissipated in the chromosphere and/or corona. Any mechanism of energy transport has to deal with the various physical processes in the lower atmosphere. We will focus on a physical process that seems to be highly important in the chromosphere and not deeply studied until recently: the ion-neutral interaction effects in the chromosphere. We review the relevance and the role of the partial ionization in the chromosphere and show that this process actually impacts considerably the outer solar atmosphere. We include analysis of our 2.5D radiative magnetohydrodynamic simulations with the Bifrost code (Gudiksen et al. 2011 Astron. Astrophys. 531, A154 (doi:10.1051/0004-6361/201116520)) including the partial ionization effects on the chromosphere and corona and thermal conduction along magnetic field lines. The photosphere, chromosphere and transition region are partially ionized and the interaction between ionized particles and neutral particles has important consequences on the magneto-thermodynamics of these layers. The partial ionization effects are treated using generalized Ohm's law, i.e. we consider the Hall term and the ambipolar diffusion (Pedersen dissipation) in the induction equation. The interaction between the different species affects the modelled atmosphere as follows: (i) the ambipolar diffusion dissipates magnetic energy and increases the minimum temperature in the chromosphere and (ii) the upper chromosphere may get heated and expanded over a greater range of heights. These processes reveal appreciable differences between the modelled atmospheres

  17. Improved vehicle occupancy data collection methods. Final report, 1994--1997

    SciTech Connect

    Heidtman, K.; Skarpness, B.; Tornow, C.

    1997-12-31

    The report evaluates current and emerging vehicle occupancy data collection methodologies. Five primary methods for collecting vehicle occupancy data were identified: the traditional roadside/windshield observation method, a recently developed carousel observational method, photographic surveillance, mail-out or telephone surveys, and accident database extraction method. The findings show that other methods besides the traditional windshield method may be advantageous for collecting vehicle occupancy information. The key factors in selecting a collection method are the conditions under which vehicle occupancy is to be estimated. For example, the accident method and mail-out surveys are well suited for developing regional vehicle occupancy estimates, while the windshield method and carousel method are well suited for corridor-specific estimates. Another key finding, which impact the selection of a method and sampling period, is the fact that average vehicle occupancy estimates vary significantly by time-of-day, day-of-week, and month-of-year. The implications of this finding is that agencies cannot continue to infer yearly AVO estimates from data collected during a limited time period such as the morning rush hour period. Recommendations for selecting and implementing a vehicle occupancy data collection method are also provided.

  18. Comparison of three prospective analytical methods for benzene analysis in jet-fuel environments. Final report

    SciTech Connect

    Hossain, M.A.

    1990-08-01

    Accurate analysis of benzene in jet fuel has been a concern over the past several years. The method we have been using to analyze benzene in jet fuel is the NIOSH 1501 method, a method specifically designed for aromatic hydrocarbons including benzene. However, the method is not designed for analysis of benzene in jet fuel environments. At the present time there is no approved (either by NIOSH or OSHA) method for analysis of benzene in fuel environments. At the request of HQ AAC/SGPB, we recently conducted a study to compare three prospective analytical methods (NIOSH method 1501 (GC/FID wtih packed column) modified NIOSH 1501 method (GC/FID with capillary column), and High Pressure Liquid Chromatography with Ultraviolet Detection (HPLC/UV)). In this study spiked charcoal tube samples as well as air samples of known concentrations of benzene in JP-4 and Stoddard Solvents were analyzed by all three methods. The test results showed that modified NIOSH 1501 and HPLC methods had good correlation between spiked and measured amount of benzene in JP-4 and Stoddard Solvent mixtures. The NIOSH 1501 method utilizing packed column over estimated the test benzene concentration indicating positive interference from other hydrocarbons present in JP 4 and Stoddard Solvents.

  19. Advanced Thin Ionization Calorimeter (ATIC)

    NASA Technical Reports Server (NTRS)

    Wefel, John P.

    1998-01-01

    This is the final report for NASA grant NAGW-4577, "Advanced Thin Ionization Calorimeter (ATIC)". This grant covered a joint project between LSU and the University of Maryland for a Concept Study of a new type of fully active calorimeter to be used to measure the energy spectra of very high energy cosmic rays, particularly Hydrogen and Helium, to beyond 1014 eV. This very high energy region has been studied with emulsion chamber techniques, but never investigated with electronic calorimeters. Technology had advanced to the point that a fully active calorimeter based upon Bismuth Germanate (BGO) scintillating crystals appeared feasible for balloon flight (and eventually space) experiments.

  20. Unambiguous ionization amplitudes for electron-hydrogen scattering

    SciTech Connect

    Bartlett, P. L.; Bray, I.; Jones, S.; Stelbovics, A. T.; Kadyrov, A. S.; Bartschat, K.; Ver Steeg, G. L.; Scott, M. P.; Burke, P. G.

    2003-08-01

    According to quantum collision theory, scattering amplitudes are complex numbers, which are completely defined by their magnitude and phase. Although the phase information is generally not determined entirely in collision experiments, the phases are well defined and can be used to check computational models. We use four state-of-the-art approaches to calculate the magnitude and phase of the electron-hydrogen ionization amplitude in the Temkin-Poet S-wave model. We demonstrate that the correct phase can be extracted for each method by using the appropriate final-state continuum functions.

  1. Development of convective testing methods for low-rise multifamily buildings. Final report

    SciTech Connect

    Stiles, M.R.

    1996-08-01

    This report describes convective testing methods and protocols developed for use in weatherizing low-rise multifamily buildings. The methods can lead to controlling internal air movement and preventing leakage to the exterior by estimating magnitudes of air leakage pathways in garden and town house apartments. The 4 methods cited are: After-a-Retrofit; Equivalent Interfaces; Open-a-Door; and Add-a-Pathway. It is found that, because of modern interior finishing practices, convective problems tend to be more associated with indoor air quality than loss of space conditioning energy. The After-a-Retrofit method is the easiest to integrate into current diagnostic practices. In some cases, the Equivalent Interfaces method may be used on a production basis. The methods are an advance on current field practices that do not quantify the leakage pathways and research practices that require extensive equipment.

  2. Development of the residential case-specular epidemiologic investigation method. Final report

    SciTech Connect

    Zaffanella, L.E.; Savitz, D.A.

    1995-11-01

    The residential case-specular method is an innovative approach to epidemiologic studies of the association between wire codes and childhood cancer. This project was designed to further the development of the residential case-specular method, which seeks to help resolve the ``wire code paradox``. For years, wire codes have been used as surrogate measures of past electric and magnetic field (EMF) exposure. There is a magnetic field hypothesis that suggests childhood cancer is associated with exposure to magnetic fields, with wire codes as a proxy for these fields. The neighborhood hypothesis suggests that childhood cancer is associated with neighborhood characteristics and exposures other than magnetic fields, with wire codes as a proxy for these characteristics and exposures. The residential case-specular method was designed to discriminate between the magnetic field and the neighborhood hypothesis. Two methods were developed for determining the specular of a residence. These methods were tested with 400 randomly selected residences. The main advantage of the residential case-specular method is that it may efficiently confirm or eliminate the suspicion that control selection bias or confounding by neighborhood factors affected the results of case-control studies of childhood cancer and magnetic fields. The method may be applicable to both past and ongoing studies. The main disadvantage is that the method is untried. Consequently, further work is required to verify its validity and to ensure that sufficient statistical power can be obtained in a cost-effective manner.

  3. Integration of Research Studies: Meta-Analysis of Research. Methods of Integrative Analysis; Final Report.

    ERIC Educational Resources Information Center

    Glass, Gene V.; And Others

    Integrative analysis, or what is coming to be known as meta-analysis, is the integration of the findings of many empirical research studies of a topic. Meta-analysis differs from traditional narrative forms of research reviewing in that it is more quantitative and statistical. Thus, the methods of meta-analysis are merely statistical methods,…

  4. A final report on the extension of the MCSCF/CI method

    NASA Technical Reports Server (NTRS)

    Nelin, C. J.

    1984-01-01

    For the period of July 1982 through January 1983, the research carried out focused on the nature of metal adsorbate bonding. Two main areas were investigated in detail: (1) the adsorption of CO on Al, Na, Mg and Ni; and (2) bonding in transition metal oxides, CuO, CrO and MoO. These theoretical studies have lead to a new understanding of CO-metal bonding as well as to a better understanding of the d involvement in the bonding in transition metal oxides. Four areas associated with cluster model studies are discussed in detail: hybridization and changing in cluster model studies, the adsorption of CO on metals (Al, Na, Mg), the adsorption of CO on Ni, and finally the use of effective core potentials (ECP) in cluster models.

  5. A final report on the extension of the MCSCF/CI method

    NASA Technical Reports Server (NTRS)

    Nelin, C. J.

    1984-01-01

    For the period of July 1982 through January 1983, the research carried out focused on the nature of metal adsorbate bonding. Two main areas were investigated in detail: (1) the adsorption of CO on Al, Na, Mg and Ni; and (2) bonding in transition metal oxides, CuO, CrO and MoO. These theoretical studies have lead to a new understanding of CO-metal bonding as well as to a better understanding of the d involvement in the bonding in transition metal oxides. Four areas associated with cluster model studies are discussed in detail: hybridization and changing in cluster model studies, the adsorption of CO on metals (Al, Na, Mg), the adsorption of CO on Ni, and finally the use of effective core potentials (ECP) in cluster models.

  6. Geothermal reservoir assessment based on slim hole drilling. Volume 1, Analytical Method: Final report

    SciTech Connect

    Olson, H.J.

    1993-12-01

    The Hawaii Scientific Observation Hole (SOH) program was supplied by the State of Hawaii to drill six, 4,000 foot scientific observation holes on Maui and the Big Island of Hawaii to confirm and stimulate geothermal, resource development in Hawaii. After a lengthy permitting process, three SOHs, totaling 18,890 feet of mostly core drilling were finally drilled along the Kilauea East Rift Zone (KERZ) in the Puna district on the Big Island. The SOH program was highly successful in meeting the highly restrictive permitting conditions imposed on the program, and in developing slim hole drilling techniques, establishing subsurface geological conditions, and initiating an assessment and characterization of the geothermal resources potential of Hawaii - even though permitting specifically prohibited pumping or flowing the holes to obtain data of subsurface fluid conditions. The first hole, SOH-4, reached a depth of 2,000 meters, recorded a bottom hole temperature of 306.1 C, and established subsurface thermal continuity along the KERZ between the HGP-A and the True/Mid-Pacific Geothermal Venture wells. Although evidence of fossil reservoir conditions were encountered, no zones with obvious reservoir potential were found. The second hole SOH-1, was drilled to a depth of 1,684 meters, recorded a bottom hole temperature of 206.1 C, effectively doubled the size of the Hawaii Geothermal Project -- Abbott/Puna Geothermal Venture (HGP-A/PGV) proven/probable reservoir, and defined the northern limit of the HGP-A/PGV reservoir. The final hole, SOH-2, was drilled to a depth of 2,073 meters, recorded a bottom hole temperature of 350.5 C, and has sufficient indicated permeability to be designated as a potential ''discovery.''

  7. Biological Effects of Ionizing Radiation

    DOE R&D Accomplishments Database

    Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

    1952-04-07

    This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

  8. SRC-I demonstration plant analytical laboratory methods manual. Final technical report

    SciTech Connect

    Klusaritz, M.L.; Tewari, K.C.; Tiedge, W.F.; Skinner, R.W.; Znaimer, S.

    1983-03-01

    This manual is a compilation of analytical procedures required for operation of a Solvent-Refined Coal (SRC-I) demonstration or commercial plant. Each method reproduced in full includes a detailed procedure, a list of equipment and reagents, safety precautions, and, where possible, a precision statement. Procedures for the laboratory's environmental and industrial hygiene modules are not included. Required American Society for Testing and Materials (ASTM) methods are cited, and ICRC's suggested modifications to these methods for handling coal-derived products are provided.

  9. Advanced computational methods for nodal diffusion, Monte Carlo, and S{sub n} problems. Final Report

    SciTech Connect

    1994-12-31

    The work addresses basic computational difficulties that arise in the numerical simulation of neutral particle radiation transport: discretized radiation transport problems, iterative methods, selection of parameters, and extension of current algorithms.

  10. Final Rule: NESHAP for the Portland Cement Manufacturing Industry: Alternative Monitoring Method

    EPA Pesticide Factsheets

    EPA is extending its approval for the use of an alternative method to show compliance with hydrogen chloride (HCl) emissions limits in the National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry

  11. Charged-Particle Impact Ionization of Atoms

    SciTech Connect

    Bartschat, Klaus; Guan Xiaoxu

    2008-08-08

    We have developed a hybrid method to treat charged-particle impact ionization of complex atoms and ions. The essential idea is to describe the interaction between a fast projectile and the target perturbatively, up to second order, while the initial bound state and the ejected-electron--residual-ion interaction can be handled via a convergent R-matrix with pseudo-states (close-coupling) expansion. Example results for ionization of the heavy noble gases (Ne-Xe) by positron and electron impact are presented. The general scheme for a distorted-wave treatment of ionization by heavy-particle impact is described.

  12. Equation of motion coupled cluster methods for electron attachment and ionization potential in fullerenes C{sub 60} and C{sub 70}

    SciTech Connect

    Bhaskaran-Nair, Kiran; Kowalski, Karol; Moreno, Juana; Jarrell, Mark; Shelton, William A.

    2014-08-21

    In both molecular and periodic solid-state systems there is a need for the accurate determination of the ionization potential and the electron affinity for systems ranging from light harvesting polymers and photocatalytic compounds to semiconductors. The development of a Green's function approach based on the coupled cluster (CC) formalism would be a valuable tool for addressing many properties involving many-body interactions along with their associated correlation functions. As a first step in this direction, we have developed an accurate and parallel efficient approach based on the equation of motion-CC technique. To demonstrate the high degree of accuracy and numerical efficiency of our approach we calculate the ionization potential and electron affinity for C{sub 60} and C{sub 70}. Accurate predictions for these molecules are well beyond traditional molecular scale studies. We compare our results with experiments and both quantum Monte Carlo and GW calculations.

  13. Final Technical Report [Scalable methods for electronic excitations and optical responses of nanostructures: mathematics to algorithms to observables

    SciTech Connect

    Saad, Yousef

    2014-03-19

    The master project under which this work is funded had as its main objective to develop computational methods for modeling electronic excited-state and optical properties of various nanostructures. The specific goals of the computer science group were primarily to develop effective numerical algorithms in Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TDDFT). There were essentially four distinct stated objectives. The first objective was to study and develop effective numerical algorithms for solving large eigenvalue problems such as those that arise in Density Functional Theory (DFT) methods. The second objective was to explore so-called linear scaling methods or Methods that avoid diagonalization. The third was to develop effective approaches for Time-Dependent DFT (TDDFT). Our fourth and final objective was to examine effective solution strategies for other problems in electronic excitations, such as the GW/Bethe-Salpeter method, and quantum transport problems.

  14. Evaluation of hard-rock-cavern construction methods for compressed-air energy storage: Final report

    SciTech Connect

    Thrasher, J.E.; Lange, R.B.

    1988-04-01

    This report presents the results of construction cost and schedule estimates for caverns mined in hard rock for 100-MW and 220-MW compressed air energy storage (CAES) plants with 10 hours storage capacity and using either water-compensated cavern operation with constant turbine-inlet pressure operation on uncompensated cavern operation with sliding turbine-inlet pressure operation. The estimates are made for caverns mined by large-parallel-tunnel methods and by room-and-pillar methods. The results indicate that, for the cavern sizes involved, the room-and-pillar method is cost-competitive with the large-parallel-tunnel methods, but the method requires marginally more construction time. The largest cavern size in the estimates may, however, be approaching the size where the room-and-pillar method may no longer be competitive. The technical feasibility of water curtains for preventing or minimizing leakage of air from CAES hard-rock caverns is evaluated, and construction cost and schedule estimates are made for uncompensated caverns. It is concluded that the performance of water curtains is dependent upon the accuracy of the values of site specific variables and assumptions utilized in the design. A method is presented for assessing if a water curtain may be economical for a compensated CAES cavern. Such an assessment for a water curtain for an uncompensated CAES cavern is more complex and beyond the scope of this study. Also, a program for testing the operation of a water curtain in conjunction with an air-storage cavern operation is proposed. For the specific cavern sizes considered in this report, the estimated water-curtain construction costs and times for the uncompensated room-and-pillar caverns are found to be greater than for the uncompensated large-parallel-tunnel caverns. 11 refs., 18 figs., 19 tabs.

  15. A physical model for the acousto-ultrasonic method. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Kiernan, Michael T.; Duke, John C., Jr.

    1990-01-01

    A basic physical explanation, a model, and comments on NDE application of the acousto-ultrasonic (AU) method for composite materials are presented. The basis of this work is a set of experiments where a sending and a receiving piezoelectric transducer were both oriented normal to the surface, at different points, on aluminum plates, various composite plates, and a tapered aluminum plate. The purpose and basic idea is introduced. Also, general comments on the AU method are offered. A literature review is offered for areas pertinent, such as composite materials, wave propagation, ultrasonics, and the AU. Special emphasis is given to theory which is used later on and past experimental results that are important to the physical understanding of the AU method. The experimental set-up, procedure, and the ensuing analysis are described. The experimental results are presented in both a quantitative and qualitative manner. A physical understanding of experimental results based on elasticity solution is furnished. Modeling and applications of the AU method is discussed for composite material and general conclusions are stated. The physical model of the AU method for composite materials is offered, something which has been much needed and sorely lacking. This physical understanding is possible due to the extensive set of experimental measurements, also reported.

  16. Basic theory and methods of dosimetry for use in risk assessment of genotoxic chemicals. Final report

    SciTech Connect

    Ehrenberg, L.; Granath, F.

    1992-12-31

    This project is designed to be theoretical, with limited experimental input. The work then would have to be directed towards an identification of problems, with an emphasis on the potential ability of molecular/biochemical methods to reach a solution, rather than aiming at solutions of the problems. In addition, the work is dependent on experimental work within parallel projects. Initially, projects running at this laboratory were strongly tied up with practical matters, such as the development of monitoring methods for specific exposures, with limited resources for basic research. As sketched in the scientific report below, section 4 the meaningfulness of molecular/biochemical methods and their potential contribution to the problem of dsk estimation has to be seen against a broad overview of this problem and current efforts to solve it. This overview, given as a brief summary in section 3, shows the necessity of combining different fields of research, holding them together by strictly quantitative aspects.

  17. Development of low-energy methods for production of lime. Draft final report

    SciTech Connect

    Mallow, W.A.; Dziuk, J.J.; Daugherty, K.E.; Safa, A.

    1981-03-31

    Possible methods of reducing the fuel and energy requirements in the production of lime were identified. Four basic concepts were explored in pursuit of a viable method to improve the energy efficiency of lime manufacture: (1) enzymatic catalysis; (2) conversion by Lewis acids in protolytic solvents; (3) attrition grinding/frictional calcination; and (4) catalyzed calcination. The concept which proved most encouraging and which appears to be readily adaptable to current practice emerged with the discovery of the Fused Salt catalysts, which can be introduced with pulverized limestone in a furnace process similar to those commercially used today.

  18. Laboratory testing of geomembrane for waste containment EPA Method 9090, March 1995. Final report

    SciTech Connect

    Whitlock, R.W.

    1995-05-15

    This report describes the work performed by TRI/Environmental, Inc. (TRI) to determine the chemical compatibility of one geomembrane and one seamed geomembrane with four synthetically generated leachates. The objective was to determine the resistance of the geomembrane to changes caused by exposure to the leachates. Changes in physical and mechanical properties were measured after exposure to the leachates at 23 C and 50 C for 30, 60, 90 and 120 days. Exposures were performed in accordance with the exposure regimen specified in US Environmental Protection Agency (EPA) Method 9090A. Methods, results and discussion are provided. Test results are also provided in the Tables of Results which accompany this report.

  19. Final Report on Subcontract B605152. Multigrid Methods for Systems of PDEs

    SciTech Connect

    Brannick, James; Xu, Jinchao

    2015-07-07

    The project team has continued with work on developing aggressive coarsening techniques for AMG methods. Of particular interest is the idea to use aggressive coarsening with polynomial smoothing. Using local Fourier analysis the optimal values for the parameters involved in defining the polynomial smoothers are determined automatically in a way to achieve fast convergence of cycles with aggressive coarsening. Numerical tests have the sharpness of the theoretical results. The methods are highly parallelizable and efficient multigrid algorithms on structured and semistructured grids in two and three spatial dimensions.

  20. Fundamentals of ambient metastable-induced chemical ionization mass spectrometry and atmospheric pressure ion mobility spectrometry

    NASA Astrophysics Data System (ADS)

    Harris, Glenn A.

    Molecular ionization is owed much of its development from the early implementation of electron ionization (EI). Although dramatically increasing the library of compounds discovered, an inherent problem with EI was the low abundance of molecular ions detected due to high fragmentation leading to the difficult task of the correct chemical identification after mass spectrometry (MS). These problems stimulated the research into new ionization methods which sought to "soften" the ionization process. In the late 1980s the advancements of ionization techniques was thought to have reached its pinnacle with both electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). Both ionization techniques allowed for "soft" ionization of large molecular weight and/or labile compounds for intact characterization by MS. Albeit pervasive, neither ESI nor MALDI can be viewed as "magic bullet" ionization techniques. Both techniques require sample preparation which often included native sample destruction, and operation of these techniques took place in sealed enclosures and often, reduced pressure conditions. New open-air ionization techniques termed "ambient MS" enable direct analysis of samples of various physical states, sizes and shapes. One particular technique named Direct Analysis In Real Time (DART) has been steadily growing as one of the ambient tools of choice to ionize small molecular weight (< 1000 Da) molecules with a wide range of polarities. Although there is a large list of reported applications using DART as an ionization source, there have not been many studies investigating the fundamental properties of DART desorption and ionization mechanisms. The work presented in this thesis is aimed to provide in depth findings on the physicochemical phenomena during open-air DART desorption and ionization MS and current application developments. A review of recent ambient plasma-based desorption/ionization techniques for analytical MS is presented in

  1. Design Study of Methods for Sampling Migrant and Seasonal Farm Workers. Final Report.

    ERIC Educational Resources Information Center

    Kalsbeek, William D.; Parker, Rebecca Robin

    This report describes efforts to develop sampling methods to be used in national or regional studies of migrant and seasonal farm workers (MSFWs). Several facets of the MSFWs' lifestyle create sampling difficulties. One is mobility. Although the dynamic nature of MSFWs' movement is partly understood, it is sufficiently unpredictable to create…

  2. XFEM: Exploratory Research into the Extended Finite-Element Method, FY02 LDRD Final Report

    SciTech Connect

    MISH, K

    2003-02-26

    This report is one of two components, the first an overview document outlining the goals and results of the XFEM LDRD project, and the other (titled ''Structured Extended Finite Element Methods of Solids defined by Implicit Surfaces'') detailing the scientific advances developed under FY01/FY02 LDRD funding. The XFEM (Extended Finite-Element Method) Engineering LDRD/ER Project was motivated by three research and development goals: (1) the extensions of standard finite-element technology into important new research venues of interest to the Engineering Directorate, (2) the automation of much of the engineering analysis workflow, so as to improve the productivity of mesh-generation and problem setup processes, and (3) the development of scalable software tools to facilitate innovation in XFEM analysis and methods development. The driving principle behind this LDRD project was to demonstrate the computational technology required to perform mechanical analysis of complex solids, with minimal extra effort required on the part of mechanical analysts. This need arises both from the growing workload of LLNL analysts in problem setup and mesh generation, and from the requirement that actual as-built mechanical configurations be analyzed. Many of the most important programmatic drivers for mechanical analysis require that the actual (e.g., deformed, aged, damaged) geometric configuration of the solid be deduced and then accurately modeled: for this programmatic need, XFEM provides one of the only accurate methods available that can provide high-fidelity results.

  3. PROGRAMED INSTRUCTION AND THE DEMONSTRATION METHOD OF TEACHING AT THE JUNIOR HIGH LEVEL. FINAL REPORT.

    ERIC Educational Resources Information Center

    CLAWSON, BARBARA; SHOFFNER, SARAH M.

    A SELF-INSTRUCTIONAL PROGRAM ON SEWING WAS DEVELOPED AND COMPARED WITH THE TRADITIONAL LABORATORY-DEMONSTRATION METHOD OF TEACHING. THE PROGRAM COMPRISED SECTIONS ON SEWING MACHINES, PATTERNS, AND BLOUSE CONSTRUCTION, AND WAS INTENDED TO ACHIEVE PERFORMANCE OF LABORATORY TASKS, UNDERSTANDING OF THE PROCESSES INVOLVED, AND PREPARATION FOR TRANSFER…

  4. Study of improved methods for predicting chemical equilibria. Final report, January 1, 1990--March 31, 1993

    SciTech Connect

    Lenz, T.G.; Vaughan, J.D.

    1993-09-01

    Objective was to develop computational methods for equilibrium constants of Diels-Alder reactions in gas and liquid solution phases. Approach was to calculate standard enthalpies of formation at 298 K and standard thermodynamic functions for a range of temperatures for reactants and products, and then to calculate standard enthalpies, entropies, Gibbs free energies, and equilibrium constants at various temperatures.

  5. The Sight Method of Teaching Typewriting Technique and Keyboard. Final Report.

    ERIC Educational Resources Information Center

    Ruddle, Eleanor S.

    The purpose of the study was to test the hypothesis that students who watch their fingers in the beginning weeks of typewriting instruction will develop better techniques as shown on tests of speed and accuracy at the end of the school year than student who watch only their copy in accordance with the conventional teaching method. The major…

  6. Final Report: Advanced Methods for Accessing and Disseminating Nuclear Data, August 13, 1996 - March 15, 1999

    SciTech Connect

    Stone, Craig A.

    1999-03-15

    Scientific Digital Visions, Inc. developed methods of accessing and dissemination nuclear data contained within the databases of the National Data Center (NNDC) at the Brookhaven National Laboratory supporting a long standing and important DOE Program to provide scientists access to NNDC Databases. The NNDC participated as a partner in this effort.

  7. Advanced development of the Nested Fiber Filter: Phase 1, Evaluation of cleaning methods. Final report

    SciTech Connect

    Litt, R.D.; Conkle, H.N.; Glover, R.C.; Jordan, H.

    1990-08-01

    Battelle has completed Phase I of the DOE program to evaluate cleaning methods for the Nested Fiber Filter (NFF). The results of the investigations into fly ash bonding mechanisms, and mechanical vibration and acoustic vibration techniques led to the conclusion that acoustic cleaning with a pulse combustor is the preferred integrated system for high-temperature, high-pressure applications.

  8. Columbia River Stock Identification Study; Validation of Genetic Method, 1980-1981 Final Report.

    SciTech Connect

    Milner, George B.; Teel, David J.; Utter, Fred M.

    1981-06-01

    The reliability of a method for obtaining maximum likelihood estimate of component stocks in mixed populations of salmonids through the frequency of genetic variants in a mixed population and in potentially contributing stocks was tested in 1980. A data base of 10 polymorphic loci from 14 hatchery stocks of spring chinook salmon of the Columbia River was used to estimate proportions of these stocks in four different blind'' mixtures whose true composition was only revealed subsequent to obtaining estimates. The accuracy and precision of these blind tests have validated the genetic method as a valuable means for identifying components of stock mixtures. Properties of the genetic method were further examined by simulation studies using the pooled data of the four blind tests as a mixed fishery. Replicated tests with samples sizes between 100 and 1,000 indicated that actual standard deviations on estimated contributions were consistently lower than calculated standard deviations; this difference diminished as sample size increased. It is recommended that future applications of the method be preceded by simulation studies that will identify appropriate levels of sampling required for acceptable levels of accuracy and precision. Variables in such studies include the stocks involved, the loci used, and the genetic differentiation among stocks. 8 refs., 6 figs., 4 tabs.

  9. A Study of Method in Language and Culture Research; Phase II: Textual Analysis. Final Report.

    ERIC Educational Resources Information Center

    California State Univ. Foundation, Northridge.

    The development and testing of textual analysis procedures using Mexican-Spanish and Papago texts as a phase of a study of method in language and culture research are described in this research report. These procedures, which are designed to allow the examination of informational structure and cognitive content, (1) segment uniformized texts into…

  10. Factor Regression Analysis: A New Method for Weighting Predictors. Final Report.

    ERIC Educational Resources Information Center

    Curtis, Ervin W.

    The optimum weighting of variables to predict a dependent-criterion variable is an important problem in nearly all of the social and natural sciences. Although the predominant method, multiple regression analysis (MR), yields optimum weights for the sample at hand, these weights are not generally optimum in the population from which the sample was…

  11. Sub-cycle dynamics of multiphoton ionization

    NASA Astrophysics Data System (ADS)

    Telnov, Dmitry A.; Nasiri Avanaki, K.; Chu, Shih-I.

    2014-05-01

    Sub-cycle oscillatory structures are revealed in calculated time-dependent multiphoton ionization rates. Both atomic and molecular targets manifest multiple ionization bursts per one optical cycle of the laser field. Using the accurate and efficient time-dependent generalized pseudospectral method to solve the time-dependent Schrödinger equation, we have performed calculations on H, He+, H2+,and HHe2+, for the laser fields with several intensities and wavelengths in the near-infrared range (750 nm to 1064 nm). The sub-cycle structures appear a universal feature of multiphoton ionization and become well pronounced for sufficiently strong laser fields depending on the target atom or molecule. Analysis of the electron density distributions on the sub-femtosecond time scale shows several time moments per optical cycle (not necessarily corresponding to the peak values of the laser field) when significant portions of the electron density move away from the nucleus giving rise to the bursts in the ionization rate. The nature of the phenomenon can be related to ionization through different pathways, including direct ionization as well as population of the excited states by the laser field with subsequent ionization at later times. This work is partially supported by DOE.

  12. Expedient methods for rattle-proofing certain housing components. Final report

    SciTech Connect

    Schomer, P.D.; Hottman, S.D.; Kessler, F.M.; Kessler, R.K.

    1987-12-01

    Occupants of buildings located in areas of high-level impulse noise usually report that the main annoyance factor is the rattle produced by house components upon vibration. This type of noise is associated with helicopter flybys and blast overpressure from artillery and other military training operations. Methods are needed for mitigating rattles in both existing structures and future construction. This report analyzes several different elements to identify individual components contributing to rattle. Elements studied include windows, doors, wall-mounted objects, bric-a-brac, ductwork, gutters, and light fixtures, among others. In general, the primary source of rattle is any small gap between two hard surfaces that are subject to vibration from an exterior noise source. Upon excitation, these surfaces can impact each other, producing the sound. Other rattle sources are identified, and methods are recommended for eliminating or reducing noise from the individual elements.

  13. Methods of extracting hydrogen from lunar soil. Final technical report, 1 April-31 October 1988

    SciTech Connect

    Bustin, R.

    1988-10-01

    Increasing interest in establishing a lunar base has generated considerable study on the utilization of lunar resources. Because of its importance in producing water, reducing oxides, and serving as a fuel for orbital tranfer vehicles, hydrogen is of prime importance as a resource. Lowman (1985) states that hydrogen would greatly facilitate the establishment of an autonomous permanent colony, and he calls hydrogen the most valuable lunar resource. Through the centuries, hydrogen has been embedded in lunar soil by the solar wind. The hydrogen can be extracted by heating the soil to 900 C (Carr et al, 1987). In order to obtain hydrogen on the lunar surface, an extraction method must be developed which will not only be reliable but also economically feasible. Three heating methods are examined for possible use in extracting hydrogen from lunar soil.

  14. A Study of Morrison's Iterative Noise Removal Method. Final Report M. S. Thesis

    NASA Technical Reports Server (NTRS)

    Ioup, G. E.; Wright, K. A. R.

    1985-01-01

    Morrison's iterative noise removal method is studied by characterizing its effect upon systems of differing noise level and response function. The nature of data acquired from a linear shift invariant instrument is discussed so as to define the relationship between the input signal, the instrument response function, and the output signal. Fourier analysis is introduced, along with several pertinent theorems, as a tool to more thorough understanding of the nature of and difficulties with deconvolution. In relation to such difficulties the necessity of a noise removal process is discussed. Morrison's iterative noise removal method and the restrictions upon its application are developed. The nature of permissible response functions is discussed, as is the choice of the response functions used.

  15. Load Modeling and State Estimation Methods for Power Distribution Systems: Final Report

    SciTech Connect

    Tom McDermott

    2010-05-07

    The project objective was to provide robust state estimation for distribution systems, comparable to what has been available on transmission systems for decades. This project used an algorithm called Branch Current State Estimation (BCSE), which is more effective than classical methods because it decouples the three phases of a distribution system, and uses branch current instead of node voltage as a state variable, which is a better match to current measurement.

  16. Final Report-- A Novel Storage Method for Concentrating Solar Power Plants Allowing Storage at High Temperature

    SciTech Connect

    Morris, Jeffrey F.

    2014-09-29

    The main objective of the proposed work was the development and testing of a storage method that has the potential to fundamentally change the solar thermal industry. The development of a mathematical model that describes the phenomena involved in the heat storage and recovery was also a main objective of this work. Therefore, the goal was to prepare a design package allowing reliable scale-up and optimization of design.

  17. Development of deterministic transport methods for low energy neutrons for shielding in space. Final report

    SciTech Connect

    Ganapol, B.

    1993-09-01

    Transport of low energy neutrons associated with the galactic cosmic ray cascade is analyzed in this dissertation. A benchmark quality analytical algorithm is demonstrated for use with BRYNTRN, a computer program written by the High Energy Physics Division of NASA Langley Research Center, which is used to design and analyze shielding against the radiation created by the cascade. BRYNTRN uses numerical methods to solve the integral transport equations for baryons with the straight-ahead approximation, and numerical and empirical methods to generate the interaction probabilities. The straight-ahead approximation is adequate for charged particles, but not for neutrons. As NASA Langley improves BRYNTRN to include low energy neutrons, a benchmark quality solution is needed for comparison. The neutron transport algorithm demonstrated in this dissertation uses the closed-form Green's function solution to the galactic cosmic ray cascade transport equations to generate a source of neutrons. A basis function expansion for finite heterogeneous and semi-infinite homogeneous slabs with multiple energy groups and isotropic scattering is used to generate neutron fluxes resulting from the cascade. This method, called the FN method, is used to solve the neutral particle linear Boltzmann transport equation. As a demonstration of the algorithm coded in the programs MGSLAB and MGSEMI, neutron and ion fluxes are shown for a beam of fluorine ions at 1000 MeV per nucleon incident on semi-infinite and finite aluminum slabs. Also, to demonstrate that the shielding effectiveness against the radiation from the galactic cosmic ray cascade is not directly proportional to shield thickness, a graph of transmitted total neutron scalar flux versus slab thickness is shown. A simple model based on the nuclear liquid drop assumption is used to generate cross sections for the galactic cosmic ray cascade.

  18. A dual method for optimal control problems with initial and final boundary constraints.

    NASA Technical Reports Server (NTRS)

    Pironneau, O.; Polak, E.

    1973-01-01

    This paper presents two new algorithms belonging to the family of dual methods of centers. The first can be used for solving fixed time optimal control problems with inequality constraints on the initial and terminal states. The second one can be used for solving fixed time optimal control problems with inequality constraints on the initial and terminal states and with affine instantaneous inequality constraints on the control. Convergence is established for both algorithms. Qualitative reasoning indicates that the rate of convergence is linear.

  19. A dual method for optimal control problems with initial and final boundary constraints.

    NASA Technical Reports Server (NTRS)

    Pironneau, O.; Polak, E.

    1973-01-01

    This paper presents two new algorithms belonging to the family of dual methods of centers. The first can be used for solving fixed time optimal control problems with inequality constraints on the initial and terminal states. The second one can be used for solving fixed time optimal control problems with inequality constraints on the initial and terminal states and with affine instantaneous inequality constraints on the control. Convergence is established for both algorithms. Qualitative reasoning indicates that the rate of convergence is linear.

  20. Method for cutting steam heat losses during cyclic steam injection of wells. Final report

    SciTech Connect

    Gondouin, M.

    1995-12-01

    Heavy Oil is abundant in California. It is a very viscous fluid, which must be thinned in order to flow from wells at economical rates. The best method of oil viscosity reduction is by cyclic steam injection into the oil-containing rock formations. Making steam in conventional generators fueled with Natural Gas is, however, a costly process. The main objective of this Project is to reduce the cost of the required steam, per Barrel of Oil produced. This is made possible by a combination of Patented new technologies with several known methods. The best known method for increasing the production rate from oil wells is to use horizontal drainholes, which provide a much greater flow area from the oil zone into the well. A recent statistic based on 344 horizontal wells in 21 Canadian Oil fields containing Heavy Oil shows that these are, on the average six times more prolific than vertical wells. The cost of horizontal wells, however, is generally two to three times that of a vertical well, in the same field, so our second goal is to reduce the net cost of horizontal wells by connecting two of them to the same vertical casing, well head and pumping system. With such a well configuration, it is possible to get two horizontal wells for the price of about one and a half times the price of a single vertical well.

  1. Laboratory method to estimate hydrogen chloride emission potential before incineration of a waste. Final report

    SciTech Connect

    Peterson, M.R.; Albritton, J.R.; Jayanty, R.K.M.

    1990-07-01

    A laboratory method has been developed to provide an estimate of the amount of hydrogen chloride gas that will form during incineration of a waste. The method involves incineration of a sample of the waste at 900 C in a tube furnace, removal of particles from the resulting gases by filtration at 250 F (120 C), collection of hydrogen chloride gas in a water-filled impinger, and measurement of the collected HCl as chloride using a standard ion chromatography/conductimetric detection method. Duplicate experimental runs were conducted with quartz and with INCONEL components in the incineration zone of the apparatus. The two materials gave quite different results, which indicates some surface phenomenon may be involved. Results with quartz components indicated that organochlorine is essentially completely converted to HCl. Very ionic inorganic chlorides (e.g., KCl and NaCl) formed little or no HCl when incinerated in zero grade air (3ppm water and 1 ppm total hydrocarbon) but gave large amounts of HCl (20-80% conversion) if the incineration atmosphere contained 2.4-5.0% water vapor, which contains hydrogen for HCl formation. Results with less ionic inorganic chloride (FeCl3) and with chlorine in a positive oxidation state (NaCl solution) indicated significant conversion to HCl, especially in the presence of hydrogen from water vapor. In all cases, the presence of water vapor increased the amount of HCl formed, but INCONEL was judged less suitable than quartz because INCONEL gave low recovery of organohalogen as HCl.

  2. Development and application of a probabilistic evaluation method for advanced process technologies. Final report

    SciTech Connect

    Frey, H.C.; Rubin, E.S.

    1991-04-01

    The objective of this work is to develop and apply a method for research planning for advanced process technologies. To satisfy requirements for research planning, it is necessary to: (1) identify robust solutions to process design questions in the face of uncertainty to eliminate inferior design options; (2) identify key problem areas in a technology that should be the focus of further research to reduce the risk of technology failure; (3) compare competing technologies on a consistent basis to determine the risks associated with adopting a new technology; and (4) evaluate the effects that additional research might have on comparisons with conventional technology. An important class of process technologies are electric power plants. In particular, advanced clean coal technologies are expected to play a key role in the energy and environmental future of the US, as well as in other countries. Research planning for advanced clean coal technology development is an important part of energy and environmental policy. Thus, the research planning method developed here is applied to case studies focusing on a specific clean coal technology. The purpose of the case studies is both to demonstrate the research planning method and to obtain technology-specific conclusions regarding research strategies.

  3. Electron ionization of acetylene.

    PubMed

    King, Simon J; Price, Stephen D

    2007-11-07

    Relative partial ionization cross sections and precursor specific relative partial ionization cross sections for fragment ions formed by electron ionization of C2H2 have been measured using time-of-flight mass spectrometry coupled with a 2D ion-ion coincidence technique. We report data for the formation of H+, H+2, C2+, C+/C2+ 2, CH+/C2H+2, CH+2, C+2, and C2H+ relative to the formation of C2H+2, as a function of ionizing electron energy from 30-200 eV. While excellent agreement is found between our data and one set of previously published absolute partial ionization cross sections, some discrepancies exist between the results presented here and two other recent determinations of these absolute partial ionization cross sections. We attribute these differences to the loss of some translationally energetic fragment ions in these earlier studies. Our relative precursor-specific partial ionization cross sections enable us, for the first time, to quantify the contribution to the yield of each fragment ion from single, double, and triple ionization. Analysis shows that at 50 eV double ionization contributes 2% to the total ion yield, increasing to over 10% at an ionizing energy of 100 eV. From our ion-ion coincidence data, we have derived branching ratios for charge separating dissociations of the acetylene dication. Comparison of our data to recent ab initio/RRKM calculations suggest that close to the double ionization potential C2H2+2 dissociates predominantly on the ground triplet potential energy surface (3Sigma*g) with a much smaller contribution from dissociation via the lowest singlet potential energy surface (1Delta g). Measurements of the kinetic energy released in the fragmentation reactions of C2H2+2 have been used to obtain precursor state energies for the formation of product ion pairs, and are shown to be in good agreement with available experimental data and with theory.

  4. Advancing Reactive Tracer Methods for Measurement of Thermal Evolution in Geothermal Reservoirs: Final Report

    SciTech Connect

    Mitchell A. Plummer; Carl D. Palmer; Earl D. Mattson; Laurence C. Hull; George D. Redden

    2011-07-01

    The injection of cold fluids into engineered geothermal system (EGS) and conventional geothermal reservoirs may be done to help extract heat from the subsurface or to maintain pressures within the reservoir (e.g., Rose et al., 2001). As these injected fluids move along fractures, they acquire heat from the rock matrix and remove it from the reservoir as they are extracted to the surface. A consequence of such injection is the migration of a cold-fluid front through the reservoir (Figure 1) that could eventually reach the production well and result in the lowering of the temperature of the produced fluids (thermal breakthrough). Efficient operation of an EGS as well as conventional geothermal systems involving cold-fluid injection requires accurate and timely information about thermal depletion of the reservoir in response to operation. In particular, accurate predictions of the time to thermal breakthrough and subsequent rate of thermal drawdown are necessary for reservoir management, design of fracture stimulation and well drilling programs, and forecasting of economic return. A potential method for estimating migration of a cold front between an injection well and a production well is through application of reactive tracer tests, using chemical whose rate of degradation is dependent on the reservoir temperature between the two wells (e.g., Robinson 1985). With repeated tests, the rate of migration of the thermal front can be determined, and the time to thermal breakthrough calculated. While the basic theory behind the concept of thermal tracers has been understood for some time, effective application of the method has yet to be demonstrated. This report describes results of a study that used several methods to investigate application of reactive tracers to monitoring the thermal evolution of a geothermal reservoir. These methods included (1) mathematical investigation of the sensitivity of known and hypothetical reactive tracers, (2) laboratory testing of novel

  5. Two- and three-photon double ionization of lithium

    NASA Astrophysics Data System (ADS)

    Armstrong, G.; Schuricke, M.; Veeravalli, G.; Dornes, Ch.; Zhu, G.; Joachimsmeyer, K.; Treusch, R.; Dorn, A.; Colgan, J.

    2012-06-01

    Motivated by current FEL experiments at FLASH, we present triple differential cross sections and recoil ion momentum distributions for two- and three-photon double ionization of the 1s^22s ^2S ground state of lithium at a photon energy of 50 eV. The time-dependent close-coupling (TDCC) method is used to solve the two-electron time-dependent Schr"odinger equation in full dimensionality. The double ionization process is treated as a two-active-electron process, where the ``active'' 1s and 2s electrons move in the field of the ``frozen-core'' Li^2+ 1s state. Recent experimental measurements of recoil ion momentum distributions have observed features associated with the absorption of both two and three photons. This work provides the first TDCC calculations to date of such two- and three-photon double ionization processes in lithium. The accurate treatment of these processes requires a detailed description of the final continuum containing both singlet and triplet S, P, D and F waves. We examine triple differential cross sections as a function of electron energy sharing for a variety of angular configurations. We also compare our calculated recoil ion momentum distributions with experimental measurements, providing the first such comparison for two- and three-photon processes.

  6. Alkali metal ionization detector

    DOEpatents

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  7. "Magic" Ionization Mass Spectrometry.

    PubMed

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The “magic” that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  8. "Magic" Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The "magic" that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  9. Uncertainty analysis of the Measured Performance Rating (MPR) method. Final report

    SciTech Connect

    Not Available

    1993-11-01

    A report was commissioned by the New York State Energy Research and Development Authority and the Electric Power Research Institute to evaluate the uncertainties in the energy monitoring method known as measured performance rating (MPR). The work is intended to help further development of the MPR system by quantitatively analyzing the uncertainties in estimates of the heat loss coefficients and heating system efficiencies. The analysis indicates that the MPR should detect as little as a 7 percent change in the heat loss coefficients and heating system efficiencies. The analysis indicate that the MPR should be able to detect as little as a 7 percent change in the heat loss coefficient at 95 percent confidence level. MPR appears sufficiently robust for characterizing common weatherization treatments; e.g., increasing attic insulation from R-7 to R-19 in a typical single-story, 1,100 sq. ft. house resulting in a 19 percent reduction in heat loss coefficient. Furnace efficiency uncertainties ranged up to three times those of the heat loss coefficients. Measurement uncertainties (at the 95 percent confidence level) were estimated to be from 1 to 5 percent for heat loss coefficients and 1.5 percent for a typical furnace efficiency. The analysis also shows a limitation in applying MPR to houses with heating ducts in slabs on grade and to those with very large thermal mass. Most of the uncertainties encountered in the study were due more to the methods of estimating the ``true`` heat loss coefficients, furnace efficiency, and furnace fuel consumption (by collecting fuel bills and simulating two actual houses) than to the MPR approach. These uncertainties in the true parameter values become evidence for arguments in favor of the need of empirical measures of heat loss coefficient and furnace efficiency, like the MPR method, rather than arguments against.

  10. Carbonaceous species methods comparison study: University of Minnesota results. Final report

    SciTech Connect

    McMurry, P.H.; Zhang, X.

    1988-10-01

    The Carbon Methods Comparison Study conducted during August 12-20, 1986 at Citrus College, Glendora, CA in the Los Angeles basin compared analytical methodologies for analyzing the carbon content of aerosol samples, as well as compared measurements acquired with different samples. Five samplers, including a multistage microorifice uniform deposit impactor (MOUDI), a conventional quartz filter, a specially designed electrostatic precipitator (ESP), and 2 identical single stage MOUDIs were used. One of the single stage MOUDIs was used as a fine particle sampler; the second was used in experiments to investigate possible sampling articles. The results are summarized and discussed.

  11. C deg continuity elements by Hybrid Stress method. M.S. Thesis, 1982 Final Report

    NASA Technical Reports Server (NTRS)

    Kang, David Sung-Soo

    1991-01-01

    An intensive study of the assumed variable distribution necessary for the Assumed Displacement Formulation, the Hellinger-Reissner Formulation, and the Hu-Washizu Formulation is made in a unified manner. With emphasis on physical explanation, a systematic method for the Hybrid Stress element construction is outlined. The numerical examples use four and eight node plane stress elements and eight and twenty node solid elements. Computation cost study indicates that the hybrid stress element derived using recently developed Uncoupled Stress Formulation is comparable in CPU time to the Assumed Displacement element. Overall, main emphasis is placed on providing a broader understanding of the Hybrid Stress Formulation.

  12. Test methods for the dynamic mechanical properties of polymeric materials. Final report

    SciTech Connect

    Baker, G.K.

    1980-06-01

    Various test geometries and procedures for the dynamic mechanical analysis of polymers employing a mechanical spectrometer have been evaluated. The methods and materials included in this work are forced torsional pendulum testing of Kevlar/epoxy laminates and rigid urethane foams, oscillatory parallel plate testing to determine the kinetics of the cure of VCE with Hylene MP, oscillatory compressive testing of B-3223 cellular silicone, and oscillatory tensile testing of Silastic E and single Kevlar filaments. Fundamental dynamic mechanical properties, including the storage and loss moduli and loss tangent of the materials tested, were determined as a function of temperature and sometimes of frequency.

  13. Accelerated screening methods for determining chemical and thermal stability of refrigerant-lubricant mixtures, Part 1: Method assessment. Final report

    SciTech Connect

    Kauffman, R.

    1993-04-01

    This report presents results of a literature search performed to identify analytical techniques suitable for accelerated screening of chemical and thermal stabilities of different refrigerant/lubricant combinations. Search focused on three areas: Chemical stability data of HFC-134a and other non-chlorine containing refrigerant candidates; chemical stability data of CFC-12, HCFC-22, and other chlorine containing refrigerants; and accelerated thermal analytical techniques. Literature was catalogued and an abstract was written for each journal article or technical report. Several thermal analytical techniques were identified as candidates for development into accelerated screening tests. They are easy to operate, are common to most laboratories, and are expected to produce refrigerant/lubricant stability evaluations which agree with the current stability test ANSI/ASHRAE (American National Standards Institute/American Society of Heating, Refrigerating, and Air-Conditioning Engineers) Standard 97-1989, ``Sealed Glass Tube Method to Test the Chemical Stability of Material for Use Within Refrigerant Systems.`` Initial results of one accelerated thermal analytical candidate, DTA, are presented for CFC-12/mineral oil and HCFC-22/mineral oil combinations. Also described is research which will be performed in Part II to optimize the selected candidate.

  14. Development of a method for evaluating carbon dioxide miscible flooding prospects. Final report

    SciTech Connect

    Green, D.W.; Swift, G.W.

    1985-03-01

    Research was undertaken to develop a method of evaluating reservoirs as prospects for carbon dioxide flooding. Evaluation was to be based on a determination of miscibility pressure and displacement efficiency under idealized conditions. To reach the objective, project work was divided into five areas: (1) conducting of phase-equilibrium studies of carbon dioxide with synthetic oils; (2) application of an equation of state to simulate the phase behavior of carbon dioxide - oil systems; (3) conducting of linear displacements of crude oils and synthetic oils by carbon dioxide in a slim-tube apparatus; (4) application of the equation of state, the phase-behavior data and slim-tube data to develop a method of screening reservoirs for carbon dioxide flooding based on determination of minimum miscibility pressure and displacement efficiency; (5) development of a one-dimensional mathematical model, based on the equation of state, for application in conjunction with the results of Parts 1 to 4. The accomplishments for these five areas are discussed in five chapters. 44 references, 90 figures, 42 tables.

  15. Cost-effective method for determining the grindability of ceramics. Final report

    SciTech Connect

    Guo, C.; Chand, R.H.

    1997-02-01

    The objective of this program was to develop a cost-effective method to determine the grindability of ceramics leading to cost-effective methods for machining such ceramics. In this first phase of activity, Chand Kare Technical Ceramics directed its efforts towards development of a definition for ceramic grindability, design of grindability-test experiments, and development of a ceramics-grindability test system (CGTS). The grindability study also included the establishment of the correlation between the grindability and conventional grinding practices. The above goals were achieved. A definition based on material removal rate under controlled force grinding was developed. Three prototypes CGTSs were developed and tested; suitable design was identified. Based on this, a fully automatic CGTS was developed and is ready for delivery to Oak Ridge National Laboratory. Comprehensive grindability tests for various commercially available engineering ceramics were conducted. Experimental results indicated that ceramics have significantly different grindabilities even though their mechanical properties were not significantly different. This implies that grindability of ceramics can be greatly improved. Further study is needed to establish correlations between microstructure and grindability. Therefore, grindability should be evaluated during the development of new ceramics or improvement of existing ones. In this report, the development of the ceramic-grindability definition, the development of CGTS, extensive grindability results, and the preliminary correlation between grindability and mechanical properties (such as flexural strength, hardness, elastic modulus, and fracture toughness) were summarized.

  16. Methods for evaluating and ranking transportation energy conservation programs. Final report

    SciTech Connect

    Not Available

    1981-04-30

    Methods for comparative evaluations of the Office of Transportation programs designed to help achieve significant reductions in the consumption of petroleum by different forms of transportation while maintaining public, commercial, and industrial mobility are described. Assessments of the programs in terms of petroleum savings, incremental costs to consumers of the technologies and activities, probability of technical and market success, and external impacts due to environmental, economic, and social factors are inputs to the evaluation methodologies presented. The methods described for evaluating the programs on a comparative basis are three ranking functions and a policy matrix listing important attributes of the programs and the technologies and activities with which they are concerned and include the traditional net present value measure which computes the present worth of petroleum savings less the present worth of costs. This is modified by dividing by the present value of DOE funding to obtain a net present value per program dollar, which is the second ranking function. The third ranking function is broader in that it takes external impacts into account and is known as the comprehensive ranking function. Procedures are described for making computations of the ranking functions and the attributes that require computation. Computations are made for the electric vehicle, Stirling engine, gas turbine, and MPG mileage guide program. (MCW)

  17. Final program evaluation methods and results of a National Lymphedema Management Program in Togo, West Africa.

    PubMed

    Ziperstein, Josh; Dorkenoo, Monique; Datagni, Michel; Drexler, Naomi; Murphy, Monica; Sodahlon, Yao; Mathieu, Els

    2014-06-01

    In order to eliminate Lymphatic Filariasis (LF) as a public health problem, the World Health Assembly recommends an approach which includes interruption of transmission of infection and the alleviation of morbidity. In 2000, the Togolese National Program to Eliminate Lymphatic Filariasis (PNELF) started the annual mass drug administrations and in 2007, the program added a morbidity component for the management of lymphedema. This manuscript describes the methods of an evaluation aimed at assessing the strengths and weaknesses of the Togolese National Lymphedema Morbidity Program. The evaluation was conducted through in-depth interviews with stakeholders at each programmatic level. Interviews focused on message dissemination, health provider training, patient self-care practices, social dynamics, and program impact. The evaluation demonstrated that the program strengths include the standardization and in-depth training of health staff, dissemination of the program's treatment message, a positive change in the community's perception of lymphedema, and successful patient recruitment and training in care techniques. The lessons learned from this evaluation helped to improve Togo's program, but may also provide guidance and strategies for other countries desiring to develop a morbidity program. The methods of program evaluation described in this paper can serve as a model for monitoring components of other decentralized national health programs in low resource settings.

  18. Final report on DSA methods for monitoring alumina in aluminum reduction cells with cermet anodes

    NASA Astrophysics Data System (ADS)

    Windisch, C. F., Jr.

    1992-04-01

    The Sensors Development Program was conducted at the Pacific Northwest Laboratory (PNL) for the US Department of Energy, Office of Industrial Processes. The work was performed in conjunction with the Inert Electrodes Program at PNL. The objective of the Sensors Development Program in FY 1990 through FY 1992 was to determine whether methods based on digital signal analysis (DSA) could be used to measure alumina concentration in aluminum reduction cells. Specifically, this work was performed to determine whether useful correlations exist between alumina concentration and various DSA-derived quantification parameters, calculated for current and voltage signals from laboratory and field aluminum reduction cells. If appropriate correlations could be found, then the quantification parameters might be used to monitor and, consequently, help control the alumina concentration in commercial reduction cells. The control of alumina concentration is especially important for cermet anodes, which have exhibited instability and excessive wear at alumina concentrations removed from saturation.

  19. Superelement methods in high temperature metal matrix composites. Final Report; M.S. Thesis, 1989

    NASA Technical Reports Server (NTRS)

    Trowbridge, Daniel

    1991-01-01

    A study into fiber fracture and debonding in metal matrix composites is conducted using the finite element method. The superelement finite element technique was used to model a metal matrix composite under various loading condition and with varying degrees of fiber debonding. The use of superelement saved many man hours by allowing for alteration of only the primary superelement to manipulate partial bonding for the entire model. The composite's material properties were calculated and the effects of fiber debonding on these properties were noted. The internal stress state of the composite while under various loads was also studied. Special interest was devoted to the change in stress state as a result of increasing fiber debonding.

  20. Final report on DSA methods for monitoring alumina in aluminum reduction cells with cermet anodes

    SciTech Connect

    Windisch, C.F. Jr.

    1992-04-01

    The Sensors Development Program was conducted at the Pacific Northwest Laboratory (PNL) for the US Department of Energy, Office of Industrial Processes. The work was performed in conjunction with the Inert Electrodes Program at PNL. The objective of the Sensors Development Program in FY 1990 through FY 1992 was to determine whether methods based on digital signal analysis (DSA) could be used to measure alumina concentration in aluminum reduction cells. Specifically, this work was performed to determine whether useful correlations exist between alumina concentration and various DSA-derived quantification parameters, calculated for current and voltage signals from laboratory and field aluminum reduction cells. If appropriate correlations could be found, then the quantification parameters might be used to monitor and, consequently, help control the alumina concentration in commercial reduction cells. The control of alumina concentration is especially important for cermet anodes, which have exhibited instability and excessive wear at alumina concentrations removed from saturation.

  1. Final report: ES11: The 23rd Annual Workshop on Electronic Structure Methods

    SciTech Connect

    Rappe, Andrew M.

    2011-08-31

    ES11: the 23rd Annual Workshop on Electronic Structure Methods was held from June 6-9, 2011 at the University of Pennsylvania. The local organizing committee (see Section II) led by PI Andrew M. Rappe supervised the organization of the conference, before, during, and after the meeting itself. The national organizing committee set the technical program of talks, and provided support and advice in various ways. The conference was well-attended (see Section III). An important feature of this conference was a series of panel discussions (see Section IV) to discuss the field of electronic structure and to set new directions. The technical program was of extraordinarily high quality (see Section V). The host institution, the University of Pennsylvania, provided a supportive environment for this meeting (see Section VI).

  2. Critical evaluation and comparison of measurement methods for nitrogenous compounds in the atmosphere. Final report

    SciTech Connect

    Grosjean, D.

    1982-01-01

    This report describes the method and results of an intensive field study of atmospheric nitrogenous pollutants conducted in Claremont, California, a Los Angeles smog receptor site, during selected September and October 1980 photochemical episodes. Parameters measured included nitric oxide and nitrogen dioxide, peroxyacetylnitrate, and refined particulate nitrate and nitric acid. In addition, a limited number of refined particulate samples collected on quartz filters were analyzed for sulfate and for total carbon. All sampling and monitoring instruments were calibrated on-site following Environmental Research and Technology's Standard Operating Procedures. Laboratory quality assurance protocols included appropriate calibrations, analysis of blank and field control filters, analysis of EPA audit samples, and replicate analyses. Sampling control experiments included a number of parallel collections on Teflon filters.

  3. Comparison of void-measurement methods for carbon/epoxy composites. Final report

    SciTech Connect

    Ghiorse, S.R.

    1991-04-01

    This report studies four destructive measurement techniques for determining void volume fraction in CFRP composites. Two approaches to void measurement were taken: density determination/matrix digestion (DD/MD), and optical image analysis. Within each approach two techniques were studied. In the DD/MD approach, the water buoyancy technique WBY0 (see ASTM D 792) and density gradient technique (DGT) (see ASTM D 1505) were investigated. In the image analysis approach a Dapple Image Analyzer, and the more automated Omnimet Image Analyzer, techniques were investigated. It was found that true or absolute void content is quite difficult to measure regardless of the technique used. However, when making relative measurements between like specimens void content comparisons are reliable and practical to obtain. The WBT recorded consistently lower void content data than the DGT; it was also found to be less precise. For routine CFRP, void content determination, where relative comparisons are sufficient and high precision is not an issue, the WBT is recommended as it is practical to implement. When high precision is needed, the DGT is recommended. Image analysis methods produce highly localized data, but it is likely that they approximate true void content more closely than the DD/MD method because the void measurement, though actually a measure of void area, is direct. For more critical void content measurement where accuracy, as well as precision are required, a highly automated version of an image analysis technique, like the Omnimet, which scans a large number of cross sections is recommended. At present, this appears to be the best procedure available to determine true void content.

  4. Linear and nonlinear dynamic analysis by boundary element method. Ph.D. Thesis, 1986 Final Report

    NASA Technical Reports Server (NTRS)

    Ahmad, Shahid

    1991-01-01

    An advanced implementation of the direct boundary element method (BEM) applicable to free-vibration, periodic (steady-state) vibration and linear and nonlinear transient dynamic problems involving two and three-dimensional isotropic solids of arbitrary shape is presented. Interior, exterior, and half-space problems can all be solved by the present formulation. For the free-vibration analysis, a new real variable BEM formulation is presented which solves the free-vibration problem in the form of algebraic equations (formed from the static kernels) and needs only surface discretization. In the area of time-domain transient analysis, the BEM is well suited because it gives an implicit formulation. Although the integral formulations are elegant, because of the complexity of the formulation it has never been implemented in exact form. In the present work, linear and nonlinear time domain transient analysis for three-dimensional solids has been implemented in a general and complete manner. The formulation and implementation of the nonlinear, transient, dynamic analysis presented here is the first ever in the field of boundary element analysis. Almost all the existing formulation of BEM in dynamics use the constant variation of the variables in space and time which is very unrealistic for engineering problems and, in some cases, it leads to unacceptably inaccurate results. In the present work, linear and quadratic isoparametric boundary elements are used for discretization of geometry and functional variations in space. In addition, higher order variations in time are used. These methods of analysis are applicable to piecewise-homogeneous materials, such that not only problems of the layered media and the soil-structure interaction can be analyzed but also a large problem can be solved by the usual sub-structuring technique. The analyses have been incorporated in a versatile, general-purpose computer program. Some numerical problems are solved and, through comparisons

  5. Instantaneous and continuous measurement of /sup 14/C-labeled substrate oxidation to /sup 14/CO2 by minute tissue specimens: an ionization chamber method

    SciTech Connect

    Davidson, W.D.; Klein, K.L.; Kurokawa, K.; Soll, A.H.

    1981-06-01

    The vibrating reed electrometer and ionization chamber have been adapted for the instantaneous and continuous measurement of /sup 14/C-labeled substrate oxidation to /sup 14/CO2 by minute quantities of isolated tissues. This modified technique, utilizing a ''closed'' circulation incubation system, is 10-50 times as sensitive as the previously described ''open'' circulation techniques. Substrate oxidation curves are described for human erythrocytes and polymorphonuclear leucocytes, canine parietal cells and isolated segments of the rat nephron. This apparatus should prove to be a useful tool for metabolic studies of small quantities of isolated tissue.

  6. Quantum mechanical calculations related to ionization and charge transfer in DNA

    NASA Astrophysics Data System (ADS)

    Cauët, E.; Valiev, M.; Weare, J. H.; Liévin, J.

    2012-07-01

    Ionization and charge migration in DNA play crucial roles in mechanisms of DNA damage caused by ionizing radiation, oxidizing agents and photo-irradiation. Therefore, an evaluation of the ionization properties of the DNA bases is central to the full interpretation and understanding of the elementary reactive processes that occur at the molecular level during the initial exposure and afterwards. Ab initio quantum mechanical (QM) methods have been successful in providing highly accurate evaluations of key parameters, such as ionization energies (IE) of DNA bases. Hence, in this study, we performed high-level QM calculations to characterize the molecular energy levels and potential energy surfaces, which shed light on ionization and charge migration between DNA bases. In particular, we examined the IEs of guanine, the most easily oxidized base, isolated and embedded in base clusters, and investigated the mechanism of charge migration over two and three stacked guanines. The IE of guanine in the human telomere sequence has also been evaluated. We report a simple molecular orbital analysis to explain how modifications in the base sequence are expected to change the efficiency of the sequence as a hole trap. Finally, the application of a hybrid approach combining quantum mechanics with molecular mechanics brings an interesting discussion as to how the native aqueous DNA environment affects the IE threshold of nucleobases.

  7. Method validation for the analysis of 169 pesticides in soya grain, without clean up, by liquid chromatography-tandem mass spectrometry using positive and negative electrospray ionization.

    PubMed

    Pizzutti, Ionara R; de Kok, André; Zanella, Renato; Adaime, Martha B; Hiemstra, Maurice; Wickert, Cristine; Prestes, Osmar D

    2007-02-23

    Part of a comprehensive study on the comparison of different extraction methods, GC-MS(/MS) and LC-MS/MS detection methods and modes, for the analysis of soya samples is described in this paper. The validation of an acetone-based extraction method for analysis of 169 pesticides in soya, using LC-MS/MS positive and negative electrospray ionisation (ESI) mode, is reported. Samples (5 g) were soaked with 10 g water and subsequently extracted with 100 mL of a mixture of acetone, dichloromethane and light petroleum (1:1:1), in the presence of 15 g anhydrous sodium sulphate. After centrifugation, aliquots of the extract were evaporated and reconstituted in 1.0 mL of methanol, before direct injection of the final extract (corresponding with 0.05 g soya mL(-1)) into the LC-MS/MS system. Linearity, r(2) of calibration curves, instrument limit of detection/quantitation (LOD/LOQ) and matrix effect were evaluated, based on seven concentrations measured in 6-fold. Good linearity (at least r(2)> or =0.99) of the calibration curves was obtained over the range from 0.1 or 0.25 to 10.0 ng mL(-1), corresponding with pesticide concentrations in soya bean extract of 2 or 5-200 microg kg(-1). Instrument LOD values generally were 0.1 or 0.25 ng mL(-1). Matrix effects were negligible for approximately 90% of the pesticides. The accuracy, precision and method LOQ were determined via recovery experiments, spiking soya at 10, 50, 100 microg kg(-1), six replicates per level. In both ESI modes, method LOQ values were mostly 10 or 50 microg kg(-1) and more than 70% of pesticides analysed by each mode met the acceptability criteria of recovery (70-120%) and RSD (< or =20%), at one or more of the three levels studied. A fast, easy and efficient method with acceptable performance was achieved for a difficult matrix as soya, without cleanup.

  8. Chemi-ionization for Enhanced Plasma Densities

    NASA Astrophysics Data System (ADS)

    Ard, S.

    2016-12-01

    The Air Force has long considered ways of creating enhanced plasma density as a method of mitigating the detrimental effects of ionospheric density irregularities. Numerous easily photo-ionizable molecules have been released for study in this regard, yet this approach is inherently limited to daytime use. Recently attention has turned towards chemi-ionization. Several lanthanide metal oxides have bond strengths greater than their IP, such that M + O → MO+ + e- becomes energetically accessible. In 2013 the Metal Oxide Space Cloud (MOSC) mission released vaporized samarium in the lower ionosphere to study its potential as a chemi-ionization agent with atomic oxygen. While successful at producing enhanced densities, several results created questions about the underlying chemistry. This talk will focus on our lab's efforts supporting these releases, both in analysis of the principal thermochemistry and its effects on assessment of previous results, as well as ongoing experiments considering the potential of other chemi-ionization systems for future experiments.

  9. Ionization and positronium formation in noble gases

    SciTech Connect

    Marler, J.P.; Sullivan, J.P.; Surko, C.M.

    2005-02-01

    Absolute measurements are presented for the positron-impact cross sections for direct ionization and positronium formation of noble gas atoms in the range of energies from threshold to 90 eV. The experiment uses a cold, trap-based positron beam and the technique of studying positron scattering in a strong magnetic field. The current data show generally good, quantitative agreement with previous measurements taken using a qualitatively different method. However, significant differences in the cross sections for both direct ionization and positronium formation are also observed. An analysis is presented that yields another, independent measurement of the direct ionization and positronium formation cross sections that is in agreement with the present, direct measurements to within {+-}10% for argon, krypton, and xenon. Comparison with available theoretical predictions yields good quantitative agreement for direct ionization cross sections, and qualitative agreement in the case of positronium formation.

  10. Computational methods for stellerator configurations. Final report, May 15, 1989--November 14, 1992

    SciTech Connect

    Betancourt, O.

    1992-04-01

    This project had two main objectives. The first one was to continue to develop computational methods for the study of three dimensional magnetic confinement configurations. The second one was to collaborate and interact with researchers in the field who can use these techniques to study and design fusion experiments. The first objective has been achieved with the development of the spectral code BETAS and the formulation of a new variational approach for the study of magnetic island formation in a self consistent fashion. The code can compute the correct island width corresponding to the saturated island, a result shown by comparing the computed island with the results of unstable tearing modes in Tokamaks and with experimental results in the IMS Stellarator. In addition to studying three dimensional nonlinear effects in Tokamaks configurations, these self consistent computed island equilibria will be used to study transport effects due to magnetic island formation and to nonlinearly bifurcated equilibria. The second objective was achieved through direct collaboration with Steve Hirshman at Oak Ridge, D. Anderson and R. Talmage at Wisconsin as well as through participation in the Sherwood and APS meetings.

  11. Development of methods for analyzing organics in fly ash. Final report

    SciTech Connect

    Griest, W.H.; Tomkins, B.A.; Caton, J.E.

    1986-09-01

    This project developed methodology for analyzing polycyclic aromatic hydrocarbons (PAH) and other organic compounds in airborne fly ash from coal-fired power plants. Stack ash samples were used as surrogates for fly ash in sorptivity studies and development of analytical methods. A major finding of this project was the identification of carbonaceous particles, ranging from uncombusted coal to coal coke, as the species principally responsible for the strong sorptivity of ash for PAH. The carbonaceous particles also influence the distribution of surface area and organic matter in the ash, and may provide a transport mechanism for the emitted organic matter from coal combustion. The total organic content of the carbonaceous particles ranged up to 1.6 mass %. Several procedures for the determination of organic matter on ash were developed and evaluated. These ranged from gas chromatographic (GC) screening procedures featuring derivatized solvent extracts and thermal desorptions to more complex sequential procedures involving semipreparative scale high-performance liquid chromatographic (HPLC) fractionation followed by GC or analytical scale HPLC analysis. A preliminary investigation was conducted on the nature of the 60 to 80% off the organic matter (estimated from gravimetric or total organic carbon measurements) which is unaccounted for using current chromatographic procedures. Size-exclusion chromatography and spectroscopic characterization of solvent extracts indicated the presence of oxygenated species with apparent molecular masses 200 to 1000.

  12. Dispersion measurement as a method of quantifying geologic characterization and defining reservoir heterogeneity. Final report

    SciTech Connect

    Menzie, D.E.

    1995-05-01

    The main objective of this research project is to investigate dispersion as a method of quantifying geological characterization and defining reservoir heterogeneity in order to enhance crude oil recovery. The dispersion of flow of a reservoir rock (dispersion coefficient and dispersivity) was identified as one of the physical properties of a reservoir rock by measuring the mixing of two miscible fluids, one displacing the other in a porous medium. A rock was 100% saturated with a resident fluid and displaced by a miscible fluid of equal viscosity and equal density. Some specific experiments were performed with unequal densities. Produced fluid was analyzed by refractometer, nuclear reaction, electrical conductivity and X-ray scan. Several physical and flow characteristics were measured on the sand rock sample in order to establish correlations with the measured dispersion property. Absolute permeability, effective porosity, relative permeability, capillary pressure, the heterogeneity factor and electrical conductivity were used to better understand the flow system. Linear, transverse, 2-D and 3-D dispersions were measured and used to characterize the rock heterogeneity of the flow system. A new system of measuring dispersion was developed using a gas displacing gas system in a porous medium. An attempt was also made to determine the dispersion property of an actual reservoir from present day well log data on a producing well. 275 refs., 102 figs., 17 tabs.

  13. Development of improved methods for locating large areas of bypassed oil in Louisiana. Final report

    SciTech Connect

    Bourgoyne, A.T. Jr.; Kimbrell, C.

    1994-07-01

    The primary objective of the project was to develop a predictive method for locating Pockets of bypassed mobile oil and estimating the volume of this resource. A secondary objective of the project was to transfer the learned technology to small independent operators who drill a majority of the domestic wells but lack access to a research staff. Another objective was to develop a format for compiling data on Louisiana reservoirs in a form that can be used by government and industry to evaluate the resource and plan future activities. The format developed will be demonstrated using data compiled in the bypassed oil study for selected reservoirs. The project was being funded over a three-year period and was jointly funded by the DOE and the state of Louisiana. The objectives of the project were accomplished using an interdisciplinary approach which included the disciplines of engineering, geology, and computer science. The work was organized into the following major tasks: Selection of reservoirs for study of bypassed oil potential; development of improved reservoir simulator for bypassed oil prospecting; an interdisciplinary reservoir characterization study of Louisiana reservoirs; active modelling of bypassed oil for three Louisiana reservoirs; and technology transfer activities.

  14. Development of on-farm oil recovery and processing methods: Final report

    SciTech Connect

    Goodrum, J.W.; Kilgo, M.B.

    1987-09-02

    Using supercritical carbon dioxide (SC-CO2), peanut oil was extracted from ground peanuts at pressures of 2000 to 10,000 psi and temperatures of 25-120/degree/ C. Above 6000 psi, increasing the temperature to the maximum possible without heavily charring the peanuts (120/degree/C) significantly increased the initial extraction rate. Increasing the pressure at constant temperature increased the rate. At higher temperatures (75/degree/ C and above) roasting began to occur, however, this was not detrimental to the extraction rate or overall oil recovery. Decreasing the particle size increases the overall yield per batch of peanuts as seen in both the half factorial and particle size experiments. Increasing the moisture increases the amount of volatiles lost. The flow rate does not affect the solubility, percent oil recovered or volatiles lost for flow rates of 40 to 60 liters CO2/minute at STP. Recovery of peanut and rapeseed oil with a combined process of partial recovery in a screw press plus extraction of the remaining oil with SC-CO2 is technically a viable alternative to other oil recovery methods. Oil recoveries of 95% (peanuts) and 75% (rapeseed) have been demonstrated. The initial extraction rate for rapeseed was consistently lower than the rate for peanuts at the same extraction temperature and pressure. No differences in SC-CO2 extraction rates or yields were found between Dwarf Essex and Cascade varieties of rapeseed. 8 refs., 17 figs., 5 tabs.

  15. Study of methods to stimulate private investment in hospital energy conservation. Final report

    SciTech Connect

    Morrow, M.J.; Schooler, G.J.; Maturi, R.A.; Raichel, T.M.

    1984-01-01

    Hospital energy conservation can address two societal concerns - persistent health care cost inflation and excessive energy use. While hospitals can achieve some energy savings by implementing no-cost or low-cost changes in building operations and maintenance, substantial additional savings can be achieved by investing in energy conservation capital projects. In recent years, non-profit hospitals have received assistance in financing these capital projects from the Department of Energy schools and hospitals matching grants program. The DOE program, however, has experienced substantial funding cutbacks. To continue widespread implementation of hospital energy conservation capital projects, greater private sector investment will be required. The Blue Cross and Blue Shield Association and DOE conceived the Study of Methods to Stimulate Private Investment in Hospital Energy Conservation to facilitate increased hospital energy conservation investment through private sector initiatives. The focus of the study was energy conservation investment by private, non-profit hospitals. These hospitals constitute the largest segment of the hospital industry. Many of the findings about energy conservation investment in private, non-profit hospitals also apply to government-owned and investor-owned hospitals. The major findings are as follows: A major opportunity exists to achieve widespread hospital energy conservation investment over the next five to ten years; private sector financing arrangements represent a means of realizing this opportunity; several factors presently inhibit hospitals and investors from entering into energy conservation financing transactions; and state and federal initiatives can help create an environment more conducive to private financing of hospital energy conservation.

  16. Machine self-teaching methods for parameter optimization. Final report, October 1984-August 1986

    SciTech Connect

    Dillard, R.A.

    1986-12-01

    The problem of determining near-optimum parameter-control logic is addressed for cases where a sensor or communication system is highly flexible and the logic cannot be determined analytically. A system that supports human-like learning of optimum parameters is outlined. The major subsystems are (1) a simulation system (described for a radar example), (2) a performance monitoring system, (3) the learning system, and (4) the initial knowledge used by all subsystems. The initial knowledge is expressed modularly as specifications (e.g., radar constraints, performance measures, and target characteristics), relationships (among parameters, intermediate measures, and component performance measures), and formulas. The intent of the learning system is to relieve the human from the very tedious trial-and-error process of examining performance, selecting and applying curve-fitting methods, and selecting the next trial set of parameters. A learning system to design a simple radar meeting specific performance constraints is described in detail, for experimental purposes, in generic object-based code.

  17. Evaluation of methods of reducing permeability in porous media by in situ polymer treatments. Final report

    SciTech Connect

    Wilhite, G.P.; Green, D.W.; Young, T.S.; Thiele, J.L.; Michnick, M.J.; Vossoughi, S.; Terry, R.E.

    1986-02-01

    Several processes have been developed to reduce the permeability of reservoir rocks using high-molecular-weight, water-soluble polymers. This report describes a study of two processes which are used commercially to cross link polyacrylamides. Both processes are based upon the controlled release of multivalent metal ions which form a ''crosslink'' of some form between polymers. The first process, called the ''chromium redox process'', consists of the displacement of a polymer slug containing chromium in the +6 oxidation state, followed by a slug of polymer containing a reducing agent. A reaction occurs when the two slugs mix with Cr(VI) being reduced to Cr(III). The Cr(III) reacts with the polymer to form a gel. The second process, called the combination process, consists of the sequential injection of slugs containing polymer, aluminum citrate and polymer followed by resumption of water injection. The research described in this report investigated these two methods of reducing the permeability of porous rocks using polyacrylamides. Research was conducted on properties of bulk gels as they formed as well as in situ gelation in sandpacks and Berea core material. The research was organized in six parts: (1) characterization of gel systems; (2) correlation of gelation times and process variables for chromium(III) systems; (3) kinetics of reactions involving reduction of chromium(VI); (4) rheological studies of gelling processes; (5) insitu gelation of chromium(III) systems; and (6) permeability reduction with alternate slugs of aluminum citrate and polymer. Progress reports in each of these areas are presented. 71 figs., 81 tabs.

  18. New methods and chemicals to control regrowth in trees. Final report

    SciTech Connect

    Domir, S.C.

    1982-09-01

    A study was made of new methods and chemicals for controlling growth in trees. As a result of this research program, a portable, air-powered injection system was developed, numerous growth retardants were tested in both the greenhouse and the field, and information was gathered on the transport and metabolic fate of injected chemicals. Using young, containerized seedlings in the greenhouse, numerous chemicals were screened for their potential as growth retardants. The most consistently effective chemicals tested over a wide range of tree species were maleic hydrazide (Slo Gro, MH) and dikegulac (Atrinal). At appropriate concentrations, these chemicals controlled sprout regrowth in most species without unacceptable phytotoxicity. Using the air-powered, trunk injection system, field tests were conducted on 14 species in 12 states and 17 cities using MH and Atrinal. Both chemicals were successful in controlling growth of most species for one year. In several instances regrowth was controlled for two or more growing seasons. Investigations on the various factors that influence variability to chemical treatment indicate that environmental factors such as moisture stress, air pollution and deicing salts do not decrease the effectiveness of MH treatment and may, on occasion, enhance its growth control capabilities. Plant factors such as canopy size and developmental state at injection time also play an important role in determining the ultimate effectiveness of chemical treatment. Laboratory studies on transport and metabolism of MH show that the chemical is widely distributed throughout the plant over a 30 day period. Although most of the chemical is extractable, significant amounts were present in the bound form. MH may or may not be metabolized, depending on the species.

  19. General method to unravel ancient population structures through surnames, final validation on Italian data.

    PubMed

    Boattini, Alessio; Lisa, Antonella; Fiorani, Ornella; Zei, Gianna; Pettener, Davide; Manni, Franz

    2012-06-01

    We analyze the geographic location of 77,451 different Italian surnames (17,579,891 individuals) obtained from the lists of telephone subscribers of the year 1993. By using a specific neural network analysis (Self-Organizing Maps, SOMs), we automatically identify the geographic origin of 49,117 different surnames. To validate the methodology, we compare the results to a study, previously conducted, on the same database, with accurate supervised methods. By comparing the results, we find an overlap of 97%, meaning that the SOMs methodology is highly reliable and well traces back the geographic origin of surnames at the time of their introduction (Late Middle Ages/Renaissance in Italy). SOMs results enables one to distinguish monophyletic surnames from polyphyletic ones, that is surnames having had a single geographic and historic origin from those that started to be in use, with an identical spelling, in different locations (respectively, 76.06% and 21.05% of the total). As we are interested in geographic origins, polyphyletic surnames are excluded from further analyses. By comparing the present location of each monophyletic surname to its inferred geographic origin in late Middle Ages/Renaissance, we measure the extent of the migrations having occurred in Italy since that time. We find that the percentage of individuals presently living in the very area where their surname started to be in use centuries ago is extremely variable (ranging from 22.77% to 77.86% according to the province), thus meaning that self-assessed regional identities seldom correspond to the "autochthony" they imply. For example the upper part of the Thyrennian coast (Northern Latium, Tuscany) has a strong identity but few "autochthonous" inhabitants (∼28%) having been a passageway from the North to the South of Italy.

  20. Methods development for measuring and classifying flammability/combustibility of refrigerants. Final report

    SciTech Connect

    Heinonen, E.W.; Tapscott, R.E.; Crawford, F.R.

    1994-12-01

    Because of concerns for the effect that chlorofluorocarbon (CFC) fluids currently in use as refrigerants have on the environment, the refrigeration industry is considering the use of natural refrigerants, many of which are potentially flammable. In some cases, these flammable fluids may result in the least environmental damage when considering ozone depletion, global warming, efficiency, and photochemical reactivity. Many potentially flammable fluids have been proven to be effective when used either by themselves or as a part of a binary or ternary mixture. However, despite favorable initial test results, these fluids may not be acceptable to the general public if questions of safety cannot be adequately addressed. Significant research is being conducted to investigate the flammability of these materials. The purpose of this project is to experimentally determine the impact and variability of eleven different parameters which may affect flammability and/or combustibility of refrigerants and refrigerant blends, as a function of composition and test conditions, and to develop a better understanding of methods and conditions to measure the flammability of refrigerants. The refrigerants used in this study are being considered as new refrigerants and reviewed published data on these materials is scarce. The data contained herein should not be considered complete and should be used only to make relative comparisons of the impacts of the test parameters, not to represent the flammability characteristics of the materials. This report documents Task 3 of the test program. During Task 1, technical literature was thoroughly reviewed and a database of available documents was constructed. During Task 2, the test plan for this task was written. The goals of Task 3 are to investigate the flammability characteristics of selected blends of refrigerants R32, R134a, and R125 using an existing explosion sphere and a newly-constructed ASTM E681 apparatus.

  1. Measurement of the Top Quark Mass in Dilepton Final States with the Neutrino Weighting Method

    SciTech Connect

    Ilchenko, Yuriy

    2012-12-15

    The top quark is the heaviest fundamental particle observed to date. The mass of the top quark is a free parameter in the Standard Model (SM). A precise measurement of its mass is particularly important as it sets an indirect constraint on the mass of the Higgs boson. It is also a useful constraint on contributions from physics beyond the SM and may play a fundamental role in the electroweak symmetry breaking mechanism. I present a measurement of the top quark mass in the dilepton channel using the Neutrino Weighting Method. The data sample corresponds to an integrated luminosity of 4.3 fb-1 of p$\\bar{p}$ collisions at Tevatron with √s = 1.96 TeV, collected with the DØ detector. Kinematically under-constrained dilepton events are analyzed by integrating over neutrino rapidity. Weight distributions of t$\\bar{t}$ signal and background are produced as a function of the top quark mass for different top quark mass hypotheses. The measurement is performed by constructing templates from the moments of the weight distributions and input top quark mass, followed by a subsequent likelihood t to data. The dominant systematic uncertainties from jet energy calibration is reduced by using a correction from `+jets channel. To replicate the quark avor dependence of the jet response in data, jets in the simulated events are additionally corrected. The result is combined with our preceding measurement on 1 fb-1 and yields mt = 174.0± 2.4 (stat.) ±1.4 (syst.) GeV.

  2. Laserspray Ionization, a New Atmospheric Pressure MALDI Method for Producing Highly Charged Gas-phase Ions of Peptides and Proteins Directly from Solid Solutions*

    PubMed Central

    Trimpin, Sarah; Inutan, Ellen D.; Herath, Thushani N.; McEwen, Charles N.

    2010-01-01

    The first example of a matrix-assisted laser desorption/ionization (MALDI) process producing multiply charged mass spectra nearly identical to those observed with electrospray ionization (ESI) is presented. MALDI is noted for its ability to produce singly charged ions, but in the experiments described here multiply charged ions are produced by laser ablation of analyte incorporated into a common MALDI matrix, 2,5-dihydroxybenzoic acid, using standard solvent-based sample preparation protocols. Laser ablation is known to produce matrix clusters in MALDI provided a threshold energy is achieved. We propose that these clusters (liquid droplets) are highly charged, and under conditions that produce sufficient matrix evaporation, ions are field-evaporated from the droplets similarly to ESI. Because of the multiple charging, advanced mass spectrometers with limited mass-to-charge range can be used for protein characterization. Thus, using an Orbitrap mass spectrometer, low femtomole quantities of proteins produce full-range mass spectra at 100,000 mass resolution with <5-ppm mass accuracy and with 1-s acquisition. Furthermore, the first example of protein fragmentation using electron transfer dissociation with MALDI is presented. PMID:19955086

  3. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) coupled to XAD fractionation: Method to algal organic matter characterization.

    PubMed

    Nicolau, Rudy; Leloup, Maud; Lachassagne, Delphine; Pinault, Emilie; Feuillade-Cathalifaud, Geneviève

    2015-05-01

    This work is focused on the development of an analytical procedure for the improvement of the Organic Matter structure characterization, particularly the algal matter. Two fractions of algal organic matter from laboratory cultures of algae (Euglena gracilis) and cyanobacteria (Microcystis aeruginosa) were extracted with XAD resins. The fractions were studied using laser desorption ionization (LDI) and Matrix-Assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF). A comparison with the natural organic matter characteristics from commercial humic acids and fulvic acids extracted from Suwannee River was performed. Results show that algal and natural organic matters have unique quasi-polymeric structures. Significant repeating patterns were identified. Different fractions extracted from organic matter with common origin had common structures. Thus, 44, 114 and 169Da peaks separation for fractions from E. gracilis organic matter and 28, 58 and 100Da for M. aeruginosa ones were clearly observed. Using the developed protocol, a structural scheme and organic matter composition were obtained. The range 600-2000Da contained more architectural composition differences than the range 100-600Da, suggesting that organic matter is composed of an assembly of common small molecules. Associated to specific monomers, particular patterns were common to all samples but assembly and resulting structure were unique for each organic matter. Thus, XAD fractionation coupled to mass spectroscopy allowed determining a specific fingerprint for each organic matter.

  4. Laserspray ionization, a new atmospheric pressure MALDI method for producing highly charged gas-phase ions of peptides and proteins directly from solid solutions.

    PubMed

    Trimpin, Sarah; Inutan, Ellen D; Herath, Thushani N; McEwen, Charles N

    2010-02-01

    The first example of a matrix-assisted laser desorption/ionization (MALDI) process producing multiply charged mass spectra nearly identical to those observed with electrospray ionization (ESI) is presented. MALDI is noted for its ability to produce singly charged ions, but in the experiments described here multiply charged ions are produced by laser ablation of analyte incorporated into a common MALDI matrix, 2,5-dihydroxybenzoic acid, using standard solvent-based sample preparation protocols. Laser ablation is known to produce matrix clusters in MALDI provided a threshold energy is achieved. We propose that these clusters (liquid droplets) are highly charged, and under conditions that produce sufficient matrix evaporation, ions are field-evaporated from the droplets similarly to ESI. Because of the multiple charging, advanced mass spectrometers with limited mass-to-charge range can be used for protein characterization. Thus, using an Orbitrap mass spectrometer, low femtomole quantities of proteins produce full-range mass spectra at 100,000 mass resolution with <5-ppm mass accuracy and with 1-s acquisition. Furthermore, the first example of protein fragmentation using electron transfer dissociation with MALDI is presented.

  5. Atmospheric Ionization Measurements

    NASA Astrophysics Data System (ADS)

    Slack, Thomas; Mayes, Riley

    2015-04-01

    The measurement of atmospheric ionization is a largely unexplored science that potentially holds the key to better understanding many different geophysical phenomena through this new and valuable source of data. Through the LaACES program, which is funded by NASA through the Louisiana Space Consortium, students at Loyola University New Orleans have pursued the goal of measuring high altitude ionization for nearly three years, and were the first to successfully collect ionization data at altitudes over 30,000 feet using a scientific weather balloon flown from the NASA Columbia Scientific Ballooning Facility in Palestine, TX. In order to measure atmospheric ionization, the science team uses a lightweight and highly customized sensor known as a Gerdien condenser. Among other branches of science the data is already being used for, such as the study of aerosol pollution levels in the atmosphere, the data may also be useful in meteorology and seismology. Ionization data might provide another variable with which to predict weather or seismic activity more accurately and further in advance. Thomas Slack and Riley Mayes have served as project managers for the experiment, and have extensive knowledge of the experiment from the ground up. LaSPACE Louisiana Space Consortium.

  6. Final Technical Report for "Feature Extraction, Characterization, and Visualization for Protein Interaction via Geometric and Topological Methods"

    SciTech Connect

    Wang, Yusu

    2013-03-25

    Shape analysis plays an important role in many applications. In particular, in molecular biology, analyzing molecular shapes is essential to the fundamental problem of understanding how molecules interact. This project aims at developing efficient and effective algorithms to characterize and analyze molecular structures using geometric and topological methods. Two main components of this project are (1) developing novel molecular shape descriptors; and (2) identifying and representing meaningful features based on those descriptors. The project also produces accompanying (visualization) software. Results from this project (09/2006-10/2009) include the following publications. We have also set up web-servers for the software developed in this period, so that our new methods are accessible to a broader scientific community. The web sites are given below as well. In this final technical report, we first list publications and software resulted from this project. We then briefly explain the research conducted and main accomplishments during the period of this project.

  7. A sensitive liquid chromatography-electrospray ionization-mass spectrometry method for the simultaneous determination of pentoxyverine citrate and guaifenesin in human plasma---application to pharmacokinetic and bioequivalence studies.

    PubMed

    Wen, Jinhua; Zhang, Hong; Xia, Chunhua; Hu, Xiao; Xu, Wenwei; Cheng, Xiaohua; Gao, Jun; Xiong, Yuqing

    2010-04-01

    A sensitive and specific liquid chromatography-electrospray ionization-mass spectrometry method for the identification and quantification of pentoxyverine citrate and guaifenesin in human plasma has been developed. After extraction from plasma samples by ethyl acetate, the internal standard and analytes were separated by high-performance liquid chromatographic on a Shim-pack VP-ODS C(18) column (150 x 2.0 mm) using a mobile phase consisting of A (methanol) and B (0.4% glacial acetic acid and 4 mmol/L ammonium acetate) (A:B, 43 : 57). Analysis was performed on a Shimadzu LC/MS-2010A in selected ion monitoring mode with a positive electrospray ionization interface. The method was linear in the concentration range of 1.0-640.0 ng/mL for pentoxyverine citrate and 0.025-6.4 microg/mL for guaifenesin. The inter- and intra- precision were all within 12% and accuracy ranged from 85 to 115%.The lower limits of quantification were 1.0 ng/mL for pentoxyverine citrate and 25.0 ng/mL for guaifenesin. The extraction recovery was on average 81.95% for pentoxyverine citrate and 89.03% for guaifenesin. This is the first assay method reported for the simultaneous determination of pentoxyverine citrate and guaifenesin in plasma using one chromatographic run. Copyright (c) 2009 John Wiley & Sons, Ltd.

  8. A regression method including chronological and bone age for predicting final height in Turner's syndrome, with a comparison of existing methods.

    PubMed

    van Teunenbroek, A; Stijnen, T; Otten, B; de Muinck Keizer-Schrama, S; Naeraa, R W; Rongen-Westerlaken, C; Drop, S

    1996-04-01

    A total of 235 measurement points of 57 Dutch women with Turner's syndrome (TS), including women with spontaneous menarche and oestrogen treatment, served to develop a new Turner-specific final height (FH) prediction method (PTS). Analogous to the Tanner and Whitehouse mark 2 method (TW) for normal children, smoothed regression coefficients are tabulated for PTS for height (H), chronological age (CA) and bone age (BA), both TW RUS and Greulich and Pyle (GP). Comparison between all methods on 40 measurement points of 21 Danish TS women showed small mean prediction errors (predicted minus observed FH) and corresponding standard deviation (ESD) of both PTSRUS and PTSGP, in particular at the "younger" ages. Comparison between existing methods on the Dutch data indicated a tendency to overpredict FH. Before the CA of 9 years the mean prediction errors of the Bayley and Pinneau and TW methods were markedly higher compared with the other methods. Overall, the simplest methods--projected height (PAH) and its modification (mPAH)--were remarkably good at most ages. Although the validity of PTSRUS and PTSGP remains to be tested below the age of 6 years, both gave small mean prediction errors and a high accuracy. FH prediction in TS is important in the consideration of growth-promoting therapy or in the evaluation of its effects.

  9. Diagnosing transient ionization in dynamic events

    NASA Astrophysics Data System (ADS)

    Doyle, J. G.; Giunta, A.; Madjarska, M. S.; Summers, H.; O'Mullane, M.; Singh, A.

    2013-09-01

    Aims: The present study aims to provide a diagnostic line ratio that will enable the observer to determine whether a plasma is in a state of transient ionization. Methods: We use the Atomic Data and Analysis Structure (ADAS) to calculate line contribution functions for two lines, Si iv 1394 Å and O iv 1401 Å, formed in the solar transition region. The generalized collisional-radiative theory is used. It includes all radiative and electron collisional processes, except for photon-induced processes. State-resolved direct ionization and recombination to and from the next ionization stage are also taken into account. Results: For dynamic bursts with a decay time of a few seconds, the Si iv 1394 Å line can be enhanced by a factor of 2-4 in the first fraction of a second with the peak in the line contribution function occurring initially at a higher electron temperature due to transient ionization compared to ionization equilibrium conditions. On the other hand, the O iv 1401 Å does not show such any enhancement. Thus the ratio of these two lines, which can be observed with the Interface Region Imaging Spectrograph, can be used as a diagnostic of transient ionization. Conclusions: We show that simultaneous high-cadence observations of two lines formed in the solar transition region may be used as a direct diagnostic of whether the observed plasma is in transient ionization. The ratio of these two lines can change by a factor of four in a few seconds owing to transient ionization alone.

  10. DETECTORS AND EXPERIMENTAL METHODS: A comparison of ionizing radiation damage in CMOS devices from 60Co gamma rays, electrons and protons

    NASA Astrophysics Data System (ADS)

    He, Bao-Ping; Yao, Zhi-Bin; Zhang, Feng-Qi

    2009-06-01

    Radiation hardened CC4007RH and non-radiation hardened CC4011 devices were irradiated using 60Co gamma rays, 1 MeV electrons and 1-9 MeV protons to compare the ionizing radiation damage of the gamma rays with the charged particles. For all devices examined, with experimental uncertainty, the radiation induced threshold voltage shifts (ΔVth) generated by 60Co gamma rays are equal to that of 1 MeV electron and 1-7 MeV proton radiation under 0 gate bias condition. Under 5 V gate bias condition, the distinction of threshold voltage shifts (ΔVth) generated by 60Co gamma rays and 1 MeV electrons irradiation are not large, and the radiation damage for protons below 9 MeV is always less than that of 60Co gamma rays. The lower energy the proton has, the less serious the radiation damage becomes.

  11. Dating the Martian meteorite Zagami by the ⁸⁷Rb-⁸⁷Sr isochron method with a prototype in situ resonance ionization mass spectrometer.

    PubMed

    Anderson, F Scott; Levine, Jonathan; Whitaker, Tom J

    2015-01-30

    The geologic history of the Solar System builds on an extensive record of impact flux models, crater counts, and ~270 kg of lunar samples analyzed in terrestrial laboratories. However, estimates of impactor flux may be biased by the fact that most of the dated Apollo samples were only tenuously connected to an assumed geologic context. Moreover, uncertainties in the modeled cratering rates are significant enough to lead to estimated errors for dates on Mars and the Moon of ~1 Ga. Given the great cost of sample return missions, combined with the need to sample multiple terrains on multiple planets, we have developed a prototype instrument that can be used for in situ dating to better constrain the age of planetary samples. We demonstrate the first use of laser ablation resonance ionization mass spectrometry for (87)Rb-(87)Sr isochron dating of geological specimens. The demands of accuracy and precision have required us to meet challenges including regulation of the ambient temperature, measurement of appropriate backgrounds, sufficient ablation laser intensity, avoidance of the defocusing effect of the plasma created by ablation pulses, and shielding of our detector from atoms and ions of other elements. To test whether we could meaningfully date planetary materials, we have analyzed a piece of the Martian meteorite Zagami. In each of four separate measurements we obtained (87)Rb-(87)Sr isochron ages for Zagami consistent with its published age, and, in both of two measurements that reached completion, we obtained better than 200 Ma precision. Combining all our data into a single isochron with 581 spot analyses gives an (87)Rb-(87)Sr age for this specimen of 360 ±90 Ma. Our analyses of the Zagami meteorite represent the first successful application of resonance ionization mass spectrometry to isochron geochronology. Furthermore, the technique is miniaturizable for spaceflight and in situ dating on other planetary bodies. © 2014 The Authors. Rapid Communications in

  12. Atmospheric Pressure Ionization Using a High Voltage Target Compared to Electrospray Ionization

    NASA Astrophysics Data System (ADS)

    Lubin, Arnaud; Bajic, Steve; Cabooter, Deirdre; Augustijns, Patrick; Cuyckens, Filip

    2017-02-01

    A new atmospheric pressure ionization (API) source, viz. UniSpray, was evaluated for mass spectrometry (MS) analysis of pharmaceutical compounds by head-to-head comparison with electrospray ionization (ESI) on the same high-resolution MS system. The atmospheric pressure ionization source is composed of a grounded nebulizer spraying onto a high voltage, cylindrical stainless steel target. Molecules are ionized in a similar fashion to electrospray ionization, predominantly producing protonated or deprotonated species. Adduct formation (e.g., proton and sodium adducts) and in-source fragmentation is shown to be almost identical between the two sources. The performance of the new API source was compared with electrospray by infusion of a mix of 22 pharmaceutical compounds with a wide variety of functional groups and physico-chemical properties (molecular weight, logP, and pKa) in more than 100 different conditions (mobile phase strength, solvents, pH, and flow rate). The new API source shows an intensity gain of a factor 2.2 compared with ESI considering all conditions on all compounds tested. Finally, some hypotheses on the ionization mechanism, similarities, and differences with ESI, are discussed.

  13. Electron Impact Ionization of He atom using screening potential

    NASA Astrophysics Data System (ADS)

    Saha, Hari P.

    2012-06-01

    We will report the results of our investigation on electron impact ionization of helium atom using our extended MCHF method [1] for electron impact ionization of atoms. The initial state wave function will be calculated with both HF and MCHF approximations and the electron correlation between the two final state continuum electrons will be obtained using the screening potential [2-4]. Calculations will be made for triple differential cross sections for 4 eV excess energy sharing equally by the two final state continuum electrons. The results will be presented for all scattering angles and all kinematics. Comparison will be made with available experimental and theoretical data. [4pt] [1] Hari P. Saha, Phys. Rev. A82, 042703 (2010); J.Phys. B44, 065202 (2011).[0pt] [2] M.R.H. Rudge and M.J. Seaton, Proc. Roy. Soc. A293. 262 (1965).[0pt] [3] M.R.H. Rudge, Rev. Mod. Phys. 40, 564 (1968).[0pt] [4] C.Pan and A.F Starace, Phys. Rev. Lett. 67, 185 (1991); Phys. Rev. A45, 4588 (1992).

  14. Evaluation of a matrix-assisted laser desorption ionization-time of flight mass spectrometry assisted, selective broth method to screen for vancomycin-resistant enterococci in patients at high risk

    PubMed Central

    Huang, Tsi-Shu; Lee, Susan Shin-Jung; Lee, Chia-Chien; Chen, Chiu-Yen; Chen, Fang-Chen; Chen, Bao-Chen; Sy, Cheng Len

    2017-01-01

    Background Bile esculin azide with vancomycin (BEAV) medium is a sensitive, but slightly less specific method for vancomycin-resistant enterococci (VRE) screening. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a rapid method for identification of clinical pathogens. This study aimed to assess the performance of a novel combination screening test for VRE, using BEAV broth combined with MALDI-TOF MS. Materials and methods Clinical specimens were collected from patients at risk of VRE carriage, and tested by the novel combination method, using selective BEAV broth culture method followed by MALDI-TOF MS identification (SBEAVM). The reference method used for comparison was the ChromID VRE agar method. Results A total of 135 specimens were collected from 78 patients, and 63 specimens tested positive for VRE positive using the ChromID VRE method (positive rate 46.7%). The sensitivity, specificity, positive predictive value, and negative predictive value of SBEAVM method after an incubation period of 28 hours were 93.7%, 90.3%, 89.4%, and 94.2%, respectively. The SBEAVM method when compared to the ChromID VRE method had a shorter turnaround time (29 vs. 48–72 hours) and lower laboratory cost ($2.11 vs. $3.23 per test). Conclusions This study demonstrates that SBEAVM is a rapid, inexpensive, and accurate method for use in VRE screening. PMID:28609453

  15. Partial Fourier-transform approach to tunnel ionization: Atomic systems

    SciTech Connect

    Murray, Ryan; Liu, Wing-Ki; Ivanov, Misha Yu.

    2010-02-15

    We present physically transparent and computationally simple method for calculating tunnel ionization rates for arbitrary bound states and arbitrary potentials in three dimensions. Here, we verify applicability of the method analytically by demonstrating that it reproduces all known analytical results for tunnel ionization from arbitrary atomic states in a single-center Coulomb potential in the presence of a constant electric field.

  16. A validation of a simple model for the calculation of the ionization energies in X-ray laser-cluster interactions

    SciTech Connect

    White, Jeff; Ackad, Edward

    2015-02-15

    The outer-ionization of an electron from a cluster is an unambiguous quantity, while the inner-ionization threshold is not, resulting in different microscopic quantum-classical hybrid models used in laser-cluster interactions. A simple local ionization threshold model for the change in the ionization energy is proposed and examined, for atoms and ions, at distances in between the initial configuration of the cluster to well into the cluster's disintegration. This model is compared with a full Hartree-Fock energy calculation which accounts for the electron correlation effects using the coupled cluster method with single and double excitations with perturbative triples (CCSD(T)). Good agreement is found between the two lending a strong theoretical support to works which rely on such models for the final and transient properties of the laser-cluster interaction.

  17. A qualitative and quantitative laser-based computer-aided flow visualization method. M.S. Thesis, 1992 Final Report

    NASA Technical Reports Server (NTRS)

    Canacci, Victor A.; Braun, M. Jack

    1994-01-01

    The experimental approach presented here offers a nonintrusive, qualitative and quantitative evaluation of full field flow patterns applicable in various geometries in a variety of fluids. This Full Flow Field Tracking (FFFT) Particle Image Velocimetry (PIV) technique, by means of particle tracers illuminated by a laser light sheet, offers an alternative to Laser Doppler Velocimetry (LDV), and intrusive systems such as Hot Wire/Film Anemometry. The method makes obtainable the flow patterns, and allows quantitative determination of the velocities, accelerations, and mass flows of an entire flow field. The method uses a computer based digitizing system attached through an imaging board to a low luminosity camera. A customized optical train allows the system to become a long distance microscope (LDM), allowing magnifications of areas of interest ranging up to 100 times. Presented in addition to the method itself, are studies in which the flow patterns and velocities were observed and evaluated in three distinct geometries, with three different working fluids. The first study involved pressure and flow analysis of a brush seal in oil. The next application involved studying the velocity and flow patterns in a cowl lip cooling passage of an air breathing aircraft engine using water as the working fluid. Finally, the method was extended to a study in air to examine the flows in a staggered pin arrangement located on one side of a branched duct.

  18. XUV ionization of aligned molecules

    SciTech Connect

    Kelkensberg, F.; Siu, W.; Gademann, G.; Rouzee, A.; Vrakking, M. J. J.; Johnsson, P.; Lucchini, M.; Lucchese, R. R.

    2011-11-15

    New extreme-ultraviolet (XUV) light sources such as high-order-harmonic generation (HHG) and free-electron lasers (FELs), combined with laser-induced alignment techniques, enable novel methods for making molecular movies based on measuring molecular frame photoelectron angular distributions. Experiments are presented where CO{sub 2} molecules were impulsively aligned using a near-infrared laser and ionized using femtosecond XUV pulses obtained by HHG. Measured electron angular distributions reveal contributions from four orbitals and the onset of the influence of the molecular structure.

  19. COMPARISON OF INAA AND RNAA METHODS WITH THERMAL-IONIZATION MASS SPECTROMETRY FOR IRIDIUM DETERMINATIONS IN ATMOSPHERIC TRACER STUDIES. (R825247)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  20. COMPARISON OF INAA AND RNAA METHODS WITH THERMAL-IONIZATION MASS SPECTROMETRY FOR IRIDIUM DETERMINATIONS IN ATMOSPHERIC TRACER STUDIES. (R825247)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  1. Method development for the analysis of N-nitrosodimethylamine and other N-nitrosamines in drinking water at low nanogram/liter concentrations using solid-phase extraction and gas chromatography with chemical ionization tandem mass spectrometry.

    PubMed

    Munch, Jean W; Bassett, Margarita V

    2006-01-01

    N-nitrosodimethylamine (NDMA) is a probable human carcinogen of concern that has been identified as a drinking water contaminant. U.S. Environmental Protection Agency Method 521 has been developed for the analysis of NDMA and 6 additional N-nitrosamines in drinking water at low ng/L concentrations. The method uses solid-phase extraction with coconut charcoal as the sorbent and dichloromethane as the eluent to concentrate 0.50 L water samples to 1 mL. The extracts are analyzed by gas chromatography-chemical ionization tandem mass spectrometry using large-volume injection. Method performance was evaluated in 2 laboratories. Typical analyte recoveries of 87-104% were demonstrated for fortified reagent water samples, and recoveries of 77-106% were demonstrated for fortified drinking water samples. All relative standard deviations on replicate analyses were < 11%.

  2. Development of a Rapid and Accurate Identification Method for Citrobacter Species Isolated from Pork Products Using a Matrix-Assisted Laser-Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS).

    PubMed

    Kwak, Hye-Lim; Han, Sun-Kyung; Park, Sunghoon; Park, Si Hong; Shim, Jae-Yong; Oh, Mihwa; Ricke, Steven C; Kim, Hae-Yeong

    2015-09-01

    Previous detection methods for Citrobacter are considered time consuming and laborious. In this study, we have developed a rapid and accurate detection method for Citrobacter species in pork products, using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). A total of 35 Citrobacter strains were isolated from 30 pork products and identified by both MALDI-TOF MS and 16S rRNA gene sequencing approaches. All isolates were identified to the species level by the MALDI-TOF MS, while 16S rRNA gene sequencing results could not discriminate them clearly. These results confirmed that MALDI-TOF MS is a more accurate and rapid detection method for the identification of Citrobacter species.

  3. An innovative method based on quick, easy, cheap, effective, rugged, and safe extraction coupled to desorption electrospray ionization-high resolution mass spectrometry for screening the presence of paralytic shellfish toxins in clams.

    PubMed

    Mattarozzi, Monica; Bianchi, Federica; Milioli, Marco; Cavazza, Antonella; Careri, Maria

    2016-01-15

    The capabilities of desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) were tested for screening the presence of some paralytic shellfish toxins in clams. A quick, easy, cheap, effective, rugged, and safe (QuEChERS) approach is proposed for sample clean-up. QuEChERS extraction was optimized by using a full factorial design followed by the multicriteria method of the desirability functions. Quantitation limits in the microgram per kilogram range proved reliability of the method for the detection of the investigated toxins in accordance to the rules laid down by European legislation. The optimized QuEChERS-DESI-HRMS based-method allowed for a rapid reliable screening of the investigated compounds at levels of interest, thus being useful for high-throughput analyses.

  4. Radar detection of radiation-induced ionization in air

    DOEpatents

    Gopalsami, Nachappa; Heifetz, Alexander; Chien, Hual-Te; Liao, Shaolin; Koehl, Eugene R.; Raptis, Apostolos C.

    2015-07-21

    A millimeter wave measurement system has been developed for remote detection of airborne nuclear radiation, based on electromagnetic scattering from radiation-induced ionization in air. Specifically, methods of monitoring radiation-induced ionization of air have been investigated, and the ionized air has been identified as a source of millimeter wave radar reflection, which can be utilized to determine the size and strength of a radiation source.

  5. Ionizing radiation and life.

    PubMed

    Dartnell, Lewis R

    2011-01-01

    Ionizing radiation is a ubiquitous feature of the Cosmos, from exogenous cosmic rays (CR) to the intrinsic mineral radioactivity of a habitable world, and its influences on the emergence and persistence of life are wide-ranging and profound. Much attention has already been focused on the deleterious effects of ionizing radiation on organisms and the complex molecules of life, but ionizing radiation also performs many crucial functions in the generation of habitable planetary environments and the origins of life. This review surveys the role of CR and mineral radioactivity in star formation, generation of biogenic elements, and the synthesis of organic molecules and driving of prebiotic chemistry. Another major theme is the multiple layers of shielding of planetary surfaces from the flux of cosmic radiation and the various effects on a biosphere of violent but rare astrophysical events such as supernovae and gamma-ray bursts. The influences of CR can also be duplicitous, such as limiting the survival of surface life on Mars while potentially supporting a subsurface biosphere in the ocean of Europa. This review highlights the common thread that ionizing radiation forms between the disparate component disciplines of astrobiology. © Mary Ann Liebert, Inc.

  6. Microchip sonic spray ionization.

    PubMed

    Pól, Jaroslav; Kauppila, Tiina J; Haapala, Markus; Saarela, Ville; Franssila, Sami; Ketola, Raimo A; Kotiaho, Tapio; Kostiainen, Risto

    2007-05-01

    The first microchip version of sonic spray ionization (SSI) as an atmospheric pressure ionization source for mass spectrometry (MS) is presented. The microchip used for SSI has recently been developed in our laboratory, and it has been used before as an atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) source. Now the ionization is achieved simply by applying high (sonic) speed nebulizer gas, without heat, corona discharge, or high voltage. The microchip SSI was applied to the analysis of tetra-N-butylammonium, verapamil, testosterone, angiotensin I, and ibuprofen. The limits of detection were in the range of 15 nM to 4 microM. The technique was found to be highly dependent on the position of the chip toward the mass spectrometer inlet, and on the gas and the sample solution flow rates. The microchip SSI provided dynamic linearity following a pattern similar to that used with electrospray, good quantitative repeatability (RSD=16%), and long-term signal stability.

  7. Ionizing radiation from tobacco

    SciTech Connect

    Westin, J.B.

    1987-04-24

    Accidents at nuclear power facilities seem inevitably to bring in their wake a great deal of concern on the part of both the lay and medical communities. Relatively little attention, however, is given to what may be the largest single worldwide source of effectively carcinogenic ionizing radiation: tobacco. The risk of cancer deaths from the Chernobyl disaster are tobacco smoke is discussed.

  8. Alkali ionization detector

    DOEpatents

    Hrizo, John; Bauerle, James E.; Witkowski, Robert E.

    1982-01-01

    A calibration filament containing a sodium-bearing compound is included in combination with the sensing filament and ion collector plate of a sodium ionization detector to permit periodic generation of sodium atoms for the in-situ calibration of the detector.

  9. Practical method for determination of air kerma by use of an ionization chamber toward construction of a secondary X-ray field to be used in clinical examination rooms.

    PubMed

    Maehata, Itsumi; Hayashi, Hiroaki; Kimoto, Natsumi; Takegami, Kazuki; Okino, Hiroki; Kanazawa, Yuki; Tominaga, Masahide

    2016-07-01

    We propose a new practical method for the construction of an accurate secondary X-ray field using medical diagnostic X-ray equipment. For accurate measurement of the air kerma of an X-ray field, it is important to reduce and evaluate the contamination rate of scattered X-rays. To determine the rate quantitatively, we performed the following studies. First, we developed a shield box in which an ionization chamber could be set at an inner of the box to prevent detection of the X-rays scattered from the air. In addition, we made collimator plates which were placed near the X-ray source for estimation of the contamination rate by scattered X-rays from the movable diaphragm which is a component of the X-ray equipment. Then, we measured the exposure dose while changing the collimator plates, which had diameters of 25-90 mm(ϕ). The ideal value of the exposure dose was derived mathematically by extrapolation to 0 mm(ϕ). Tube voltages ranged from 40 to 130 kV. Under these irradiation conditions, we analyzed the contamination rate by the scattered X-rays. We found that the contamination rates were less than 1.7 and 2.3 %, caused by air and the movable diaphragm, respectively. The extrapolated value of the exposure dose has been determined to have an uncertainty of 0.7 %. The ionization chamber used in this study was calibrated with an accuracy of 5 %. Using this kind of ionization chamber, we can construct a secondary X-ray field with an uncertainty of 5 %.

  10. Modulated voltage metastable ionization detector

    NASA Technical Reports Server (NTRS)

    Carle, G. C.; Kojiro, D. R.; Humphrey, D. E. (Inventor)

    1985-01-01

    The output current from a metastable ionization detector (MID) is applied to a modulation voltage circuit. An adjustment is made to balance out the background current, and an output current, above background, is applied to an input of a strip chart recorder. For low level concentrations, i.e., low detected output current, the ionization potential will be at a maximum and the metastable ionization detector will operate at its most sensitive level. When the detected current from the metastable ionization detector increases above a predetermined threshold level, a voltage control circuit is activated which turns on a high voltage transistor which acts to reduce the ionization potential. The ionization potential applied to the metastable ionization detector is then varied so as to maintain the detected signal level constant. The variation in ionization potential is now related to the concentration of the constituent and a representative amplitude is applied to another input of said strip chart recorder.

  11. Ionization Suppression and Recovery in Direct Biofluid Analysis Using Paper Spray Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Vega, Carolina; Spence, Corina; Zhang, Chengsen; Bills, Brandon J.; Manicke, Nicholas E.

    2016-04-01

    Paper spray mass spectrometry is a method for the direct analysis of biofluid samples in which extraction of analytes from dried biofluid spots and electrospray ionization occur from the paper on which the dried sample is stored. We examined matrix effects in the analysis of small molecule drugs from urine, plasma, and whole blood. The general method was to spike stable isotope labeled analogs of each analyte into the spray solvent, while the analyte itself was in the dried biofluid. Intensity of the labeled analog is proportional to ionization efficiency, whereas the ratio of the analyte intensity to the labeled analog in the spray solvent is proportional to recovery. Ion suppression and recovery were found to be compound- and matrix-dependent. Highest levels of ion suppression were obtained for poor ionizers (e.g., analytes lacking basic aliphatic amine groups) in urine and approached -90%. Ion suppression was much lower or even absent for good ionizers (analytes with aliphatic amines) in dried blood spots. Recovery was generally highest in urine and lowest in blood. We also examined the effect of two experimental parameters on ion suppression and recovery: the spray solvent and the sample position (how far away from the paper tip the dried sample was spotted). Finally, the change in ion suppression and analyte elution as a function of time was examined by carrying out a paper spray analysis of dried plasma spots for 5 min by continually replenishing the spray solvent.

  12. Ionization Suppression and Recovery in Direct Biofluid Analysis Using Paper Spray Mass Spectrometry.

    PubMed

    Vega, Carolina; Spence, Corina; Zhang, Chengsen; Bills, Brandon J; Manicke, Nicholas E

    2016-04-01

    Paper spray mass spectrometry is a method for the direct analysis of biofluid samples in which extraction of analytes from dried biofluid spots and electrospray ionization occur from the paper on which the dried sample is stored. We examined matrix effects in the analysis of small molecule drugs from urine, plasma, and whole blood. The general method was to spike stable isotope labeled analogs of each analyte into the spray solvent, while the analyte itself was in the dried biofluid. Intensity of the labeled analog is proportional to ionization efficiency, whereas the ratio of the analyte intensity to the labeled analog in the spray solvent is proportional to recovery. Ion suppression and recovery were found to be compound- and matrix-dependent. Highest levels of ion suppression were obtained for poor ionizers (e.g., analytes lacking basic aliphatic amine groups) in urine and approached -90%. Ion suppression was much lower or even absent for good ionizers (analytes with aliphatic amines) in dried blood spots. Recovery was generally highest in urine and lowest in blood. We also examined the effect of two experimental parameters on ion suppression and recovery: the spray solvent and the sample position (how far away from the paper tip the dried sample was spotted). Finally, the change in ion suppression and analyte elution as a function of time was examined by carrying out a paper spray analysis of dried plasma spots for 5 min by continually replenishing the spray solvent. Graphical Abstract ᅟ.

  13. A gas chromatographic-positive ion chemical ionization-mass spectrometric method for the determination of I-alpha-acetylmethadol (LAAM), norLAAM, and dinorLAAM in plasma, urine, and tissue.

    PubMed

    Moody, D E; Crouch, D J; Sakashita, C O; Alburges, M E; Minear, K; Schulthies, J E; Foltz, R L

    1995-10-01

    l-alpha-Acetylmethadol (LAAM) is approved as a substitute for methadone for the treatment of opiate addiction. Analytical methods are needed to quantitate LAAM and its two psychoactive metabolites, norLAAM and dinorLAAM, to support pharmacokinetic and other studies. We developed a gas chromatographic-positive ion chemical ionization-mass spectrometric method for these analyses. The method uses 0.5 mL urine or 1.0 mL plasma or tissue homogenate, deuterated (d3) isotopomers as internal standards, methanolic denaturation of protein (for plasma and tissue), and extraction of the buffered sample with n-butyl chloride. For tissue homogenates, an acidic back extraction is included. norLAAM and dinorLAAM were derivatized with trifluoroacetic anhydride. Chromatographic separation of LAAM and derivatized norLAAM and dinorLAAM is achieved with a 5% phenyl methylsilicone capillary column. Positive ion chemical ionization detection using methane-ammonia as the reagent gas produces abundant protonated ions (MH+) for LAAM (m/z 354) and LAAM-d3 (m/z 357) and ammonia adduct ions (MNH4+) for the derivatized norLAAM (m/z 453), norLAAM-d3 (m/z 45 6), dinorLAAM (m/z 439), and dinorLAAM-d3 (m/z 442). The linear range of the calibration curves were matrix dependent: 5-300 ng/mL for plasma, 10-1000 ng/mL for urine, and 10-600 ng/g for tissue homogenates. The low calibrator was the validated limit of quantitation for that matrix. The method is precise and accurate with percent coefficients of variation and percent of targets within 13%. The method was applied to the analysis of human urine and plasma samples; rat plasma, liver, and brain samples; and human liver microsomes following incubation with LAAM.

  14. A mechanism for ionization of nonvolatile compounds in mass spectrometry: considerations from MALDI and inlet ionization.

    PubMed

    Trimpin, Sarah; Wang, Beixi; Inutan, Ellen D; Li, Jing; Lietz, Christopher B; Harron, Andrew; Pagnotti, Vincent S; Sardelis, Diana; McEwen, Charles N

    2012-10-01

    Mechanistic arguments relative to matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) address observations that predominately singly charged ions are detected. However, recently a matrix assisted laser ablation method, laserspray ionization (LSI), was introduced that can use the same sample preparation and laser as MALDI, but produce highly charged ions from proteins. In MALDI, ions are generated from neutral molecules by the photon energy provided to a matrix, while in LSI ions are produced inside a heated inlet tube linking atmospheric pressure and the first vacuum region of the mass spectrometer. Some LSI matrices also produce highly charged ions with MALDI ion sources operated at intermediate pressure or high vacuum. The operational similarity of LSI to MALDI, and the large difference in charge states observed by these methods, provides information of fundamental importance to proposed ionization mechanisms for LSI and MALDI. Here, we present data suggesting that the prompt and delayed ionization reported for vacuum MALDI are both fast processes relative to producing highly charged ions by LSI. The energy supplied to produce these charged clusters/droplets as well as their size and time available for desolvation are determining factors in the charge states of the ions observed. Further, charged droplets/clusters may be a common link for ionization of nonvolatile compounds by a variety of MS ionization methods, including MALDI and LSI.

  15. Dynamics of cluster dissociation following multiphoton ionization

    SciTech Connect

    Castleman, A.W.

    1986-01-01

    A major advance in the study of unimolecular dissociation and the spectroscopy of clusters has become available through the use of multiphoton ionization coupled with a reflectron introduced into the drift region of a time-of-flight mass spectrometer. Using single and two-color tunable pulsed lasers, the excess energy introduced into a cluster can be well controlled. The power of this method is demonstrated by the results of recent investigations of hydrogen-bonded clusters which, following ionization, lead to an internal ion-molecule reaction, and cluster fragmentation. The role of dissociation and the influence of the thermochemical stability of cluster ions in effecting the appearance of magic numbers in certain cluster distributions is discussed. The application of this method in determining ionization potentials of probe molecules following successive clustering with a solvent species is also presented.

  16. Theoretical determinations of ionization potentials of dopamine

    NASA Astrophysics Data System (ADS)

    Lu, J. F.; Yu, Z. Y.

    2013-04-01

    Adiabatic and vertical ionization potentials (IPs) of nine conformers of dopamine in the gas phase are determined using density functional theory (DFT) B3LYP, B3P86, B3PW91 methods and high level ab initio HF method with 6-311++G** basis set, respectively. And the nine stable cationic states have been found in the ionization process of dopamine. Vertical ionization potentials of nine conformers of dopamine are calculated using the older outer-valence Green's function (OVGF) calculations at 6-311++G** basis set. Vibrational frequencies and infrared spectrum intensities of G1b and G1b+ at B3LYP/6-311++G** level are discussed.

  17. Fabrication of the prototype 201.25 mhz cavity for a muon ionization cooling experiment

    SciTech Connect

    Rimmer, R.A.; Manning, S.; Manus, R.; Phillips, L.; Stirbet, M.; Worland, K.; Wu, G.; Li, D.; MacGill, R.; Staples, J.; Virostek, S.; Zisman, M.S.; Taminger, K.; Hafley, R.; Martin, R.; Summers, D.; Reep, M.

    2005-05-20

    We describe the fabrication and assembly of the first prototype 201. 25 MHz copper cavity for the muon ionization cooling experiment (MICE). This cavity was developed by the US MUCOOL collaboration and will be tested in the new MUCOOL Test Area at Fermilab. We outline the component and subassembly fabrication steps and the various metal forming and joining methods used to produce the final cavity shape. These include spinning, brazing, TIG welding, electron beam welding, electron beam annealing and deep drawing. Some of the methods developed for this cavity are novel and offer significant cost savings over conventional methods.

  18. Fabrication of the Prototype 201.25 MHz Cavity for a Muon Ionization Cooling Experiment

    SciTech Connect

    R.A. Rimmer; S. Manning; R. Manus; L. Phillips; M. Stirbet; K. Worland; G. Wu; D. Li; R. MacGill; J. Staples; S. Virostek; M. Zisman; K. Taminger; R. Hafley; R. Martin; D. Summers; M. Reep

    2005-05-01

    We describe the fabrication and assembly of the first prototype 201.25 MHz copper cavity for the muon ionization cooling experiment (MICE). This cavity was developed by the US MUCOOL collaboration and will be tested in the new MUCOOL Test Area at Fermilab. We outline the component and subassembly fabrication steps and the various metal forming and joining methods used to produce the final cavity shape. These include spinning, brazing, TIG welding, electron beam welding, electron beam annealing and deep drawing. Some of the methods developed for this cavity are novel and offer significant cost savings over conventional construction methods.

  19. A novel ultrasound-assisted back extraction reverse micelles method coupled with gas chromatography-flame ionization detection for determination of aldehydes in heated edibles oils.

    PubMed

    Ramezani, Zahra; Mirzajani, Roya; Kardani, Fatemeh

    2015-12-01

    A novel ultrasound-assisted back extraction reverse micelles coupled with gas chromatography-flame ionization detection has been developed for the extraction and determination of some short chain aldehydes in different heated edible oil samples. After the homogenization of the oil samples with Triton X-100, 200 μL of methanol was added to facilitate the phase separation. The aqueous micelle phase has been separated by centrifugation, then it was treated with a mixture of H2O: CHCl3 and ultrasonic vibration, were used to effectively back-extraction of the analytes into the chloroform phase. The sedimented organic phase was obtained after centrifugation, withdrawn into the microsyringe and directly injected into the GC-FID system. The calibration graphs were linear in the range 0.05-20 mg L(-1). The limits of detection were in the range of 0.02-0.15 mg L(-1). This procedure was successfully applied for determination of propanal, butanal, hexanal and heptanal in real heated oil samples.

  20. Development and validation of a liquid chromatography-electrospray ionization-time-of-flight mass spectrometry method for induced changes in Nicotiana attenuata leaves during simulated herbivory.

    PubMed

    Gaquerel, Emmanuel; Heiling, Sven; Schoettner, Matthias; Zurek, Gabriela; Baldwin, Ian T

    2010-09-08

    A liquid chromatography-electrospray ionization-time-of-flight mass spectrometry (HPLC/ESI-TOF-MS) procedure was developed to characterize changes induced in Nicotiana attenuata leaves 1 h and 5 days after wounding and application of Manduca sexta elicitors. The constancy of the measurement conditions was first confirmed for 22 selected analytes spanning the entire chromatogram. Using the Profile Analysis software, we extracted 367 buckets, which were analyzed by principal component analysis and two-factorial ANOVA. One hundred seventy-three buckets were found to be statistically regulated, 128 due to time effects, and 85 due to treatment effects. In vivo 15N-isotope labeling was used to facilitate the annotation and the interpretation of the fragmentation pattern of nitrogen-containing metabolites, and a correlation analysis was performed to test mathematical relationships existing among potential in-source fragments. Additionally, tandem MS measurements of the most regulated ions are presented. Altogether, this study defines a framework for the mining and annotation of major herbivory-elicited changes in Nicotiana attenuata.

  1. Characterisation of "caramel-type" thermal decomposition products of selected monosaccharides including fructose, mannose, galactose, arabinose and ribose by advanced electrospray ionization mass spectrometry methods.

    PubMed

    Golon, Agnieszka; Kuhnert, Nikolai

    2013-07-01

    The chemical analysis of caramel, formed upon heating of carbohydrates, remains a significant challenge due to the complexity of the resulting product mixture. Identification of the products formed upon heating of monosaccharides including fructose, mannose, galactose, arabinose and ribose is essential to understand the composition and properties of carbohydrate-rich processed foods. In this work, we report on the use of combined mass spectrometry techniques, including high performance liquid chromatography and electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)). The composition of the obtained caramel was examined by high resolution mass spectrometry along with van Krevelen and Kendrick analysis. We found that caramel is composed of oligomers with up to six carbohydrate units formed through unselective glycosidic bond formation, their dehydrated products by losing up to eight water molecules, hydrated products and disproportionation products. An accurate mass measurement and subsequent fragment ion studies of all caramel samples (around 40 compounds) can thus be identified. Glycosidic bond and ring cleavages of sugar moieties were the major observable fragmentation pathways during this experiment. The innovative analytical strategies for the complex mixture analysis used provide a comprehensive account of the chemical composition of caramel, one of the most popular dietary materials over the world.

  2. Comments on ionization cooling channels

    DOE PAGES

    Neuffer, David

    2017-09-25

    Ionization cooling channels with a wide variety of characteristics and cooling properties are being developed. These channels can produce cooling performances that are largely consistent with the linear ionization cooling theory developed previously. In this study, we review ionization cooling theory, discuss its application to presently developing cooling channels, and discuss criteria for optimizing cooling.

  3. Comments on ionization cooling channels

    NASA Astrophysics Data System (ADS)

    Neuffer, D.

    2017-09-01

    Ionization cooling channels with a wide variety of characteristics and cooling properties are being developed. These channels can produce cooling performances that are largely consistent with the linear ionization cooling theory developed previously. In this paper we review ionization cooling theory, discuss its application to presently developing cooling channels, and discuss criteria for optimizing cooling.

  4. Epicyclic helical channels for parametric resonance ionization cooling

    SciTech Connect

    Johson, Rolland Paul; Derbenev, Yaroslav

    2015-08-23

    Proposed next-generation muon colliders will require major technical advances to achieve rapid muon beam cooling requirements. Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. In PIC, a half-integer parametric resonance causes strong focusing of a muon beam at appropriately placed energy absorbers while ionization cooling limits the beam’s angular spread. Combining muon ionization cooling with parametric resonant dynamics in this way should then allow much smaller final transverse muon beam sizes than conventional ionization cooling alone. One of the PIC challenges is compensation of beam aberrations over a sufficiently wide parameter range while maintaining the dynamical stability with correlated behavior of the horizontal and vertical betatron motion and dispersion. We explore use of a coupling resonance to reduce the dimensionality of the problem and to shift the dynamics away from non-linear resonances. PIC simulations are presented.

  5. Effect of ionizing radiation on polyaniline solutions

    NASA Astrophysics Data System (ADS)

    Wolszczak, M.; Kroh, J.; Abdel-Hamid, M. M.

    1996-06-01

    This communication presents the optical studies associated with transition doped (metallic)-neutral (semiconductor or insulator) state for conducting polymers. Special attention is focused on the electronic properties of polyaniline. The interconversion of different oxidation states of polyanilines has been studied by chemical and radiolytic methods. The polyaniline system is described by three sets of chromophores of three different oxidation states: fully reduced leucoemeraldine base (LB), partially oxidized emeraldine base (EB), and fully oxidized pernigraniline (PB). Each oxidation state can exist in its protonated form by treatment with an acid. All members of polyaniline family are spectroscopically distinguishable. The radiolytic study presents evidence that the polyaniline can exist in a continuum of oxidation states. The highly conducting form of polymer, i.e. emeraldine salt can be converted by using ionizing radiation into leucoemeraldine salt. The leucoemeraldine base is the final product of radiolysis of emeraldine base solution. The fully oxidized form of polyaniline can also be obtained by the irradiation of EB in the presence of CCl 4 or chlorobenzene.

  6. Electron impact ionization of the gas-phase sorbitol

    NASA Astrophysics Data System (ADS)

    Chernyshova, Irina; Markush, Pavlo; Zavilopulo, Anatoly; Shpenik, Otto

    2015-03-01

    Ionization and dissociative ionization of the sorbitol molecule by electron impact have been studied using two different experimental methods. In the mass range of m/ z = 10-190, the mass spectra of sorbitol were recorded at the ionizing electron energies of 70 and 30 eV. The ion yield curves for the fragment ions have been analyzed and the appearance energies of these ions have been determined. The relative total ionization cross section of the sorbitol molecule was measured using monoenergetic electron beam. Possible fragmentation pathways for the sorbitol molecule were proposed.

  7. Culture conditions and sample preparation methods affect spectrum quality and reproducibility during profiling of Staphylococcus aureus with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Goldstein, J E; Zhang, L; Borror, C M; Rago, J V; Sandrin, T R

    2013-08-01

    Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as a promising tool to rapidly characterize Staphylococcus aureus. Different protocols have been employed, but effects of experimental factors, such as culture condition and sample preparation, on spectrum quality and reproducibility have not been rigorously examined. We applied MALDI-TOF MS to characterize a model system consisting of five methicillin-sensitive (MSSA) and five methicillin-resistant S. aureus isolates (MRSA) under two culture conditions (agar and broth) and using two sample preparation methods [intact cell method and protein extraction method (PEM)]. The effects of these treatments on spectrum quality and reproducibility were quantified. PEM facilitated increases in the number of peaks and mass range width. Broth cultures further improved spectrum quality in terms of increasing the number of peaks. In addition, PEM increased reproducibility in samples prepared using identical culture conditions. MALDI imaging data suggested that the improvement in reproducibility may result from a more homogeneous distribution of sample associated with the broth/PEM treatment. Broth/PEM treatment also yielded the highest rate (96%) of correct classification for MRSA. Taken together, these results suggest that broth/PEM maximizes the performance of MALDI-TOF MS to characterize S. aureus. Two culture conditions (agar or broth) and two sample preparation methods (intact cell or protein extraction) were evaluated for their effects on profiling of Staphylococcus aureus using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Results indicated that MALDI-enabled profiling of S. aureus is most effective when cultures are grown in broth and processed using a protein extraction-based approach. These findings should enhance future efforts to maximize the performance of this approach to characterize strains of S. aureus. © 2013

  8. Improved gas chromatography-negative ion chemical ionization tandem mass spectrometric method for determination of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in hair using mechanical pulverization and bead-assisted liquid-liquid extraction.

    PubMed

    Kim, Jin Young; Cheong, Jae Chul; Lee, Jae Il; In, Moon Kyo

    2011-03-20

    A gas chromatography-negative ion chemical ionization tandem mass spectrometric (GC-NCI-MS/MS) method was developed and validated for the determination of 11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in human hair. After decontamination, hair samples were weighed (25mg), mechanically pulverized with a bead mill, and incubated in 0.7 mL of 1.0M sodium hydroxide at 95 °C for 30 min. Bead-assisted liquid-liquid extraction was performed with n-hexane:ethyl acetate (9:1, v/v), a method developed in our laboratory. The extract was evaporated to dryness, derivatized with pentafluoropropanol and pentafluoropropionic anhydride, and analyzed by GC-MS/MS in the negative ion chemical ionization mode using methane as the reagent gas. The linear ranges were 0.05-10.0 pg/mg for THC-COOH with the coefficient of determination (r(2) = 0.9976). The intra-day and inter-day precisions were within 1.7 and 13.8%, respectively. The intra-day and inter-day accuracies were -4.8 to 10.0% and -3.9 to 3.8%, respectively. The limit of detection and quantification were 0.015 and 0.05 pg/mg, respectively. The recoveries were in the range of 79.4-87.1%. The results indicate that the proposed method is simple, rapid, accurate, and precise for determination of THC-COOH in hair. The method identified THC-COOH in hair specimens from suspected marijuana abusers.

  9. Phase space density as a measure of cooling performance for the international muon ionization cooling experiment

    SciTech Connect

    Berg, J. S.

    2015-05-03

    The International Muon Ionization Cooling Experiment (MICE) is an experiment to demonstrate ionization cooling of a muon beam in a beamline that shares characteristics with one that might be used for a muon collider or neutrino factory. I describe a way to quantify cooling performance by examining the phase space density of muons, and determining how much that density increases. This contrasts with the more common methods that rely on the covariance matrix and compute emittances from that. I discuss why a direct measure of phase space density might be preferable to a covariance matrix method. I apply this technique to an early proposal for the MICE final step beamline. I discuss how matching impacts the measured performance.

  10. Blending online techniques with traditional face to face teaching methods to deliver final year undergraduate radiology learning content.

    PubMed

    Howlett, David; Vincent, Tim; Watson, Gillian; Owens, Emma; Webb, Richard; Gainsborough, Nicola; Fairclough, Jil; Taylor, Nick; Miles, Ken; Cohen, Jon; Vincent, Richard

    2011-06-01

    To review the initial experience of blending a variety of online educational techniques with traditional face to face or contact-based teaching methods to deliver final year undergraduate radiology content at a UK Medical School. The Brighton and Sussex Medical School opened in 2003 and offers a 5-year undergraduate programme, with the final 5 spent in several regional centres. Year 5 involves several core clinical specialities with onsite radiology teaching provided at regional centres in the form of small-group tutorials, imaging seminars and also a one-day course. An online educational module was introduced in 2007 to facilitate equitable delivery of the year 5 curriculum between the regional centres and to support students on placement. This module had a strong radiological emphasis, with a combination of imaging integrated into clinical cases to reflect everyday practice and also dedicated radiology cases. For the second cohort of year 5 students in 2008 two additional online media-rich initiatives were introduced, to complement the online module, comprising imaging tutorials and an online case discussion room. In the first year for the 2007/2008 cohort, 490 cases were written, edited and delivered via the Medical School managed learning environment as part of the online module. 253 cases contained a form of image media, of which 195 cases had a radiological component with a total of 325 radiology images. Important aspects of radiology practice (e.g. consent, patient safety, contrast toxicity, ionising radiation) were also covered. There were 274,000 student hits on cases the first year, with students completing a mean of 169 cases each. High levels of student satisfaction were recorded in relation to the online module and also additional online radiology teaching initiatives. Online educational techniques can be effectively blended with other forms of teaching to allow successful undergraduate delivery of radiology. Efficient IT links and good image quality

  11. Determination of the first ionization potential of berkelium and californium by resonance ionization mass spectroscopy

    SciTech Connect

    Nunnemann, M.; Eberhardt, K.; Erdmann, N.; Herrmann, G.; Huber, G.; Koehler, S.; Kratz, J. V.; Naehler, A.; Passler, G.; Trautmann, N.

    1997-01-15

    Resonance ionization mass spectroscopy (RIMS) is used for the precise determination of the first ionization potential (IP) of transuranium elements. Small amounts of material ({approx_equal}0.4 ng) are sufficient for these measurements due to the high sensitivity of RIMS enabling the investigation of the actinides beyond plutonium, which are accessible only in limited amounts and difficult to handle due to their high radioactivity. The method presented takes advantage of the dependence of the ionization threshold on an external static electric field. With samples of 10{sup 12} atoms of {sup 249}Bk and {sup 249}Cf experimental values for the first ionization potentials of IP{sub Bk}=49989(2) cm{sup -1} and IP{sub Cf}=50665(2) cm{sup -1} were obtained.

  12. Determination of the first ionization potential of berkelium and californium by resonance ionization mass spectroscopy

    SciTech Connect

    Nunnemann, M.; Eberhardt, K.; Erdmann, N.; Herrmann, G.; Huber, G.; Koehler, S.; Kratz, J.V.; Naehler, A.; Passler, G.; Trautmann, N.

    1997-01-01

    Resonance ionization mass spectroscopy (RIMS) is used for the precise determination of the first ionization potential ({ital IP}) of transuranium elements. Small amounts of material ({approx}0.4ng) are sufficient for these measurements due to the high sensitivity of RIMS enabling the investigation of the actinides beyond plutonium, which are accessible only in limited amounts and difficult to handle due to their high radioactivity. The method presented takes advantage of the dependence of the ionization threshold on an external static electric field. With samples of 10{sup 12} atoms of {sup 249}Bk and {sup 249}Cf experimental values for the first ionization potentials of IP{sub Bk}=49989(2)cm{sup {minus}1} and IP{sub Cf}=50665(2)cm{sup {minus}1} were obtained. {copyright} {ital 1997 American Institute of Physics.}

  13. Gridded electron reversal ionizer

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor)

    1993-01-01

    A gridded electron reversal ionizer forms a three dimensional cloud of zero or near-zero energy electrons in a cavity within a filament structure surrounding a central electrode having holes through which the sample gas, at reduced pressure, enters an elongated reversal volume. The resultant negative ion stream is applied to a mass analyzer. The reduced electron and ion space-charge limitations of this configuration enhances detection sensitivity for material to be detected by electron attachment, such as narcotic and explosive vapors. Positive ions may be generated by generating electrons having a higher energy, sufficient to ionize the target gas and pulsing the grid negative to stop the electron flow and pulsing the extraction aperture positive to draw out the positive ions.

  14. Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Kelly, Ryan T.; Marginean, Ioan; Tang, Keqi

    2014-06-13

    Electrospray Ionization (ESI) is a process whereby gas phase ions are created from molecules in solution. As a solution exits a narrow tube in the presence of a strong electric field, an aerosol of charged droplets are is formed that produces gas phase ions as they it desolvates. ESI-MS comprises the creation of ions by ESI and the determination of their mass to charge ratio (m/z) by MS.

  15. Hysteresis of ionization waves

    SciTech Connect

    Dinklage, A.; Bruhn, B.; Testrich, H.; Wilke, C.

    2008-06-15

    A quasi-logistic, nonlinear model for ionization wave modes is introduced. Modes are due to finite size of the discharge and current feedback. The model consists of competing coupled modes and it incorporates spatial wave amplitude saturation. The hysteresis of wave mode transitions under current variation is reproduced. Sidebands are predicted by the model and found in experimental data. The ad hoc model is equivalent to a general--so-called universal--approach from bifurcation theory.

  16. EPA (Environmental Protection Agency) method study 24, method 601--purgeable halocarbons by the purge trap method. Final report September 1979-December 1982

    SciTech Connect

    Warner, B.J.; Friedman, C.S.; Metcalfe, L.; Morrow, T.J.; Snyder, A.D.

    1984-07-01

    The experimental design and results of a validations study for an analytical method to detect 29 halocarbons in water are described herein. In Method 601, the halocarbons are purged by an inert gas which is bubbled through the aqueous sample. The vapors are then trapped in a short column containing a suitable sorbent. The trapped components are then thermally desorbed onto the head of a chromatographic column and measured by means of halide specific detector. In this study, the 29 halocarbon compounds were divided into three separate mixes to minimize interferences from co-eluting peaks. The spiking solutions employed in the study contained the 29 halocarbons at six concentrations. Six water matrices were used in the study: distilled water, drinking water, and a surface water all supplied by the cooperating laboratories; and three industrial wastewaters supplied by the Monsanto Company. Statistical analyses and conclusions in this report are based on analytical data obtained by 20 collaborating laboratories.

  17. Design and validation of a high-throughput matrix-assisted laser desorption ionization time-of-flight mass spectrometry method for quantification of hepcidin in human plasma.

    PubMed

    Anderson, Damon S; Kirchner, Marc; Kellogg, Mark; Kalish, Leslie A; Jeong, Jee-Yeong; Vanasse, Gary; Berliner, Nancy; Fleming, Mark D; Steen, Hanno

    2011-11-01

    Disorders of iron metabolism affect over a billion people worldwide. The circulating peptide hormone hepcidin, the central regulator of iron distribution in mammals, holds great diagnostic potential for an array of iron-associated disorders, including iron loading (β-thalassemia), iron overload (hereditary hemochromatosis), and iron deficiency diseases. We describe a novel high-throughput matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry assay for quantification of hepcidin in human plasma. This assay involves enrichment using a functionalized MALDI chip, a novel solvent-detergent precipitation buffer, and quantification using a stable isotope labeled internal standard. The linear range of hepcidin in plasma was 1-120 nM, with a low limit of quantification (LOQ) (1 nM), high accuracy (<15% relative error (RE)), and high precision (intraday average 5.52-18.48% coefficient of variation (CV) and interday 9.32-14.83% CV). The assay showed strong correlation with an established hepcidin immunoassay (Spearman; R(2) = 0.839 n = 93 ethylenediaminetetraacetic acid (EDTA) plasma). A collection of normal healthy pediatric samples (range 3.8-32.5 ng/mL; mean 12.9 ng/mL; n = 119) showed significant differences from an adult collection (range 1.8-48.7 ng/mL; mean 16.1 ng/mL; n = 95; P = 0.0096). We discuss these preliminary reference ranges and correlations with additional parameters in light of the utility and limitations of hepcidin measurements as a stand-alone diagnostic and as a tool for therapeutic intervention.

  18. Rigorous Incorporation of Tautomers, Ionization Species, and Different Binding Modes into Ligand-Based and Receptor-Based 3D-QSAR Methods

    PubMed Central

    Natesan, Senthil; Balaz, Stefan

    2013-01-01

    Speciation of drug candidates and receptors caused by ionization, tautomerism, and/or covalent hydration complicates ligand- and receptor-based predictions of binding affinities by 3-dimensional structure-activity relationships (3D-QSAR). The speciation problem is exacerbated by tendency of tautomers to bind in multiple conformations or orientations (modes) in the same binding site. New forms of the 3D-QSAR correlation equations, capable of capturing this complexity, can be developed using the time hierarchy of all steps that lie behind the monitored biological process – binding, enzyme inhibition or receptor activity. In most cases, reversible interconversions of individual ligand and receptor species can be treated as quickly established equilibria because they are finished in a small fraction of the exposure time that is used to determine biological effects. The speciation equilibria are satisfactorily approximated by invariant fractions of individual ligand and receptor species for buffered experimental or in vivo conditions. For such situations, the observed drug-receptor association constant of a ligand is expressed as the sum of products, for each ligand and receptor species pair, of the association microconstant and the fractions of involved species. For multiple binding modes, each microconstant is expressed as the sum of microconstants of individual modes. This master equation leads to new 3D-QSAR correlation equations integrating the results of all molecular simulations or calculations, which are run for each ligand-receptor species pair separately. The multispecies, multimode 3D-QSAR approach is illustrated by a ligand-based correlation of transthyretin binding of thyroxine analogs and by a receptor-based correlation of inhibition of MK2 by benzothiophenes and pyrrolopyrimidines. PMID:23170882

  19. Dynamical core polarization in strong-field ionization

    NASA Astrophysics Data System (ADS)

    Zhao, Zengxiu; Zhang, Bin; Yuan, Jianmin

    2014-05-01

    Core polarization plays an important role in both ionization and high harmonic generation processes of molecules driven by strong laser fields. With our recently developed three-dimensional time-dependent Hartree-Fock method, we investigate the orientation-dependent ionization of CO molecules. It is found that the full ionization results are in good agreement with the recent experiment. The comparisons between the full method and the single-active-orbital method show that although the core electrons are generally more tightly bound and contribute little to the total ionization yields, their dynamics cannot be ignored, which effectively modifies the behavior of electrons in the HOMO. By incorporating it into the SAO method, we identify that the dynamic core polarization plays an important role in the tunneling ionization of CO molecules, which is helpful for the future development of the tunneling ionization theory beyond the single active electron approximation. In order to further verify the role of core polarization, exact calculations are performed for the ionization of two-electron model systems by strong laser fields. The limitations of HF and the SAE are quantified and the tunneling ionization rate is shown improved with the core-polarization induced correction.

  20. Multifunctional Carbon Fiber Ionization Mass Spectrometry.

    PubMed

    Wu, Meng-Xi; Wang, Hao-Yang; Zhang, Jun-Ting; Guo, Yin-Long

    2016-10-04

    A carbon fiber ionization (CFI) technique was developed for the mass spectrometric analysis of various organic compounds with different polarities. The design of the CFI technique was based on the good compatibility and dispersion of samples and solutions in different solvents on carbon fiber. As a fast, convenient, and versatile ionization method, CFI-MS is especially efficient for analyzing many low/nonpolar organic compounds, such as polycyclic aromatic hydrocarbons, long-chain aliphatic aldehydes, sensitive steroids, terpenoids, and organometallic compounds. Some of these compounds may not be well-analyzed by electrospray ionization or electron ionization mass spectrometry. On the basis of our experimental results, the major ion formation mechanism of CFI-MS was suggested to involve desorption in a steam-distillation-like process, and then, ionization occurred mainly via corona discharge under high voltage. CFI-MS could not only work alone but also be coupled with separation techniques. It works well when coupled with supercritical fluid chromatography (SFC) as well as in the analysis of exhaled human air. The high flexibility and versatility of CFI-MS has extended its applications in many areas, such as fast chemical screening, clinical testing, and forensic analysis.

  1. Non-dissociative and dissociative ionization of a CO+ beam in intense ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Gaire, B.; Ablikim, U.; Zohrabi, M.; Roland, S.; Carnes, K. D.; Ben-Itzhak, I.

    2011-05-01

    We have investigated the ionization of CO+ beams in intense ultrashort laser pulses. With the recent upgrades to our coincidence three-dimensional momentum imaging method we are able to measure both non-dissociative and dissociative ionization of the molecular-ion beam targets. Using CO+ as an example, we have found that non-dissociative ionization (leading to the metastable dication CO2+) involves a direct transition, i.e. the molecule is ionized with little or no internuclear distance stretch. Dissociative ionization (C+ + O+) occurs both directly and indirectly, stretching first and then ionizing. Our results show that the yield of dissociative ionization is higher than that of non-dissociative ionization and can be manipulated with the laser pulse duration by suppressing the indirect ionization path using ultrashort pulses (<=10 fs). Supported by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

  2. Development and validation of a sensitive gas chromatography-ammonia chemical ionization mass spectrometry method for the determination of tabun enantiomers in hemolysed blood and plasma of different species.

    PubMed

    Tenberken, Oliver; Worek, Franz; Thiermann, Horst; Reiter, Georg

    2010-05-15

    The aim of this study was to develop and validate a fast, sensitive and easily applicable GC-MS assay for the chiral quantification of the highly toxic organophosphorus compound tabun (O-ethyl-N,N-dimethylphosphoramidocyanidate, GA) in hemolysed swine blood for further use in toxicokinetic and toxicodynamic studies. These requirements were fulfilled best by a GC-MS assay with positive chemical ionization with ammonia (GC-PCI-MS). Separation was carried out on a beta-cyclodextrin capillary column (Supelco BetaDex 225) after reversed phase (C18) solid-phase extraction. The limit of detection was 1 pg/ml for each enantiomer (approximately 500 fg on column) and the limit of quantification 5 pg/ml. The GC-PCI-MS method was applied for the quantification of tabun enantiomers in spiked swine blood after hemolysis and in spiked plasma of different species including humans.

  3. The method for on-site determination of trace concentrations of methyl mercaptan and dimethyl sulfide in air using a mobile mass spectrometer with atmospheric pressure chemical ionization, combined with a fast enrichment/separation system.

    PubMed

    Kudryavtsev, Andrey S; Makas, Alexey L; Troshkov, Mikhail L; Grachev, Mikhail А; Pod'yachev, Sergey P

    2014-06-01

    A method for fast simultaneous on-site determination of methyl mercaptan and dimethyl sulfide in air was developed. The target compounds were actively collected on silica gel, followed by direct flash thermal desorption, fast separation on a short chromatographic column and detection by means of mass spectrometer with atmospheric pressure chemical ionization. During the sampling of ambient air, water vapor was removed with a Nafion selective membrane. A compact mass spectrometer prototype, which was designed earlier at Trofimuk Institute of Petroleum Geology and Geophysics, was used. The minimization of gas load of the atmospheric pressure ion source allowed reducing the power requirements and size of the vacuum system and increasing its ruggedness. The measurement cycle is about 3 min. Detection limits in a 0.6 L sample are 1 ppb for methyl mercaptan and 0.2 ppb for dimethyl sulfide. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. The Final Count Down: A Review of Three Decades of Flight Controller Training Methods for Space Shuttle Mission Operations

    NASA Technical Reports Server (NTRS)

    Dittemore, Gary D.; Bertels, Christie

    2011-01-01

    Operations of human spaceflight systems is extremely complex, therefore the training and certification of operations personnel is a critical piece of ensuring mission success. Mission Control Center (MCC-H), at the Lyndon B. Johnson Space Center, in Houston, Texas manages mission operations for the Space Shuttle Program, including the training and certification of the astronauts and flight control teams. As the space shuttle program ends in 2011, a review of how training for STS-1 was conducted compared to STS-134 will show multiple changes in training of shuttle flight controller over a thirty year period. This paper will additionally give an overview of a flight control team s makeup and responsibilities during a flight, and details on how those teams have been trained certified over the life span of the space shuttle. The training methods for developing flight controllers have evolved significantly over the last thirty years, while the core goals and competencies have remained the same. In addition, the facilities and tools used in the control center have evolved. These changes have been driven by many factors including lessons learned, technology, shuttle accidents, shifts in risk posture, and generational differences. A primary method used for training Space Shuttle flight control teams is by running mission simulations of the orbit, ascent, and entry phases, to truly "train like you fly." The reader will learn what it is like to perform a simulation as a shuttle flight controller. Finally, the paper will reflect on the lessons learned in training for the shuttle program, and how those could be applied to future human spaceflight endeavors.

  5. Nucleation in an Ultra Low Ionization Environment

    NASA Astrophysics Data System (ADS)

    Pedersen, J. O.; Enghoff, M. B.; Paling, S.; Svensmark, H.

    2010-12-01

    Atmospheric ions can enhance the nucleation of aerosols, as has been established by experiments, observation, and theory. In the clean marine atmosphere ionization is mainly caused by cosmic rays which in turn are controlled by the activity of the Sun, thus providing a potential link between solar activity and climate. In order to understand the effect ions may have on the production of cloud condensation nuclei the overall contribution of ion induced nucleation to the global production of secondary aerosols must be determined. One issue with determining this contribution is that several mechanisms for nucleation exist and it can be difficult to determine the relative importance of the various mechanisms in a given nucleation event when both ion induced and electrically neutral nucleation mechanisms are at work at the same time. We have carried out nucleation experiments in the Boulby Underground Laboratory, located 1100 meters below ground, thus reducing the flux of ionizing cosmic radiation by six orders of magnitude. Similarly we have reduced the gamma background by shielding the experiment in lead and copper. Finally we have used air stored for several weeks and passed through an active charcoal filter in order to reduce the Radon concentration. In this way we have been able to make nucleation experiments with very low ionizing background, meaning that we can rule out ion induced nucleation as a contributing mechanism. Our experimental setup is a 50 L electropolished stainless steel reactor at near atmospheric conditions. The chamber contains clean air with the addition of water vapor, ozone, and SO2. Using UV lights at 254 nm ozone is photolyzed, leading to the production of sulfuric acid and thus aerosols. An 18 MBq Caesium-137 gamma ray source with various amounts of lead in front allows us to alter the ionization in our chamber. By making series of nucleation bursts with varying amounts of ionizing radiation we then gauge the relative importance of ion

  6. Comparison of ultra-high performance methods in liquid and supercritical fluid chromatography coupled to electrospray ionization - mass spectrometry for impurity profiling of drug candidates.

    PubMed

    Lemasson, Elise; Bertin, Sophie; Hennig, Philippe; Lesellier, Eric; West, Caroline

    2016-11-11

    Impurity profiling of organic products synthesized as possible drug candidates represents a major analytical challenge. Complementary analytical methods are required to ensure that all impurities are detected. Both high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) can be used for this purpose. In this study, we compared ultra-high performance HPLC (UHPLC) and ultra-high performance SFC (UHPSFC) using a large dataset of 140 pharmaceutical compounds. Four previously optimized methods (two on each technique) were selected to ensure fast high-resolution separations. The four methods were evaluated based on response rate, peak capacity, peak shape and capability to detect impurities (UV). The orthogonality between all methods was also assessed. The best UHPLC method and UHPSFC methods provided comparable quality for the 140 compounds included in this study. Moreover, they were found to be highly orthogonal. At last, the potential of the combined use of UHPLC and UHPSFC for impurity profiling is illustrated with practical examples.

  7. Orbital-resolved nonadiabatic tunneling ionization

    NASA Astrophysics Data System (ADS)

    Zhang, Qingbin; Basnayake, Gihan; Winney, Alexander; Lin, Yun Fei; Debrah, Duke; Lee, Suk Kyoung; Li, Wen

    2017-08-01

    In this theoretical work, we show that both the orbital helicity (p+ vs p-) and the adiabaticity of tunneling have a significant effect on the initial conditions of tunneling ionization. We developed a hybrid quantum (numerical solution of the time-dependent Schrödinger equation) and classical (back propagation of trajectories) approach to extract orbital-specific initial conditions of electrons at the tunneling exit. Clear physical insight connecting these initial conditions with the final momentum and deflection angles of electrons are presented. Moreover, the adiabaticity of tunneling ionization is characterized by comparing the initial conditions with those with a static field. Significant nonadiabatic tunneling is found to persist beyond a Keldysh parameter of less than 0.5.

  8. A quantitative headspace-solid-phase microextraction-gas chromatography-flame ionization detector method to analyze short chain free fatty acids in rat feces.

    PubMed

    Fiorini, Dennis; Boarelli, Maria Chiara; Gabbianelli, Rosita; Ballini, Roberto; Pacetti, Deborah

    2016-09-01

    This study sought to develop and validate a quantitative method to analyze short chain free fatty acids (SCFAs) in rat feces by solid-phase microextraction and gas chromatography (SPME-GC) using the salt mixture ammonium sulfate and sodium dihydrogen phosphate as salting out agent. Conditioning and extraction time, linearity, limits of detection and quantification, repeatability, and recovery were evaluated. The proposed method allows quantification with improved sensitivity as compared with other methods exploiting SPME-GC. The method has been applied to analyze rat fecal samples, quantifying acetic, propionic, isobutyric, butyric, isopentanoic, pentanoic, and hexanoic acids. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Investigation of Ionization and Dissociation Processes Produced by Electron Impact on Molecules.

    NASA Astrophysics Data System (ADS)

    Ma, Ce.

    1990-01-01

    Absolute electron impact partial ionization cross sections for Ar and CF_4 were measured by use of a newly built pulsed electron beam time-of-flight apparatus for incident electron energies from thresholds to 500 eV. The apparatus employed consisted of a low energy electron gun, 40 mm diameter ion extraction gold screens, time-of-flight drift tubes, micro-channel plate detectors and fast time to digital electronics. A pulsed electron beam was obtained by pulsing the control grid of the electron gun. Both beam - beam experiments and beam - constant gas target pressure experiments were carried out to determine the absolute partial ionization cross sections for Ar ^{+}, Ar^{2+ }, Ar^{3+} from an argon gas target, and for CF_sp {3}{+}, CF_sp {2}{+}, CF_sp {3}{2+}, CF^ {+}, CF_sp{2} {2+}, F^{+}, C^{+} from a CF _4 gas target. By charge weighted summing of the partial ionization cross sections, the total ionization cross sections of Ar and CF_4 were obtained. The total neutral dissociation cross section for CF_4 was inferred from the total ionization cross section and the total dissociation cross section. Also, a new method for determining absolute total electron scattering cross sections with corrections for forward scattering was developed. The electron beam current was measured as function of gas target pressure and the scattering path length. The total electron scattering cross section obtained from the new model is as much as 6% larger than the cross section derived from the traditional Beer's law for Ar at an incident electron energy of 300 eV. This method is capable of yielding reliable total cross section up to 10 keV. Finally, a study of the secondary electron emission as a function of ejection angle and ejection energy for CO, the doubly differential cross section (DDCS), is presented.

  10. Calcium: total or ionized?

    PubMed

    Schenck, Patricia A; Chew, Dennis J

    2008-05-01

    Measurement of serum total calcium (tCa) has been relied on for assessment of calcium status, despite the fact that it is the ionized calcium (iCa) fraction that has biologic activity. Serum tCa does not accurately predict iCa status in many clinical conditions. For accurate assessment of iCa status, iCa should be directly measured. Anaerobic measurement of serum iCa under controlled conditions provides the most reliable assessment of calcium status; aerobic measurement of iCa with species-specific pH correction is highly correlated with anaerobic measurements.

  11. Above-threshold ionization through Rydberg state population

    NASA Astrophysics Data System (ADS)

    Xin, Pei Pei; Yuan, Ming Hu; Wang, Han Mu; Yang, Hai Feng; Liu, Hong Ping

    2017-04-01

    We present a theoretical scenario for the atomic above-threshold ionization (ATI) in an intense laser field by investigating the Rydberg state population in real time. Rather than merely viewing the final distribution of photoelectron yield directly, we monitor the Rydberg state population by projecting the time-dependent wave function onto the bound eigen-states. The calculation shows that the population of resonant Rydberg states is closely related to the peaks in photoelectron kinetic energy spectrum (PKES). For a hydrogen atom, the highest populated Rydberg states are degenerated, exactly corresponding to the first ATI peak if one additional photon is absorbed. While for non-hydrogen atoms, e.g., Ar, the highest Rydberg states are mainly populated on specific states, e.g., 3 d (5 s) and 4f in our case, also giving exact peak positions in PKES, where the state identification is obtained by the angular momentum resolved distribution of excited Rydberg states. This method provides an easy to understand picture for the resonance-enhanced effects in ATI as well as the role of atomic core potential in strong-field ionization.

  12. Observation and identification of metastable excited states in ultrafast laser-ionized pyridine.

    PubMed

    Foote, David B; Scarborough, Timothy D; Uiterwaal, Cornelis J G J

    2012-05-01

    We report on the fragmentation of ionized pyridine (C(5)H(5)N) molecules by focused 50 fs, 800 nm laser pulses. Such ionization produces several metastable ionic states that fragment within the field-free drift region of a reflectron-type time of flight mass spectrometer, with one particular metastable dissociation being the leading fragmentation process. Because the time of flight is no longer dependent in a simple way on the mass of the ion, the metastable decay is manifested as an unfocused peak on the mass spectrum that appears at a time of flight not corresponding to an integer mass. A previously-developed method is used to identify the precursor and final masses of these ions. The metastable process that creates the most prevalent peak is shown to be C(5)H(5)N(+) → C(4)H(4)(+) + HCN. Simulations confirm this result and place restrictions on the processes for several other observed metastable reactions.

  13. Assessment of nonequilibrium radiation computation methods for hypersonic flows

    NASA Technical Reports Server (NTRS)

    Sharma, Surendra

    1993-01-01

    The present understanding of shock-layer radiation in the low density regime, as appropriate to hypersonic vehicles, is surveyed. Based on the relative importance of electron excitation and radiation transport, the hypersonic flows are divided into three groups: weakly ionized, moderately ionized, and highly ionized flows. In the light of this division, the existing laboratory and flight data are scrutinized. Finally, an assessment of the nonequilibrium radiation computation methods for the three regimes in hypersonic flows is presented. The assessment is conducted by comparing experimental data against the values predicted by the physical model.

  14. Plasma Production via Field Ionization

    SciTech Connect

    O'Connell, C.L.; Barnes, C.D.; Decker, F.; Hogan, M.J.; Iverson, R.; Krejcik, P.; Siemann, R.; Walz, D.R.; Clayton, C.E.; Huang, C.; Johnson, D.K.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Zhou, M.; Deng, S.; Katsouleas, T.; Muggli, P.; Oz, E.; /Southern California U.

    2007-01-02

    Plasma production via field ionization occurs when an incoming particle beam is sufficiently dense that the electric field associated with the beam ionizes a neutral vapor or gas. Experiments conducted at the Stanford Linear Accelerator Center explore the threshold conditions necessary to induce field ionization by an electron beam in a neutral lithium vapor. By independently varying the transverse beam size, number of electrons per bunch or bunch length, the radial component of the electric field is controlled to be above or below the threshold for field ionization. Additional experiments ionized neutral xenon and neutral nitric oxide by varying the incoming beam's bunch length. A self-ionized plasma is an essential step for the viability of plasma-based accelerators for future high-energy experiments.

  15. Quantitative method for analysis of monensin in soil, water, and urine by direct combination of single-drop microextraction with atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Sekar, Ramaiyan; Wu, Hui-Fen

    2006-09-15

    A simple and selective analytical method for the quantitative determination of low concentrations of monensin in soil, surface water, and human urine has been developed. Prior to atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI-MS) analysis, the samples were preconcentrated by using the single-drop microextraction (SDME) technique. Several factors that affect the analyte's extraction, including selection of solvent, microdrop volume, extraction time, and ionic strength, were investigated. Chloroform-toluene (1:1, v/v) was selected as the extraction solvent. Reliable results were obtained using dibenzo-30-crown-10-ether as an internal standard. The proposed method has been successfully applied for the determination of monensin in soil, surface water, and human urine spiked samples. Under the optimized conditions, the limits of quantification of the analyte in surface water, soil, and human urine were 6.7, 12.4 and 7.8 ng/mL, respectively. The intraday and interday precision variation and accuracy of the present method is within the acceptable ranges. The present method avoids the pre- and postderivatization of weak UV absorbing monensin determination using high performance liquid chromatography-ultraviolet detection (HPLC-UV). Furthermore, these techniques are time-consuming, nonreproducible at trace levels, and form undesirable products. The proposed SDME combined with AP-MALDI-MS is simple, fast, and selective for the determination of monensin in environmental and urine samples.

  16. Robust method for investigating nitrogen metabolism of 15N labeled amino acids using AccQ•Tag ultra performance liquid chromatography-photodiode array-electrospray ionization-mass spectrometry: application to a parasitic plant-plant interaction.

    PubMed

    Gaudin, Zachary; Cerveau, Delphine; Marnet, Nathalie; Bouchereau, Alain; Delavault, Philippe; Simier, Philippe; Pouvreau, Jean-Bernard

    2014-01-21

    An AccQ•Tag ultra performance liquid chromatography-photodiode array-electrospray ionization-mass spectrometry (AccQ•Tag-UPLC-PDA-ESI-MS) method is presented here for the fast, robust, and sensitive quantification of (15)N isotopologue enrichment of amino acids in biological samples, as for example in the special biotic interaction between the cultivated specie Brassica napus (rapeseed) and the parasitic weed Phelipanche ramosa (broomrape). This method was developed and validated using amino acid standard solutions containing (15)N amino acid isotopologues and/or biological unlabeled extracts. Apparatus optimization, limits of detection and quantification, quantification reproducibility, and calculation method of (15)N isotopologue enrichment are presented. Using this method, we could demonstrate that young parasite tubercles assimilate inorganic nitrogen as (15)N-ammonium when supplied directly through batch incubation but not when supplied by translocation from host root phloem, contrary to (15)N2-glutamine. (15)N2-glutamine mobility from host roots to parasite tubercles followed by its low metabolism in tubercles suggests that the host-derived glutamine acts as an important nitrogen containing storage compound in the young tubercle of Phelipanche ramosa.

  17. Comparison of in-gel and on-membrane digestion methods at low to sub-pmol level for subsequent peptide and fragment-ion mass analysis using matrix-assisted laser-desorption/ionization mass spectrometry.

    PubMed

    Courchesne, P L; Luethy, R; Patterson, S D

    1997-01-01

    The success of the mass spectrometric-based approaches for the identification of gel-separated proteins relies upon recovery of peptides, without high levels of ionization-suppressing contaminants, in solvents compatible with the mass spectrometer being employed. We sought to determine whether in-gel or on-membrane digestion provided a significant advantage when low to sub-pmol quantities of gel-separated proteins were analyzed by matrix-assisted laser-desorption/ionization mass spectrometry (MALDI-MS) with respect to the number and size of released peptides. Serial dilutions of five standard proteins of M(r) 17,000 to 97,000 (from 16 pmol to 125 fmol) were electrophoresed and subjected to in-gel digestion (using a microcolumn clean-up protocol, Courchesne, P.L. and Patterson, S. D., BioTechniques, 1997, in press) or on-membrane digestion following blotting to the PVDF-based membranes, Immobilon-P and Immobilon-CD. Peptide maps were able to be obtained for all proteins at the detection limit of each method (Immobilon-P and Immobilon-CD, 0.5 pmol; and in-gel, 125 fmol), and searches of Swiss-Prot or a non-redundant database (> 193000 entries) successfully identified all of the proteins, except beta-casein. Fragment-ion spectra using a curved-field reflector MALDI-MS were obtained from more than one peptide per protein at loads down to 250 fmol (except beta-casein). Using the uninterpreted data, a search of the nonredundant database and a six-way translation of GenBank dbEST (> 2,208,000 entries total) was able to identify myoglobin, carbonic anhydrase II, and phosphorylase b.

  18. Simultaneous quantification of acetaminophen and five acetaminophen metabolites in human plasma and urine by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry: Method validation and application to a neonatal pharmacokinetic study.

    PubMed

    Cook, Sarah F; King, Amber D; van den Anker, John N; Wilkins, Diana G

    2015-12-15

    Drug metabolism plays a key role in acetaminophen (paracetamol)-induced hepatotoxicity, and quantification of acetaminophen metabolites provides critical information about factors influencing susceptibility to acetaminophen-induced hepatotoxicity in clinical and experimental settings. The aims of this study were to develop, validate, and apply high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) methods for simultaneous quantification of acetaminophen, acetaminophen-glucuronide, acetaminophen-sulfate, acetaminophen-glutathione, acetaminophen-cysteine, and acetaminophen-N-acetylcysteine in small volumes of human plasma and urine. In the reported procedures, acetaminophen-d4 and acetaminophen-d3-sulfate were utilized as internal standards (IS). Analytes and IS were recovered from human plasma (10μL) by protein precipitation with acetonitrile. Human urine (10μL) was prepared by fortification with IS followed only by sample dilution. Calibration concentration ranges were tailored to literature values for each analyte in each biological matrix. Prepared samples from plasma and urine were analyzed under the same HPLC-ESI-MS/MS conditions, and chromatographic separation was achieved through use of an Agilent Poroshell 120 EC-C18 column with a 20-min run time per injected sample. The analytes could be accurately and precisely quantified over 2.0-3.5 orders of magnitude. Across both matrices, mean intra- and inter-assay accuracies ranged from 85% to 112%, and intra- and inter-assay imprecision did not exceed 15%. Validation experiments included tests for specificity, recovery and ionization efficiency, inter-individual variability in matrix effects, stock solution stability, and sample stability under a variety of storage and handling conditions (room temperature, freezer, freeze-thaw, and post-preparative). The utility and suitability of the reported procedures were illustrated by analysis of pharmacokinetic samples

  19. Theory of multiphoton single and double ionization of two-electron atomic systems driven by short-wavelength electric fields: An ab initio treatment

    SciTech Connect

    Foumouo, Emmanuel; Piraux, Bernard; Kamta, Gerard Lagmago; Edah, Gaston

    2006-12-15

    We give a detailed account of an ab initio computational treatment of multiphoton single ionization (with or without excitation) as well as double ionization of two-electron atoms exposed to short-wavelength electric fields. This treatment is time dependent and based on a spectral method of configuration interaction type combined with Jacobi or J-matrix calculations. It involves a complete treatment of electron-electron correlation in the initial and final states as well as during the time propagation. The atom eigenvalue problem is first solved by means of the spectral method. It consists of expanding the atom wave function in a basis of products of complex Coulomb-Sturmian functions of the electron radial coordinates and bipolar harmonics of the angular coordinates. This method allows a high-resolution study of many atomic states, in particular high-lying singly excited states as well as many doubly excited states. Results for He are presented and discussed in detail. The time-dependent Schroedinger equation is then solved by means of an explicit scheme of Runge-Kutta type. An accurate calculation of the probability of single and double ionization is carried out by projecting the ionizing wave packet on fully correlated multichannel scattering wave functions generated by means of the J-matrix method. After a detailed analysis of the accuracy of this method, we show that our results for the total cross section of one-photon single and double ionization of He and H{sup -} are in very good agreement with those obtained by the most sophisticated approaches. Two-photon double ionization of He is then considered, and results are presented in a frequency regime where substantial discrepancies subsist between all existing calculations. Our results demonstrate that electron correlations in the final state play a significant role.

  20. SW-846 Test Method 8276: Toxaphene and Toxaphene Congeners By Gas Chromatography/Negative Ion Chemical Ionization Mass Spectrometry (GC-NICI/MS)

    EPA Pesticide Factsheets

    determine the concentrations of various toxaphene congeners and technical toxaphene (with other toxaphene congeners and compounds from Method 8081) in extracts from solidliquid matrices, using fused-silica, open-tubular capillary columns with (NICI/MS).

  1. Method for discriminative particle selection

    DOEpatents

    Post, Richard F.

    1992-01-01

    The invention is a method and means for separating ions or providing an ion beam. The invention generates ions of the isotopes to be separated, and then provides a traveling electric potential hill created by a sequential series of quasi static electric potential hills. By regulating the velocity and potential amplitude of the traveling electric potential hill ionized isotopes are selectively positively or negatively accelerated. Since the ionized isotopes have differing final velocities, the isotopes may be collected separately or used to produce an ion beam of a selected isotope.

  2. Alloy nanoparticle synthesis using ionizing radiation

    DOEpatents

    Nenoff, Tina M [Sandia Park, NM; Powers, Dana A [Albuquerque, NM; Zhang, Zhenyuan [Durham, NC

    2011-08-16

    A method of forming stable nanoparticles comprising substantially uniform alloys of metals. A high dose of ionizing radiation is used to generate high concentrations of solvated electrons and optionally radical reducing species that rapidly reduce a mixture of metal ion source species to form alloy nanoparticles. The method can make uniform alloy nanoparticles from normally immiscible metals by overcoming the thermodynamic limitations that would preferentially produce core-shell nanoparticles.

  3. Quantification of endogenous metabolites by the postcolumn infused-internal standard method combined with matrix normalization factor in liquid chromatography-electrospray ionization tandem mass spectrometry.

    PubMed

    Liao, Hsiao-Wei; Chen, Guan-Yuan; Wu, Ming-Shiang; Liao, Wei-Chih; Tsai, I-Lin; Kuo, Ching-Hua

    2015-01-02

    Quantification of endogenous metabolites has enabled the discovery of biomarkers for diagnosis and provided for an understanding of disease etiology. The standard addition and stable isotope labeled-internal standard (SIL-IS) methods are currently the most widely used approaches to quantifying endogenous metabolites, but both have some limitations for clinical measurement. In this study, we developed a new approach for endogenous metabolite quantification by the postcolumn infused-internal standard (PCI-IS) method combined with the matrix normalization factor (MNF) method. MNF was used to correct the difference in MEs between standard solution and biofluids, and PCI-IS additionally tailored the correction of the MEs for individual samples. Androstenedione and testosterone were selected as test articles to verify this new approach to quantifying metabolites in plasma. The repeatability (n=4 runs) and intermediate precision (n=3 days) in terms of the peak area of androstenedione and testosterone at all tested concentrations were all less than 11% relative standard deviation (RSD). The accuracy test revealed that the recoveries were between 95.72% and 113.46%. The concentrations of androstenedione and testosterone in fifty plasma samples obtained from healthy volunteers were quantified by the PCI-IS combined with the MNF method, and the quantification results were compared with the results of the SIL-IS method. The Pearson correlation test showed that the correlation coefficient was 0.98 for both androstenedione and testosterone. We demonstrated that the PCI-IS combined with the MNF method is an effective and accurate method for quantifying endogenous metabolites.

  4. Numerical Modeling of Ion Dynamics in a Carbon Nanotube Field-Ionized Thruster

    DTIC Science & Technology

    2011-12-01

    ION SOURCES Ions may be produced by several methods: photo-ionization, electron bombardment, field ionization, surface ionization, and thermionic ...OF ION DYNAMICS IN A CARBON NANOTUBE FIELD -IONIZED ION THRUSTER by Sarah F. Michael December 2011 Thesis Advisors: Dragoslav Grbovic...December 2011 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Numerical Modeling of Ion Dynamics in a Carbon Nanotube Field

  5. New ionization processes and applications for use in mass spectrometry.

    PubMed

    Trimpin, Sarah; Wang, Beixi; Lietz, Christopher B; Marshall, Darrell D; Richards, Alicia L; Inutan, Ellen D

    2013-01-01

    Mass spectrometry (MS) continues to improve at a rapid pace as most prominently witnessed for mass analyzers and fragmentation technology. Ionization methods have also seen resurgence with ambient ionization approaches gaining a foothold because they often provide a convenient and direct means of sample analysis. Nevertheless, a vast majority of biological analyses using MS apply electrospray ionization or matrix-assisted laser desorption/ionization, methods introduced in the 1980s, or variants thereof. To further advance applications by MS such as protein characterization, and, for example, addressing their location within specific cell types, the progress in mass analyzer and fragmentation technology needs to be matched with similar advances in ionization technology. It is imperative to seek ionization methods that more efficiently convert molecules, to gas-phase ions in a way that allows high transfer efficiency to the mass analyzer and subsequently the detector to achieve a more complete picture of sample composition. This review provides a snapshot of fundamental aspects of new ionization methods and potential biological and medical applications.

  6. Analysis of beta-lactam antibiotics in incurred raw milk by rapid test methods and liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

    PubMed

    Riediker, S; Diserens, J M; Stadler, R H

    2001-09-01

    A recently developed confirmatory LC-MS method has been applied to the quantification of five major beta-lactam antibiotics in suspect raw bovine milk samples that gave a positive response with receptor-based (BetaStar) and rapid microbial inhibitory screen tests (Delvotest SP). In total, 18 presumptive positive raw milk samples were reanalyzed; 16 samples showed traces of antibiotic residues that could be identified and quantified by the LC-MS method, ranging from the limits of confirmation up to 38 microg/kg. Of the positive samples, only five (approximately 30%) were found to be violative of EU maximum residue limits. The most frequently detected antibiotic residues were cloxacillin and penicillin G, the former often in combination with amoxicillin or ampicillin. This study compares the results obtained by the three methods on identical samples and addresses how these relate to certain criteria such as sensitivity and selectivity. Furthermore, the limitations of the LC-MS method and the potential impact of the presence of frequently more than one residue in the same milk sample on the response of the rapid test methods are discussed.

  7. Ionization and Triggered Star Formation

    NASA Astrophysics Data System (ADS)

    Gritschneder, M.; Lin, D. N. C.; Murray, S. D.; Burkert, A.

    2011-12-01

    We perform a set of high resolution simulations on the impact of the UV-radiation of massive stars on the turbulent interstellar medium with the tree-SPH code iVINE. This parameter study includes different levels and driving scales of the turbulence, different ionizing flux as well as different temperatures and densities of the cold gas. We find a clear correlation between the initial state of the turbulent cloud and the final morphology and physical properties of the structures adjacent to the HII region. From the simulations we are able to derive a criterion for the formation of pillar-like structures and thus the formation of cores and stars. Gravitational collapse occurs regularly on the tips of the structures. We also derive column densities and velocity profiles of our simulations and find these to be in very good agreement with the observations of trunks and cores. In addition, we investigate the further evolution of the pillars once the massive star explodes. This leads to a supernova triggered scenario for the formation of our Solar System.

  8. Ionizing radiation and heart risks.

    PubMed

    Bhattacharya, Souparno; Asaithamby, Aroumougame

    2016-10-01

    Cardiovascular disease and cancer are the two leading causes of morbidity and mortality worldwide. As advancements in radiation therapy (RT) have significantly increased the number of cancer survivors, the risk of radiation-induced cardiovascular disease (RICD) in this group is a growing concern. Recent epidemiological data suggest that accidental or occupational exposure to low dose radiation, in addition to therapeutic ionizing radiation, can result in cardiovascular complications. The progression of radiation-induced cardiotoxicity often takes years to manifest but is also multifaceted, as the heart may be affected by a variety of pathologies. The risk of cardiovascular disease development in RT cancer survivors has been known for 40 years and several risk factors have been identified in the last two decades. However, most of the early work focused on clinical symptoms and manifestations, rather than understanding cellular processes regulating homeostatic processes of the cardiovascular system in response to radiation. Recent studies have suggested that a different approach may be needed to refute the risk of cardiovascular disease following radiation exposure. In this review, we will focus on how different radiation types and doses may induce cardiovascular complications, highlighting clinical manifestations and the mechanisms involved in the pathophysiology of radiation-induced cardiotoxicity. We will finally discuss how current and future research on heart development and homeostasis can help reduce the incidence of RICD.

  9. A simultaneous determination method for 5-fluorouracil and its metabolites in human plasma with linear range adjusted by in-source collision-induced dissociation using hydrophilic interaction liquid chromatography-electrospray ionization-tandem mass spectrometry.

    PubMed

    Ishii, Hideaki; Shimada, Miki; Yamaguchi, Hiroaki; Mano, Nariyasu

    2016-11-01

    We applied a new technique for quantitative linear range shift using in-source collision-induced dissociation (CID) to complex biological fluids to demonstrate its utility. The technique was used in a simultaneous quantitative determination method of 5-fluorouracil (5-FU), an anticancer drug for various solid tumors, and its metabolites in human plasma by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS). To control adverse effects after administration of 5-FU, it is important to monitor the plasma concentration of 5-FU and its metabolites; however, no simultaneous determination method has yet been reported because of vastly different physical and chemical properties of compounds. We developed a new analytical method for simultaneously determining 5-FU and its metabolites in human plasma by LC/ESI-MS/MS coupled with the technique for quantitative linear range shift using in-source CID. Hydrophilic interaction liquid chromatography using a stationary phase with zwitterionic functional groups, phosphorylcholine, was suitable for separation of 5-FU from its nucleoside and interfering endogenous materials. The addition of glycerin into acetonitrile-rich eluent after LC separation improved the ESI-MS response of high polar analytes. Based on the validation results, linear range shifts by in-source CID is the reliable technique even with complex biological samples such as plasma. Copyright © 2016 John Wiley & Sons Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Determination of 2-, 3-, 4-methylpentanoic and cyclohexanecarboxylic acids in wine: development of a selective method based on solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry and its application to different wines and alcoholic beverages.

    PubMed

    Gracia-Moreno, Elisa; Lopez, Ricardo; Ferreira, Vicente

    2015-02-13

    A method to analyse 2-methylpentanoic, 3-methylpentanoic and 4-methylpentanoic acids as well as cyclohexanecarboxylic acid has been developed and applied to wine and other alcoholic beverages. Selective isolation with solid phase extraction, derivatization with 2,3,4,5,6-pentafluorobenzyl bromide at room temperature for 30 minutes, and further analysis by gas chromatography-mass spectrometry in negative chemical ionization mode provides detection limits between 0.4 and 2.4 ng/L. Good linearity up to 3.6 μg/L, satisfactory reproducibility (RSD<10%) and signal recovery of around 100% represent a robust method of analysis. Concentration data of these analytes in wine and other alcoholic beverages are reported for the first time. The levels found ranged from the method detection limits to 2630 ng/L, 2040 ng/L and 3810 ng/L for 2-, 3- and 4-methylpentanoic acids, respectively, and to 1780 ng/L for cyclohexanecarboxylic acid. There are significant differences depending on the type of wine or beverage. Distilled beverages, beer and aged wines have higher contents in methylpentanoic and cyclohexanecarboxylic acids.

  11. A validated method for the determination of nicotine, cotinine, trans-3'-hydroxycotinine, and norcotinine in human plasma using solid-phase extraction and liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry.

    PubMed

    Kim, Insook; Huestis, Marilyn A

    2006-06-01

    A liquid chromatographic-mass spectrometric method for the simultaneous determination of nicotine, cotinine, trans-3'-hydroxycotinine, and norcotinine in human plasma was developed and validated. Analytes and deuterated internal standards were extracted from human plasma using solid-phase extraction and analyzed by liquid chromatography/atmospheric pressure chemical ionization-mass spectrometric detection with selected ion monitoring (SIM). Limits of detection and quantification were 1.0 and 2.5 ng/ml, respectively, for all analytes. Linearity ranged from 2.5 to 500 ng/ml of human plasma using a weighting factor of 1/x; correlation coefficients for the calibration curves were > 0.99. Intra- and inter-assay precision and accuracy were < 15.0%. Recoveries were 108.2-110.8% nicotine, 95.8-108.7% cotinine, 90.5-99.5% trans-3'-hydroxycotinine, and 99.5-109.5% norcotinine. The method was also partially validated in bovine serum, owing to the difficulty of obtaining nicotine-free human plasma for the preparation of calibrators and quality control (QC) samples. This method proved to be robust and accurate for the quantification of nicotine, cotinine, trans-3'-hydroxycotinine, and norcotinine in human plasma collected in clinical studies of acute nicotine effects on brain activity and on the development of neonates of maternal smokers.

  12. Effective novel dissociation methods for intact protein: heat-assisted nozzle-skimmer collisionally induced dissociation and infrared multiphoton dissociation using a Fourier transform ion cyclotron resonance mass spectrometer equipped with a micrometal electrospray ionization emitter.

    PubMed

    Yamada, Naoyuki; Suzuki, Ei-Ichiro; Hirayama, Kazuo

    2006-01-01

    Heating of a nano-electrospray ionization (nanoESI) source can improve the dissociation efficiency of collisionally induced dissociation (CID) methods, such as nozzle-skimmer CID (NS-CID) and infrared multiphoton dissociation (IRMPD), for large biomolecule fragmentation. A metal nanoESI emitter was used due to its resistance to heating above 250 degrees C. This novel method for the dissociation of large biomolecular ions is termed "heat-assisted NS-CID" (HANS-CID) or "heat-assisted IRMPD" (HA-IRMPD). Multiple charged nonreduced protein ions (8.6 Da ubiquitin, 14 kDa lysozyme, and 67 kDa bovine serum albumin) were directly dissociated by HANS-CID and HA-IRMPD to effectively yield fragment ions that could be assigned. The fragment ions of ubiquitin by HANS-CID can be analyzed by tandem mass spectrometry (MS/MS) using sustained off-resonance irradiation CID (SORI-CID) and IRMPD. In addition, a native large protein, immunoglobulin G (IgG, 150 kDa), was efficiently dissociated by HA-IRMPD. The product ions that were obtained reflected the domain structure of IgG. However, these product ions of IgG and lysozyme were not dissociated by MS/MS using the same heating energetic methods such as IRMPD and SORI-CID.

  13. Neonization method for stopping, mean excitation energy, straggling, and for total and differential ionization cross sections of CH4, NH3, H2O and FH by impact of heavy projectiles

    NASA Astrophysics Data System (ADS)

    Montanari, C. C.; Miraglia, J. E.

    2014-01-01

    We propose a neonization method to deal with molecules composed by hydrides of the second row of the periodic table of elements: CH4, NH3, OH2 and FH. This method describes these ten-electron molecules as dressed atoms in a pseudo-spherical potential. We test it by covering most of the inelastic collisional magnitudes of experimental interest: ionization cross sections (total, single and double differential), stopping power, energy-loss straggling and mean excitation energy. To this end, the neonization method has been treated with different collisional formalisms, such as the continuum-distorted-wave-eikonal-initial-state, the first order Born, and the shell-wise local plasma approximations. We show that the present model reproduces the different empirical values with high reliability in the intermediate to high-energy region. We also include the expansion of the spherical wave functions in terms of Slater-type orbitals and the analytic expression for the spherical potentials. This makes it possible in the future to tackle present neonization strategy with other collisional models.

  14. Identification of Gram-positive cocci by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry: comparison of different preparation methods and implementation of a practical algorithm for routine diagnostics.

    PubMed

    Schulthess, Bettina; Brodner, Katharina; Bloemberg, Guido V; Zbinden, Reinhard; Böttger, Erik C; Hombach, Michael

    2013-06-01

    This study compared three sample preparation methods (direct transfer, the direct transfer-formic acid method with on-target formic acid treatment, and ethanol-formic acid extraction) for the identification of Gram-positive cocci with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A total of 156 Gram-positive cocci representing the clinically most important genera, Aerococcus, Enterococcus, Staphylococcus, and Streptococcus, as well as more rare genera, such as Gemella and Granulicatella, were analyzed using a Bruker MALDI Biotyper. The rate of correct genus-level identifications was approximately 99% for all three sample preparation methods. The species identification rate was significantly higher for the direct transfer-formic acid method and ethanol-formic acid extraction (both 77.6%) than for direct transfer (64.1%). Using direct transfer-formic acid compared to direct transfer, the total time to result was increased by 22.6%, 16.4%, and 8.5% analyzing 12, 48, and 96 samples per run, respectively. In a subsequent prospective study, 1,619 clinical isolates of Gram-positive cocci were analyzed under routine conditions by MALDI-TOF MS, using the direct transfer-formic acid preparation, and by conventional biochemical methods. For 95.6% of the isolates, a congruence between conventional and MALDI-TOF MS identification was observed. Two major limitations were found using MALDI-TOF MS: the differentiation of members of the Streptococcus mitis group and the identification of Streptococcus dysgalactiae. The Bruker MALDI Biotyper system using the direct transfer-formic acid sample preparation method was shown to be a highly reliable tool for the identification of Gram-positive cocci. We here suggest a practical algorithm for the clinical laboratory combining MALDI-TOF MS with phenotypic and molecular methods.

  15. Multiple-ionization of xenon atoms by positron impact

    NASA Technical Reports Server (NTRS)

    Kruse, Georg; Quermann, Andreas; Raith, Wilhelm; Sinapius, Guenther

    1990-01-01

    Previously the cross sections were measured for positronium formation and single ionization by positron impact for He and H2. With the same apparatus, slightly modified, the single and multiple ionization of xenon is now investigated. The principle of the method is the detection of ion and positron in time correlation which allows the discrimination of positronium formation (whereby the positron vanishes) and the destinction of single, double and triple impact ionization (which lead to different ion flight times from the gas target to the ion detector). By using secondary electrons from the positron moderator, similar measurements were performed on electron impact ionization. By comparing with literature values for electron multiple ionization cross sections, the detection-probability ratios were determined for the differently charged ions.

  16. Optical Imaging of Ionizing Radiation from Clinical Sources.

    PubMed

    Shaffer, Travis M; Drain, Charles Michael; Grimm, Jan

    2016-11-01

    Nuclear medicine uses ionizing radiation for both in vivo diagnosis and therapy. Ionizing radiation comes from a variety of sources, including x-rays, beam therapy, brachytherapy, and various injected radionuclides. Although PET and SPECT remain clinical mainstays, optical readouts of ionizing radiation offer numerous benefits and complement these standard techniques. Furthermore, for ionizing radiation sources that cannot be imaged using these standard techniques, optical imaging offers a unique imaging alternative. This article reviews optical imaging of both radionuclide- and beam-based ionizing radiation from high-energy photons and charged particles through mechanisms including radioluminescence, Cerenkov luminescence, and scintillation. Therapeutically, these visible photons have been combined with photodynamic therapeutic agents preclinically for increasing therapeutic response at depths difficult to reach with external light sources. Last, new microscopy methods that allow single-cell optical imaging of radionuclides are reviewed. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  17. Optical Imaging of Ionizing Radiation from Clinical Sources

    PubMed Central

    Shaffer, Travis M.; Drain, Charles Michael

    2016-01-01

    Nuclear medicine uses ionizing radiation for both in vivo diagnosis and therapy. Ionizing radiation comes from a variety of sources, including x-rays, beam therapy, brachytherapy, and various injected radionuclides. Although PET and SPECT remain clinical mainstays, optical readouts of ionizing radiation offer numerous benefits and complement these standard techniques. Furthermore, for ionizing radiation sources that cannot be imaged using these standard techniques, optical imaging offers a unique imaging alternative. This article reviews optical imaging of both radionuclide- and beam-based ionizing radiation from high-energy photons and charged particles through mechanisms including radioluminescence, Cerenkov luminescence, and scintillation. Therapeutically, these visible photons have been combined with photodynamic therapeutic agents preclinically for increasing therapeutic response at depths difficult to reach with external light sources. Last, new microscopy methods that allow single-cell optical imaging of radionuclides are reviewed. PMID:27688469

  18. Mass analyzed threshold ionization (MATI) with VUV radiation

    NASA Astrophysics Data System (ADS)

    Kostko, Oleg; Kim, Sang Kyu; Wilson, Kevin R.; Leone, Stephen R.; Ahmed, Musahid

    2009-05-01

    Mass analyzed threshold ionization is a combination of threshold ionization spectroscopy with mass spectrometry. Similar to zero electron kinetic energy (ZEKE), MATI spectroscopy takes advantage of the field ionization of long lived high Rydberg states to obtain an ionization threshold and perform spectroscopy on the resulting cation. MATI at the synchrotron utilizing tunable VUV light opens up a novel way to perform spectroscopy on ions and improve the resolution in ionization energy determination in comparison with conventional photoionization efficiency curve measurements. This method is implemented at the Advanced Light Source and vibrationally-resolved MATI spectra for simple di- and polyatomic molecules (O2, N2, H2O, N2O, C2H2, and C6H6) are measured. This preliminary work allows us to test the applicability of MATI at a synchrotron and prepare for investigation of more complex systems such as mixtures of molecules, isomers and clusters.

  19. Signatures of bound-state-assisted nonsequential double ionization

    SciTech Connect

    Sukiasyan, Suren; McDonald, Chris; Van Vlack, Cole; Destefani, Carlos; Fennel, Thomas; Brabec, Thomas; Ivanov, Misha

    2009-07-15

    The time-dependent multiconfiguration Hartree method is optimized for intense laser dynamics and applied to nonsequential double ionization in a two-electron diatomic model molecule with two dimensions per electron. The efficiency of our method brings these calculations from the realm of large scale computation facilities to single processor machines. The resulting two-electron spectrum exhibits pronounced signatures from which the ionic bound states involved in nonsequential double ionization are retrieved with the help of a semiclassical model. A mechanism for the ionization dynamics is suggested.

  20. [Ionizing and non-ionizing radiation (comparative risk estimations)].

    PubMed

    Grigor'ev, Iu G

    2012-01-01

    The population has widely used mobile communication for already more than 15 years. It is important to note that the use of mobile communication has sharply changed the conditions of daily exposure of the population to EME We expose our brain daily for the first time in the entire civilization. The mobile phone is an open and uncontrollable source of electromagnetic radiation. The comparative risk estimation for the population of ionizing and non-ionizing radiation was carried out taking into account the real conditions of influence. Comparison of risks for the population of ionizing and non-ionizing radiation leads us to a conclusion that EMF RF exposure in conditions of wide use of mobile communication is potentially more harmful than ionizing radiation influence.