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Sample records for accurate mass determination

  1. Accurate Mass Determination of Amino Alcohols by Turboionspray/Time-of-Flight Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    GENG,Yu(耿昱); GUO,Yin-Long(郭寅龙); ZHAO,Shi-Min(赵士民); MA,Sheng-Ming(麻生明)

    2002-01-01

    Amino alcohols were studied by turboionspray/time-of-flight mass spectrometry (TIS/TOF-MS) with the aim of determining the accurate mass of their protonated molecule ions.Polyethylene glycol (PEG) was used as the internal reference.Compared with the theoretical values, all relative errors were less than 5×10-6. The effects of nozzle potential, nozzle temperature, acquisition rate etc. on accurate mass determination were also studied.

  2. An Accurate de novo Algorithm for Glycan Topology Determination from Mass Spectra.

    Science.gov (United States)

    Dong, Liang; Shi, Bing; Tian, Guangdong; Li, YanBo; Wang, Bing; Zhou, MengChu

    2015-01-01

    Determining the glycan topology automatically from mass spectra represents a great challenge. Existing methods fall into approximate and exact ones. The former including greedy and heuristic ones can reduce the computational complexity, but suffer from information lost in the procedure of glycan interpretation. The latter including dynamic programming and exhaustive enumeration are much slower than the former. In the past years, nearly all emerging methods adopted a tree structure to represent a glycan. They share such problems as repetitive peak counting in reconstructing a candidate structure. Besides, tree-based glycan representation methods often have to give different computational formulas for binary and ternary glycans. We propose a new directed acyclic graph structure for glycan representation. Based on it, this work develops a de novo algorithm to accurately reconstruct the tree structure iteratively from mass spectra with logical constraints and some known biosynthesis rules, by a single computational formula. The experiments on multiple complex glycans extracted from human serum show that the proposed algorithm can achieve higher accuracy to determine a glycan topology than prior methods without increasing computational burden.

  3. Accurate determination of silver nanoparticles in animal tissues by inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Veverková, Lenka [Regional Centre of Advanced Technologies and Materials, Department of Analytical Chemistry, Faculty of Science, Palacky University, 17.listopadu 12, CZ 771 46 Olomouc (Czech Republic); Hradilová, Šárka [Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17.listopadu 12, CZ 771 46 Olomouc (Czech Republic); Milde, David, E-mail: david.mlde@upol.cz [Regional Centre of Advanced Technologies and Materials, Department of Analytical Chemistry, Faculty of Science, Palacky University, 17.listopadu 12, CZ 771 46 Olomouc (Czech Republic); Panáček, Aleš [Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17.listopadu 12, CZ 771 46 Olomouc (Czech Republic); Skopalová, Jana [Regional Centre of Advanced Technologies and Materials, Department of Analytical Chemistry, Faculty of Science, Palacky University, 17.listopadu 12, CZ 771 46 Olomouc (Czech Republic); Kvítek, Libor [Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17.listopadu 12, CZ 771 46 Olomouc (Czech Republic); Petrželová, Kamila [Regional Centre of Advanced Technologies and Materials, Department of Analytical Chemistry, Faculty of Science, Palacky University, 17.listopadu 12, CZ 771 46 Olomouc (Czech Republic); National Reference Laboratory for Chemical Elements, Department of Residues in Kroměříž, State Veterinary Institute Olomouc, Hulínská 2286, CZ 767 60 Kroměříž (Czech Republic); and others

    2014-12-01

    This study examined recoveries of silver determination in animal tissues after wet digestion by inductively coupled plasma mass spectrometry. The composition of the mineralization mixture for microwave assisted digestion was optimized and the best recoveries were obtained for mineralization with HNO{sub 3} and addition of HCl promptly after digestion. The optimization was performed on model samples of chicken meat spiked with silver nanoparticles and a solution of ionic silver. Basic calculations of theoretical distribution of Ag among various silver-containing species were implemented and the results showed that most of the silver is in the form of soluble complexes AgCl{sub 2}{sup −} and AgCl{sub 3}{sup 2−} for the optimized composition of the mineralization mixture. Three animal tissue certified reference materials were then analyzed to verify the trueness and precision of the results. - Highlights: • We performed detailed optimization of microwave assisted digestion procedure of animal tissue used prior to Ag determination by ICP-MS. • We provide basic equilibrium calculations to give theoretical explanation of results from optimization of tested mineralization mixtures. • Results from method validation that was done by analysis of several matrix CRMs are presented.

  4. Multiclass semi-volatile compounds determination in wine by gas chromatography accurate time-of-flight mass spectrometry.

    Science.gov (United States)

    Rodríguez-Cabo, T; Rodríguez, I; Ramil, M; Silva, A; Cela, R

    2016-04-15

    The performance of gas chromatography (GC) with accurate, high resolution mass spectrometry (HRMS) for the determination of a group of 39 semi-volatile compounds related to wine quality (pesticide residues, phenolic off-flavours, phenolic pollutants and bioactive stilbenes) is investigated. Solid-phase extraction (SPE) was used as extraction technique, previously to acetylation (phenolic compounds) and dispersive liquid-liquid microextraction (DLLME) concentration. Compounds were determined by GC coupled to a quadrupole time-of-flight (QTOF) MS system through an electron ionization (EI) source. The final method attained limits of quantification (LOQs) at the very low ng mL(-1) level, covering the range of expected concentrations for target compounds in red and white wines. For 38 out of 39 compounds, performance of sample preparation and determination steps were hardly affected by the wine matrix; thus, accurate recoveries were achieved by using pseudo-external calibration. Levels of target compounds in a set of 25 wine samples are reported. The capabilities of the described approach for the post-run identification of species not considered during method development, without retention time information, are illustrated and discussed with selected examples of compounds from different classes.

  5. Accurate determination of peptide phosphorylation stoichiometry via automated diagonal capillary electrophoresis coupled with mass spectrometry: proof of principle.

    Science.gov (United States)

    Mou, Si; Sun, Liangliang; Dovichi, Norman J

    2013-11-19

    While reversible protein phosphorylation plays an important role in many cellular processes, simple and reliable measurement of the stoichiometry of phosphorylation can be challenging. This measurement is confounded by differences in the ionization efficiency of phosphorylated and unphosphorylated sites during analysis by mass spectrometry. Here, we demonstrate diagonal capillary electrophoresis-mass spectrometry for the accurate determination of this stoichiometry. Diagonal capillary electrophoresis is a two-dimensional separation method that incorporates an immobilized alkaline phosphatase microreactor at the distal end of the first capillary and employs identical electrophoretic separation modes in both dimensions. The first dimension is used to separate a mixture of the phosphorylated and unphosphorylated forms of a peptide. Fractions are parked in the reactor where they undergo complete dephosphorylation. The products are then periodically transferred to the second capillary and analyzed by mass spectrometry (MS). Because the phosphorylated and unphosphorylated forms differ in charge, they are well resolved in the first dimension separation. Because the unphosphorylated and dephosphorylated peptides are identical, there is no bias in ionization efficiency, and phosphorylation stoichiometry can be determined by the ratio of the signal of the two forms. A calibration curve was generated from mixtures of a phosphorylated standard peptide and its unphosphorylated form, prepared in a bovine serum albumin tryptic digest. This proof of principle experiment demonstrated a linear response across nearly 2 orders of magnitude in stoichiometry.

  6. Development of an Isotope-Dilution Liquid Chromatography/Mass Spectrometric Method for the Accurate Determination of Acetaminophen in Tablets

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hyun Ju; Kim, Byung Joo; Lee, Joon Hee; Hwang, Eui Jin [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2010-12-15

    Acetaminophen (N-acetyl-p-aminophenol) is one of the most popular analgesic and antipyretic drugs. An isotope dilution mass spectrometric method based on LC/MS was developed as a candidate reference method for the accurate determination of acetaminophen in pharmaceutical product. After spiking an isotope labeled acetaminophen (acetyl-{sup 13}C{sub 2}, {sup 15}Nacetaminophen) as an internal standard, tablet extracts were analyzed by LC/MS in a selected reaction monitoring (SRM) mode to detect ions at m/z 152→110 and m/z 155→111 for acetaminophen and acetyl-{sup 13}C{sub 2}, {sup 15}N-acetaminophen, respectively. The repeatability and reproducibility of the developed ID/LC-MS method were tested for the validation and assessment of metrological quality of the method.

  7. Accurate determination of selected pesticides in soya beans by liquid chromatography coupled to isotope dilution mass spectrometry.

    Science.gov (United States)

    Huertas Pérez, J F; Sejerøe-Olsen, B; Fernández Alba, A R; Schimmel, H; Dabrio, M

    2015-05-01

    A sensitive, accurate and simple liquid chromatography coupled with mass spectrometry method for the determination of 10 selected pesticides in soya beans has been developed and validated. The method is intended for use during the characterization of selected pesticides in a reference material. In this process, high accuracy and appropriate uncertainty levels associated to the analytical measurements are of utmost importance. The analytical procedure is based on sample extraction by the use of a modified QuEChERS (quick, easy, cheap, effective, rugged, safe) extraction and subsequent clean-up of the extract with C18, PSA and Florisil. Analytes were separated on a C18 column using gradient elution with water-methanol/2.5 mM ammonium acetate mobile phase, and finally identified and quantified by triple quadrupole mass spectrometry in the multiple reaction monitoring mode (MRM). Reliable and accurate quantification of the analytes was achieved by means of stable isotope-labelled analogues employed as internal standards (IS) and calibration with pure substance solutions containing both, the isotopically labelled and native compounds. Exceptions were made for thiodicarb and malaoxon where the isotopically labelled congeners were not commercially available at the time of analysis. For the quantification of those compounds methomyl-(13)C2(15)N and malathion-D10 were used respectively. The method was validated according to the general principles covered by DG SANCO guidelines. However, validation criteria were set more stringently. Mean recoveries were in the range of 86-103% with RSDs lower than 8.1%. Repeatability and intermediate precision were in the range of 3.9-7.6% and 1.9-8.7% respectively. LODs were theoretically estimated and experimentally confirmed to be in the range 0.001-0.005 mg kg(-1) in the matrix, while LOQs established as the lowest spiking mass fractionation level were in the range 0.01-0.05 mg kg(-1). The method reliably identifies and quantifies the

  8. Innovations in Mass Spectrometry for Precise and Accurate Isotope Ratio Determination from Very Small Analyte Quantities (Invited)

    Science.gov (United States)

    Lloyd, N. S.; Bouman, C.; Horstwood, M. S.; Parrish, R. R.; Schwieters, J. B.

    2010-12-01

    This presentation describes progress in mass spectrometry for analysing very small analyte quantities, illustrated by example applications from nuclear forensics. In this challenging application, precise and accurate (‰) uranium isotope ratios are required from 1 - 2 µm diameter uranium oxide particles, which comprise less than 40 pg of uranium. Traditionally these are analysed using thermal ionisation mass spectrometry (TIMS), and more recently using secondary ionisation mass spectrometry (SIMS). Multicollector inductively-coupled plasma mass spectrometry (MC-ICP-MS) can offer higher productivity compared to these techniques, but is traditionally limited by low efficiency of analyte utilisation (sample through to ion detection). Samples can either be introduced as a solution, or sampled directly from solid using laser ablation. Large multi-isotope ratio datasets can help identify provenance and intended use of anthropogenic uranium and other nuclear materials [1]. The Thermo Scientific NEPTUNE Plus (Bremen, Germany) with ‘Jet Interface’ option offers unparalleled MC-ICP-MS sensitivity. An analyte utilisation of c. 4% has previously been reported for uranium [2]. This high-sensitivity configuration utilises a dry high-capacity (100 m3/h) interface pump, special skimmer and sampler cones and a desolvating nebuliser system. Coupled with new acquisition methodologies, this sensitivity enhancement makes possible the analysis of micro-particles and small sample volumes at higher precision levels than previously achieved. New, high-performance, full-size and compact discrete dynode secondary electron multipliers (SEM) exhibit excellent stability and linearity over a large dynamic range and can be configured to simultaneously measure all of the uranium isotopes. Options for high abundance-sensitivity filters on two ion beams are also available, e.g. for 236U and 234U. Additionally, amplifiers with high ohm (1012 - 1013) feedback resistors have been developed to

  9. Accurate determination of ⁴¹Ca concentrations in spent resins from the nuclear industry by accelerator mass spectrometry.

    Science.gov (United States)

    Nottoli, Emmanuelle; Bourlès, Didier; Bienvenu, Philippe; Labet, Alexandre; Arnold, Maurice; Bertaux, Maité

    2013-12-01

    The radiological characterisation of nuclear waste is essential for managing storage sites. Determining the concentration of Long-Lived RadioNuclides (LLRN) is fundamental for their long-term management. This paper focuses on the measurement of low (41)Ca concentrations in ions exchange resins used for primary fluid purification in Pressurised Water Reactors (PWR). (41)Ca concentrations were successfully measured by Accelerator Mass Spectrometry (AMS) after the acid digestion of resin samples, followed by radioactive decontamination and isobaric suppression through successive hydroxide, carbonate, nitrate and final CaF2 precipitations. Measured (41)Ca concentrations ranged from 0.02 to 0.03 ng/g, i.e. from 0.06 to 0.09 Bq/g. The (41)Ca/(60)Co activity ratios obtained were remarkably reproducible and in good agreement with the current ratio used for resins management.

  10. Accurate determination of antenna directivity

    DEFF Research Database (Denmark)

    Dich, Mikael

    1997-01-01

    The derivation of a formula for accurate estimation of the total radiated power from a transmitting antenna for which the radiated power density is known in a finite number of points on the far-field sphere is presented. The main application of the formula is determination of directivity from power......-pattern measurements. The derivation is based on the theory of spherical wave expansion of electromagnetic fields, which also establishes a simple criterion for the required number of samples of the power density. An array antenna consisting of Hertzian dipoles is used to test the accuracy and rate of convergence...

  11. Accurate determination of ochratoxin A in Korean fermented soybean paste by isotope dilution-liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Ahn, Seonghee; Lee, Suyoung; Lee, Joonhee; Kim, Byungjoo

    2016-01-01

    Ochratoxin A (OTA), a naturally occurring mycotoxin, has been frequently detected in doenjang, a traditional fermented soybean paste, when it is fermented under improper conditions. Reliable screening of OTA in traditional fermented soybean paste (doenjang) is a special food-safety issue in Korea. Our laboratory, the National Metrology Institute of Korea, established an isotope dilution-liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) method as a higher-order reference method to be used for SI-traceable value-assignment of OTA in certified reference materials (CRMs). (13)C20-OTA was used as an internal standard. Sample preparation conditions and LC/MS measurement parameters were optimised for this purpose. The analytical method was validated by measuring samples fortified with OTA at various levels. Repeatability and reproducibility studies showed that the ID-LC/MS/MS method is reliable and reproducible within 2% relative standard deviation. The analytical method was applied to determine OTA in various commercial doenjang products and home-made doenjang products.

  12. Quantitative LC-MS of polymers: determining accurate molecular weight distributions by combined size exclusion chromatography and electrospray mass spectrometry with maximum entropy data processing.

    Science.gov (United States)

    Gruendling, Till; Guilhaus, Michael; Barner-Kowollik, Christopher

    2008-09-15

    We report on the successful application of size exclusion chromatography (SEC) combined with electrospray ionization mass spectrometry (ESI-MS) and refractive index (RI) detection for the determination of accurate molecular weight distributions of synthetic polymers, corrected for chromatographic band broadening. The presented method makes use of the ability of ESI-MS to accurately depict the peak profiles and retention volumes of individual oligomers eluting from the SEC column, whereas quantitative information on the absolute concentration of oligomers is obtained from the RI-detector only. A sophisticated computational algorithm based on the maximum entropy principle is used to process the data gained by both detectors, yielding an accurate molecular weight distribution, corrected for chromatographic band broadening. Poly(methyl methacrylate) standards with molecular weights up to 10 kDa serve as model compounds. Molecular weight distributions (MWDs) obtained by the maximum entropy procedure are compared to MWDs, which were calculated by a conventional calibration of the SEC-retention time axis with peak retention data obtained from the mass spectrometer. Comparison showed that for the employed chromatographic system, distributions below 7 kDa were only weakly influenced by chromatographic band broadening. However, the maximum entropy algorithm could successfully correct the MWD of a 10 kDa standard for band broadening effects. Molecular weight averages were between 5 and 14% lower than the manufacturer stated data obtained by classical means of calibration. The presented method demonstrates a consistent approach for analyzing data obtained by coupling mass spectrometric detectors and concentration sensitive detectors to polymer liquid chromatography.

  13. Accurate determination of Curium and Californium isotopic ratios by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) in 248Cm samples for transmutation studies

    Energy Technology Data Exchange (ETDEWEB)

    Gourgiotis, A.; Isnard, H.; Aubert, M.; Dupont, E.; AlMahamid, I.; Cassette, P.; Panebianco, S.; Letourneau, A.; Chartier, F.; Tian, G.; Rao, L.; Lukens, W.

    2011-02-01

    The French Atomic Energy Commission has carried out several experiments including the mini-INCA (INcineration of Actinides) project for the study of minor-actinide transmutation processes in high intensity thermal neutron fluxes, in view of proposing solutions to reduce the radiotoxicity of long-lived nuclear wastes. In this context, a Cm sample enriched in {sup 248}Cm ({approx}97 %) was irradiated in thermal neutron flux at the High Flux Reactor (HFR) of the Laue-Langevin Institute (ILL). This work describes a quadrupole ICP-MS (ICP-QMS) analytical procedure for precise and accurate isotopic composition determination of Cm before sample irradiation and of Cm and Cf after sample irradiation. The factors that affect the accuracy and reproducibility of isotopic ratio measurements by ICP-QMS, such as peak centre correction, detector dead time, mass bias, abundance sensitivity and hydrides formation, instrumental background, and memory blank were carefully evaluated and corrected. Uncertainties of the isotopic ratios, taking into account internal precision of isotope ratio measurements, peak tailing, and hydrides formations ranged from 0.3% to 1.3%. This uncertainties range is quite acceptable for the nuclear data to be used in transmutation studies.

  14. Accurate mass measurements on neutron-deficient krypton isotopes

    CERN Document Server

    Rodríguez, D; Äystö, J; Beck, D

    2006-01-01

    The masses of $^{72–78,80,82,86}$Kr were measured directly with the ISOLTRAP Penning trap mass spectrometer at ISOLDE/CERN. For all these nuclides, the measurements yielded mass uncertainties below 10 keV. The ISOLTRAP mass values for $^{72–75}$Kr being more precise than the previous results obtained by means of other techniques, and thus completely determine the new values in the Atomic-Mass Evaluation. Besides the interest of these masses for nuclear astrophysics, nuclear structure studies, and Standard Model tests, these results constitute a valuable and accurate input to improve mass models. In this paper, we present the mass measurements and discuss the mass evaluation for these Kr isotopes.

  15. Accurate mass measurements on neutron-deficient krypton isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, D. [GSI, Planckstrasse 1, 64291 Darmstadt (Germany)]. E-mail: rodriguez@lpccaen.in2p3.fr; Audi, G. [CSNSM-IN2P3-CNRS, 91405 Orsay-Campus(France); Aystoe, J. [University of Jyvaeskylae, Department of Physics, P.O. Box 35, 40351 Jyvaeskylae (Finland); Beck, D. [GSI, Planckstrasse 1, 64291 Darmstadt (Germany); Blaum, K. [GSI, Planckstrasse 1, 64291 Darmstadt (Germany); Institute of Physics, University of Mainz, Staudingerweg 7, 55128 Mainz (Germany); Bollen, G. [NSCL, Michigan State University, East Lansing, MI 48824-1321 (United States); Herfurth, F. [GSI, Planckstrasse 1, 64291 Darmstadt (Germany); Jokinen, A. [University of Jyvaeskylae, Department of Physics, P.O. Box 35, 40351 Jyvaeskylae (Finland); Kellerbauer, A. [CERN, Division EP, 1211 Geneva 23 (Switzerland); Kluge, H.-J. [GSI, Planckstrasse 1, 64291 Darmstadt (Germany); University of Heidelberg, 69120 Heidelberg (Germany); Kolhinen, V.S. [University of Jyvaeskylae, Department of Physics, P.O. Box 35, 40351 Jyvaeskylae (Finland); Oinonen, M. [Helsinki Institute of Physics, P.O. Box 64, 00014 University of Helsinki (Finland); Sauvan, E. [Institute of Physics, University of Mainz, Staudingerweg 7, 55128 Mainz (Germany); Schwarz, S. [NSCL, Michigan State University, East Lansing, MI 48824-1321 (United States)

    2006-04-17

    The masses of {sup 72-78,80,82,86}Kr were measured directly with the ISOLTRAP Penning trap mass spectrometer at ISOLDE/CERN. For all these nuclides, the measurements yielded mass uncertainties below 10 keV. The ISOLTRAP mass values for {sup 72-75}Kr outweighed previous results obtained by means of other techniques, and thus completely determine the new values in the Atomic-Mass Evaluation. Besides the interest of these masses for nuclear astrophysics, nuclear structure studies, and Standard Model tests, these results constitute a valuable and accurate input to improve mass models. In this paper, we present the mass measurements and discuss the mass evaluation for these Kr isotopes.

  16. Laboratory Building for Accurate Determination of Plutonium

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The accurate determination of plutonium is one of the most important assay techniques of nuclear fuel, also the key of the chemical measurement transfer and the base of the nuclear material balance. An

  17. Accurate determination of ¹²⁹I concentrations and ¹²⁹I/¹³⁷Cs ratios in spent nuclear resins by Accelerator Mass Spectrometry.

    Science.gov (United States)

    Nottoli, Emmanuelle; Bienvenu, Philippe; Labet, Alexandre; Bourlès, Didier; Arnold, Maurice; Bertaux, Maité

    2014-04-01

    Determining long-lived radionuclide concentrations in radioactive waste has fundamental implications for the long-term management of storage sites. This paper focuses on the measurement of low (129)I contents in ion exchange resins used for primary fluid purification in Pressurised Water Reactors (PWR). Iodine-129 concentrations were successfully determined using Accelerator Mass Spectrometry (AMS) following a chemical procedure which included (1) acid digestion of resin samples in HNO3/HClO4, (2) radioactive decontamination by selective iodine extraction using a new chromatographic resin (CL Resin), and (3) AgI precipitation. Measured (129)I concentrations ranged from 4 to 12 ng/g, i.e. from 0.03 to 0.08 Bq/g. The calculation of (129)I/(137)Cs activity ratios used for routine waste management produced values in agreement with the few available data for PWR resin samples.

  18. Accurate determination of characteristic relative permeability curves

    Science.gov (United States)

    Krause, Michael H.; Benson, Sally M.

    2015-09-01

    A recently developed technique to accurately characterize sub-core scale heterogeneity is applied to investigate the factors responsible for flowrate-dependent effective relative permeability curves measured on core samples in the laboratory. The dependency of laboratory measured relative permeability on flowrate has long been both supported and challenged by a number of investigators. Studies have shown that this apparent flowrate dependency is a result of both sub-core scale heterogeneity and outlet boundary effects. However this has only been demonstrated numerically for highly simplified models of porous media. In this paper, flowrate dependency of effective relative permeability is demonstrated using two rock cores, a Berea Sandstone and a heterogeneous sandstone from the Otway Basin Pilot Project in Australia. Numerical simulations of steady-state coreflooding experiments are conducted at a number of injection rates using a single set of input characteristic relative permeability curves. Effective relative permeability is then calculated from the simulation data using standard interpretation methods for calculating relative permeability from steady-state tests. Results show that simplified approaches may be used to determine flowrate-independent characteristic relative permeability provided flow rate is sufficiently high, and the core heterogeneity is relatively low. It is also shown that characteristic relative permeability can be determined at any typical flowrate, and even for geologically complex models, when using accurate three-dimensional models.

  19. On accurate determination of contact angle

    Science.gov (United States)

    Concus, P.; Finn, R.

    1992-01-01

    Methods are proposed that exploit a microgravity environment to obtain highly accurate measurement of contact angle. These methods, which are based on our earlier mathematical results, do not require detailed measurement of a liquid free-surface, as they incorporate discontinuous or nearly-discontinuous behavior of the liquid bulk in certain container geometries. Physical testing is planned in the forthcoming IML-2 space flight and in related preparatory ground-based experiments.

  20. Mass spectrometry based protein identification with accurate statistical significance assignment

    OpenAIRE

    Alves, Gelio; Yu, Yi-Kuo

    2014-01-01

    Motivation: Assigning statistical significance accurately has become increasingly important as meta data of many types, often assembled in hierarchies, are constructed and combined for further biological analyses. Statistical inaccuracy of meta data at any level may propagate to downstream analyses, undermining the validity of scientific conclusions thus drawn. From the perspective of mass spectrometry based proteomics, even though accurate statistics for peptide identification can now be ach...

  1. Absolute Neutrino Mass Determination

    CERN Document Server

    Päs, H

    2001-01-01

    We discuss four approaches to the determination of absolute neutrino mass. These are the measurement of the zero-neutrino double beta decay rate, of the tritium decay end-point spectrum, of the cosmic ray spectrum above the GZK cutoff, and the cosmological measurement of the power spectrum governing the CMB and large scale structure. The first two approaches are sensitive to the mass eigenstates coupling to the electron neutrino, whereas the latter two are sensitive to the heavy component of the cosmic neutrino background. All mass eigenstates are related by the $\\Delta m^2$'s inferred from neutrino oscillation data. Consequently, the potential for absolute mass determination of each of the four approaches is correlated with the other three, in ways that we point out.

  2. Accurate determination of serum ASAT isoenzymes.

    Science.gov (United States)

    Konttinen, A; Ojala, K

    1978-01-01

    An improved electrophoretic modification for measuring aspartate aminotransferase (ASAT) isoenzymes is presented. This method fulfils the clinical requirements for sensitivity and allows the detection of 1 U/l mitochondria ASAT activity at 25 degree C. The procedure is relatively simple, requiring about one hour for a series of 8 determinations. Mitochondrial ASAT activity was found in all patients suffering from acute myocardial infarction pathological activity was observed for several days longer than that of total serum ASAT enzyme. None of the 25 healthy people studied had mitochondrial ASAT in their serum.

  3. Accurate, Empirical Radii and Masses of Planets with Gaia Parallaxes

    CERN Document Server

    Stassun, Keivan G; Gaudi, B Scott

    2016-01-01

    We present new, empirical measurements of the radii of 132 stars that host transiting planets. These stellar radii are determined using only direct observables---the bolometric flux at Earth, the stellar effective temperature, and the parallax newly provided by the Gaia first data release---and thus are virtually model independent, extinction being the only free parameter. We also determine each star's mass using our newly determined radius and the stellar density, itself a virtually model independent quantity from the previously published transit analysis. The newly determined stellar radii and masses are in turn used to re-determine the transiting planet radii and masses, once again using only direct observables. The uncertainties on the stellar radii and masses are typically 7% and 25%, respectively, and the resulting uncertainties on the planet radii and masses are 8% and 20%, respectively. These accuracies are generally larger than the previously published model-dependent precisions of 5% and 6% on the p...

  4. Ion Mass Determination

    DEFF Research Database (Denmark)

    2010-01-01

    An apparatus (100) is described for determining the mass of ions, the apparatus configured to hold a plasma (101 ) having a plasma potential. The apparatus (100) comprises an electrode (102) having a surface extending in a surface plane and an insulator (104) interfacing with the electrode (102...... to provide a magnetic field (B) across at least part of the curved potential distribution in the plasma surrounding the electrode (102). An ion impact detector (108) is configured to detect impacts of ions arriving at the electrode (102), the detecting comprising detecting of locations of the impacts......, and a processing unit (108) configured to interpret the detected impact locations in terms of the mass of the impacting ions....

  5. Improving the mass determination of Galactic Cepheids

    CERN Document Server

    Bono, G; Marconi, M; Fouqué, P; Caputo, F

    2001-01-01

    We have selected a sample of Galactic Cepheids for which accurate estimates of radii, distances, and photometric parameters are available. The comparison between their pulsation masses, based on new Period-Mass-Radius (PMR) relations, and their evolutionary masses, based on both optical and NIR Color-Magnitude (CM) diagrams, suggests that pulsation masses are on average of the order of 10% smaller than the evolutionary masses. Current pulsation masses show, at fixed radius, a strongly reduced dispersion when compared with values published in literature.The increased precision in the pulsation masses is due to the fact that our predicted PMR relations based on nonlinear, convective Cepheid models present smaller standard deviations than PMR relations based on linear models. At the same time, the empirical radii of our Cepheid sample are typically accurate at the 5% level. Our evolutionary mass determinations are based on stellar models constructed by neglecting the effect of mass-loss during the He burning pha...

  6. Highly Accurate Sensor for High-Purity Oxygen Determination Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this STTR effort, Los Gatos Research (LGR) and the University of Wisconsin (UW) propose to develop a highly-accurate sensor for high-purity oxygen determination....

  7. Accurate Low-Mass Stellar Models of KOI-126

    CERN Document Server

    Feiden, Gregory A; Dotter, Aaron

    2011-01-01

    The recent discovery of an eclipsing hierarchical triple system with two low-mass stars in a close orbit (KOI-126) by Carter et al. (2011) appeared to reinforce the evidence that theoretical stellar evolution models are not able to reproduce the observational mass-radius relation for low-mass stars. We present a set of stellar models for the three stars in the KOI-126 system that show excellent agreement with the observed radii. This agreement appears to be due to the equation of state implemented by our code. A significant dispersion in the observed mass-radius relation for fully convective stars is demonstrated; indicative of the influence of physics currently not incorporated in standard stellar evolution models. We also predict apsidal motion constants for the two M-dwarf companions. These values should be observationally determined to within 1% by the end of the Kepler mission.

  8. A sensitive and accurate method for the determination of perfluoroalkyl and polyfluoroalkyl substances in human serum using a high performance liquid chromatography-online solid phase extraction-tandem mass spectrometry.

    Science.gov (United States)

    Yu, Chang Ho; Patel, Bhupendra; Palencia, Marilou; Fan, Zhihua Tina

    2017-01-13

    A selective, sensitive, and accurate analytical method for the measurement of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in human serum, utilizing LC-MS/MS (liquid chromatography-tandem mass spectrometry), was developed and validated according to the Centers for Disease Control and Prevention (CDC) guidelines for biological sample analysis. Tests were conducted to determine the optimal analytical column, mobile phase composition and pH, gradient program, and cleaning procedure. The final analytical column selected for analysis was an extra densely bonded silica-packed reverse-phase column (Agilent XDB-C8, 3.0×100mm, 3.5μm). Mobile phase A was an aqueous buffer solution containing 10mM ammonium acetate (pH=4.3). Mobile phase B was a mixture of methanol and acetonitrile (1:1, v/v). The gradient program was programmed by initiating a fast elution (%B, from 40 to 65%) between 1.0 and 1.5min, followed by a slow elution (%B: 65-80%) in the period of 1.5-7.5min. The cleanup procedures were augmented by cleaning with (1) various solvents (isopropyl alcohol, methanol, acetonitrile, and reverse osmosis-purified water); (2) extensive washing steps for the autosampler and solid phase extraction (SPE) cartridge; and (3) a post-analysis cleaning step for the whole system. Under the above conditions, the resolution and sensitivity were significantly improved. Twelve target PFASs were baseline-separated (2.5-7.0min) within a 10-min of acquisition time. The limits of detection (LODs) were 0.01ng/mL or lower for all of the target compounds, making this method 5 times more sensitive than previously published methods. The newly developed method was validated in the linear range of 0.01-50ng/mL, and the accuracy (recovery between 80 and 120%) and precision (RSD<20%) were acceptable at three spiked levels (0.25, 2.5, and 25ng/mL). The method development and validation results demonstrated that this method was precise, accurate, and robust, with high-throughput (∼10min per

  9. An integrated strategy for rapid and accurate determination of free and cell-bound microcystins and related peptides in natural blooms by liquid chromatography-electrospray-high resolution mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry using both positive and negative ionization modes.

    Science.gov (United States)

    Flores, Cintia; Caixach, Josep

    2015-08-14

    An integrated high resolution mass spectrometry (HRMS) strategy has been developed for rapid and accurate determination of free and cell-bound microcystins (MCs) and related peptides in water blooms. The natural samples (water and algae) were filtered for independent analysis of aqueous and sestonic fractions. These fractions were analyzed by MALDI-TOF/TOF-MS and ESI-Orbitrap-HCD-MS. MALDI, ESI and the study of fragmentation sequences have been provided crucial structural information. The potential of combined positive and negative ionization modes, full scan and fragmentation acquisition modes (TOF/TOF and HCD) by HRMS and high resolution and accurate mass was investigated in order to allow unequivocal determination of MCs. Besides, a reliable quantitation has been possible by HRMS. This composition helped to decrease the probability of false positives and negatives, as alternative to commonly used LC-ESI-MS/MS methods. The analysis was non-target, therefore covered the possibility to analyze all MC analogs concurrently without any pre-selection of target MC. Furthermore, archived data was subjected to retrospective "post-targeted" analysis and a screening of other potential toxins and related peptides as anabaenopeptins in the samples was done. Finally, the MS protocol and identification tools suggested were applied to the analysis of characteristic water blooms from Spanish reservoirs.

  10. Accurate Method for Determining Adhesion of Cantilever Beams

    Energy Technology Data Exchange (ETDEWEB)

    Michalske, T.A.; de Boer, M.P.

    1999-01-08

    Using surface micromachined samples, we demonstrate the accurate measurement of cantilever beam adhesion by using test structures which are adhered over long attachment lengths. We show that this configuration has a deep energy well, such that a fracture equilibrium is easily reached. When compared to the commonly used method of determining the shortest attached beam, the present method is much less sensitive to variations in surface topography or to details of capillary drying.

  11. Towards an accurate determination of the age of the Universe

    CERN Document Server

    Jiménez, R

    1998-01-01

    In the past 40 years a considerable effort has been focused in determining the age of the Universe at zero redshift using several stellar clocks. In this review I will describe the best theoretical methods to determine the age of the oldest Galactic Globular Clusters (GC). I will also argue that a more accurate age determination may come from passively evolving high-redshift ellipticals. In particular, I will review two new methods to determine the age of GC. These two methods are more accurate than the classical isochrone fitting technique. The first method is based on the morphology of the horizontal branch and is independent of the distance modulus of the globular cluster. The second method uses a careful binning of the stellar luminosity function which determines simultaneously the distance and age of the GC. It is found that the oldest GCs have an age of $13.5 \\pm 2$ Gyr. The absolute minimum age for the oldest GCs is 10.5 Gyr and the maximum is 16.0 Gyr (with 99% confidence). Therefore, an Einstein-De S...

  12. Accurate mass replacement method for the sediment concentration measurement with a constant volume container

    Science.gov (United States)

    Ban, Yunyun; Chen, Tianqin; Yan, Jun; Lei, Tingwu

    2017-04-01

    The measurement of sediment concentration in water is of great importance in soil erosion research and soil and water loss monitoring systems. The traditional weighing method has long been the foundation of all the other measuring methods and instrument calibration. The development of a new method to replace the traditional oven-drying method is of interest in research and practice for the quick and efficient measurement of sediment concentration, especially field measurements. A new method is advanced in this study for accurately measuring the sediment concentration based on the accurate measurement of the mass of the sediment-water mixture in the confined constant volume container (CVC). A sediment-laden water sample is put into the CVC to determine its mass before the CVC is filled with water and weighed again for the total mass of the water and sediments in the container. The known volume of the CVC, the mass of sediment-laden water, and sediment particle density are used to calculate the mass of water, which is replaced by sediments, therefore sediment concentration of the sample is calculated. The influence of water temperature was corrected by measuring water density to determine the temperature of water before measurements were conducted. The CVC was used to eliminate the surface tension effect so as to obtain the accurate volume of water and sediment mixture. Experimental results showed that the method was capable of measuring the sediment concentration from 0.5 up to 1200 kg m‑3. A good liner relationship existed between the designed and measured sediment concentrations with all the coefficients of determination greater than 0.999 and the averaged relative error less than 0.2%. All of these seem to indicate that the new method is capable of measuring a full range of sediment concentration above 0.5 kg m‑3 to replace the traditional oven-drying method as a standard method for evaluating and calibrating other methods.

  13. On uplimit of accurate measurement of tau mass

    CERN Document Server

    Mo, X H

    2016-01-01

    Tau lepton as one of three elementary leptons in nature, the measurement of its mass has ever been performed since its discovery. The present relative accuracy is already at the level of better than 10 to minus 4 and more effects are still made in order to increase the accuracy further. However, the analysis of available techniques for and expectable luminosity from e+e- collider indicates that the precision uplimit of tau mass is almost reached, which means that brand new approaches should be looked for if the great improvement is yearned for.

  14. An accurate mass and radius measurement for an ultracool white dwarf

    CERN Document Server

    Parsons, S G; Marsh, T R; Bergeron, P; Copperwheat, C M; Dhillon, V S; Bento, J; Littlefair, S P; Schreiber, M R

    2012-01-01

    Studies of cool white dwarfs in the solar neighbourhood have placed a limit on the age of the Galactic disk of 8-9 billion years. However, determining their cooling ages requires the knowledge of their effective temperatures, masses, radii, and atmospheric composition. So far, these parameters could only be inferred for a small number of ultracool white dwarfs for which an accurate distance is known, by fitting their spectral energy distributions (SEDs) in conjunction with a theoretical mass-radius relation. However, the mass-radius relation remains largely untested, and the derived cooling ages are hence model-dependent. Here we report direct measurements of the mass and radius of an ultracool white dwarf in the double-lined eclipsing binary SDSS J013851.54-001621.6. We find M(WD)=0.529+/-0.010Msol and R(WD)=0.0131+/-0.0003Rsol. Our measurements are consistent with the mass-radius relation and we determine a robust cooling age of 9.5 billion years for the 3570K white dwarf. We find that the mass and radius o...

  15. Quantitative proteomics using the high resolution accurate mass capabilities of the quadrupole-orbitrap mass spectrometer.

    Science.gov (United States)

    Gallien, Sebastien; Domon, Bruno

    2014-08-01

    High resolution/accurate mass hybrid mass spectrometers have considerably advanced shotgun proteomics and the recent introduction of fast sequencing capabilities has expanded its use for targeted approaches. More specifically, the quadrupole-orbitrap instrument has a unique configuration and its new features enable a wide range of experiments. An overview of the analytical capabilities of this instrument is presented, with a focus on its application to quantitative analyses. The high resolution, the trapping capability and the versatility of the instrument have allowed quantitative proteomic workflows to be redefined and new data acquisition schemes to be developed. The initial proteomic applications have shown an improvement of the analytical performance. However, as quantification relies on ion trapping, instead of ion beam, further refinement of the technique can be expected.

  16. An accurate determination of the Avogadro constant by counting the atoms in a 28Si crystal

    CERN Document Server

    Andreas, B; Bartl, G; Becker, P; Bettin, H; Borys, M; Busch, I; Gray, M; Fuchs, P; Fujii, K; Fujimoto, H; Kessler, E; Krumrey, M; Kuetgens, U; Kuramoto, N; Mana, G; Manson, P; Massa, E; Mizushima, S; Nicolaus, A; Picard, A; Pramann, A; Rienitz, O; Schiel, D; Valkiers, S; Waseda, A

    2010-01-01

    The Avogadro constant links the atomic and the macroscopic properties of matter. Since the molar Planck constant is well known via the measurement of the Rydberg constant, it is also closely related to the Planck constant. In addition, its accurate determination is of paramount importance for a definition of the kilogram in terms of a fundamental constant. We describe a new approach for its determination by "counting" the atoms in 1 kg single-crystal spheres, which are highly enriched with the 28Si isotope. It enabled isotope dilution mass spectroscopy to determine the molar mass of the silicon crystal with unprecedented accuracy. The value obtained, 6.02214084(18) x 10^23 mol^-1, is the most accurate input datum for a new definition of the kilogram.

  17. Accurate correction of magnetic field instabilities for high-resolution isochronous mass measurements in storage rings

    CERN Document Server

    Shuai, P; Zhang, Y H; Litvinov, Yu A; Wang, M; Tu, X L; Blaum, K; Zhou, X H; Yuan, Y J; Audi, G; Yan, X L; Chen, X C; Xu, X; Zhang, W; Sun, B H; Yamaguchi, T; Chen, R J; Fu, C Y; Ge, Z; Huang, W J; Liu, D W; Xing, Y M; Zeng, Q

    2014-01-01

    Isochronous mass spectrometry (IMS) in storage rings is a successful technique for accurate mass measurements of short-lived nuclides with relative precision of about $10^{-5}-10^{-7}$. Instabilities of the magnetic fields in storage rings are one of the major contributions limiting the achievable mass resolving power, which is directly related to the precision of the obtained mass values. A new data analysis method is proposed allowing one to minimise the effect of such instabilities. The masses of the previously measured at the CSRe $^{41}$Ti, $^{43}$V, $^{47}$Mn, $^{49}$Fe, $^{53}$Ni and $^{55}$Cu nuclides were re-determined with this method. An improvement of the mass precision by a factor of $\\sim 1.7$ has been achieved for $^{41}$Ti and $^{43}$V. The method can be applied to any isochronous mass experiment irrespective of the accelerator facility. Furthermore, the method can be used as an on-line tool for checking the isochronous conditions of the storage ring.

  18. Accurate determination of segmented X-ray detector geometry.

    Science.gov (United States)

    Yefanov, Oleksandr; Mariani, Valerio; Gati, Cornelius; White, Thomas A; Chapman, Henry N; Barty, Anton

    2015-11-02

    Recent advances in X-ray detector technology have resulted in the introduction of segmented detectors composed of many small detector modules tiled together to cover a large detection area. Due to mechanical tolerances and the desire to be able to change the module layout to suit the needs of different experiments, the pixels on each module might not align perfectly on a regular grid. Several detectors are designed to permit detector sub-regions (or modules) to be moved relative to each other for different experiments. Accurate determination of the location of detector elements relative to the beam-sample interaction point is critical for many types of experiment, including X-ray crystallography, coherent diffractive imaging (CDI), small angle X-ray scattering (SAXS) and spectroscopy. For detectors with moveable modules, the relative positions of pixels are no longer fixed, necessitating the development of a simple procedure to calibrate detector geometry after reconfiguration. We describe a simple and robust method for determining the geometry of segmented X-ray detectors using measurements obtained by serial crystallography. By comparing the location of observed Bragg peaks to the spot locations predicted from the crystal indexing procedure, the position, rotation and distance of each module relative to the interaction region can be refined. We show that the refined detector geometry greatly improves the results of experiments.

  19. Accurate, reliable control of process gases by mass flow controllers

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, J.; McKnight, T.

    1997-02-01

    The thermal mass flow controller, or MFC, has become an instrument of choice for the monitoring and controlling of process gas flow throughout the materials processing industry. These MFCs are used on CVD processes, etching tools, and furnaces and, within the semiconductor industry, are used on 70% of the processing tools. Reliability and accuracy are major concerns for the users of the MFCs. Calibration and characterization technologies for the development and implementation of mass flow devices are described. A test facility is available to industry and universities to test and develop gas floe sensors and controllers and evaluate their performance related to environmental effects, reliability, reproducibility, and accuracy. Additional work has been conducted in the area of accuracy. A gravimetric calibrator was invented that allows flow sensors to be calibrated in corrosive, reactive gases to an accuracy of 0.3% of reading, at least an order of magnitude better than previously possible. Although MFCs are typically specified with accuracies of 1% of full scale, MFCs may often be implemented with unwarranted confidence due to the conventional use of surrogate gas factors. Surrogate gas factors are corrections applied to process flow indications when an MFC has been calibrated on a laboratory-safe surrogate gas, but is actually used on a toxic, or corrosive process gas. Previous studies have indicated that the use of these factors may cause process flow errors of typically 10%, but possibly as great as 40% of full scale. This paper will present possible sources of error in MFC process gas flow monitoring and control, and will present an overview of corrective measures which may be implemented with MFC use to significantly reduce these sources of error.

  20. Alignment of capillary electrophoresis-mass spectrometry datasets using accurate mass information.

    Science.gov (United States)

    Nevedomskaya, Ekaterina; Derks, Rico; Deelder, André M; Mayboroda, Oleg A; Palmblad, Magnus

    2009-12-01

    Capillary electrophoresis-mass spectrometry (CE-MS) is a powerful technique for the analysis of small soluble compounds in biological fluids. A major drawback of CE is the poor migration time reproducibility, which makes it difficult to combine data from different experiments and correctly assign compounds. A number of alignment algorithms have been developed but not all of them can cope with large and irregular time shifts between CE-MS runs. Here we present a genetic algorithm designed for alignment of CE-MS data using accurate mass information. The utility of the algorithm was demonstrated on real data, and the results were compared with one of the existing packages. The new algorithm showed a significant reduction of elution time variation in the aligned datasets. The importance of mass accuracy for the performance of the algorithm was also demonstrated by comparing alignments of datasets from a standard time-of-flight (TOF) instrument with those from the new ultrahigh resolution TOF maXis (Bruker Daltonics).

  1. Cephalometric analysis for accurately determining the vertical dimension (case report

    Directory of Open Access Journals (Sweden)

    Wahipa Wiro

    2017-04-01

    Full Text Available Objective : Determination of the vertical dimension of occlusion (DVO tends to changes throughout the human life. The vertical dimension is determined by the interocclusal point of the upper and lower teeth contact so the application is limited when the natural teeth was missing. As the result, many functional and aesthetic changes are occurred in the whole orofacial region and stomatognathic system. DVO is one of the difficult stages in prosthodontic treatment. Most of the techniques to determine DVO in edentulous patients are based on the soft tissue references, which can cause the different measurements. Cephalometric analysis allows the evaluation of bone growth changes and can be used as a diagnostic tool in prosthodontics to evaluate the results of prosthodontic rehabilitation. Methods : The purpose of this case report was to find out the results of the vertical dimension of occlusion measurements in maxillomandibular relation by using cephalometric photo in patients who have been long lost their teeth and have never been using denture. Results : A 50 year old female patient, partially edentulous on the upper and lower jaw with the remaining teeth were 12 (residual root, 11,21,23,33 and 43. The remaining teeth were endodontically treated prior the complete denture procedure. Cephalometric photo was done in patients after making bite rim, upper and lower bite rim were given metal marker, the image was traced, then measured between metal to get the vertical dimension of occlusion. Conclusion : The measurement results of the vertical dimension of occlusion by using cephalometric photo on making full denture were more accurate, so it could improve and restore the masticatory function, aesthetic function and phonetics.

  2. The Megamaser Cosmology Project. III. Accurate Masses of Seven Supermassive Black Holes in Active Galaxies with Circumnuclear Megamaser Disks

    Science.gov (United States)

    Kuo, C. Y.; Braatz, J. A.; Condon, J. J.; Impellizzeri, C. M. V.; Lo, K. Y.; Zaw, I.; Schenker, M.; Henkel, C.; Reid, M. J.; Greene, J. E.

    2011-01-01

    Observations of H2O masers from circumnuclear disks in active galaxies for the Megamaser Cosmology Project (MCP) allow accurate measurement of the mass of supermassive black holes (BH) in these galaxies. We present the Very Long Baseline Interferometry images and kinematics of water maser emission in six active galaxies: NGC 1194, NGC 2273, NGC 2960 (Mrk 1419), NGC 4388, NGC 6264 and NGC 6323. We use the Keplerian rotation curves of these six megamaser galaxies, plus a seventh previously published, to determine accurate enclosed masses within the central ~0.3 pc of these galaxies, smaller than the radius of the sphere of influence of the central mass in all cases. We also set lower limits to the central mass densities of between 0.12 × 1010 and 61 × 1010 M sun pc-3. For six of the seven disks, the high central densities rule out clusters of stars or stellar remnants as the central objects, and this result further supports our assumption that the enclosed mass can be attributed predominantly to a supermassive BH. The seven BHs have masses ranging between 0.75 × 107 and 6.5 × 107 M sun, with the mass errors dominated by the uncertainty of the Hubble constant. We compare the megamaser BH mass determination with BH mass measured from the virial estimation method. The virial estimation BH mass in four galaxies is consistent with the megamaser BH mass, but the virial mass uncertainty is much greater. Circumnuclear megamaser disks allow the best mass determination of the central BH mass in external galaxies and significantly improve the observational basis at the low-mass end of the M-σsstarf relation. The M-σsstarf relation may not be a single, low-scatter power law as originally proposed. MCP observations continue and we expect to obtain more maser BH masses in the future.

  3. How accurately can the deuterium abundance be determined?

    CERN Document Server

    Levshakov, S A; Takahara, F

    1997-01-01

    By using a Reverse Monte Carlo technique aimed at the inverse problem in the analysis of the H+D Ly-a absorption from QSO spectra we have estimated the physical parameters of the gas and the large-scale line of sight velocity structure towards Q1009+2956 at z = 2.504 (observations by Burles and Tytler, astro-ph/9603070). We show that for a precise evaluation of the column densities, the detailed velocity field structure is to be determined simultaneously. Our study of the z = 2.504 system yields D/H = (3.75 +/- 0.85)*10^{-5} (2sigma) which gives good agreement between the standard BBN predictions and observational constraints on extra-galactic 4He mass fraction and 7Li abundances in the atmospheres of population II (halo) starts. We conclude that the discordance of D/H with the light element abundances discussed in the literature is a consequence of the assumption of microturbulence (i.e. completely uncorrelated bulk motions) in the analysis of line profiles. The generalized model accounting for a finite corr...

  4. Identification of "Known Unknowns" Utilizing Accurate Mass Data and ChemSpider

    Science.gov (United States)

    Little, James L.; Williams, Antony J.; Pshenichnov, Alexey; Tkachenko, Valery

    2012-01-01

    In many cases, an unknown to an investigator is actually known in the chemical literature, a reference database, or an internet resource. We refer to these types of compounds as "known unknowns." ChemSpider is a very valuable internet database of known compounds useful in the identification of these types of compounds in commercial, environmental, forensic, and natural product samples. The database contains over 26 million entries from hundreds of data sources and is provided as a free resource to the community. Accurate mass mass spectrometry data is used to query the database by either elemental composition or a monoisotopic mass. Searching by elemental composition is the preferred approach. However, it is often difficult to determine a unique elemental composition for compounds with molecular weights greater than 600 Da. In these cases, searching by the monoisotopic mass is advantageous. In either case, the search results are refined by sorting the number of references associated with each compound in descending order. This raises the most useful candidates to the top of the list for further evaluation. These approaches were shown to be successful in identifying "known unknowns" noted in our laboratory and for compounds of interest to others.

  5. Mass transport and direction dependent battery modeling for accurate on-line power capability prediction

    Energy Technology Data Exchange (ETDEWEB)

    Wiegman, H.L.N. [General Electric Corporate Research and Development, Schenectady, NY (United States)

    2000-07-01

    Some recent advances in battery modeling were discussed with reference to on-line impedance estimates and power performance predictions for aqueous solution, porous electrode cell structures. The objective was to determine which methods accurately estimate a battery's internal state and power capability while operating a charge and sustaining a hybrid electric vehicle (HEV) over a wide range of driving conditions. The enhancements to the Randles-Ershler equivalent electrical model of common cells with lead-acid, nickel-cadmium and nickel-metal hydride chemistries were described. This study also investigated which impedances are sensitive to boundary layer charge concentrations and mass transport limitations. Non-linear impedances were shown to significantly affect the battery's ability to process power. The main advantage of on-line estimating a battery's impedance state and power capability is that the battery can be optimally sized for any application. refs., tabs., figs., append.

  6. Fast and accurate determination of modularity and its effect size

    CERN Document Server

    Treviño, Santiago; Del Genio, Charo I; Bassler, Kevin E

    2014-01-01

    We present a fast spectral algorithm for community detection in complex networks. Our method searches for the partition with the maximum value of the modularity via the interplay of several refinement steps that include both agglomeration and division. We validate the accuracy of the algorithm by applying it to several real-world benchmark networks. On all these, our algorithm performs as well or better than any other known polynomial scheme. This allows us to extensively study the modularity distribution in ensembles of Erd\\H{o}s-R\\'enyi networks, producing theoretical predictions for means and variances inclusive of finite-size corrections. Our work provides a way to accurately estimate the effect size of modularity, providing a $z$-score measure of it and enabling a more informative comparison of networks with different numbers of nodes and links.

  7. In-Depth Glycoproteomic Characterization of γ-Conglutin by High-Resolution Accurate Mass Spectrometry

    Science.gov (United States)

    Schiarea, Silvia; Arnoldi, Lolita; Fanelli, Roberto; De Combarieu, Eric; Chiabrando, Chiara

    2013-01-01

    The molecular characterization of bioactive food components is necessary for understanding the mechanisms of their beneficial or detrimental effects on human health. This study focused on γ-conglutin, a well-known lupin seed N-glycoprotein with health-promoting properties and controversial allergenic potential. Given the importance of N-glycosylation for the functional and structural characteristics of proteins, we studied the purified protein by a mass spectrometry-based glycoproteomic approach able to identify the structure, micro-heterogeneity and attachment site of the bound N-glycan(s), and to provide extensive coverage of the protein sequence. The peptide/N-glycopeptide mixtures generated by enzymatic digestion (with or without N-deglycosylation) were analyzed by high-resolution accurate mass liquid chromatography–multi-stage mass spectrometry. The four main micro-heterogeneous variants of the single N-glycan bound to γ-conglutin were identified as Man2(Xyl) (Fuc) GlcNAc2, Man3(Xyl) (Fuc) GlcNAc2, GlcNAcMan3(Xyl) (Fuc) GlcNAc2 and GlcNAc 2Man3(Xyl) (Fuc) GlcNAc2. These carry both core β1,2-xylose and core α1-3-fucose (well known Cross-Reactive Carbohydrate Determinants), but corresponding fucose-free variants were also identified as minor components. The N-glycan was proven to reside on Asn131, one of the two potential N-glycosylation sites. The extensive coverage of the γ-conglutin amino acid sequence suggested three alternative N-termini of the small subunit, that were later confirmed by direct-infusion Orbitrap mass spectrometry analysis of the intact subunit. PMID:24069245

  8. In-depth glycoproteomic characterization of γ-conglutin by high-resolution accurate mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Silvia Schiarea

    Full Text Available The molecular characterization of bioactive food components is necessary for understanding the mechanisms of their beneficial or detrimental effects on human health. This study focused on γ-conglutin, a well-known lupin seed N-glycoprotein with health-promoting properties and controversial allergenic potential. Given the importance of N-glycosylation for the functional and structural characteristics of proteins, we studied the purified protein by a mass spectrometry-based glycoproteomic approach able to identify the structure, micro-heterogeneity and attachment site of the bound N-glycan(s, and to provide extensive coverage of the protein sequence. The peptide/N-glycopeptide mixtures generated by enzymatic digestion (with or without N-deglycosylation were analyzed by high-resolution accurate mass liquid chromatography-multi-stage mass spectrometry. The four main micro-heterogeneous variants of the single N-glycan bound to γ-conglutin were identified as Man2(Xyl (Fuc GlcNAc2, Man3(Xyl (Fuc GlcNAc2, GlcNAcMan3(Xyl (Fuc GlcNAc2 and GlcNAc 2Man3(Xyl (Fuc GlcNAc2. These carry both core β1,2-xylose and core α1-3-fucose (well known Cross-Reactive Carbohydrate Determinants, but corresponding fucose-free variants were also identified as minor components. The N-glycan was proven to reside on Asn131, one of the two potential N-glycosylation sites. The extensive coverage of the γ-conglutin amino acid sequence suggested three alternative N-termini of the small subunit, that were later confirmed by direct-infusion Orbitrap mass spectrometry analysis of the intact subunit.

  9. Main-Sequence Effective Temperatures from a Revised Mass-Luminosity Relation Based on Accurate Properties

    CERN Document Server

    Eker, Z; Soydugan, E; Bilir, S; Gokce, E Yaz; Steer, I; Tuysuz, M; Senyuz, T; Demircan, O

    2015-01-01

    The mass-luminosity (M-L), mass-radius (M-R) and mass-effective temperature ($M-T_{eff}$) diagrams for a subset of galactic nearby main-sequence stars with masses and radii accurate to $\\leq 3\\%$ and luminosities accurate to $\\leq 30\\%$ (268 stars) has led to a putative discovery. Four distinct mass domains have been identified, which we have tentatively associated with low, intermediate, high, and very high mass main-sequence stars, but which nevertheless are clearly separated by three distinct break points at 1.05, 2.4, and 7$M_{\\odot}$ within the mass range studied of $0.38-32M_{\\odot}$. Further, a revised mass-luminosity relation (MLR) is found based on linear fits for each of the mass domains identified. The revised, mass-domain based MLRs, which are classical ($L \\propto M^{\\alpha}$), are shown to be preferable to a single linear, quadratic or cubic equation representing as an alternative MLR. Stellar radius evolution within the main-sequence for stars with $M>1M_{\\odot}$ is clearly evident on the M-R d...

  10. Light Quark Mass Effects in Bottom Quark Mass Determinations

    OpenAIRE

    Hoang, A. H.

    2001-01-01

    Recent results for charm quark mass effects in perturbative bottom quark mass determinations from $\\Upsilon$ mesons are reviewed. The connection between the behavior of light quark mass corrections and the infrared sensitivity of some bottom quark mass definitions is examined in some detail.

  11. Galaxy And Mass Assembly: accurate panchromatic photometry from optical priors using LAMBDAR

    Science.gov (United States)

    Wright, A. H.; Robotham, A. S. G.; Bourne, N.; Driver, S. P.; Dunne, L.; Maddox, S. J.; Alpaslan, M.; Andrews, S. K.; Bauer, A. E.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Clarke, C.; Cluver, M.; Davies, L. J. M.; Grootes, M. W.; Holwerda, B. W.; Hopkins, A. M.; Jarrett, T. H.; Kafle, P. R.; Lange, R.; Liske, J.; Loveday, J.; Moffett, A. J.; Norberg, P.; Popescu, C. C.; Smith, M.; Taylor, E. N.; Tuffs, R. J.; Wang, L.; Wilkins, S. M.

    2016-07-01

    We present the Lambda Adaptive Multi-Band Deblending Algorithm in R (LAMBDAR), a novel code for calculating matched aperture photometry across images that are neither pixel- nor PSF-matched, using prior aperture definitions derived from high-resolution optical imaging. The development of this program is motivated by the desire for consistent photometry and uncertainties across large ranges of photometric imaging, for use in calculating spectral energy distributions. We describe the program, specifically key features required for robust determination of panchromatic photometry: propagation of apertures to images with arbitrary resolution, local background estimation, aperture normalization, uncertainty determination and propagation, and object deblending. Using simulated images, we demonstrate that the program is able to recover accurate photometric measurements in both high-resolution, low-confusion, and low-resolution, high-confusion, regimes. We apply the program to the 21-band photometric data set from the Galaxy And Mass Assembly (GAMA) Panchromatic Data Release (PDR; Driver et al. 2016), which contains imaging spanning the far-UV to the far-IR. We compare photometry derived from LAMBDAR with that presented in Driver et al. (2016), finding broad agreement between the data sets. None the less, we demonstrate that the photometry from LAMBDAR is superior to that from the GAMA PDR, as determined by a reduction in the outlier rate and intrinsic scatter of colours in the LAMBDAR data set. We similarly find a decrease in the outlier rate of stellar masses and star formation rates using LAMBDAR photometry. Finally, we note an exceptional increase in the number of UV and mid-IR sources able to be constrained, which is accompanied by a significant increase in the mid-IR colour-colour parameter-space able to be explored.

  12. Evaluation of accurate mass and relative isotopic abundance measurements in the LTQ-orbitrap mass spectrometer for further metabolomics database building.

    Science.gov (United States)

    Xu, Ying; Heilier, Jean-François; Madalinski, Geoffrey; Genin, Eric; Ezan, Eric; Tabet, Jean-Claude; Junot, Christophe

    2010-07-01

    Recently, high-resolution mass spectrometry has been largely employed for compound identification, thanks to accurate mass measurements. As additional information, relative isotope abundance (RIA) is often needed to reduce the number of candidates prior to tandem MS(n). Here, we report on the evaluation of the LTQ-Orbitrap, in terms of accurate mass and RIA measurements for building further metabolomics spectral databases. Accurate mass measurements were achieved in the ppm range, using external calibration within 24 h, and remained at evaluated in different data sets. First of all, 137 solutions of commercial compounds were analyzed by flow injection analysis in both the positive and negative ion modes. It was found that the ion abundance was the main factor impacting the accuracy of RIA measurements. It was possible to define some intensity thresholds above which errors were systematically transmission between the LTQ ion trap and the Orbitrap analyzer on RIA measurement errors was found, whereas the reliability of RIA measurements was dramatically improved by reducing the mass detection window. It was also observed that the signal integration method had a significant impact on RIA measurement errors, with the most-reliable results being obtained with peak height integrations. Finally, automatic integrations using the data preprocessing software XCMS and MZmine gave results similar to those obtained by manual integration, suggesting that it is relevant to use the RIA information in automatic elemental composition determination software from metabolomic peak tables.

  13. The Megamaser Cosmology Project. III. Accurate Masses of Seven Supermassive Black Holes in Active Galaxies with Circumnuclear Megamaser Disks

    CERN Document Server

    Kuo, C Y; Condon, J J; Impellizzeri, C M V; Lo, K Y; Zaw, I; Schenker, M; Henkel, C; Reid, M J; Greene, J E

    2010-01-01

    Observations of H$_2$O masers from circumnuclear disks in active galaxies for the Megamaser Cosmology Project allow accurate measurement of the mass of supermassive black holes (BH) in these galaxies. We present the Very Long Baseline Interferometry (VLBI) images and kinematics of water maser emission in six active galaxies: NGC~1194, NGC~2273, NGC~2960 (Mrk~1419), NGC~4388, NGC~6264 and NGC~6323. We use the Keplerian rotation curves of these six megamaser galaxies, plus a seventh previously published, to determine accurate enclosed masses within the central $\\sim0.3$ pc of these galaxies, smaller than the radius of the sphere of influence of the central mass in all cases. We also set lower limits to the central mass densities of between 0.12 and 60 $\\times 10^{10} M_{\\odot}$~pc$^{-3}$. For six of the seven disks, the high central densities rule out clusters of stars or stellar remnants as the central objects, and this result further supports our assumption that the enclosed mass can be attributed predominant...

  14. Accurate Quantitation of Dystrophin Protein in Human Skeletal Muscle Using Mass Spectrometry

    OpenAIRE

    Brown, Kristy J; Marathi, Ramya; Fiorillo, Alyson A; Ciccimaro, Eugene F.; Sharma, Seema; Rowlands, David S.; Rayavarapu, Sree; Nagaraju, Kanneboyina; Eric P. Hoffman; Hathout, Yetrib

    2012-01-01

    Quantitation of human dystrophin protein in muscle biopsies is a clinically relevant endpoint for both diagnosis and response to dystrophin-replacement therapies for dystrophinopathies. A robust and accurate assay would enable the use of dystrophin as a surrogate biomarker, particularly in exploratory Phase 2 trials. Currently available methods to quantitate dystrophin rely on immunoblot or immunohistochemistry methods that are not considered robust. Here we present a mass spectrometry based ...

  15. Accurate Prediction of the Ammonia Probes of a Variable Proton-to-Electron Mass Ratio

    CERN Document Server

    Owens, Alec; Thiel, Walter; Špirko, Vladimir

    2015-01-01

    A comprehensive study of the mass sensitivity of the vibration-rotation-inversion transitions of $^{14}$NH$_3$, $^{15}$NH$_3$, $^{14}$ND$_3$, and $^{15}$ND$_3$ is carried out variationally using the TROVE approach. Variational calculations are robust and accurate, offering a new way to compute sensitivity coefficients. Particular attention is paid to the $\\Delta k=\\pm 3$ transitions between the accidentally coinciding rotation-inversion energy levels of the $\

  16. Fast and accurate mock catalogue generation for low-mass galaxies

    Science.gov (United States)

    Koda, Jun; Blake, Chris; Beutler, Florian; Kazin, Eyal; Marin, Felipe

    2016-06-01

    We present an accurate and fast framework for generating mock catalogues including low-mass haloes, based on an implementation of the COmoving Lagrangian Acceleration (COLA) technique. Multiple realisations of mock catalogues are crucial for analyses of large-scale structure, but conventional N-body simulations are too computationally expensive for the production of thousands of realizations. We show that COLA simulations can produce accurate mock catalogues with a moderate computation resource for low- to intermediate-mass galaxies in 1012 M⊙ haloes, both in real and redshift space. COLA simulations have accurate peculiar velocities, without systematic errors in the velocity power spectra for k ≤ 0.15 h Mpc-1, and with only 3-per cent error for k ≤ 0.2 h Mpc-1. We use COLA with 10 time steps and a Halo Occupation Distribution to produce 600 mock galaxy catalogues of the WiggleZ Dark Energy Survey. Our parallelized code for efficient generation of accurate halo catalogues is publicly available at github.com/junkoda/cola_halo.

  17. High-accuracy mass determination of unstable nuclei with a Penning trap mass spectrometer

    CERN Multimedia

    2002-01-01

    The mass of a nucleus is its most fundamental property. A systematic study of nuclear masses as a function of neutron and proton number allows the observation of collective and single-particle effects in nuclear structure. Accurate mass data are the most basic test of nuclear models and are essential for their improvement. This is especially important for the astrophysical study of nuclear synthesis. In order to achieve the required high accuracy, the mass of ions captured in a Penning trap is determined via their cyclotron frequency $ \

  18. Directed sample interrogation utilizing an accurate mass exclusion-based data-dependent acquisition strategy (AMEx).

    Science.gov (United States)

    Rudomin, Emily L; Carr, Steven A; Jaffe, Jacob D

    2009-06-01

    The ability to perform thorough sampling is of critical importance when using mass spectrometry to characterize complex proteomic mixtures. A common approach is to reinterrogate a sample multiple times by LC-MS/MS. However, the conventional data-dependent acquisition methods that are typically used in proteomics studies will often redundantly sample high-intensity precursor ions while failing to sample low-intensity precursors entirely. We describe a method wherein the masses of successfully identified peptides are used to generate an accurate mass exclusion list such that those precursors are not selected for sequencing during subsequent analyses. We performed multiple concatenated analytical runs to sample a complex cell lysate, using either accurate mass exclusion-based data-dependent acquisition (AMEx) or standard data-dependent acquisition, and found that utilization of AMEx on an ESI-Orbitrap instrument significantly increases the total number of validated peptide identifications relative to a standard DDA approach. The additional identified peptides represent precursor ions that exhibit low signal intensity in the sample. Increasing the total number of peptide identifications augmented the number of proteins identified, as well as improved the sequence coverage of those proteins. Together, these data indicate that using AMEx is an effective strategy to improve the characterization of complex proteomic mixtures.

  19. Mass Determination of New Particle States

    CERN Document Server

    Serna, Mario

    2008-01-01

    We study theoretical and experimental facets of mass determination of new particle states. Assuming supersymmetry, we update the quark and lepton mass matrices at the grand unification scale accounting for threshold corrections enhanced by large tan beta. From the hypothesis that quark and lepton masses satisfy a classic set of relationships suggested in some Grand Unified Theories (GUTs), we predict tan beta needs to be large, and the gluino's soft mass needs to have the opposite sign to the wino's soft mass. Existing tools to measure the phase of the gluino's mass at upcoming hadron colliders require model-independent, kinematic techniques to determine the masses of the new supersymmetric particle states. We discuss the current techniques to determine the mass of invisible particles. We review the transverse mass kinematic variable M_{T2} and the use of invariant-mass edges to find relationships between masses. Next, we introduce a new technique to add additional constraints between the masses of new partic...

  20. Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes

    Science.gov (United States)

    Stassun, Keivan G.; Collins, Karen A.; Gaudi, B. Scott

    2017-03-01

    We present empirical measurements of the radii of 116 stars that host transiting planets. These radii are determined using only direct observables—the bolometric flux at Earth, the effective temperature, and the parallax provided by the Gaia first data release—and thus are virtually model independent, with extinction being the only free parameter. We also determine each star’s mass using our newly determined radius and the stellar density, a virtually model independent quantity itself from previously published transit analyses. These stellar radii and masses are in turn used to redetermine the transiting-planet radii and masses, again using only direct observables. The median uncertainties on the stellar radii and masses are 8% and 30%, respectively, and the resulting uncertainties on the planet radii and masses are 9% and 22%, respectively. These accuracies are generally larger than previously published model-dependent precisions of 5% and 6% on the planet radii and masses, respectively, but the newly determined values are purely empirical. We additionally report radii for 242 stars hosting radial-velocity (non-transiting) planets, with a median achieved accuracy of ≈2%. Using our empirical stellar masses we verify that the majority of putative “retired A stars” in the sample are indeed more massive than ∼1.2 {M}ȯ . Most importantly, the bolometric fluxes and angular radii reported here for a total of 498 planet host stars—with median accuracies of 1.7% and 1.8%, respectively—serve as a fundamental data set to permit the re-determination of transiting-planet radii and masses with the Gaia second data release to ≈3% and ≈5% accuracy, better than currently published precisions, and determined in an entirely empirical fashion.

  1. Accurate-mass databases for comprehensive screening of pesticide residues in food by fast liquid chromatography time-of-flight mass spectrometry.

    Science.gov (United States)

    Mezcua, Milagros; Malato, Octavio; García-Reyes, Juan F; Molina-Díaz, Antonio; Fernández-Alba, Amadeo R

    2009-02-01

    Because of the international trade of fruits and vegetables and the lack of harmonized regulations on the use of pesticides worldwide, the development of comprehensive screening methods for analyzing hundreds of pesticides and other banned chemicals is very convenient. This work reports the development and evaluation of a rapid automated screening method for determining pesticide residues in food using liquid chromatography electrospray time-of-flight mass spectrometry (LC-TOFMS) based on the use of an accurate-mass database. The database created includes data not only on the accurate masses of the target ions but also the characteristic in-source fragment ions (over 400 fragments included) and retention time data. This customized database was associated to commercially available software which extracted all the potential compounds of interest from the LC-TOFMS raw data of each sample and matched them against the database to search for targeted compounds in the sample. This automatic screening method requires a careful optimization of the accurate-mass window and retention time tolerances, which play a determinant role on the selectivity, accuracy, and throughput of the whole procedure. Values of 10 mDa for preliminary screening and 1 mDa/5 ppm for confirmation along with a +/-0.15 min retention time window were found to be optimum for the compounds and samples tested. The optimized methods enable the automated screening of ca. 300 compounds in less than 20 min including the LC-MS run and data processing. The proposed method was applied to 60 real samples, and the results of the positive findings compared well with those obtained using a liquid chromatography tandem mass spectrometry (LC-MS/MS) method (triple quadrupole). The rates obtained on the identification of compounds in spiked and real samples in an automated fashion at different concentration levels were over 95% of the compounds, thus revealing as a convenient tool for the large-scale screening of

  2. A statistical method for assessing peptide identification confidence in accurate mass and time tag proteomics.

    Science.gov (United States)

    Stanley, Jeffrey R; Adkins, Joshua N; Slysz, Gordon W; Monroe, Matthew E; Purvine, Samuel O; Karpievitch, Yuliya V; Anderson, Gordon A; Smith, Richard D; Dabney, Alan R

    2011-08-15

    Current algorithms for quantifying peptide identification confidence in the accurate mass and time (AMT) tag approach assume that the AMT tags themselves have been correctly identified. However, there is uncertainty in the identification of AMT tags, because this is based on matching LC-MS/MS fragmentation spectra to peptide sequences. In this paper, we incorporate confidence measures for the AMT tag identifications into the calculation of probabilities for correct matches to an AMT tag database, resulting in a more accurate overall measure of identification confidence for the AMT tag approach. The method is referenced as Statistical Tools for AMT Tag Confidence (STAC). STAC additionally provides a uniqueness probability (UP) to help distinguish between multiple matches to an AMT tag and a method to calculate an overall false discovery rate (FDR). STAC is freely available for download, as both a command line and a Windows graphical application.

  3. Accurate and Precise Determination of Uranium by Means of Extraction Spectrophotometric

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Uranium is an important nuclear material. Accurate determination of uranium is significant in the nuclear fuel production, accountancy, nuclear safeguards and other procedures of nuclear fuel cycle.

  4. SPARC: Mass Models for 175 Disk Galaxies with Spitzer Photometry and Accurate Rotation Curves

    CERN Document Server

    Lelli, Federico; Schombert, James M

    2016-01-01

    We introduce SPARC (Spitzer Photometry & Accurate Rotation Curves): a sample of 175 nearby galaxies with new surface photometry at 3.6 um and high-quality rotation curves from previous HI/Halpha studies. SPARC spans a broad range of morphologies (S0 to Irr), luminosities (~5 dex), and surface brightnesses (~4 dex). We derive [3.6] surface photometry and study structural relations of stellar and gas disks. We find that both the stellar mass-HI mass relation and the stellar radius-HI radius relation have significant intrinsic scatter, while the HI mass-radius relation is extremely tight. We build detailed mass models and quantify the ratio of baryonic-to-observed velocity (Vbar/Vobs) for different characteristic radii and values of the stellar mass-to-light ratio (M/L) at [3.6]. Assuming M/L=0.5 Msun/Lsun (as suggested by stellar population models) we find that (i) the gas fraction linearly correlates with total luminosity, (ii) the transition from star-dominated to gas-dominated galaxies roughly correspond...

  5. A simple and accurate model for Love wave based sensors: Dispersion equation and mass sensitivity

    Directory of Open Access Journals (Sweden)

    Jiansheng Liu

    2014-07-01

    Full Text Available Dispersion equation is an important tool for analyzing propagation properties of acoustic waves in layered structures. For Love wave (LW sensors, the dispersion equation with an isotropic-considered substrate is too rough to get accurate solutions; the full dispersion equation with a piezoelectric-considered substrate is too complicated to get simple and practical expressions for optimizing LW-based sensors. In this work, a dispersion equation is introduced for Love waves in a layered structure with an anisotropic-considered substrate and an isotropic guiding layer; an intuitive expression for mass sensitivity is also derived based on the dispersion equation. The new equations are in simple forms similar to the previously reported simplified model with an isotropic substrate. By introducing the Maxwell-Weichert model, these equations are also applicable to the LW device incorporating a viscoelastic guiding layer; the mass velocity sensitivity and the mass propagation loss sensitivity are obtained from the real part and the imaginary part of the complex mass sensitivity, respectively. With Love waves in an elastic SiO2 layer on an ST-90°X quartz structure, for example, comparisons are carried out between the velocities and normalized sensitivities calculated by using different dispersion equations and corresponding mass sensitivities. Numerical results of the method presented in this work are very close to those of the method with a piezoelectric-considered substrate. Another numerical calculation is carried out for the case of a LW sensor with a viscoelastic guiding layer. If the viscosity of the layer is not too big, the effect on the real part of the velocity and the mass velocity sensitivity is relatively small; the propagation loss and the mass loss sensitivity are proportional to the viscosity of the guiding layer.

  6. Cluster abundance in chameleon f(R) gravity I: toward an accurate halo mass function prediction

    Science.gov (United States)

    Cataneo, Matteo; Rapetti, David; Lombriser, Lucas; Li, Baojiu

    2016-12-01

    We refine the mass and environment dependent spherical collapse model of chameleon f(R) gravity by calibrating a phenomenological correction inspired by the parameterized post-Friedmann framework against high-resolution N-body simulations. We employ our method to predict the corresponding modified halo mass function, and provide fitting formulas to calculate the enhancement of the f(R) halo abundance with respect to that of General Relativity (GR) within a precision of lesssim 5% from the results obtained in the simulations. Similar accuracy can be achieved for the full f(R) mass function on the condition that the modeling of the reference GR abundance of halos is accurate at the percent level. We use our fits to forecast constraints on the additional scalar degree of freedom of the theory, finding that upper bounds competitive with current Solar System tests are within reach of cluster number count analyses from ongoing and upcoming surveys at much larger scales. Importantly, the flexibility of our method allows also for this to be applied to other scalar-tensor theories characterized by a mass and environment dependent spherical collapse.

  7. A Statistical Method for Assessing Peptide Identification Confidence in Accurate Mass and Time Tag Proteomics

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, Jeffrey R.; Adkins, Joshua N.; Slysz, Gordon W.; Monroe, Matthew E.; Purvine, Samuel O.; Karpievitch, Yuliya V.; Anderson, Gordon A.; Smith, Richard D.; Dabney, Alan R.

    2011-07-15

    High-throughput proteomics is rapidly evolving to require high mass measurement accuracy for a variety of different applications. Increased mass measurement accuracy in bottom-up proteomics specifically allows for an improved ability to distinguish and characterize detected MS features, which may in turn be identified by, e.g., matching to entries in a database for both precursor and fragmentation mass identification methods. Many tools exist with which to score the identification of peptides from LC-MS/MS measurements or to assess matches to an accurate mass and time (AMT) tag database, but these two calculations remain distinctly unrelated. Here we present a statistical method, Statistical Tools for AMT tag Confidence (STAC), which extends our previous work incorporating prior probabilities of correct sequence identification from LC-MS/MS, as well as the quality with which LC-MS features match AMT tags, to evaluate peptide identification confidence. Compared to existing tools, we are able to obtain significantly more high-confidence peptide identifications at a given false discovery rate and additionally assign confidence estimates to individual peptide identifications. Freely available software implementations of STAC are available in both command line and as a Windows graphical application.

  8. Identification of Microorganisms by High Resolution Tandem Mass Spectrometry with Accurate Statistical Significance

    Science.gov (United States)

    Alves, Gelio; Wang, Guanghui; Ogurtsov, Aleksey Y.; Drake, Steven K.; Gucek, Marjan; Suffredini, Anthony F.; Sacks, David B.; Yu, Yi-Kuo

    2016-02-01

    Correct and rapid identification of microorganisms is the key to the success of many important applications in health and safety, including, but not limited to, infection treatment, food safety, and biodefense. With the advance of mass spectrometry (MS) technology, the speed of identification can be greatly improved. However, the increasing number of microbes sequenced is challenging correct microbial identification because of the large number of choices present. To properly disentangle candidate microbes, one needs to go beyond apparent morphology or simple `fingerprinting'; to correctly prioritize the candidate microbes, one needs to have accurate statistical significance in microbial identification. We meet these challenges by using peptidome profiles of microbes to better separate them and by designing an analysis method that yields accurate statistical significance. Here, we present an analysis pipeline that uses tandem MS (MS/MS) spectra for microbial identification or classification. We have demonstrated, using MS/MS data of 81 samples, each composed of a single known microorganism, that the proposed pipeline can correctly identify microorganisms at least at the genus and species levels. We have also shown that the proposed pipeline computes accurate statistical significances, i.e., E-values for identified peptides and unified E-values for identified microorganisms. The proposed analysis pipeline has been implemented in MiCId, a freely available software for Microorganism Classification and Identification. MiCId is available for download at http://www.ncbi.nlm.nih.gov/CBBresearch/Yu/downloads.html.

  9. SPARC: Mass Models for 175 Disk Galaxies with Spitzer Photometry and Accurate Rotation Curves

    Science.gov (United States)

    Lelli, Federico; McGaugh, Stacy S.; Schombert, James M.

    2016-12-01

    We introduce SPARC (Spitzer Photometry and Accurate Rotation Curves): a sample of 175 nearby galaxies with new surface photometry at 3.6 μm and high-quality rotation curves from previous H i/Hα studies. SPARC spans a broad range of morphologies (S0 to Irr), luminosities (∼5 dex), and surface brightnesses (∼4 dex). We derive [3.6] surface photometry and study structural relations of stellar and gas disks. We find that both the stellar mass–H i mass relation and the stellar radius–H i radius relation have significant intrinsic scatter, while the H i mass–radius relation is extremely tight. We build detailed mass models and quantify the ratio of baryonic to observed velocity (V bar/V obs) for different characteristic radii and values of the stellar mass-to-light ratio (ϒ⋆) at [3.6]. Assuming ϒ⋆ ≃ 0.5 M ⊙/L ⊙ (as suggested by stellar population models), we find that (i) the gas fraction linearly correlates with total luminosity (ii) the transition from star-dominated to gas-dominated galaxies roughly corresponds to the transition from spiral galaxies to dwarf irregulars, in line with density wave theory; and (iii) V bar/V obs varies with luminosity and surface brightness: high-mass, high-surface-brightness galaxies are nearly maximal, while low-mass, low-surface-brightness galaxies are submaximal. These basic properties are lost for low values of ϒ⋆ ≃ 0.2 M ⊙/L ⊙ as suggested by the DiskMass survey. The mean maximum-disk limit in bright galaxies is ϒ⋆ ≃ 0.7 M ⊙/L ⊙ at [3.6]. The SPARC data are publicly available and represent an ideal test bed for models of galaxy formation.

  10. A Lattice Determination of Light Quark Masses

    CERN Document Server

    Göckeler, M; Oelrich, H; Petters, D; Pleiter, D; Rakow, P E L; Schierholz, G; Stephenson, P

    2000-01-01

    A fully non-perturbative lattice determination of the up/down and strange quark masses is given for quenched QCD using both, $O(a)$ improved Wilson fermions and ordinary Wilson fermions. For the strange quark mass with $O(a)$ improved fermions we obtain $m^{\\msbar}_s(\\mu=2 {GeV}) = 105(4) {MeV}$, using the interquark force scale $r_0$. Due to quenching problems fits are only possible for quark masses larger than the strange quark mass. If we extrapolate our fits to the up/down quark mass we find for the average mass $m^{\\msbar}_l(\\mu=2 {GeV}) = 4.4(2) {MeV}$.

  11. Cluster abundance in chameleon $f(R)$ gravity I: toward an accurate halo mass function prediction

    CERN Document Server

    Cataneo, Matteo; Lombriser, Lucas; Li, Baojiu

    2016-01-01

    We refine the mass and environment dependent spherical collapse model of chameleon $f(R)$ gravity by calibrating a phenomenological correction inspired by the parameterized post-Friedmann framework against high-resolution $N$-body simulations. We employ our method to predict the corresponding modified halo mass function, and provide fitting formulas to calculate the fractional enhancement of the $f(R)$ halo abundance with respect to that of General Relativity (GR) within a precision of $\\lesssim 5\\%$ from the results obtained in the simulations. Similar accuracy can be achieved for the full $f(R)$ mass function on the condition that the modeling of the reference GR abundance of halos is accurate at the percent level. We use our fits to forecast constraints on the additional scalar degree of freedom of the theory, finding that upper bounds competitive with current Solar System tests are within reach of cluster number count analyses from ongoing and upcoming surveys at much larger scales. Importantly, the flexi...

  12. Accurate masses of neutron-deficient nuclides close to Z=82

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, S. E-mail: schwarz@nscl.msu.edu; Ames, F.; Audi, G.; Beck, D.; Bollen, G.; De Coster, C.; Dilling, J.; Engels, O.; Fossion, R.; Garcia Ramos, J.-E.; Henry, S.; Herfurth, F.; Heyde, K.; Kellerbauer, A.; Kluge, H.-J.; Kohl, A.; Lamour, E.; Lunney, D.; Martel, I.; Moore, R.B.; Oinonen, M.; Raimbault-Hartmann, H.; Scheidenberger, C.; Sikler, G.; Szerypo, J.; Weber, C

    2001-10-22

    Mass measurements with the Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN are extended to nonsurface ionizable species using newly developed ion-beam bunching devices. Masses of {sup 179-197}Hg, {sup 196,198}Pb, {sup 197}Bi, {sup 198}Po and {sup 203}At were determined with an accuracy of 1x10{sup -7} corresponding to {delta}m{approx}20 keV. Applying a resolving power of up to 3.7x10{sup 6} ground and isomeric states of {sup 185,187,191,193,197}Hg were separated. First experimental values for the isomeric excitation energy of {sup 187,191}Hg are obtained. A least-squares adjustment has been performed and theoretical approaches are discussed to model the observed fine structure in the binding energy.

  13. Accurate mass measurements of very short-lived nuclei. Prerequisites for high-accuracy investigations of superallowed {beta}-decays

    Energy Technology Data Exchange (ETDEWEB)

    Herfurth, F.; Kellerbauer, A.; Sauvan, E. [CERN, 1211 Geneva 23 (Switzerland); Ames, F.; Engels, O. [Sektion Physik, Ludwig-Maximilians-Universitaet Muenchen, 85748 Garching (Germany); Audi, G.; Lunney, D. [CSNSM-IN2P3-CNRS, 91405 Orsay Campus (France); Beck, D.; Blaum, K.; Kluge, H.J.; Scheidenberger, C.; Sikler, G.; Weber, C. [GSI, Planckstrasse 1, 64291 Darmstadt (Germany); Bollen, G.; Schwarz, S. [NSCL, Michigan State University, East Lansing MI 48824-1321 (United States); Moore, R.B. [Department of Physics, McGill University, Montreal (Quebec) H3A 2T8 (Canada); Oinonen, M. [Helsinki Institute of Physics, University of Helsinki, P.O. Box 9, 00014 Helsinki (Finland)

    2002-10-01

    Mass measurements of {sup 34}Ar, {sup 73-78}Kr, and {sup 74,76}Rb were performed with the Penning-trap mass spectrometer ISOLTRAP. Very accurate Q{sub EC}-values are needed for the investigations of the Ft-value of 0{sup +} {yields} 0{sup +} nuclear {beta}-decays used to test the standard model predictions for weak interactions. The necessary accuracy on the Q{sub EC}-value requires the mass of mother and daughter nuclei to be measured with {delta}m/m {<=} 3{sup .}10 {sup -8}. For most of the measured nuclides presented here this has been reached. The {sup 34}Ar mass has been measured with a relative accuracy of 1.1 .10{sup -8}. The Q {sub EC}-value of the {sup 34}Ar 0 {sup +} {yields} 0 {sup +} decay can now be determined with an uncertainty of about 0.01%. Furthermore, {sup 74}Rb is the shortest-lived nuclide ever investigated in a Penning trap. (orig.)

  14. Mass and position determination in MEMS mass sensors: a theoretical and an experimental investigation

    Science.gov (United States)

    Bouchaala, Adam; Nayfeh, Ali H.; Jaber, Nizar; Younis, Mohammad I.

    2016-10-01

    We present a method to determine accurately the position and mass of an entity attached to the surface of an electrostatically actuated clamped-clamped microbeam implemented as a mass sensor. In the theoretical investigation, the microbeam is modeled as a nonlinear Euler-Bernoulli beam and a perturbation technique is used to develop a closed-form expression for the frequency shift due to an added mass at a specific location on the microbeam surface. The experimental investigation was conducted on a microbeam made of Polyimide with a special lower electrode to excite both of the first and second modes of vibration. Using an ink-jet printer, we deposited droplets of polymers with a defined mass and position on the surface of the microbeam and we measured the shifts in its resonance frequencies. The theoretical predictions of the mass and position of the deposited droplets match well with the experimental measurements.

  15. Mass and position determination in MEMS mass sensors: a theoretical and an experimental investigation

    KAUST Repository

    Bouchaala, Adam M.

    2016-08-31

    We present a method to determine accurately the position and mass of an entity attached to the surface of an electrostatically actuated clamped-clamped microbeam implemented as a mass sensor. In the theoretical investigation, the microbeam is modeled as a nonlinear Euler-Bernoulli beam and a perturbation technique is used to develop a closed-form expression for the frequency shift due to an added mass at a specific location on the microbeam surface. The experimental investigation was conducted on a microbeam made of Polyimide with a special lower electrode to excite both of the first and second modes of vibration. Using an ink-jet printer, we deposited droplets of polymers with a defined mass and position on the surface of the microbeam and we measured the shifts in its resonance frequencies. The theoretical predictions of the mass and position of the deposited droplets match well with the experimental measurements.

  16. How To Determine SUSY Mass Scales Now

    CERN Document Server

    Heinemeyer, S

    2008-01-01

    Currently available experimental data from electroweak precision observables (EWPO), B-physics observables (BPO) and cosmological data can be combined to extract the preferred value of SUSY mass scales. We review recent results on the predictions of the masses of supersymmetric particles and the indirect determination of the lightest Higgs boson mass. Special emphasis is put on models going beyond the Constrained Minimal Supersymmetric Standard Model (CMSSM), such as the Non-Universal Higgs Model type I (NUHM1), or gauge and anomaloy mediated SUSY breaking.

  17. How To Determine SUSY Mass Scales Now

    Science.gov (United States)

    Heinemeyer, S.

    2008-11-01

    Currently available experimental data from electroweak precision observables (EWPO), B-physics observables (BPO) and cosmological data can be combined to extract the preferred value of SUSY mass scales. We review recent results on the predictions of the masses of supersymmetric particles and the indirect determination of the lightest Higgs boson mass. Special emphasis is put on models going beyond the Constrained Minimal Supersymmetric Standard Model (CMSSM), such as the Non-Universal Higgs Model type I (NUHM1), or gauge and anomaloy mediated SUSY breaking.

  18. Indirect determinations of the top quark mass

    CERN Document Server

    Giudice, Gian F; Strumia, Alessandro

    2015-01-01

    We give a complete analysis of indirect determinations of the top quark mass in the Standard Model by introducing a systematic procedure to identify observables that receive quantum corrections enhanced by powers of $M_t$. We propose to use flavour physics as a tool to extract the top quark mass. Although present data give only a poor determination, we show how future theoretical and experimental progress in flavour physics can lead to an accuracy in $M_t$ well below 2 GeV. We revisit determinations of $M_t$ from electroweak data, showing how an improved measurement of the $W$ mass leads to an accuracy well below 1 GeV.

  19. Fatty acids composition of Caenorhabditis elegans using accurate mass GCMS-QTOF.

    Science.gov (United States)

    Henry, Parise; Owopetu, Olufunmilayo; Adisa, Demilade; Nguyen, Thao; Anthony, Kevin; Ijoni-Animadu, David; Jamadar, Sakha; Abdel-Rahman, Fawzia; Saleh, Mahmoud A

    2016-08-02

    The free living nematode Caenorhabditis elegans is a proven model organism for lipid metabolism research. Total lipids of C. elegans were extracted using chloroform and methanol in 2:1 ratio (v/v). Fatty acids composition of the extracted total lipids was converted to their corresponding fatty acids methyl esters (FAMEs) and analyzed by gas chromatography/accurate mass quadrupole time of flight mass spectrometry using both electron ionization and chemical ionization techniques. Twenty-eight fatty acids consisting of 12 to 22 carbon atoms were identified, 65% of them were unsaturated. Fatty acids containing 12 to17 carbons were mostly saturated with stearic acid (18:0) as the major constituent. Several branched-chain fatty acids were identified. Methyl-14-methylhexadecanoate (iso- 17:0) was the major identified branched fatty acid. This is the first report to detect the intact molecular parent ions of the identified fatty acids in C. elegans using chemical ionization compared to electron ionization which produced fragmentations of the FAMEs.

  20. Galaxy And Mass Assembly (GAMA): Accurate Panchromatic Photometry from Optical Priors using LAMBDAR

    CERN Document Server

    Wright, A H; Bourne, N; Driver, S P; Dunne, L; Maddox, S J; Alpaslan, M; Andrews, S K; Bauer, A E; Bland-Hawthorn, J; Brough, S; Brown, M J I; Cluver, M; Davies, L J M; Holwerda, B W; Hopkins, A M; Jarrett, T H; Kafle, P R; Lange, R; Liske, J; Loveday, J; Moffett, A J; Norberg, P; Popescu, C C; Smith, M; Taylor, E N; Tuffs, R J; Wang, L; Wilkins, S M

    2016-01-01

    We present the Lambda Adaptive Multi-Band Deblending Algorithm in R (LAMBDAR), a novel code for calculating matched aperture photometry across images that are neither pixel- nor PSF-matched, using prior aperture definitions derived from high resolution optical imaging. The development of this program is motivated by the desire for consistent photometry and uncertainties across large ranges of photometric imaging, for use in calculating spectral energy distributions. We describe the program, specifically key features required for robust determination of panchromatic photometry: propagation of apertures to images with arbitrary resolution, local background estimation, aperture normalisation, uncertainty determination and propagation, and object deblending. Using simulated images, we demonstrate that the program is able to recover accurate photometric measurements in both high-resolution, low-confusion, and low-resolution, high-confusion, regimes. We apply the program to the 21-band photometric dataset from the ...

  1. Applicability of CFD Modelling in Determining Accurate Weir Discharge: Water Level Relationships

    NARCIS (Netherlands)

    Rombouts, P.M.M.; Tralli, A.; Langeveld, J.G.; Verhaart, F.; Clemens, F.H.L.R.

    2014-01-01

    Being able to accurately determine weir discharges is of key importance in urban water management. The most common method is performing a level measurement and calculating the discharge using the standard weir equation. Since this equation is only valid in certain conditions, this can lead to large

  2. On canonical cylinder sections for accurate determination of contact angle in microgravity

    Science.gov (United States)

    Concus, Paul; Finn, Robert; Zabihi, Farhad

    1992-01-01

    Large shifts of liquid arising from small changes in certain container shapes in zero gravity can be used as a basis for accurately determining contact angle. Canonical geometries for this purpose, recently developed mathematically, are investigated here computationally. It is found that the desired nearly-discontinuous behavior can be obtained and that the shifts of liquid have sufficient volume to be readily observed.

  3. Accurate determination of process variables in a solid-state fermentation system

    NARCIS (Netherlands)

    Smits, J.P.; Rinzema, A.; Tramper, J.; Schlösser, E.E.; Knol, W.

    1996-01-01

    The solid-state fermentation (SSF) method described enabled accurate determination of variables related to biological activity. Growth, respiratory activity and production of carboxymethyl-cellulose-hydrolysing enzyme (CMC-ase) activity by Trichoderma reesei QM9414 on wheat bran was used as a model

  4. Identification of Novel Perfluoroalkyl Ether Carboxylic Acids (PFECAs) and Sulfonic Acids (PFESAs) in Natural Waters Using Accurate Mass Time-of-Flight Mass Spectrometry (TOFMS).

    Science.gov (United States)

    Strynar, Mark; Dagnino, Sonia; McMahen, Rebecca; Liang, Shuang; Lindstrom, Andrew; Andersen, Erik; McMillan, Larry; Thurman, Michael; Ferrer, Imma; Ball, Carol

    2015-10-06

    Recent scientific scrutiny and concerns over exposure, toxicity, and risk have led to international regulatory efforts resulting in the reduction or elimination of certain perfluorinated compounds from various products and waste streams. Some manufacturers have started producing shorter chain per- and polyfluorinated compounds to try to reduce the potential for bioaccumulation in humans and wildlife. Some of these new compounds contain central ether oxygens or other minor modifications of traditional perfluorinated structures. At present, there has been very limited information published on these "replacement chemistries" in the peer-reviewed literature. In this study we used a time-of-flight mass spectrometry detector (LC-ESI-TOFMS) to identify fluorinated compounds in natural waters collected from locations with historical perfluorinated compound contamination. Our workflow for discovery of chemicals included sequential sampling of surface water for identification of potential sources, nontargeted TOFMS analysis, molecular feature extraction (MFE) of samples, and evaluation of features unique to the sample with source inputs. Specifically, compounds were tentatively identified by (1) accurate mass determination of parent and/or related adducts and fragments from in-source collision-induced dissociation (CID), (2) in-depth evaluation of in-source adducts formed during analysis, and (3) confirmation with authentic standards when available. We observed groups of compounds in homologous series that differed by multiples of CF2 (m/z 49.9968) or CF2O (m/z 65.9917). Compounds in each series were chromatographically separated and had comparable fragments and adducts produced during analysis. We detected 12 novel perfluoroalkyl ether carboxylic and sulfonic acids in surface water in North Carolina, USA using this approach. A key piece of evidence was the discovery of accurate mass in-source n-mer formation (H(+) and Na(+)) differing by m/z 21.9819, corresponding to the

  5. Screening in veterinary drug analysis and sports doping control based on full-scan, accurate-mass spectrometry

    NARCIS (Netherlands)

    Peters, R.J.B.; Stolker, A.A.M.; Mol, J.G.J.; Lommen, A.; Lyris, E.; Angelis, Y.S.; Vonaparti, A.; Stamou, M.; Georgakopoulos, C.G.; Nielen, M.W.F.

    2010-01-01

    A common trend in food contaminants and sports doping control is towards a limited number of targeted, full-scan, accurate-mass spectrometry (MS) methods based on time-of-flight (TOF) or Fourier-transform orbital trap (Orbitrap) mass analyzers. Retrospective analysis of the full-scan datasets of sig

  6. Does turbulence determine the initial mass function?

    CERN Document Server

    Liptai, David; Wurster, James; Bate, Matthew R

    2016-01-01

    We test the hypothesis that the initial mass function (IMF) is determined by the density probability distribution function (PDF) produced by supersonic turbulence. We compare 14 simulations of star cluster formation in 50 solar mass molecular cloud cores where the initial turbulence contains either purely solenoidal or purely compressive modes, in each case resolving fragmentation to the opacity limit to determine the resultant IMF. We find statistically indistinguishable IMFs between the two sets of calculations, despite a factor of two difference in the star formation rate and in the standard deviation of $\\log(\\rho)$. This suggests that the density PDF, while determining the star formation rate, is not the primary driver of the IMF.

  7. Does turbulence determine the initial mass function?

    Science.gov (United States)

    Liptai, David; Price, Daniel J.; Wurster, James; Bate, Matthew R.

    2017-02-01

    We test the hypothesis that the initial mass function (IMF) is determined by the density probability distribution function (PDF) produced by supersonic turbulence. We compare 14 simulations of star cluster formation in 50 M⊙ molecular cloud cores where the initial turbulence contains either purely solenoidal or purely compressive modes, in each case resolving fragmentation to the opacity limit to determine the resultant IMF. We find statistically indistinguishable IMFs between the two sets of calculations, despite a factor of 2 difference in the star formation rate and in the standard deviation of log (ρ). This suggests that the density PDF, while determining the star formation rate, is not the primary driver of the IMF.

  8. Interference-aided spectrum fitting method for accurately film thickness determination

    CERN Document Server

    Liu, Xingxing; Xia, Hui; Zhang, Xutao; Ji, Ruonan; Li, Tianxin; Lu, Wei

    2016-01-01

    A new approach was proposed to accurately determine the thickness of film, especially for ultra-thin film, through spectrum fitting with the assistance of interference layer. The determination limit can reach even less than 1 nm. Its accuracy is far better than traditional methods. This determination method is verified by experiments and the determination limit is at least 3.5 nm compared with the results of AFM. Furthermore, double-interference-aided spectra fitting method is proposed to reduce the requirements of determination instruments, which allow one to determine the film thickness with a low precision common spectrometer and largely lower the cost. It is a very high precision determination method for on-site and in-situ applications, especially for ultra-thin films.

  9. Spectroscopic determination of masses (and implied ages) for red giants

    CERN Document Server

    Ness, M; Rix, H-W; Martig, M; Pinsonneault, Marc H; Ho, A Y Q

    2015-01-01

    The mass of a star is arguably its most fundamental parameter. For red giant stars, tracers luminous enough to be observed across the Galaxy, mass implies a stellar evolution age. It has proven to be extremely difficult to infer ages and masses directly from red giant spectra using existing methods. From the KEPLER and APOGEE surveys, samples of several thousand stars exist with high-quality spectra and asteroseismic masses. Here we show that from these data we can build a data-driven spectral model using The Cannon, which can determine stellar masses to $\\sim$ 0.07 dex from APOGEE DR12 spectra of red giants; these imply age estimates accurate to $\\sim$ 0.2 dex (40 percent). We show that The Cannon constrains these ages foremost from spectral regions with CN absorption lines, elements whose surface abundances reflect mass-dependent dredge-up. We deliver an unprecedented catalog of 80,000 giants (including 20,000 red-clump stars) with mass and age estimates, spanning the entire disk (from the Galactic center t...

  10. Strategies for an accurate determination of the X(3872) energy from QCD lattice simulations

    CERN Document Server

    Garzon, E J; Hosaka, A; Oset, E

    2015-01-01

    We develop a method to determine accurately the binding energy of the X(3872) from lattice data for the DD* interaction. We show that, because of the small difference between the neutral and charged components of the X(3872), it is necessary to distinguish them in the energy levels of the lattice spectrum if one wishes to have a precise determination of the the binding energy of the X(3872). The analysis of the data requires the use of coupled channels. Depending on the number of levels available and the size of the box we determine the precision needed in the lattice energies to finally obtain a desired accuracy in the binding energy.

  11. Biases on Initial Mass Function Determinations. III. Cluster Masses Derived from Unresolved Photometry

    Science.gov (United States)

    Maíz Apellániz, J.

    2009-07-01

    It is currently common to use spatially unresolved multifilter broadband photometry to determine the masses of individual stellar clusters (and hence the cluster mass function, CMF). I analyze the stochastic effects introduced by the sampling of the stellar initial mass function (SIMF) in the derivation of the individual masses and the CMF, and I establish that such effects are the largest contributor to the observational uncertainties. An analytical solution, valid in the limit where uncertainties are small, is provided to establish the range of cluster masses over which the CMF slope can be obtained with a given accuracy. The validity of the analytical solution is extended to higher mass uncertainties using Monte Carlo simulations and the Gamma approximation. The value of the Poisson mass is calculated for a large range of ages and a variety of filters for solar-metallicity clusters measured with single-filter photometry. A method that uses the code CHORIZOS is presented to simultaneously derive masses, ages, and extinctions. The classical method of using unweighted UBV photometry to simultaneously establish ages and extinctions of stellar clusters is found to be unreliable for clusters older than ≈30 Ma, even for relatively large cluster masses. On the other hand, augmenting the filter set to include longer-wavelength filters and using weights for each filter increases the range of masses and ages that can be accurately measured with unresolved photometry. Nevertheless, a relatively large range of masses and ages is found to be dominated by SIMF sampling effects that render the observed masses useless, even when using UBVRIJHK photometry. A revision of some literature results affected by these effects is presented and possible solutions for future observations and analyses are suggested.

  12. An Iterative Fingerprint Enhancement Algorithm Based on Accurate Determination of Orientation Flow

    CERN Document Server

    Dube, Simant

    2009-01-01

    We describe an algorithm to enhance and binarize a fingerprint image. The algorithm is based on accurate determination of orientation flow of the ridges of the fingerprint image by computing variance of the neighborhood pixels around a pixel in different directions. We show that an iterative algorithm which captures the mutual interdependence of orientation flow computation, enhancement and binarization gives very good results on poor quality images.

  13. Incentives Increase Participation in Mass Dog Rabies Vaccination Clinics and Methods of Coverage Estimation Are Assessed to Be Accurate.

    Directory of Open Access Journals (Sweden)

    Abel B Minyoo

    2015-12-01

    Full Text Available In this study we show that incentives (dog collars and owner wristbands are effective at increasing owner participation in mass dog rabies vaccination clinics and we conclude that household questionnaire surveys and the mark-re-sight (transect survey method for estimating post-vaccination coverage are accurate when all dogs, including puppies, are included. Incentives were distributed during central-point rabies vaccination clinics in northern Tanzania to quantify their effect on owner participation. In villages where incentives were handed out participation increased, with an average of 34 more dogs being vaccinated. Through economies of scale, this represents a reduction in the cost-per-dog of $0.47. This represents the price-threshold under which the cost of the incentive used must fall to be economically viable. Additionally, vaccination coverage levels were determined in ten villages through the gold-standard village-wide census technique, as well as through two cheaper and quicker methods (randomized household questionnaire and the transect survey. Cost data were also collected. Both non-gold standard methods were found to be accurate when puppies were included in the calculations, although the transect survey and the household questionnaire survey over- and under-estimated the coverage respectively. Given that additional demographic data can be collected through the household questionnaire survey, and that its estimate of coverage is more conservative, we recommend this method. Despite the use of incentives the average vaccination coverage was below the 70% threshold for eliminating rabies. We discuss the reasons and suggest solutions to improve coverage. Given recent international targets to eliminate rabies, this study provides valuable and timely data to help improve mass dog vaccination programs in Africa and elsewhere.

  14. Accurate measurements of {sup 129}I concentration by isotope dilution using MC-ICPMS for half-life determination

    Energy Technology Data Exchange (ETDEWEB)

    Isnard, Helene; Nonell, Anthony; Marie, Mylene [Commissariat a l' Energie Atomique et aux Energies alternatives (CEA), Gif Sur Yvette (France). DEN, DPC, SEARS, LANIE; Chartier, Frederic [Commissariat a l' Energie Atomique et aux Energies alternatives (CEA), Gif Sur Yvette (France). DEN, DPC

    2016-05-01

    Determining the {sup 129}I concentration, a long-lived radionuclide present in spent nuclear fuel, is a major issue for nuclear waste disposal purpose. {sup 129}I also has to be measured in numerous environmental, nuclear and biological samples. To be able to accurately determine the {sup 129}I concentration, an analytical method based on the use of a multicollector-inductively coupled plasma mass spectrometer (MC-ICPMS) combined with an isotope dilution technique using an {sup 127}I spike, was developed. First, the influence of different media (HNO{sub 3}, NaOH and TMAH) on natural {sup 127}I signal intensity and stability and on memory effects was studied. Then an analytical procedure was developed by taking into account the correction of blanks and interferences. Tellurium was chosen for instrumental mass bias correction, as no certified standards with suitable {sup 127}I/{sup 129}I ratio are available. Finally, the results, reproducibility and uncertainties obtained for the {sup 129}I concentration determined by isotope dilution with a {sup 127}I spike are presented and discussed. The final expanded relative uncertainty obtained for the iodine-129 concentration was lower than 0.7% (k = 1). This precise {sup 129}I determination in association with further activity measurements of this nuclide on the same sample will render it possible to determine a new value of the {sup 129}I half-life with a reduced uncertainty (0.76%, k = 1).

  15. Accurate determination of aldehydes in amine catalysts or amines by 2,4-dinitrophenylhydrazine derivatization.

    Science.gov (United States)

    Barman, Bhajendra N

    2014-01-31

    Carbonyl compounds, specifically aldehydes, present in amine catalysts or amines are determined by reversed-phase liquid chromatography using ultraviolet detection of their corresponding 2,4-dinitrophenylhydrazones. The primary focus has been to establish optimum conditions for determining aldehydes accurately because these add exposure concerns when the amine catalysts are used to manufacture polyurethane products. Concentrations of aldehydes determined by this method are found to vary with the pH of the aqueous amine solution and the derivatization time, the latter being problematic when the derivatization reaction proceeds slowly and not to completion in neutral and basic media. Accurate determination of aldehydes in amines through derivatization can be carried out at an effective solution pH of about 2 and with derivatization time of 20min. Hydrochloric acid has been used for neutralization of an amine. For complete derivatization, it is essential to protonate all nitrogen atoms in the amine. An approach for the determination of an adequate amount of acid needed for complete derivatization has been described. Several 0.2M buffer solutions varying in pH from 4 to 8 have also been used to make amine solutions for carrying out derivatization of aldehydes. These solutions have effective pHs of 10 or higher and provide much lower aldehyde concentrations compared to their true values. Mechanisms for the formation of 2,4-dinitrophenylhydrazones in both acidic and basic media are discussed.

  16. Accurate Quantification of Lipid Species by Electrospray Ionization Mass Spectrometry — Meets a Key Challenge in Lipidomics

    Directory of Open Access Journals (Sweden)

    Kui Yang

    2011-11-01

    Full Text Available Electrospray ionization mass spectrometry (ESI-MS has become one of the most popular and powerful technologies to identify and quantify individual lipid species in lipidomics. Meanwhile, quantitative analysis of lipid species by ESI-MS has also become a major obstacle to meet the challenges of lipidomics. Herein, we discuss the principles, advantages, and possible limitations of different mass spectrometry-based methodologies for lipid quantification, as well as a few practical issues important for accurate quantification of individual lipid species. Accordingly, accurate quantification of individual lipid species, one of the key challenges in lipidomics, can be practically met.

  17. A highly accurate method for determination of dissolved oxygen: gravimetric Winkler method.

    Science.gov (United States)

    Helm, Irja; Jalukse, Lauri; Leito, Ivo

    2012-09-05

    A high-accuracy Winkler titration method has been developed for determination of dissolved oxygen concentration. Careful analysis of uncertainty sources relevant to the Winkler method was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. The most important improvements were: gravimetric measurement of all solutions, pre-titration to minimize the effect of iodine volatilization, accurate amperometric end point detection and careful accounting for dissolved oxygen in the reagents. As a result, the developed method is possibly the most accurate method of determination of dissolved oxygen available. Depending on measurement conditions and on the dissolved oxygen concentration the combined standard uncertainties of the method are in the range of 0.012-0.018 mg dm(-3) corresponding to the k=2 expanded uncertainty in the range of 0.023-0.035 mg dm(-3) (0.27-0.38%, relative). This development enables more accurate calibration of electrochemical and optical dissolved oxygen sensors for routine analysis than has been possible before.

  18. Accurate determination of DNA yield from individual mosquitoes for population genomic applications

    Institute of Scientific and Technical Information of China (English)

    Craig S.Wilding; D.Weetman; K.Steen; M.J.Donnelly

    2009-01-01

    Accurate estimates of DNA quantity are likely to become increasingly important for successful genomic screening of insect populations via recently developed, highly multiplexed genotyping assays and high-throughput sequencing methods. Here we show that genomic DNA extractions from single Anopheles gambiae Giles using a standard commercial kit-based methodology yield extracts with concentrations below the linear range of spectrophotometric absorbance at 260 nm. Concentrations determined by spectrophotometry were not reproducible, and are therefore neither accurate nor reliable. However,DNA quantification using a fluorescent nucleic acid stain (PicoGreenR) gave highly reproducible concentration estimates, and indicated that, on average, single mosquitoes yielded approximately 300 ng of DNA. Such a total yield is currently insufficient for many highthroughput genome screening applications, necessitating whole genome amplification of all or most individuals in a population prior to genotyping.

  19. Simultaneous measurement in mass and mass/mass mode for accurate qualitative and quantitative screening analysis of pharmaceuticals in river water.

    Science.gov (United States)

    Martínez Bueno, M J; Ulaszewska, Maria M; Gomez, M J; Hernando, M D; Fernández-Alba, A R

    2012-09-21

    A new approach for the analysis of pharmaceuticals (target and non-target) in water by LC-QTOF-MS is described in this work. The study has been designed to assess the performance of the simultaneous quantitative screening of target compounds, and the qualitative analysis of non-target analytes, in just one run. The features of accurate mass full scan mass spectrometry together with high MS/MS spectral acquisition rates - by means of information dependent acquisition (IDA) - have demonstrated their potential application in this work. Applying this analytical strategy, an identification procedure is presented based on library searching for compounds which were not included a priori in the analytical method as target compounds, thus allowing their characterization by data processing of accurate mass measurements in MS and MS/MS mode. The non-target compounds identified in river water samples were ketorolac, trazodone, fluconazole, metformin and venlafaxine. Simultaneously, this strategy allowed for the identification of other compounds which were not included in the library by screening the highest intensity peaks detected in the samples and by analysis of the full scan TOF-MS, isotope pattern and MS/MS spectra - the example of loratadine (histaminergic) is described. The group of drugs of abuse selected as target compounds for evaluation included analgesics, opioids and psychostimulants. Satisfactory results regarding sensitivity and linearity of the developed method were obtained. Limits of detection for the selected target compounds were from 0.003 to 0.01 μg/L and 0.01 to 0.5 μg/L, in MS and MS/MS mode, respectively - by direct sample injection of 100 μL.

  20. Accurate screening for synthetic preservatives in beverage using high performance liquid chromatography with time-of-flight mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiuqin; Zhang Feng; Sun Yanyan; Yong Wei [Institute of Food Safety, Chinese Academy of Inspection and Quarantine, Jia 3, Gaobeidian North Road, Beijing 100025 (China); Chu Xiaogang [Institute of Food Safety, Chinese Academy of Inspection and Quarantine, Jia 3, Gaobeidian North Road, Beijing 100025 (China)], E-mail: lixq_sypu@yahoo.com; Fang Yanyan; Zweigenbaum, Jerry [Agilent Technologies, Inc., 2850 Centerville Road, Wilmington, Delaware (United States)

    2008-02-11

    In this study, liquid chromatography time-of-flight mass spectrometry (HPLC/TOF-MS) is applied to qualitation and quantitation of 18 synthetic preservatives in beverage. The identification by HPLC/TOF-MS is accomplished with the accurate mass (the subsequent generated empirical formula) of the protonated molecules [M + H]+ or the deprotonated molecules [M - H]-, along with the accurate mass of their main fragment ions. In order to obtain sufficient sensitivity for quantitation purposes (using the protonated or deprotonated molecule) and additional qualitative mass spectrum information provided by the fragments ions, segment program of fragmentor voltages is designed in positive and negative ion mode, respectively. Accurate mass measurements are highly useful in the complex sample analyses since they allow us to achieve a high degree of specificity, often needed when other interferents are present in the matrix. The mass accuracy typically obtained is routinely better than 3 ppm. The 18 compounds behave linearly in the 0.005-5.0 mg.kg{sup -1} concentration range, with correlation coefficient >0.996. The recoveries at the tested concentrations of 1.0 mg.kg{sup -1}-100 mg.kg{sup -1} are 81-106%, with coefficients of variation <7.5%. Limits of detection (LODs) range from 0.0005 to 0.05 mg.kg{sup -1}, which are far below the required maximum residue level (MRL) for these preservatives in foodstuff. The method is suitable for routine quantitative and qualitative analyses of synthetic preservatives in foodstuff.

  1. Accurate screening for synthetic preservatives in beverage using high performance liquid chromatography with time-of-flight mass spectrometry.

    Science.gov (United States)

    Li, Xiu Qin; Zhang, Feng; Sun, Yan Yan; Yong, Wei; Chu, Xiao Gang; Fang, Yan Yan; Zweigenbaum, Jerry

    2008-02-11

    In this study, liquid chromatography time-of-flight mass spectrometry (HPLC/TOF-MS) is applied to qualitation and quantitation of 18 synthetic preservatives in beverage. The identification by HPLC/TOF-MS is accomplished with the accurate mass (the subsequent generated empirical formula) of the protonated molecules [M+H]+ or the deprotonated molecules [M-H]-, along with the accurate mass of their main fragment ions. In order to obtain sufficient sensitivity for quantitation purposes (using the protonated or deprotonated molecule) and additional qualitative mass spectrum information provided by the fragments ions, segment program of fragmentor voltages is designed in positive and negative ion mode, respectively. Accurate mass measurements are highly useful in the complex sample analyses since they allow us to achieve a high degree of specificity, often needed when other interferents are present in the matrix. The mass accuracy typically obtained is routinely better than 3 ppm. The 18 compounds behave linearly in the 0.005-5.0mg.kg(-1) concentration range, with correlation coefficient >0.996. The recoveries at the tested concentrations of 1.0mg.kg(-1)-100mg.kg(-1) are 81-106%, with coefficients of variation preservatives in foodstuff. The method is suitable for routine quantitative and qualitative analyses of synthetic preservatives in foodstuff.

  2. Accurate determination of the Boltzmann constant by Doppler spectroscopy: Towards a new definition of the kelvin

    CERN Document Server

    Darquié, Benoît; Sow, Papa Lat Tabara; Lemarchand, Cyril; Triki, Meriam; Tokunaga, Sean; Bordé, Christian J; Chardonnet, Christian; Daussy, Christophe

    2015-01-01

    Accurate molecular spectroscopy in the mid-infrared region allows precision measurements of fundamental constants. For instance, measuring the linewidth of an isolated Doppler-broadened absorption line of ammonia around 10 $\\mu$m enables a determination of the Boltzmann constant k B. We report on our latest measurements. By fitting this lineshape to several models which include Dicke narrowing or speed-dependent collisional effects, we find that a determination of k B with an uncertainty of a few ppm is reachable. This is comparable to the best current uncertainty obtained using acoustic methods and would make a significant contribution to any new value of k B determined by the CODATA. Furthermore, having multiple independent measurements at these accuracies opens the possibility of defining the kelvin by fixing k B, an exciting prospect considering the upcoming redefinition of the International System of Units.

  3. Accurate determination of the Boltzmann constant by Doppler spectroscopy: Towards a new definition of the kelvin

    Directory of Open Access Journals (Sweden)

    Darquié Benoît

    2013-08-01

    Full Text Available Accurate molecular spectroscopy in the mid-infrared region allows precision measurements of fundamental constants. For instance, measuring the linewidth of an isolated Doppler-broadened absorption line of ammonia around 10 μm enables a determination of the Boltzmann constant kB. We report on our latest measurements. By fitting this lineshape to several models which include Dicke narrowing or speed-dependent collisional effects, we find that a determination of kB with an uncertainty of a few ppm is reachable. This is comparable to the best current uncertainty obtained using acoustic methods and would make a significant contribution to any new value of kB determined by the CODATA. Furthermore, having multiple independent measurements at these accuracies opens the possibility of defining the kelvin by fixing kB, an exciting prospect considering the upcoming redefinition of the International System of Units.

  4. Fragmentation pathways of drugs of abuse and their metabolites based on QTOF MS/MS and MSE accurate-mass spectra

    OpenAIRE

    2011-01-01

    A study of the fragmentation pathways of several classes of drugs of abuse (cannabinoids, ketamine, amphetamine and amphetamine-type stimulants (ATS), cocaine and opiates) and their related substances has been made. The knowledge of the fragmentation is highly useful for specific fragment selection or for recognition of related compounds when developing MS-based analytical methods for the trace-level determination of these compounds in complex matrices. In this work, accurate-mass spectra of ...

  5. A powerful test of independent assortment that determines genome-wide significance quickly and accurately.

    Science.gov (United States)

    Stewart, W C L; Hager, V R

    2016-08-01

    In the analysis of DNA sequences on related individuals, most methods strive to incorporate as much information as possible, with little or no attention paid to the issue of statistical significance. For example, a modern workstation can easily handle the computations needed to perform a large-scale genome-wide inheritance-by-descent (IBD) scan, but accurate assessment of the significance of that scan is often hindered by inaccurate approximations and computationally intensive simulation. To address these issues, we developed gLOD-a test of co-segregation that, for large samples, models chromosome-specific IBD statistics as a collection of stationary Gaussian processes. With this simple model, the parametric bootstrap yields an accurate and rapid assessment of significance-the genome-wide corrected P-value. Furthermore, we show that (i) under the null hypothesis, the limiting distribution of the gLOD is the standard Gumbel distribution; (ii) our parametric bootstrap simulator is approximately 40 000 times faster than gene-dropping methods, and it is more powerful than methods that approximate the adjusted P-value; and, (iii) the gLOD has the same statistical power as the widely used maximum Kong and Cox LOD. Thus, our approach gives researchers the ability to determine quickly and accurately the significance of most large-scale IBD scans, which may contain multiple traits, thousands of families and tens of thousands of DNA sequences.

  6. Accurate bulk density determination of irregularly shaped translucent and opaque aerogels

    Science.gov (United States)

    Petkov, M. P.; Jones, S. M.

    2016-05-01

    We present a volumetric method for accurate determination of bulk density of aerogels, calculated from extrapolated weight of the dry pure solid and volume estimates based on the Archimedes' principle of volume displacement, using packed 100 μm-sized monodispersed glass spheres as a "quasi-fluid" media. Hard particle packing theory is invoked to demonstrate the reproducibility of the apparent density of the quasi-fluid. Accuracy rivaling that of the refractive index method is demonstrated for both translucent and opaque aerogels with different absorptive properties, as well as for aerogels with regular and irregular shapes.

  7. Techniques for determining propulsion system forces for accurate high speed vehicle drag measurements in flight

    Science.gov (United States)

    Arnaiz, H. H.

    1975-01-01

    As part of a NASA program to evaluate current methods of predicting the performance of large, supersonic airplanes, the drag of the XB-70 airplane was measured accurately in flight at Mach numbers from 0.75 to 2.5. This paper describes the techniques used to determine engine net thrust and the drag forces charged to the propulsion system that were required for the in-flight drag measurements. The accuracy of the measurements and the application of the measurement techniques to aircraft with different propulsion systems are discussed. Examples of results obtained for the XB-70 airplane are presented.

  8. Isotope determination of sulfur by mass spectrometry in soil samples

    Directory of Open Access Journals (Sweden)

    Alexssandra Luiza Rodrigues Molina Rossete

    2012-12-01

    Full Text Available Sulphur plays an essential role in plants and is one of the main nutrients in several metabolic processes. It has four stable isotopes (32S, 33S, 34S, and 36S with a natural abundance of 95.00, 0.76, 4.22, and 0.014 in atom %, respectively. A method for isotopic determination of S by isotope-ratio mass spectrometry (IRMS in soil samples is proposed. The procedure involves the oxidation of organic S to sulphate (S-SO4(2-, which was determined by dry combustion with alkaline oxidizing agents. The total S-SO4(2- concentration was determined by turbidimetry and the results showed that the conversion process was adequate. To produce gaseous SO2 gas, BaSO4 was thermally decomposed in a vacuum system at 900 ºC in the presence of NaPO3. The isotope determination of S (atom % 34S atoms was carried out by isotope ratio mass spectrometry (IRMS. In this work, the labeled material (K2(34SO4 was used to validate the method of isotopic determination of S; the results were precise and accurate, showing the viability of the proposed method.

  9. History and progress in the accurate determination of the Avogadro constant

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Peter [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    2001-12-01

    The Avogadro constant, N{sub A}, is a fundamental physical constant that relates any quantity at the atomic scale to its corresponding macroscopic scale. Inspired by the kinetic gas theory Avogadro proposed his hypothesis in 1811, in order to describe chemical reactions as an atomic process between atoms or molecules. Starting from his pioneering findings, the determination of this large number has fascinated generations of scientists up to this day. The review of methods aimed at finding a value for N{sub A} starts with the calculations made by Loschmidt (1865; N{sub A}{approx}72x10{sup 23} mol{sup -1}) who evaluated the number of molecules in a given gas volume, derived from estimates of molecular diameters and the mean free path length. Consideration of Brownian motion led to some more accurate determinations of N{sub A} around the beginning of the 20th century (Perrin (1908); N{sub A}{approx}6.7x10{sup 23} mol{sup -1}). Other methods developed in the following years are based on Millikan's oil drop experiment (1917, N{sub A}{approx}6.064(6)x10{sup 23} mol{sup -1}), on the counting of alpha particles emitted from radium or uranium (Rutherford (1909); N{sub A}{approx}6.16x10{sup 23} mol{sup -1}) and on investigations of molecular monolayers on liquids (Nuoy (1924); N{sub A}{approx}6.004x10{sup 23} mol{sup -1}). A modern method to derive N{sub A} from the density, the relative atomic mass, and the unit cell length was introduced by Bragg in 1913. It makes use of the diffraction of x-rays by the interatomic spacings of a crystal lattice and its periodic arrangement. The accuracy of this method is extremely affected by the fact that the lattice scale of the structurally imperfect lattice can be calibrated only approximately in SI units. Data of NA were, therefore, found to be in disagreement with other fundamental constants (Bearden (1931); N{sub A}{approx}6.019(3)x10{sup 23} mol{sup -1}). A break though was achieved with perfect crystals of silicon and x

  10. Physical consequences of the alpha/beta rule which accurately calculates particle masses

    Energy Technology Data Exchange (ETDEWEB)

    Greulich, Karl Otto [Fritz Lipmann Institute, Beutenbergstr.11, D07745 Jena (Germany)

    2015-07-01

    Using the fine structure constant α (=1/137.036), the proton vs. electron mass ratio β (= 1836.2) and the integers m and n, the α/β rule: m{sub particle} = α{sup -n} x β m x 27.2 eV/c{sup 2} allows almost exact calculation of particle masses. (K.O.Greulich, DPG Spring meeting 2014, Mainz, T99.4) With n=2, m=0 the electron mass becomes 510.79 keV/c{sup 2} (experimental 511 keV/c{sup 2}) With n=2, m=1 the proton mass is 937.9 MeV/c{sup 2} (literature 938.3 MeV/c{sup 2}). For n=3 and m=1 a particle with 128.6 GeV/c{sup 2} close to the reported Higgs mass, is expected. For n=14 and m=-1 the Planck mass results. The calculated masses for gauge bosons and for quarks have similar accuracy. All masses fit into the same scheme (the alpha/beta rule), indicating that non of these particle masses play an extraordinary role. Particularly, the Higgs Boson, often termed the *God particle* plays in this sense no extraordinary role. In addition, particle masses are intimately correlated with the fine structure constant α. If particle masses have been constant over all times, α must have been constant over these times. In addition, the ionization energy of the hydrogen atom (13.6 eV) needs to have been constant if particle masses have been unchanged or vice versa. In conclusion, the α/β rule needs to be taken into account when cosmological models are developed.

  11. Accurate age determinations of several nearby open clusters containing magnetic Ap stars

    CERN Document Server

    Silaj, J

    2014-01-01

    Aims: Our aim is to obtain ages that are as accurate as possible for the seven nearby open clusters alpha Per, Coma Ber, IC 2602, NGC 2232, NGC 2451A, NGC 2516, and NGC 6475, each of which contains at least one magnetic Ap or Bp star. Simultaneously, we test the current calibrations of Te and luminosity for the Ap/Bp star members, and identify clearly blue stragglers in the clusters studied. Methods: We explore the possibility that isochrone fitting in the theoretical Hertzsprung-Russell diagram (i.e. log (L/L&sun;) vs. log Te), rather than in the conventional colour-magnitude diagram, can provide more precise and accurate cluster ages, with well-defined uncertainties. Results: Well-defined ages are found for all the clusters studied. For the nearby clusters studied, the derived ages are not very sensitive to the small uncertainties in distance, reddening, membership, metallicity, or choice of isochrones. Our age determinations are all within the range of previously determined values, but the associated u...

  12. Rapid and accurate U-Th dating of ancient carbonates using inductively coupled plasma-quadrupole mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Douville, Eric; Salle, Eline; Frank, Norbert; Pons-Branchu, Edwige; Ayrault, Sophie [Laboratoire des Sciences du Climat et de l' Environnement, LSCE/IPSL, UMR 8212 CNRS-CEA-UVSQ, Domaine du CNRS, F-91198 Gif/Yvette (France); Eisele, Markus [MARUM, University of Bremen, Leobener Str., 28359 Bremen (DE)

    2010-07-01

    Here, the potential for rapid and accurate U-Th dating technique of marine aragonite skeletons (deep-sea corals, Lophelia pertusa) and secondary calcite deposits (speleothems and stalagmites) has been explored using inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). The analytical procedure includes a largely simplified chemical separation technique for uranium (U) and thorium (Th) using UTEVA resin. The developed technique permits simultaneous quantification of uranium [{sup 238}U] and thorium [{sup 232}Th] concentrations and their respective isotopic composition, required for U-series disequilibrium dating. Up to 50 U-Th dates per day can be achieved through ICP-QMS with {delta}{sup 234}U and {delta}{sup 230}Th reproducibility (2 {sigma}) of 3-4 parts per thousand and 1%, respectively. The high sensitivity ({>=}3.0 x 10{sup 5} cps/ppb) together with low background ({<=}0.5 cps) on each mass between 228 and 236 amu allowed U-Th dating of ancient deep-water corals (15-260 kyr) and stalagmites (30-85 kyr) at precision levels of less than 2%. Consequently, the combination of simplified chemistry using UTEVA with state-of-the-art ICP-QMS isotopic measurements that do not require a U-Th separation step now provides an extremely rapid and low-cost U-series dating technology. The level of precision is most convenient for numerous geochronological applications, such as the determination of climatic influences on ecosystem development and carbonate precipitation. As a first-example application we present ICP-QMS U-Th dates of North Atlantic deep-water coral fragments retrieved in the southeastern Porcupine Seabight (MD01-2463G. Mound Therese), indicating a purely interglacial growth of deep-water corals on so-called carbonate mounds over several climate cycles. (authors)

  13. Determination of the Linear Mass Power Spectrum From the Mass Function of Galaxy Clusters

    CERN Document Server

    Sánchez, A G; Lambas, D G

    2002-01-01

    We develop a new method to determine the linear mass power spectrum using the mass function of galaxy clusters. We obtain the rms mass fluctuation sigma (M) using the expression for the mass function in the Press & Schechter (1974), Sheth, Mo & Tormen (2001) and Jenkins et al. (2001) formalisms. We apply different techniques to recover the adimensional power spectrum Delta ^{2}(k) from sigma (M) namely the k_{eff} approximation, the singular value decomposition and the linear regularization method. The application of these techniques to the tCDM and LCDM GIF simulations shows a high efficiency in recovering the theoretical power spectrum over a wide range of scales. We compare our results with those derived from the power spectrum of the spatial distribution of the same sample of clusters in the simulations obtained by application of the classical Feldman, Kaiser & Peacock (1994), FKP, method. We find that the mass function based method presented here can provide a very accurate estimate of the li...

  14. Accurate Mass GC/LC-Quadrupole Time of Flight Mass Spectrometry Analysis of Fatty Acids and Triacylglycerols of Spicy Fruits from the Apiaceae Family.

    Science.gov (United States)

    Nguyen, Thao; Aparicio, Mario; Saleh, Mahmoud A

    2015-12-02

    The triacylglycerol (TAG) structure and the regio-stereospecific distribution of fatty acids (FA) of seed oils from most of the Apiaceae family are not well documented. The TAG structure ultimately determines the final physical properties of the oils and the position of FAs in the TAG molecule affects the digestion; absorption and metabolism; and physical and technological properties of TAGs. Fixed oils from the fruits of dill (Anethum graveolens), caraway (Carum carvi), cumin (Cuminum cyminum), coriander (Coriandrum sativum), anise (Pimpinella anisum), carrot (Daucus carota), celery (Apium graveolens), fennel (Foeniculum vulgare), and Khella (Ammi visnaga), all from the Apiaceae family, were extracted at room temperature in chloroform/methanol (2:1 v/v) using percolators. Crude lipids were fractionated by solid phase extraction to separate neutral triacylglycerols (TAGs) from other lipids components. Neutral TAGs were subjected to transesterification process to convert them to their corresponding fatty acids methyl esters (FAMES) using 1% boron trifluoride (BF₃) in methanol. FAMES were analyzed by gas chromatography-quadrupole time of flight (GC-QTOF) mass spectrometry. Triglycerides were analyzed using high performance liquid chromatography-quadrupole time of flight (LC-QTOF) mass spectrometry. Petroselinic acid was the major fatty acid in all samples ranging from 57% of the total fatty acids in caraway up to 82% in fennel. All samples contained palmitic (16:0), palmitoleic (C16:1n-9), stearic (C18:0), petroselinic (C18:1n-12), linoleic (C18:2n-6), linolinic (18:3n-3), and arachidic (C20:0) acids. TAG were analyzed using LC-QTOF for accurate mass identification and mass spectrometry/mass spectrometry (MS/MS) techniques for regiospesific elucidation of the identified TAGs. Five major TAGs were detected in all samples but with different relative concentrations in all of the tested samples. Several other TAGs were detected as minor components and were present in

  15. Accurate Mass GC/LC-Quadrupole Time of Flight Mass Spectrometry Analysis of Fatty Acids and Triacylglycerols of Spicy Fruits from the Apiaceae Family

    Science.gov (United States)

    Nguyen, Thao; Aparicio, Mario; Saleh, Mahmoud A.

    2016-01-01

    The triacylglycerol (TAG) structure and the regio-stereospecific distribution of fatty acids (FA) of seed oils from most of the Apiaceae family are not well documented. The TAG structure ultimately determines the final physical properties of the oils and the position of FAs in the TAG molecule affects the digestion; absorption and metabolism; and physical and technological properties of TAGs. Fixed oils from the fruits of dill (Anethum graveolens), caraway (Carum carvi), cumin (Cuminum cyminum), coriander (Coriandrum sativum), anise (Pimpinella anisum), carrot (Daucus carota), celery (Apium graveolens), fennel (Foeniculum vulgare), and Khella (Ammi visnaga), all from the Apiaceae family, were extracted at room temperature in chloroform/methanol (2:1 v/v) using percolators. Crude lipids were fractionated by solid phase extraction to separate neutral triacylglycerols (TAGs) from other lipids components. Neutral TAGs were subjected to transesterification process to convert them to their corresponding fatty acids methyl esters (FAMES) using 1% boron trifluoride (BF3) in methanol. FAMES were analyzed by gas chromatography-quadrupole time of flight (GC-QTOF) mass spectrometry. Triglycerides were analyzed using high performance liquid chromatography-quadrupole time of flight (LC-QTOF) mass spectrometry. Petroselinic acid was the major fatty acid in all samples ranging from 57% of the total fatty acids in caraway up to 82% in fennel. All samples contained palmitic (16:0), palmitoleic (C16:1n-9), stearic (C18:0), petroselinic (C18:1n-12), linoleic (C18:2n-6), linolinic (18:3n-3), and arachidic (C20:0) acids. TAG were analyzed using LC-QTOF for accurate mass identification and mass spectrometry/mass spectrometry (MS/MS) techniques for regiospesific elucidation of the identified TAGs. Five major TAGs were detected in all samples but with different relative concentrations in all of the tested samples. Several other TAGs were detected as minor components and were present in

  16. Accurate Mass GC/LC-Quadrupole Time of Flight Mass Spectrometry Analysis of Fatty Acids and Triacylglycerols of Spicy Fruits from the Apiaceae Family

    Directory of Open Access Journals (Sweden)

    Thao Nguyen

    2015-12-01

    Full Text Available The triacylglycerol (TAG structure and the regio-stereospecific distribution of fatty acids (FA of seed oils from most of the Apiaceae family are not well documented. The TAG structure ultimately determines the final physical properties of the oils and the position of FAs in the TAG molecule affects the digestion; absorption and metabolism; and physical and technological properties of TAGs. Fixed oils from the fruits of dill (Anethum graveolens, caraway (Carum carvi, cumin (Cuminum cyminum, coriander (Coriandrum sativum, anise (Pimpinella anisum, carrot (Daucus carota, celery (Apium graveolens, fennel (Foeniculum vulgare, and Khella (Ammi visnaga, all from the Apiaceae family, were extracted at room temperature in chloroform/methanol (2:1 v/v using percolators. Crude lipids were fractionated by solid phase extraction to separate neutral triacylglycerols (TAGs from other lipids components. Neutral TAGs were subjected to transesterification process to convert them to their corresponding fatty acids methyl esters (FAMES using 1% boron trifluoride (BF3 in methanol. FAMES were analyzed by gas chromatography-quadrupole time of flight (GC-QTOF mass spectrometry. Triglycerides were analyzed using high performance liquid chromatography-quadrupole time of flight (LC-QTOF mass spectrometry. Petroselinic acid was the major fatty acid in all samples ranging from 57% of the total fatty acids in caraway up to 82% in fennel. All samples contained palmitic (16:0, palmitoleic (C16:1n-9, stearic (C18:0, petroselinic (C18:1n-12, linoleic (C18:2n-6, linolinic (18:3n-3, and arachidic (C20:0 acids. TAG were analyzed using LC-QTOF for accurate mass identification and mass spectrometry/mass spectrometry (MS/MS techniques for regiospesific elucidation of the identified TAGs. Five major TAGs were detected in all samples but with different relative concentrations in all of the tested samples. Several other TAGs were detected as minor components and were present in some

  17. A fast and accurate method to compute the mass return from multiple stellar populations

    CERN Document Server

    Calura, F; Nipoti, C

    2013-01-01

    The mass returned to the ambient medium by aging stellar populations over cosmological times sums up to a significant fraction (20% - 30% or more) of their initial mass. This continuous mass injection plays a fundamental role in phenomena such as galaxy formation and evolution, fueling of supermassive black holes in galaxies and the consequent (negative and positive) feedback phenomena, and the origin of multiple stellar populations in globular clusters. In numerical simulations the calculation of the mass return can be time consuming, since it requires at each time step the evaluation of a convolution integral over the whole star formation history, so the computational time increases quadratically with the number of time-steps. The situation can be especially critical in hydrodynamical simulations, where different grid points are characterized by different star formation histories, and the gas cooling and heating times are shorter by orders of magnitude than the characteristic stellar lifetimes. In this pape...

  18. Directed Sample Interrogation Utilizing an Accurate Mass Exclusion-Based Data-Dependent Acquisition Strategy (AMEx)

    OpenAIRE

    Rudomin, Emily L.; Carr, Steven A.; Jaffe, Jacob D.

    2009-01-01

    The ability to perform thorough sampling is of critical importance when using mass spectrometry to characterize complex proteomic mixtures. A common approach is to re-interrogate a sample multiple times by LC-MS/MS. However, the conventional data-dependent acquisition methods that are typically used in proteomics studies will often redundantly sample high-intensity precursor ions while failing to sample low-intensity precursors entirely. We describe a method wherein the masses of successfully...

  19. High performance liquid chromatography method for rapid and accurate determination of homocysteine in plasma and serum

    DEFF Research Database (Denmark)

    Vester, Birte; Rasmussen, K

    1991-01-01

    Determination of homocysteine in plasma or serum for evaluation of cobalamin and folate deficiency is becoming an important diagnostic procedure. Accurate, rapid and low cost methods for measuring homocysteine are therefore required. We have improved an HPLC method and made it suitable for clinical...... application. The more important changes are the addition of an internal standard, mercaptopropionylglycine, and the use of a plasma/serum based calibration material. The method consists of the following steps: reduction of the sample with tri-n-butylphosphine, precipitation of proteins, derivatisation...... with ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate, and HPLC separation followed by fluorescence detection. The linearity of the assays is established and the coefficient of variation is 3.0%. Stability studies show that blood samples must be cooled or centrifuged immediately after venipuncture...

  20. Accurate determination of plasmid copy number of flow-sorted cells using droplet digital PCR.

    Science.gov (United States)

    Jahn, Michael; Vorpahl, Carsten; Türkowsky, Dominique; Lindmeyer, Martin; Bühler, Bruno; Harms, Hauke; Müller, Susann

    2014-06-17

    Many biotechnological processes rely on the expression of a plasmid-based target gene. A constant and sufficient number of plasmids per cell is desired for efficient protein production. To date, only a few methods for the determination of plasmid copy number (PCN) are available, and most of them average the PCN of total populations disregarding heterogeneous distributions. Here, we utilize the highly precise quantification of DNA molecules by droplet digital PCR (ddPCR) and combine it with cell sorting using flow cytometry. A duplex PCR assay was set up requiring only 1000 sorted cells for precise determination of PCN. The robustness of this method was proven by thorough optimization of cell sorting, cell disruption, and PCR conditions. When non plasmid-harboring cells of Pseudomonas putida KT2440 were spiked with different dilutions of the expression plasmid pA-EGFP_B, a PCN from 1 to 64 could be accurately detected. As a proof of principle, induced cultures of P. putida KT2440 producing an EGFP-fused model protein by means of the plasmid pA-EGFP_B were investigated by flow cytometry and showed two distinct subpopulations, fluorescent and nonfluorescent cells. These two subpopulations were sorted for PCN determination with ddPCR. A remarkably diverging plasmid distribution was found within the population, with nonfluorescent cells showing a much lower PCN (≤1) than fluorescent cells (PCN of up to 5) under standard conditions.

  1. Progress towards an accurate determination of the Boltzmann constant by Doppler spectroscopy

    CERN Document Server

    Lemarchand, Cyril; Darquié, Benoît; Bordé, Christian J; Chardonnet, Christian; Daussy, Christophe

    2010-01-01

    In this paper, we present significant progress performed on an experiment dedicated to the determination of the Boltzmann constant, k, by accurately measuring the Doppler absorption profile of a line in a gas of ammonia at thermal equilibrium. This optical method based on the first principles of statistical mechanics is an alternative to the acoustical method which has led to the unique determination of k published by the CODATA with a relative accuracy of 1.7 ppm. We report on the first measurement of the Boltzmann constant by laser spectroscopy with a statistical uncertainty below 10 ppm, more specifically 6.4 ppm. This progress results from improvements in the detection method and in the statistical treatment of the data. In addition, we have recorded the hyperfine structure of the probed saQ(6,3) rovibrational line of ammonia by saturation spectroscopy and thus determine very precisely the induced 4.36 (2) ppm broadening of the absorption linewidth. We also show that, in our well chosen experimental condi...

  2. Towards an accurate and precise determination of the solid-solid transition temperature of enantiotropic systems

    Energy Technology Data Exchange (ETDEWEB)

    Herman, Christelle, E-mail: christelle.herman@ulb.ac.b [Universite Libre de Bruxelles, Transfers, Interfaces and Processes Department, Chemical Engineering Unit, 50 Avenue Franklin D-Roosevelt, CP 165/67, 1050 Bruxelles (Belgium); Leyssens, Tom [Universite Catholique de Louvain, Institute of Condensed Matter and Nanosciences, 1 Place Louis Pasteur, 1348 Louvain-La-Neuve (Belgium); Vermylen, Valerie [UCB Pharma, 60 Allee de la Recherche, 1070 Braine l' Alleud (Belgium); Halloin, Veronique; Haut, Benoit [Universite Libre de Bruxelles, Transfers, Interfaces and Processes Department, Chemical Engineering Unit, 50 Avenue Franklin D-Roosevelt, CP 165/67, 1050 Bruxelles (Belgium)

    2011-05-15

    the second experimental method is a more accurate, precise, time- and effort-friendly method for the determination of T{sub tr}. The solid-solid transition temperature of the Etiracetam system, determined with the second method, using three different solvents, is found to be equal to 303.65 K {+-} 0.5 K.

  3. Fuzzy Reasoning to More Accurately Determine Void Areas on Optical Micrographs of Composite Structures

    Science.gov (United States)

    Dominquez, Jesus A.; Tate, Lanetra C.; Wright, M. Clara; Caraccio, Anne

    2013-01-01

    Accomplishing the best-performing composite matrix (resin) requires that not only the processing method but also the cure cycle generate low-void-content structures. If voids are present, the performance of the composite matrix will be significantly reduced. This is usually noticed by significant reductions in matrix-dominated properties, such as compression and shear strength. Voids in composite materials are areas that are absent of the composite components: matrix and fibers. The characteristics of the voids and their accurate estimation are critical to determine for high performance composite structures. One widely used method of performing void analysis on a composite structure sample is acquiring optical micrographs or Scanning Electron Microscope (SEM) images of lateral sides of the sample and retrieving the void areas within the micrographs/images using an image analysis technique. Segmentation for the retrieval and subsequent computation of void areas within the micrographs/images is challenging as the gray-scaled values of the void areas are close to the gray-scaled values of the matrix leading to the need of manually performing the segmentation based on the histogram of the micrographs/images to retrieve the void areas. The use of an algorithm developed by NASA and based on Fuzzy Reasoning (FR) proved to overcome the difficulty of suitably differentiate void and matrix image areas with similar gray-scaled values leading not only to a more accurate estimation of void areas on composite matrix micrographs but also to a faster void analysis process as the algorithm is fully autonomous.

  4. Fuzzy Reasoning to More Accurately Determine Void Areas on Optical Micrographs of Composite Structures

    Science.gov (United States)

    Dominguez, Jesus A.; Tate, Lanetra C.; Wright, M. Clara; Caraccio, Anne

    2013-12-01

    Accomplishing the best-performing composite matrix (resin) requires that not only the processing method but also the cure cycle generate low-void-content structures. If voids are present, the performance of the composite matrix will be significantly reduced. This is usually noticed by significant reductions in matrix-dominated properties, such as compression and shear strength. Voids in composite materials are areas that are absent of the composite components: matrix and fibers. The characteristics of the voids and their accurate estimation are critical to determine for high performance composite structures. One widely used method of performing void analysis on a composite structure sample is acquiring optical micrographs or Scanning Electron Microscope (SEM) images of lateral sides of the sample and retrieving the void areas within the micrographs/images using an image analysis technique. Segmentation for the retrieval and subsequent computation of void areas within the micrographs/images is challenging as the gray-scaled values of the void areas are close to the gray-scaled values of the matrix leading to the need of manually performing the segmentation based on the histogram of the micrographs/images to retrieve the void areas. The use of an algorithm developed by NASA and based on Fuzzy Reasoning (FR) proved to overcome the difficulty of suitably differentiate void and matrix image areas with similar gray-scaled values leading not only to a more accurate estimation of void areas on composite matrix micrographs but also to a faster void analysis process as the algorithm is fully autonomous.

  5. 45 CFR 261.64 - How will we determine whether a State's work verification procedures ensure an accurate work...

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 2 2010-10-01 2010-10-01 false How will we determine whether a State's work verification procedures ensure an accurate work participation measurement? 261.64 Section 261.64 Public Welfare... work verification procedures ensure an accurate work participation measurement? (a) We will...

  6. Precision cluster mass determination from weak lensing

    CERN Document Server

    Mandelbaum, Rachel; Baldauf, Tobias; Smith, Robert E

    2009-01-01

    Weak gravitational lensing has been used extensively in the past decade to constrain the masses of galaxy clusters, and is the most promising observational technique for providing the mass calibration necessary for precision cosmology with clusters. There are several challenges in estimating cluster masses, particularly (a) the sensitivity to astrophysical effects and observational systematics that modify the signal relative to the theoretical expectations, and (b) biases that can arise due to assumptions in the mass estimation method, such as the assumed radial profile of the cluster. All of these challenges are more problematic in the inner regions of the cluster, suggesting that their influence would ideally be suppressed for the purpose of mass estimation. However, at any given radius the differential surface density measured by lensing is sensitive to all mass within that radius, and the corrupted signal from the inner parts is spread out to all scales. We develop a new statistic that is ideal for estima...

  7. Accurate mass measurements of $^{26}$Ne, $^{26-30}$Na, $^{29-33}$Mg performed with the MISTRAL spectrometer

    CERN Document Server

    Gaulard, C; Bachelet, C; De Simon, M S; Lunney, M D; Thibault, C; Vieira, N

    2006-01-01

    The minuteness of the nuclear binding energy requires that mass measurements be highly precise and accurate. Here we report on new measurements $^{29-33}$Mg and $^{26}$Na performed with the Mistral mass spectrometer at CERN's Isolde facility. Since mass measurements are prone to systematic errors, considerable effort has been devoted to their evaluation and elimination in order to achieve accuracy and not only precision. We have therefore conducted a campaign of measurements for calibration and error evaluation. As a result, we now have a satisfactory description of the Mistral calibration laws and error budget. We have applied our new understanding to previous measurements of $^{26}$Ne, $^{26-30}$Na and $^{29,32}$Mg for which re-evaluated values are reported.

  8. Accurate and precise determination of critical properties from Gibbs ensemble Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Dinpajooh, Mohammadhasan [Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455 (United States); Bai, Peng; Allan, Douglas A. [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455 (United States); Siepmann, J. Ilja, E-mail: siepmann@umn.edu [Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455 (United States); Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455 (United States)

    2015-09-21

    Since the seminal paper by Panagiotopoulos [Mol. Phys. 61, 813 (1997)], the Gibbs ensemble Monte Carlo (GEMC) method has been the most popular particle-based simulation approach for the computation of vapor–liquid phase equilibria. However, the validity of GEMC simulations in the near-critical region has been questioned because rigorous finite-size scaling approaches cannot be applied to simulations with fluctuating volume. Valleau [Mol. Simul. 29, 627 (2003)] has argued that GEMC simulations would lead to a spurious overestimation of the critical temperature. More recently, Patel et al. [J. Chem. Phys. 134, 024101 (2011)] opined that the use of analytical tail corrections would be problematic in the near-critical region. To address these issues, we perform extensive GEMC simulations for Lennard-Jones particles in the near-critical region varying the system size, the overall system density, and the cutoff distance. For a system with N = 5500 particles, potential truncation at 8σ and analytical tail corrections, an extrapolation of GEMC simulation data at temperatures in the range from 1.27 to 1.305 yields T{sub c} = 1.3128 ± 0.0016, ρ{sub c} = 0.316 ± 0.004, and p{sub c} = 0.1274 ± 0.0013 in excellent agreement with the thermodynamic limit determined by Potoff and Panagiotopoulos [J. Chem. Phys. 109, 10914 (1998)] using grand canonical Monte Carlo simulations and finite-size scaling. Critical properties estimated using GEMC simulations with different overall system densities (0.296 ≤ ρ{sub t} ≤ 0.336) agree to within the statistical uncertainties. For simulations with tail corrections, data obtained using r{sub cut} = 3.5σ yield T{sub c} and p{sub c} that are higher by 0.2% and 1.4% than simulations with r{sub cut} = 5 and 8σ but still with overlapping 95% confidence intervals. In contrast, GEMC simulations with a truncated and shifted potential show that r{sub cut} = 8σ is insufficient to obtain accurate results. Additional GEMC simulations for hard

  9. Accurate mass analysis of ethanesulfonic acid degradates of acetochlor and alachlor using high-performance liquid chromatography and time-of-flight mass spectrometry

    Science.gov (United States)

    Thurman, E.M.; Ferrer, I.; Parry, R.

    2002-01-01

    Degradates of acetochlor and alachlor (ethanesulfonic acids, ESAs) were analyzed in both standards and in a groundwater sample using high-performance liquid chromatography-time-of-flight mass spectrometry with electrospray ionization. The negative pseudomolecular ion of the secondary amide of acetochlor ESA and alachlor ESA gave average masses of 256.0750??0.0049 amu and 270.0786??0.0064 amu respectively. Acetochlor and alachlor ESA gave similar masses of 314.1098??0.0061 amu and 314.1153??0.0048 amu; however, they could not be distinguished by accurate mass because they have the same empirical formula. On the other hand, they may be distinguished using positive-ion electrospray because of different fragmentation spectra, which did not occur using negative-ion electrospray.

  10. Accurate proteome-wide protein quantification from high-resolution 15N mass spectra.

    Science.gov (United States)

    Khan, Zia; Amini, Sasan; Bloom, Joshua S; Ruse, Cristian; Caudy, Amy A; Kruglyak, Leonid; Singh, Mona; Perlman, David H; Tavazoie, Saeed

    2011-12-19

    In quantitative mass spectrometry-based proteomics, the metabolic incorporation of a single source of 15N-labeled nitrogen has many advantages over using stable isotope-labeled amino acids. However, the lack of a robust computational framework for analyzing the resulting spectra has impeded wide use of this approach. We have addressed this challenge by introducing a new computational methodology for analyzing 15N spectra in which quantification is integrated with identification. Application of this method to an Escherichia coli growth transition reveals significant improvement in quantification accuracy over previous methods.

  11. Accurate mass measurements of short-lived isotopes with the MISTRAL rf spectrometer

    CERN Document Server

    Toader, C F; Borcea, C; Doubre, H; Duma, M; Jacotin, M; Henry, S; Képinski, J F; Lebée, G; Le Scornet, G; Lunney, M D; Monsanglant, C; De Saint-Simon, M; Thibault, C

    1999-01-01

    The MISTRAL experiment has measured its first masses at ISOLDE. Installed in May 1997, this radiofrequency transmission spectrometer is to concentrate on nuclides with particularly short half-lives. MISTRAL received its first stable beam in October and first radioactive beam in November 1997. These first tests, with a plasma ion source, resulted in excellent isobaric separation and reasonable transmission. Further testing and development enabled first data taking in July 1998 on neutron-rich Na isotopes having half-lives as short as 31 ms.

  12. Dynamic Bayesian Network for Accurate Detection of Peptides from Tandem Mass Spectra.

    Science.gov (United States)

    Halloran, John T; Bilmes, Jeff A; Noble, William S

    2016-08-05

    A central problem in mass spectrometry analysis involves identifying, for each observed tandem mass spectrum, the corresponding generating peptide. We present a dynamic Bayesian network (DBN) toolkit that addresses this problem by using a machine learning approach. At the heart of this toolkit is a DBN for Rapid Identification (DRIP), which can be trained from collections of high-confidence peptide-spectrum matches (PSMs). DRIP's score function considers fragment ion matches using Gaussians rather than fixed fragment-ion tolerances and also finds the optimal alignment between the theoretical and observed spectrum by considering all possible alignments, up to a threshold that is controlled using a beam-pruning algorithm. This function not only yields state-of-the art database search accuracy but also can be used to generate features that significantly boost the performance of the Percolator postprocessor. The DRIP software is built upon a general purpose DBN toolkit (GMTK), thereby allowing a wide variety of options for user-specific inference tasks as well as facilitating easy modifications to the DRIP model in future work. DRIP is implemented in Python and C++ and is available under Apache license at http://melodi-lab.github.io/dripToolkit .

  13. Stellar mass-to-light ratios from galaxy spectra: how accurate can they be?

    CERN Document Server

    Gallazzi, Anna

    2009-01-01

    Stellar masses play a crucial role in the exploration of galaxy properties and the evolution of the galaxy population. In this paper, we explore the minimum possible uncertainties in stellar mass-to-light (M/L) ratios from the assumed star formation history (SFH) and metallicity distribution, with the goals of providing a minimum set of requirements for observational studies. We use a large Monte Carlo library of SFHs to study as a function of galaxy spectral type and signal-to-noise ratio (S/N) the statistical uncertainties of M/L values using either absorption-line data or broad band colors. The accuracy of M/L estimates can be significantly improved by using metal-sensitive indices in combination with age-sensitive indices, in particular for galaxies with intermediate-age or young stellar populations. While M/L accuracy clearly depends on the spectral S/N ratio, there is no significant gain in improving the S/N much above 50/pix and limiting uncertainties of 0.03 dex are reached. Assuming that dust is accu...

  14. Significance of accurate diffraction corrections for the second harmonic wave in determining the acoustic nonlinearity parameter

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hyunjo, E-mail: hjjeong@wku.ac.kr [Division of Mechanical and Automotive Engineering, Wonkwang University, Iksan, Jeonbuk 570-749 (Korea, Republic of); Zhang, Shuzeng; Li, Xiongbing [School of Traffic and Transportation Engineering, Central South University, Changsha, Hunan 410075 (China); Barnard, Dan [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50010 (United States)

    2015-09-15

    The accurate measurement of acoustic nonlinearity parameter β for fluids or solids generally requires making corrections for diffraction effects due to finite size geometry of transmitter and receiver. These effects are well known in linear acoustics, while those for second harmonic waves have not been well addressed and therefore not properly considered in previous studies. In this work, we explicitly define the attenuation and diffraction corrections using the multi-Gaussian beam (MGB) equations which were developed from the quasilinear solutions of the KZK equation. The effects of making these corrections are examined through the simulation of β determination in water. Diffraction corrections are found to have more significant effects than attenuation corrections, and the β values of water can be estimated experimentally with less than 5% errors when the exact second harmonic diffraction corrections are used together with the negligible attenuation correction effects on the basis of linear frequency dependence between attenuation coefficients, α{sub 2} ≃ 2α{sub 1}.

  15. Accurate determination of minority carrier mobility in silicon from quasi-steady-state photoluminescence

    Science.gov (United States)

    Giesecke, J. A.; Schindler, F.; Bühler, M.; Schubert, M. C.; Warta, W.

    2013-06-01

    Minority carrier mobility is a crucial transport property affecting the performance of semiconductor devices such as solar cells. Compensation of dopant species and novel multicrystalline materials call for accurate knowledge of minority carrier mobility for device simulation and characterization. Yet, measurement techniques of minority carrier mobility are scarce, and published data scatter significantly even on monocrystalline material. In this paper, the determination of minority carrier mobility from self-consistent quasi-steady-state photoluminescence measurements of effective carrier lifetime is presented. The measurement design is distinguished by a limitation of carrier recombination through minority carrier transport—with excess carrier generation and recombination confined to opposite interfaces, respectively. Minority carrier mobility is inferred from the minority carrier diffusion coefficient via the Einstein relation. An experimental proof of concept on monocrystalline p-type material is provided, showing good agreement with state-of-the-art data and models. Considerations for the applicability of the method to compensated and multicrystalline silicon materials are discussed.

  16. Diagnostic methodology is critical for accurately determining the prevalence of ichthyophonus infections in wild fish populations

    Science.gov (United States)

    Kocan, R.; Dolan, H.; Hershberger, P.

    2011-01-01

    Several different techniques have been employed to detect and identify Ichthyophonus spp. in infected fish hosts; these include macroscopic observation, microscopic examination of tissue squashes, histological evaluation, in vitro culture, and molecular techniques. Examination of the peer-reviewed literature revealed that when more than 1 diagnostic method is used, they often result in significantly different results; for example, when in vitro culture was used to identify infected trout in an experimentally exposed population, 98.7% of infected trout were detected, but when standard histology was used to confirm known infected tissues from wild salmon, it detected ~50% of low-intensity infections and ~85% of high-intensity infections. Other studies on different species reported similar differences. When we examined a possible mechanism to explain the disparity between different diagnostic techniques, we observed non-random distribution of the parasite in 3-dimensionally visualized tissue sections from infected hosts, thus providing a possible explanation for the different sensitivities of commonly used diagnostic techniques. Based on experimental evidence and a review of the peer-reviewed literature, we have concluded that in vitro culture is currently the most accurate diagnostic technique for determining infection prevalence of Ichthyophonus, particularly when the exposure history of the population is not known.

  17. A miniature shoe-mounted orientation determination system for accurate indoor heading and trajectory tracking

    Science.gov (United States)

    Zhang, Shengzhi; Yu, Shuai; Liu, Chaojun; Liu, Sheng

    2016-06-01

    Tracking the position of pedestrian is urgently demanded when the most commonly used GPS (Global Position System) is unavailable. Benefited from the small size, low-power consumption, and relatively high reliability, micro-electro-mechanical system sensors are well suited for GPS-denied indoor pedestrian heading estimation. In this paper, a real-time miniature orientation determination system (MODS) was developed for indoor heading and trajectory tracking based on a novel dual-linear Kalman filter. The proposed filter precludes the impact of geomagnetic distortions on pitch and roll that the heading is subjected to. A robust calibration approach was designed to improve the accuracy of sensors measurements based on a unified sensor model. Online tests were performed on the MODS with an improved turntable. The results demonstrate that the average RMSE (root-mean-square error) of heading estimation is less than 1°. Indoor heading experiments were carried out with the MODS mounted on the shoe of pedestrian. Besides, we integrated the existing MODS into an indoor pedestrian dead reckoning application as an example of its utility in realistic actions. A human attitude-based walking model was developed to calculate the walking distance. Test results indicate that mean percentage error of indoor trajectory tracking achieves 2% of the total walking distance. This paper provides a feasible alternative for accurate indoor heading and trajectory tracking.

  18. Rapid, accurate, and direct determination of total lycopene content in tomato paste

    Science.gov (United States)

    Bicanic, D.; Anese, M.; Luterotti, S.; Dadarlat, D.; Gibkes, J.; Lubbers, M.

    2003-01-01

    Lycopene that imparts red color to the tomato fruit is the most potent antioxidant among carotenes, an important nutrient and also used as a color ingredient in many food formulations. Since cooked and processed foods derived from tomatoes were shown to provide optimal lycopene boost, products such as paste, puree, juice, etc. are nowadays gaining popularity as dietary sources. The analysis of lycopene in tomato paste (partially dehydrated product prepared by vacuum concentrating tomato juice) is carried out using either high pressure liquid chromatography (HPLC), spectrophotometry, or by evaluating the color. The instability of lycopene during processes of extraction, etc., handling, and disposal of organic solvents makes the preparation of a sample for the analysis a delicate task. Despite a recognized need for accurate and rapid assessment of lycopene in tomato products no such method is available at present. The study described here focuses on a direct determination of a total lycopene content in different tomato pastes by means of the laser optothermal window (LOW) method at 502 nm. The concentration of lycopene in tomato paste ranged between 25 and 150 mg per 100 g product; the results are in excellent agreement with those obtained by spectrophotometry. The time needed to complete LOW analysis is very short, so that decomposition of pigment and the formation of artifacts are minimized. Preliminary results indicate a good degree of reproducibility making the LOW method suitable for routine assays of lycopene content in tomato paste.

  19. A versatile assay for the accurate, time-resolved determination of cellular viability.

    Science.gov (United States)

    Amano, Toyoki; Hirasawa, Ken ichi; O'Donohue, Michael J; Pernolle, Jean Claude; Shioi, Yuzo

    2003-03-01

    A convenient and versatile method for the accurate, time-resolved determination of cellular viability has been developed. The conventional viability indicator fluorescein diacetate (FDA), which is converted to the fluorescent compound fluorescein in living cells, was employed as a viability probe. Fluorescence emission from cells was measured using a spectrofluorimeter equipped with a magnetic stirrer. Using this assay cell suspensions exhibiting densities in the range 0.5 x 10(5) to 2.0 x 10(5) cells displayed a linear response when FDA concentrations less than 12 micro M were employed. To calibrate the method, viability standards were elaborated using different proportions of living and dead cells, and a correlation coefficient for the viability of tobacco BY-2 suspensions was calculated as 0.998. This viability assay was also found to be applicable to Chlamydomonas reinhardtii and Arabidopsis thaliana cultured cells. Using this cell viability assay, kinetic analyses of cell death could be performed. Using the proteinaceous elicitor from Phytophthora cryptogea, cryptogein, to induce cell death in tobacco cell suspensions, values for the maximum velocity of death induction rate (V(max)) and the LD50 (half-maximal velocity or k(1/2)) were calculated as 17.2 (% death/h) and 65 nM, respectively.

  20. New determination of the electron's mass.

    Science.gov (United States)

    Beier, Thomas; Häffner, Hartmut; Hermanspahn, Nikolaus; Karshenboim, Savely G; Kluge, H-Jürgen; Quint, Wolfgang; Stahl, Stefan; Verdú, José; Werth, Günther

    2002-01-07

    A new independent value for the electron's mass in units of the atomic mass unit is presented, m(e) = 0.000 548 579 909 2(4) u. The value is obtained from our recent measurement of the g factor of the electron in (12)C(5+) in combination with the most recent quantum electrodynamical (QED) predictions. In the QED corrections, terms of order alpha(2) were included by a perturbation expansion in Zalpha. Our total precision is three times better than that of the accepted value for the electron's mass.

  1. Highly accurate chemical formula prediction tool utilizing high-resolution mass spectra, MS/MS fragmentation, heuristic rules, and isotope pattern matching.

    Science.gov (United States)

    Pluskal, Tomáš; Uehara, Taisuke; Yanagida, Mitsuhiro

    2012-05-15

    Mass spectrometry is commonly applied to qualitatively and quantitatively profile small molecules, such as peptides, metabolites, or lipids. Modern mass spectrometers provide accurate measurements of mass-to-charge ratios of ions, with errors as low as 1 ppm. Even such high mass accuracy, however, is not sufficient to determine the unique chemical formula of each ion, and additional algorithms are necessary. Here we present a universal software tool for predicting chemical formulas from high-resolution mass spectrometry data, developed within the MZmine 2 framework. The tool is based on the use of a combination of heuristic techniques, including MS/MS fragmentation analysis and isotope pattern matching. The performance of the tool was evaluated using a real metabolomic data set obtained with the Orbitrap MS detector. The true formula was correctly determined as the highest-ranking candidate for 79% of the tested compounds. The novel isotope pattern-scoring algorithm outperformed a previously published method in 64% of the tested Orbitrap spectra. The software described in this manuscript is freely available and its source code can be accessed within the MZmine 2 source code repository.

  2. Accurate nuclear masses from a three parameter Kohn-Sham DFT approach (BCPM)

    CERN Document Server

    Baldo, M; Schuck, P; Viñas, X

    2012-01-01

    Given the promising features of the recently proposed Barcelona-Catania-Paris (BCP) functional \\cite{Baldo.08}, it is the purpose of this paper to still improve on it. It is, for instance, shown that the number of open parameters can be reduced from 4-5 to 2-3, i.e. by practically a factor of two. One parameter is tightly fixed by a fine-tuning of the bulk, a second by the surface energy. The third is the strength of the spin-orbit potential on which the final result does not depend within the scatter of the values used in Skyrme and Gogny like functionals. An energy rms value of 1.58 MeV is obtained from a fit of these three parameters to the 579 measured masses reported in the Audi and Waspra 2003 compilation. This rms value compares favorably with the one obtained using other successful mean field theories. Charge radii are also well reproduced when compared with experiment. The energies of some excited states, mostly the isoscalar giant monopole resonances, are studied within this model as well.

  3. Precision Determination of the Top Quark Mass

    Energy Technology Data Exchange (ETDEWEB)

    Movilla Fernandez, Pedro A.; /LBL, Berkeley

    2007-05-01

    The CDF and D0 collaborations have updated their measurements of the mass of the top quark using proton-antiproton collisions at {radical}s = 1.96 TeV produced at the Tevatron. The uncertainties in each of the top-antitop decay channels have been reduced. The new Tevatron average for the mass of the top quark based on about 1 fb{sup -1} of data per experiment is 170.9 {+-} 1.8 GeV/c{sup 2}.

  4. Accurate modeling of intermediate-mass-ratio inspirals: exploring the form of the self-force in the intermediate-mass-ratio regime

    CERN Document Server

    Huerta, E A; Brown, Duncan A

    2012-01-01

    The LIGO detector is undergoing a major upgrade that will increase its sensitivity by a factor of 10, and extend its bandwidth from 40 Hz to 10 Hz on the lower frequency end, while also allowing for high-frequency operation due to its tunability. This advanced LIGO (aLIGO) detector will extend the mass range at which compact mass binaries may be detected by a factor of four or more at a fixed signal-to-noise ratio [1]. The inspirals of stellar-mass compact objects into intermediate-mass black holes (IMBHs) of 50-350 solar masses will lie in the frequency band of aLIGO [2]. GW searches for these type of events will provide conclusive evidence for the existence of IMBHs and explore the dynamics of cluster environments. To realize this science we need to develop waveform templates that accurately capture the dynamical evolution of these type of events before aLIGO begins observations. Implementing gravitational self-force (SF) corrections in templates for compact binaries with mass-ratios 1:10-1:1000 will be ess...

  5. Fourier Transform Mass Spectrometry and Nuclear Magnetic Resonance Analysis for the Rapid and Accurate Characterization of Hexacosanoylceramide

    Directory of Open Access Journals (Sweden)

    Charles W. Ross

    2016-06-01

    Full Text Available Ceramides are a central unit of all sphingolipids which have been identified as sites of biological recognition on cellular membranes mediating cell growth and differentiation. Several glycosphingolipids have been isolated, displaying immunomodulatory and anti-tumor activities. These molecules have generated considerable interest as potential vaccine adjuvants in humans. Accurate analyses of these and related sphingosine analogues are important for the characterization of structure, biological function, and metabolism. We report the complementary use of direct laser desorption ionization (DLDI, sheath flow electrospray ionization (ESI Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS and high-field nuclear magnetic resonance (NMR analysis for the rapid, accurate identification of hexacosanoylceramide and starting materials. DLDI does not require stringent sample preparation and yields representative ions. Sheath-flow ESI yields ions of the product and byproducts and was significantly better than monospray ESI due to improved compound solubility. Negative ion sheath flow ESI provided data of starting materials and products all in one acquisition as hexacosanoic acid does not ionize efficiently when ceramides are present. NMR provided characterization of these lipid molecules complementing the results obtained from MS analyses. NMR data was able to differentiate straight chain versus branched chain alkyl groups not easily obtained from mass spectrometry.

  6. Fourier Transform Mass Spectrometry and Nuclear Magnetic Resonance Analysis for the Rapid and Accurate Characterization of Hexacosanoylceramide.

    Science.gov (United States)

    Ross, Charles W; Simonsick, William J; Bogusky, Michael J; Celikay, Recep W; Guare, James P; Newton, Randall C

    2016-06-28

    Ceramides are a central unit of all sphingolipids which have been identified as sites of biological recognition on cellular membranes mediating cell growth and differentiation. Several glycosphingolipids have been isolated, displaying immunomodulatory and anti-tumor activities. These molecules have generated considerable interest as potential vaccine adjuvants in humans. Accurate analyses of these and related sphingosine analogues are important for the characterization of structure, biological function, and metabolism. We report the complementary use of direct laser desorption ionization (DLDI), sheath flow electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) and high-field nuclear magnetic resonance (NMR) analysis for the rapid, accurate identification of hexacosanoylceramide and starting materials. DLDI does not require stringent sample preparation and yields representative ions. Sheath-flow ESI yields ions of the product and byproducts and was significantly better than monospray ESI due to improved compound solubility. Negative ion sheath flow ESI provided data of starting materials and products all in one acquisition as hexacosanoic acid does not ionize efficiently when ceramides are present. NMR provided characterization of these lipid molecules complementing the results obtained from MS analyses. NMR data was able to differentiate straight chain versus branched chain alkyl groups not easily obtained from mass spectrometry.

  7. A new tool to determine masses and mass profiles using gravitational flexion

    CERN Document Server

    Leonard, Adrienne

    2009-01-01

    In a recent publication, an aperture mass statistic for gravitational flexion was derived and shown to be effective, at least with simulated data, in detecting massive structures and substructures within clusters of galaxies. Further, it was suggested that the radius at which the flexion aperture mass signal falls to zero might allow for estimation of the mass or density profile of the structures detected. In this paper, we more fully explore this possibility, considering the behaviour both of the peak signal and the zero-signal contours for two mass models--the singular isothermal sphere and Navarro-Frenk-White profiles--under varying aperture size, filter shape and mass concentration parameter. We demonstrate the effectiveness of the flexion aperture mass statistic in discriminating between mass profiles and concentration parameters, and in providing an accurate estimate of the mass of the lens, to within a factor of 2 or better.

  8. An accurate method for microanalysis of carbon monoxide in putrid postmortem blood by head-space gas chromatography-mass spectrometry (HS/GC/MS).

    Science.gov (United States)

    Hao, Hongxia; Zhou, Hong; Liu, Xiaopei; Zhang, Zhong; Yu, Zhongshan

    2013-06-10

    Carbon monoxide (CO) may be the cause of more than half the fatal poisonings reported in many countries, with some of these cases under-reported or misdiagnosed by medical professionals. Therefore, an accurate and reliable analytical method to measure blood carboxyhemoglobin level (COHb%), in the 1% to lethal range, is essential for correct diagnosis. Herein a method was established, i.e. head-space gas chromatography-mass spectrometry (HS/GC/MS) that has numerous advantages over other techniques, such as UV spectrometry, for determination of COHb%. There was a linear relationship (R(2)=0. 9995) between the peak area for CO and the COHb% in blood. Using a molecular sieve-packed column, CO levels in the air down to 0.01% and COHb% levels in small blood samples down to 0.2% could be quantitated rapidly and accurately. Furthermore, this method showed good reproducibility with a relative standard deviation for COHb% of <1%. Therefore, this technique provides an accurate and reliable method for determining CO and COHb% levels and may prove useful for investigation of deaths potentially related to CO exposure.

  9. Search for new candidates for the neutrino-oriented mass determination by electron-capture

    CERN Multimedia

    Herfurth, F; Boehm, C; Blaum, K; Beck, D

    2008-01-01

    This proposal is part of an extended program dedicated to the neutrino-mass determination in the electron-capture sector, which aims at ultra-precise mass measurements by Penning traps in combination with cryogenic micro-calorimetry for atomic de-excitation measurements. Here, precise mass measurements with ISOLTRAP are proposed for the orbital electron-capture nuclides $^{194}$Hg and $^{202}$Pb, as well as their daughters, with the goal to determine accurately their Q-values. These values are expected to be the smallest ones among a great variety of known electron-capture precursors. Therefore, these nuclides are strong candidates for an improved electron-neutrino mass determination. We ask for 8 shifts of on-line beam at ISOLDE for mass measurements of $^{194}$Hg, $^{194}$ Au, $^{202}$Pb, and $^{202}$Tl at ISOLTRAP.

  10. Isotopic Ratio Outlier Analysis of the S. cerevisiae Metabolome Using Accurate Mass Gas Chromatography/Time-of-Flight Mass Spectrometry: A New Method for Discovery.

    Science.gov (United States)

    Qiu, Yunping; Moir, Robyn; Willis, Ian; Beecher, Chris; Tsai, Yu-Hsuan; Garrett, Timothy J; Yost, Richard A; Kurland, Irwin J

    2016-03-01

    Isotopic ratio outlier analysis (IROA) is a (13)C metabolomics profiling method that eliminates sample to sample variance, discriminates against noise and artifacts, and improves identification of compounds, previously done with accurate mass liquid chromatography/mass spectrometry (LC/MS). This is the first report using IROA technology in combination with accurate mass gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS), here used to examine the S. cerevisiae metabolome. S. cerevisiae was grown in YNB media, containing randomized 95% (13)C, or 5%(13)C glucose as the single carbon source, in order that the isotopomer pattern of all metabolites would mirror the labeled glucose. When these IROA experiments are combined, the abundance of the heavy isotopologues in the 5%(13)C extracts, or light isotopologues in the 95%(13)C extracts, follows the binomial distribution, showing mirrored peak pairs for the molecular ion. The mass difference between the (12)C monoisotopic and the (13)C monoisotopic equals the number of carbons in the molecules. The IROA-GC/MS protocol developed, using both chemical and electron ionization, extends the information acquired from the isotopic peak patterns for formulas generation. The process that can be formulated as an algorithm, in which the number of carbons, as well as the number of methoximations and silylations are used as search constraints. In electron impact (EI/IROA) spectra, the artifactual peaks are identified and easily removed, which has the potential to generate "clean" EI libraries. The combination of chemical ionization (CI) IROA and EI/IROA affords a metabolite identification procedure that enables the identification of coeluting metabolites, and allowed us to characterize 126 metabolites in the current study.

  11. Accurate determination of ultra-trace levels of Ti in blood serum using ICP-MS/MS

    Energy Technology Data Exchange (ETDEWEB)

    Balcaen, Lieve, E-mail: Lieve.Balcaen@UGent.be [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, B-9000 Ghent (Belgium); Bolea-Fernandez, Eduardo, E-mail: Eduardo.BoleaFernandez@UGent.be [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, B-9000 Ghent (Belgium); Resano, Martín, E-mail: mresano@unizar.es [University of Zaragoza, Department of Analytical Chemistry, Pedro Cerbuna 12, E-50009 Zaragoza (Spain); Vanhaecke, Frank, E-mail: Frank.Vanhaecke@UGent.be [Ghent University, Department of Analytical Chemistry, Krijgslaan 281-S12, B-9000 Ghent (Belgium)

    2014-01-27

    Graphical abstract: -- Highlights: •Novel method for determination of Ti at ultra-trace levels in clinical samples (serum). •Novel method based on Ti(NH{sub 3}){sub 6}{sup +} reaction product ion formation and double mass selection using recently introduced ICP-QQQ instrumentation. •Lowest limits of detection ever obtained using quadrupole-based instrumentation for Ti. •Accurate determination of basal levels of Ti in blood serum. -- Abstract: Ti is frequently used in implants and prostheses and it has been shown before that the presence of these in the human body can lead to elevated Ti concentrations in body fluids such as serum and urine. As identification of the exact mechanisms responsible for this increase in Ti concentrations, and the risks associated with it, are not fully understood, it is important to have sound analytical methods that enable straightforward quantification of Ti levels in body fluids (for both implanted and non-implanted individuals). Until now, only double-focusing sector field ICP-mass spectrometry (SF-ICP-MS) offered limits of detection that are good enough to deal with the very low basal levels of Ti in human serum. This work reports on the development of a novel method for the accurate and precise determination of trace levels of Ti in human serum samples, based on the use of ICP-MS/MS. O{sub 2} and NH{sub 3}/He have been compared as reaction gases. While the use of O{sub 2} did not enable to overcome all spectral interferences, it has been shown that conversion of Ti{sup +} ions into Ti(NH{sub 3}){sub 6}{sup +} cluster ions by using NH{sub 3}/He as a reaction gas in an ICP-QQQ-MS system, operated in MS/MS mode, provided interference-free conditions and sufficiently low limits of detection, down to 3 ng L{sup −1} (instrumental detection limit obtained for the most abundant Ti isotope). The accuracy of the method proposed was evaluated by analysis of a Seronorm Trace Elements Serum L-1 reference material and by comparing the

  12. Improved manometric setup for the accurate determination of supercritical carbon dioxide sorption

    NARCIS (Netherlands)

    Van Hemert, P.; Bruining, H.; Rudolph, E.S.J.; Wolf, K.H.A.A.; Maas, J.G.

    2009-01-01

    An improved version of the manometric apparatus and its procedures for measuring excess sorption of supercritical carbon dioxide are presented in detail with a comprehensive error analysis. An improved manometric apparatus is necessary for accurate excess sorption measurements with supercritical car

  13. Precise and accurate determination of the 8B decay spectrum

    DEFF Research Database (Denmark)

    Kirsebom, Oliver Sølund; Hyldegaard, Solveig; Alcorta, M.;

    2011-01-01

    Accurate measurements of the 8B neutrino spectrum are important for the interpretation of solar neutrino data. Experimentally, the 8B neutrino spectrum can be obtained from the measurement of the β-delayed α spectrum. We report on an α-α coincidence measurement performed at the IGISOL facility in...

  14. Accurate determination of specific heat at high temperatures using the flash diffusivity method

    Science.gov (United States)

    Vandersande, J. W.; Zoltan, A.; Wood, C.

    1989-01-01

    The flash diffusivity method of Parker et al. (1961) was used to measure accurately the specific heat of test samples simultaneously with thermal diffusivity, thus obtaining the thermal conductivity of these materials directly. The accuracy of data obtained on two types of materials (n-type silicon-germanium alloys and niobium), was + or - 3 percent. It is shown that the method is applicable up to at least 1300 K.

  15. Decision peptide-driven: a free software tool for accurate protein quantification using gel electrophoresis and matrix assisted laser desorption ionization time of flight mass spectrometry.

    Science.gov (United States)

    Santos, Hugo M; Reboiro-Jato, Miguel; Glez-Peña, Daniel; Nunes-Miranda, J D; Fdez-Riverola, Florentino; Carvallo, R; Capelo, J L

    2010-09-15

    The decision peptide-driven tool implements a software application for assisting the user in a protocol for accurate protein quantification based on the following steps: (1) protein separation through gel electrophoresis; (2) in-gel protein digestion; (3) direct and inverse (18)O-labeling and (4) matrix assisted laser desorption ionization time of flight mass spectrometry, MALDI analysis. The DPD software compares the MALDI results of the direct and inverse (18)O-labeling experiments and quickly identifies those peptides with paralleled loses in different sets of a typical proteomic workflow. Those peptides are used for subsequent accurate protein quantification. The interpretation of the MALDI data from direct and inverse labeling experiments is time-consuming requiring a significant amount of time to do all comparisons manually. The DPD software shortens and simplifies the searching of the peptides that must be used for quantification from a week to just some minutes. To do so, it takes as input several MALDI spectra and aids the researcher in an automatic mode (i) to compare data from direct and inverse (18)O-labeling experiments, calculating the corresponding ratios to determine those peptides with paralleled losses throughout different sets of experiments; and (ii) allow to use those peptides as internal standards for subsequent accurate protein quantification using (18)O-labeling. In this work the DPD software is presented and explained with the quantification of protein carbonic anhydrase.

  16. A Simple yet Accurate Method for Students to Determine Asteroid Rotation Periods from Fragmented Light Curve Data

    Science.gov (United States)

    Beare, R. A.

    2008-01-01

    Professional astronomers use specialized software not normally available to students to determine the rotation periods of asteroids from fragmented light curve data. This paper describes a simple yet accurate method based on Microsoft Excel[R] that enables students to find periods in asteroid light curve and other discontinuous time series data of…

  17. Breakdown of anomalous channeling with ion energy for accurate strain determination in GaN-based heterostructures

    NARCIS (Netherlands)

    Redondo-Cubero, A.; Lorenz, K.; Gago, R.; Franco, N.; Fernandez-Garrido, S.; Smulders, P. J. M.; Munoz, E.; Calleja, E.; Watson, I. M.; Alves, E.

    2009-01-01

    The influence of the beam energy on the determination of strain state with ion channeling in GaN-based heterostructures (HSs) is addressed. Experimental results show that anomalous channeling may hinder an accurate analysis due to the steering effects at the HS interface, which are more intense at l

  18. Accurate method for determining vibration temperatures, and gain limitation in pulse RF-discharge CO2 laser

    Institute of Scientific and Technical Information of China (English)

    Hussain Badran; TIAN Zhao-shuo(田兆硕); WANG Qi(王祁)

    2004-01-01

    An accurate method of determining gain coefficients of pulse RF-discharge CO2 laser is developed,which involves the use of both the regular 00°1 and 00°2 laser transitions as probes of CO2 laser. The results indicate that the majority of transitions in discharge have anomalous gain coefficients under RF-discharge condition. This fact has not been generally recognized and the neglect of overlapping transitions can lead to errors in determining rotational temperature.

  19. A Precision Determination of the Φ Meson Mass

    Science.gov (United States)

    Pellinen, A.; Roos, M.

    1982-05-01

    From compilations of Kbar K mass histograms containing 25 080 phi mesons and bar pp mass histograms containing 33 260 ω mesons we determine the phi and the ω masses. In our fits the widths of the resonances are fixed and the mass and the resolution are free parameters. We then extrapolate to zero resolution with Orear's effective variance method which takes into account both mass and resolution errors. The results are mphi = (1019.67 ± 0.17) MeV and mω = (782.51 ± 0.82) MeV, where the errors are almost entirely systematic.

  20. Accurate determination of the free-free Gaunt factor; I - non-relativistic Gaunt factors

    CERN Document Server

    van Hoof, P A M; Volk, K; Chatzikos, M; Ferland, G J; Lykins, M; Porter, R L; Wang, Y

    2014-01-01

    Modern spectral synthesis codes need the thermally averaged free-free Gaunt factor defined over a very wide range of parameter space in order to produce an accurate prediction for the spectrum emitted by an ionized plasma. Until now no set of data exists that would meet this need in a fully satisfactory way. We have therefore undertaken to produce a table of very accurate non-relativistic Gaunt factors over a much wider range of parameters than has ever been produced before. We first produced a table of non-averaged Gaunt factors, covering the parameter space log10(epsilon_i) = -20 to +10 and log10(w) = -30 to +25. We then continued to produce a table of thermally averaged Gaunt factors covering the parameter space log10(gamma^2) = -6 to +10 and log10(u) = -16 to +13. Finally we produced a table of the frequency integrated Gaunt factor covering the parameter space log10(gamma^2) = -6 to +10. All the data presented in this paper are available online.

  1. Determining Protostar Masses: L1527 IRS in Taurus

    Science.gov (United States)

    Terebey, Susan; Isella, Andrea; De Vries, Christopher

    2013-07-01

    Protostar masses have been difficult to determine, in part due to the complex nature of protostar environments. We report on a pilot study to determine the mass of the L1527 protostar using CARMA interferometer data. The velocity channel maps are compared with a model that incorporates 1) LVG radiative transfer, 2) TSC collapse envelope and outflow cavity, and 3) a CARMA interferometer simulation. The models are able to reproduce observed C18O(2-1) channel maps quite well, and are sensitive to the gravity field of the infalling gas. The best-fit mass is 0.24 +/- 0.04 Mo for the L1527 protostar plus disk. The models indicate that line-width is a sensitive and robust indicator of mass. We conclude that this method of comparing millimeter interferometer data with infall models incorporating radiative transfer shows promise for determining a fundamental but poorly known quantity, the protostar mass.

  2. Precise top mass determination using lepton distribution at LHC

    CERN Document Server

    Kawabata, Sayaka

    2016-01-01

    We present a new method to measure a theoretically well-defined mass of the top quark at the LHC. This method uses lepton energy distribution and has a boost-invariant nature. We perform a simulation analysis of the top mass reconstruction with this method for tt -> lepton+jets channel at the leading order. We estimate several major uncertainties in the top mass determination and find that they are under good control.

  3. Rapid and Accurate Identification of Animal Species in Natural Leather Goods by Liquid Chromatography/Mass Spectrometry.

    Science.gov (United States)

    Izuchi, Yukari; Takashima, Tsuneo; Hatano, Naoya

    2016-01-01

    The demand for leather goods has grown globally in recent years. Industry revenue is forecast to reach $91.2 billion by 2018. There is an ongoing labelling problem in the leather items market, in that it is currently impossible to identify the species that a given piece of leather is derived from. To address this issue, we developed a rapid and simple method for the specific identification of leather derived from cattle, horses, pigs, sheep, goats, and deer by analysing peptides produced by the trypsin-digestion of proteins contained in leather goods using liquid chromatography/mass spectrometry. We determined species-specific amino acid sequences by liquid chromatography/tandem mass spectrometry analysis using the Mascot software program and demonstrated that collagen α-1(I), collagen α-2(I), and collagen α-1(III) from the dermal layer of the skin are particularly useful in species identification.

  4. A Simple Watt Balance for the Absolute Determination of Mass

    Science.gov (United States)

    Quinn, Terry; Quinn, Lucas; Davis, Richard

    2013-01-01

    A watt balance is an electromechanical device that allows a mass to be determined in terms of measurable electrical and mechanical quantities, themselves traceable to the fundamental constants of physics. International plans are well advanced to redefine the unit of mass, the kilogram, in terms of a fixed numerical value for the Planck constant. A…

  5. Experimental proposal for accurate determination of the phase relaxation time in highly excited quantum many-body systems

    CERN Document Server

    Bienert, M; Kun, S Yu

    2006-01-01

    We estimate how accurate the phase relaxation time of quantum many-body systems can be determined from data on forward peaking of evaporating protons from a compound nucleus. The angular range and accuracy of the data needed for a reliable determination of the phase relaxation time are evaluated. The general method is applied to analyze the inelastic scattering of 18 MeV protons from Pt for which previously measured double differential cross sections for two angles in the evaporating domain of the spectra show a strong forward peaking. A new experiment for an improved determination of the phase relaxation time is proposed.

  6. A generalised multiple-mass based method for the determination of the live mass of a force transducer

    Science.gov (United States)

    Montalvão, Diogo; Baker, Thomas; Ihracska, Balazs; Aulaqi, Muhammad

    2017-01-01

    Many applications in Experimental Modal Analysis (EMA) require that the sensors' masses are known. This is because the added mass from sensors will affect the structural mode shapes, and in particular its natural frequencies. EMA requires the measurement of the exciting forces at given coordinates, which is often made using piezoelectric force transducers. In such a case, the live mass of the force transducer, i.e. the mass as 'seen' by the structure in perpendicular directions must be measured somehow, so that compensation methods like mass cancelation can be performed. This however presents a problem on how to obtain an accurate measurement for the live mass. If the system is perfectly calibrated, then a reasonably accurate estimate can be made using a straightforward method available in most classical textbooks based on Newton's second law. However, this is often not the case (for example when the transducer's sensitivity changed over time, when it is unknown or when the connection influences the transmission of the force). In a self-calibrating iterative method, both the live mass and calibration factor are determined, but this paper shows that the problem may be ill-conditioned, producing misleading results if certain conditions are not met. Therefore, a more robust method is presented and discussed in this paper, reducing the ill-conditioning problems and the need to know the calibration factors beforehand. The three methods will be compared and discussed through numerical and experimental examples, showing that classical EMA still is a field of research that deserves the attention from scientists and engineers.

  7. Accurate determination of the binding energy of the formic acid dimer: The importance of geometry relaxation

    Science.gov (United States)

    Kalescky, Robert; Kraka, Elfi; Cremer, Dieter

    2014-02-01

    The formic acid dimer in its C2h-symmetrical cyclic form is stabilized by two equivalent H-bonds. The currently accepted interaction energy is 18.75 kcal/mol whereas the experimental binding energy D0 value is only 14.22 ±0.12 kcal/mol [F. Kollipost, R. W. Larsen, A. V. Domanskaya, M. Nörenberg, and M. A. Suhm, J. Chem. Phys. 136, 151101 (2012)]. Calculation of the binding energies De and D0 at the CCSD(T) (Coupled Cluster with Single and Double excitations and perturbative Triple excitations)/CBS (Complete Basis Set) level of theory, utilizing CCSD(T)/CBS geometries and the frequencies of the dimer and monomer, reveals that there is a 3.2 kcal/mol difference between interaction energy and binding energy De, which results from (i) not relaxing the geometry of the monomers upon dissociation of the dimer and (ii) approximating CCSD(T) correlation effects with MP2. The most accurate CCSD(T)/CBS values obtained in this work are De = 15.55 and D0 = 14.32 kcal/mol where the latter binding energy differs from the experimental value by 0.1 kcal/mol. The necessity of employing augmented VQZ and VPZ calculations and relaxing monomer geometries of H-bonded complexes upon dissociation to obtain reliable binding energies is emphasized.

  8. Rapid Screening of Bovine Milk Oligosaccharides in a Whey Permeate Product and Domestic Animal Milks by Accurate Mass Database and Tandem Mass Spectral Library.

    Science.gov (United States)

    Lee, Hyeyoung; Cuthbertson, Daniel J; Otter, Don E; Barile, Daniela

    2016-08-17

    A bovine milk oligosaccharide (BMO) library, prepared from cow colostrum, with 34 structures was generated and used to rapidly screen oligosaccharides in domestic animal milks and a whey permeate powder. The novel library was entered into a custom Personal Compound Database and Library (PCDL) and included accurate mass, retention time, and tandem mass spectra. Oligosaccharides in minute-sized samples were separated using nanoliquid chromatography (nanoLC) coupled to a high resolution and sensitive quadrupole-Time of Flight (Q-ToF) MS system. Using the PCDL, 18 oligosaccharides were found in a BMO-enriched product obtained from whey permeate processing. The usefulness of the analytical system and BMO library was further validated using milks from domestic sheep and buffaloes. Through BMO PCDL searching, 15 and 13 oligosaccharides in the BMO library were assigned in sheep and buffalo milks, respectively, thus demonstrating significant overlap between oligosaccharides in bovine (cow and buffalo) and ovine (sheep) milks. This method was shown to be an efficient, reliable, and rapid tool to identify oligosaccharide structures using automated spectral matching.

  9. Rapid and Accurate U-Th Dating of Ancient Carbonates using Inductively Coupled Plasma-Quadrupole Mass Spectrometry

    Science.gov (United States)

    Douville, Eric; Sallé, Eline; Frank, Norbert; Eisele, Markus; Pons-Branchu, Edwige; Ayrault, Sophie

    2010-05-01

    Here, the potential for rapid and accurate U-Th dating technique of marine aragonite skeletons (deep-sea corals, Lophelia pertusa) and secondary calcite deposits (speleothems and stalagmites) has been explored using inductively-coupled plasma-quadrupole mass spectrometry (ICP-QMS). The analytical procedure includes a largely simplified chemical separation technique for uranium (U) and thorium (Th) using UTEVA resin. The developed technique permits simultaneous quantification of uranium [238U] and thorium [232Th] concentrations and their respective isotopic composition, required for U-series disequilibrium dating. Up to 50 U-Th dates per day can be achieved through ICP-QMS with 234U and 230Th reproducibility (2sigma) of 3-4 permil and 1 percent, respectively. The high sensitivity (> 300 000 cps/ppb) together with low background (Porcupine Seabight (MD01-2463G, Mound Thérèse), indicating a purely interglacial growth of deep-water corals on so-called carbonate mounds over several climate cycles.

  10. Non-targeted screening for contaminants in paper and board food-contact materials using effect-directed analysis and accurate mass spectrometry.

    Science.gov (United States)

    Bengtström, Linda; Rosenmai, Anna Kjerstine; Trier, Xenia; Jensen, Lisbeth Krüger; Granby, Kit; Vinggaard, Anne Marie; Driffield, Malcolm; Højslev Petersen, Jens

    2016-06-01

    Due to large knowledge gaps in chemical composition and toxicological data for substances involved, paper and board food-contact materials (P&B FCM) have been emerging as a FCM type of particular concern for consumer safety. This study describes the development of a step-by-step strategy, including extraction, high-performance liquid chromatography (HPLC) fractionation, tentative identification of relevant substances and in vitro testing of selected tentatively identified substances. As a case study, we used two fractions from a recycled pizza box sample which exhibited aryl hydrocarbon receptor (AhR) activity. These fractions were analysed by gas chromatography (GC) and ultra-HPLC (UHPLC) coupled to quadrupole time-of-flight mass spectrometers (QTOF MS) in order tentatively to identify substances. The elemental composition was determined for peaks above a threshold, and compared with entries in a commercial mass spectral library for GC-MS (GC-EI-QTOF MS) analysis and an in-house built library of accurate masses for substances known to be used in P&B packaging for UHPLC-QTOF analysis. Of 75 tentatively identified substances, 15 were initially selected for further testing in vitro; however, only seven were commercially available and subsequently tested in vitro and quantified. Of these seven, the identities of three pigments found in printing inks were confirmed by UHPLC tandem mass spectrometry (QqQ MS/MS). Two pigments had entries in the database, meaning that a material relevant accurate mass database can provide a fast tentative identification. Pure standards of the seven tentatively identified substances were tested in vitro but could not explain a significant proportion of the AhR-response in the extract. Targeted analyses of dioxins and PCBs, both well-known AhR agonists, was performed. However, the dioxins could explain approximately 3% of the activity observed in the pizza box extract indicating that some very AhR active substance(s) still remain to be

  11. Optical coherence tomography enables accurate measurement of equine cartilage thickness for determination of speed of sound.

    Science.gov (United States)

    Puhakka, Pia H; Te Moller, Nikae C R; Tanska, Petri; Saarakkala, Simo; Tiitu, Virpi; Korhonen, Rami K; Brommer, Harold; Virén, Tuomas; Jurvelin, Jukka S; Töyräs, Juha

    2016-08-01

    Background and purpose - Arthroscopic estimation of articular cartilage thickness is important for scoring of lesion severity, and measurement of cartilage speed of sound (SOS)-a sensitive index of changes in cartilage composition. We investigated the accuracy of optical coherence tomography (OCT) in measurements of cartilage thickness and determined SOS by combining OCT thickness and ultrasound (US) time-of-flight (TOF) measurements. Material and methods - Cartilage thickness measurements from OCT and microscopy images of 94 equine osteochondral samples were compared. Then, SOS in cartilage was determined using simultaneous OCT thickness and US TOF measurements. SOS was then compared with the compositional, structural, and mechanical properties of cartilage. Results - Measurements of non-calcified cartilage thickness using OCT and microscopy were significantly correlated (ρ = 0.92; p measurement of articular cartilage thickness. Although SOS measurements lacked accuracy in thin equine cartilage, the concept of SOS measurement using OCT appears promising.

  12. Automated methods for accurate determination of the critical velocity of packed bed chromatography.

    Science.gov (United States)

    Chang, Yu-Chih; Gerontas, Spyridon; Titchener-Hooker, Nigel J

    2012-01-01

    Knowing the critical velocity (ucrit) of a chromatography column is an important part of process development as it allows the optimization of chromatographic flow conditions. The conventional flow step method for determining ucrit is prone to error as it depends heavily on human judgment. In this study, two automated methods for determining ucrit have been developed: the automatic flow step (AFS) method and the automatic pressure step (APS) method. In the AFS method, the column pressure drop is monitored upon application of automated incremental increases in flow velocity, whereas in the APS method the flow velocity is monitored upon application of automated incremental increases in pressure drop. The APS method emerged as the one with the higher levels of accuracy, efficiency and ease of application having the greater potential to assist defining the best operational parameters of a chromatography column.

  13. Neutrino mass hierarchy determination at reactor antineutrino experiments

    CERN Document Server

    Yang, Guang

    2015-01-01

    After the neutrino mixing angle $\\theta_{13}$ has been precisely measured by the reactor antineutrino experiments, one of the most important open questions left in neutrino physics is the neutrino mass hierarchy. Jiangmen Underground Neutrino Observatory (JUNO) is designed to determine the neutrino mass hierarchy (MH) without exploring the matter effect. The JUNO site location is optimized to have the best sensitivity for the mass hierarchy determination. JUNO will employ a 20 kton liquid scintillator detector located in a laboratory 700 meters underground. The excellent energy resolution and PMT coverage will give us an unprecedented opportunity to reach a 3-4 $\\sigma$ precision. In this paper, the JUNO detector design and simulation work will be presented. Also, RENO-50, another medium distance reactor antineutrino experiment, will do a similar measurement. With the efforts of these experiments, it is very likely that the neutrino mass hierarchy will be determined in the next 10 years.

  14. Structural determination of intact proteins using mass spectrometry

    Science.gov (United States)

    Kruppa, Gary; Schoeniger, Joseph S.; Young, Malin M.

    2008-05-06

    The present invention relates to novel methods of determining the sequence and structure of proteins. Specifically, the present invention allows for the analysis of intact proteins within a mass spectrometer. Therefore, preparatory separations need not be performed prior to introducing a protein sample into the mass spectrometer. Also disclosed herein are new instrumental developments for enhancing the signal from the desired modified proteins, methods for producing controlled protein fragments in the mass spectrometer, eliminating complex microseparations, and protein preparatory chemical steps necessary for cross-linking based protein structure determination.Additionally, the preferred method of the present invention involves the determination of protein structures utilizing a top-down analysis of protein structures to search for covalent modifications. In the preferred method, intact proteins are ionized and fragmented within the mass spectrometer.

  15. Accurate determination of frequency dependent three element equivalent circuit for symmetric step microstrip discontinuity

    Science.gov (United States)

    Webster, M. J.; Easter, B.; Hornsby, J. S.

    1990-02-01

    A three element frequency dependent equivalent circuit which characterizes a symmetric step microstrip discontinuity is determined using the method of lines. This method was applied so as to exploit to the full the processing capabilities of the available Cyber 205 computer, and to obtain results with the highest possible accuracy at frequencies in the range 4-16 GHz. Numerical values of scattering parameters are given for three geometries.

  16. Accurate Determination of the Frequency Response Function of Submerged and Confined Structures by Using PZT-Patches †

    Science.gov (United States)

    Presas, Alexandre; Valentin, David; Egusquiza, Eduard; Valero, Carme; Egusquiza, Mònica; Bossio, Matias

    2017-01-01

    To accurately determine the dynamic response of a structure is of relevant interest in many engineering applications. Particularly, it is of paramount importance to determine the Frequency Response Function (FRF) for structures subjected to dynamic loads in order to avoid resonance and fatigue problems that can drastically reduce their useful life. One challenging case is the experimental determination of the FRF of submerged and confined structures, such as hydraulic turbines, which are greatly affected by dynamic problems as reported in many cases in the past. The utilization of classical and calibrated exciters such as instrumented hammers or shakers to determine the FRF in such structures can be very complex due to the confinement of the structure and because their use can disturb the boundary conditions affecting the experimental results. For such cases, Piezoelectric Patches (PZTs), which are very light, thin and small, could be a very good option. Nevertheless, the main drawback of these exciters is that the calibration as dynamic force transducers (relationship voltage/force) has not been successfully obtained in the past. Therefore, in this paper, a method to accurately determine the FRF of submerged and confined structures by using PZTs is developed and validated. The method consists of experimentally determining some characteristic parameters that define the FRF, with an uncalibrated PZT exciting the structure. These parameters, which have been experimentally determined, are then introduced in a validated numerical model of the tested structure. In this way, the FRF of the structure can be estimated with good accuracy. With respect to previous studies, where only the natural frequencies and mode shapes were considered, this paper discuss and experimentally proves the best excitation characteristic to obtain also the damping ratios and proposes a procedure to fully determine the FRF. The method proposed here has been validated for the structure vibrating

  17. CLASH-VLT: CONSTRAINTS ON THE DARK MATTER EQUATION OF STATE FROM ACCURATE MEASUREMENTS OF GALAXY CLUSTER MASS PROFILES

    Energy Technology Data Exchange (ETDEWEB)

    Sartoris, Barbara; Borgani, Stefano; Girardi, Marisa [Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, Via Tiepolo 11, I-34143 Trieste (Italy); Biviano, Andrea; Balestra, Italo; Nonino, Mario [INAF/Osservatorio Astronomico di Trieste, Via Tiepolo 11, I-34143 Trieste (Italy); Rosati, Piero [Dipartimento di Fisica e Scienze della Terra, Universita' di Ferrara, Via Saragat 1, I-44122 Ferrara (Italy); Umetsu, Keiichi; Czakon, Nicole [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Bartelmann, Matthias [Zentrum für Astronomie der Universität Heidelberg, ITA, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Grillo, Claudio [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Lemze, Doron; Medezinski, Elinor [Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Zitrin, Adi [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Mercurio, Amata [INAF/Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli (Italy); Postman, Marc; Bradley, Larry; Coe, Dan [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Broadhurst, Tom [Department of Theoretical Physics, University of the Basque Country, P.O. Box 644, E-48080 Bilbao (Spain); Melchior, Peter, E-mail: sartoris@oats.inaf.it [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); and others

    2014-03-01

    A pressureless scenario for the dark matter (DM) fluid is a widely adopted hypothesis, despite the absence of direct observational evidence. According to general relativity, the total mass-energy content of a system shapes the gravitational potential well, but different test particles perceive this potential in different ways depending on their properties. Cluster galaxy velocities, being <mass. We exploit this phenomenon to constrain the equation of state (EoS) parameter of the fluid, primarily DM, contained in galaxy clusters. We use complementary information provided by the kinematic and lensing mass profiles of the galaxy cluster MACS 1206.2–0847 at z = 0.44, as obtained in an extensive imaging and spectroscopic campaign within the Cluster Lensing And Supernova survey with Hubble. The unprecedented high quality of our data set and the properties of this cluster are well suited to determine the EoS parameter of the cluster fluid. Since baryons contribute at most 15% to the total mass in clusters and their pressure is negligible, the EoS parameter we derive describes the behavior of the DM fluid. We obtain the most stringent constraint on the DM EoS parameter to date, w = (p{sub r} + 2 p{sub t} )/(3 c {sup 2}ρ) = 0.00 ± 0.15 (stat) ± 0.08 (syst), averaged over the radial range 0.5 Mpc ≤ r ≤ r {sub 200}, where p{sub r} and p{sub t} are the radial and tangential pressure, and ρ is the density. We plan to further improve our constraint by applying the same procedure to all clusters from the ongoing Cluster Lensing And Supernova Survey with Hubble-Very Large Telescope program.

  18. Accurate determination of the diffusion coefficient of proteins by Fourier analysis with whole column imaging detection.

    Science.gov (United States)

    Zarabadi, Atefeh S; Pawliszyn, Janusz

    2015-02-17

    Analysis in the frequency domain is considered a powerful tool to elicit precise information from spectroscopic signals. In this study, the Fourier transformation technique is employed to determine the diffusion coefficient (D) of a number of proteins in the frequency domain. Analytical approaches are investigated for determination of D from both experimental and data treatment viewpoints. The diffusion process is modeled to calculate diffusion coefficients based on the Fourier transformation solution to Fick's law equation, and its results are compared to time domain results. The simulations characterize optimum spatial and temporal conditions and demonstrate the noise tolerance of the method. The proposed model is validated by its application for the electropherograms from the diffusion path of a set of proteins. Real-time dynamic scanning is conducted to monitor dispersion by employing whole column imaging detection technology in combination with capillary isoelectric focusing (CIEF) and the imaging plug flow (iPF) experiment. These experimental techniques provide different peak shapes, which are utilized to demonstrate the Fourier transformation ability in extracting diffusion coefficients out of irregular shape signals. Experimental results confirmed that the Fourier transformation procedure substantially enhanced the accuracy of the determined values compared to those obtained in the time domain.

  19. Two-dimensional flow nanometry of biological nanoparticles for accurate determination of their size and emission intensity

    Science.gov (United States)

    Block, Stephan; Fast, Björn Johansson; Lundgren, Anders; Zhdanov, Vladimir P.; Höök, Fredrik

    2016-09-01

    Biological nanoparticles (BNPs) are of high interest due to their key role in various biological processes and use as biomarkers. BNP size and composition are decisive for their functions, but simultaneous determination of both properties with high accuracy remains challenging. Optical microscopy allows precise determination of fluorescence/scattering intensity, but not the size of individual BNPs. The latter is better determined by tracking their random motion in bulk, but the limited illumination volume for tracking this motion impedes reliable intensity determination. Here, we show that by attaching BNPs to a supported lipid bilayer, subjecting them to hydrodynamic flows and tracking their motion via surface-sensitive optical imaging enable determination of their diffusion coefficients and flow-induced drifts, from which accurate quantification of both BNP size and emission intensity can be made. For vesicles, the accuracy of this approach is demonstrated by resolving the expected radius-squared dependence of their fluorescence intensity for radii down to 15 nm.

  20. Two-Dimensional Flow Nanometry of Biological Nanoparticles for Accurate Determination of Their Size and Emission Intensity

    CERN Document Server

    Block, Stephan; Lundgren, Anders; Zhdanov, Vladimir P; Höök, Fredrik

    2016-01-01

    Biological nanoparticles (BNPs) are of high interest due to their key role in various biological processes and use as biomarkers. BNP size and molecular composition are decisive for their functions, but simultaneous determination of both properties with high accuracy remains challenging, which is a severe limitation. Surface-sensitive microscopy allows one to precisely determine fluorescence or scattering intensity, but not the size of individual BNPs. The latter is better determined by tracking their random motion in bulk, but the limited illumination volume for tracking this motion impedes reliable intensity determination. We here show that attaching BNPs (specifically, vesicles and functionalized gold NPs) to a supported lipid bilayer, subjecting them to a hydrodynamic flow, and tracking their motion via surface-sensitive imaging enable to determine their diffusion coefficients and flow-induced drift velocities and to accurately quantify both BNP size and emission intensity. For vesicles, the high accuracy...

  1. Rapid and accurate determination of barium by instrumental neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Armelin, Maria Jose A.; Maihara, Vera A.; Saiki, Mitiko, E-mail: marmelin@ipen.br, E-mail: vmaihara@ipen.br, E-mail: mitiko@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Trevizam, Anderson R., E-mail: aanrt@hotmail.com [Universidade Estadual do Centro Oeste (UNICENTRO), Guarapuava, PR (Brazil)

    2013-07-01

    Barium is an alkaline earth metal naturally present in soils. When available at a high level in the soil it can cause toxicity to plants and animals. Not all the barium is readily available to living organisms. Inorganic and organic barium compounds can be presented as soluble or insoluble forms in the soil. The soluble form of BaS is extremely toxic to humans, animals and plants. Researchers have noted a decrease of K absorption in the plant when Ba concentrations are increased and a change in overall plant growth. In case of animals, Ba tends to be concentrated in the bones which may compete with calcium, although only about 2% barium ingested in dietary is absorbed by the body. Another effect is that the Ba can interfere with the availability of sulfur in the soil due to the sulphate formation of low solubility. Barium and some other elements are considered palioclimatic proxies. For some researchers, barite is perhaps the most appropriate indicator of paleoproductivity because of a high resistance to dissolution. As explained about the barium effects in various situations, it was considered important to study the more appropriated experimental conditions for determination of this element by INAA. Conditions established for this analysis were: a) Irradiation time, 15 and 40 seconds, under thermal flux neutron about 4 x 10{sup 12} n cm{sup -2} s{sup -1}, for determining barium in geological and biological matrices, respectively; b) Decay time, approximately of 4 minutes; c) Counting time of 30 minutes; d) Radionuclide measured {sup 139}Ba. The quality of Ba results was evaluated from the analysis of certified reference materials. The performance of the method was satisfactory, according to the criterion of E.ζ score. Results obtained in this study indicate INAA is a good alternative for Ba determination in geological and biological samples. (author)

  2. Raman spectroscopy provides a powerful diagnostic tool for accurate determination of albumin glycation.

    Directory of Open Access Journals (Sweden)

    Narahara Chari Dingari

    Full Text Available We present the first demonstration of glycated albumin detection and quantification using Raman spectroscopy without the addition of reagents. Glycated albumin is an important marker for monitoring the long-term glycemic history of diabetics, especially as its concentrations, in contrast to glycated hemoglobin levels, are unaffected by changes in erythrocyte life times. Clinically, glycated albumin concentrations show a strong correlation with the development of serious diabetes complications including nephropathy and retinopathy. In this article, we propose and evaluate the efficacy of Raman spectroscopy for determination of this important analyte. By utilizing the pre-concentration obtained through drop-coating deposition, we show that glycation of albumin leads to subtle, but consistent, changes in vibrational features, which with the help of multivariate classification techniques can be used to discriminate glycated albumin from the unglycated variant with 100% accuracy. Moreover, we demonstrate that the calibration model developed on the glycated albumin spectral dataset shows high predictive power, even at substantially lower concentrations than those typically encountered in clinical practice. In fact, the limit of detection for glycated albumin measurements is calculated to be approximately four times lower than its minimum physiological concentration. Importantly, in relation to the existing detection methods for glycated albumin, the proposed method is also completely reagent-free, requires barely any sample preparation and has the potential for simultaneous determination of glycated hemoglobin levels as well. Given these key advantages, we believe that the proposed approach can provide a uniquely powerful tool for quantification of glycation status of proteins in biopharmaceutical development as well as for glycemic marker determination in routine clinical diagnostics in the future.

  3. Raman spectroscopy provides a powerful diagnostic tool for accurate determination of albumin glycation.

    Science.gov (United States)

    Dingari, Narahara Chari; Horowitz, Gary L; Kang, Jeon Woong; Dasari, Ramachandra R; Barman, Ishan

    2012-01-01

    We present the first demonstration of glycated albumin detection and quantification using Raman spectroscopy without the addition of reagents. Glycated albumin is an important marker for monitoring the long-term glycemic history of diabetics, especially as its concentrations, in contrast to glycated hemoglobin levels, are unaffected by changes in erythrocyte life times. Clinically, glycated albumin concentrations show a strong correlation with the development of serious diabetes complications including nephropathy and retinopathy. In this article, we propose and evaluate the efficacy of Raman spectroscopy for determination of this important analyte. By utilizing the pre-concentration obtained through drop-coating deposition, we show that glycation of albumin leads to subtle, but consistent, changes in vibrational features, which with the help of multivariate classification techniques can be used to discriminate glycated albumin from the unglycated variant with 100% accuracy. Moreover, we demonstrate that the calibration model developed on the glycated albumin spectral dataset shows high predictive power, even at substantially lower concentrations than those typically encountered in clinical practice. In fact, the limit of detection for glycated albumin measurements is calculated to be approximately four times lower than its minimum physiological concentration. Importantly, in relation to the existing detection methods for glycated albumin, the proposed method is also completely reagent-free, requires barely any sample preparation and has the potential for simultaneous determination of glycated hemoglobin levels as well. Given these key advantages, we believe that the proposed approach can provide a uniquely powerful tool for quantification of glycation status of proteins in biopharmaceutical development as well as for glycemic marker determination in routine clinical diagnostics in the future.

  4. Fast and accurate expression for the Voigt function. Application to the determination of uranium M linewidths

    Energy Technology Data Exchange (ETDEWEB)

    Limandri, Silvina P. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina); Bonetto, Rita D. [Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina) and Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco, Calle 47 No 257, 1900 La Plata, Argentina; Facultad de Ciencias Exactas y Facultad de Ingenieria de la UNLP, La Plata (Argentina); Di Rocco, Hector O. [Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina); Instituto de Fisica Arroyo Seco, Facultad de Ciencias Exactas, Universidad Nacional del Centro, Pinto 399, 7000 Tandil (Argentina); Trincavelli, Jorge C. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina)], E-mail: jorge@quechua.fis.uncor.edu

    2008-09-15

    The Voigt function is the convolution between a Gaussian and a Lorentzian distribution. The numerical implementation of this function is required in diverse areas of physics and applied mathematics. An explicit representation for the Voigt function is developed in terms of series of trigonometric and hyperbolic functions. The obtained expression permits a very fast evaluation of Voigt profiles with a degree of accuracy higher than the one required for spectroscopy applications. In addition, this expression is implemented in a numerical algorithm of parameter optimization in electron probe microanalysis, and applied to determine natural linewidths for several transitions to the uranium M levels.

  5. A precise and accurate determination of the cosmic microwave background temperature at z=0.89

    CERN Document Server

    Muller, S; Black, J H; Curran, S J; Horellou, C; Aalto, S; Combes, F; Guelin, M; Henkel, C

    2012-01-01

    According to the Big Bang theory and as a consequence of adiabatic expansion of the Universe, the temperature of the cosmic microwave background (CMB) increases linearly with redshift. This relation is, however, poorly explored, and detection of any deviation would directly lead to (astro-)physics beyond the standard model. We aim at measuring the temperature of the CMB with an accuracy of a few percent at z=0.89 toward the molecular absorber in the galaxy lensing the quasar PKS1830-211. We adopt a Monte-Carlo Markov Chain approach, coupled with predictions from the non-LTE radiative transfer code RADEX, to solve the excitation of a set of various molecular species directly from their spectra. We determine Tcmb=5.08 pm 0.10 K at 68% confidence level. Our measurement is consistent with the value Tcmb=5.14 K predicted by the standard cosmological model with adiabatic expansion of the Universe. This is the most precise determination of Tcmb at z>0 to date.

  6. An accurate determination of the Hubble constant from Baryon Acoustic Oscillation datasets

    CERN Document Server

    Cheng, Cheng

    2014-01-01

    Even though the Hubble constant cannot be significantly determined by the low-redshift Baryon Acoustic Oscillation (BAO) data alone, it can be tightly constrained once the high-redshift BAO data are combined. Combining BAO data from 6dFGS, BOSS DR11 clustering of galaxies, WiggleZ and $z=2.34$ from BOSS DR11 quasar Lyman-$\\alpha$ forest lines, we get $H_0=68.17^{+1.55}_{-1.56}$ km s$^{-1}$ Mpc$^{-1}$. In addition, adopting the the simultaneous measurements of $H(z)$ and $D_A(z)$ from the two-dimensional two-point correlation function from BOSS DR9 CMASS sample and two-dimensional matter power spectrum from SDSS DR7 sample, we obtain $H_0=68.11\\pm1.69$ km s$^{-1}$ Mpc$^{-1}$. Finally, combining all of the BAO datasets, we conclude $H_0=68.11\\pm 0.86$ km s$^{-1}$ Mpc$^{-1}$, a 1.3% determination.

  7. Standard addition strip for quantitative electrostatic spray ionization mass spectrometry analysis: determination of caffeine in drinks.

    Science.gov (United States)

    Tobolkina, Elena; Qiao, Liang; Roussel, Christophe; Girault, Hubert H

    2014-12-01

    Standard addition strips were prepared for the quantitative determination of caffeine in different beverages by electrostatic spray ionization mass spectrometry (ESTASI-MS). The gist of this approach is to dry spots of caffeine solutions with different concentrations on a polymer strip, then to deposit a drop of sample mixed with an internal standard, here theobromine on each spot and to measure the mass spectrometry signals of caffeine and theobromine by ESTASI-MS. This strip approach is very convenient and provides quantitative analyses as accurate as the classical standard addition method by MS or liquid chromatography.

  8. Accurate Determination of Reference Scales for Wilson Gauge Action from Yang--Mills Gradient Flow

    CERN Document Server

    Asakawa, Masayuki; Iritani, Takumi; Itou, Etsuko; Kitazawa, Masakiyo; Suzuki, Hiroshi

    2015-01-01

    A high precision parametrization of the lattice spacing ($a$) in terms of the bare coupling ($\\beta$) for the SU(3) Yang--Mills theory with the Wilson gauge action is given in a wide range of $\\beta$ with high accuracy. The Yang--Mills gradient flow with respect to the flow time $t$ for the dimensionless observable, $t\\frac{d}{dt}t^2\\langle E(t)\\rangle$, is utilized to determine the parametrization. With fine lattice spacings ($6.3\\le\\beta\\le7.5$) and large lattice volumes ($N_{\\rm s}=64$--$128$), the discretization and finite-volume errors are significantly reduced to the same level as the statistical error. With this lattice setup, the lattice and perturbative estimates of $t^2\\langle E\\rangle$ are also compared as a function of $t$.

  9. Accurate Determination of Geographical Origin of Tea Based on Terahertz Spectroscopy

    Directory of Open Access Journals (Sweden)

    Mingliang Li

    2017-02-01

    Full Text Available This paper proposes a structured model for the identification of green tea, as well as tracing its geographical origins. Considering that the features of different types of green tea are similar under THz time-domain spectroscopy, we designed a program to perform principal component analysis (PCA of the spectroscopic data of various green tea samples and to determine the data sequences of principal components. We then established a training set for the principal components to train a support vector machine (SVM model via a genetic algorithm (GA. We used this model to optimize the parameters and develop a GA-based SVM model with an identification rate of 96.25% for the tested samples. Taken together, our results confirm that THz time-domain spectroscopy combined with GA-SVM can be effectively applied to rapidly identify types of green tea with different geographical origins.

  10. CYP450 phenotyping and accurate mass identification of metabolites of the 8-aminoquinoline, anti-malarial drug primaquine

    Directory of Open Access Journals (Sweden)

    Pybus Brandon S

    2012-08-01

    Full Text Available Abstract Background The 8-aminoquinoline (8AQ drug primaquine (PQ is currently the only approved drug effective against the persistent liver stage of the hypnozoite forming strains Plasmodium vivax and Plasmodium ovale as well as Stage V gametocytes of Plasmodium falciparum. To date, several groups have investigated the toxicity observed in the 8AQ class, however, exact mechanisms and/or metabolic species responsible for PQ’s haemotoxic and anti-malarial properties are not fully understood. Methods In the present study, the metabolism of PQ was evaluated using in vitro recombinant metabolic enzymes from the cytochrome P450 (CYP and mono-amine oxidase (MAO families. Based on this information, metabolite identification experiments were performed using nominal and accurate mass measurements. Results Relative activity factor (RAF-weighted intrinsic clearance values show the relative role of each enzyme to be MAO-A, 2C19, 3A4, and 2D6, with 76.1, 17.0, 5.2, and 1.7% contributions to PQ metabolism, respectively. CYP 2D6 was shown to produce at least six different oxidative metabolites along with demethylations, while MAO-A products derived from the PQ aldehyde, a pre-cursor to carboxy PQ. CYPs 2C19 and 3A4 produced only trace levels of hydroxylated species. Conclusions As a result of this work, CYP 2D6 and MAO-A have been implicated as the key enzymes associated with PQ metabolism, and metabolites previously identified as potentially playing a role in efficacy and haemolytic toxicity have been attributed to production via CYP 2D6 mediated pathways.

  11. Kinematic Cusps: Determining the Missing Particle Mass at the LHC

    CERN Document Server

    Han, Tao; Song, Jeonghyeon

    2009-01-01

    Neutral massive stable particles (dark matter candidates) are produced at colliders in pairs, due to an exact symmetry called a ``parity''. They escape from detection, rendering their mass measurement difficult. We consider the pair production of these stable particles associated with two observable particles, from a two-step cascade decay of a heavier particle with even parity, via an intermediate particle with odd parity. We observe kinematic cusp structures in the invariant mass and angular distributions of the observable particles. Knowing the parent mass from direct resonant decay into Standard Model particles, one can determine the missing particle mass as well as the intermediate particle mass by using the cusped peak and end point of the distributions. The shape of the cusp distribution does not depend on the spin correlation.

  12. Accurate Determination of Rotational Energy Levels in the Ground State of ^{12}CH_4

    Science.gov (United States)

    Abe, M.; Iwakuni, K.; Okubo, S.; Sasada, H.

    2013-06-01

    We have measured absolute frequencies of saturated absorption of 183 allowed and 21 forbidden transitions in the νb{3} band of ^{12}CH_4 using an optical comb-referenced difference-frequency-generation spectrometer from 86.8 to 93.1 THz (from 2890 to 3100 wn). The pump and signal sources are a 1.06-μ m Nd:YAG laser and a 1.5-μ m extended-cavity laser diode. An enhanced-cavity absorption cell increases the optical electric field and enhances the sensitivity. The typical uncertainty is 3 kHz for the allowed transitions and 12 kHz for the forbidden transitions. Twenty combination differences are precisely determined, and the scalar rotational and centrifugal distortion constants of the ground state are thereby yielded as r@ = l@ r@ = l B_{{s}} (157 122 614.2 ± 1.5) kHz, D_{{s}} (3 328.545 ± 0.031) kHz, H_{{s}} (190.90 ± 0.26) Hz, and L_{{s}} (-13.16 ± 0.76) mHz. Here, B_{{s}} is the rotational constant and D_{{s}}, H_{{s}} and L_{{s}} are the scalar quartic, sextic, octic distortion constants. The relative uncertainties are considerably smaller than those obtained from global analysis of Fourier-transform infrared spectroscopy. S. Okubo, H. Nakayama, K. Iwakuni, H. Inaba and H. Sasada, Opt. Express 19, 23878 (2011). M. Abe, K. Iwakuni, S. Okubo, and H. Sasada, J. Opt. Soc. Am. B (to be published). S. Albert, S. Bauerecker, V. Boudon, L. R. Brown, J. -P. Champion, M. Loëte, A. Nikitin, and M. Quack, Chem. Phys. 356, 131 (2009).

  13. A rugged, precise and accurate new gravimetry method for the determination of gold: an alternative to fire assay method.

    Science.gov (United States)

    Singh, Nahar

    2012-01-01

    A new, rugged, precise, accurate and fast primary method of measurement has been proposed for the determination of gold in various gold articles. Precise and accurate measurement of gold is the primary requirement for hall marking and to trade gold internationally, as billions of dollars of gold are trading world wide for the various applications. At present Fire Assay ASTM E 1335-08 is the only Standard Test Method for the determination of Gold, which is accepted internationally. But the method is time consuming, cumbersome and required expertise to perform the test. In the present investigation, a method has been developed gravimetry based on direct determination of gold after reducing gold in zero-valent state by hydroxylamine hydrochloride. Gravimetry is the most reliable technique and having highest metrological qualities in comparison to titremetry and instrumental method and the results of gravimetry are directly traceable to SI unit. The results of gravimetric method are accepted without reference to a standard of the same quantity. Several experiments were carried out with and without impurities and it has been concluded that gold can be determined accurately and precisely in presence of several impurities. Five replicates of approximate 0.2 g gold samples were analyzed following method proposed and percentage purity were found to be 99.993 ± 0.0056 with 95% confidence level (k = 2). The combined uncertainty in gold measurement has also been evaluated using potential sources of the method according to the EURACHEM/GUM guidelines.

  14. [Determination of Virtual Surgery Mass Point Spring Model Parameters Based on Genetic Algorithms].

    Science.gov (United States)

    Chen, Ying; Hu, Xuyi; Zhu, Qiguang

    2015-12-01

    Mass point-spring model is one of the commonly used models in virtual surgery. However, its model parameters have no clear physical meaning, and it is hard to set the parameter conveniently. We, therefore, proposed a method based on genetic algorithm to determine the mass-spring model parameters. Computer-aided tomography (CAT) data were used to determine the mass value of the particle, and stiffness and damping coefficient were obtained by genetic algorithm. We used the difference between the reference deformation and virtual deformation as the fitness function to get the approximate optimal solution of the model parameters. Experimental results showed that this method could obtain an approximate optimal solution of spring parameters with lower cost, and could accurately reproduce the effect of the actual deformation model as well.

  15. The selective determination of sulfates, sulfonates, and phosphates in urine by capillary electrophoresis/mass spectrometry.

    Science.gov (United States)

    Bunz, Svenja-Catharina; Neusüß, Christian

    2013-01-01

    Metabolite identification and metabolite profiling are of major importance in the pharmaceutical and clinical context. However, anions of biological relevance such as sulfates, sulfonates, and phosphates are rarely included in common techniques for metabolite studies. In this protocol, we demonstrate a unique method to selectively determine these anions. The method comprises a capillary electrophoresis separation using an acidic background electrolyte (pH ≤ 2) and anodic detection by mass spectrometry via negative electrospray ionization. In this way, only anions of strong acids like sulfates are determined. The selectivity for sulfur-containing species is proved based on the specific isotopic ratios. In conjunction with the accurate mass from the time-of-flight mass spectrometer, the presented method is well suited for clinical and pharmaceutical applications to identify possible metabolites and to quantify known metabolites.

  16. Determining the Spatially Resolved Mass Outflow Rate in Markarian 573

    Science.gov (United States)

    Revalski, Mitchell; Crenshaw, D. Michael; Fischer, Travis C.; Kraemer, Steven B.; Schmitt, Henrique R.

    2017-01-01

    We report on current progress in calculating the narrow line region (NLR) mass outflow rate in the Seyfert 2 galaxy Markarian 573. Our goal is to determine the mass outflow rate as a function of distance from the nucleus in 10 nearby Active Galactic Nuclei (AGN) with spatially resolved NLRs. These nearby AGN allow us to study the feeding and feedback of supermassive black holes (SMBHs) that may play an important role in understanding large scale structure, enrichment of the interstellar medium, and coevolution of SMBHs with their host galaxies. Utilizing archival spectra from the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) we measured emission line ratios from a wide range of ionized species. Next we used the line ratios to find a reddening correction and determined the physical conditions in the ionized gas using the photoionization code Cloudy. Specifically, we derived the mass of the ionized gas and then estimate the total mass outside of the spectral slit using HST [O III] images. Combined with kinematic models of the outflows we will determine the mass outflow rate and kinetic luminosity as a function of distance from the central AGN. Ultimately, we aim to determine if NLR outflows are effective in regulating AGN feedback by comparing our observed outflow rates with theoretical models.

  17. Computational Algorithm for Orbit and Mass Determination of Visual Binaries

    CERN Document Server

    Sharaf, Mohamed; Saad, Abdel Naby; Elkhateeb, Magdy; Saad, Somaya

    2014-01-01

    In this paper we introduce an algorithm for determining the orbital elements and individual masses of visual binaries. The algorithm uses an optimal point, which minimizes a specific function describing the average length between the least-squares solution and the exact solution. The objective function to be minimized is exact, without any approximation. The algorithm is applied to Kowalsky's method for orbital parameter computation, and to Reed's method for the determination of the dynamical parallax and individual masses. The procedure is applied to A 1145 and ADS 15182.

  18. Note: Accurate determination of thickness of multiple layers of thin film deposited on a piezoelectric quartz crystal.

    Science.gov (United States)

    Wajid, Abdul

    2013-10-01

    Modern day piezoelectric quartz crystal microbalances for thin film deposition control are based on Z-match equation, which is mathematically valid for deposition of a single material on a given quartz crystal. When multiple layers are deposited, thickness and deposition rate errors accumulate due to mismatch of acoustic impedance of different materials. Here we present a novel method, based on the acoustic transfer matrix formalism, for accurate determination of thickness of an arbitrary number of layers of dissimilar materials deposited on a quartz crystal. Laboratory data show excellent accuracy of the method compared to conventional Z-match equation.

  19. Accurate determination of the absolute phase and temporal-pulse phase of few-cycle laser pulses

    Institute of Scientific and Technical Information of China (English)

    Xia Ke-Yu; Gong Shang-Qing; Niu Yue-Ping; Li Ru-Xin; Xu Zhi-Zhan

    2007-01-01

    A Fourier analysis method is used to accurately determine not only the absolute phase but also the temporalpulse phase of an isolated few-cycle (chirped) laser pulse. This method is independent of the pulse shape and can fully characterize the light wave even though only a few samples per optical cycle are available. It paves the way for investigating the absolute phase-dependent extreme nonlinear optics, and the evolutions of the absolute phase and the temporal-pulse phase of few-cycle laser pulses.

  20. Fast and accurate determination of 3D temperature distribution using fraction-step semi-implicit method

    Science.gov (United States)

    Cen, Wei; Hoppe, Ralph; Gu, Ning

    2016-09-01

    In this paper, we proposed a method to numerically determinate 3-dimensional thermal response due to electromagnetic exposure quickly and accurately. Due to the stability criterion the explicit finite-difference time-domain (FDTD) method works fast only if the spatial step is not set very small. In this paper, the semi-implicit Crank-Nicholson method for time domain discretization with unconditional time stability is proposed, where the idea of fractional steps method was utilized in 3-dimension so that an efficient numerical implementation is obtained. Compared with the explicit FDTD, with similar numerical precision, the proposed method takes less than 1/200 of the execution time.

  1. Ultra-high-performance liquid chromatography electrospray ionization tandem mass spectrometry for accurate analysis of glycerophospholipids and sphingolipids in drug resistance tumor cells.

    Science.gov (United States)

    Li, Lin; Wang, Linlin; Shangguan, Dihua; Wei, Yanbo; Han, Juanjuan; Xiong, Shaoxiang; Zhao, Zhenwen

    2015-02-13

    Glycerophospholipids and sphingolipids are important signaling molecules which are involved in many physiological and pathological processes. Here we reported an effective method for accurate analysis of these lipids by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The methanol method was adopted for extraction of lipids due to its simplicity and high efficiency. It was found that two subclasses of sphingolipids, sulfatide (ST) and cerebroside (CB), were heat labile, so a decreased temperature in the ion source of MS might be necessary for these compounds analysis. In addition, it was found that the isobaric interferences were commonly existent, for example, the m/z of 16:0/18:1 PC containing two (13)C isotope being identical to that of 16:0/18:0 PC determined by a unit mass resolution mass spectrometer; therefore, a baseline separation of interferential species was required to maintain selectivity and accuracy of analysis. In this work, an ultra-high-performance liquid chromatography (UHPLC)-based method was developed for separation of interferential species. Moreover, in order to deal with the characteristics of different polarity and wide dynamic range of glycerophospholipids and sphingolipids in biological systems, three detecting conditions were combined together for comprehensive and rational analysis of glycerophospholipids and sphingolipids. The method was utilized to profile glycerophospholipids and sphingolipids in drug resistant tumor cells. Our results showed that many lipids were significantly changed in drug resistant tumor cells compared to paired drug sensitive tumor cells. This is a systematic report about the isobaric interferences and heat labile compounds interferences when analyzing glycerophospholipids and sphingolipids by ESI-MS/MS, which aids in ruling out one potential source of systematic error to ensure the accuracy of analysis.

  2. Direct gravimetric determination of aerosol mass concentration in central antarctica.

    Science.gov (United States)

    Annibaldi, Anna; Truzzi, Cristina; Illuminati, Silvia; Scarponi, Giuseppe

    2011-01-01

    In Antarctica, experimental difficulties due to extreme conditions have meant that aerosol mass has rarely been measured directly by gravimetry, and only in coastal areas where concentrations were in the range of 1-7 μg m(-3). The present work reports on a careful differential weighing methodology carried out for the first time on the plateau of central Antarctica (Dome C, East Antarctica). To solve problems of accurate aerosol mass measurements, a climatic room was used for conditioning and weighing filters. Measurements were carried out in long stages of several hours of readings with automatic recording of temperature/humidity and mass. This experimental scheme allowed us to sample from all the measurements (up to 2000) carried out before and after exposure, those which were recorded under the most stable humidity conditions and, even more importantly, as close to each other as possible. The automatic reading of the mass allowed us in any case to obtain hundreds of measurements from which to calculate average values with uncertainties sufficiently low to meet the requirements of the differential weighing procedure (±0.2 mg in filter weighing, between ±7% and ±16% both in aerosol mass and concentration measurements). The results show that the average summer aerosol mass concentration (aerodynamic size ≤10 μm) in central Antarctica is about 0.1 μg m(-3), i.e., about 1/10 of that of coastal Antarctic areas. The concentration increases by about 4-5 times at a site very close to the station.

  3. A reproducible method to determine the meteoroid mass index

    CERN Document Server

    Pokorny, Petr

    2016-01-01

    Context. The determination of meteoroid mass indices is central to flux measurements and evolutionary studies of meteoroid populations. However, different authors use different approaches to fit observed data, making results difficult to reproduce and the resulting uncertainties difficult to justify. The real, physical, uncertainties are usually an order of magnitude higher than the reported values. Aims. We aim to develop a fully automated method that will measure meteoroid mass indices and associated uncertainty. We validate our method on large radar and optical datasets and compare results to obtain a best estimate of the true meteoroid mass index. Methods. Using MultiNest, a Bayesian inference tool that calculates the evidence and explores the parameter space, we search for the best fit of cumulative number vs. mass distributions in a four-dimensional space of variables ($a,b,X_1,X_2$). We explore biases in meteor echo distributions using optical meteor data as a calibration dataset to establish the syste...

  4. Determining gaseous composition of fluid inclusions with quadrupole mass spectrometer

    Institute of Scientific and Technical Information of China (English)

    朱和平; 王莉娟

    2002-01-01

    Quadrupole mass spectrometer (QMS) is an instrument for effectively determining gaseous composition of fluid inclusion. The gaseous component is extracted from inclusions with thermal decrepitation method and then determined with the sensitive QMS instrument. The method is characterized by high sensitivity and high accuracy with the relative standard deviation (RSD, n = 6) of less than 3%. It has been successfully used for analyzing fluid inclusions. The analytical re-sults meet the requirement of geological study.

  5. A composite score combining waist circumference and body mass index more accurately predicts body fat percentage in 6-to 13-year-old children

    NARCIS (Netherlands)

    Aeberli, I.; Gut-Knabenhans, M.; Kusche-Ammann, R.S.; Molinari, L.; Zimmermann, M.B.

    2013-01-01

    Body mass index (BMI) and waist circumference (WC) are widely used to predict % body fat (BF) and classify degrees of pediatric adiposity. However, both measures have limitations. The aim of this study was to evaluate whether a combination of WC and BMI would more accurately predict %BF than either

  6. CASD-NMR 2: robust and accurate unsupervised analysis of raw NOESY spectra and protein structure determination with UNIO

    Energy Technology Data Exchange (ETDEWEB)

    Guerry, Paul; Duong, Viet Dung; Herrmann, Torsten, E-mail: torsten.herrmann@ens-lyon.fr [Université de Lyon (UMR 5280 CNRS, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1), Institut des Sciences Analytiques, Centre de RMN à très Hauts Champs (France)

    2015-08-15

    UNIO is a comprehensive software suite for protein NMR structure determination that enables full automation of all NMR data analysis steps involved—including signal identification in NMR spectra, sequence-specific backbone and side-chain resonance assignment, NOE assignment and structure calculation. Within the framework of the second round of the community-wide stringent blind NMR structure determination challenge (CASD-NMR 2), we participated in two categories of CASD-NMR 2, namely using either raw NMR spectra or unrefined NOE peak lists as input. A total of 15 resulting NMR structure bundles were submitted for 9 out of 10 blind protein targets. All submitted UNIO structures accurately coincided with the corresponding blind targets as documented by an average backbone root mean-square deviation to the reference proteins of only 1.2 Å. Also, the precision of the UNIO structure bundles was virtually identical to the ensemble of reference structures. By assessing the quality of all UNIO structures submitted to the two categories, we find throughout that only the UNIO–ATNOS/CANDID approach using raw NMR spectra consistently yielded structure bundles of high quality for direct deposition in the Protein Data Bank. In conclusion, the results obtained in CASD-NMR 2 are another vital proof for robust, accurate and unsupervised NMR data analysis by UNIO for real-world applications.

  7. A reproducible method to determine the meteoroid mass index

    Science.gov (United States)

    Pokorný, P.; Brown, P. G.

    2016-08-01

    Context. The determination of meteoroid mass indices is central to flux measurements and evolutionary studies of meteoroid populations. However, different authors use different approaches to fit observed data, making results difficult to reproduce and the resulting uncertainties difficult to justify. The real, physical, uncertainties are usually an order of magnitude higher than the reported values. Aims: We aim to develop a fully automated method that will measure meteoroid mass indices and associated uncertainty. We validate our method on large radar and optical datasets and compare results to obtain a best estimate of the true meteoroid mass index. Methods: Using MultiNest, a Bayesian inference tool that calculates the evidence and explores the parameter space, we search for the best fit of cumulative number vs. mass distributions in a four-dimensional space of variables (a,b,X1,X2). We explore biases in meteor echo distributions using optical meteor data as a calibration dataset to establish the systematic offset in measured mass index values. Results: Our best estimate for the average de-biased mass index for the sporadic meteoroid complex, as measured by radar appropriate to the mass range 10-3 > m > 10-5 g, was s = -2.10 ± 0.08. Optical data in the 10-1 > m > 10-3 g range, with the shower meteors removed, produced s = -2.08 ± 0.08. We find the mass index used by Grün et al. (1985) is substantially larger than we measure in the 10-4 manual and a sample dataset can be found here: http://ftp://aquarid.physics.uwo.ca/pub/peter/MassIndexCode/

  8. Two-dimensional flow nanometry of biological nanoparticles for accurate determination of their size and emission intensity

    Science.gov (United States)

    Block, Stephan; Fast, Björn Johansson; Lundgren, Anders; Zhdanov, Vladimir P.; Höök, Fredrik

    2016-01-01

    Biological nanoparticles (BNPs) are of high interest due to their key role in various biological processes and use as biomarkers. BNP size and composition are decisive for their functions, but simultaneous determination of both properties with high accuracy remains challenging. Optical microscopy allows precise determination of fluorescence/scattering intensity, but not the size of individual BNPs. The latter is better determined by tracking their random motion in bulk, but the limited illumination volume for tracking this motion impedes reliable intensity determination. Here, we show that by attaching BNPs to a supported lipid bilayer, subjecting them to hydrodynamic flows and tracking their motion via surface-sensitive optical imaging enable determination of their diffusion coefficients and flow-induced drifts, from which accurate quantification of both BNP size and emission intensity can be made. For vesicles, the accuracy of this approach is demonstrated by resolving the expected radius-squared dependence of their fluorescence intensity for radii down to 15 nm. PMID:27658367

  9. Charm quark mass determined from a pair of sum rules

    CERN Document Server

    Erler, Jens; Spiesberger, Hubert

    2016-01-01

    In this paper, we present preliminary results of the determination of the charm quark mass $\\hat{m}_c$ from QCD sum rules of moments of the vector current correlator calculated in perturbative QCD at ${\\cal O} (\\hat \\alpha_s^3)$. Self-consistency between two different sum rules allow to determine the continuum contribution to the moments without requiring experimental input, except for the charm resonances below the continuum threshold. The existing experimental data from the continuum region is used, then, to confront the theoretical determination and reassess the theoretic uncertainty.

  10. Mass of Asteroid (25143) Itokawa Determined by Hayabusa Spacecraft

    Science.gov (United States)

    Yoshikawa, M.; Itokawa Mass Determination Team

    Hayabusa MUSES-C is the asteroid sample return mission of Japan It was launched on May 9 2003 and it arrived at its destination Asteroid 25143 Itokawa on September 12 2005 For about three months Hayabusa made detailed observations of Itokawa and tried to touch down on its surface twice after several rehearsal approaches In this mission period Hayabusa was under the effect of gravity attraction of Itokawa In this paper we report about the mass determination of Itokawa At first Hayabusa stayed around the position of 20 km from Itokawa and then it moved a little closer about 7 km from Itokawa Using the range and Doppler data from Sept 12 to Oct 2 the mass of Itokawa was estimated as 3 51 x 10 10 kg Since the effect of the solar radiation pressure is much larger than that of the gravitational attraction from Itokawa at this time the error of this estimation is about 15 We expected that we could get more precise value of the mass when Hayabusa approached much closer to Itokawa However one of the two reaction wheels had a trouble and after Oct 3 the attitude control was done by the chemical thrusters The chemical thrusters generated small orbital acceleration so it became difficult to carry out the precise mass determination of Itokawa Therefore we intentionally stopped the attitude maneuvers on Oct 21-22 when distance from Itokawa is about 3 km On this pass we tried to determine the mass of Itokawa and we got the value of 3 43 x 10 10 kg with the error of 5 Up to this analysis we assume a point mass model

  11. High-Precision Direct Mass Determination of Unstable Isotopes

    CERN Multimedia

    2002-01-01

    The extension of systematic high-precision measurements of the nuclear mass to nuclei far from the valley of $\\beta$ stability is of great interest in nuclear physics and astrophysics. The mass, or binding energy, is a fundamental gross property and a key input parameter for nuclear matter calculations. It is also a sensitive probe for collective and single-particle effects in nuclear structure. \\\\ \\\\ For such purposes, nuclear masses need to be known to an accuracy of about 10$^{-7}$ (i.e. $\\Delta$M~$\\leq$~10~keV for A~=~100). To resolve a particular mass from its nuclear isomers and isobars, resolving power of 10$^6$ are often required. To achieve this, the ions delivered by the on-line mass separator ISOLDE are confined in a Penning quadrupole trap. This trap is placed in the very homogeneous and stable magnetic field of a superconducting magnet. Here, the cyclotron frequency and hence the mass are determined. \\\\ \\\\ The first measurements using this new technique have been completed for a long chain of Cs ...

  12. Saponification reaction system: a detailed mass transfer coefficient determination.

    Science.gov (United States)

    Pečar, Darja; Goršek, Andreja

    2015-01-01

    The saponification of an aromatic ester with an aqueous sodium hydroxide was studied within a heterogeneous reaction medium in order to determine the overall kinetics of the selected system. The extended thermo-kinetic model was developed compared to the previously used simple one. The reaction rate within a heterogeneous liquid-liquid system incorporates a chemical kinetics term as well as mass transfer between both phases. Chemical rate constant was obtained from experiments within a homogeneous medium, whilst the mass-transfer coefficient was determined separately. The measured thermal profiles were then the bases for determining the overall reaction-rate. This study presents the development of an extended kinetic model for considering mass transfer regarding the saponification of ethyl benzoate with sodium hydroxide within a heterogeneous reaction medium. The time-dependences are presented for the mass transfer coefficient and the interfacial areas at different heterogeneous stages and temperatures. The results indicated an important role of reliable kinetic model, as significant difference in k(L)a product was obtained with extended and simple approach.

  13. Biases on initial mass function determinations. III. Cluster masses derived from unresolved photometry

    CERN Document Server

    Apellániz, J Maíz

    2009-01-01

    It is currently common to use spatially unresolved multi-filter broad-band photometry to determine the masses of individual stellar clusters (and hence the cluster mass function, CMF). I analyze the stochastic effects introduced by the sampling of the stellar initial mass function (SIMF) in the derivation of the individual masses and the CMF and I establish that such effects are the largest contributor to the observational uncertainties. An analytical solution, valid in the limit where uncertainties are small, is provided to establish the range of cluster masses over which the CMF slope can be obtained with a given accuracy. The validity of the analytical solution is extended to higher mass uncertainties using Monte Carlo simulations and the Gamma approximation. The value of the Poisson mass is calculated for a large range of ages and a variety of filters for solar-metallicity clusters measured with single-filter photometry. A method that uses the code CHORIZOS is presented to simultaneously derive masses, ag...

  14. Accurate retention time determination of co-eluting proteins in analytical chromatography by means of spectral data.

    Science.gov (United States)

    Dismer, Florian; Hansen, Sigrid; Oelmeier, Stefan Alexander; Hubbuch, Jürgen

    2013-03-01

    Chromatography is the method of choice for the separation of proteins, at both analytical and preparative scale. Orthogonal purification strategies for industrial use can easily be implemented by combining different modes of adsorption. Nevertheless, with flexibility comes the freedom of choice and optimal conditions for consecutive steps need to be identified in a robust and reproducible fashion. One way to address this issue is the use of mathematical models that allow for an in silico process optimization. Although this has been shown to work, model parameter estimation for complex feedstocks becomes the bottleneck in process development. An integral part of parameter assessment is the accurate measurement of retention times in a series of isocratic or gradient elution experiments. As high-resolution analytics that can differentiate between proteins are often not readily available, pure protein is mandatory for parameter determination. In this work, we present an approach that has the potential to solve this problem. Based on the uniqueness of UV absorption spectra of proteins, we were able to accurately measure retention times in systems of up to four co-eluting compounds. The presented approach is calibration-free, meaning that prior knowledge of pure component absorption spectra is not required. Actually, pure protein spectra can be determined from co-eluting proteins as part of the methodology. The approach was tested for size-exclusion chromatograms of 38 mixtures of co-eluting proteins. Retention times were determined with an average error of 0.6 s (1.6% of average peak width), approximated and measured pure component spectra showed an average coefficient of correlation of 0.992.

  15. Determination of the globular cluster and halo stellar mass functions and stellar and brown dwarf densities

    CERN Document Server

    Chabrier, G; Chabrier, Gilles; Méra, Dominique

    1997-01-01

    We use recent low-mass star models, which reproduce accurately the observed sequences of various globular clusters, to convert the observed luminosity functions into bolometric luminosity functions and mass functions down to the bottom of the main sequence. These mass functions are well describedby a slowly rising power-law $dN/dm\\propto m^{-\\alpha}$, with $0.5\\wig < \\alpha \\wig < 1.5$, down to $\\sim 0.1 \\msol$, independently of the metallicity, suggesting a rather universal behaviour of the cluster initial mass functions. We predict luminosity functions in the NICMOS filters in the stellar and in the brown dwarf domains for different mass functions and metallicities. We apply these calculations to the determination, slope and normalization, of the mass function of the Galactic halo (spheroid and dark halo). The spheroid mass function is well described by the afore-mentioned power-law function with function below $\\sim 0.15 \\msol$ can not be excluded with the data presently available. Comparison with th...

  16. Continuation of Mass determinations through a Double Focusing Mass Spectrometer on Line with ISOLDE

    CERN Multimedia

    2002-01-01

    In a previous experiment (1976-77) we have demonstrated the interest and feasibility of atomic mass determinations from the direct measurements of mass ratios on Rb, Cs and Fr isotopes. Masses of long series of isotopes on both side of stability were determined with an accuracy of a few tens to 300 keV (for th exotic). Interesting nuclear structure features could be observed as for example the indication for an onset of deformation, at N~=~60 for Z~=~37, which stimulated further experiments and theoretical calculations. The many mass values, until then unknown, we obtained in our experiments, gave in addition the possibility to make detailed tests of the nuclear mass predictions. Due to improvements on our mass spectrometer (better transmission and higher resolving power) and increased ISOLDE production yields, some new and valuable measurements can be performed. We plan: \\item a) to continue the measurements towards even heavier isotopes and explore the deformation regions which start at |9|7Rb and |1|4|6Cs;...

  17. Accurate determination of genetic identity for a single cacao bean, using molecular markers with a nanofluidic system, ensures cocoa authentication.

    Science.gov (United States)

    Fang, Wanping; Meinhardt, Lyndel W; Mischke, Sue; Bellato, Cláudia M; Motilal, Lambert; Zhang, Dapeng

    2014-01-15

    Cacao (Theobroma cacao L.), the source of cocoa, is an economically important tropical crop. One problem with the premium cacao market is contamination with off-types adulterating raw premium material. Accurate determination of the genetic identity of single cacao beans is essential for ensuring cocoa authentication. Using nanofluidic single nucleotide polymorphism (SNP) genotyping with 48 SNP markers, we generated SNP fingerprints for small quantities of DNA extracted from the seed coat of single cacao beans. On the basis of the SNP profiles, we identified an assumed adulterant variety, which was unambiguously distinguished from the authentic beans by multilocus matching. Assignment tests based on both Bayesian clustering analysis and allele frequency clearly separated all 30 authentic samples from the non-authentic samples. Distance-based principle coordinate analysis further supported these results. The nanofluidic SNP protocol, together with forensic statistical tools, is sufficiently robust to establish authentication and to verify gourmet cacao varieties. This method shows significant potential for practical application.

  18. Staphylococcus aureus interaction with phospholipid vesicles--a new method to accurately determine accessory gene regulator (agr activity.

    Directory of Open Access Journals (Sweden)

    Maisem Laabei

    Full Text Available The staphylococcal accessory gene regulatory (agr operon is a well-characterised global regulatory element that is important in the control of virulence gene expression for Staphylococcus aureus, a major human pathogen. Hence, accurate and sensitive measurement of Agr activity is central in understanding the virulence potential of Staphylococcus aureus, especially in the context of Agr dysfunction, which has been linked with persistent bacteraemia and reduced susceptibility to glycopeptide antibiotics. Agr function is typically measured using a synergistic haemolysis CAMP assay, which is believe to report on the level of expression of one of the translated products of the agr locus, delta toxin. In this study we develop a vesicle lysis test (VLT that is specific to small amphipathic peptides, most notably delta and Phenol Soluble Modulin (PSM toxins. To determine the accuracy of this VLT method in assaying Agr activity, we compared it to the CAMP assay using 89 clinical Staphylococcus aureus isolates. Of the 89 isolates, 16 were designated as having dysfunctional Agr systems by the CAMP assay, whereas only three were designated as such by VLT. Molecular analysis demonstrated that of these 16 isolates, the 13 designated as having a functional Agr system by VLT transcribed rnaIII and secreted delta toxin, demonstrating they have a functional Agr system despite the results of the CAMP assay. The agr locus of all 16 isolates was sequenced, and only the 3 designated as having a dysfunctional Agr system contained mutations, explaining their Agr dysfunction. Given the potentially important link between Agr dysfunction and clinical outcome, we have developed an assay that determines this more accurately than the conventional CAMP assay.

  19. An accurate determination of the triple point temperature of pure {sup 20}Ne and {sup 22}Ne

    Energy Technology Data Exchange (ETDEWEB)

    Pavese, F., E-mail: f.pavese@inrim.i [Istituto Nazionale di Ricerca Metrologica (INRIM), strada delle Cacce 91, 1035 Torino (Italy); Valkiers, S., E-mail: staf.valkiers@ec.europa.e [Institute of Reference Materials and Measurements (IRMM), Steenweg naar Retie 111, 2440 Geel (Belgium); Steur, P.P.M., E-mail: p.steur@inrim.i [Istituto Nazionale di Ricerca Metrologica (INRIM), strada delle Cacce 91, 1035 Torino (Italy); Ferri, D.; Giraudi, D. [Istituto Nazionale di Ricerca Metrologica (INRIM), strada delle Cacce 91, 1035 Torino (Italy)

    2010-10-15

    The paper reports on new determinations at INRIM of the triple point temperature of pure neon isotopes {sup 20}Ne and {sup 22}Ne, obtained on samples sealed in cryogenic cells and measured with an uncertainty much lower than that of the previous determinations. The experimental technique is the same used at INRIM for recent studies on neon of natural-isotopic composition, showing an expanded uncertainty of {approx}30 {mu}K for a single cell and {approx}50 {mu}K for the comparison of sample pairs. The determinations were mainly intended to obtain a more accurate value of the temperature difference for the two pure isotopes, found to be 0.14660 K with an expanded uncertainty of 0.00007 K. The temperature values were found to be 24.5422 K for {sup 20}Ne and 24.6888 K for {sup 22}Ne on ITS-90, but each with a larger expanded uncertainty, 0.00032 K. This is mainly caused, contrarily to the difference, by each of these values being affected by the present ambiguity of the ITS-90 definition. This definition refers to neon generically to 'natural' composition, while its uncorrected variability heavily affects the uncertainty of the thermometer calibrations. These results for pure isotopes are compared with those recently obtained at INRIM on samples of commercial neon of natural composition and with literature data. The problems involved in the correction for the residual content of isotopic impurities and for chemical impurities are discussed.

  20. Simple and accurate determination of global tau(R) in proteins using (13)C or (15)N relaxation data.

    Science.gov (United States)

    Mispelter, J; Izadi-Pruneyre, N; Quiniou, E; Adjadj, E

    2000-03-01

    In the study of protein dynamics by (13)C or (15)N relaxation measurements different models from the Lipari-Szabo formalism are used in order to determine the motion parameters. The global rotational correlation time tau(R) of the molecule must be estimated prior to the analysis. In this Communication, the authors propose a new approach in determining an accurate value for tau(R) in order to realize the best fit of R(2) for the whole sequence of the protein, regardless of the different type of motions atoms may experience. The method first determines the highly structured regions of the sequence. For each corresponding site, the Lipari-Szabo parameters are calculated for R(1) and NOE, using an arbitrary value for tau(R). The chi(2) for R(2), summed over the selected sites, shows a clear minimum, as a function of tau(R). This minimum is used to better estimate a proper value for tau(R).

  1. Asteroid Perturbations and Mass Determination for the ASTROD Space Mission

    CERN Document Server

    Tang, C J; Tang, Chien-Jen; Ni, Wei-Tou

    2004-01-01

    Due to the high-precision nature of the ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) mission concept, the asteroid perturbations on the ASTROD spacecraft is crucial. These perturbations need to be modelled and determined together with relativistic effects and other solar-system parameters. In a previous investigation (Su et al., Planetary and Space Science, 47, 339-43[1999]), we used the mass estimation of Ceres, Pallas and Vesta in the literature to calculate their perturbations on the ASTROD spacecraft. Recently, we established an ephemeris framework (CGC 1) including the 3 big asteroids and used this ephemeris framework to simulate the determination of their masses together with other solar-system parameters and relativistic-gravity parameters. In this paper, we extend the CGC 1 to CGC 2 ephemeris framework to include 492 asteroids (with diameter > 65 km) . We then use CGC 2 to simulate the determination of ten parameters -- the masses of Ceres, Pallas and Vesta, the six average d...

  2. HEASARC Astronomical Archive: GLIESE2MAS - Gliese Catalog Stars with Accurate Coordinates and 2MASS Cross-Identifications

    Data.gov (United States)

    National Aeronautics and Space Administration — This table contains precise epoch 2000 coordinates and cross-identifications to sources in the 2MASS Point Source Catalog for nearly all stars in the Gliese,...

  3. Accurate Determination of Glacier Surface Velocity Fields with a DEM-Assisted Pixel-Tracking Technique from SAR Imagery

    Directory of Open Access Journals (Sweden)

    Shiyong Yan

    2015-08-01

    Full Text Available We obtained accurate, detailed motion distribution of glaciers in Central Asia by applying digital elevation model (DEM assisted pixel-tracking method to L-band synthetic aperture radar imagery. The paper firstly introduces and analyzes each component of the offset field briefly, and then describes the method used to efficiently and precisely compensate the topography-related offset caused by the large spatial baseline and rugged terrain with the help of DEM. The results indicate that the rugged topography not only forms the complex shapes of glaciers, but also affects the glacier velocity estimation, especially with large spatial baseline. The maximum velocity, 0.85 m∙d−1, was observed in the middle part on the Fedchenko Glacier, which is the world’s longest mountain glacier. The motion fluctuation on its main trunk is apparently influenced by mass flowing in from tributaries, as well as angles between tributaries and the main stream. The approach presented in this paper was proved to be highly appropriate for monitoring glacier motion and will provide valuable sensitive indicators of current and future climate change for environmental analysis.

  4. Determining the mass of Didymos' secondary by visual imaging

    Science.gov (United States)

    Grieger, Björn; Küppers, Michael

    2016-04-01

    A critical requirement for the Asteroid Impact Mission (AIM) is the ability to determine the mass of Didymos' secondary with an accuracy of about 10 %. On one hand, this is necessary in order to plan the delivery of the lander MASCOT-2 with sufficient precision, on the other hand, it is needed to estimate the momentum transfer by the impact of the DART spacecraft and hence to verify the concept of asteroid deflection. The conventional approach to estimate the mass of a solar system body through its gravitational effect by tracking the spacecraft trajectory is not viable for Didymos' secondary. With a diameter of only 163 m, its mass is too small to yield a significant impact on the spacecraft trajectory at reasonable fly-by distances. Instead, the idea to determine the mass of the secondary by measuring the "wobble" of the primary around the common centre of gravity has been put forward. The mass of the primary is about 100 times the mass of the secondary, thus the expected wobble radius is about one percent of the distance of 1180 m between the two, that is about 10 m. Such a wobble may be possible to measure either by means of using the optical communication device OPTEL-D as an altimeter or by direct observation with the visual imaging system VIS. Here, we investigate the latter approach. The idea is to identify landmarks in VIS images and to simultaneously solve for the positions of the landmarks and the spacecraft in the body fixed frame of the primary. The temporary evolution of the spacecraft position comprises three components: the drift of the spacecraft due to gravitational disturbance and solar radiation pressure (and errors in the knowledge of the initial state), the apparent motion of the spacecraft around the primary (in the body fixed frame) due to its rotation, an apparent oscillation of the spacecraft position due to the wobble of the primary with a known period. While the wobble component is quite small (about 10ṁ), its period is known and it is

  5. Accurate determinations of one-bond 13C-13C couplings in 13C-labeled carbohydrates.

    Science.gov (United States)

    Azurmendi, Hugo F; Freedberg, Darón I

    2013-03-01

    Carbon plays a central role in the molecular architecture of carbohydrates, yet the availability of accurate methods for (1)D(CC) determination has not been sufficiently explored, despite the importance that such data could play in structural studies of oligo- and polysaccharides. Existing methods require fitting intensity ratios of cross- to diagonal-peaks as a function of the constant-time (CT) in CT-COSY experiments, while other methods utilize measurement of peak separation. The former strategies suffer from complications due to peak overlap, primarily in regions close to the diagonal, while the latter strategies are negatively impacted by the common occurrence of strong coupling in sugars, which requires a reliable assessment of their influence in the context of RDC determination. We detail a (13)C-(13)C CT-COSY method that combines a variation in the CT processed with diagonal filtering to yield (1)J(CC) and RDCs. The strategy, which relies solely on cross-peak intensity modulation, is inspired in the cross-peak nulling method used for J(HH) determinations, but adapted and extended to applications where, like in sugars, large one-bond (13)C-(13)C couplings coexist with relatively small long-range couplings. Because diagonal peaks are not utilized, overlap problems are greatly alleviated. Thus, one-bond couplings can be determined from different cross-peaks as either active or passive coupling. This results in increased accuracy when more than one determination is available, and in more opportunities to measure a specific coupling in the presence of severe overlap. In addition, we evaluate the influence of strong couplings on the determination of RDCs by computer simulations. We show that individual scalar couplings are notably affected by the presence of strong couplings but, at least for the simple cases studied, the obtained RDC values for use in structural calculations were not, because the errors introduced by strong couplings for the isotropic and

  6. Accurate determinations of one-bond 13C-13C couplings in 13C-labeled carbohydrates

    Science.gov (United States)

    Azurmendi, Hugo F.; Freedberg, Darón I.

    2013-03-01

    Carbon plays a central role in the molecular architecture of carbohydrates, yet the availability of accurate methods for 1DCC determination has not been sufficiently explored, despite the importance that such data could play in structural studies of oligo- and polysaccharides. Existing methods require fitting intensity ratios of cross- to diagonal-peaks as a function of the constant-time (CT) in CT-COSY experiments, while other methods utilize measurement of peak separation. The former strategies suffer from complications due to peak overlap, primarily in regions close to the diagonal, while the latter strategies are negatively impacted by the common occurrence of strong coupling in sugars, which requires a reliable assessment of their influence in the context of RDC determination. We detail a 13C-13C CT-COSY method that combines a variation in the CT processed with diagonal filtering to yield 1JCC and RDCs. The strategy, which relies solely on cross-peak intensity modulation, is inspired in the cross-peak nulling method used for JHH determinations, but adapted and extended to applications where, like in sugars, large one-bond 13C-13C couplings coexist with relatively small long-range couplings. Because diagonal peaks are not utilized, overlap problems are greatly alleviated. Thus, one-bond couplings can be determined from different cross-peaks as either active or passive coupling. This results in increased accuracy when more than one determination is available, and in more opportunities to measure a specific coupling in the presence of severe overlap. In addition, we evaluate the influence of strong couplings on the determination of RDCs by computer simulations. We show that individual scalar couplings are notably affected by the presence of strong couplings but, at least for the simple cases studied, the obtained RDC values for use in structural calculations were not, because the errors introduced by strong couplings for the isotropic and oriented phases are very

  7. Non-targeted analysis of electronics waste by comprehensive two-dimensional gas chromatography combined with high-resolution mass spectrometry: Using accurate mass information and mass defect analysis to explore the data.

    Science.gov (United States)

    Ubukata, Masaaki; Jobst, Karl J; Reiner, Eric J; Reichenbach, Stephen E; Tao, Qingping; Hang, Jiliang; Wu, Zhanpin; Dane, A John; Cody, Robert B

    2015-05-22

    Comprehensive two-dimensional gas chromatography (GC×GC) and high-resolution mass spectrometry (HRMS) offer the best possible separation of their respective techniques. Recent commercialization of combined GC×GC-HRMS systems offers new possibilities for the analysis of complex mixtures. However, such experiments yield enormous data sets that require new informatics tools to facilitate the interpretation of the rich information content. This study reports on the analysis of dust obtained from an electronics recycling facility by using GC×GC in combination with a new high-resolution time-of-flight (TOF) mass spectrometer. New software tools for (non-traditional) Kendrick mass defect analysis were developed in this research and greatly aided in the identification of compounds containing chlorine and bromine, elements that feature in most persistent organic pollutants (POPs). In essence, the mass defect plot serves as a visual aid from which halogenated compounds are recognizable on the basis of their mass defect and isotope patterns. Mass chromatograms were generated based on specific ions identified in the plots as well as region of the plot predominantly occupied by halogenated contaminants. Tentative identification was aided by database searches, complementary electron-capture negative ionization experiments and elemental composition determinations from the exact mass data. These included known and emerging flame retardants, such as polybrominated diphenyl ethers (PBDEs), hexabromobenzene, tetrabromo bisphenol A and tris (1-chloro-2-propyl) phosphate (TCPP), as well as other legacy contaminants such as polychlorinated biphenyls (PCBs) and polychlorinated terphenyls (PCTs).

  8. Negative electrospray ionisation of fluorotelomer alcohols (FTOH) and FTOH-derived acrylate surfactants by liquid chromatography coupled to accurate (tandem) mass spectrometry

    DEFF Research Database (Denmark)

    Trier, Xenia; Christensen, Jan H.; Niessen, Wilfried M. A.

    Fluorotelomer alcohols (FTOHs) are used to synthesize fluorinated surfactants, which form bioaccumulative perfluorinated degradation products, which are toxic to humans and the environment. To facilitate screening for FTOH-derived surfactants by LC-ESI–-MS, we identified product ions of FTOHs, an......, and propose FTOH fragmentation pathways on two MS instruments. By extraction of FTOH basepeak ions from accurate mass spectra, homologues series of peaks showed up in an industrial blend of FTOH-derived fluoroacrylates used in food paper packaging....

  9. Biogenic aldehyde determination by reactive paper spray ionization mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bag, Soumabha; Hendricks, P.I. [Aston Labs, Department of Chemistry, Purdue University, West Lafayette, IN 47907 (United States); Reynolds, J.C. [Centre for Analytical Science, Loughborough University, Loughborough, Leicestershire (United Kingdom); Cooks, R.G., E-mail: cooks@purdue.edu [Aston Labs, Department of Chemistry, Purdue University, West Lafayette, IN 47907 (United States)

    2015-02-20

    Highlights: • In-situ derivatization and simultaneous ionization used to detect aldehydes. • Biogenic aliphatic and aromatic aldehydes reacted with 4-aminophenol. • Derivatized products yield structurally characteristic fragment ions. • This measurement demonstrated using a miniaturized portable mass spectrometer. - Abstract: Ionization of aliphatic and aromatic aldehydes is improved by performing simultaneous chemical derivatization using 4-aminophenol to produce charged iminium ions during paper spray ionization. Accelerated reactions occur in the microdroplets generated during the paper spray ionization event for the tested aldehydes (formaldehyde, n-pentanaldehyde, n-nonanaldehyde, n-decanaldehyde, n-dodecanaldehyde, benzaldehyde, m-anisaldehyde, and p-hydroxybenzaldehyde). Tandem mass spectrometric analysis of the iminium ions using collision-induced dissociation demonstrated that straight chain aldehydes give a characteristic fragment at m/z 122 (shown to correspond to protonated 4-(methyleneamino)phenol), while the aromatic aldehyde iminium ions fragment to give a characteristic product ion at m/z 120. These features allow straightforward identification of linear and aromatic aldehydes. Quantitative analysis of n-nonaldehyde using a benchtop mass spectrometer demonstrated a linear response over 3 orders of magnitude from 2.5 ng to 5 μg of aldehyde loaded on the filter paper emitter. The limit of detection was determined to be 2.2 ng for this aldehyde. The method had a precision of 22%, relative standard deviation. The experiment was also implemented using a portable ion trap mass spectrometer.

  10. Atomic spectroscopy and highly accurate measurement: determination of fundamental constants; Spectroscopie atomique et mesures de grande precision: determination de constantes fonfamentales

    Energy Technology Data Exchange (ETDEWEB)

    Schwob, C

    2006-12-15

    This document reviews the theoretical and experimental achievements of the author concerning highly accurate atomic spectroscopy applied for the determination of fundamental constants. A pure optical frequency measurement of the 2S-12D 2-photon transitions in atomic hydrogen and deuterium has been performed. The experimental setting-up is described as well as the data analysis. Optimized values for the Rydberg constant and Lamb shifts have been deduced (R = 109737.31568516 (84) cm{sup -1}). An experiment devoted to the determination of the fine structure constant with an aimed relative uncertainty of 10{sup -9} began in 1999. This experiment is based on the fact that Bloch oscillations in a frequency chirped optical lattice are a powerful tool to transfer coherently many photon momenta to the atoms. We have used this method to measure accurately the ratio h/m(Rb). The measured value of the fine structure constant is {alpha}{sub -1} = 137.03599884 (91) with a relative uncertainty of 6.7*10{sup -9}. The future and perspectives of this experiment are presented. This document presented before an academic board will allow his author to manage research work and particularly to tutor thesis students. (A.C.)

  11. Accurate and precise 40Ar/39Ar dating by high-resolution, multi-collection, mass spectrometry

    DEFF Research Database (Denmark)

    Storey, Michael; Rivera, Tiffany; Flude, Stephanie

    -Instruments multi-collector Noblesse noble gas mass spectrometer configured with a faraday detector and three ion-counting electron multipliers. The instrument has the capability to measure several noble gas isotopes simultaneously and to change measurement configurations instantaneously by the use of QUAD lenses...

  12. A note on the determination of light quark mass splitting

    CERN Document Server

    Deandrea, A; Talavera, P

    2008-01-01

    We provide a model-independent determination of the quantity B_0(m_d-m_u). Our approach rests only on chiral symmetry and data from the decay of the eta into three neutral pions. Since the low-energy prediction at next-to-leading order fails to reproduce the experimental results, we keep the strong interaction correction as an unknown parameter. As a first step, we relate this parameter to the quark mass difference using data from the Dalitz plot. A similar relation is obtained using data from the decay width. Combining both relations we obtain B_0(m_d-m_u)=(4495 +/- 440) MeV^2. We use the preceding value to estimate the size of the violation of Dashen's theorem and the quark mass ratio m_u/m_d.

  13. Accurate mass measurements for the confirmation of Sudan azo-dyes in hot chilli products by capillary liquid chromatography-electrospray tandem quadrupole orthogonal-acceleration time of flight mass spectrometry.

    Science.gov (United States)

    Calbiani, F; Careri, M; Elviri, L; Mangia, A; Zagnoni, I

    2004-11-26

    The potential of capillary liquid chromatography (microLC)-quadrupole/time-of-flight mass spectrometry (Q-TOF MS) for the confirmation of Sudan I, II, III and IV azo-dyes as contaminants in hot-chilli food products was demonstrated. Using the microLC-electrospray ionization (ESI)-Q-TOF MS technique, accurate mass measurements of Sudan dyes were performed both on standard solutions and on matrices. Precision of exact mass measurements was calculated taking into account the ion statistics according to the number of ion sampled in the measurement. Accurate mass measurements by MS/MS experiments were performed to elucidate azo-dye fragmentation patterns. Selectivity of the microLC-Q-TOF MS method was assessed by evaluating matrix suppression effects by pre-column injection of blank hot chilli tomato sauce matrices. The results were compared with those obtained on a LC-triple quadrupole-MS system. Confirmation of Sudan I present in hot chill tomato sauce samples was obtained by accurate mass measurements. In real samples trueness of exact mass measurements was estimated to be 1.6 and 4.4 ppm when calculated for hot chilli tomato sauce and hot chilli tomato with cheese sauce samples, respectively; precision was calculated around 9.5 ppm.

  14. A MASSIF Effort To Determine The Mass-Luminosity Relation for Stars of Various Ages, Metallicities, and Evolution States

    Science.gov (United States)

    Henry, Todd J.; Beedict, G. Fritz; Gies, Douglas R.; Golimowski, David A.; Ianna, Philip A.; Mason, Brian; McArthur, Barbara; Nelan, Edmund; Torres, Guillermo

    2004-01-01

    The MASSIF (Masses and Stellar Systems with Interferometry) Team will use SIM to investigate the mass content of the Galaxy - from huge stars to barely glimmering brown dwarfs, and from hot white dwarfs to exotic black holes. We will target various samples of the Galactic population to determine and relate the fundamental characteristics of mass, luminosity, age, composition, and multiplicity - attributes that together yield an extensive understanding of the stars. Our samples will include distant clusters that span a factor of 5000 in age, and commonplace stars and substellar objects that lurk near the Sun. The principal goals of the MASSIF Key Project are to (1) define the mass-luminosity relation for main sequence stars in five fundamental clusters so that effects of age and metallicity can be mapped (Trapezium, TW Hydrae, Pleiades, Hyades, and M67), and (2) determine accurate masses for representative examples of nearly every type of star, stellar descendant or brown dwarf in the Galaxy.

  15. Automatic Determination of the Conic Coronal Mass Ejection Model Parameters

    Science.gov (United States)

    Pulkkinen, A.; Oates, T.; Taktakishvili, A.

    2009-01-01

    Characterization of the three-dimensional structure of solar transients using incomplete plane of sky data is a difficult problem whose solutions have potential for societal benefit in terms of space weather applications. In this paper transients are characterized in three dimensions by means of conic coronal mass ejection (CME) approximation. A novel method for the automatic determination of cone model parameters from observed halo CMEs is introduced. The method uses both standard image processing techniques to extract the CME mass from white-light coronagraph images and a novel inversion routine providing the final cone parameters. A bootstrap technique is used to provide model parameter distributions. When combined with heliospheric modeling, the cone model parameter distributions will provide direct means for ensemble predictions of transient propagation in the heliosphere. An initial validation of the automatic method is carried by comparison to manually determined cone model parameters. It is shown using 14 halo CME events that there is reasonable agreement, especially between the heliocentric locations of the cones derived with the two methods. It is argued that both the heliocentric locations and the opening half-angles of the automatically determined cones may be more realistic than those obtained from the manual analysis

  16. Determination of Trace Elements in High Purity Gold by High Resolution Inductively Coupled Plasma Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    XIE Hualin; HUANG Kelong; NIE Xidu; FU Liang

    2009-01-01

    Trace elements were determined in high purity gold by high resolution inductively coupled plasma mass spectrometry(HR-ICP-MS).Sample were decomposed by aqua regia.To overcome some potentially problematic spectral interference,measurements were acquired in both medium and high resolution modes.The matrix effects due to the presence of excessive HCl and Au were evaluated.The optimum conditions for the determination was tested and discussed.The standard addition method was employed for quantitative analysis.The detection limits range from 0.01 μg/g to 0.28 μg/g depending on the elements.The method is accurate,quick and convenient.It has been applied to the determination of trace elements in high purity gold with satisfactory results.

  17. A direct method for determining the mass of gases in ICF shell

    Institute of Scientific and Technical Information of China (English)

    杨传路; 朱正和; 汪蓉; 谭明亮; 蒋刚; 王明达; 郑永铭; 唐永建; 郑志坚; 赵永宽

    2002-01-01

    In the present paper, the defects of dew point method for measuring the mass of gas filled in ICF shells are analyzed. An accurate state equation for gas D2 is deduced from Benedict-Webb-Rubin (BWR) equation and experimental data in planar phase. A direct method to determine gas mass in ICF shells via measuring the temperature and pressure outside the shells and solving the equation of state by numerical method is proposed. It overcomes the theoretical defects of dew point method and the complexities of equipment. In the present method, the state equation can be improved by more accurately measuring P-V-T values of gas D2, so the measuring precision of the mass of gas in the shells can also be improved. The present method is effective for treating mix gases filled in the shells as well. The errors between the computational results and experimental data are very small. Some cases in the filling process are predicted, and the proper temperature and pressure for filling gases effectively are also suggested.

  18. Precision charmonium and D physics from lattice QCD and determination of the charm quark mass

    CERN Document Server

    Davies, C T H

    2008-01-01

    I will describe recent results from the HPQCD collaboration using a new very accurate method for charm quarks in lattice QCD, that we have used in calculations including the full effect of u, d and s sea quarks. Multiple values of the lattice spacing and of the u, d and s sea quark masses allow us to extrapolate reliably, with a full error budget, to the real world. This opens up the field of charm physics to precision lattice QCD tests. So far we have calculated the D and D_s meson masses to 6 MeV, having fixed the charm quark mass from the eta_c meson. Our D and D_s decay constants (determined to 2%) make an interesting comparison to CLEO-c results as we await improved experimental errors. We are also able to determine the charm quark mass to an accuracy of 1% using charmonium correlators and high-order continuum QCD perturbation theory. Future calculations are briefly discussed.

  19. CLASH-VLT: Constraints on the Dark Matter Equation of State from Accurate Measurements of Galaxy Cluster Mass Profiles

    CERN Document Server

    Sartoris, Barbara; Rosati, Piero; Borgani, Stefano; Umetsu, Keiichi; Bartelmann, Matthias; Girardi, Marisa; Grillo, Claudio; Lemze, Doron; Zitrin, Adi; Balestra, Italo; Mercurio, Amata; Nonino, Mario; Postman, Marc; Czakon, Nicole; Bradley, Larry; Broadhurst, Tom; Coe, Dan; Medezinski, Elinor; Melchior, Peter; Meneghetti, Massimo; Merten, Julian; Annunziatella, Marianna; Benitez, Narciso; Czoske, Oliver; Donahue, Megan; Ettori, Stefano; Ford, Holland; Fritz, Alexander; Kelson, Dan; Koekemoer, Anton; Kuchner, Ulrike; Lombardi, Marco; Maier, Christian; Mou, Leonidas A; Munari, Emiliano; Presotto, Valentina; Scodeggio, Marco; Seitz, Stella; Tozzi, Paolo; Zheng, Wei; Ziegler, Bodo

    2014-01-01

    A pressureless scenario for the Dark Matter (DM) fluid is a widely adopted hypothesis, despite the absence of a direct observational evidence. According to general relativity, the total mass-energy content of a system shapes the gravitational potential well, but different test particles perceive this potential in different ways depending on their properties. Cluster galaxy velocities, being $\\ll$c, depend solely on the gravitational potential, whereas photon trajectories reflect the contributions from the gravitational potential plus a relativistic-pressure term that depends on the cluster mass. We exploit this phenomenon to constrain the Equation of State (EoS) parameter of the fluid, primarily DM, contained in galaxy clusters. We use the complementary information provided by the kinematic and lensing mass profiles of the galaxy cluster MACS 1206.2-0847 at $z=0.44$, as obtained in an extensive imaging and spectroscopic campaign within the CLASH survey. The unprecedented high quality of our data-set and the p...

  20. Direct determination of the atomic mass difference of Re187 and Os187 for neutrino physics and cosmochronology

    CERN Document Server

    Nesterenko, D A; Blaum, K; Block, M; Chenmarev, S; Doerr, A; Droese, C; Filianin, P E; Goncharov, M; Ramirez, E Minaya; Novikov, Yu N; Schweikhard, L; Simon, V V

    2016-01-01

    For the first time a direct determination of the atomic mass difference of 187Re and 187Os has been performed with the Penning-trap mass spectrometer SHIPTRAP applying the novel phase-imaging ion-cyclotron-resonance technique. The obtained value of 2492(30stat)(15sys) eV is in excellent agreement with the Q values determined indirectly with microcalorimetry and thus resolves a long-standing discrepancy with older proportional counter measurements. This is essential for the determination of the neutrino mass from the beta-decay of 187Re as planned in future microcalorimetric measurements. In addition, an accurate mass difference of 187Re and 187Os is also important for the assessment of 187Re for cosmochronology.

  1. Novel insight into neutrophil immune responses by dry mass determination of Candida albicans morphotypes.

    Directory of Open Access Journals (Sweden)

    Ava Hosseinzadeh

    Full Text Available The common fungal pathogen Candida albicans has the ability to grow as a yeast or as a hypha and can alternate between these morphotypes. The overall biomass of both morphotypes increases with growth. However, only yeasts, but not hyphae, exist as discrete cellular entities. Multiplicity of infection (MOI is a useful parameter to determine the initial inoculum of yeasts for in vitro infection assays. Since the amount of hyphae is difficult to quantify, comparable starting conditions in such assays cannot be determined accurately for yeasts and hyphae using MOI. To circumvent this problem, we have established a set of correlation coefficients to convert fungal metabolic activity and optical density to dry mass. Using these correlations, we were able to accurately compare ROS production and IL-8 release by polymorphonuclear neutrophils upon infection with equal dry mass amounts of yeast and hyphal morphotypes. Neutrophil responses depended on the initial form of infection, irrespective of C. albicans wild-type yeasts transforming to hyphal growth during the assay. Infection with a high mass of live C. albicans yeasts resulted in lower neutrophil ROS and this decrease stems from efficient ROS detoxification by C. albicans without directly affecting the phagocyte ROS machinery. Moreover, we show that dead C. albicans induces significantly less ROS and IL-8 release than live fungi, but thimerosal-killed C. albicans were still able to detoxify neutrophil ROS. Thus, the dry mass approach presented in this study reveals neutrophil responses to different amounts and morphotypes of C. albicans and serves as a template for studies that aim to identify morphotype-specific responses in a variety of immune cells.

  2. Caregiver's Country of Birth Is a Significant Determinant of Accurate Perception of Preschool-Age Children's Weight

    Science.gov (United States)

    Natale, Ruby; Uhlhorn, Susan B.; Lopez-Mitnik, Gabriela; Camejo, Stephanie; Englebert, Nicole; Delamater, Alan M.; Messiah, Sarah E.

    2016-01-01

    Background: One in four preschool-age children in the United States are currently overweight or obese. Previous studies have shown that caregivers of this age group often have difficulty accurately recognizing their child's weight status. The purpose of this study was to examine factors associated with accurate/inaccurate perception of child body…

  3. Determining protoplanetary disk gas masses from CO isotopologues line observations

    Science.gov (United States)

    Miotello, A.; van Dishoeck, E. F.; Kama, M.; Bruderer, S.

    2016-10-01

    Context. Despite intensive studies of protoplanetary disks, there is still no reliable way to determine their total (gast+dust) mass and their surface density distribution, quantities that are crucial for describing both the structure and the evolution of disks up to the formation of planets. Aims: The goal of this work is to use less-abundant CO isotopologues, such as 13CO, C18O and C17O, detection of which is routine for ALMA, to infer the gas mass of disks. Isotope-selective effects need to be taken into account in the analysis, because they can significantly modify CO isotopologues' line intensities. Methods: CO isotope-selective photodissociation has been implemented in the physical-chemical code DALI (Dust And LInes) and more than 800 disk models have been run for a range of disk and stellar parameters. Dust and gas temperature structures have been computed self-consistently, together with a chemical calculation of the main atomic and molecular species. Both disk structure and stellar parameters have been investigated by varying the parameters in the grid of models. Total fluxes have been ray-traced for different CO isotopologues and for various low J-transitions for different inclinations. Results: A combination of 13CO and C18O total intensities allows inference of the total disk mass, although with non-negligible uncertainties. These can be overcome by employing spatially resolved observations, that is the disk's radial extent and inclination. Comparison with parametric models shows differences at the level of a factor of a few, especially for extremely low and high disk masses. Finally, total line intensities for different CO isotopologue and for various low-J transitions are provided and are fitted to simple formulae. The effects of a lower gas-phase carbon abundance and different gas-to-dust ratios are investigated as well, and comparison with other tracers is made. Conclusions: Disk masses can be determined within a factor of a few by comparing CO

  4. Determining gaseous composition of fluid inclusions with quadrupole mass spectrometer

    Institute of Scientific and Technical Information of China (English)

    ZHU; Heping

    2002-01-01

    [1]Joseph, R. G., Stephen, E. K., Factors affecting gas analysis of inclusion fluid by quadrupole mass spectrometry, Geo-chimica et Acta, 1995, 59(19): 3977-3986.[2]Masakatsu, S., Takayuki, S., Naoto, T., Analysis of fluid inclusion gases from geothermal systems, using a rapid-scanning quadrupole mass spectrometer, Eur. J. Mineral., 1992, 4: 895-906.[3]Van den Kerkhof, A. M., Isochoric phase diagrams in the systems CO2-CH4 and CO2-N2: Application to fluid inclusions, Geochimica et Cosmochimica Acta, 1990, 54: 621-629.[4]Colin, B., Michael, P. S., Mass spectrometric determination of gases in individual fluid inclusions in natural minerals, Anal. Chem., 1986, 58: 1330-1333.[5]David, I. N., Fredrick, J. S., Analysis of volatiles in fluid inclusions by mass spectrometry, Chemical Geology, 1987, 61: 1-10.[6]Yoichi, M., Ryo, K., Takayuki, S. et al., Gas composition of fluid inclusion from the Mori Geothermal Reservoir, South-western Hokkaido, Japan, Resource Geology, 1997, 47(5): 283-291.[7]Lu Huanzhang, Guo Dijiang, Progress and trends of researches on fluid inclusions, Geological Review, 2000, 46(4): 385-392.[8]Xia Xinyu, Wang Xianbin, Chen Jiangfeng, Geningjie, composition of fluid inclusions and CO2 carbon isotope of ultra-high pressure metamorphic rocks in Shuanghe area, Dabieshan Mountain, Science in China (in Chinese), Ser. D, 1999, 29(4): 314-320.

  5. Accurate measurement of air supply. Radial blower with a mass flow sensor; Fuer eine exakte Luftzuteilung. Radialgeblaese mit Massenstromsensor

    Energy Technology Data Exchange (ETDEWEB)

    Hartauer, Siegbert [ebm-papst Landshut GmbH, Landshut (Germany)

    2009-07-01

    Fire is alive, which has always made it an interesting object for interior decoration, e.g. open chimneys or chimneys with glass windows. Modern gas-fuelled chimneys combine the soothing vision of open flames with efficient room heating. For low pollution and low consumption, fire needs fuel and oxygen in an optimum ratio. Conventional ''atmospheric'' burners must be adjusted on site, but variations of temperature and atmospheric pressure will still vary the air supply. As an optimum alternative, the contribution presents a new radial blower with an integrated mass flow sensor. (orig.)

  6. Image resolution influence on determination of resin injection rock mass

    Science.gov (United States)

    Wang, Weixing; Hakami, Eva

    2006-01-01

    In the context of nuclear waste repositories, an important approach to understanding brittle rock mass behavior to integrate new and powerful observational and numerical methods with multi-functional 3-D imaging and visualization techniques. Since 1994, Swedish Nuclear Fuel and Waste Management Company (SKB) have identified the need for a better understanding of radionuclide transport and retention processes in fractured rock. As a cooperation project between Sweden and China, we sampled a number of rock specimens for analyze rock fracture network by optical image technique. The samples are resin injected, in which way; opened fractures can be seen clearly by means of UV (Ultraviolet) light illumination. In the study period, we used different optical focuses to obtain the images from the same samples; we found that Image resolution influences on porosity determination of resin injected rock mass. This paper presents and discusses the six issues based on our research results: (1) Fracture porosity increases as camera focus distance decreases; (2) Porosity increases as illumination increases in resin injected fracture images; (3) To roughly estimate the porosity, the low resolution image can be used; (4) To collect more details of fracture information, the high resolution image is needed; (5) The resolution of image should be determined based on the aim of fracture analysis; (6) To acquire high resolution image, constructing a special illumination (standard) box maybe helpful to avoid light reflection and diffusion.

  7. Determination of elemental composition of volatile organic compounds from Chinese rose oil by spectral accuracy and mass accuracy.

    Science.gov (United States)

    Zhou, Wei; Zhang, Yaheng; Xu, Hongliang; Gu, Ming

    2011-10-30

    Elemental composition determination of volatile organic compounds through high mass accuracy and isotope pattern matching could not be routinely achieved with a unit-mass resolution mass spectrometer until the recent development of the comprehensive instrument line-shape calibration technology. Through this unique technology, both m/z values and mass spectral peak shapes are calibrated simultaneously. Of fundamental importance is that calibrated mass spectra have symmetric and mathematically known peak shapes, which makes it possible to deconvolute overlapped monoisotopes and their (13)C-isotope peaks and achieve accurate mass measurements. The key experimental requirements for the measurements are to acquire true raw data in a profile or continuum mode with the acquisition threshold set to zero. A total of 13 ions from Chinese rose oil were analyzed with internal calibration. Most of the ions produced high mass accuracy of better than 5 mDa and high spectral accuracy of better than 99%. These results allow five tested ions to be identified with unique elemental compositions and the other eight ions to be determined as a top match from multiple candidates based on spectral accuracy. One of them, a coeluted component (Nerol) with m/z 154, could not be identified by conventional GC/MS (gas chromatography/mass spectrometry) and library search. Such effective determination for elemental compositions of the volatile organic compounds with a unit-mass resolution quadrupole system is obviously attributed to the significant improvement of mass accuracy. More importantly, high spectral accuracy available through the instrument line-shape calibration enables highly accurate isotope pattern recognition for unknown identification.

  8. Metabolite signal identification in accurate mass metabolomics data with MZedDB, an interactive m/z annotation tool utilising predicted ionisation behaviour 'rules'

    Directory of Open Access Journals (Sweden)

    Snowdon Stuart

    2009-07-01

    Full Text Available Abstract Background Metabolomics experiments using Mass Spectrometry (MS technology measure the mass to charge ratio (m/z and intensity of ionised molecules in crude extracts of complex biological samples to generate high dimensional metabolite 'fingerprint' or metabolite 'profile' data. High resolution MS instruments perform routinely with a mass accuracy of Results Metabolite 'structures' harvested from publicly accessible databases were converted into a common format to generate a comprehensive archive in MZedDB. 'Rules' were derived from chemical information that allowed MZedDB to generate a list of adducts and neutral loss fragments putatively able to form for each structure and calculate, on the fly, the exact molecular weight of every potential ionisation product to provide targets for annotation searches based on accurate mass. We demonstrate that data matrices representing populations of ionisation products generated from different biological matrices contain a large proportion (sometimes > 50% of molecular isotopes, salt adducts and neutral loss fragments. Correlation analysis of ESI-MS data features confirmed the predicted relationships of m/z signals. An integrated isotope enumerator in MZedDB allowed verification of exact isotopic pattern distributions to corroborate experimental data. Conclusion We conclude that although ultra-high accurate mass instruments provide major insight into the chemical diversity of biological extracts, the facile annotation of a large proportion of signals is not possible by simple, automated query of current databases using computed molecular formulae. Parameterising MZedDB to take into account predicted ionisation behaviour and the biological source of any sample improves greatly both the frequency and accuracy of potential annotation 'hits' in ESI-MS data.

  9. Determination of Baylisascaris schroederi infection in wild giant pandas by an accurate and sensitive PCR/CE-SSCP method.

    Directory of Open Access Journals (Sweden)

    Wenping Zhang

    Full Text Available It has been recognized that other than habitat loss, degradation and fragmentation, the infection of the roundworm Baylisascaris schroederi (B. schroederi is one of the major causes of death in wild giant pandas. However, the prevalence and intensity of the parasite infection has been inconsistently reported through a method that uses sedimentation-floatation followed by a microscope examination. This method fails to accurately determine infection because there are many bamboo residues and/or few B. schroederi eggs in the examined fecal samples. In the present study, we adopted a method that uses PCR and capillary electrophoresis combined with a single-strand conformation polymorphism analysis (PCR/CE-SSCP to detect B. schroederi infection in wild giant pandas at a nature reserve, and compared it to the traditional microscope approach. The PCR specifically amplified a single band of 279-bp from both fecal samples and positive controls, which was confirmed by sequence analysis to correspond to the mitochondrial COII gene of B. schroederi. Moreover, it was demonstrated that the amount of genomic DNA was linearly correlated with the peak area of the CE-SSCP analysis. Thus, our adopted method can reliably detect the infectious prevalence and intensity of B. schroederi in wild giant pandas. The prevalence of B. schroederi was found to be 54% in the 91 fecal samples examined, and 48% in the fecal samples of 31 identified individual giant pandas. Infectious intensities of the 91 fecal samples were detected to range from 2.8 to 959.2 units/gram, and from 4.8 to 959.2 units/gram in the fecal samples of the 31 identified giant pandas. For comparison, by using the traditional microscope method, the prevalence of B. schroederi was found to be only 33% in the 91 fecal samples, 32% in the fecal samples of the 31 identified giant pandas, and no reliable infectious intensity was observed.

  10. CLASH-VLT: Insights on the mass substructures in the Frontier Fields Cluster MACS J0416.1-2403 through accurate strong lens modeling

    CERN Document Server

    Grillo, C; Rosati, P; Mercurio, A; Balestra, I; Munari, E; Nonino, M; Caminha, G B; Lombardi, M; De Lucia, G; Borgani, S; Gobat, R; Biviano, A; Girardi, M; Umetsu, K; Coe, D; Koekemoer, A M; Postman, M; Zitrin, A; Halkola, A; Broadhurst, T; Sartoris, B; Presotto, V; Annunziatella, M; Maier, C; Fritz, A; Vanzella, E; Frye, B

    2014-01-01

    We present a detailed mass reconstruction and a novel study on the substructure properties in the core of the CLASH and Frontier Fields galaxy cluster MACS J0416.1-2403. We show and employ our extensive spectroscopic data set taken with the VIMOS instrument as part of our CLASH-VLT program, to confirm spectroscopically 10 strong lensing systems and to select a sample of 175 plausible cluster members to a limiting stellar mass of log(M_*/M_Sun) ~ 8.6. We reproduce the measured positions of 30 multiple images with a remarkable median offset of only 0.3" by means of a comprehensive strong lensing model comprised of 2 cluster dark-matter halos, represented by cored elliptical pseudo-isothermal mass distributions, and the cluster member components. The latter have total mass-to-light ratios increasing with the galaxy HST/WFC3 near-IR (F160W) luminosities. The measurement of the total enclosed mass within the Einstein radius is accurate to ~5%, including systematic uncertainties. We emphasize that the use of multip...

  11. Determination of metals in composite diet samples by inductively coupled plasma-mass spectrometry.

    Science.gov (United States)

    Melnyk, Lisa Jo; Morgan, Jeffrey N; Fernando, Reshan; Pellizzari, Edo D; Akinbo, Olujide

    2003-01-01

    A study was conducted to evaluate the applicability of inductively coupled plasma-mass spectrometry (ICP-MS) techniques for determination of metals in composite diets. Aluminum, cadmium, chromium, copper, lead, manganese, nickel, vanadium, and zinc were determined by this method. Atmospheric pressure microwave digestion was used to solubilize analytes in homogenized composite diet samples, and this procedure was followed by ICP-MS analysis. Recovery of certified elements from standard reference materials ranged from 92 to 119% with relative standard deviations (RSDs) of 0.4-1.9%. Recovery of elements from fortified composite diet samples ranged from 75 to 129% with RSDs of 0-11.3%. Limits of detection ranged from 1 to 1700 ng/g; high values were due to significant amounts of certain elements naturally present in composite diets. Results of this study demonstrate that low-resolution quadrupole-based ICP-MS provides precise and accurate measurements of the elements tested in composite diet samples.

  12. Determining the mass of Didymos' secondary by visual imaging

    Science.gov (United States)

    Grieger, Bjoern; Kueppers, Michael

    2016-10-01

    A critical requirement for the Asteroid Impact Mission (AIM) is the ability to determine the mass of Didymos' secondary with an accuracy of about 10 %. The conventional approach to estimate the mass of a solar system body through its gravitational effect by tracking the spacecraft trajectory is only marginally viable for Didymos' secondary. Instead, the idea to measure the "wobble" of the primary around the common centre of gravity has been put forward. This wobble with an expected radius of about 10 m can possible be measured either by means of optical or radar ranging devices or by direct observation with the Visual Imaging System (VIS). Here, we investigate the latter approach.We approach the problem of estimating the wobble in two steps: In the first step, the spacecraft trajectory relative to the primary asteroid is reconstructed from the locations of landmarks in images. This relative trajectory comprises the wobble. In the second step, the magnitude of the wobble is extracted from the reconstructed trajectory.In this preliminary investigation, we do not deal with the problem of landmark identification and determination of their location in images. We just randomly generate landmark positions in the body fixed frame employing a shape model based on radar observations and simulate observations as inertial viewing directions from the spacecraft (with some error). Then we solve simultaneously for the landmark positions in the body fixed frame, the orientation of the asteroid at each image acquisition time, and the spacecraft trajectory relative to the asteroid. This reconstruction is done without any a priori knowledge or modelling of spacecraft trajectory or asteroid rotation. In order to extract the wobble from the reconstructed trajectory in the second step, we only assume that we know the period and the direction of the wobble from the orbit of the secondary.We conduct Monte Carlo simulations for various scenarios and assess the accuracy of the determination

  13. Exoplanet mass determination using precision imaging astrometry and coronagraphy

    Science.gov (United States)

    Bendek, Eduardo; Belikov, Ruslan; Finan, Emily R.; Guyon, Olivier; Pluzhnik, Eugene; Ammons, Stephen

    2017-01-01

    Performing simultaneous high-contrast imaging and astrometry observations of a star increases the detection efficiency and characterization accuracy of single- and multiple- planetary systems around nearby stars. Combining the data generated with both techniques allows solving the Semi-Major Axis, period, and planetary mass in the system faster and more precisely than using imaging or astrometry data separately. In addition, it allows the planetary mass to be measured independently from its brightness, resolving the mass/albedo degeneracy when only direct imaging observations are available. Independent albedo determination allows calibrated planet photometry to be obtained, enabling better atmosphere characterization. To perform both direct imaging and astrometry observations, the telescope requires two instruments: a high-performance coronagraph to perform direct imaging, and a wide field camera astrometry accuracy able to deliver sub-micro arc second astrometry accuracy if earth-like planetary science is pursued. Such accuracy is only possible after calibrating relative distortions between astrometry observations, which at the sub-micro arc second regime dominates the error budget. We propose to utilize a diffractive pupil, in which an array of dots on the primary mirror generates polychromatic diffraction spikes in the focal plane, to calibrate the dynamic distortions of the optical system. In this talk, we present the results of the NASA TDEM effort to demonstrate the diffractive pupil concept on wide-field images while simultaneously performing high-contrast imaging. We also discuss the opportunity that this mission architecture could offer to future probe missions and flagships such as HabEX and LUVOIR.

  14. Determination of effective axion masses in the helium-3 buffer of CAST

    Energy Technology Data Exchange (ETDEWEB)

    Ruz, J

    2011-11-18

    The CERN Axion Solar Telescope (CAST) is a ground based experiment located in Geneva (Switzerland) searching for axions coming from the Sun. Axions, hypothetical particles that not only could solve the strong CP problem but also be one of the favored candidates for dark matter, can be produced in the core of the Sun via the Primakoff effect. They can be reconverted into X-ray photons on Earth in the presence of strong electromagnetic fields. In order to look for axions, CAST points a decommissioned LHC prototype dipole magnet with different X-ray detectors installed in both ends of the magnet towards the Sun. The analysis of the data acquired during the first phase of the experiment yielded the most restrictive experimental upper limit on the axion-to-photon coupling constant for axion masses up to about 0.02 eV/c{sup 2}. During the second phase, CAST extends its mass sensitivity by tuning the electron density present in the magnetic field region. Injecting precise amounts of helium gas has enabled CAST to look for axion masses up to 1.2 eV/c{sup 2}. This paper studies the determination of the effective axion masses scanned at CAST during its second phase. The use of a helium gas buffer at temperatures of 1.8 K has required a detailed knowledge of the gas density distribution. Complete sets of computational fluid dynamic simulations validated with experimental data have been crucial to obtain accurate results.

  15. Determining protoplanetary disk gas masses from CO isotopologues line observations

    CERN Document Server

    Miotello, Anna; Kama, Mihkel; Bruderer, Simon

    2016-01-01

    Despite intensive studies of protoplanetary disks, there is still no reliable way to determine their total mass and their surface density distribution, quantities that are crucial for describing both the structure and the evolution of disks up to the formation of planets. The goal of this work is to use less abundant CO isotopologues, whose detection is routine for ALMA, to infer the gas mass of disks. Isotope-selective effects need to be taken into account in the analysis, because they can significantly modify CO isotopologues line intensities. CO isotope-selective photodissociation has been implemented in the physical-chemical code DALI and 800 disk models have been run for a range of disk and stellar parameters. Dust and gas temperature structures have been computed self-consistently, together with a chemical calculation of the main species. Both disk structure and stellar parameters have been investigated. Total fluxes have been ray-traced for different CO isotopologues and for various transitions for dif...

  16. Top mass determination, Higgs inflation, and vacuum stability

    CERN Document Server

    Branchina, Vincenzo; Platania, Alessia

    2014-01-01

    The possibility that new physics beyond the Standard Model (SM) appears only at the Planck scale $M_P$ is often considered. However, it is usually argued that new physics interactions at $M_P$ do not affect the SM stability phase diagram, so the latter is obtained neglecting these terms. According to this diagram, for the current experimental values of the top and Higgs masses, our universe lives in a metastable state (with very long lifetime), near the edge of stability. Contrary to these expectations, however, we show that the stability phase diagram strongly depends on new physics and that, despite claims to the contrary, a more precise determination of the top (as well as of the Higgs) mass will not allow to discriminate between stability, metastability or criticality of the electroweak vacuum. At the same time, we show that the conditions needed for the realization of Higgs inflation scenarios (all obtained neglecting new physics) are too sensitive to the presence of new interactions at $M_P$. Therefore,...

  17. CLASH-VLT: INSIGHTS ON THE MASS SUBSTRUCTURES IN THE FRONTIER FIELDS CLUSTER MACS J0416.1–2403 THROUGH ACCURATE STRONG LENS MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Grillo, C. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Suyu, S. H.; Umetsu, K. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Rosati, P.; Caminha, G. B. [Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, Via Saragat 1, I-44122 Ferrara (Italy); Mercurio, A. [INAF - Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli (Italy); Balestra, I.; Munari, E.; Nonino, M.; De Lucia, G.; Borgani, S.; Biviano, A.; Girardi, M. [INAF - Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, I-34143, Trieste (Italy); Lombardi, M. [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, I-20133 Milano (Italy); Gobat, R. [Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Universitè Paris Diderot, Irfu/Service d' Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif sur Yvette (France); Coe, D.; Koekemoer, A. M.; Postman, M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21208 (United States); Zitrin, A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Halkola, A., E-mail: grillo@dark-cosmology.dk; and others

    2015-02-10

    We present a detailed mass reconstruction and a novel study on the substructure properties in the core of the Cluster Lensing And Supernova survey with Hubble (CLASH) and Frontier Fields galaxy cluster MACS J0416.1–2403. We show and employ our extensive spectroscopic data set taken with the VIsible Multi-Object Spectrograph instrument as part of our CLASH-VLT program, to confirm spectroscopically 10 strong lensing systems and to select a sample of 175 plausible cluster members to a limiting stellar mass of log (M {sub *}/M {sub ☉}) ≅ 8.6. We reproduce the measured positions of a set of 30 multiple images with a remarkable median offset of only 0.''3 by means of a comprehensive strong lensing model comprised of two cluster dark-matter halos, represented by cored elliptical pseudo-isothermal mass distributions, and the cluster member components, parameterized with dual pseudo-isothermal total mass profiles. The latter have total mass-to-light ratios increasing with the galaxy HST/WFC3 near-IR (F160W) luminosities. The measurement of the total enclosed mass within the Einstein radius is accurate to ∼5%, including the systematic uncertainties estimated from six distinct mass models. We emphasize that the use of multiple-image systems with spectroscopic redshifts and knowledge of cluster membership based on extensive spectroscopic information is key to constructing robust high-resolution mass maps. We also produce magnification maps over the central area that is covered with HST observations. We investigate the galaxy contribution, both in terms of total and stellar mass, to the total mass budget of the cluster. When compared with the outcomes of cosmological N-body simulations, our results point to a lack of massive subhalos in the inner regions of simulated clusters with total masses similar to that of MACS J0416.1–2403. Our findings of the location and shape of the cluster dark-matter halo density profiles and on the cluster substructures provide

  18. The link between quasar broad-line region and galaxy-scale outflows and accurate CIV-based black hole masses

    Science.gov (United States)

    Coatman, Liam; Hewett, Paul C.; Banerji, Manda; Richards, Gordon T.; Hennawi, Joseph F.; Prochaska, Jason X.

    2017-01-01

    Accurate black-hole (BH) mass estimates for high-redshift (z>2) quasars are essential for better understanding the relationship between super-massive BH accretion and star formation. Progress is currently limited by the large systematic errors in virial BH-masses derived from the CIV broad emission line, which is often significantly blueshifted relative to systemic, most likely due to outflowing gas in the quasar broad-line region. We have assembled Balmer-line based BH masses for a large sample of 230 high-luminosity (1045.5-1048 ergs-1), redshift 1.5blueshifts seen in the quasar population. We find the CIV-based BH-masses to be larger than the corresponding Balmer line-based masses by almost an order of magnitude at the most extreme blueshifts (˜5000 kms-1). An empirical correction to the CIV BH-masses is derived, which depends only on the properties of the CIV line itself (i.e. blueshift and FWHM). We show that this new correction now enables the derivation of un-biased CIV-based virial BH masses for the majority of high-luminosity, high-redshift quasars.In the same high-luminosity quasar sample, we find the narrow [OIII] emission to be weaker and more asymmetric than is generally found in lower-luminosity AGN and that a significant fraction of our quasars have exceptionally broad (FWHM > 3000 kms-1), blueshifted [OIII] emission. We find a strong correlation between the CIV and [OIII] blueshifts. This correlation holds even for quasars at fixed luminosity and suggests that broad line region outflows in quasars are connected to galaxy-scale winds.

  19. Selective and Accurate Determination Method of Propofol in Human Plasma by Mixed-Mode Cation Exchange Cartridge and GC-MS.

    Science.gov (United States)

    Pyo, Jae Sung

    2016-01-01

    A gas chromatography-mass spectrometry (GC-MS) method for the determination of propofol in human plasma has been developed and validated. Propofol was extracted from human plasma by using mixed-mode cation exchange/reversed-phase (MCX) cartridges. As propofol easily volatilizes during concentration, 100% methanol was injected directly into GC-MS to elute propofol. Despite avoiding concentration process of the eluted solution, lower limit of quantization (LLOQ) of propofol was 25 ng/mL. The validated method exhibited good linearity (R (2) = 0.9989) with accuracy and precision -5.8%~11.7% and 3.7%~11.6%, respectively. The other validation parameters, recovery and matrix effect, ranged from 96.6% to 99.4% and 95.3% to 101.4%, respectively. Propofol standard was quantified to evaluate possible loss due to the concentration processes, nitrogen gas and centrifugal vacuum. These two concentration processes resulted in notable decrease in the quantity of propofol, signifying avoiding any concentration processes during propofol quantification. Also, to confirm suitability of the developed method, authentic human plasma samples were analyzed. The selective assay method using MCX cartridge and GC-MS facilitated quantification of propofol in plasma sample accurately by preventing any losses due to the concentration processes.

  20. Selective and Accurate Determination Method of Propofol in Human Plasma by Mixed-Mode Cation Exchange Cartridge and GC-MS

    Directory of Open Access Journals (Sweden)

    Jae Sung Pyo

    2016-01-01

    Full Text Available A gas chromatography-mass spectrometry (GC-MS method for the determination of propofol in human plasma has been developed and validated. Propofol was extracted from human plasma by using mixed-mode cation exchange/reversed-phase (MCX cartridges. As propofol easily volatilizes during concentration, 100% methanol was injected directly into GC-MS to elute propofol. Despite avoiding concentration process of the eluted solution, lower limit of quantization (LLOQ of propofol was 25 ng/mL. The validated method exhibited good linearity (R2=0.9989 with accuracy and precision −5.8%~11.7% and 3.7%~11.6%, respectively. The other validation parameters, recovery and matrix effect, ranged from 96.6% to 99.4% and 95.3% to 101.4%, respectively. Propofol standard was quantified to evaluate possible loss due to the concentration processes, nitrogen gas and centrifugal vacuum. These two concentration processes resulted in notable decrease in the quantity of propofol, signifying avoiding any concentration processes during propofol quantification. Also, to confirm suitability of the developed method, authentic human plasma samples were analyzed. The selective assay method using MCX cartridge and GC-MS facilitated quantification of propofol in plasma sample accurately by preventing any losses due to the concentration processes.

  1. Masses of the components of SB2 binaries observed with Gaia. III. Accurate SB2 orbits for 10 binaries and masses of HIP 87895

    CERN Document Server

    Kiefer, Flavien; Arenou, Frédéric; Pourbaix, Dimitri; Famaey, Benoit; Guillout, Patrick; Lebreton, Yveline; Gómez-Morán, Ada Nebot; Mazeh, Tsevi; Salomon, Jean-Baptiste; Soubiran, Caroline; Tal-Or, Lev

    2016-01-01

    In anticipation of the Gaia astrometric mission, a large sample of spectroscopic binaries has been observed since 2010 with the SOPHIE spectrograph at the Haute--Provence Observatory. Our aim is to derive the orbital elements of double-lined spectroscopic binaries (SB2s) with an accuracy sufficient to finally obtain the masses of the components with relative errors as small as 1 % when the astrometric measurements of Gaia are taken into account. In this paper we present the results from five years of observations of 10 SB2 systems with periods ranging from 37 to 881 days. Using the TODMOR algorithm we computed radial velocities from the spectra, and then derived the orbital elements of these binary systems. The minimum masses of the components are then obtained with an accuracy better than 1.2 % for the ten binaries. Combining the radial velocities with existing interferometric measurements, we derived the masses of the primary and secondary components of HIP 87895 with an accuracy of 0.98 % and 1.2 % respect...

  2. Dual electrospray ionization source for confident generation of accurate mass tags using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry.

    Science.gov (United States)

    Nepomuceno, Angelito I; Muddiman, David C; Bergen, H Robert; Craighead, James R; Burke, Michael J; Caskey, Patrick E; Allan, Jonathan A

    2003-07-15

    Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) has rapidly established a prominent role in proteomics because of its unparalleled resolving power, sensitivity and ability to achieve high mass measurement accuracy (MMA) simultaneously. However, space-charge effects must be quantitatively, routinely, and confidently corrected because they are known to profoundly influence MMA. We argue that the most effective way to account for space-charge effects is to introduce an internal mass calibrant (IMC) using a dual electrospray ionization (ESI) source where the IMC is added from a separate ESI emitter. The major disadvantage of our initial dual ESI source to achieve high MMA, and arguably the only one, was the time required to switch between the analyte emitter and IMC emitter (i.e., >300 ms). While this "switching time" was acceptable for direct infusion experiments, it did not lend itself to high-throughput applications or when conducting on-line liquid separations. In this report, we completely redesigned the dual ESI source and demonstrate several key attributes. First, the new design allows for facile alignment of ESI emitters, undetectable vibration, and the ability to extend to multiple emitters. Second, the switching time was reduced to IMC to be accumulated "simultaneously" in the external ion reservoir and injected as a single ion packet into the ion cyclotron resonance cell, eliminating the need for a separate accumulation and ion injection event for the IMC. Third, by using a high concentration of the IMC, the residence time on this emitter could be reduced to approximately 80 ms, allowing for more time spent accumulating analyte ions of significantly lower concentration. Fourth, multiplexed on-line separations can be carried out providing increased throughput. Specifically, the new dual ESI source has demonstrated its ability to produce a stable ion current over a 45-min time period at 7 T resulting in mass accuracies of 1.08 ppm +/- 0

  3. Determining the minimum mass and cost of a magnetic refrigerator

    CERN Document Server

    Bjørk, R; Bahl, C R H; Pryds, N

    2014-01-01

    An expression is determined for the mass of the magnet and magnetocaloric material needed for a magnetic refrigerator and these are determined using numerical modeling for both parallel plate and packed sphere bed regenerators as function of temperature span and cooling power. As magnetocaloric material Gd or a model material with a constant adiabatic temperature change, representing a infinitely linearly graded refrigeration device, is used. For the magnet a maximum figure of merit magnet or a Halbach cylinder is used. For a cost of \\$40 and \\$20 per kg for the magnet and magnetocaloric material, respectively, the cheapest 100 W parallel plate refrigerator with a temperature span of 20 K using Gd and a Halbach magnet has 0.8 kg of magnet, 0.3 kg of Gd and a cost of \\$35. Using the constant material reduces this cost to \\$25. A packed sphere bed refrigerator with the constant material costs \\$7. It is also shown that increasing the operation frequency reduces the cost. Finally, the lowest cost is also found a...

  4. Quantitative interpretation of tracks for determination of body mass.

    Science.gov (United States)

    Schanz, Tom; Lins, Yvonne; Viefhaus, Hanna; Barciaga, Thomas; Läbe, Sashima; Preuschoft, Holger; Witzel, Ulrich; Sander, P Martin

    2013-01-01

    To better understand the biology of extinct animals, experimentation with extant animals and innovative numerical approaches have grown in recent years. This research project uses principles of soil mechanics and a neoichnological field experiment with an African elephant to derive a novel concept for calculating the mass (i.e., the weight) of an animal from its footprints. We used the elephant's footprint geometry (i.e., vertical displacements, diameter) in combination with soil mechanical analyses (i.e., soil classification, soil parameter determination in the laboratory, Finite Element Analysis (FEA) and gait analysis) for the back analysis of the elephant's weight from a single footprint. In doing so we validated the first component of a methodology for calculating the weight of extinct dinosaurs. The field experiment was conducted under known boundary conditions at the Zoological Gardens Wuppertal with a female African elephant. The weight of the elephant was measured and the walking area was prepared with sediment in advance. Then the elephant was walked across the test area, leaving a trackway behind. Footprint geometry was obtained by laser scanning. To estimate the dynamic component involved in footprint formation, the velocity the foot reaches when touching the subsoil was determined by the Digital Image Correlation (DIC) technique. Soil parameters were identified by performing experiments on the soil in the laboratory. FEA was then used for the backcalculation of the elephant's weight. With this study, we demonstrate the adaptability of using footprint geometry in combination with theoretical considerations of loading of the subsoil during a walk and soil mechanical methods for prediction of trackmakers weight.

  5. High-Resolution Photoionization, Photoelectron and Photodissociation Studies. Determination of Accurate Energetic and Spectroscopic Database for Combustion Radicals and Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Cheuk-Yiu [Univ. of California, Davis, CA (United States)

    2016-04-25

    The main goal of this research program was to obtain accurate thermochemical and spectroscopic data, such as ionization energies (IEs), 0 K bond dissociation energies, 0 K heats of formation, and spectroscopic constants for radicals and molecules and their ions of relevance to combustion chemistry. Two unique, generally applicable vacuum ultraviolet (VUV) laser photoion-photoelectron apparatuses have been developed in our group, which have used for high-resolution photoionization, photoelectron, and photodissociation studies for many small molecules of combustion relevance.

  6. Determinants of body mass index in children and adolescents

    Directory of Open Access Journals (Sweden)

    Bukara-Radujković Gordana

    2008-01-01

    Full Text Available INTRODUCTION Body Mass Index (BMI in boys and girls is predicted by parental BMI, age and occupation. OBJECTIVE Correlation of BMI among children and adolescents in Banjaluka region (Bosnia and Herzegovina and parental age, BMI, parents’ educational level and occupation, as well as the number of family members were investigated as the possible determinants of overweight and obesity in childhood. METHOD The study included 1204 children and adolescents (578 males, 626 females, 6-17 years old from primary and secondary schools in the Banjaluka region. BMI was calculated from height and weight using the standard formula. Each subject along with his parents answered the questionnaire that contained information about parents’ height and weight, educational level and occupation, as well as the number of family members. RESULTS In all studied children, the prevalence of overweight was 12.2% and of obesity 6.1%. Strong positive correlation was found between parental BMI and age (older than 40 years in males and females (p<0.001, while parental higher BMI and higher educational level had positive correlation only in males (p<0.001. The number of family members showed negative correlation with overweight/obesity only in females. CONCLUSION The prevalence of overweight and obesity in children’s population in the Banjaluka region is 12.2% and 6.1%, respectively. There is a positive correlation of overweight and obesity in children with parental overweight and obesity, as well as older age, and parental higher educational level.

  7. Mass Hierarchy Determination Using Neutrinos from Multiple Reactors

    CERN Document Server

    Ciuffoli, Emilio; Zhang, Xinmin

    2012-01-01

    We report the results of Monte Carlo simulations of a medium baseline reactor neutrino experiment. The difference in baselines resulting from the 1 km separations of Daya Bay and Ling Ao reactors reduces the amplitudes of 1-3 oscillations at low energies, decreasing the sensitivity to the neutrino mass hierarchy. A perpendicular detector location eliminates this effect. We simulate experiments under several mountains perpendicular to the Daya Bay/Ling Ao reactors, considering in particular the background from the TaiShan and YangJiang reactor complexes. In general the hierarchy can be determined most reliably underneath the 1000 meter mountain BaiYunZhang, which is 44.5 km from Daya Bay. If some planned reactors are not built then nearby 700 meter mountains at 47-51 km baselines gain a small advantage. Neglecting their low overhead burdens, hills near DongKeng would be the optimal locations. We use a weighted Fourier transform to avoid a spurious dependence on the high energy neutrino spectrum and find that a...

  8. Simple and accurate measurement of carbamazepine in surface water by use of porous membrane-protected micro-solid-phase extraction coupled with isotope dilution mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Teo, Hui Ling [Chemical Metrology Division, Applied Sciences Group, Health Sciences Authority, 1 Science Park Road, #01-05/06, The Capricorn, Singapore Science Park II, Singapore 117528 (Singapore); Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Wong, Lingkai [Chemical Metrology Division, Applied Sciences Group, Health Sciences Authority, 1 Science Park Road, #01-05/06, The Capricorn, Singapore Science Park II, Singapore 117528 (Singapore); Liu, Qinde, E-mail: liu_qinde@hsa.gov.sg [Chemical Metrology Division, Applied Sciences Group, Health Sciences Authority, 1 Science Park Road, #01-05/06, The Capricorn, Singapore Science Park II, Singapore 117528 (Singapore); Teo, Tang Lin; Lee, Tong Kooi [Chemical Metrology Division, Applied Sciences Group, Health Sciences Authority, 1 Science Park Road, #01-05/06, The Capricorn, Singapore Science Park II, Singapore 117528 (Singapore); Lee, Hian Kee, E-mail: chmleehk@nus.edu.sg [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore)

    2016-03-17

    To achieve fast and accurate analysis of carbamazepine in surface water, we developed a novel porous membrane-protected micro-solid-phase extraction (μ-SPE) method, followed by liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS) analysis. The μ-SPE device (∼0.8 × 1 cm) was fabricated by heat-sealing edges of a polypropylene membrane sheet to devise a bag enclosing the sorbent. The analytes (both carbamazepine and isotope-labelled carbamazepine) were first extracted by μ-SPE device in the sample (10 mL) via agitation, then desorbed in an organic solvent (1 mL) via ultrasonication. Several parameters such as organic solvent for pre-conditioning of μ-SPE device, amount of sorbent, adsorption time, and desorption solvent and time were investigated to optimize the μ-SPE efficiency. The optimized method has limits of detection and quantitation estimated to be 0.5 ng L{sup −1} and 1.6 ng L{sup −1}, respectively. Surface water samples spiked with different amounts of carbamazepine (close to 20, 500, and 1600 ng L{sup −1}, respectively) were analysed for the validation of method precision and accuracy. Good precision was obtained as demonstrated by relative standard deviations of 0.7% for the samples with concentrations of 500 and 1600 ng kg{sup −1}, and 5.8% for the sample with concentration of 20 ng kg{sup −1}. Good accuracy was also demonstrated by the relative recoveries in the range of 96.7%–103.5% for all samples with uncertainties of 1.1%–5.4%. Owing to the same chemical properties of carbamazepine and isotope-labelled carbamazepine, the isotope ratio in the μ-SPE procedure was accurately controlled. The use of μ-SPE coupled with IDMS analysis significantly facilitated the fast and accurate measurement of carbamazepine in surface water. - Highlights: • μ-SPE coupled with IDMS for the measurement of carbamazepine. • The method is the first report of coupling μ-SPE with IDMS. • μ-SPE is fast, time

  9. [Determination of residual glycol ethers in leather and leather products by gas chromatography/mass spectrometry].

    Science.gov (United States)

    Wang, Ghengyun; Zhang, Weiya; Li, Lixia; Shen, Yalei; Lin, Junfeng; Xie, Tangtang; Chu, Naiqing

    2014-08-01

    An effective method was established for the simultaneous determination of residual glycol ethers in leather and leather products by gas chromatography/mass spectrometry. Glycol ethers in leather and leather products were ultrasonically extracted at 45 °C, using ethyl acetate as the extraction solvent. The extracts were purified by solid phase extraction (SPE) columns, and then analyzed by gas chromatography/mass spectrometry in selected ion monitoring mode. The content of each analyte was calibrated by external standard method. The limit of detection of ethylene glycol ethyl ether (EGEE) was 0. 10 mg/kg under the condition of signal to noise (S/N) of 3 and the limits of the other 11 glycol ethers were all less than 0.05 mg/kg. The spiked recoveries varied from 81. 2% to 95. 5% at three different spiked levels with the relative standard deviations (RSDs) ranged from 1.4% to 6. 6%. The proposed method is simple, rapid and accurate, with the limits of detection much less than the requirements of the Regulation Concerning Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) of European Union. It is applicable to the determination of residual glycol ethers in leather and leather products, and provides a reference for the relevant testing standards.

  10. [Determination of 21 fragrance allergens in toys by gas chromatography-ion trap mass spectrometry].

    Science.gov (United States)

    Lü, Qing; Zang, Qing; Bai, Hua; Li, Haiyu; Kang, Suyuan; Wang, Chao

    2012-05-01

    A method of gas chromatography-ion trap mass spectrometry (GC-IT-MS) was developed for the determination of 21 fragrance allergens in sticker toys, plush toys and plastic toys. The experimental conditions, such as sample pretreatment conditions, and the analytical conditions of GC-IT-MS, were optimized. The sticker toy samples and plush toy samples were extracted with acetone by ultrasonic wave, and the extracts were separated on an Agilent HP-1 MS column (50 m x 0.2 mm x 0.5 microm), then determined by IT-MS and quantified by external standard method. The plastic toy samples were extracted by the dissolution-precipitation approach, cleaned up with an Envi-carb solid phase extraction column and concentrated by rotary evaporation and nitrogen blowing, then determined by GC-IT-MS and quantified by external standard method. The calibration curves showed good linearity in the range of 0.002-50 mg/L with the correlation coefficients greater than 0.996 8. The limits of quantification (LOQ, S/N > 10) were 0.02-40 mg/kg. The average recoveries of the target compounds spiked in the sample at three concentration levels were in the range of 82.2%-110.8% with the relative standard deviations (RSDs) of 0.6%-10.5%. These results show that this method is accurate and sensitive for the qualitative and quantitative determination of the 21 fragrance allergens in the 3 types of toys.

  11. Determining Central Black Hole Masses in Distant Active Galaxies

    CERN Document Server

    Vestergaard, M

    2002-01-01

    An empirical relationship, of particular interest for studies of high redshift active galactic nuclei (AGNs) and quasars, between the masses of their central black-holes and rest-frame ultraviolet (UV) parameters measured in single-epoch AGN spectra is presented. This relationship is calibrated to recently measured reverberation masses of low-redshift AGNs and quasars. An empirical relationship between single-epoch rest-frame optical spectrophotometric measurements and the central masses is also presented. The UV relationship allows reasonable estimates of the central masses to be made of high-redshift AGNs and quasars for which these masses cannot be directly or easily measured by the techniques applicable to the lower luminosity, nearby AGNs. The central mass obtained by this method can be estimated to within a factor of ~3 for most objects. This is reasonable given the intrinsic uncertainty of a factor less than 2 in the primary methods used to measure the central masses of nearby inactive and active galax...

  12. Position and mass determination of multiple particles using cantilever based mass sensors

    DEFF Research Database (Denmark)

    Dohn, Søren; Schmid, Silvan; Amiot, Fabien;

    2010-01-01

    of several added particles to the resonant frequencies of a cantilever, and an identification procedure valid for particles with different masses is proposed. The identification procedure is tested by calculating positions and mass of multiple microparticles with similar mass positioned on individual...

  13. Determination of left ventricular mass through SPECT imaging

    Science.gov (United States)

    Zárate-Morales, A.; Rodríguez-Villafuerte, M.; Martínez-Rodríguez, F.; Arévila-Ceballos, N.

    1998-08-01

    An edge detection algorithm has been applied to estimate left ventricular (LV) mass from single photon emission computed tomography (SPECT) thallium-201 images. The algorithm was validated using SPECT images of a phantom. The algorithm was applied to 20 patient studies from the Hospital de Cardiologia, Centro Médico Nacional Siglo XXI. Left ventricular masses derived from the stress and redistribution studies were highly correlated (r=0.96). The average LV masses obtained were 162±37 g and 169±34 g in the redistribution and stress studies, respectively.

  14. Generating finite element models of the knee : How accurately can we determine ligament attachment sites from MRI scans?

    NARCIS (Netherlands)

    Rachmat, H H; Janssen, D.; Zevenbergen, W J; Verkerke, G J; Diercks, R L; Verdonschot, N

    2014-01-01

    In this study, we evaluated the intra- and inter-observer variability when determining the insertion and origin sites of knee ligaments on MRI scan images. We collected data of five observers with different backgrounds, who determined the ligament attachment sites in an MRI scan of a right knee of a

  15. Absolute parameter determination in low-mass eclipsing binaries - Radiative parameters for BH Vir, ZZ UMA and CR CAS

    Science.gov (United States)

    Clement, R.; Reglero, V.; Garcia, M.; Fabregat, J.; Bravo, A.; Suso, J.

    1993-01-01

    A new uvby and H-beta monitoring program of low mass eclipsing binaries is currently being carried out in the framework of a 5-yr observational program which also involves radial velocity determinations. The scope of this work is to provide very accurate absolute astrophysical parameters: mass, radius, and effective temperatures, for main-sequence late-type stars. One of the main goals is to improve the mass-luminosity relation in the low and intermediate mass range. A second objective is to perform accurate tests of the most recent grids of evolutionary models. This program is complementary to that currently being implemented by the Copenhagen group. In this contribution we present the photometric preliminary results obtained for three of the systems included in our long-term survey: BH Vir, ZZ UMa, and CR Cas for which primary eclipses have been observed. Particular attention is paid to the determination of reddening, distances, and radiative properties. A more detailed study will be carried out when the light curves and radial velocity measurements are completed.

  16. Quantitative Proteome Analysis of Breast Cancer Cell Lines using 18O-Labeling and an Accurate Mass and Time Tag Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Patwardhan, Anil J.; Strittmatter, Eric F.; Camp, David G.; Smith, Richard D.; Pallavicini, Maria

    2006-05-01

    Proteome comparison of cell lines derived from breast cancer and normal breast epithelium provide opportunities to identify differentially expressed proteins and pathways associated with specific phenotypes. We employed trypsin-catalyzed 16O/18O peptide labeling, FTI-CR mass spectrometry, and the accurate mass and time (AMT) tag strategy to calculate compare the relative protein abundances of hundreds of proteins simultaneously in non-cancer and cancer cell lines derived from breast tissue. A reference panel of cell lines was created to facilitate comparisons of relative protein abundance amongst multiple cell lines and across multiple experiments. A peptide database generated from multidimensional LC separations and MS/MS analysis was used to facilitate subsequent AMT tag-based peptide identifications. This peptide database represented a total of 2,299 proteins, including 514 that were quantified using the AMT tag and 16O/18O strategies. Eighty-six proteins showed at least a 3-fold protein abundance change between cancer and non-cancer cell lines. A comparison of protein expression profiles with previously published gene expression data revealed that 21 of these proteins also had >3-fold differences between the non-cancer and cancer cell lines at the transcriptional level. Clustering of protein abundance ratios revealed that several groups of proteins were differentially expressed between the cancer cell lines

  17. Extensive Peptide Fractionation and y1 Ion-Based Interference Detection Method for Enabling Accurate Quantification by Isobaric Labeling and Mass Spectrometry.

    Science.gov (United States)

    Niu, Mingming; Cho, Ji-Hoon; Kodali, Kiran; Pagala, Vishwajeeth; High, Anthony A; Wang, Hong; Wu, Zhiping; Li, Yuxin; Bi, Wenjian; Zhang, Hui; Wang, Xusheng; Zou, Wei; Peng, Junmin

    2017-02-22

    Isobaric labeling quantification by mass spectrometry (MS) has emerged as a powerful technology for multiplexed large-scale protein profiling, but measurement accuracy in complex mixtures is confounded by the interference from coisolated ions, resulting in ratio compression. Here we report that the ratio compression can be essentially resolved by the combination of pre-MS peptide fractionation, MS2-based interference detection, and post-MS computational interference correction. To recapitulate the complexity of biological samples, we pooled tandem mass tag (TMT)-labeled Escherichia coli peptides at 1:3:10 ratios and added in ∼20-fold more rat peptides as background, followed by the analysis of two-dimensional liquid chromatography (LC)-MS/MS. Systematic investigation shows that quantitative interference was impacted by LC fractionation depth, MS isolation window, and peptide loading amount. Exhaustive fractionation (320 × 4 h) can nearly eliminate the interference and achieve results comparable to the MS3-based method. Importantly, the interference in MS2 scans can be estimated by the intensity of contaminated y1 product ions, and we thus developed an algorithm to correct reporter ion ratios of tryptic peptides. Our data indicate that intermediate fractionation (40 × 2 h) and y1 ion-based correction allow accurate and deep TMT profiling of more than 10 000 proteins, which represents a straightforward and affordable strategy in isobaric labeling proteomics.

  18. Screening and characterization of reactive compounds with in vitro peptide-trapping and liquid chromatography/high-resolution accurate mass spectrometry.

    Science.gov (United States)

    Wei, Cong; Chupak, Louis S; Philip, Thomas; Johnson, Benjamin M; Gentles, Robert; Drexler, Dieter M

    2014-02-01

    The present study describes a novel methodology for the detection of reactive compounds using in vitro peptide-trapping and liquid chromatography-high-resolution accurate mass spectrometry (LC-HRMS). Compounds that contain electrophilic groups can covalently bind to nucleophilic moieties in proteins and form adducts. Such adducts are thought to be associated with drug-mediated toxicity and therefore represent potential liabilities in drug discovery programs. In addition, reactive compounds identified in biological screening can be associated with data that can be misinterpreted if the reactive nature of the compound is not appreciated. In this work, to facilitate the triage of hits from high-throughput screening (HTS), a novel assay was developed to monitor the formation of covalent peptide adducts by compounds suspected to be chemically reactive. The assay consists of in vitro incubations of test compounds (under conditions of physiological pH) with synthetically prepared peptides presenting a variety of nucleophilic moieties such as cysteine, lysine, histidine, arginine, serine, and tyrosine. Reaction mixtures were analyzed using full-scan LC-HRMS, the data were interrogated using postacquisition data mining, and modified amino acids were identified by subsequent LC-HRMS/mass spectrometry. The study demonstrated that in vitro nucleophilic peptide trapping followed by LC-HRMS analysis is a useful approach for screening of intrinsically reactive compounds identified from HTS exercises, which are then removed from follow-up processes, thus obviating the generation of data from biochemical activity assays.

  19. Mass transfer coefficients determination from linear gradient elution experiments.

    Science.gov (United States)

    Pfister, David; Morbidelli, Massimo

    2015-01-02

    A procedure to estimate mass transfer coefficients in linear gradient elution chromatography is presented and validated by comparison with experimental data. Mass transfer coefficients are traditionally estimated experimentally through the van Deemter plot, which represents the HETP as a function of the fluid velocity. Up to now, the HETP was obtained under isocratic elution conditions. Unfortunately, isocratic elution experiments are often not suitable for large biomolecules which suffer from severe mass transfer hindrances. Yamamoto et al. were the first to propose a semi-empirical equation to relate HETPs measured from linear gradient elution experiments to those obtained under isocratic conditions [7]. Based on his pioneering work, the approach presented in this work aims at providing an experimental procedure supported by simple equations to estimate reliable mass transfer parameters from linear gradient elution chromatographic experiments. From the resolution of the transport model, we derived a rigorous analytical expression for the HETP in linear gradient elution chromatography.

  20. Ambient ionization-accurate mass spectrometry (AMI-AMS) for the identification of nonvisible set-off in food-contact materials.

    Science.gov (United States)

    Bentayeb, Karim; Ackerman, Luke K; Begley, Timothy H

    2012-02-29

    Set-off is the unintentional transfer of substances used in printing from the external printed surface of food packaging to the inner, food-contact surface. Ambient ionization-accurate mass spectrometry (AMI-AMS) detected and identified compounds from print set-off not visible to the human eye. AMI mass spectra from inner and outer surfaces of printed and nonprinted food packaging were compared to detect and identify nonvisible set-off components. A protocol to identify unknowns was developed using a custom open-source database of printing inks and food-packaging compounds. The protocol matched print-related food-contact surface ions with the molecular formulas of common ions, isotopes, and fragments of compounds from the database. AMI-AMS was able to detect print set-off and identify seven different compounds. Set-off on the packaging samples was confirmed using gas chromatographic-mass spectrometric (GC-MS) analysis of single-sided solvent extracts. N-Ethyl-2(and 4)-methylbenzenesulfonamide, 2,4-diphenyl-4-methyl-1(and 2)-pentene, and 2,4,7,9-tetramethyl-5-decyne-4,7-diol were present on the food-contact layer at concentrations from 0.21 to 2.7 ± 1.6 μg dm⁻², corresponding to nearly milligram per kilogram concentrations in the packaged food. Other minor set-off compounds were detected only by AMI-AMS, a fast, simple, and thorough technique to detect and identify set-off in food packaging.

  1. The use of in vitro technologies and high-resolution/accurate-mass LC-MS to screen for metabolites of 'designer' steroids in the equine.

    Science.gov (United States)

    Clarke, Adam; Scarth, James; Teale, Phil; Pearce, Clive; Hillyer, Lynn

    2011-01-01

    Detection of androgenic-anabolic steroid abuse in equine sports requires knowledge of the drug's metabolism in order to target appropriate metabolites, especially where urine is the matrix of choice. Studying 'designer' steroid metabolism is problematic since it is difficult to obtain ethical approval for in vivo metabolism studies due to a lack of toxicological data. In this study, the equine in vitro metabolism of eight steroids available for purchase on the Internet is reported; including androsta-1,4,6-triene-3,17-dione, 4-chloro,17α-methyl-androsta-1,4-diene-3,17β-diol, estra-4,9-diene-3,17-dione, 4-hydroxyandrostenedione, 20-hydroxyecdysone, 11-keto-androstenedione, 17α-methyldrostanolone, and tetrahydrogestrinone. In order to allow for retrospective analysis of sample testing data, the use of a high-resolution (HR) accurate-mass Thermo LTQ-Orbitrap liquid chromatography-mass spectrometry (LC-MS) instrument was employed for metabolite identification of underivatized sample extracts. The full scan LC-HRMS Orbitrap data were complimented by LC-HRMS/MS and gas-chromatography-mass spectrometry (GC-MS) experiments in order to provide fragmentation information and to ascertain whether GC-MS was capable of detecting any metabolite not detected by LC-HRMS. With the exception of 20-hydroxyecdysone, all compounds were found to be metabolized by equine liver S9 and/or microsomes. With the exception of 17α-methyldrostanolone, which produced metabolites that could only be detected by GC-MS, the metabolites of all other compounds could be identified using LC-HRMS, thus allowing retrospective analysis of previously acquired full-scan data resulting from routine equine drug testing screens. In summary, while in vitro techniques do not serve as a replacement for more definitive in vivo studies in all situations, their use does offer an alternative in situations where it would not be ethical to administer untested drugs to animals.

  2. Determination of omeprazole and its metabolites in human plasma by liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Kanazawa, Hideko; Okada, Akiko; Matsushima, Yoshikazu; Yokota, Hiromitsu; Okubo, Shigeo; Mashige, Fumiko; Nakahara, Kazuhiko

    2002-03-08

    Omeprazole is a benzimidazole compound that acts as a proton-pump inhibitor. Because the metabolism of omeprazole is mainly catalyzed by cytochrome P-450 (CYP) 3A4 and CYP2C19. the genetic polymorphism of CYP2C19 could be of clinical concern in the treatment of acid-related diseases with omeprazole. Therefore, a reliable method for omeprazole phenotyping is desirable in clinical situations. This study has demonstrated the determination of omeprazole and its metabolites in human plasma by liquid chromatography-three-dimensional quadrupole mass spectrometry with a sonic spray ionization interface. The analytical column was YMC-Pack Pro C18(50x2.0 mm I.D.) using acetonitrile-50 mM ammonium acetate (pH 7.25) (1:4) at a flow-rate of 0.2 ml/min. The drift voltage was 30 V. The sampling aperture was heated at 110 degrees C and Shield temperature was 230 degrees C. In the mass spectrum, the molecular ions of omeprazole, hydroxyomeprazole and omeprazole sulfone were clearly observed as base peaks. This method is sufficiently sensitive and accurate for pharmacokinetic studies of omeprazol.

  3. Implicit Priors in Galaxy Cluster Mass and Scaling Relation Determinations

    Science.gov (United States)

    Mantz, A.; Allen, S. W.

    2011-01-01

    Deriving the total masses of galaxy clusters from observations of the intracluster medium (ICM) generally requires some prior information, in addition to the assumptions of hydrostatic equilibrium and spherical symmetry. Often, this information takes the form of particular parametrized functions used to describe the cluster gas density and temperature profiles. In this paper, we investigate the implicit priors on hydrostatic masses that result from this fully parametric approach, and the implications of such priors for scaling relations formed from those masses. We show that the application of such fully parametric models of the ICM naturally imposes a prior on the slopes of the derived scaling relations, favoring the self-similar model, and argue that this prior may be influential in practice. In contrast, this bias does not exist for techniques which adopt an explicit prior on the form of the mass profile but describe the ICM non-parametrically. Constraints on the slope of the cluster mass-temperature relation in the literature show a separation based the approach employed, with the results from fully parametric ICM modeling clustering nearer the self-similar value. Given that a primary goal of scaling relation analyses is to test the self-similar model, the application of methods subject to strong, implicit priors should be avoided. Alternative methods and best practices are discussed.

  4. Determining the Mass Composition of Cosmic Rays Using Shower Universality

    Science.gov (United States)

    Biscoveanu, Andrea; Mostafa, Miguel

    2016-03-01

    The mass composition of ultra-high energy cosmic rays is an important parameter for understanding their origin. Using both fluorescence and surface detectors, The Pierre Auger Observatory measures the depth of shower maximum, Xmax, from which the mass of the primary particle can be inferred. The surface detector measurement of Xmax is based on the principle of shower universality, and increases the number of cosmic rays by at least a factor of 10 with respect to the fluorescence detector measurement since it is not limited by the duty cycle of the fluorescence telescopes. We present an event-by-event comparison of the Xmax measurements from both types of detectors for energies above 10 18 . 8 eV, and a preliminary anisotropy study discriminating by the mass of the primary particle calculated using universality.

  5. METHOD 544. DETERMINATION OF MICROCYSTINS AND NODULARIN IN DRINKING WATER BY SOLID PHASE EXTRACTION AND LIQUID CHROMATOGRAPHY/TANDEM MASS SPECTROMETRY (LC/MS/MS)

    Science.gov (United States)

    Method 544 is an accurate and precise analytical method to determine six microcystins (including MC-LR) and nodularin in drinking water using solid phase extraction and liquid chromatography tandem mass spectrometry (SPE-LC/MS/MS). The advantage of this SPE-LC/MS/MS is its sensi...

  6. A Modified Amino Acid Analysis Using PITC Derivatization for Soybeans with Accurate Determination of Cysteine and Half-Cystine

    Science.gov (United States)

    Breeding efforts to change amino acid profile of seed protein and the assessment of genetic variation for amino acid composition among soybean germplasm resources have been hampered by lack of a rapid and inexpensive method for amino acid determination. A modified procedure presented here is based p...

  7. Incorporating Biological Mass Spectrometry into Undergraduate Teaching Labs, Part 2: Peptide Identification via Molecular Mass Determination

    Science.gov (United States)

    Arnquist, Isaac J.; Beussman, Douglas J.

    2009-01-01

    Mass spectrometry has become a routine analytical tool in the undergraduate curriculum in the form of GC-MS. While relatively few undergraduate programs have incorporated biological mass spectrometry into their programs, the importance of these techniques, as demonstrated by their recognition with the 2002 Nobel Prize, will hopefully lead to…

  8. Mass spectrometric determination of early and advanced glycation in biology.

    Science.gov (United States)

    Rabbani, Naila; Ashour, Amal; Thornalley, Paul J

    2016-08-01

    Protein glycation in biological systems occurs predominantly on lysine, arginine and N-terminal residues of proteins. Major quantitative glycation adducts are found at mean extents of modification of 1-5 mol percent of proteins. These are glucose-derived fructosamine on lysine and N-terminal residues of proteins, methylglyoxal-derived hydroimidazolone on arginine residues and N(ε)-carboxymethyl-lysine residues mainly formed by the oxidative degradation of fructosamine. Total glycation adducts of different types are quantified by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry (LC-MS/MS) in multiple reaction monitoring mode. Metabolism of glycated proteins is followed by LC-MS/MS of glycation free adducts as minor components of the amino acid metabolome. Glycated proteins and sites of modification within them - amino acid residues modified by the glycating agent moiety - are identified and quantified by label-free and stable isotope labelling with amino acids in cell culture (SILAC) high resolution mass spectrometry. Sites of glycation by glucose and methylglyoxal in selected proteins are listed. Key issues in applying proteomics techniques to analysis of glycated proteins are: (i) avoiding compromise of analysis by formation, loss and relocation of glycation adducts in pre-analytic processing; (ii) specificity of immunoaffinity enrichment procedures, (iii) maximizing protein sequence coverage in mass spectrometric analysis for detection of glycation sites, and (iv) development of bioinformatics tools for prediction of protein glycation sites. Protein glycation studies have important applications in biology, ageing and translational medicine - particularly on studies of obesity, diabetes, cardiovascular disease, renal failure, neurological disorders and cancer. Mass spectrometric analysis of glycated proteins has yet to find widespread use clinically. Future use in health screening, disease diagnosis and therapeutic monitoring, and

  9. Precise Determination of 40Ti Mass by Measuring the 40Sc Isospin Analogue State

    Institute of Scientific and Technical Information of China (English)

    LIU Wei-Ping(柳卫平); E. Roeckl; M. Pfützner; L. Chulkov; A. Piechaczek; R. Raabe; I. Reusen; G. Vancraeynest; A. Wohr; M. Hellstrom2; R. Collatz; J. Benlliure; D. Cortina Gil; F. Farget; H. Grawe; Z. Hu; N. Iwasa

    2001-01-01

    The mass of 40 Ti has been determined by using the isobaric multiplet mass equation method. The experimental data of the 40Tiβ-decay were used to determine the level of the isospin analogue state of 40Sc. The ground-state mass excess and the QEc value for 40 Ti were determined to be -9060 ± 12 keV and 11 466 ± 13keV, respectively.

  10. Technical Note: How accurate can stalagmite formation temperatures be determined using vapour bubble radius measurements in fluid inclusions?

    DEFF Research Database (Denmark)

    Spadin, F.; Marti, Dominik; Hidalgo-Staub, R.

    2015-01-01

    Stalagmites are natural archives containing detailed information on continental climate variability of the past. Microthermometric measurements of fluid inclusion homogenisation temperatures allow determination of stalagmite formation temperatures by measuring the radius of stable laser-induced v......Stalagmites are natural archives containing detailed information on continental climate variability of the past. Microthermometric measurements of fluid inclusion homogenisation temperatures allow determination of stalagmite formation temperatures by measuring the radius of stable laser......-induced vapour bubbles inside the inclusions. A reliable method for precisely measuring the radius of vapour bubbles is presented. The method is applied to stalagmite samples for which the formation temperature is known. An assessment of the bubble radius measurement accuracy and how this error influences...

  11. Accurate determination of electronic transport properties of silicon wafers by nonlinear photocarrier radiometry with multiple pump beam sizes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qian [Institute of Optics and Electronics, Chinese Academy of Sciences, P. O. Box 350, Shuangliu, Chengdu 610209 (China); University of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Bincheng, E-mail: bcli@uestc.ac.cn [Institute of Optics and Electronics, Chinese Academy of Sciences, P. O. Box 350, Shuangliu, Chengdu 610209 (China); School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2015-12-07

    In this paper, photocarrier radiometry (PCR) technique with multiple pump beam sizes is employed to determine simultaneously the electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) of silicon wafers. By employing the multiple pump beam sizes, the influence of instrumental frequency response on the multi-parameter estimation is totally eliminated. A nonlinear PCR model is developed to interpret the PCR signal. Theoretical simulations are performed to investigate the uncertainties of the estimated parameter values by investigating the dependence of a mean square variance on the corresponding transport parameters and compared to that obtained by the conventional frequency-scan method, in which only the frequency dependences of the PCR amplitude and phase are recorded at single pump beam size. Simulation results show that the proposed multiple-pump-beam-size method can improve significantly the accuracy of the determination of the electronic transport parameters. Comparative experiments with a p-type silicon wafer with resistivity 0.1–0.2 Ω·cm are performed, and the electronic transport properties are determined simultaneously. The estimated uncertainties of the carrier lifetime, diffusion coefficient, and front surface recombination velocity are approximately ±10.7%, ±8.6%, and ±35.4% by the proposed multiple-pump-beam-size method, which is much improved than ±15.9%, ±29.1%, and >±50% by the conventional frequency-scan method. The transport parameters determined by the proposed multiple-pump-beam-size PCR method are in good agreement with that obtained by a steady-state PCR imaging technique.

  12. Technical Note: How accurate can stalagmite formation temperatures be determined using vapour bubble radius measurements in fluid inclusions?

    Directory of Open Access Journals (Sweden)

    F. Spadin

    2015-06-01

    Full Text Available Stalagmites are natural archives containing detailed information on continental climate variability of the past. Microthermometric measurements of fluid inclusion homogenisation temperatures allow determination of stalagmite formation temperatures by measuring the radius of stable laser-induced vapour bubbles inside the inclusions. A reliable method for precisely measuring the radius of vapour bubbles is presented. The method is applied to stalagmite samples for which the formation temperature is known. An assessment of the bubble radius measurement accuracy and how this error influences the uncertainty in determining the formation temperature is provided. We demonstrate that the nominal homogenisation temperature of a single inclusion can be determined with an accuracy of ±0.25 °C, if the volume of the inclusion is larger than 105 μm3. With this method, we could measure in a proof-of-principle investigation that the formation temperature of 10–20 yr old inclusions in a stalagmite taken from the Milandre cave is 9.87 ± 0.80 °C, while the mean annual surface temperature, that in the case of the Milandre cave correlates well with the cave temperature, was 9.6 ± 0.15 °C, calculated from actual measurements at that time, showing a very good agreement. Formation temperatures of inclusions formed during the last 450 yr are found in a temperature range between 8.4 and 9.6 °C, which corresponds to the calculated average surface temperature. Paleotemperatures can thus be determined within ±1.0 °C.

  13. Liquid chromatography-mass spectrometric determination of rufinamide in low volume plasma samples.

    Science.gov (United States)

    Gáll, Zsolt; Vancea, Szende; Dogaru, Maria T; Szilágyi, Tibor

    2013-12-01

    Quantification of rufinamide in plasma was achieved using a selective and sensitive liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method. The chromatographic separation was achieved on a reversed phase column (Zorbax SB-C18 100mm×3mm, 3.5μm) under isocratic conditions. The mobile phase consisted of a mixture of water containing 0.1% formic acid and methanol (50:50, v/v). The mass spectrometric detection of the analyte was in multiple reaction monitoring mode (MRM) using an electrospray positive ionization (ESI positive). The monitored ions were 127m/z derived from 239m/z rufinamide and 108m/z derived from 251m/z the internal standard (lacosamide). Protein precipitation with methanol was applied for sample preparation using only 50μl aliquots. The concentration range was 40-2000ng/ml for rufinamide in plasma. The limit of detection was 1.25ng/ml and the lower limit of quantification was established at 5ng/ml rufinamide concentration. Selectivity and matrix effect was verified using individual human, rat and rabbit plasma samples. Short-term, post-preparative and freeze-thaw stability was also investigated. The proposed method provides accuracy, precision and high-throughput (short runtime 4.5min) for quantitative determination of rufinamide in plasma. This is the first reported liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for analysis of rufinamide from low volume plasma samples. The LC-MS/MS method was validated according to the current official guidelines and can be applied to accurately measure rufinamide level of large number of plasma samples from clinical studies or therapeutic drug monitoring.

  14. Higher order and heavy quark mass effects in the determination of parton distribution functions

    Energy Technology Data Exchange (ETDEWEB)

    Bertone, Valerio

    2013-07-01

    The present thesis was devoted to the study of the inclusion of higher-order corrections and heavy quark mass effects in a PDF determination. This has been carried out in the NNPDF framework resulting originally in the NNPDF2.1 sets, which were at a later stage supplemented by the first LHC data leading to the most recent NNPDF2.3 sets. In Chapter 1 the concept of Parton Distribution Function (PDF) was introduced. We have shown how the analytical computation of the Deep-Inelastic-Scattering (DIS) process at order α{sub s} in QCD leads to initial-stale collinear divergences which, using the factorization theorem, can be reabsorbed into the PDFs. The energy dependence of PDFs is fully determined and the task is then reduced to the determination of the x (Bjorken variable) dependence. In Chapter 2 a detailed discussion of the factorization schemes presently available to include heavy quark mass effects into DIS structure functions has been given. It emerged that there are two possible basic approaches to the calculation of the DIS structure functions. In the first approach, the so-called Fixed-Flavour-Number Scheme (FFNS), the calculation is performed retaining the quark mass of the heavy flavours which provide a ''natural'' regulator for the infrared divergences. In the second approach, called Zero-Mass Variable-Flavour-Number Scheme (ZM-VFNS), the heavy quark masses are instead set to zero and this gives rise to the usual final-state collinear divergences that are absorbed into the PDFs. In addition, in the ZM-VFNS, the number of active flavours is assumed to increase by one unity as the energy of the process crosses the energy threshold of a given heavy quark. In order to obtain a factorization scheme that is accurate both at large and low energies, several prescriptions that interpolate between FFNS at low energy and ZM-VFNS at large energy have been proposed and implemented in as many PDF fits. In Chapter 2 they have been described showing

  15. Determination of Residual Acrylamide in Medical Polyacrylamide Hydrogel by High Performance Liquid Chromatography tandem Mass Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    WEI-WEI LI; HUI LI; ZHI-FEI LIU; QUN QIAO

    2009-01-01

    Objective To determine residual acrylamide in medical polyacrylamide hydrogel by high performance liquid chromatography tandem mass spectroscopy (HPLC-MS). Methods After 13C3 labeled acrylamide was added, the sample was extracted with water and then cleaned up with ExtrelutTM 20. The polyaerylamide hydrogel sample and 20 clinical cases were analyzed by HPLC-MS/MS and isotope dilution quantifying technique in selected reaction monitoring (SRM) mode. Results Acrylamide was separated from polyacrylamide hydrogel. The concentration of acrylamide in polyacrylamide hydrogel ranged from 3.9×109 to 3.1×108g/L in the 20 clinical cases. The peak area was favorable linear and the range was up to 3 000 μg/L. The recovery rate was 103.1% with a relative standard deviation (RSD) of 6.20%, when the mark level was 50 μg/L. Conclusion HPLC-MS is a rapid, accurate, and sensitive method for the determination of residual acrylamide in medical polyacrylamide hydrogel.

  16. Determining Central Black Hole Masses in Distant Active Galaxies

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2002-01-01

    of a factor less than 2 in the primary methods used to measure the central masses of nearby inactive and active galaxies, namely resolved gas and stellar kinematics in the underlying host galaxy and reverberation-mapping techniques. The UV relationship holds good potential for being a powerful tool to study...... stresses the need for better observational constraints to be placed on this relationship. The empirically calibrated relationships presented here will be applied to quasar samples in forthcoming work.......An empirical relationship, of particular interest for studies of high redshift active galactic nuclei (AGNs) and quasars, between the masses of their central black-holes and rest-frame ultraviolet (UV) parameters measured in single-epoch AGN spectra is presented. This relationship is calibrated...

  17. Automated Determination of a Package's Center of Mass

    Directory of Open Access Journals (Sweden)

    Ayaz Hemani

    2010-01-01

    Full Text Available In order to address the issue of increased efficiency and better planning for parcel shipments, an automated computer program was developed in Microsoft Excel that calculates center of mass and moments of mass with greater speed and reliability than currently implemented systems. This simple program requires only a variable density function and limits of integration for a given object as input within the spreadsheet system. Once the required input has been provided, a series of chain calculations, with the help of a Visual Basic for Applications (VBA script, is able to process the input, which is done through integration and a Riemann sum. Furthermore, the foundation of the program can also be used for calculating other physical quantities of interest such as the moment of inertia or surface area of an object.

  18. Proposed Framework for Determining Added Mass of Orion Drogue Parachutes

    Science.gov (United States)

    Fraire, Usbaldo, Jr.; Dearman, James; Morris, Aaron

    2011-01-01

    The Crew Exploration Vehicle (CEV) Parachute Assembly System (CPAS) project is executing a program to qualify a parachute system for a next generation human spacecraft. Part of the qualification process involves predicting parachute riser tension during system descent with flight simulations. Human rating the CPAS hardware requires a high degree of confidence in the simulation models used to predict parachute loads. However, uncertainty exists in the heritage added mass models used for loads predictions due to a lack of supporting documentation and data. Even though CPAS anchors flight simulation loads predictions to flight tests, extrapolation of these models outside the test regime carries the risk of producing non-bounding loads. A set of equations based on empirically derived functions of skirt radius is recommended as the simplest and most viable method to test and derive an enhanced added mass model for an inflating parachute. This will increase confidence in the capability to predict parachute loads. The selected equations are based on those published in A Simplified Dynamic Model of Parachute Inflation by Dean Wolf. An Ames 80x120 wind tunnel test campaign is recommended to acquire the reefing line tension and canopy photogrammetric data needed to quantify the terms in the Wolf equations and reduce uncertainties in parachute loads predictions. Once the campaign is completed, the Wolf equations can be used to predict loads in a typical CPAS Drogue Flight test. Comprehensive descriptions of added mass test techniques from the Apollo Era to the current CPAS project are included for reference.

  19. Determining in vivo phosphorylation sites using mass spectrometry.

    Science.gov (United States)

    Breitkopf, Susanne B; Asara, John M

    2012-04-01

    Phosphorylation is the most studied protein post-translational modification (PTM) in biological systems, since it controls cell growth, proliferation, survival, and other processes. High-resolution/high mass accuracy mass spectrometers are used to identify protein phosphorylation sites due to their speed, sensitivity, selectivity, and throughput. The protocols described here focus on two common strategies: (1) identifying phosphorylation sites from individual proteins and small protein complexes, and (2) identifying global phosphorylation sites from whole-cell and tissue extracts. For the first, endogenous or epitope-tagged proteins are typically immunopurified from cell lysates, purified via gel electrophoresis or precipitation, and enzymatically digested into peptides. Samples can be optionally enriched for phosphopeptides using immobilized metal affinity chromatography (IMAC) or titanium dioxide (TiO(2)) and then analyzed by microcapillary liquid chromatography/tandem mass spectrometry (LC-MS/MS). Global phosphorylation site analyses that capture pSer/pThr/pTyr sites from biological sources sites are more resource and time consuming and involve digesting the whole-cell lysate, followed by peptide fractionation by strong cation-exchange chromatography, phosphopeptide enrichment by IMAC or TiO(2), and LC-MS/MS. Alternatively, the protein lysate can be fractionated by SDS-PAGE, followed by digestion, phosphopeptide enrichment, and LC-MS/MS. One can also immunoprecipitate only phosphotyrosine peptides using a pTyr antibody followed by LC-MS/MS.

  20. Flow Curve Determination at Large Plastic Strain Levels to Accurately Constitutive Equations of AHSS in Forming Simulation

    Science.gov (United States)

    Lemoine, X.; Sriram, S.; Kergen, R.

    2011-05-01

    ArcelorMittal continuously develops new steel grades (AHSS) with high performance for the automotive industry to improve the weight reduction and the passive safety. The wide market introduction of AHSS raises a new challenge for manufacturers in terms of material models in the prediction of forming—especially formability and springback. The relatively low uniform elongation, the high UTS and the low forming limit curve of these AHSS may cause difficulties in forming simulations. One of these difficulties is the consequence of the relatively low uniform elongation on the parameters identification of isotropic hardening model. Different experimental tests allow to reach large plastic strain levels (hydraulic bulge test, stack compression test, shear test…). After a description on how to determine the flow curve in these experimental tests, a comparison of the different flow curves is made for different steel grades. The ArcelorMittal identification protocol for hardening models is only based on stress-strain curves determined in uniaxial tension. Experimental tests where large plastic strain levels are reached are used to validate our identification protocol and to recommend some hardening models. Finally, the influence of isotropic hardening models and yield loci in forming prediction for AHSS steels will be presented.

  1. Accurate determination of the Gibbs energy of Cu-Zr melts using the thermodynamic integration method in Monte Carlo simulations

    Science.gov (United States)

    Harvey, J.-P.; Gheribi, A. E.; Chartrand, P.

    2011-08-01

    The design of multicomponent alloys used in different applications based on specific thermo-physical properties determined experimentally or predicted from theoretical calculations is of major importance in many engineering applications. A procedure based on Monte Carlo simulations (MCS) and the thermodynamic integration (TI) method to improve the quality of the predicted thermodynamic properties calculated from classical thermodynamic calculations is presented in this study. The Gibbs energy function of the liquid phase of the Cu-Zr system at 1800 K has been determined based on this approach. The internal structure of Cu-Zr melts and amorphous alloys at different temperatures, as well as other physical properties were also obtained from MCS in which the phase trajectory was modeled by the modified embedded atom model formalism. A rigorous comparison between available experimental data and simulated thermo-physical properties obtained from our MCS is presented in this work. The modified quasichemical model in the pair approximation was parameterized using the internal structure data obtained from our MCS and the precise Gibbs energy function calculated at 1800 K from the TI method. The predicted activity of copper in Cu-Zr melts at 1499 K obtained from our thermodynamic optimization was corroborated by experimental data found in the literature. The validity of the amplitude of the entropy of mixing obtained from the in silico procedure presented in this work was analyzed based on the thermodynamic description of hard sphere mixtures.

  2. [Determination of aflatoxins in cashew by high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Bi, Ruifeng; Fan, Zhixian; Fu, Meng

    2011-12-01

    A method for the determination of four aflatoxins in cashew using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The sample was extracted with methanol-water (8: 2, v/v) solution, followed by a cleanup procedure with Florisil column. The target compounds were eluted using 5 mL acetone-water-formic acid (96: 3.5:0.5, v/v/v) solution. The eluate was dried under N2, then dissolved in 1 mL methanol. Four aflatoxins were separated in MG C18 column (100 mm x 3.0 mm, 3 microm) adopting a gradient program within 15 min. A triple quadrupole mass spectrometry equipped with an electrospray ionization source operated in the positive ion mode was used to detect the aflatoxins. The good correlation coefficients (r2 > 0.997) of the four aflatoxins were obtained within their respective linear ranges. The limits of detection (S/N = 3) were between 0.009 microg/kg and 0.04 microg/kg, and the limits of quantification (S/N = 10) were between 0.03 microg/kg and 0.12 microg/kg. The recoveries were in a range of 63.0% -78.5% with the relative standard deviations (RSDs) varied from 2.8% to 9.1%. The validation results meet the requirements of trace assay. Matrix effects were estimated and the signal suppression/enhancement ranged from 88.8% to 99.4%. The results indicate that the developed method is simple, fast, accurate, and can be applied for the determination of fours aflatoxins in cashew.

  3. Accurate determination of lattice parameters based on Niggli reduced cell theory by using digitized electron diffraction micrograph.

    Science.gov (United States)

    Yang, Yi; Cai, Canying; Lin, Jianguo; Gong, Lunjun; Yang, Qibin

    2017-05-01

    In this paper, we used Niggli reduced cell theory to determine lattice constants of a micro/nano crystal by using electron diffraction patterns. The Niggli reduced cell method enhanced the accuracy of lattice constant measurement obviously, because the lengths and the angles of lattice vectors of a primitive cell can be measured directly on the electron micrographs instead of a double tilt holder. With the aid of digitized algorithm and least square optimization by using three digitized micrographs, a valid reciprocal Niggli reduced cell number can be obtained. Thus a reciprocal and real Bravais lattices are acquired. The results of three examples, i.e., Mg4Zn7, an unknown phase (Precipitate phase in nickel-base superalloy) and Ba4Ti13O30 showed that the maximum errors are 1.6% for lengths and are 0.3% for angles.

  4. A single-aliquot OSL protocol using bracketing regenerative doses to accurately determine equivalent doses in quartz

    CERN Document Server

    Folz, E

    1999-01-01

    In most cases, sediments show inherent heterogeneity in their luminescence behaviours and bleaching histories, and identical aliquots are not available: single-aliquot determination of the equivalent dose (ED) is then the approach of choice and the advantages of using regenerative protocols are outlined. Experiments on five laboratory bleached and dosed quartz samples, following the protocol described by Murray and Roberts (1998. Measurement of the equivalent dose in quartz using a regenerative-dose single aliquot protocol. Radiation Measurements 27, 171-184), showed the hazards of using a single regeneration dose: a 10% variation in the regenerative dose yielded some equivalent dose estimates that differed from the expected value by more than 5%. A protocol is proposed that allows the use of different regenerative doses to bracket the estimated equivalent dose. The measured ED is found to be in excellent agreement with the known value when the main regeneration dose is within 10% of the true equivalent dose.

  5. Effective Temperatures of Selected Main-Sequence Stars with the Most Accurate Parameters

    Science.gov (United States)

    Soydugan, F.; Eker, Z.; Soydugan, E.; Bilir, S.; Gökçe, E. Y.; Steer, I.; Tüysüz, M.; Šenyüz, T.; Demircan, O.

    2015-07-01

    In this study we investigate the distributions of the properties of detached double-lined binaries (DBs) in the mass-luminosity, mass-radius, and mass-effective temperature diagrams. We have improved the classical mass-luminosity relation based on the database of DBs by Eker et al. (2014a). Based on the accurate observational data available to us we propose a method for improving the effective temperatures of eclipsing binaries with accurate mass and radius determinations.

  6. Determining Central Black Hole Masses in Distant Active Galaxies

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2002-01-01

    An empirical relationship, of particular interest for studies of high redshift active galactic nuclei (AGNs) and quasars, between the masses of their central black-holes and rest-frame ultraviolet (UV) parameters measured in single-epoch AGN spectra is presented. This relationship is calibrated...... black-hole demographics at high redshift as well as to statistically study the fundamental properties of AGNs. The broad line region size - luminosity relationship is key to the calibrations presented here. The fact that its intrinsic scatter is also the main source of uncertainty in the calibrations...

  7. Higher order and heavy quark mass effects in the determination of parton distribution functions

    Energy Technology Data Exchange (ETDEWEB)

    Bertone, Valerio

    2013-07-01

    The present thesis was devoted to the study of the inclusion of higher-order corrections and heavy quark mass effects in a PDF determination. This has been carried out in the NNPDF framework resulting originally in the NNPDF2.1 sets, which were at a later stage supplemented by the first LHC data leading to the most recent NNPDF2.3 sets. In Chapter 1 the concept of Parton Distribution Function (PDF) was introduced. We have shown how the analytical computation of the Deep-Inelastic-Scattering (DIS) process at order α{sub s} in QCD leads to initial-stale collinear divergences which, using the factorization theorem, can be reabsorbed into the PDFs. The energy dependence of PDFs is fully determined and the task is then reduced to the determination of the x (Bjorken variable) dependence. In Chapter 2 a detailed discussion of the factorization schemes presently available to include heavy quark mass effects into DIS structure functions has been given. It emerged that there are two possible basic approaches to the calculation of the DIS structure functions. In the first approach, the so-called Fixed-Flavour-Number Scheme (FFNS), the calculation is performed retaining the quark mass of the heavy flavours which provide a ''natural'' regulator for the infrared divergences. In the second approach, called Zero-Mass Variable-Flavour-Number Scheme (ZM-VFNS), the heavy quark masses are instead set to zero and this gives rise to the usual final-state collinear divergences that are absorbed into the PDFs. In addition, in the ZM-VFNS, the number of active flavours is assumed to increase by one unity as the energy of the process crosses the energy threshold of a given heavy quark. In order to obtain a factorization scheme that is accurate both at large and low energies, several prescriptions that interpolate between FFNS at low energy and ZM-VFNS at large energy have been proposed and implemented in as many PDF fits. In Chapter 2 they have been described showing

  8. Dark matter haloes determine the masses of supermassive black holes

    CERN Document Server

    Booth, C M

    2009-01-01

    The energy and momentum deposited by the radiation from accretion onto the supermassive black holes (BHs) that reside at the centres of virtually all galaxies can halt or even reverse gas inflow, providing a natural mechanism for supermassive BHs to regulate their growth and to couple their properties to those of their host galaxies. However, it remains unclear whether this self-regulation occurs on the scale at which the BH is gravitationally dominant, on that of the stellar bulge, the galaxy, or that of the entire dark matter halo. To answer this question, we use self-consistent simulations of the co-evolution of the BH and galaxy populations that reproduce the observed correlations between the masses of the BHs and the properties of their host galaxies. We first confirm unambiguously that the BHs regulate their growth: the amount of energy that the BHs inject into their surroundings remains unchanged when the fraction of the accreted rest mass energy that is injected, is varied by four orders of magnitude....

  9. Determination of representative renal depth for accurate attenuation corred in measurement of glomerular filtration rate in transplanted kidney

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Soon Nam; Kim, Sung Hoon; Rha, Sung Eun; Chung, Yong An; Yoo, Ie Ryung; Sohn, Hyung Sun; Lee, Sung Young; Chung, Soo Kyo [The Catholic Univ. of Korea, Seoul (Korea, Republic of)

    2002-08-01

    To measure reliable glomerular filtration rate by using the representative values of transplanted renal depths, which are measured with ultrasonography. We included 54 patients (26 men, 28 women), with having both renal scintigraphy and ultrasonography after renal transplantation. We measured DFR with Gates' method using the renal depth measured by ultrasonography, and median and mean ones in each patient. We compared GFR derived from ultrasonography-measured renal depth with GFR derived from median and mean renal depths. The correlation coefficients were obtained among GFR derived from ultrasonography-measured renal depths, median and mean renal depth under linear regression analysis. We determined whether GFR derived from median or mean renal depth could substitute GFR derived from ultrasonography-measured renal depth with Bland-Altman method. We analyze the expected errors of the GFR using representative renal depth in terms of age, sex, weight, height, creatinine value, and body surface. The transplanted renal depths range from 3.20 cm to 5.96 cm. The mean value and standard deviation of renal depths measured by ultrasonography are 4.09{+-}0.65 cm in men, and 4.24{+-}0.78 cm in women. The median value of renal depths measured by ultrasonography is 4.36 cm in men and 4.14 cm in women. The GFR derived from median renal depth is more consistent with GFR derived from ultrasonography-measured renal depth than GFR derived from mean renal depth. Differences of GFR derived from median and ultrasonography-measured renal depth are not significantly different in the groups classified with creatinine value, age, sex, height, weight and body surface. When median value is adapted as a representative renal depth, we could obtain reliable GFR in transplanted kidney simply.

  10. Determination of the Relative Atomic Masses of Metals by Liberation of Molecular Hydrogen

    Science.gov (United States)

    Waghorne, W. Earle; Rous, Andrew J.

    2009-01-01

    Students determine the relative atomic masses of calcium, magnesium, and aluminum by reaction with hydrochloric acid and measurement of the volume of hydrogen gas liberated. The experiment demonstrates stoichiometry and illustrates clearly that mass of the reagent is not the determinant of the amounts in chemical reactions. The experiment is…

  11. Mass and position determination of attached particles on cantilever based mass sensors

    DEFF Research Database (Denmark)

    Dohn, Søren; Svendsen, Winnie Edith; Boisen, Anja;

    2007-01-01

    modes. This finding is verified experimentally using a microscale cantilever with and without an attached gold bead. The resonant frequencies of several bending modes are measured as a function of the bead position. The bead mass and position calculated from the measured resonant frequencies are in good...

  12. A High Resolution/Accurate Mass (HRAM) Data-Dependent MS3 Neutral Loss Screening, Classification, and Relative Quantitation Methodology for Carbonyl Compounds in Saliva

    Science.gov (United States)

    Dator, Romel; Carrà, Andrea; Maertens, Laura; Guidolin, Valeria; Villalta, Peter W.; Balbo, Silvia

    2016-10-01

    Reactive carbonyl compounds (RCCs) are ubiquitous in the environment and are generated endogenously as a result of various physiological and pathological processes. These compounds can react with biological molecules inducing deleterious processes believed to be at the basis of their toxic effects. Several of these compounds are implicated in neurotoxic processes, aging disorders, and cancer. Therefore, a method characterizing exposures to these chemicals will provide insights into how they may influence overall health and contribute to disease pathogenesis. Here, we have developed a high resolution accurate mass (HRAM) screening strategy allowing simultaneous identification and relative quantitation of DNPH-derivatized carbonyls in human biological fluids. The screening strategy involves the diagnostic neutral loss of hydroxyl radical triggering MS3 fragmentation, which is only observed in positive ionization mode of DNPH-derivatized carbonyls. Unique fragmentation pathways were used to develop a classification scheme for characterizing known and unanticipated/unknown carbonyl compounds present in saliva. Furthermore, a relative quantitation strategy was implemented to assess variations in the levels of carbonyl compounds before and after exposure using deuterated d 3 -DNPH. This relative quantitation method was tested on human samples before and after exposure to specific amounts of alcohol. The nano-electrospray ionization (nano-ESI) in positive mode afforded excellent sensitivity with detection limits on-column in the high-attomole levels. To the best of our knowledge, this is the first report of a method using HRAM neutral loss screening of carbonyl compounds. In addition, the method allows simultaneous characterization and relative quantitation of DNPH-derivatized compounds using nano-ESI in positive mode.

  13. Tumor volume in subcutaneous mouse xenografts measured by microCT is more accurate and reproducible than determined by 18F-FDG-microPET or external caliper

    Directory of Open Access Journals (Sweden)

    Jørgensen Jesper

    2008-10-01

    Full Text Available Abstract Background In animal studies tumor size is used to assess responses to anticancer therapy. Current standard for volumetric measurement of xenografted tumors is by external caliper, a method often affected by error. The aim of the present study was to evaluate if microCT gives more accurate and reproducible measures of tumor size in mice compared with caliper measurements. Furthermore, we evaluated the accuracy of tumor volume determined from 18F-fluorodeoxyglucose (18F-FDG PET. Methods Subcutaneously implanted human breast adenocarcinoma cells in NMRI nude mice served as tumor model. Tumor volume (n = 20 was determined in vivo by external caliper, microCT and 18F-FDG-PET and subsequently reference volume was determined ex vivo. Intra-observer reproducibility of the microCT and caliper methods were determined by acquiring 10 repeated volume measurements. Volumes of a group of tumors (n = 10 were determined independently by two observers to assess inter-observer variation. Results Tumor volume measured by microCT, PET and caliper all correlated with reference volume. No significant bias of microCT measurements compared with the reference was found, whereas both PET and caliper had systematic bias compared to reference volume. Coefficients of variation for intra-observer variation were 7% and 14% for microCT and caliper measurements, respectively. Regression coefficients between observers were 0.97 for microCT and 0.91 for caliper measurements. Conclusion MicroCT was more accurate than both caliper and 18F-FDG-PET for in vivo volumetric measurements of subcutaneous tumors in mice.18F-FDG-PET was considered unsuitable for determination of tumor size. External caliper were inaccurate and encumbered with a significant and size dependent bias. MicroCT was also the most reproducible of the methods.

  14. Non-targeted screening for contaminants in paper and board food-contact materials using effect-directed analysis and accurate mass spectrometry

    DEFF Research Database (Denmark)

    Bengtström, Linda; Rosenmai, Anna Kjerstine; Trier, Xenia

    2016-01-01

    Due to large knowledge gaps in chemical composition and toxicological data for substances involved, paper and board food-contact materials (P&B FCM) have been emerging as a FCM type of particular concern for consumer safety. This study describes the development of a step-by-step strategy, including...... extraction, high-performance liquid chromatography (HPLC) fractionation, tentative identification of relevant substances and in vitro testing of selected tentatively identified substances. As a case study, we used two fractions from a recycled pizza box sample which exhibited aryl hydrocarbon receptor (Ah......R) activity. These fractions were analysed by gas chromatography (GC) and ultra-HPLC (UHPLC) coupled to quadrupole time-of-flight mass spectrometers (QTOF MS) in order tentatively to identify substances. The elemental composition was determined for peaks above a threshold, and compared with entries...

  15. Liquid chromatography quadrupole time-of-flight mass spectrometry selective determination of ochratoxin A in wine.

    Science.gov (United States)

    Rodríguez-Cabo, T; Rodríguez, I; Ramil, M; Cela, R

    2016-05-15

    The performance of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) for ochratoxin A (OTA) determination in wine is evaluated for the first time. Sample preparation was optimized to obtain quantitative recoveries at the same time that the efficiency of electrospray ionization (ESI) remained unaltered between sample extracts and calibration standards. Under final conditions, samples (20 mL) were concentrated using a reversed-phase solid-phase extraction (SPE) cartridge, followed by OTA elution with 1 mL of ethyl acetate. The absolute recoveries of the method, established against calibration standards, were 91-121% and 90-113% (without and with internal standard correction, respectively), for wines fortified at 3 concentration levels. The attained LOQ (0.05 ng mL(-1)) remained below the maximum permitted OTA concentration (2 ng mL(-1)) in dry wines. The method was applied to different samples, with OTA being found in some dessert wines at concentrations below 1 ng mL(-1). The ethyl ester of OTA (OTC) could be identified in the same wine samples from its accurate full product ion spectra.

  16. Capillary ion chromatography-mass spectrometry for simultaneous determination of glucosylglycerol and sucrose in intracellular extracts of cyanobacteria.

    Science.gov (United States)

    Fa, Yun; Liang, Wenhui; Cui, He; Duan, Yangkai; Yang, Menglong; Gao, Jun; Liu, Huizhou

    2015-09-15

    A capillary ion chromatography-mass spectrometry (MS) method was proposed to determine glucosylglycerol (GG), sucrose, and five other carbohydrates. MS conditions and make-up flow parameters were optimized. This method is accurate and sensitive for simultaneous analysis of carbohydrates, with mean correlation coefficients of determination greater than 0.99, relative standard deviation of 0.91-2.81% for eight replicates, and average spiked recoveries of 97.3-104.9%. Limits of detection of sodium adduct were obtained with MS detection in selected ion mode for GG (0.006mg/L), sucrose (0.02mg/L), and other carbohydrates (0.03mg/L). This method was successfully applied to determine GG and sucrose in intracellular extracts of salt-stressed cyanobacteria.

  17. Tumor volume in subcutaneous mouse xenografts measured by microCT is more accurate and reproducible than determined by 18F-FDG-microPET or external caliper

    DEFF Research Database (Denmark)

    Jensen, Mette Munk; Jørgensen, Jesper Tranekjaer; Binderup, Tina;

    2008-01-01

    and reproducible measures of tumor size in mice compared with caliper measurements. Furthermore, we evaluated the accuracy of tumor volume determined from 18F-fluorodeoxyglucose (18F-FDG) PET. METHODS: Subcutaneously implanted human breast adenocarcinoma cells in NMRI nude mice served as tumor model. Tumor volume...... systematic bias compared to reference volume. Coefficients of variation for intra-observer variation were 7% and 14% for microCT and caliper measurements, respectively. Regression coefficients between observers were 0.97 for microCT and 0.91 for caliper measurements. CONCLUSION: MicroCT was more accurate...

  18. Mass loss rate determinations of southern OB stars

    CERN Document Server

    Benaglia, P; Koribalski, B S

    2001-01-01

    A sample of OB stars (eleven Of, one O and one B supergiant) has been surveyed with the Australia Telescope Compact Array at 4.8 and 8.64 GHz with a resolution of 2'' -- 4''. Five stars were detected; three of them have negative spectral indices, consistent with non-thermal emission, and two have positive indices. The thermal radiation from HD 150135 and HD 163181 can be explained as coming from an optically thick ionized stellar wind. The non-thermal radiation from CD-47 4551, HD 124314 and HD 150136 possibly comes from strong shocks in the wind itself and/or in the wind colliding region if the stars have a massive early-type companion. The percentage of non-thermal emitters among detected O stars has increased up to ~50%. The Of star HD 124314 clearly shows flux density variations. Mass loss rates (or upper limits) were derived for all the observed stars and the results compared with non-radio measurements and theoretical predictions.

  19. Glucose tolerance in obese pregnant women determines newborn fat mass

    DEFF Research Database (Denmark)

    Carlsen, Emma Malchau; Renault, Kristina Martha; Nørgaard, Kirsten

    2016-01-01

    : Among 264 term, healthy, and singleton infants eligible for inclusion, 248 were included. Of these 205 (83%) obese mother-newborn-dyads had a DXA scan and 2-h plasma glucose measurements. Linear regression analysis showed that birth weight z-scores correlated with 2-h plasma glucose levels (p = 0......INTRODUCTION: Offspring of obese women have both short- and long-term increased morbidities. We investigated the relationship between maternal 2-h plasma glucose level determined by oral glucose tolerance test, degree of obesity, gestational weight gain and total fat, abdominal fat, and fat...

  20. Oxygen mass transfer and hydrodynamic behaviour in wastewater: determination of local impact of surfactants by visualization techniques.

    Science.gov (United States)

    Jimenez, Mélanie; Dietrich, Nicolas; Grace, John R; Hébrard, Gilles

    2014-07-01

    Powerful techniques, based on the Planar Laser Induced Fluorescence (PLIF) technique, are deployed to locally visualize and quantify the impact of surfactants in wastewaters on hydrodynamics and oxygen mass transfer. Bubble diameter, aspect ratio, rise velocity, contamination angle, as well as flux, flux density, liquid side mass transfer and diffusion coefficients of transferred oxygen are determined based on these techniques applied in the wake of rising bubbles of diameter 1 mm and through planar gas/liquid interfaces. The initial experiments were performed in demineralized water containing small amounts of surfactant. Different concentrations of surfactant were added to finally reach the Critical Micelle Concentration (CMC). Bubbles have classically been found to be more spherical with a reduced rise velocity in the presence of surfactants up to the CMC. Above the CMC, these hydrodynamic characteristics were found to be almost constant, although the oxygen mass transfer decreased due to the presence of surfactants. Experimental results were markedly lower than predicted by the well-known Frössling equation with rigid surfaces. This is believed to be caused by a barrier of surfactants hindering the oxygen mass transfer at the interface. Similar hindrance of oxygen mass transfer applies to waters from sewage plants (filtered raw water and treated water), making accurate design of aeration tanks difficult.

  1. Determination of vanillin, ethyl vanillin, and coumarin in infant formula by liquid chromatography-quadrupole linear ion trap mass spectrometry.

    Science.gov (United States)

    Shen, Yan; Han, Chao; Liu, Bin; Lin, Zhengfeng; Zhou, Xiujin; Wang, Chengjun; Zhu, Zhenou

    2014-02-01

    A simple, precise, accurate, and validated liquid chromatography-quadrupole linear ion trap mass spectrometry method was developed for the determination of vanillin, ethyl vanillin, and coumarin in infant formula samples. Following ultrasonic extraction with methanol/water (1:1, vol/vol), and clean-up on an HLB solid-phase extraction cartridge (Waters Corp., Milford, MA), samples were separated on a Waters XSelect HSS T3 column (150 × 2.1-mm i.d., 5-μm film thickness; Waters Corp.), with 0.1% formic acid solution-acetonitrile as mobile phase at a flow rate of 0.25 mL/min. Quantification of the target was performed by the internal standard approach, using isotopically labeled compounds for each chemical group, to correct matrix effects. Data acquisition was carried out in multiple reaction monitoring transitions mode, monitoring 2 multiple reaction monitoring transitions to ensure an accurate identification of target compounds in the samples. Additional identification and confirmation of target compounds were performed using the enhanced product ion modus of the linear ion trap. The novel liquid chromatography-quadrupole linear ion trap mass spectrometry platform offers the best sensitivity and specificity for characterization and quantitative determination of vanillin, ethyl vanillin, and coumarin in infant formula and fulfills the quality criteria for routine laboratory application.

  2. New method for precise determination of top quark mass at LHC

    CERN Document Server

    Kawabata, Sayaka

    2014-01-01

    A new method to measure the mass of the top quark at the LHC is presented. This method uses lepton energy distribution and ideally does not depend on the velocity distribution of the top quark. We perform a simulation analysis of the top quark mass reconstruction using this method at the leading order, taking account of experimental circumstances. We estimate the sensitivity of the mass determination. The results show that this method is viable in realistic experimental conditions and has a possibility to achieve a good accuracy in determining a theoretically well-defined top quark mass by including higher-order corrections.

  3. Simultaneous determination of cocaine and opiates in dried blood spots by electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Antelo-Domínguez, Ángel; Cocho, José Ángel; Tabernero, María Jesús; Bermejo, Ana María; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

    2013-12-15

    A sample pre-treatment method based on blood spot collection filter cards was optimized as a means of using small volume samples for the screening and confirmation of cocaine and opiates abuse. Dried blood spots (DBSs) were prepared by dispersing 20 µL of whole blood specimens previously mixed with the internal standards (deuterated analogs of each target), and subjecting the whole DBS to extraction with 5 mL of methanol under orbital-horizontal shaking (180 rpm) for 10 min. Determinations were based on direct electrospray ionization tandem mass spectrometry (ESI-MS/MS) by injecting the re-dissolved methanol extract with the delivery solution (acetonitrile-water-formic acid, 80:19.875:0.125) at a flow rate of 60 µL min(-1), and using multiple reaction monitoring (MRM) mode with the m/z (precursor ion)→m/z (product ion) transitions for acquisition. Matrix effect has been found to be statistically significant (Multiple Range Test) when assessing cocaine, BZE, codeine and morphine, and the use of the standard addition method (dispersion of whole blood previously mixed with standards onto the filter papers) was needed for accurate determinations. The developed DBS-ESI-MS/MS procedure offered good intra-day and inter-day precisions (lower than 10% and 12%, respectively), as well as good intra-day and inter-day accuracies (inter-day absolute recoveries, expressed as the mean analytical recovery over three target concentration levels, of 103%, 100%, 101%, 98% and 100% for cocaine, BZE, codeine, morphine and 6-MAM, respectively). The high sensitivity inherent to MS/MS determinations combined with the minimal dilution of sample allowed low limits of quantification for all targets, and the developed method results therefore adequate for cocaine and opiates screening and confirmation purposes. The procedure was finally applied to DBSs prepared from whole blood from polydrug abusers, and results were compared with those obtained after a conventional sample pretreatment

  4. Direct determination of mercury in cosmetic samples by isotope dilution inductively coupled plasma mass spectrometry after dissolution with formic acid

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Ying; Shi, Zeming; Zong, Qinxia; Wu, Peng; Su, Jing [Sichuan Provincial Key Laboratory of Nuclear Technology in Geology, College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu 610059 (China); Liu, Rui, E-mail: liur.ray@gmail.com [Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institutions, College of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China)

    2014-02-17

    Graphical abstract: -- Highlights: •Simple, sensitive, and accurate method is established for mercury determination in cosmetics. •The sample preparation procedure is highly simplified. •Isotope dilution efficiently eliminates matrix effect. •First report of using formic acid based method in combination with PVG-ID-ICP MS for mercury quantitation in cosmetics. -- Abstract: A new method was proposed for the accurate determination of mercury in cosmetic samples based on isotopic dilution (ID)-photochemical vapor generation (PVG)-inductively coupled plasma mass spectrometry (ICP MS) measurement. Cosmetic samples were directly dissolved in formic acid solution and subsequently subjected to PVG for the reduction of mercury into vapor species following by ICP MS detection. Therefore, the risks of analyte contamination and loss were avoided. Highly enriched {sup 201}Hg isotopic spike is added to cosmetics and the isotope ratios of {sup 201}Hg/{sup 202}Hg were measured for the quantitation of mercury. With ID calibration, the influences originating from sample matrixes for the determination of mercury in cosmetic samples have been efficiently eliminated. The effects of several experimental parameters, such as the concentration of the formic acid, and the flow rates of carrier gas and sample were investigated. The method provided good reproducibility and the detection limits were found to be 0.6 pg mL{sup −1}. Finally, the developed method was successfully applied for the determination of mercury in six cosmetic samples and a spike test was performed to verify the accuracy of the method.

  5. High Performance Liquid Chromatography Tandem Mass Spectrometry Assay for the Determination of Cobinamide in Pig Plasma

    Science.gov (United States)

    McCracken, Brent A.; Brittain, Matthew K.

    2015-01-01

    Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been widely utilized for the analysis of compounds in biological matrices due to its selectivity and sensitivity. This study describes the application of an LC-MS/MS-based approach toward the analysis of cobinamide in Yorkshire pig plasma. The selectivity, accuracy, precision, recovery, linearity, range, carryover, sensitivity, matrix effect, interference, stability, reproducibility, and ruggedness of the method were investigated in pig plasma. The accuracy and precision of the method was determined to be within 10% over three different days over a range of concentrations (25–10,000 ng/mL) that spanned more than two orders of magnitude. The lower limit of quantitation (LLOQ) for dicyanocobinamide was determined to be 25 ng/mL in pig plasma. Carryover was acceptable, as the area response of the carryover blanks were ≤15% of the area response of the nearest LLOQ standard for the analyte, while it was nonexistent for the internal standard. Specificity was ensured using six different lots of pig plasma. While the matrix effects of dicyanocobinamide in plasma were enhanced, ginsenoside Rb1 experienced signal suppression under the described conditions. The absolute recovery results for both compounds were consistent, precise, and reproducibly lower than expected at ~60% for dicyanocobinamide and ~22% for ginsenoside Rb1, confirming that a matrix standard curve was required for accurate quantitation. Cobinamide was shown to be very stable in matrix at various storage conditions including room temperature, refrigerated, and frozen at time intervals of 20 hours, 4 days, and 60 days respectively. This method was demonstrated to be sensitive, reproducible, stable, and rugged, and it should be applicable to the analysis of cobinamide in other biological matrices and species. PMID:26540437

  6. Gas chromatography–triple quadrupole mass spectrometry for the determination of atmospheric polychlorinated naphthalenes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Fang [Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Jin, Jing [Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023 (China); Sun, Xiaoli [Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Xueli; Li, Yun; Shah, Syed Mazhar [Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023 (China); Chen, Jiping, E-mail: chenjp@dicp.ac.cn [Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023 (China)

    2014-09-15

    Highlights: • Atmospheric PCNs were detected by isotope-dilution GC–MS/MS. • The pollution levels of PCNs covering from mono- to octa-CNs were investigated comprehensively in air samples. • The dioxin-like toxicity and human exposure levels of PCNs in air samples were estimated. - Abstract: Atmospheric polychlorinated naphthalenes (PCNs) ranging from mono-CNs to octa-CNs were detected using isotope-dilution gas chromatography coupled with triple quadrupole mass spectrometry (GC–MS/MS). The developed instrumental method was successfully applied to the determination of PCNs in technical products. It was observed that there were significant differences in concentrations, homologue profiles, chlorinated contents and total toxic equivalents (∑TEQs) of PCNs for four Halowax products. Subsequently, the validation of the analytical method was evaluated for the determination of PCNs in air samples in terms of method detection limit (MDL), recovery and matrix effect. The results demonstrated that this method could provide satisfactory sensitivity and adequate selectivity with lower cost. It was conducted to comprehensively evaluate the levels, composition patterns, ∑TEQs, and daily intake exposure of PCNs in indoor and outdoor air samples. Concentrations and ∑TEQs of PCNs in air samples ranged 47.7–832.7 pg m{sup −3} and 1.31–5.99 fg m{sup −3}, respectively, and the predominant homologues were di- and tri-CNs in the gas phase. The results indicated that this analytical method was useful for the accurate and specific evaluation of dioxin-like toxicity and human exposure levels of PCNs in the atmosphere.

  7. Measurement uncertainty for the determination of amphetamines in urine by liquid-phase microextraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Franco de Oliveira, Sarah Carobini Werner de Souza Eller; Yonamine, Mauricio

    2016-08-01

    A gas chromatography-mass spectrometry method for the determination of amphetamines in urine samples by means of liquid-phase microextraction was validated, including calculation of measurement uncertainty. After extraction in the three-phase mode, acceptor phase was withdrawn from the fiber and the residue was derivatized with trifluoroacetic anhydride. The method showed to be very simple, rapid and it required a significantly low amount of organic solvent for extraction. The limits of detection were 10 and 20μg/L for amphetamine and methamphetamine, respectively. The calibration curves were linear over the specified range (20μg/L to 1400μg/L; r(2)>0.99). The method showed to be both precise and accurate and a relative combined uncertainty of 2% was calculated. In order of importance, the factors which were more determinant for the calculation of method uncertainty were: analyte concentration, sample volume, trueness and method precision.

  8. An Automated High-Throughput Metabolic Stability Assay Using an Integrated High-Resolution Accurate Mass Method and Automated Data Analysis Software

    Science.gov (United States)

    Shah, Pranav; Kerns, Edward; Nguyen, Dac-Trung; Obach, R. Scott; Wang, Amy Q.; Zakharov, Alexey; McKew, John; Simeonov, Anton; Hop, Cornelis E. C. A.

    2016-01-01

    Advancement of in silico tools would be enabled by the availability of data for metabolic reaction rates and intrinsic clearance (CLint) of a diverse compound structure data set by specific metabolic enzymes. Our goal is to measure CLint for a large set of compounds with each major human cytochrome P450 (P450) isozyme. To achieve our goal, it is of utmost importance to develop an automated, robust, sensitive, high-throughput metabolic stability assay that can efficiently handle a large volume of compound sets. The substrate depletion method [in vitro half-life (t1/2) method] was chosen to determine CLint. The assay (384-well format) consisted of three parts: 1) a robotic system for incubation and sample cleanup; 2) two different integrated, ultraperformance liquid chromatography/mass spectrometry (UPLC/MS) platforms to determine the percent remaining of parent compound, and 3) an automated data analysis system. The CYP3A4 assay was evaluated using two long t1/2 compounds, carbamazepine and antipyrine (t1/2 > 30 minutes); one moderate t1/2 compound, ketoconazole (10 < t1/2 < 30 minutes); and two short t1/2 compounds, loperamide and buspirone (t½ < 10 minutes). Interday and intraday precision and accuracy of the assay were within acceptable range (∼12%) for the linear range observed. Using this assay, CYP3A4 CLint and t1/2 values for more than 3000 compounds were measured. This high-throughput, automated, and robust assay allows for rapid metabolic stability screening of large compound sets and enables advanced computational modeling for individual human P450 isozymes. PMID:27417180

  9. Determination of selenium in urine by inductively coupled plasma mass spectrometry: interferences and optimization

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Jons, O.

    1999-01-01

    and different salts on four selenium isotopes were examined. It was concluded that only Se-82 was usable for quantitative determination in urine as the blank at mass 82 was close to zero. The blank values at masses 76, 77 and 78 varied considerably and differently with different salts and salt concentrations...

  10. Spectrophotometric Determination of Trace Chromium(Ⅵ)in Mass Chromium(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The method for the sepration and determination of trace Cr(Ⅵ) exiting in mass Cr(Ⅲ)has been researched. The method is highly sensitive and less interference, but is simple and useful for analysis trace Cr(Ⅵ).

  11. Determination of Uranium and Plutonium Concentration in 1AF by Isotopic Dilution Mass Spectrometry Methods

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>It is important data to measure uranium and plutonium concentration for the reprocessing plant control analysis. The determination of uranium and plutonium concentration in 1AF by isotopic dilution mass

  12. Evaluation of comprehensive two-dimensional gas chromatography with accurate mass time-of-flight mass spectrometry for the metabolic profiling of plant-fungus interaction in Aquilaria malaccensis.

    Science.gov (United States)

    Wong, Yong Foo; Chin, Sung-Tong; Perlmutter, Patrick; Marriott, Philip J

    2015-03-27

    To explore the possible obligate interactions between the phytopathogenic fungus and Aquilaria malaccensis which result in generation of a complex array of secondary metabolites, we describe a comprehensive two-dimensional gas chromatography (GC × GC) method, coupled to accurate mass time-of-flight mass spectrometry (TOFMS) for the untargeted and comprehensive metabolic profiling of essential oils from naturally infected A. malaccensis trees. A polar/non-polar column configuration was employed, offering an improved separation pattern of components when compared to other column sets. Four different grades of the oils displayed quite different metabolic patterns, suggesting the evolution of a signalling relationship between the host tree (emergence of various phytoalexins) and fungi (activation of biotransformation). In total, ca. 550 peaks/metabolites were detected, of which tentative identification of 155 of these compounds was reported, representing between 20.1% and 53.0% of the total ion count. These are distributed over the chemical families of monoterpenic and sesquiterpenic hydrocarbons, oxygenated monoterpenes and sesquiterpenes (comprised of ketone, aldehyde, oxide, alcohol, lactone, keto-alcohol and diol), norterpenoids, diterpenoids, short chain glycols, carboxylic acids and others. The large number of metabolites detected, combined with the ease with which they are located in the 2D separation space, emphasises the importance of a comprehensive analytical approach for the phytochemical analysis of plant metabolomes. Furthermore, the potential of this methodology in grading agarwood oils by comparing the obtained metabolic profiles (pattern recognition for unique metabolite chemical families) is discussed. The phytocomplexity of the agarwood oils signified the production of a multitude of plant-fungus mediated secondary metabolites as chemical signals for natural ecological communication. To the best of our knowledge, this is the most complete

  13. Comments on the determination of the neutrino mass ordering in reactor neutrino experiments

    CERN Document Server

    Bilenky, S M

    2016-01-01

    We consider the problem of determination of the neutrino mass ordering via precise study of the vacuum neutrino oscillations in the JUNO and other future medium baseline reactor neutrino experiments. We are proposing to resolve neutrino mass ordering by determination of the neutrino oscillation parameters from analysis of the data of the reactor experiments and comparison them with the oscillation parameters obtained from analysis of the solar and KamLAND experiments.

  14. Using gravimetric measurement for determination of the mass fraction PM10

    Directory of Open Access Journals (Sweden)

    Nicolae Chirilă

    2011-12-01

    Full Text Available In this paper, we tried to determinate the air pollution level with mass fraction PM10 from Targu Mures area. For this purpose, determinations were made in University Petru Maior’s laboratory, using ADR 1200 S device and in Targu Mures Environmental Department’s laboratory. The results that we obtained show a low level of air pollution with mass fraction PM10 in Targu Mures area.

  15. Fast and accurate determination of the relative binding affinities of small compounds to HIV-1 protease using non-equilibrium work.

    Science.gov (United States)

    Ngo, Son Tung; Hung, Huynh Minh; Nguyen, Minh Tho

    2016-12-05

    The fast pulling ligand (FPL) out of binding cavity using non-equilibrium molecular dynamics (MD) simulations was demonstrated to be a rapid, accurate and low CPU demand method for the determination of the relative binding affinities of a large number of HIV-1 protease (PR) inhibitors. In this approach, the ligand is pulled out of the binding cavity of the protein using external harmonic forces, and the work of pulling force corresponds to the relative binding affinity of HIV-1 PR inhibitor. The correlation coefficient between the pulling work and the experimental binding free energy of R=-0.95 shows that FPL results are in good agreement with experiment. It is thus easier to rank the binding affinities of HIV-1 PR inhibitors, that have similar binding affinities because the mean error bar of pulling work amounts to δW=7%. The nature of binding is discovered using the FPL approach. © 2016 Wiley Periodicals, Inc.

  16. Numerical method to determine mechanical parameters of engineering design in rock masses

    Institute of Scientific and Technical Information of China (English)

    薛廷河; 项贻强; 郭发忠

    2004-01-01

    This paper proposes a new continuity model for engineering in rock masses and a new schematic method for reporting the engineering of rock continuity. This method can be used to evaluate the mechanics of every kind of medium;and is a new way to determine the mechanical parameters used in engineering design in rock masses. In the numerical simulation, the experimental parameters of intact rock were combined with the structural properties of field rock. Theexperimental results for orthogonally-jointed rock are given. The results included the curves of the stress-strain relationship of some rock masses, the curve of the relationship between the dimension Δ and the uniaxial pressure-resistant strength σc of these rock masses, and pictures of the destructive procedure of some rock masses in uniaxial or triaxial tests, etc. Application of the method to engineering design in rock masses showed the potential of its application to engineering practice.

  17. Numerical method to determine mechanical parameters of engineering design in rock masses.

    Science.gov (United States)

    Xue, Ting-He; Xiang, Yi-Qiang; Guo, Fa-Zhong

    2004-07-01

    This paper proposes a new continuity model for engineering in rock masses and a new schematic method for reporting the engineering of rock continuity. This method can be used to evaluate the mechanics of every kind of medium; and is a new way to determine the mechanical parameters used in engineering design in rock masses. In the numerical simulation, the experimental parameters of intact rock were combined with the structural properties of field rock. The experimental results for orthogonally-jointed rock are given. The results included the curves of the stress-strain relationship of some rock masses, the curve of the relationship between the dimension Delta and the uniaxial pressure-resistant strength sc of these rock masses, and pictures of the destructive procedure of some rock masses in uniaxial or triaxial tests, etc. Application of the method to engineering design in rock masses showed the potential of its application to engineering practice.

  18. The mass angular scattering power method for determining the kinetic energies of clinical electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Blais, N.; Podgorsak, E.B. (Montreal General Hospital, PQ (Canada). Dept. of Medical Physics)

    1992-10-01

    A method for determining the kinetic energy of clinical electron beams is described, based on the measurement in air of the spatial spread of a pencil electron beam which is produced from the broad clinical electron beam. As predicted by the Fermi-Eyges theory, the dose distribution measured in air on a plane, perpendicular to the incident direction of the initial pencil electron beam, is Gaussian. The square of its spatial spread is related to the mass angular scattering power which in turn is related to the kinetic energy of the electron beam. The measured spatial spread may thus be used to determine the mass angular scattering power, which is then used to determine the kinetic energy of the electron beam from the known relationship between mass angular scattering power and kinetic energy. Energies obtained with the mass angular scattering power method agree with those obtained with the electron range method. (author).

  19. Structure determination of adipokinetic hormones using fast atom bombardment tandem mass spectrometry; An unknown adipokinetic hormone (AKH-III) from Locusta migratoria

    Energy Technology Data Exchange (ETDEWEB)

    Heerma, W.; Versluis, C.; Lankhof, H. (Utrecht University (Netherlands). Faculty of Chemistry, Department of Analytical Molecular Spectrometry); Oudejans, R.C.H.M.; Kooiman, F.P.; Beenakkers, A.M.T. (Utrecht University (Netherlands). Department of Experimental Zoology)

    1991-08-01

    Fast atom bombardment mass spectrometry combined with various tandem mass spectrometric techniques and accurate mass measurement were used to elucidate the structure of an unknown biologically active peptide isolated from Locusa migratoria. (author). 23 refs.; 6 figs.; 2 schemes.

  20. Evaluation difference between mass of received cargo and mass of handed over the cargo in the determination of the masses by draft survey

    Directory of Open Access Journals (Sweden)

    Yakuta I. V.

    2016-12-01

    Full Text Available The paper provides the analysis of problems associated with the evaluation of difference between the mass of received and handed over cargo in determining the masses by draft survey and due to the difference in the measurement conditions at the loading and unloading ports (due to the change errors in various stages of the measurement procedures. The errors that may arise in determining the mass of the cargo due to roughness when measuring draft, due to using the inclinometer to determine the draft from one of boards, due to instrumental errors in the determination of the density of seawater, due to other possible errors have been investigated and evaluated. To estimate the errors of draft due to heaving and errors of inclinometer some formula are to be applied, their derivation has been done in this paper. It has been recommended to use the traditional formula of high-speed drawdown with the replacement of vessel speed on current rate to calculate the error of precipitation arising from the drawdowns ship on a current. The value per unit displacement draft from loading scale has been used to evaluate the error of the displacement appearing in the presence of draft errors. As a result two similar criteria (rigorous and statistical of allowable discrepancies calculated by draft survey mass of cargo in the port of loading and port of discharge have been substantiated. These criteria require the calculation and accumulation in a table of all the errors and calculate the total error of displacement. Criteria will allow the consignee and the carrier come to a reasonable and agreed decision about the significance of differences of the masses taking into account the indifference of conditions and measuring instruments.

  1. [Identification and quantitative determination of baclofen in human blood by HPLC with mass spectrometry detection].

    Science.gov (United States)

    Dukova, O A; Kotlovsky, M Yu; Pokrovsky, A A; Suvorova, E V; Shivrina, T G; Krasnov, E A; Efremov, A A

    2016-03-01

    A method of identification and quantitative determination of baclofen in blood by HPLC with mass spectrometry detection has been developed. It is characterized by high sensitivity, specificity, linearity, accuracy, reproducibility, and a low detection for quantitative determination. The method has been used for diagnostics of acute baclofen poisoning in patients.

  2. New evolutionary sequences for extremely low mass white dwarfs: Homogeneous mass and age determinations, and asteroseismic prospects

    CERN Document Server

    Althaus, Leandro G; Córsico, Alejandro H

    2013-01-01

    We provide a fine and homogeneous grid of evolutionary sequences for He-core white dwarfs with masses 0.15-0.45 Msun, including the mass range for ELM white dwarfs (<0.20Msun). The grid is appropriate for mass and age determination, and to study their pulsational properties. White dwarf sequences have been computed by performing full evolutionary calculations that consider the main energy sources and processes of chemical abundance changes during white dwarf evolution. Initial models for the evolving white dwarfs have been obtained by computing the non-conservative evolution of a binary system consisting of a Msun ZAMS star and a 1.4 Msun neutron star for various initial orbital periods. To derive cooling ages and masses for He-core white dwarf we perform a least square fitting of the M(Teff, g) and Age(Teff, g) relations provided by our sequences by using a scheme that takes into account the time spent by models in different regions of the Teff-g plane. This is useful when multiple solutions for cooling a...

  3. Accurate determination of accretion and photospheric parameters in Young Stellar Objects: the case of two candidate old disks in the Orion Nebula Cluster

    CERN Document Server

    Manara, C F; Da Rio, N; De Marchi, G; Natta, A; Ricci, L; Robberto, M; Testi, L

    2013-01-01

    Current planet formation models are largely based on the observational constraint that protoplanetary disks have lifetime 3Myr. Recent studies, however, report the existence of PMS stars with signatures of accretion (strictly connected with the presence of circumstellar disks)and photometrically determined ages of 30 Myr, or more. Here we present a spectroscopic study of two major age outliers in the ONC. We use broad band, intermediate resolution VLT/X-Shooter spectra combined with an accurate method to determine the stellar parameters and the related age of the targets to confirm their peculiar age estimates and the presence of ongoing accretion.The analysis is based on a multi-component fitting technique, which derives simultaneously SpT, extinction, and accretion properties of the objects. With this method we confirm and quantify the ongoing accretion. From the photospheric parameters of the stars we derive their position on the HRD, and the age given by evolutionary models. Together with other age indica...

  4. Determination of Isoflavone Content in SRM 3238 Using Liquid Chromatography-Particle Beam/Electron Ionization Mass Spectrometry

    Science.gov (United States)

    Zhang, Lynn X.; Burdette, Carolyn Q.; Phillips, Melissa M.; Rimmer, Catherine A.; Marcus, R. Kenneth

    2016-01-01

    The characterization of marker components in botanical materials is a challenging task and the increased consumption of botanicals and dietary supplements demands a greater understanding of the associated health benefits and risks. In order to successfully acquire and compare clinical results and correlate health trends, accurate, precise, and validated methods of analysis must be developed. Presented here is the development of a quantitative method for the determination of soy isoflavones (daidzin, glycitin, genistin, daidzein, and genistein) using liquid chromatography-particle beam/electron ionization mass spectrometry (LC-PB/EIMS). An internal standard (IS) approach for quantitation using 7-hydroxy-4-chromone as the IS compound was employed, with response factors for each individual isoflavone obtained from calibrant solutions. The results from this method were compared with the certified and reference values for NIST SRM 3238 Soy-Containing Solid Oral Dosage Form to demonstrate that the method was in control. Results obtained using LC-PB/EIMS were consistent with the NIST certified or reference values and their uncertainties for all five isoflavones, demonstrating that the LC-PB/EIMS approach is both accurate and precise when used for the determination of the target isoflavones in soy-containing dietary supplement finished products, while simultaneously providing structural information. PMID:26651559

  5. Accurate and self-consistent procedure for determining pH in seawater desalination brines and its manifestation in reverse osmosis modeling.

    Science.gov (United States)

    Nir, Oded; Marvin, Esra; Lahav, Ori

    2014-11-01

    Measuring and modeling pH in concentrated aqueous solutions in an accurate and consistent manner is of paramount importance to many R&D and industrial applications, including RO desalination. Nevertheless, unified definitions and standard procedures have yet to be developed for solutions with ionic strength higher than ∼0.7 M, while implementation of conventional pH determination approaches may lead to significant errors. In this work a systematic yet simple methodology for measuring pH in concentrated solutions (dominated by Na(+)/Cl(-)) was developed and evaluated, with the aim of achieving consistency with the Pitzer ion-interaction approach. Results indicate that the addition of 0.75 M of NaCl to NIST buffers, followed by assigning a new standard pH (calculated based on the Pitzer approach), enabled reducing measured errors to below 0.03 pH units in seawater RO brines (ionic strength up to 2 M). To facilitate its use, the method was developed to be both conceptually and practically analogous to the conventional pH measurement procedure. The method was used to measure the pH of seawater RO retentates obtained at varying recovery ratios. The results matched better the pH values predicted by an accurate RO transport model. Calibrating the model by the measured pH values enabled better boron transport prediction. A Donnan-induced phenomenon, affecting pH in both retentate and permeate streams, was identified and quantified.

  6. Evaluation of the occurrence and biodegradation of parabens and halogenated by-products in wastewater by accurate-mass liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-QTOF-MS).

    Science.gov (United States)

    González-Mariño, Iria; Quintana, José Benito; Rodríguez, Isaac; Cela, Rafael

    2011-12-15

    An assessment of the sewage occurrence and biodegradability of seven parabens and three halogenated derivatives of methyl paraben (MeP) is presented. Several wastewater samples were collected at three different wastewater treatment plants (WWTPs) during April and May 2010, concentrated by solid-phase extraction (SPE) and analysed by liquid chromatography-electrospray-quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS). The performance of the QTOF system proved to be comparable to triple-quadrupole instruments in terms of quantitative capabilities, with good linearity (R(2) > 0.99 in the 5-500 ng mL(-1) range), repeatability (RSD paraben (n-PrP) were the most frequently detected and the most abundant analytes in raw wastewater (0.3-10 μg L(-1)), in accordance with the data displayed in the bibliography and reflecting their wider use in cosmetic formulations. Samples were also evaluated in search for potential halogenated by-products of parabens, formed as a result of their reaction with residual chlorine contained in tap water. Monochloro- and dichloro-methyl paraben (ClMeP and Cl(2)MeP) were found and quantified in raw wastewater at levels between 0.01 and 0.1 μg L(-1). Halogenated derivatives of n-PrP could not be quantified due to the lack of standards; nevertheless, the monochlorinated species (ClPrP) was identified in several samples from its accurate precursor and product ions mass/charge ratios (m/z). Removal efficiencies of parabens and MeP chlorinated by-products in WWTPs exceeded 90%, with the lowest percentages corresponding to the latter species. This trend was confirmed by an activated sludge biodegradation batch test, where non-halogenated parabens had half-lives lower than 4 days, whereas halogenated derivatives of MeP turned out to be more persistent, with up to 10 days of half-life in the case of dihalogenated derivatives. A further stability test performed with raw wastewater also showed that parabens degrade rapidly in real sewage, with

  7. Correction factor for real-time determination of wood dust mass concentration by photometric method

    Directory of Open Access Journals (Sweden)

    Ankica Čavlović

    2009-03-01

    Full Text Available Samples of wood dust were collected in the working environment of wood machining processes for the purpose of determining correction factors for measuring mass concentration of wood dust by photometric method. According to the NIOSH 0600 Norm and NIOSH Manual of Analytical Methods for photometric measurement, correction factor must be determined before measuring mass concentration of different types of dust. The correction factor is defined as the ratio of mass concentration obtained by the gravimetric method and mass concentration obtained by the photometric method. The correction factor should be determined because of the influence of particle size distribution, density, particle shape and refractive index on values obtained by the photometric method. The aim of the research was to investigate the possibility of using photometric method for the determination of mass concentration of inhalable fraction of airborne wood dust. Sampling was conducted in several woodworking plants during the machining of wet and dry beech-wood, wet and dry oak-wood, wet fir-wood and particleboard. There is a significant correlation between the results obtained by the photometric method and values obtained by the gravimetric method (R2=0.88 and this is the base for using the photometric method in determining mass concentration of airborne wood dust. According to the results of this research, correction factors must be determined and used for measuring mass concentration of inhalable wood dust during the machining of different wood species and wood with different moisture content. The best corresponding results of photometric and gravimetric methods are obtained for the samples collected during machining of wet fir-wood (k=1. The largest correction factor should be used in determining workers exposure to wood dust during machining of dry oak-wood (k=4.4 and particleboard (k=4.5. Only the results of 8-hour measurements of mass concentration by gravimetric methods can

  8. A method for determination mass absorption coefficient of gamma rays by Compton scattering.

    Science.gov (United States)

    El Abd, A

    2014-12-01

    A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed.

  9. Determination of alkylphenol and alkylphenolethoxylates in biota by liquid chromatography with detection by tandem mass spectrometry and fluorescence spectroscopy

    Science.gov (United States)

    Schmitz-Afonso, I.; Loyo-Rosales, J.E.; de la Paz Aviles, M.; Rattner, B.A.; Rice, C.P.

    2003-01-01

    A quantitative method for the simultaneous determination of octylphenol, nonylphenol and the corresponding ethoxylates (1 to 5) in biota is presented. Extraction methods were developed for egg and fish matrices based on accelerated solvent extraction followed by a solid-phase extraction cleanup, using octadecylsilica or aminopropyl cartridges. Identification and quantitation were accomplished by liquid chromatography-electrospray tandem mass spectrometry (LC-MS-MS) and compared to the traditional liquid chromatography with fluorescence spectroscopy detection. LC-MS-MS provides high sensitivity and specificity required for these complex matrices and an accurate quantitation with the use of 13C-labeled internal standards. Quantitation limits by LC-MS-MS ranged from 4 to 12 ng/g in eggs, and from 6 to 22 ng/g in fish samples. These methods were successfully applied to osprey eggs from the Chesapeake Bay and fish from the Great Lakes area. Total levels found in osprey egg samples were up to 18 ng/g wet mass and as high as 8.2 ug/g wet mass in the fish samples.

  10. Purge and trap method to determine alpha factors of VOC liquid-phase mass transfer coefficients

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A theoretical approach and laboratory practice of determining the alpha factors of volatile organic compound (VOC) liquid-phase mass transfer coefficients are present in this study.Using Purge Trap Concentrator, VOC spiked water samples are purged by high-purity nitrogen in the laboratory, the VOC liquid-phase mass transfer rate constants under the laboratory conditions are then obtained by observing the variation of VOCs purged out of the water with the purge time.The alpha factors of VOC liquid-phase mass transfer coefficients are calculated as the ratios of the liquid-phase mass transfer rate constants in real water samples to their counterparts in pure water under the same experimental conditions. This direct and fast approach is easy to control in the laboratory, and would benefit mutual comparison among researchers, so might be useful for thestudy of VOC mass transfer across the liquid-gas interface.

  11. New method for precise determination of top quark mass at LHC

    CERN Document Server

    Kawabata, Sayaka

    2015-01-01

    Current measurements of the top quark mass which have achieved a precision of less than 1 GeV involve a theoretical problem that the definition of the measured mass is ambiguous in perturbation theory. As a possible solution to the problem, we present a new method to measure the top quark mass at the LHC. This method uses lepton energy distribution and has a boost-invariant nature. We discuss strategies towards a precise determination of theoretically well-defined top quark masses such as the MSbar mass with the method. As a first step in this direction, a simulation analysis at the leading order is performed considering actual experimental circumstances. The result indicates that this method with further improvements is capable of realizing a precision of less than 1 GeV at the LHC.

  12. Determination and correlation of mass transfer coefficients in a stirred cell. [Molten Salt Breeder Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Herranz, J.; Bloxom, S.R.; Keeler, J.B.; Roth, S.R.

    1975-12-17

    In the proposed Molten Salt Breeder Reactor flowsheet, a fraction of the rare earth fission products is removed from the fuel salt in mass transfer cells. To obtain design parameters for this extraction, the effect of cell size, blade diameter, phase volume, and agitation rate on the mass transfer for a high density ratio system (mercury/water) in nondispersing square cross section contactors was determined. Aqueous side mass transfer coefficients were measured by polarography over a wide range of operating conditions. Correlations for the experimental mass transfer coefficients as functions of the operating parameters are presented. Several techniques for measuring mercury-side mass transfer coefficients were evaluated and a new one is recommended. (auth)

  13. Improved microwave-assisted wet digestion procedures for accurate Se determination in fish and shellfish by flow injection-hydride generation-atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lavilla, I. [Departamento de Quimica Analitica y Alimentaria, Area de Quimica Analitica, Universidad de Vigo, Facultad de Ciencias (Quimica), As Lagoas - Marcosende s/n, 36310 Vigo (Spain); Gonzalez-Costas, J.M. [Departamento de Quimica Analitica y Alimentaria, Area de Quimica Analitica, Universidad de Vigo, Facultad de Ciencias (Quimica), As Lagoas - Marcosende s/n, 36310 Vigo (Spain); Bendicho, C. [Departamento de Quimica Analitica y Alimentaria, Area de Quimica Analitica, Universidad de Vigo, Facultad de Ciencias (Quimica), As Lagoas - Marcosende s/n, 36310 Vigo (Spain)]. E-mail: bendicho@uvigo.es

    2007-05-22

    Accurate determination of Se in biological samples, especially fish and shellfish, by hydride generation techniques has generally proven troublesome owing to the presence of organoselenium that cannot readily converted into inorganic selenium under usual oxidising conditions. Further improvements in the oxidation procedures are needed so as to obtain accurate concentration values when this type of samples is analyzed. Microwave-assisted wet digestion (MAWD) procedures of seafood based on HNO{sub 3} or the mixture HNO{sub 3}/H{sub 2}O{sub 2} and further thermal reduction of the Se(VI) formed to Se(IV) were evaluated. These procedures were as follows: (I) without H{sub 2}O{sub 2} and without heating to dryness; (II) without H{sub 2}O{sub 2} and with heating to dryness; (III) with H{sub 2}O{sub 2} and without heating to dryness; (IV) with H{sub 2}O{sub 2} and with heating to dryness. In general, low recoveries of selenium are obtained for several marine species (e.g., crustaceans and cephalopods), which may be ascribed to the presence of Se forms mainly associated with nonpolar proteins and lipids. Post-digestion UV irradiation proved very efficient since not only complete organoselenium decomposition was achieved but also the final step required for prereduction of Se(VI) into Se(IV) (i.e. heating at 90 deg. C for 30 min in 6 M HCl) could be avoided. With the MAWD/UV procedure, the use of strong oxidising agents (persuphate, etc.) or acids (e.g. perchloric acid) which are typically applied prior to Se determination by hydride generation techniques is overcome, and as a result, sample pre-treatment is significantly simplified. The method was successfully validated against CRM DOLT-2 (dogfish liver), CRM DORM-2 (dogfish muscle) and CRM TORT-2 (lobster hepatopancreas). Automated ultrasonic slurry sampling with electrothermal atomic absorption spectrometry was also applied for comparison. Total Se contents in ten seafood samples were established. Se levels ranged from 0

  14. DETERMINATION OF ACRYLAMIDE IN FOOD BY GAS AND LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

    OpenAIRE

    Michaela Vieriková; Miriam Vlčáková

    2010-01-01

     Acrylamide in food was determined by gas chromatography - mass spectrometry (GC-MS) after bromination of acrylamide and underivatized acrylamide was quantified by ultra performance liquid chromatography -mass spectrometry (UPLC-MS). Two different sample preparation methods were used and optimised. The GC-MS method was used for various food matrices like breads, potato crisps, potato crackers, french fries. The UPLC-MS method was used for analysis of coffee. The limit of detect...

  15. Determination of ricin by nano liquid chromatography/mass spectrometry after extraction using lactose-immobilized monolithic silica spin column.

    Science.gov (United States)

    Kanamori-Kataoka, Mieko; Kato, Haruhito; Uzawa, Hirotaka; Ohta, Shigenori; Takei, Yoshiyuki; Furuno, Masahiro; Seto, Yasuo

    2011-08-01

    Ricin is a glycosylated proteinous toxin that is registered as toxic substance by Chemical Weapons convention. Current detection methods can result in false negatives and/or positives, and their criteria are not based on the identification of the protein amino acid sequences. In this study, lactose-immobilized monolithic silica extraction followed by tryptic digestion and liquid chromatography/mass spectrometry (LC/MS) was developed as a method for rapid and accurate determination of ricin. Lactose, which was immobilized on monolithic silica, was used as a capture ligand for ricin extraction from the sample solution, and the silica was supported in a disk-packed spin column. Recovery of ricin was more than 40%. After extraction, the extract was digested with trypsin and analyzed by LC/MS. The accurate masses of molecular ions and MS/MS spectra of the separated peptide peaks were measured by Fourier transform-MS and linear iontrap-MS, respectively. Six peptides, which were derived from the ricin A-(m/z 537.8, 448.8 and 586.8) and B-chains (m/z 701.3, 647.8 and 616.8), were chosen as marker peptides for the identification of ricin. Among these marker peptides, two peptides were ricin-specific. This method was applied to the determination of ricin from crude samples. The monolithic silica extraction removed most contaminant peaks from the total ion chromatogram of the sample, and the six marker peptides were clearly detected by LC/MS. It takes about 5 h for detection and identification of more than 8 ng/ml of ricin through the whole handling, and this procedure will be able to deal with the terrorism using chemical weapon.

  16. Differential Label-free Quantitative Proteomic Analysis of Shewanella oneidensis Cultured under Aerobic and Suboxic Conditions by Accurate Mass and Time Tag Approach

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Ruihua; Elias, Dwayne A.; Monroe, Matthew E.; Shen, Yufeng; McIntosh, Martin; Wang, Pei; Goddard, Carrie D.; Callister, Stephen J.; Moore, Ronald J.; Gorby, Yuri A.; Adkins, Joshua N.; Fredrickson, Jim K.; Lipton, Mary S.; Smith, Richard D.

    2006-04-01

    We describe the application of liquid chromatography coupled to mass spectrometry (LC/MS) without the use of stable isotope labeling for differential quantitative proteomics analysis of whole cell lysates of Shewanella oneidensis MR-1 cultured under aerobic and sub-oxic conditions. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to initially identify peptide sequences, and LC coupled to Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR) was used to confirm these identifications, as well as measure relative peptide abundances. 2343 peptides, covering 668 proteins were identified with high confidence and quantified. Among these proteins, a subset of 56 changed significantly using statistical approaches such as SAM, while another subset of 56 that were annotated as performing housekeeping functions remained essentially unchanged in relative abundance. Numerous proteins involved in anaerobic energy metabolism exhibited up to a 10-fold increase in relative abundance when S. oneidensis is transitioned from aerobic to sub-oxic conditions.

  17. Study of Key Factors Determinant Choice of Rail-Based Mass Transit

    Directory of Open Access Journals (Sweden)

    Ircham

    2016-07-01

    Full Text Available Pursuant to regulations of the Ministry of Transportation in 2002 about the type of transport based on the city size, the metropolis with a population of more than 1 million inhabitants are required to have the urban mass transit. Nevertheless, until now not all city-scale population of more than 1 million have mass public transport, either bus or rail-based. Especially for rail-based mass transit, indicated the existing regulations have not been able to challenge the development of rail-based urban mass transit. Learning from the literature study and the experience of countries that already have rail-based urban mass transit it has acquired nine main factors to be taken into account in developing a rail-based urban public transportation. This study was conducted by using Analytical Hierarchy Process method which was further validated through the implementation of the On Focus Group Discussion in the Jakarta City Transportation Council (DTKJ as well as in the City Development Planning Board (Bappeko Surabaya. Finally, the initial result shown five sequences determining factor for the determinant choice of rail-based mass transit, namely: fiscal or economic capacity of the region and society, transport policy, integrated public transport, land use, fare and travel time. Furthermore, the acquisition results of this study can be applied to the selected cities to address the challenges to urban mass transit development.

  18. [Simultaneous determination of 16 organic acids in feed additives by on-line enrichment and ion chromatography-mass spectrometry].

    Science.gov (United States)

    Xiong, Zhiyu; Dong, Ying; Zhou, Hongbin; Yu, Yang; Li, Jing; Sun, Li

    2014-02-01

    A novel analytical method for simultaneous determination of sixteen organic acids by on-line enrichment and ion chromatography-mass spectrometry (IC-MS) was developed. Online enrichment and separation of the organic acids were performed by ion chromatography on a homemade enrichment column and a homemade separation column. The qualitative and quantitative analyses of the organic acids were performed by mass spectrometry in selected ion monitoring (SIM) mode on the basis of atmospheric pressure chemical ionization (APCI) source in negative mode. The sample of 200 microL was injected for the analysis, and the on-line enrichment time was 3 min. The sodium hydroxide solution was used as a gradient elution system. The two columns made it possible to have a low limit of detection due to the good enrichment and separation capability. The sixteen organic acids were separated completely within 30 min. All curves showed good linearity within the test concentration ranges. The limits of detection (LODs) were between 0.01 and 0.22 mg/L, and the average recoveries were between 70.6% and 110.8%. The relative standard deviations (RSDs) were less than 6.3%. The results indicate that this method is simple, rapid, sensitive and accurate for the determination of the organic acids in feed additives.

  19. Strong IR Cancellation in Heavy Quarkonium and Precise Top Mass Determination

    CERN Document Server

    Kiyo, Y; Sumino, Y

    2015-01-01

    Combining recent perturbative analyses on the static QCD potential and the quark pole mass, we find that, for the heavy quarkonium states $c\\bar{c}$, $b\\bar{b}$ and $t\\bar{t}$, (1) ultra-soft (US) corrections in the binding energies are small, and (2) there is a stronger cancellation of IR contributions than what has been predicted by renormalon dominance hypothesis. By contrast, for a hypothetical heavy quarkonium system with a small number of active quark flavors ($n_l\\approx 0$), we observe evidence that renormalon dominance holds accurately and that non-negligible contributions from US corrections exist. As an important consequence, we improve on a previous prediction for possible achievable accuracy of top quark $\\overline{\\rm MS}$--mass measurement at a future linear collider and estimate that in principle about 20 MeV accuracy is reachable.

  20. Determination of Mass Transfer Parameters During Deep Fat Frying of Rice Crackers

    Institute of Scientific and Technical Information of China (English)

    Mohammad Taghi Hamed MOSAVIAN; Vahid Mohammadpour KARIZAKI

    2012-01-01

    The accuracy of the knowledge of mass transfer parameters (effective moisture diffusivity,mass transfer Biot number and mass transfer coefficient) in the case of frying food,is essential and important for designing,modeling and process optimization.This study is undertaken to develop an approach for determining mass transfer parameters during frying of spherical rice cracker in sunflower oil at 150,170 and 190 ℃.These parameters were evaluated from the plots of dimensionless concentration ratios against time of frying.Effective moisture diffusivity,mass transfer Biot number and mass transfer coefficient ranged between 1.24×10-8 to 2.36×10-8 m2/s,1.96 to 2.34 and 5.51×10-6 to 9.70×10-6 m/s,respectively.Effective moisture diffusivity and mass transfer coefficient were found to increase with an increasing frying temperature,whereas mass transfer Biot number decreased.An Arrhenius-type relationship was found between effective diffusivity coefficient and frying temperature.

  1. A rapid and accurate method for determining protein content in dairy products based on asynchronous-injection alternating merging zone flow-injection spectrophotometry.

    Science.gov (United States)

    Liang, Qin-Qin; Li, Yong-Sheng

    2013-12-01

    An accurate and rapid method and a system to determine protein content using asynchronous-injection alternating merging zone flow-injection spectrophotometry based on reaction between coomassie brilliant blue G250 (CBBG) and protein was established. Main merit of our approach is that it can avoid interferences of other nitric-compounds in samples, such as melamine and urea. Optimized conditions are as follows: Concentrations of CBBG, polyvinyl alcohol (PVA), NaCl and HCl are 150 mg/l, 30 mg/l, 0.1 mol/l and 1.0% (v/v), respectively; volumes of the sample and reagent are 150 μl and 30 μl, respectively; length of a reaction coil is 200 cm; total flow rate is 2.65 ml/min. The linear range of the method is 0.5-15 mg/l (BSA), its detection limit is 0.05 mg/l, relative standard deviation is less than 1.87% (n=11), and analytical speed is 60 samples per hour.

  2. A Comprehensive Review of School-Based Body Mass Index Screening Programs and Their Implications for School Health: Do the Controversies Accurately Reflect the Research?

    Science.gov (United States)

    Ruggieri, Dominique G.; Bass, Sarah B.

    2015-01-01

    Background: Whereas legislation for body mass index (BMI) surveillance and screening programs has passed in 25 states, the programs are often subject to ethical debates about confidentiality and privacy, school-to-parent communication, and safety and self-esteem issues for students. Despite this debate, no comprehensive analysis has been completed…

  3. Direct molecular mass determination of trehalose monomycolate from 11 species of mycobacteria by MALDI-TOF mass spectrometry.

    Science.gov (United States)

    Fujita, Yukiko; Naka, Takashi; Doi, Takeshi; Yano, Ikuya

    2005-05-01

    Direct estimation of the molecular mass of single molecular species of trehalose 6-monomycolate (TMM), a ubiquitous cell-wall component of mycobacteria, was performed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. When less than 1 microg TMM was analysed by MALDI-TOF mass spectrometry, quasimolecular ions [M+Na]+ of each molecular species were demonstrated and the numbers of carbons and double bonds (or cyclopropane rings) were determined. Since the introduction of oxygen atoms such as carbonyl, methoxy and ester groups yielded the appropriate shift of mass ions, the major subclasses of mycolic acid (alpha, methoxy, keto and wax ester) were identified without resorting to hydrolytic procedures. The results showed a marked difference in the molecular species composition of TMM among mycobacterial species. Unexpectedly, differing from other mycoloyl glycolipids, TMM from Mycobacterium tuberculosis showed a distinctive mass pattern, with abundant odd-carbon-numbered monocyclopropanoic (or monoenoic) alpha-mycolates besides dicyclopropanoic mycolate, ranging from C75 to C85, odd- and even-carbon-numbered methoxymycolates ranging from C83 to C94 and even- and odd-carbon-numbered ketomycolates ranging from C83 to C90. In contrast, TMM from Mycobacterium bovis (wild strain and BCG substrains) possessed even-carbon-numbered dicyclopropanoic alpha-mycolates. BCG Connaught strain lacked methoxymycolates almost completely. These results were confirmed by MALDI-TOF mass analysis of mycolic acid methyl esters liberated by alkaline hydrolysis and methylation of the original TMM. Wax ester-mycoloyl TMM molecular species were demonstrated for the first time as an intact form in the Mycobacterium avium-intracellulare group, M. phlei and M. flavescens. The M. avium-intracellulare group possessed predominantly C85 and C87 wax ester-mycoloyl TMM, while M. phlei and the rapid growers tested contained C80, C81, C82 and C83 wax ester

  4. Quantification and isotope ratio determination of uranium in particles of environmental samples using isotope dilution thermal ionization mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Choi, Eun-Ju [Chungnam National University, Daejeon (Korea, Republic of)

    2015-10-15

    Highly accurate and precise quantitative and qualitative analysis of nuclear materials in environmental samples plays essential roles in monitoring undeclared nuclear activities of corresponding facilities. The former focuses on the quantification of uranium (U) and plutonium (Pu) contained in a whole sample, while the latter enables us to acquire the isotopic ratios, which serve as the crucial basis to trace the nuclear histories of a facility. However, the quantity of nuclear materials in a single-particle has not been acquired from the particle analysis, but has been estimated by the size of the particles. This report is to describe the method developed to determine the quantity and the isotopic ratios of uranium in a micro-particle simultaneously. Complete dissolution of particle-spike mixture by repeated addition of nitric acid on a rhenium filament was performed to ensure the homogeneity of the mixture. Thermal ionization mass spectrometry (TIMS) was utilized to measure the U isotope ratios of the mixture with high accuracy. The isotopic ratios of the uranium in the particle sample were determined by mathematical deconvolution of U isotopic ratios of the mixture. Verification using particles of a certified reference material showed that the newly developed method can be used to quantify and to determine the isotopic ratios of U in a particle simultaneously. The development of a method for simultaneous determination of the quantity and the isotope ratios of uranium contained in particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS) was described. For homogeneity of the mixture of particles and spike, repeated dissolution using nitric acid for five times was performed.

  5. Determination of steel bar dispersed mass in electric discharge with alternative electrode

    Science.gov (United States)

    Shakirova, G. Yu; Shakirov, Yu I.; Ilyin, V. I.; Valiev, R. A.; Drogaylova, L. N.

    2017-01-01

    The mathematical model of plane problem of metal bar dispersion in electric discharge with liquid electrolyte is suggested in this research. The analogy with the plane problem of the theory of jets in an ideal fluid is used to solve the task. It actually means determination of analytic function in the field with one area of unknown boundary. The formula for determination of dispersed metal powder mass assuming the bar axial symmetry has been calculated.

  6. Determination of the LEP centre-of-mass energy from Z$\\gamma$ events

    CERN Document Server

    Barate, R; Ghez, P; Goy, C; Jézéquel, S; Lees, J P; Martin, F; Merle, E; Minard, M N; Pietrzyk, B; Przysiezniak, H; Alemany, R; Casado, M P; Chmeissani, M; Crespo, J M; Fernández, E; Fernández-Bosman, M; Garrido, L; Graugès-Pous, E; Juste, A; Martínez, M; Merino, G; Miquel, R; Mir, L M; Morawitz, P; Pacheco, A; Park, I C; Riu, I; Colaleo, A; Creanza, D; De Palma, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Becker, U; Boix, G; Cattaneo, M; Cerutti, F; Ciulli, V; Dissertori, G; Drevermann, H; Forty, Roger W; Frank, M; Gianotti, F; Greening, T C; Halley, A W; Hansen, J B; Harvey, J; Janot, P; Jost, B; Lehraus, Ivan; Leroy, O; Loomis, C; Maley, P; Mato, P; Minten, Adolf G; Moutoussi, A; Ranjard, F; Rolandi, Luigi; Schlatter, W D; Schmitt, M; Schneider, O; Spagnolo, P; Tejessy, W; Teubert, F; Tomalin, I R; Tournefier, E; Wright, A E; Ajaltouni, Ziad J; Badaud, F; Chazelle, G; Deschamps, O; Dessagne, S; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Vayaki, Anna; Blondel, A; Brient, J C; Machefert, F P; Rougé, A; Swynghedauw, M; Tanaka, R; Valassi, Andrea; Videau, H L; Focardi, E; Parrini, G; Zachariadou, K; Cavanaugh, R J; Corden, M; Georgiopoulos, C H; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Chalmers, M; Curtis, L; Lynch, J G; Negus, P; O'Shea, V; Räven, B; Raine, C; Smith, D; Teixeira-Dias, P; Thompson, A S; Ward, J J; Buchmüller, O L; Dhamotharan, S; Geweniger, C; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Marinelli, N; Martin, E B; Nash, J; Nowell, J; Sciabà, A; Sedgbeer, J K; Thomson, E; Williams, M D; Ghete, V M; Girtler, P; Kneringer, E; Kuhn, D; Rudolph, G; Bowdery, C K; Buck, P G; Ellis, G; Finch, A J; Foster, F; Hughes, G; Jones, R W L; Robertson, N A; Smizanska, M; Williams, M I; Giehl, I; Hölldorfer, F; Jakobs, K; Kleinknecht, K; Kröcker, M; Müller, A S; Nürnberger, H A; Quast, G; Renk, B; Rohne, E; Sander, H G; Schmeling, S; Wachsmuth, H W; Zeitnitz, C; Ziegler, T; Aubert, Jean-Jacques; Benchouk, C; Bonissent, A; Carr, J; Coyle, P; Ealet, A; Fouchez, D; Motsch, F; Payre, P; Rousseau, D; Talby, M; Thulasidas, M; Tilquin, A; Aleppo, M; Antonelli, M; Gilardoni, S S; Ragusa, F; Büscher, V; Dietl, H; Ganis, G; Hüttmann, K; Lütjens, G; Mannert, C; Männer, W; Moser, H G; Schael, S; Settles, Ronald; Seywerd, H C J; Stenzel, H; Wiedenmann, W; Wolf, G; Azzurri, P; Boucrot, J; Callot, O; Chen, S; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacholkowska, A; Kado, M; Lefrançois, J; Serin, L; Veillet, J J; Videau, I; De Vivie de Régie, J B; Zerwas, D; Bagliesi, G; Bettarini, S; Boccali, T; Bozzi, C; Calderini, G; Dell'Orso, R; Ferrante, I; Giassi, A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Rizzo, G; Sanguinetti, G; Sguazzoni, G; Tenchini, Roberto; Vannini, C; Venturi, A; Verdini, P G; Blair, G A; Coles, J; Cowan, G D; Green, M G; Hutchcroft, D E; Jones, L T; Medcalf, T; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Norton, P R; Thompson, J C; Bloch-Devaux, B; Colas, P; Fabbro, B; Faïf, G; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Rosowsky, A; Trabelsi, A; Tuchming, B; Vallage, B; Black, S N; Dann, J H; Kim, H Y; Konstantinidis, N P; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Cartwright, S L; Combley, F; Hodgson, P N; Kelly, M S; Lehto, M H; Thompson, L F; Affholderbach, K; Böhrer, A; Brandt, S; Grupen, Claus; Hess, J; Misiejuk, A; Prange, G; Sieler, U; Giannini, G; Gobbo, B; Pütz, J; Rothberg, J E; Wasserbaech, S R; Williams, R W; Armstrong, S R; Elmer, P; Ferguson, D P S; Gao, Y; González, S; Hayes, O J; Hu, H; Jin, S; McNamara, P A; Nielsen, J; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Wu Sau Lan; Wu, X; Zobernig, G

    1999-01-01

    Radiative returns to the Z resonance (Z\\gamma events) are used to determine the LEP2 centre-of-mass energy from the data collected with the ALEPH detector in 1997. The average centre-of-mass energy is measured to be: E_CM = 182.50 +- 0.19 (stat.) +- 0.08 (syst.) GeV in good agreement with the precise determination by the LEP energy working group of 182.652 +- 0.050 GeV. If applied to the measurement of the W mass, its precision translates into a systematic error on M_W which is smaller than the statistical error achieved from the corresponding dataset.

  7. Rapid determination of sucrose in chocolate mass using near infrared spectroscopy.

    Science.gov (United States)

    da Costa Filho, Paulo Augusto

    2009-01-12

    This paper reports the results of a rapid method to determine sucrose in chocolate mass using near infrared spectroscopy (NIRS). We applied a broad-based calibration approach, which consists in putting together in one single calibration samples of various types of chocolate mass. This approach increases the concentration range for one or more compositional parameters, improves the model performance and requires just one calibration model for several recipes. The data were modelled using partial least squares (PLS) and multiple linear regression (MLR). The MLR models were developed using a variable selection based on the coefficient regression of PLS and genetic algorithm (GA). High correlation coefficients (0.998, 0.997, 0.998 for PLS, MLR and GA-MLR, respectively) and low prediction errors confirms the good predictability of the models. The results show that NIR can be used as rapid method to determine sucrose in chocolate mass in chocolate factories.

  8. Determination of daminozide in apples and apple leaves by liquid chromatography-mass spectrometry

    NARCIS (Netherlands)

    Mol, H.G.J.; Dam, R.C.J. van; Vreeken, R.J.; Steijger, O.M.

    1999-01-01

    A straightforward and efficient method was developed for the determination of intact daminozide in apples and apple leaves. After extraction with methanol and a clean-up step using a graphitized carbon cartridge, the extract was analysed by ion-trap liquid chromatography-tandem mass spectrometry (LC

  9. Determinants of Left Ventricular Mass and Hypertrophy in Hemodialysis Patients Assessed by Cardiac Magnetic Resonance Imaging

    OpenAIRE

    Patel, Rajan K.; Oliver, Scott; Mark, Patrick B.; Powell, Joanna R.; Emily P. McQuarrie; Traynor, James P.; Dargie, Henry J.; Jardine, Alan G.

    2009-01-01

    Background and objectives: Left ventricular hypertrophy (LVH) is an independent risk factor for premature cardiovascular death in hemodialysis (HD) patients and one of the three forms of uremic cardiomyopathy. Cardiovascular magnetic resonance (CMR) is a volume-independent technique to assess cardiac structure. We used CMR to assess the determinants of left ventricular mass (LVM) and LVH in HD patients.

  10. How to Determine the Centre of Mass of Bodies from Image Modelling

    Science.gov (United States)

    Dias, Marco Adriano; Carvalho, Paulo Simeão; Rodrigues, Marcelo

    2016-01-01

    Image modelling is a recent technique in physics education that includes digital tools for image treatment and analysis, such as digital stroboscopic photography (DSP) and video analysis software. It is commonly used to analyse the motion of objects. In this work we show how to determine the position of the centre of mass (CM) of objects with…

  11. Determination of the gas-to-membrane mass transfer coefficient in a catalytic membrane reactor

    NARCIS (Netherlands)

    Veldsink, J.W.; Versteeg, G.F.; Swaaij, W.P.M. van

    1995-01-01

    A novel method to determine the external mass transfer coefficient in catalytic membrane reactors (Sloot et al., 1992a, b) was presented in this study. In a catalytically active membrane reactor, in which a very fast reaction occurs, the external transfer coefficient can conveniently be measured by

  12. Simultaneous determination of seven flavonoids in Epimedium by liquid chromatography-tandem mass spectrometry method

    Institute of Scientific and Technical Information of China (English)

    Cai Sheng Wu; Bao Lin Guo; Yu Xin Sheng; Jin Lan Zhang

    2008-01-01

    In this paper, a sensitive and specific liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) method has been developed and validated for the identification and determination of seven flavonoids, namely epimedin A, epimedin B, epimedin C, icariin, sagittatoside B, 2"-0-rhamnosyl icariside II, and baohuoside I in Epimedium from different sources.

  13. Determination of Rest Mass Energy of the Electron by a Compton Scattering Experiment

    Science.gov (United States)

    Prasannakumar, S.; Krishnaveni, S.; Umesh, T. K.

    2012-01-01

    We report here a simple Compton scattering experiment which may be carried out in graduate and undergraduate laboratories to determine the rest mass energy of the electron. In the present experiment, we have measured the energies of the Compton scattered gamma rays with a NaI(Tl) gamma ray spectrometer coupled to a 1 K multichannel analyzer at…

  14. Project 8: Determining neutrino mass from tritium beta decay using a frequency-based method

    Energy Technology Data Exchange (ETDEWEB)

    Doe, Peter J.; Kofron, Jared N.; MCBride, Lisa; Robertson, R. G. H.; Rosenberg, Leslie; Rybka, Gray; Doelman, S.; Rogers, Alan E.; Formaggio, Joseph; Furse, Daniel; Oblath, Noah S.; LaRoque, Benjamin; Leber, Michelle; Monreal, Ben; Bahr, Matthew; Asner, David M.; Jones, Anthony M.; Fernandes, Justin L.; VanDevender, Brent A.; Patterson, Ryan B.; Bradley, Rich; Thummler, Thomas

    2013-10-04

    A general description is given of Project 8, a new approach to measuring the neutrino mass scale via the beta decay of tritium. In Project 8, the energy of electrons emitted in beta decay is determined from the frequency of cyclotron radiation emitted as the electrons spiral in a uniform magnetic field

  15. Determination of Mass Sensitivity of Crystal Quartz Resonators at Students' Laboratory

    Science.gov (United States)

    Greczylo, Tomasz; Mazur, Piotr; Debowska, Ewa; Wieczorek, Piotr

    2010-01-01

    This paper presents an experiment in which students determine the mass sensitivity of three crystal quartz resonators, designed to be carried out in "Physics Laboratory II" at the Institute of Experimental Physics, University of Wroclaw. The authors discuss the process of setting up the experiment and the results of the measurements.…

  16. Determination of Mass Sensitivity of Crystal Quartz Resonators at Students' Laboratory

    Science.gov (United States)

    Greczylo, Tomasz; Mazur, Piotr; Debowska, Ewa; Wieczorek, Piotr

    2010-01-01

    This paper presents an experiment in which students determine the mass sensitivity of three crystal quartz resonators, designed to be carried out in "Physics Laboratory II" at the Institute of Experimental Physics, University of Wroclaw. The authors discuss the process of setting up the experiment and the results of the measurements. They clearly…

  17. Experimental conditions for determination of the neutrino mass hierarchy with reactor antineutrinos

    Science.gov (United States)

    Pac, Myoung Youl

    2016-01-01

    This article reports the optimized experimental requirements to determine neutrino mass hierarchy using electron antineutrinos (νbare) generated in a nuclear reactor. The features of the neutrino mass hierarchy can be extracted from the | Δ m312 | and | Δ m322 | oscillations by applying the Fourier sine and cosine transforms to the L / E spectrum. To determine the neutrino mass hierarchy above 90% probability, the requirements on the energy resolution as a function of the baseline are studied at sin2 ⁡ 2θ13 = 0.1. If the energy resolution of the neutrino detector is less than 0.04 /√{Eν} and the determination probability obtained from Bayes' theorem is above 90%, the detector needs to be located around 48-53 km from the reactor(s) to measure the energy spectrum of νbare. These results will be helpful for setting up an experiment to determine the neutrino mass hierarchy, which is an important problem in neutrino physics.

  18. Determination of platinum in human subcellular microsamples by inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Björn, Erik; Nygren, Yvonne; Nguyen, Tam T. T. N.

    2007-01-01

    A fast and robust method for the determination of platinum in human subcellular microsamples by inductively coupled plasma mass spectrometry was developed, characterized, and validated. Samples of isolated DNA and exosome fractions from human ovarian (2008) and melanoma (T289) cancer cell lines...

  19. Determination of organophosphorus acids by thermo-spray liquid chromatography-mass spectrometry

    NARCIS (Netherlands)

    Wils, E.R.J.; Hulst, A.G.

    1988-01-01

    The determination of thirteen organophosphorus acids, hydrolysis products of nerve agents and pesticides, by a combination of ion-pair liquid chromatography on a reversed-phase C18 column and thermospray mass spectrometry was investigated. Ammonium acetate and three tetraalkylammonium salts with dif

  20. Determination of ion mobility collision cross sections for unresolved isomeric mixtures using tandem mass spectrometry and chemometric deconvolution.

    Science.gov (United States)

    Harper, Brett; Neumann, Elizabeth K; Stow, Sarah M; May, Jody C; McLean, John A; Solouki, Touradj

    2016-10-01

    Ion mobility (IM) is an important analytical technique for determining ion collision cross section (CCS) values in the gas-phase and gaining insight into molecular structures and conformations. However, limited instrument resolving powers for IM may restrict adequate characterization of conformationally similar ions, such as structural isomers, and reduce the accuracy of IM-based CCS calculations. Recently, we introduced an automated technique for extracting "pure" IM and collision-induced dissociation (CID) mass spectra of IM overlapping species using chemometric deconvolution of post-IM/CID mass spectrometry (MS) data [J. Am. Soc. Mass Spectrom., 2014, 25, 1810-1819]. Here we extend those capabilities to demonstrate how extracted IM profiles can be used to calculate accurate CCS values of peptide isomer ions which are not fully resolved by IM. We show that CCS values obtained from deconvoluted IM spectra match with CCS values measured from the individually analyzed corresponding peptides on uniform field IM instrumentation. We introduce an approach that utilizes experimentally determined IM arrival time (AT) "shift factors" to compensate for ion acceleration variations during post-IM/CID and significantly improve the accuracy of the calculated CCS values. Also, we discuss details of this IM deconvolution approach and compare empirical CCS values from traveling wave (TW)IM-MS and drift tube (DT)IM-MS with theoretically calculated CCS values using the projected superposition approximation (PSA). For example, experimentally measured deconvoluted TWIM-MS mean CCS values for doubly-protonated RYGGFM, RMFGYG, MFRYGG, and FRMYGG peptide isomers were 288.8 Å(2), 295.1 Å(2), 296.8 Å(2), and 300.1 Å(2); all four of these CCS values were within 1.5% of independently measured DTIM-MS values.

  1. Structural features of lipoarabinomannan from Mycobacterium bovis BCG. Determination of molecular mass by laser desorption mass spectrometry.

    Science.gov (United States)

    Venisse, A; Berjeaud, J M; Chaurand, P; Gilleron, M; Puzo, G

    1993-06-15

    It was recently shown that mycobacterial lipoarabinomannan (LAM) can be classified into two types (Chatterjee, D., Lowell, K., Rivoire B., McNeil M. R., and Brennan, P. J. (1992) J. Biol. Chem. 267, 6234-6239) according to the presence or absence of mannosyl residues (Manp) located at the nonreducing end of the oligoarabinosyl side chains. These two types of LAM were found in a pathogenic Mycobacterium tuberculosis strain and in an avirulent M. tuberculosis strain, respectively, suggesting that LAM with Manp characterizes virulent and "disease-inducing strains." We now report the structure of the LAM from Mycobacterium bovis Bacille Calmette-Guérin (BCG) strain Pasteur, largely used throughout the world as vaccine against tuberculosis. Using an up-to-date analytical approach, we found that the LAM of M. bovis BCG belongs to the class of LAMs capped with Manp. By means of two-dimensional homonuclear and heteronuclear scalar coupling NMR analysis and methylation data, the sugar spin system assignments were partially established, revealing that the LAM contained two types of terminal Manp and 2-O-linked Manp. From the following four-step process: (i) partial hydrolysis of deacylated LAM (dLAM), (ii) oligosaccharide derivatization with aminobenzoic ethyl ester, (iii) HPLC purification, (iv) FAB/MS-MS analysis; it was shown that the dimannosyl unit alpha-D-Manp-(1-->2)-alpha-D-Manp is the major residue capping the termini of the arabinan of the LAM. In this report, LAM molecular mass determination was established using matrix-assisted UV-laser desorption/ionization mass spectrometry which reveals that the LAM molecular mass is around 17.4 kDa. The similarity of the LAM structures between M. bovis BCG and M. tuberculosis H37Rv is discussed in regard to their function in the immunopathology of mycobacterial infection.

  2. [Simultaneous determination of eleven sex hormones in antler velvet health products by gas chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Lu, Chunmei; Wang, Mingtai; Mu, Jun; Lu, Lijun; Zhou, Xiao

    2011-06-01

    A method for the simultaneous determination of 11 sex hormones in antler velvet health products by gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed. The sex hormones in antler velvet were enriched and purified by solid phase extraction and derivatized with heptafluorobutyric acid anhydride (HFBA). A DB-5 column (30 m x 0.25 mm, 0.25 microm) with nonlinear gradient program was used in GC separation. The sex hormones were determined in the multiple reaction monitoring mode. The method realized the complete separation of 11 sex hormones. The limits of detection of this method were from 1.0 to 5.0 microg/kg for the 11 sex hormones. The correlation coefficients were between 0.991 6 and 0.999 9. The recoveries were in the range of 67.4% - 99.1% with relative standard deviations (RSDs) of 2.6% - 13%. This method is accurate and reliable for the determination of the sex hormones in antler velvet health products.

  3. [Determination of 99 pesticide residues in Paeoniae Radix Alba by gas chromatography-triple quadrupole tandem mass spectrometry].

    Science.gov (United States)

    Liu, Xiaoqin; Tong, Ling; Meng, Wenting; Sun, Guoxiang

    2015-08-01

    A method was established for the simultaneous determination of 99 pesticide residues with combination of solid-phase extraction technique ( SPE) and gas chromatography-triple quadrupole tandem mass spectrometry (GC-QqQ-MS). The sample was extracted with ethyl acetate, and cleaned-up by an amino SPE column. The extract was determined by GC-MS/MS in multi-reaction monitoring (MRM) mode, and matrix-matched internal standard method was applied to quantify the pesticides. The results of all the 99 pesticides showed good linearity in the range of 0.001-0.25 mg/L, with correlation coefficients (r2) > 0.99. The limits of quantification (LOQs) were between 0.001-0.050 mg/kg. The recoveries were between 66.7% and 128.0% with RSD values typically lower than 18.3% at three spiked levels of 0.05, 0.10 and 0.20 mg/kg. This method has been applied to determine thirteen batches of commercially available samples, chlorpyriphos-ethyl and p,p'-DDE were detected in four batches of Paeoniae Radix Alba. The method is highly accurate, reliable and sensitive for monitoring the 99 pesticide residues in Paeoniae Radix Alba.

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

    Science.gov (United States)

    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.

  5. DETERMINATION OF CO2 MASSES IN THE EXHAUST GASES OF THE MARINE DIESEL ENGINES

    Directory of Open Access Journals (Sweden)

    Doru COSOFRET

    2016-05-01

    Full Text Available Currently, reducing CO2 emissions that contribute to the greenhouse effect is currently under attention of the relevant international bodies. In the field of maritime transport, in 2011 International Maritime Organization (IMO has taken steps to reduce emissions of CO2 from the exhaust gases of marine diesel engines on ships, by imposing their energy efficiency standards. In this regard, we conducted a laboratory study on a 4-stroke diesel engine naturally aspirated by using to power it diesel and different blends of biodiesel with diesel fuel. The purpose of the study was to determine the formulas for calculating the mass flow rates of CO2 from exhaust gases’ concentrations experimentally determined. Determining the mass flow of CO2 is necessary to calculate the energy efficiency coefficient of the ship to assess the energy efficiency of the board of the limits imposed by the IMO.

  6. Determination of mass density, dielectric, elastic, and piezoelectric constants of bulk GaN crystal.

    Science.gov (United States)

    Soluch, Waldemar; Brzozowski, Ernest; Lysakowska, Magdalena; Sadura, Jolanta

    2011-11-01

    Mass density, dielectric, elastic, and piezoelectric constants of bulk GaN crystal were determined. Mass density was obtained from the measured ratio of mass to volume of a cuboid. The dielectric constants were determined from the measured capacitances of an interdigital transducer (IDT) deposited on a Z-cut plate and from a parallel plate capacitor fabricated from this plate. The elastic and piezoelectric constants were determined by comparing the measured and calculated SAW velocities and electromechanical coupling coefficients on the Z- and X-cut plates. The following new constants were obtained: mass density p = 5986 kg/m(3); relative dielectric constants (at constant strain S) ε(S)(11)/ε(0) = 8.6 and ε(S)(11)/ε(0) = 10.5, where ε(0) is a dielectric constant of free space; elastic constants (at constant electric field E) C(E)(11) = 349.7, C(E)(12) = 128.1, C(E)(13) = 129.4, C(E)(33) = 430.3, and C(E)(44) = 96.5 GPa; and piezoelectric constants e(33) = 0.84, e(31) = -0.47, and e(15) = -0.41 C/m(2).

  7. 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).

    Science.gov (United States)

    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.

  8. The electron density of a-Oxalic acid dihydrate at 100 K by X-ray diffraction: a contribution to the IUCr Commission on Charge, Spin and Momentum Densities project on the accurate determination of electron densities

    NARCIS (Netherlands)

    Dam, J.; Harkema, S.; Feil, D.

    1983-01-01

    The results of the determination of the electron density of u-oxalic acid dihydrate at 100 K by means of X-ray diffraction are reported as part of the project on the accurate determination of electron densities which was initiated by the International Union of Crystallography. An extensive data set,

  9. Controlling quark mass determinations non-perturbatively in three-flavour QCD

    CERN Document Server

    Campos, Isabel; Pena, Carlos; Preti, David; Ramos, Alberto; Vladikas, Anastassios

    2016-01-01

    The determination of quark masses from lattice QCD simulations requires a non-perturbative renormalization procedure and subsequent scale evolution to high energies, where a conversion to the commonly used MS-bar scheme can be safely established. We present our results for the non-perturbative running of renormalized quark masses in Nf=3 QCD between the electroweak and a hadronic energy scale, where lattice simulations are at our disposal. Recent theoretical advances in combination with well-established techniques allows to follow the scale evolution to very high statistical accuracy, and full control of systematic effects.

  10. Coriolis Mass-Flowmeter for aerostatic gas amount determination in zero pressure stratosperic balloons.

    Science.gov (United States)

    Behar, Jean-Baptiste

    2016-07-01

    The CNES ballooning community regularly operates zero pressure balloons in many countries around the world (recently in France, Sweden, Canada and soon, Australia in 2017). An important operational flight parameter is the aerostatic gas mass injected into the balloon (currently helium and hydrogen in the study). Besides the lifting force, it determines mainly the ascent rate from which the adiabatic expansion depends directly. A too high ascent velocity in very cold air temperature profiles could result in a gas temperature drop which if too great, might induce brittleness of the envelope. A precise gas mass determination is therefore critical for performance as well as for mission safety. The various gas supply tanks in various countries all have different characteristics with possible uncertainties with regard to their volumes. This makes the currently used gas mass determination method based on supply tank pressure measurements unreliable. This method also relies on tank temperature, another source of inaccuracy in the gas amount determination. CNES has therefore prospected for alternative methods to reduce inaccuracies and perhaps also ease the operational procedures during balloon inflation. Coriolis mass-flowmeters which have reached industrial maturity, offer the great advantage over other flowmeters to be able to directly measure the mass of the transferred fluid, and not deducing it from other parameters as other types of flowmeters would do. An industrial contractor has been therefore assigned to integrate this solution into the CNES operational setup. This new system is to be tested in February 2016. The presentation will briefly explain the Coriolis flowmeter's principle and display the February 2016 performance tests' results. The expected incidence on zero pressure balloons' trajectories will also be discussed based on simulations ran on a balloon flight simulator software.

  11. Determination of alcohol sulfates in wastewater treatment plant influents and effluents by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Fernández-Ramos, C; Ballesteros, O; Blanc, R; Zafra-Gómez, A; Jiménez-Díaz, I; Navalón, A; Vílchez, J L

    2012-08-30

    In the present paper, we developed an accurate method for the analysis of alcohol sulfates (AS) in wastewater samples from wastewater treatment plant (WWTP) influents and effluents. Although many methodologies have been published in the literature concerning the study of anionic surfactants in environmental samples, at present, the number of analytical methodologies that focus in the determination of AS by gas chromatography in the different environmental compartments is limited. The reason for this is that gas chromatography-mass spectrometry (GC-MS) technique requires a previous hydrolysis reaction followed by derivatization reactions. In the present work, we proposed a new procedure in which the hydrolysis and derivatization reactions take place in one single step and AS are directly converted to trimethylsilyl derivatives. The main factors affecting solid-phase extraction (SPE), hydrolysis/derivatization and GC-MS procedures were accurately optimised. Quantification of the target compounds was performed by using GC-MS in selected ion monitoring (SIM) mode. The limits of detection (LOD) obtained ranged from 0.2 to 0.3 μg L(-1), and limits of quantification (LOQ) from 0.5 to 1.0 μg L(-1), while inter- and intra-day variability was under 5%. A recovery assay was also carried out. Recovery rates for homologues in spiked samples ranged from 96 to 103%. The proposed method was successfully applied for the determination of anionic surfactants in wastewater samples from one WWTP located in Granada (Spain). Concentration levels for the homologues up to 39.4 μg L(-1) in influent and up to 8.1 μg L(-1) in effluent wastewater samples.

  12. [Determination of glyphosate and aminomethylphosphonic acid residues in foods using high performance liquid chromatography-mass spectrometry/mass spectrometry].

    Science.gov (United States)

    Li, Bo; Deng, Xiaojun; Guo, Dehua; Jin, Shuping

    2007-07-01

    A method for the determination of glyphosate (PMG) and aminomethylphosphonic acid (AMPA) residues in plant products, such as rice, wheat, vegetables, fruits and tea, pig and chicken muscles, aquatic products, chestnut, honey, etc., was developed using high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). In this method, PMG and AMPA were extracted with water from samples, defatted using an extraction step with dichloromethane, and purified using a cation-exchange (CAX) solid phase extraction cartridge. Then, these were derived using fluorenylmethylchloroformate (FMOC-Cl) in borate buffer for subsequent HPLC-MS/MS analysis. Isotope-labeled PMG 1, 2(13)- C(15) N was used as the internal standard for the quantitative analysis of two residues. For all samples, the recoveries ranged from 80.0% to 104% and the relative standard deviations (RSDs) ranged from 6.7% to 18.2%. The limit of quantification (LOQ) was determined to be 0.05 mg/kg with a linear range of 0.20-10 microg/L. It is demonstrated that this method is reliable and sensitive for the analysis of PMG and APMA with low concentrations in foods.

  13. A LEGO Watt balance: An apparatus to determine a mass based on the new SI

    Science.gov (United States)

    Chao, L. S.; Schlamminger, S.; Newell, D. B.; Pratt, J. R.; Seifert, F.; Zhang, X.; Sineriz, G.; Liu, M.; Haddad, D.

    2015-11-01

    A global effort to redefine our International System of Units (SI) is underway, and the change to the new system is expected to occur in 2018. Within the newly redefined SI, the present base units will still exist but be derived from fixed numerical values of seven reference constants. In particular, the unit of mass (the kilogram) will be realized through a fixed value of the Planck constant h. A so-called watt balance, for example, can then be used to realize the kilogram unit of mass within a few parts in 108. Such a balance has been designed and constructed at the National Institute of Standards and Technology. For educational outreach and to demonstrate the principle, we have constructed a LEGO tabletop watt balance capable of measuring a gram-level masses to 1% relative uncertainty. This article presents the design, construction, and performance of the LEGO watt balance and its ability to determine h.

  14. Determination of macrolide antibiotics in chicken tissues by liquid chromatography-electrospray mass spectrometry

    Science.gov (United States)

    Salikin, Jamilah; Abdullah, Aminah

    2013-11-01

    A methodusingliquid chromatography-electrospray mass spectrometry (LC-(ESI)MS) for the simultaneous determination of three macrolides (tylosin, spiramycin and tilmicosin) in poultry muscle has been developed. The drugs were extracted with EDTA McIlvaine buffer, filter through celite 545 and the extracts were cleaned up by SPE Oasis HLB cartridge. Separation was carried out in end-capped silica-based C18 column and mobile phases containing trifluoroacetic acid-acetonitrile with a binary gradient system at a flow rate 0.5 ml/min. Detection was performed by single mass spectrometry with electrospray ionization in the positive mode. Several parameters affecting the mass spectra were studied. Chicken samples from the market were analyzed to check the residue of macrolide antibiotics.

  15. Precision W-boson and top-quark mass determinations at a muon collider

    CERN Document Server

    Barger, V; Gunion, J F; Han, T

    1997-01-01

    Precise determinations of the masses of the $W$ boson and of the top qu= ark could stringently test the radiative structure of the Standard Model (SM)= or provide evidence for new physics. We analyze the excellent prospects at a= muon collider for measuring $M_W$ and $m_t$ in the $W^+W^-$ and $t\\bar t$ thre= shold regions. With an integrated luminosity of 10 (100) fb$^{-1}$, the $W$-bos= on mass could be measured to a precision of 20 (6) MeV, and the top-quark ma= ss to a precision of 200 (70) MeV, provided that theoretical and experimental systematics are understood. A measurement of $\\Delta m_t=3D200$ MeV for f= ixed $M_W$ would constrain a 100 GeV SM Higgs mass within about $\\pm 2$ GeV, w= hile 10$ GeV.

  16. Stereophotogrammetrie Mass Distribution Parameter Determination Of The Lower Body Segments For Use In Gait Analysis

    Science.gov (United States)

    Sheffer, Daniel B.; Schaer, Alex R.; Baumann, Juerg U.

    1989-04-01

    Inclusion of mass distribution information in biomechanical analysis of motion is a requirement for the accurate calculation of external moments and forces acting on the segmental joints during locomotion. Regression equations produced from a variety of photogrammetric, anthropometric and cadaeveric studies have been developed and espoused in literature. Because of limitations in the accuracy of predicted inertial properties based on the application of regression equation developed on one population and then applied on a different study population, the employment of a measurement technique that accurately defines the shape of each individual subject measured is desirable. This individual data acquisition method is especially needed when analyzing the gait of subjects with large differences in their extremity geo-metry from those considered "normal", or who may possess gross asymmetries in shape in their own contralateral limbs. This study presents the photogrammetric acquisition and data analysis methodology used to assess the inertial tensors of two groups of subjects, one with spastic diplegic cerebral palsy and the other considered normal.

  17. Determining the neutrino mass hierarchy with INO, T2K, NOvA and reactor experiments

    Science.gov (United States)

    Ghosh, Anushree; Thakore, Tarak; Choubey, Sandhya

    2013-04-01

    The relatively large measured value of θ 13 has opened up the possibility of determining the neutrino mass hierarchy through earth matter effects. Amongst the current accelerator-based experiments only NOvA has a long enough baseline to observe earth matter effects. However, NOvA is plagued with uncertainty on the knowledge of the true value of δ CP, and this could drastically reduce its sensitivity to the neutrino mass hierarchy. The earth matter effect on atmospheric neutrinos on the other hand is almost independent of δ CP. The 50 kton magnetized Iron CALorimeter at the India-based Neutrino Observatory (ICAL@INO) will be observing atmospheric neutrinos. The charge identification capability of this detector gives it an edge over others for mass hierarchy determination through observation of earth matter effects. We study in detail the neutrino mass hierarchy sensitivity of the data from this experiment simulated using the NUANCE based generator developed for ICAL@INO and folded with the detector resolutions and efficiencies obtained by the INO collaboration from a full Geant4-based detector simulation. The data from ICAL@INO is then combined with simulated data from T2K, NOvA, Double Chooz, RENO and Daya Bay experiments and a combined sensitivity study to the mass hierarchy is performed. With 10 years of ICAL@INO data combined with T2K, NOvA and reactor data, one could get about 2.3 σ-5.7 σ discovery of the neutrino mass hierarchy, depending on the true value of sin2 θ 23 [0.4-0.6], sin2 2 θ 13 [0.08-0.12] and δ CP [0-2 π].

  18. [Determination of imidaclothiz in tea by QuEChERS cleanup and liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Liu, Songnan; Zhao, Xinying; Dong, Xiaoqian; Xu, Wenwen; Zhao, Rong

    2015-11-01

    The method for the determination of imidaclothiz residue in tea by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. The imidaclothiz in tea was extracted by acetonitrile and purified by QuEChERS with PSA (primary secondary amine), C18, GCB (graphitized carbon black) as the adsorbents. The purified solution was centrifuged and the supernatant was diluted with water of equal volume. The separation was performed on a C18 column with a gradient elution program of acetonitrile (containing 0.1% (v/v) formic acid) and water at a flow rate of 0.30 mL/min. The mass spectrometer was carried out with electrospray ion source in the positive mode (ESI+) and selective reaction monitoring (SRM), quantified by external standard solution. The results showed that the mass concentration of imidaclothiz in the range of 1 to 500 μg/L was linearly correlated with the peak area, and the correlation coefficient (r) was 0.999 9. The limit of quantification (LOQ, S/N ≥ 10) was 0.01 mg/kg. The recoveries in oolong tea and green tea at three spiked levels (0.01, 0.3 and 3 mg/kg) varied from 87.0%-101.0% and the relative standard deviations (RSDs, n = 7) were between 2.1% and 13.1%. The real sample tests showed that the method is simple, cheap, accurate, specific, rapid, and suitable for the qualitative and quantitative confirmation of imidaclothiz residue in tea.

  19. Determination of the neutron mass; Determinacion de la masa del neutron

    Energy Technology Data Exchange (ETDEWEB)

    Amador V, P.; Chacon R, A.; Arcos P, A.; Rodriguez N, S.; Pinedo S, A.; Vega C, H.R. [Unidad Academica de Estudios Nucleares, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)]. e-mail: paus2281@yahoo.com.mx

    2005-07-01

    The binding energy of the deuteron was measured and it was determined the neutron mass starting from the nuclear reaction, {sup 1}{sub 0} n + {sup 1}{sub 1} H {yields}{sup 2}{sub 1} D + {gamma}. The produced photon is soon a gamma ray that is emitted when the hydrogen captures a thermal neutron. The photon energy was measured using two spectrometric systems for gamma rays. A system with a detector of NaI(TI) of 3'' x 3'' and the other one with a High-purity Germanium detector. The first detector has a bigger efficiency and a smaller resolution in comparison with the second detector. The energy of the measured photon is the binding energy of the deuteron. With the measurement of the photon energy and the masses of the proton and of the deuterium it was determined the neutron mass. The value of the mass obtained with both systems it was compared with the value reported in the literature. The nuclear reaction was induced in a volume of paraffin that it was bombing with a source {sup 239} PuBe whose activity is of 3.7 x 10{sup 10} Bq. (Author)

  20. Determining the Neutrino Mass Hierarchy with INO, T2K, NOvA and Reactor Experiments

    CERN Document Server

    Ghosh, Anushree; Choubey, Sandhya

    2012-01-01

    The relatively large measured value of $\\theta_{13}$ has opened up the possibility of determining the neutrino mass hierarchy through earth matter effects. Amongst the current accelerator-based experiments only NOvA has a long enough baseline to observe earth matter effects. However, NOvA is plagued with uncertainty on the knowledge of the true value of $\\delta_{CP}$, and this could drastically reduce its sensitivity to the neutrino mass hierarchy. The earth matter effect on atmospheric neutrinos on the other hand is almost independent of $\\delta_{CP}$. The 50 kton magnetized Iron CALorimeter at the India-based Neutrino Observatory (ICAL@INO) will be observing atmospheric neutrinos. The charge identification capability of this detector gives it an edge over others for mass hierarchy determination through observation of earth matter effects. We study in detail the neutrino mass hierarchy sensitivity of the data from this experiment simulated using the Nuance based generator developed for ICAL@INO and folded wi...

  1. [Determination of 14 mycotoxins in Chinese herbs by liquid chromatography-tandem mass spectrometry with immunoaffinity purification].

    Science.gov (United States)

    Ge, Baokun; Zhao, Kongxiang; Wang, Wei; Mi, Jiebo

    2011-06-01

    A method was developed for the determination of 14 mycotoxins, aflatoxins, T-2, HT-2, fumonisins, ochratoxin A, zearalenone, etc. in Chinese herbs by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). The sample was extracted with phosphate buffer solution (PBS) and methanol in turn, and then purified by a high selective multi-functional immunoaffinity column. The column was washed by PBS (containing 0.1% Twain) and water, and then eluted by methanol. The eluate was dried under nitrogen, dissolved in methanol-10 mmol/L NH4Ac (40 : 60, v/v) solution. The mycotoxins were separated on a Waters Xterra C18 MS column (100 mm x 2.1 mm, 3.5 microm) and detected by MS/MS. The limits of quantification (LOQs) of the 14 mycotoxins were from 1.0 to 5.0 microg/kg. The average recoveries of the 14 mycotoxins spiked in Chinese herbs (Ginseng, Campanulaceae, Radix and Ophiopogonis) ranged from 71.9% to 99.7% at the three spiked levels of 1.0, 5.0, 10.0 microg/kg, and the relative standard deviations (RSDs, n = 6) were between 4.8% and 15.8%. The method is rapid, sensitive and accurate, and suitable for the determination of the 14 mycotoxins in Chinese medicines. The quantification limits of aflatoxins can meet the domestic and foreign requirements.

  2. [Determination of dimethyl fumarate in leather and textiles by gas chromatography-tandem mass spectrometry with solid phase extraction].

    Science.gov (United States)

    Zhao, Yang; Qi, Xiaoxia

    2010-01-01

    An effective method for the determination of dimethyl fumarate (DMF) in leather and textiles by gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed. Samples of leather or textiles were extracted with ethyl acetate and concentrated, DMF was separated on a VF-5 ms column and analyzed by GC-MS/MS after solid phase extraction (SPE) process. The result shows that this method is sensitive, accurate and reliable. The linear relationship was perfect and the interference with background signal was further eliminated after pretreatment, SPE and GC-MS/MS analytical conditions were optimized. The average recoveries of DMF in leather and textiles at three levels ranged from 84% to 93%, the relative standard deviations (n = 6) were lower than 7.2%, the limits of detection in the range from 0.012 to 0.039 mg/kg (S/N = 3) , the correlation coefficient was 0.999 0 over the range 0.05 - 100 mg/L. It has been applied to routine determination of DMF in leather and textiles with satisfactory results.

  3. [Simultaneous determination of 11 bisphenols in plastic bottled drinking water by ultra performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Gou, Xinlei; Gao, Xia; Hu, Guanghui; Chi, Haitao; Le, Shengfeng; Wang, Wei; Liu, Weili

    2014-09-01

    A sensitive method was developed for the simultaneous determination of 11 bisphenols in plastic bottled drinking water by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were freeze-dried under vacuum and then dissolved with methanol. The separation was performed on a UPLC BEH C18 column (100 mm x 2.1 mm, 1.7 μm) by using 0.1% (v/v) NH3 · H2O and methanol as mobile phases with gradient elution at a flow rate of 0.2 mL/min. The electrospray ionization (ESI) source in negative ion mode was used for the analysis of the 11 bisphenols in the multiple reaction monitoring (MRM) mode. The results verified that the standard curves for the 11 bisphenols were obtained with good correlation coefficients (R2) > 0.997 in their concentration ranges. The limits of detection (LOD, S/N = 3) for the 11 bisphenols were in the range of 0.01-1.00 μg/L. The mean recoveries for the 11 bisphenols at three spiked levels (low, middle, high) were 75.3%-102.1% with the relative standard deviations of 1.5%-8.9%. Seven plastic bottled drinking water samples were tested, and no bisphenol was found. The method is accurate, simple, rapid and feasible for the simultaneous determination of bisphenols in plastic bottled drinking water.

  4. [Determination of 16 pesticide residues in fruits and vegetables by QuEChERS-liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Wu, Yan; Jiang, Bing; Xu, Yigang; Zhao, Wei; Meng, Xiangrui; Zhou, Yuan; Yu, Jiahui; Zu, Yuangang

    2015-03-01

    A sensitive and convenient liquid chromatography-tandem mass spectrometric method was developed for the determination of 16 pesticides such as imidacloprid, prochloraz, difenoconazole, azoxystrobin, and thiamethoxam in fruits and vegetables. After compared with methanol and acetone-cyclohexane (1:2, v/v), acetonitrile was chosen as the extraction solvent. The samples were extracted by acetonitrile in high-speed homogenization. The extraction solution was cleaned up by liquid-liquid extraction, and the supernatant was collected. In this work, QuEChERS exhibited much higher efficiency than Carbon-NH2 solid-phase extraction in purification. The pigments and organic acids were removed by purge line (150 mg primary secondary amine (PSA) sorbent and 900 mg absolute magnesium sulfate), leading to the decrease of the background interferences. The average recoveries of the 16 pesticides were almost in the range of 75%-111% at the three spiked levels, and the relative standard deviations were less than 16%. The qualitative analysis and quantitative analysis were investigated by LC-MS/MS and matrix-matched calibration curves. The results showed that the method of QuEChERS combined with LC-MS/MS is rapid, accurate and sensitive for the determination of the 16 pesticide residues in fruits and vegetables.

  5. [Determination of bisphenol A from toys and food contact materials by derivatization and gas chromatography-mass spectrometry].

    Science.gov (United States)

    Gao, Yonggang; Zhang, Yanyan; Gao, Jianguo; Zhang, Huiling; Zheng, Lisha; Chen, Jing

    2012-10-01

    A method was developed for the determination of bisphenol A (BPA) in toys and food contact materials. The BPA was extracted with Soxhlet extraction method from the sample and reacted with acetic anhydride. The final product was determined by gas chromatography-mass spectrometry (GC-MS). To achieve the optimum derivatization performance, the derivatization time and dosage of derivatization reagent etc. were investigated. Under the optimized experimental conditions, the final product was stable and the peak shape was good. The linearity of the derivative was good in the range of 0.05 to 50 mg/L with the correlation coefficient (r2) above 0.999. The recoveries ranged from 80% to 93% at the spiked levels of 0.05, 1.00, 10.00 mg/kg with the relative standard deviations (RSDs) less than 3.7%. The limit of detection (S/N = 3) was 10 microg/kg. The method is accurate and has high recovery. The method is suitable for the inspection of bisphenol A in toys and food contact materials.

  6. Native and mass labeled [13C14]-decabromodiphenylethane (DBDPE). Characterization and use in determination of DBDPE in sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    McCrindle, R. [Guelph Univ., ON (Canada). Chemistry Dept.; Chittim, B.; Konstantinov, A.; McAlees, A.; Potter, D.; Tashiro, C.; Yeo, B. [Wellington Laboratories, Guelph, ON (Canada); Kolic, T.; MacPherson, K.; Reiner, E. [Ontario Ministry of the Environment, Toronto, ON (Canada)

    2004-09-15

    Decabromodiphenylethane (DBDPE) is a relatively new brominated flame retardant for use in polystyrene and polyolefin-based thermoplastic formulations. DBDPE was introduced in the early 90's, and is marketed as a non-diphenyl oxide based alternative to brominated diphenyl ethers (BDE)i. One study has shown that DBDPE produces no dioxins and only minor quantities of 2,3,7,8-TBDF under pyrolysis conditions. Although currently DBDPE is not as widely used as decabromodiphenyl ether (BDE-209) because of the higher cost, it is predicted that DBDPE will soon become one of the major flame retardants used by the thermoplastics industry. The presence of DBDPE in sediments, sewage sludge and air samples was reported during Dioxin 2003. The levels of DBDPE found in sewage sludge ranged from 33 to approximately 100 ng/g dry weight, and its ratio to BDE-209 levels in quantified samples was 0.01 in the sediment and 0.3 to 0.6 in the sewage sludge samples examined. The lack of a surrogate standard for DBDPE definitely poses difficulties in determining levels accurately. This study has two goals: the characterization of mass-labeled DBDPE and an assessment of its utility in determining DBDPE levels in environmental samples.

  7. In-situ determination of field-scale NAPL mass transfer coefficients: Performance, simulation and analysis.

    Science.gov (United States)

    Mobile, Michael; Widdowson, Mark; Stewart, Lloyd; Nyman, Jennifer; Deeb, Rula; Kavanaugh, Michael; Mercer, James; Gallagher, Daniel

    2016-04-01

    Better estimates of non-aqueous phase liquid (NAPL) mass, its persistence into the future, and the potential impact of source reduction are critical needs for determining the optimal path to clean up sites impacted by NAPLs. One impediment to constraining time estimates of source depletion is the uncertainty in the rate of mass transfer between NAPLs and groundwater. In this study, an innovative field test is demonstrated for the purpose of quantifying field-scale NAPL mass transfer coefficients (kl(N)) within a source zone of a fuel-contaminated site. Initial evaluation of the test concept using a numerical model revealed that the aqueous phase concentration response to the injection of clean groundwater within a source zone was a function of NAPL mass transfer. Under rate limited conditions, NAPL dissolution together with the injection flow rate and the radial distance to monitoring points directly controlled time of travel. Concentration responses observed in the field test were consistent with the hypothetical model results allowing field-scale NAPL mass transfer coefficients to be quantified. Site models for groundwater flow and solute transport were systematically calibrated and utilized for data analysis. Results show kl(N) for benzene varied from 0.022 to 0.60d(-1). Variability in results was attributed to a highly heterogeneous horizon consisting of layered media of varying physical properties.

  8. In-situ determination of field-scale NAPL mass transfer coefficients: Performance, simulation and analysis

    Science.gov (United States)

    Mobile, Michael; Widdowson, Mark; Stewart, Lloyd; Nyman, Jennifer; Deeb, Rula; Kavanaugh, Michael; Mercer, James; Gallagher, Daniel

    2016-04-01

    Better estimates of non-aqueous phase liquid (NAPL) mass, its persistence into the future, and the potential impact of source reduction are critical needs for determining the optimal path to clean up sites impacted by NAPLs. One impediment to constraining time estimates of source depletion is the uncertainty in the rate of mass transfer between NAPLs and groundwater. In this study, an innovative field test is demonstrated for the purpose of quantifying field-scale NAPL mass transfer coefficients (klN) within a source zone of a fuel-contaminated site. Initial evaluation of the test concept using a numerical model revealed that the aqueous phase concentration response to the injection of clean groundwater within a source zone was a function of NAPL mass transfer. Under rate limited conditions, NAPL dissolution together with the injection flow rate and the radial distance to monitoring points directly controlled time of travel. Concentration responses observed in the field test were consistent with the hypothetical model results allowing field-scale NAPL mass transfer coefficients to be quantified. Site models for groundwater flow and solute transport were systematically calibrated and utilized for data analysis. Results show klN for benzene varied from 0.022 to 0.60 d- 1. Variability in results was attributed to a highly heterogeneous horizon consisting of layered media of varying physical properties.

  9. Determination of trace multi-elements in coal fly ash by inductively coupled plasma mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    XIE Hua-lin; TANG You-gen; LI Yu-jie; LI Li-bo

    2007-01-01

    The contents of Cr,Cu, Ni, As, Cd and Pb in coal fly ash were determined by a high resolution inductively coupled plasma mass spectrometry method.The sample digestions were performed in closed microwave vessels with HN03, HClO4 and HF.The optimum conditions for the determination were obtained.The applicability of the proposed method was validated by the analysis of coal fly ash reference material (NIST SRM 1633a). The results show that most of the spectral interferences can be avoided by measuring in the high resolution mode(maximum mass resolution R=9 000).The detection limit is from 0.05 to 0.21μg/g,and the precision is fine with relative standard deviation less than 4.3%.

  10. Determination of Rock Mass Modulus Using the Plate Loading Method at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Finley, R.E.; George, J.T.; Riggins, M.

    1999-08-02

    A suite of plate loading tests has recently been conducted by Sandia National Laboratories at the Exploratory Studies Facility at Yucca Mountain, Nevada. Fielding of these in situ tests as well as other approaches undertaken for the determination of rock mass modulus are described. The various methodologies are evaluated and their data compared. Calculation by existing empirical methods and numerical modeling are compared to each other as well as to field data.

  11. Determination of diclofenac concentrations in human plasma using a sensitive gas chromatography mass spectrometry method

    OpenAIRE

    2016-01-01

    Background A gas chromatography mass spectrometry (GCMS) method for the determination of diclofenac in human plasma has been developed and validated. Results This method utilizes hexane which is a relatively less toxic extraction solvent compared to heptane and benzene. In addition, phosphoric acid and acetone were added to the samples as deproteination agents, which increased the recovery of diclofenac. These revised processes allow clean extraction and near-quantitative recovery of analyte ...

  12. Determination of diclofenac concentrations in human plasma using a sensitive gas chromatography mass spectrometry method

    OpenAIRE

    Shah, Iltaf; Barker, James; Naughton, Declan P; Barton, Stephen J.; Ashraf, Syed Salman

    2016-01-01

    Background\\ud A gas chromatography mass spectrometry (GCMS) method for the determination of diclofenac in human plasma has been developed and validated.\\ud \\ud Results\\ud This method utilizes hexane which is a relatively less toxic extraction solvent compared to heptane and benzene. In addition, phosphoric acid and acetone were added to the samples as deproteination agents, which increased the recovery of diclofenac. These revised processes allow clean extraction and near-quantitative recover...

  13. Determination of Alkyl Methanesulfonates in Doxazosin Mesylate by Gas Chromatography-mass Spectrometer

    OpenAIRE

    C Sitaram; Rupakula, R. B.; B N Reddy; Sastry, C. S. P

    2011-01-01

    High sensitive rapid gas chromatography-mass spectrometry method for the determination of four carcinogenic alkyl methanesulfonates viz. methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate in doxazosin mesylate has been presented by using selective ion monitoring mode. The optimum separation was achieved between methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate on a DB-5 (30 m×0.32 mm×1...

  14. Determination of the neutrino mass hierarchy with a new statistical method

    CERN Document Server

    Stanco, L; Tenti, M

    2016-01-01

    Neutrino physics is nowadays undergoing a change of perspectives, the discovery period is almost over and we are entering the phase of precise measurements. Despite the limited statistics collected for some variables, the three--flavour neutrino framework seems well consolidating. In this framework a new method has been developed to determine the neutrino mass ordering, one of the still unknown and most relevant parameters. The method is applied to the 2015 results of the NOvA experiment for $\

  15. Simultaneous determination of seventeen mycotoxins residues in Puerariae lobatae radix by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Wang, Shufang; Cheng, Ling; Ji, Shen; Wang, Ke

    2014-09-01

    This work reported an efficient and accurate liquid chromatography tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of seventeen mycotoxins in Puerariae lobatae radix, a frequently used traditional Chinese medicine (TCM). The effects of four different clean-up methods, including TC-M160, TC-T220, Mycosep 227, and QuEChERS method, on the recoveries of mycotoxins were investigated and compared. Finally, TC-M160 was chosen for better recovery and repeatability for mycotoxins analysis. The analytes were separated on an Agilent ZORBAX SB C18 column (4.6mm×250mm, 5μm particle size), and eluted with a mobile phase consisting of (A) water containing 0.1% formic acid and (B) acetonitrile containing 0.1% formic acid at a flow rate of 0.6mL/min. The separated compounds were detected by a triple quadrupole mass spectrometer operating in positive electrospray ionization with multiple reaction monitoring (MRM) mode. The results of method validation accorded with the requirement of analytical method for mycotoxins in COMMISSION REGULATION (EC) No 401/2006. The developed method was successfully applied for determination of mycotoxins in seventeen batches of Puerariae lobatae radix collected from different provinces of China. Three batches of them were found with contamination of mycotoxins AFB1 at (0.751±0.176)μg/kg, T-2 at (1.10±0.01)μg/kg, and T-2 at (0.853±0.044)μg/kg, respectively. The results demonstrated that the proposed method was suitable for monitoring mycotoxins residues in Puerariae lobatae radix.

  16. Determination of endocrine-disrupting compounds in drinking waters by fast liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Magi, Emanuele; Scapolla, Carlo; Di Carro, Marina; Liscio, Camilla

    2010-09-01

    Growing attention has been recently paid to safety of food and drinking water, making necessary the adoption of policies for water sources protection and the development of sensitive and rapid analytical methods to identify micropollutants. Endocrine-disrupting compounds (EDCs) have emerged as a major issue as they alter the functioning of the endocrine system. Since ingestion of EDCs via food is considered the major exposure route, there is a growing interest in understanding EDC fate during drinking water treatment and in monitoring potential contamination of surface waters and groundwaters. In this work, a fast liquid chromatography-electrospray ionization-tandem mass spectrometry method was developed for the determination of 4-n-nonylphenol (NP), bisphenol A (BPA), estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in drinking waters. In the literature analytical articles seldom provide details regarding fragmentation pathways. In this paper spectra of the five EDCs in negative ESI were interpreted with the support of accurate mass spectra acquired by a quadrupole time-of-flight instrument; fragmentation pathways were also proposed. The chromatographic separation of EDCs was optimized on a Pinnacle DB Biphenylic column with a water-acetonitrile gradient. Quantitative analysis was performed in multiple reaction monitoring (MRM) mode using bisphenol A-d(16) (BPA-d(16)) as internal standard; calibration curves showed good correlation coefficients (0.9989-0.9997). All figures of merit of the method were satisfactory; limits of detection were in the range 0.2-0.4 ng/ml. The method was applied to the determination of the analytes in waters sampled by polar organic chemical integrative samplers in a drinking water treatment plant. Rather low concentration of BPA, NP and E1 were measured in the inlet, while none of the considered EDCs was detected in the outlet.

  17. Specific determination of benzene in urine using dynamic headspace and mass-selective detection.

    Science.gov (United States)

    Ljungkvist, G; Lärstad, M; Mathiasson, L

    1999-01-08

    A method for the determination of benzene in urine was developed, based on dynamic headspace and preconcentration of the analyte on a solid sorbent. The subsequent analysis by thermal desorption of the sorbent, capillary gas chromatography and mass-selective detection ascertained a low limit of detection (6.5 ng/l) and a highly specific determination. The limit of detection is an order of magnitude lower than that reported earlier and allows reliable quantitation of occupational exposure and of most environmental exposures. Samples could be stored frozen for at least a month without significant loss.

  18. Improved statistical determination of absolute neutrino masses via radiative emission of neutrino pairs from atoms

    Science.gov (United States)

    Zhang, Jue; Zhou, Shun

    2016-06-01

    The atomic transition from an excited state |e ⟩ to the ground state |g ⟩ by emitting a neutrino pair and a photon, i.e., |e ⟩→|g ⟩+|γ ⟩+|νi⟩+|ν¯j⟩ with i , j =1 , 2, 3, has been proposed by Yoshimura and his collaborators as an alternative way to determine the absolute scale m0 of neutrino masses. More recently, a statistical analysis of the fine structure of the photon spectrum from this atomic process has been performed [N. Song et al. Phys. Rev. D 93, 013020 (2016)] to quantitatively examine the experimental requirements for a realistic determination of absolute neutrino masses. In this paper, we show how to improve the statistical analysis and demonstrate that the previously required detection time can be reduced by one order of magnitude for the case of a 3 σ determination of m0˜0.01 eV with an accuracy better than 10%. Such an improvement is very encouraging for further investigations on measuring absolute neutrino masses through atomic processes.

  19. Position determination and measurement error analysis for the spherical proof mass with optical shadow sensing

    Science.gov (United States)

    Hou, Zhendong; Wang, Zhaokui; Zhang, Yulin

    2016-09-01

    To meet the very demanding requirements for space gravity detection, the gravitational reference sensor (GRS) as the key payload needs to offer the relative position of the proof mass with extraordinarily high precision and low disturbance. The position determination and error analysis for the GRS with a spherical proof mass is addressed. Firstly the concept of measuring the freely falling proof mass with optical shadow sensors is presented. Then, based on the optical signal model, the general formula for position determination is derived. Two types of measurement system are proposed, for which the analytical solution to the three-dimensional position can be attained. Thirdly, with the assumption of Gaussian beams, the error propagation models for the variation of spot size and optical power, the effect of beam divergence, the chattering of beam center, and the deviation of beam direction are given respectively. Finally, the numerical simulations taken into account of the model uncertainty of beam divergence, spherical edge and beam diffraction are carried out to validate the performance of the error propagation models. The results show that these models can be used to estimate the effect of error source with an acceptable accuracy which is better than 20%. Moreover, the simulation for the three-dimensional position determination with one of the proposed measurement system shows that the position error is just comparable to the error of the output of each sensor.

  20. Determination of Sex Hormones in Antler Velvet by High Performance Liquid Chromatography Tandem Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    LU Chun-mei; WANG Ming-tai; MU Jun; BAI Yu-ping; DU Jian-shi; ZHANG Han-qi; WANG Jian-wei

    2012-01-01

    Eighteen sex hormones in antler velvet were determined by high performance liquid chromatography tandem mass spectrometry.The solid phase extraction was applied to eliminating the matrix effect.The experimental conditions were examined and optimized.Under the optimal conditions,the proposed method provides the good linearities and determination limits(0.2-1.0 μg/kg)of the analytes investigated.The recoveries ranging from 72.3% to 149.5% were obtained for the target analytes at two concentration levels.This method was applied to the determination of eighteen sex hormones in different kinds of antler velvet samples and the obtained results are satisfactory.The results indicate that the proposed method is suitable for the determination of sex hormones in antler velvet samples.

  1. Measurement uncertainty of isotopologue fractions in fluxomics determined via mass spectrometry.

    Science.gov (United States)

    Guerrasio, R; Haberhauer-Troyer, C; Steiger, M; Sauer, M; Mattanovich, D; Koellensperger, G; Hann, S

    2013-06-01

    Metabolic flux analysis implies mass isotopomer distribution analysis and determination of mass isotopologue fractions (IFs) of proteinogenic amino acids of cell cultures. In this work, for the first time, this type of analysis is comprehensively investigated in terms of measurement uncertainty by calculating and comparing budgets for different mass spectrometric techniques. The calculations addressed amino acids of Pichia pastoris grown on 10% uniformly (13)C labeled glucose. Typically, such experiments revealed an enrichment of (13)C by at least one order of magnitude in all proteinogenic amino acids. Liquid chromatography-time-of-flight mass spectrometry (LC-TOFMS), liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) analyses were performed. The samples were diluted to fit the linear dynamic range of the mass spectrometers used (10 μM amino acid concentration). The total combined uncertainties of IFs as well as the major uncertainty contributions affecting the IFs were determined for phenylalanine, which was selected as exemplary model compound. A bottom-up uncertainty propagation was performed according to Quantifying Uncertainty in Analytical Measurement and using the Monte Carlo method by considering all factors leading to an IF, i.e., the process of measurement and the addition of (13)C-glucose. Excellent relative expanded uncertainties (k = 1) of 0.32, 0.75, and 0.96% were obtained for an IF value of 0.7 by LC-MS/MS, GC-MS, and LC-TOFMS, respectively. The major source of uncertainty, with a relative contribution of 20-80% of the total uncertainty, was attributed to the signal intensity (absolute counts) uncertainty calculated according to Poisson counting statistics, regardless which of the mass spectrometry platforms was used. Uncertainty due to measurement repeatability was of importance in LC-MS/MS, showing a relative contribution up to 47% of the total uncertainty, whereas for GC-MS and LC

  2. Atmospheric-Pressure Chemical Ionization Tandem Mass Spectrometry (APGC/MS/MS) an Alternative to High-Resolution Mass Spectrometry (HRGC/HRMS) for the Determination of Dioxins

    NARCIS (Netherlands)

    Bavel, Van Bert; Geng, Dawei; Cherta, Laura; Nácher-Mestre, Jaime; Portolés, Tania; Ábalos, Manuela; Sauló, Jordi; Abad, Esteban; Dunstan, Jody; Jones, Rhys; Kotz, Alexander; Winterhalter, Helmut; Malisch, Rainer; Traag, Wim; Hagberg, Jessika; Ericson Jogsten, Ingrid; Beltran, Joaquim; Hernández, Félix

    2015-01-01

    The use of a new atmospheric-pressure chemical ionization source for gas chromatography (APGC) coupled with a tandem quadrupole mass spectrometry (MS/MS) system, as an alternative to high-resolution mass spectrometry (HRMS), for the determination of PCDDs/PCDFs is described. The potential of usin

  3. Determination of Ultralow Level 129I/127I in Natural Samples by Separation of Microgram Carrier Free Iodine and Accelerator Mass Spectrometry Detection

    DEFF Research Database (Denmark)

    Hou, Xiaolin; Zhou, Weijian; Chen, Ning;

    2010-01-01

    a carrier free method using coprecipitation of AgI with AgCl for preparing micrograms of iodine target, associated with combustion using a tube furnace for separating iodine from solid samples and anion exchange chromatography for preconcentrating iodine from a large volume of water. An accelerator mass...... of 129I/127I, and a detection limit of this method for 129I is calculated to be 105 atoms. This will allow us to accurately determine 129I in prenuclear geological samples of low iodine concentration with 129I/127I of 10−12, such as loess, soil, coral, rock, sediment, and groundwater. Some samples...

  4. High-field asymmetric waveform ion mobility spectrometry for determining the location of in-source collision-induced dissociation in electrospray ionization mass spectrometry.

    Science.gov (United States)

    Xia, Yuan-Qing; Jemal, Mohammed

    2009-09-15

    The understanding and control of the in-source collision-induced dissociation (CID) of analytes is important for the accurate LC-MS/MS quantitation of drugs and metabolites in biological samples. Accordingly, it was of interest to us to establish whether such in-source CID takes place after and/or before the orifice of an electrospray ionization (ESI) mass spectrometer. A high-field asymmetric waveform ion mobility spectrometry (FAIMS) system that is physically located between the sprayer and the orifice of a mass spectrometer can serve as an ion filter to control ions entering the orifice of the mass spectrometer. In such a configuration, FAIMS could conceivably be used to determine if the in-source CID of an analyte occurs after and/or before the mass spectrometer orifice. We demonstrated this capability of FAIMS using ifetroban acylglucuronide metabolite as a model compound. Under the conditions used, the results showed that the in-source CID conversion of the acylglucuronide metabolite to its parent drug ifetroban occurred almost entirely after the orifice of the mass spectrometer, with the conversion upstream of the orifice accounting for only 5.6% of the conversion. Under the circumstance, the term "post-orifice CID" rather than "in-source CID" may be more appropriate in describing such a dissociation occurring in the front end of a mass spectrometer.

  5. Accurate Size and Size-Distribution Determination of Polystyrene Latex Nanoparticles in Aqueous Medium Using Dynamic Light Scattering and Asymmetrical Flow Field Flow Fractionation with Multi-Angle Light Scattering

    Directory of Open Access Journals (Sweden)

    Shinichi Kinugasa

    2012-01-01

    Full Text Available Accurate determination of the intensity-average diameter of polystyrene latex (PS-latex by dynamic light scattering (DLS was carried out through extrapolation of both the concentration of PS-latex and the observed scattering angle. Intensity-average diameter and size distribution were reliably determined by asymmetric flow field flow fractionation (AFFFF using multi-angle light scattering (MALS with consideration of band broadening in AFFFF separation. The intensity-average diameter determined by DLS and AFFFF-MALS agreed well within the estimated uncertainties, although the size distribution of PS-latex determined by DLS was less reliable in comparison with that determined by AFFFF-MALS.

  6. A Remote Laser-mass Spectrometer for Determination of Elemental Composition

    Science.gov (United States)

    Deyoung, R. J.; Situ, W.

    1993-01-01

    Determination of the elemental composition of lunar, asteroid, and planetary surfaces is a major concern for science and resource utilization of space. The science associated with the development of a satellite or lunar rover laser-mass spectrometer instrument is presented here. The instrument would include a pulsed laser with sufficient energy to create a plasma on a remote surface. Ions ejected from this plasma travel back to the spacecraft or rover, where they are analyzed by a time-of-flight mass spectrometer, giving the elemental and isotope composition. This concept is based on the LIMA-D instrument on board the former Soviet Union Phobos-88 spacecraft sent to Mars. A laser-mass spectrometer placed on a rover or satellite would substantially improve the data return over alternative techniques. The spatial resolution would be centimeters, and a complete mass spectrum could be achieved in one laser shot. An experiment is described that demonstrates these features. A 400 mj Nd:YAG laser is focused, to an intensity of 10(exp 11) w/sq cm, onto a Al, Ag, Cu, Ge, or lunar simulant target. A plasma forms from which ions are ejected. Some of these ions travel down an 18-m evacuated flight tube to a microchannel plate detector. Alternatively, the ions are captured by an ion trap where they are stored until pulsed into a 1-m time-of-flight mass spectrometer, giving the elemental composition of the remote surface. A television camera monitors the plasma plume shape, and a photodiode monitors the temporal plasma emission . With this system, ions of Al, Ag, Cu, Ge, and lunar simulant have been detected at 18 m. The mass spectrum from the ion trap and 1-m time-of-flight tube will be presented.

  7. Critical comparison of radiometric and mass spectrometric methods for the determination of radionuclides in environmental, biological and nuclear waste samples.

    Science.gov (United States)

    Hou, Xiaolin; Roos, Per

    2008-02-11

    The radiometric methods, alpha (alpha)-, beta (beta)-, gamma (gamma)-spectrometry, and mass spectrometric methods, inductively coupled plasma mass spectrometry, accelerator mass spectrometry, thermal ionization mass spectrometry, resonance ionization mass spectrometry, secondary ion mass spectrometry, and glow discharge mass spectrometry are reviewed for the determination of radionuclides. These methods are critically compared for the determination of long-lived radionuclides important for radiation protection, decommissioning of nuclear facilities, repository of nuclear waste, tracer application in the environmental and biological researches, these radionuclides include (3)H, (14)C, (36)Cl, (41)Ca, (59,63)Ni, (89,90)Sr, (99)Tc, (129)I, (135,137)Cs, (210)Pb, (226,228)Ra, (237)Np, (241)Am, and isotopes of thorium, uranium and plutonium. The application of on-line methods (flow injection/sequential injection) for separation of radionuclides and automated determination of radionuclides is also discussed.

  8. Determination of minimum mass and spatial location of initiator for detonation of propylene oxide aerosols

    Science.gov (United States)

    Apparao, A.; Saji, J.; Balaji, M.; Devangan, A. K.; Rao, C. R.

    2017-03-01

    The mishandling of liquid fuels during production, processing or transportation can lead to the formation of combustible two-phase mixtures. These mixtures, with the availability of a suitable energy source, may be ignited generating a deflagration, or even a detonation wave. For military applications, unconfined fuel aerosols are created and detonated with the help of a strong shock generated by a powerful energy source. The minimum energy requirement is expressed in terms of the shock strength, or mass of the high-explosive-based initiator. In this study, the detonability of unconfined aerosols of 4.3 kg propylene oxide was studied by positioning different quantities of cylindrical-shaped initiators of RDX/wax (95/5) at a fixed spatial location in the aerosol cloud, and the minimum mass of the initiator required for detonation initiation was determined. The effect of spatial location and the requirement of initiator mass, especially at farther locations where the fuel concentration is likely to be lower and closer to the lower explosive limit, was also investigated. The experimental findings help identify the detonable zone in unconfined propylene oxide aerosol clouds for different combinations of spatial location and mass of initiator.

  9. Determination of minimum mass and spatial location of initiator for detonation of propylene oxide aerosols

    Science.gov (United States)

    Apparao, A.; Saji, J.; Balaji, M.; Devangan, A. K.; Rao, C. R.

    2016-06-01

    The mishandling of liquid fuels during production, processing or transportation can lead to the formation of combustible two-phase mixtures. These mixtures, with the availability of a suitable energy source, may be ignited generating a deflagration, or even a detonation wave. For military applications, unconfined fuel aerosols are created and detonated with the help of a strong shock generated by a powerful energy source. The minimum energy requirement is expressed in terms of the shock strength, or mass of the high-explosive-based initiator. In this study, the detonability of unconfined aerosols of 4.3 kg propylene oxide was studied by positioning different quantities of cylindrical-shaped initiators of RDX/wax (95/5) at a fixed spatial location in the aerosol cloud, and the minimum mass of the initiator required for detonation initiation was determined. The effect of spatial location and the requirement of initiator mass, especially at farther locations where the fuel concentration is likely to be lower and closer to the lower explosive limit, was also investigated. The experimental findings help identify the detonable zone in unconfined propylene oxide aerosol clouds for different combinations of spatial location and mass of initiator.

  10. EXTRACTION, QUANTIFICATION, AND MOLAR MASS DETERMINATION OF HYALURONIC ACID EXTRACTED FROM CHICKEN CREST

    Directory of Open Access Journals (Sweden)

    C. S. ROSA

    2008-11-01

    Full Text Available

    Hyaluronic acid (HA is part of the connective tissue. The polymer is composed of alternating units of ß-d-glucuronic acid and N-acetyl-ß-d-glucosamine linked, respectively, via 1-3 and 1-4 bonds. The chicken crest is one of the richest tissues in this polysaccharide. Since Brazil is one of the main chicken exporters in the world, the utilization of the crests of abated animals for the HA obtaining is particularly attractive. The present work sought to extract HA from chicken crest and to determine the molar mass of the extracted acid. Extraction was accomplished by proteolytic digestion with papain during 24 h at 60oC, followed by precipitation with cetylpyridinium chloride (CPC. Hexuronic acid content was determined via the carbazole method, the intrinsic viscosity was measured using the ball viscosimeter, and the molar mass was calculated by extrapolating the calibration line to zero. In addition, qualitative infrared spectroscopy was carried out on the sample using the Bomem MB spectrophotometer. The results show that the extraction method was effective: the extracted acid possesses a large molecular mass, and the extract contains a signifi cant amount of HA.

  11. Revisiting rho 1 Cancri e: A New Mass Determination Of The Transiting super-Earth

    CERN Document Server

    Endl, Michael; Cochran, William D; MacQueen, Phillip J; Brugamyer, Erik J; Caldwell, Caroline; Wittenmyer, Robert A; Barnes, Stuart I; Gullikson, Kevin

    2012-01-01

    We present a mass determination for the transiting super-Earth rho 1 Cancri e based on nearly 700 precise radial velocity (RV) measurements. This extensive RV data set consists of data collected by the McDonald Observatory planet search and published data from Lick and Keck observatories (Fischer et al. 2008). We obtained 212 RV measurements with the Tull Coude Spectrograph at the Harlan J. Smith 2.7 m Telescope and combined them with a new Doppler reduction of the 131 spectra that we have taken in 2003-2004 with the High-Resolution-Spectrograph (HRS) at the Hobby-Eberly Telescope (HET) for the original discovery of rho 1 Cancri e. Using this large data set we obtain a 5-planet Keplerian orbital solution for the system and measure an RV semi-amplitude of K = 6.29 +/- 0.21 m/s for rho 1 Cnc e and determine a mass of 8.37 +/- 0.38 M_Earth. The uncertainty in mass is thus less than 5%. This planet was previously found to transit its parent star (Winn et al. 2011, Demory et al. 2011), which allowed them to estima...

  12. Determination of Candesartan in Human Plasma with Liquid Chromatography - Tandem Mass Spectrometry.

    Science.gov (United States)

    Forjan, Vanja; Cvitkovič Maričič, Lea; Prosen, Helena; Brodnjak Vončina, Darinka

    2016-01-01

    A sensitive, specific and rapid liquid chromatography - tandem mass spectrometry method was developed and validated for the determination of candesartan in human plasma. Analyte was separated from endogenous components present in plasma by solid phase extraction. Chromatographic separation was performed on Gemini C18 analytical column using mobile phase acetonitrile - 5 mM ammonium formate pH 2 (90:10, v/v) at flow rate of 0.3 mL/min. For detection, tandem mass spectrometry in SRM mode with positive electrospray ionization was used. The mass transitions m/z 441.1 > 263.1 and 445.1 > 267.1 were used to determine candesartan by using candesartan-d4 as an internal standard. After development, the method was validated according to the requirements of EMA regulatory guidelines in the concentration range 1 - 400 ng/ml in human plasma. Limit of quantification (LLOQ) was 1 ng/ml. The developed and validated method proved to be very fast and reproducible and was therefore successfully implemented in pharmacokinetic and bioequivalence studies with large number of study samples.

  13. Determination of total body water by a simple and rapid mass spectrometric method.

    Science.gov (United States)

    Van Kreel, B K; Van der Vegt, F; Meers, M; Wagenmakers, T; Westerterp, K; Coward, A

    1996-01-01

    A rapid and inexpensive method was developed to determine deuterium enrichment in body fluids. This is achieved by converting water into acetylene. To vacutainer tubes a small amount of calcium carbide is added. The tubes are evacuated and 25 microliters of sample are injected through the stopper. The reaction takes place spontaneously at room temperature in a few seconds. Enrichment at mass 27 compared with mass 26 can be determined by continuous flow isotope ratio mass spectrometry without any interference from the carrier gas helium. A series of D2O samples diluted with increasing amounts of H2O is prepared at the time of measurement of the biological samples and the measured ratios are used to calculate the isotope dilution of the unknown. The relative error of the method is 1.6% when a dose of 25 ml kg-1 is administered to the patient. The method was compared with two different methods in use in other laboratories, by a published method The means of the differences were -0.1 and 0.08 1, respectively, with standard deviations of 0.63 and 3.0.

  14. Cataclysmic Variables below the Period Gap: Mass Determinations of 14 Eclipsing Systems

    CERN Document Server

    Savoury, C D J; Dhillon, V S; Marsh, T R; Gaensicke, B T; Copperwheat, C M; Kerry, P; Hickman, R D G; Parsons, S G

    2011-01-01

    We present high-speed, three-colour photometry of the eclipsing cataclysmic variables CTCV 1300, CTCV 2354 and SDSS 1152. All three systems are below the observed "period gap" for cataclysmic variables. For each system we determine the system parameters by fitting a parameterised model to the observed eclipse light curve by chi-squared minimisation. We also present an updated analysis of all other eclipsing systems previously analysed by our group. New donor masses are generally between 1 and 2 sigma of those originally published, with the exception of SDSS 1502 and DV UMa. We note that the donor mass of SDSS 1501 has been revised upwards by 0.024Msun. This system was previously identified as having evolved passed the minimum orbital period for cataclysmic variables, but the new mass determination suggests otherwise. Our new analysis confirms that SDSS 1035 and SDSS 1433 have evolved past the period minimum for cataclysmic variables, corroborating our earlier studies. We find that the radii of donor stars are...

  15. Accurate mass analysis of N-acyl-homoserine-lactones and cognate lactone-opened compounds in bacterial isolates of Pseudomonas aeruginosa PAO1 by LC-ESI-LTQ-FTICR-MS.

    Science.gov (United States)

    Cataldi, Tommaso R I; Bianco, Giuliana; Abate, Salvatore

    2009-02-01

    N-acyl-homoserine-lactones (AHSLs) are widely conserved signal molecules present in quorum sensing systems of Gram-negative bacteria such as Pseudomonas aeruginosa. We present here the results obtained with a hybrid linear trap/Fourier transform ion cyclotron resonance (LTQ-FTICR) mass spectrometer used to investigate the occurrence of AHSLs and cognate N-acyl-homoserines (AHSs) in bacterial isolates of P. aeruginosa (strain PAO1). Two hydrolysed AHSs were found in significant amounts, most likely formed through the lactone opening of N-3-oxo-decanoyl-L-homoserine-lactone (3OC10-HSL) and N-3-oxo-dodecanoyl-L-homoserine-lactone (3OC12-HSL). Structure elucidation of these ring-opened molecules, i.e. N-3-oxo-decanoyl-L-homoserine (3OC10-HS), and N-3-oxo-dodecanoyl-L-homoserine (3OC12-HS), which are not detected by bacterial biosensors, was performed by high-resolution and accurate mass measurements upon liquid chromatography (LC) and confirmed by tandem MS in the LTQ analyser. Assignment of chemical formula, with mass spectra in the form of [M+H]+, was significantly expedited by extracted ion chromatograms (XICs) because the number of potentially plausible formulae for each protonated signalling molecule was considerably reduced a priori by the LC behaviour, the high mass measurement accuracy available in FTICR mass spectra and the isotopic patterns. At least two concentration levels were observed in spent culture supernatants of P. aeruginosa: compounds at a relatively high content (5-15 microM) that is C4-HSL, 3OC10-HS, and 3OC12-HS and those occurring at a lower content (<0.2 microM) that is C6-HSL and C8-HSL. The implications of this work extend to a great variety of Gram-negative bacteria.

  16. Direct Measurement of the Mass Difference of Ho163 and Dy163 Solves the Q-Value Puzzle for the Neutrino Mass Determination

    CERN Document Server

    Eliseev, S; Block, M; Chenmarev, S; Dorrer, H; Duellmann, Ch E; Enss, C; Filianin, P E; Gastaldo, L; Goncharov, M; Koester, U; Lautenschlaeger, F; Novikov, Yu N; Rischka, A; Schuessler, R X; Schweikhard, L; Tuerler, A

    2016-01-01

    The atomic mass difference of 163Ho and 163Dy has been directly measured with the Penning trap mass spectrometer SHIPTRAP applying the novel phase imaging ion cyclotron resonance technique. Our measurement has solved the long standing problem of large discrepancies in the Q value of the electron capture in 163Ho determined by different techniques. Our measured mass difference shifts the current Q value of 2555(16) eV evaluated in the Atomic Mass Evaluation 2012 [G. Audi et al., Chin. Phys. C 36, 1157 (2012)] by more than 7 sigma to 2833(30stat)(15sys) eV/c2. With the new mass difference it will be possible, e.g., to reach in the first phase of the ECHo experiment a statistical sensitivity to the neutrino mass below 10 eV, which will reduce its present upper limit by more than an order of magnitude.

  17. Determination of W boson mass from the four quark decay in the DELPHI experiment at LEP; Mesure de la masse du boson W dans la desintegration a quatre quarks dans l'experience DELPHI au LEP

    Energy Technology Data Exchange (ETDEWEB)

    Duperrin, Arnaud [Universite Claude Bernard, 69 - Lyon (France)

    1999-04-20

    The accurate determination of W boson mass allows testing the coherence of standard model and imposing new constrains upon some of its parameters as for instance the Higgs boson mass. The W mass obtained by direct reconstruction of WW{yields}qq-bar qq-bar, was measured by means of the data recorded in 1997 and 1998 by DELPHI experimentat the center-of-mass energies 183 GeV and 189 GeV, for a total luminosity of 212 pb{sup -1} at the LEP collider of CERN. A neural network was used to label the signal what led to an efficiency and a selection accuracy of 86% and 80%, respectively. The number of the selected events among the data was 1710. By mass reconstruction, the jet multiplicity was let to vary free between four and eight jets. A new fast algorithm of kinematic fitting of the jets was developed to improve the mass resolution of the multi-jet events, by imposing the energy and momentum conservation. The association of jets has been carried out also by means of a neural network. The W boson mass was extracted starting from a probability fitting of the two-dimensional distribution provided by complete simulation and formed by the mean and the difference of two masses of W reconstructs. A technique of Monte Carlo re-weighting has been developed to obtain the simulation spectra for arbitrary M{sub W} values. The leading systematic uncertainties are studied by gathering a large number of e{sup +}e{sup -}{yields}Z{yields}qq-bar events and by merging them for obtaining events similar to the W pairs. The value of the W mass obtained from the data based on this probability is M{sub W} = 80.350{+-}0.099 (stat.) {+-} 0.038 (exp.) {+-} 0.056 (th.) {+-} 0.018 (LEP) GeV/c{sup 2}. This result is competitive and in good agreement with other determinations. The current world average mass of W boson is M{sub W} = 80.394 {+-} 0.042 GeV/c{sup 2}. This result, included in a global fitting of the electroweak data, constraints the standard Higgs boson to a mass lower than 262 Ge

  18. Determination of albendazole sulfoxide in human plasma by using liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Saraner, Nihal; Özkan, Güler Yağmur; Güney, Berrak; Alkan, Erkin; Burul-Bozkurt, Nihan; Sağlam, Onursal; Fikirdeşici, Ezgi; Yıldırım, Mevlüt

    2016-06-01

    A rapid, simple and sensitive method was developed and validated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for determination of albendazole sulfoxide (ABZOX) in human plasma. The plasma samples were extracted by protein precipitation using albendazole sulfoxide-d3 as internal standard (IS). The chromatographic separation was performed on Waters Xbridge C18Column (100×4.6mm, 3.5μm) with a mobile phase consisting of ammonia solution, water and methanol at a flow rate of 0.70mL/min. ABZOX was detected and identified by mass spectrometry with electrospray ionization (ESI) in positive ion and multiple-reaction monitoring (MRM) mode. The method was linear in the range of 3-1500ng/mL for ABZOX. This method was successfully applied to the bioequivalence study in human plasma samples.

  19. Determination of alkyl methanesulfonates in doxazosin mesylate by gas chromatography-mass spectrometer

    Directory of Open Access Journals (Sweden)

    C Sitaram

    2011-01-01

    Full Text Available High sensitive rapid gas chromatography-mass spectrometry method for the determination of four carcinogenic alkyl methanesulfonates viz. methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate in doxazosin mesylate has been presented by using selective ion monitoring mode. The optimum separation was achieved between methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate on a DB-5 (30 m×0.32 mm×1.0 μm capillary column under programming temperature. Acetonitrile, water and ammonia (90:9:1 v/v/v mixture was used as diluent. Various factors involved in the gas chromatography-mass spectrometry method development are also presented. This method was validated as per International Conference on Harmonization guidelines. The limit of quantitation of methyl methanesulfonate, ethyl methanesulfonate, isopropyl methanesulfonate and n-butyl methanesulfonate is 6 ppm with respect to 30 mg/ml of doxazosin mesylate.

  20. Determination of the top-quark mass from hadro-production of single top-quarks

    CERN Document Server

    Alekhin, S; Thier, S

    2016-01-01

    We present a new determination of the top-quark mass $m_t$ based on the experimental data from the Tevatron and the LHC for single-top hadro-production. We use the inclusive cross sections of $s$- and $t$-channel top-quark production to extract $m_t$ and to minimize the dependence on the strong coupling constant and the gluon distribution in the proton compared to the hadro-production of top-quark pairs. As part of our analysis we compute the next-to-next-to-leading order approximation for the $s$-channel cross section in perturbative QCD based on the known soft-gluon corrections and implement it in the program Hathor for the numerical evaluation of the hadronic cross section. Results for the top-quark mass are reported in the $\\bar{MS}$ and in the on-shell renormalization scheme.

  1. Determination of the top-quark mass from hadro-production of single top-quarks

    Science.gov (United States)

    Alekhin, S.; Moch, S.; Thier, S.

    2016-12-01

    We present a new determination of the top-quark mass mt based on the experimental data from the Tevatron and the LHC for single-top hadro-production. We use the inclusive cross sections of s- and t-channel top-quark production to extract mt and to minimize the dependence on the strong coupling constant and the gluon distribution in the proton compared to the hadro-production of top-quark pairs. As part of our analysis we compute the next-to-next-to-leading order approximation for the s-channel cross section in perturbative QCD based on the known soft-gluon corrections and implement it in the program HATHOR for the numerical evaluation of the hadronic cross section. Results for the top-quark mass are reported in the MS ‾ and in the on-shell renormalization scheme.

  2. Mobile mass spectrometer for determination of heavy metals in sea water: Numerical simulation and experimental verification

    Science.gov (United States)

    Kogan, V. T.; Pavlov, A. K.; Chichagov, Yu. V.; Tubol'Tsev, Yu. V.; Savchenko, M. I.; Smirnov, O. B.; Viktorova, O. S.; Viktorov, I. V.; Vlasov, S. A.; Dubenskiĭ, B. M.; Nedvigin, V.; Gao, Ya.

    2007-12-01

    A prototype mobile mass spectrometer for direct detection of heavy metal traces in water is proposed. The instrument allows automated dosed injection of liquid samples (2.5 20.0 μl) into the lock vacuum chamber of the instrument, extraction of salts containing target components for their following introduction into the high-vacuum chamber of the instrument, and determination of the component concentrations in the initial sample by means of a portable magnetic mass spectrometer equipped with an original electron-impact ion source. Experimental testing of the spectrometer using aqueous solutions containing Zn, Fe, Cu, As, and Cd shows that the instrument can detect heavy metals in water, including salt water, at concentrations ranging from 1 mg/l to 10 μg/l. The experimental results are discussed.

  3. Determination of picomolar beryllium levels in seawater with inductively coupled plasma mass spectrometry following silica-gel preconcentration

    Energy Technology Data Exchange (ETDEWEB)

    Tazoe, Hirofumi, E-mail: tazoe@cc.hirosaki-u.ac.jp [Department of Radiation Chemistry, Institute of Radiation Emergency Mediation, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori 036-8564 (Japan); College of Humanities and Sciences, Nihon University, 3-25-40, Sakurajosui, Setagaya-ku, Tokyo 156-8550 (Japan); Yamagata, Takeyasu [College of Humanities and Sciences, Nihon University, 3-25-40, Sakurajosui, Setagaya-ku, Tokyo 156-8550 (Japan); Obata, Hajime [Atmosphere and Ocean Research Institute, The Tokyo University, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8564 (Japan); Nagai, Hisao [College of Humanities and Sciences, Nihon University, 3-25-40, Sakurajosui, Setagaya-ku, Tokyo 156-8550 (Japan)

    2014-12-10

    Highlights: • We developesd the simplest and robust SPE method for ultra low picomolar level beryllium in seawater. • Just silica gel column can quantitatively adsorb beryllium in neutral pH condition containing natural seawater. • EDTA solution can eliminate seawater matrixes retaining Be in the column, which optimize to ICP-MS detemination. • Accurate and precise Be data have been obtained for natural seawater from North Pacific Ocean. - Abstract: A robust and rapid method for the determination of natural levels of beryllium (Be) in seawater was developed to facilitate mapping Be concentrations in the ocean. A solid-phase extraction method using a silica gel column was applied for preconcentration and purification of Be in seawater prior to determination of Be concentrations with inductively coupled plasma mass spectrometry (ICP-MS). Be was quantitatively adsorbed onto silica gel from solutions with pH values ranging from 6.3 to 9, including natural seawater. The chelating agent ethylenediamine tetraacetic acid was used to remove other ions in the seawater matrix (Na, Mg, and Ca) that interfere with the ICP-MS analysis. The reproducibility of the method was 3% based on triplicate analyses of natural seawater samples, and the detection limit was 0.4 pmol kg{sup −1} for 250 mL of seawater, which is sufficient for the analysis of seawater in the open ocean. The method was then used to determine the vertical profile of Be in the eastern North Pacific Ocean, which was found to be a recycled-type profile in which the Be concentration increased with depth from the surface (7.2 pmol kg{sup −1} at <200 m) to deep water (29.2 pmol kg{sup −1} from 3500 m to the bottom)

  4. Ways for accurate analysis of high purity materials using the glow discharge mass spectrometry (GD-MS); Wege zur genauen Charakterisierung hochreiner Materialien mit der Glimmentladungs-Massenspektrometrie (GD-MS)

    Energy Technology Data Exchange (ETDEWEB)

    Gusarova, Tamara

    2010-04-14

    The main aim of this work consists in the investigation, development and application of improved possibilities of accurate analysis of high purity materials using the solid sample technique of Glow Discharge Mass Spectrometry (GD-MS), as well as in the sensitivity enhancement of GD Optical Emission Spectrometry (GD-OES) by implicating the hollow cathode effect. The emphasis of the PhD thesis consists in the accurate quantification for GD-MS. As appropriate certified reference materials (CRMs) for calibration are lacking in most cases an accurate quantification especially for trace elements mass fractions at {mu}g kg{sup -1} level can often not be achieved. To overcome this problem and to expand the possibilities of modern GD-MS hereby, synthetic standards were applied for calibration of both high resolution GD-MS instruments ''VG 9000'' and ''Element GD''. The standards were prepared by doping of matrix powder with trace element standard solutions followed by drying and pressing the doped powder to compact pellets. With the quantification approach worked out and described here accurate analysis results with small uncertainties can be achieved for most elements of periodic table in almost every matrix composition. Furthermore direct traceability of the analytical results to the International System of Units (SI) is provided ensuring their higher metrological quality. Numerous additional systematic investigations concerning the preparation of the synthetic standards and their properties were carried out. The results of calibration of GD-MS instruments with synthetic standards for Co (Co-C), Cu, In, Fe and Zn matrices were checked by measuring CRMs. These results were also contrasted with those of other quantification approaches, as usually used in GD-MS routine. The results achieved with synthetic standards had the highest accuracy. The successful participation in the round robin test CCQM-P107 between international

  5. Determining the topology of virus assembly intermediates using ion mobility spectrometry-mass spectrometry.

    Science.gov (United States)

    Knapman, Tom W; Morton, Victoria L; Stonehouse, Nicola J; Stockley, Peter G; Ashcroft, Alison E

    2010-10-30

    We have combined ion mobility spectrometry-mass spectrometry with tandem mass spectrometry to characterise large, non-covalently bound macromolecular complexes in terms of mass, shape (cross-sectional area) and stability (dissociation) in a single experiment. The results indicate that the quaternary architecture of a complex influences its residual shape following removal of a single subunit by collision-induced dissociation tandem mass spectrometry. Complexes whose subunits are bound to several neighbouring subunits to create a ring-like three-dimensional (3D) architecture undergo significant collapse upon dissociation. In contrast, subunits which have only a single neighbouring subunit within a complex retain much of their original shape upon complex dissociation. Specifically, we have determined the architecture of two transient, on-pathway intermediates observed during in vitro viral capsid assembly. Knowledge of the mass, stoichiometry and cross-sectional area of each viral assembly intermediate allowed us to model a range of potential structures based on the known X-ray structure of the coat protein building blocks. Comparing the cross-sectional areas of these potential architectures before and after dissociation provided tangible evidence for the assignment of the topologies of the complexes, which have been found to encompass both the 3-fold and the 5-fold symmetry axes of the final icosahedral viral shell. Such insights provide unique information about virus assembly pathways that could allow the design of anti-viral therapeutics directed at the assembly step. This methodology can be readily applied to the structural characterisation of many other non-covalently bound macromolecular complexes and their assembly pathways.

  6. Simultaneous determination of five anti-epilepsy drugs in human plasma using liquid chromatography-mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    STEFANIE; WeiBig

    2010-01-01

    A new liquid chromatography-mass spectrometry method for the determination of carbamazepine,clonazepam,alprazolam,estazolam and phenytoin in human plasma has been developed by using diazepam as an internal standard.Chromatographic separation was performed on a Zorbax SB-C18 column(30 mm × 2.1 mm,3.5 ?m) with a mobile phase consisting of methanol and aqueous 25 mM ammonium acetate using gradient elution.A diethyl ether extraction method was used for the extraction of five anti-epilepsy drugs.The final extract was injected for analysis by LC-MS/MS.The method was validated within the concentration range of 50-5000 ng mL-1 for five anti-epilepsy drugs.The precision of the assay(RSD%) was less than 10% at all concentration levels within the tested range.The method recoveries for all samples were more than 90%.The results indicate that the method is specific,sensitive and accurate,and suitable to study the pharmacokinetics,to adjust the dosage for individual administration,and to monitor the drug-concentration and drug abuse of the five anti-epilepsy drugs.

  7. Determination of tin isotope ratios in cassiterite by femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Schulze, Marie; Ziegerick, Marco; Horn, Ingo; Weyer, Stefan; Vogt, Carla

    2017-04-01

    In comparison to isotope analysis of dissolved samples femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry (fs-LA-MC-ICP-MS) enables precise isotope ratio analyses consuming much less sample material and with a minimum effort in sample preparation. This is especially important for the investigation of valuable historical objects for which visual traces of sampling are unwanted. The present study provides a basis for tin isotope ratio measurements using LA-MC-ICP-MS technique. For this, in house isotope standards had to be defined. Investigations on interferences and matrix effects illustrate that beside Sb only high Te contents (with values above those to be expected in cassiterite) result in a significant shift of the measured tin isotope ratios. This effect can partly be corrected for using natural isotope abundances. However, a natural isotope fractionation of Te cannot be excluded. Tin beads reduced from cassiterite were analysed by laser ablation and after dissolution. It was shown that tin isotope ratios can be determined accurately by using fs-LA-MC-ICP-MS. Furthermore the homogeneity of tin isotope ratios in cassiterite was proven.

  8. [Determination of glufosinate residue in tea by liquid chromatography-tandem mass spectrometry coupled with precolumn derivatization].

    Science.gov (United States)

    Lin, Yonghui; Liu, Zhengcai; Yang, Fang; Qiu, Yuanjin; Liu, Suzhen; Su, Zhijiao; Zhang, Qiong; Xue, Zhimin; Fang, Yu

    2012-12-01

    A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established for the determination of glufosinate (GLUF) residue in tea. The GLUF was extracted with water for 30 min under ultrasonication, and cleaned-up using a C18 solid phase extraction cartridge, then derived using fluorenylmethylchloroformate (FMOC-Cl) in borate buffer for 2 h. The separation was performed on a Kinetex C18 column with the mobile phases of acetonitrile and 5 mmol/L ammonium acetate aqueous solution (containing 0.2% (v/v) formic acid) in a gradient elution mode. The identification and quantification of the GLUF were carried out by MS/MS in negative electrospray ionization (ESI(-)) and multiple reaction monitoring (MRM) mode, the quantification analysis was performed by external standard method. The calibration curve showed good linearity in the range of 2.5 - 50.0 microg/L with the correlation coefficient r2 > 0.999. The limit of quantification (LOQ) was 0.10 mg/kg. The average recoveries of GLUF spiked at 0.10, 0.50 and 1.00 mg/kg levels in tea were between 61.6% and 81.4%, and the relative standard deviations (RSDs) were between 3.2% and 8.4%. The method is simple, rapid, sensitive, accurate and suitable for the confirmation and quantification of GLUF in tea.

  9. [Determination of apomorphine, sildenafil and alprostadil in medicines for erectile dysfunction by high performance liquid chromatography-mass spectrometry].

    Science.gov (United States)

    Xu, Yuanjin; Xu, Guiping

    2005-11-01

    A high performance liquid chromatography-mass spectrometry (LC-MS) analytical method for illicit drugs, apomorphine, sildenafil and alprostadil, in medicines for erectile dysfunction has been developed. The samples were extracted with methanol using ultrasound-assisted extraction. The chromatographic separation was performed on a Zorbax Eclipse XDB-C18 column using acetonitrile-0.5% formic acid aqueous solution as mobile phase. The three compounds were identified by retention time and m/z and quantified by peak area. The results demonstrated that the linear ranges were 50.0 - 5 000.0 microg/L, 10.0 - 1 000.0 microg/L, 40.0 - 4 000.0 microg/L, with detection limits of 20.0, 4.0, 10.0 microg/L for apomorphine, sildenafil and alprostadil, respectively. The average recoveries and the relative standard deviations were 89% - 95% and 9.5% - 11%. The method is simple, rapid, accurate and suitable for the simultaneous determination of these drugs in medicines for erectile dysfunction.

  10. Method for (236)U Determination in Seawater Using Flow Injection Extraction Chromatography and Accelerator Mass Spectrometry.

    Science.gov (United States)

    Qiao, Jixin; Hou, Xiaolin; Steier, Peter; Nielsen, Sven; Golser, Robin

    2015-07-21

    An automated analytical method implemented in a flow injection (FI) system was developed for rapid determination of (236)U in 10 L seawater samples. (238)U was used as a chemical yield tracer for the whole procedure, in which extraction chromatography (UTEVA) was exploited to purify uranium, after an effective iron hydroxide coprecipitation. Accelerator mass spectrometry (AMS) was applied for quantifying the (236)U/(238)U ratio, and inductively coupled plasma mass spectrometry (ICPMS) was used to determine the absolute concentration of (238)U; thus, the concentration of (236)U can be calculated. The key experimental parameters affecting the analytical effectiveness were investigated and optimized in order to achieve high chemical yields and simple and rapid analysis as well as low procedure background. Besides, the operational conditions for the target preparation prior to the AMS measurement were optimized, on the basis of studying the coprecipitation behavior of uranium with iron hydroxide. The analytical results indicate that the developed method is simple and robust, providing satisfactory chemical yields (80-100%) and high analysis speed (4 h/sample), which could be an appealing alternative to conventional manual methods for (236)U determination in its tracer application.

  11. Determination of iodine in oyster tissue by isotope dilution laser resonance ionization mass spectrometry.

    Science.gov (United States)

    Fassett, J D; Murphy, T J

    1990-02-15

    The technique of laser resonance ionization mass spectrometry has been combined with isotope dilution analysis to determine iodine in oyster tissue. The long-lived radioisotope, 129I, was used to spike the samples. Samples were equilibrated with the 129I, wet ashed under controlled conditions, and iodine separated by coprecipitation with silver chloride. The analyte was dried as silver ammonium iodide upon a tantalum filament from which iodine was thermally desorbed in the resonance ionization mass spectrometry instrument. A single-color, two-photon resonant plus one-photon ionization scheme was used to form positive iodine ions. Long-lived iodine signals were achieved from 100 ng of iodine. The precision of 127I/129I measurement has been evaluated by replicate determinations of the spike, the spike calibration samples, and the oyster tissue samples and was 1.0%. Measurement precision among samples was 1.9% for the spike calibration and 1.4% for the oyster tissue. The concentration of iodine determined in SRM 1566a, Oyster Tissue, was 4.44 micrograms/g with an estimate of the overall uncertainty for the analysis of +/- 0.12 microgram/g.

  12. Hydrophilic interaction liquid chromatography coupled to high-resolution mass spectrometry to determine artificial sweeteners in environmental waters.

    Science.gov (United States)

    Salas, Daniela; Borrull, Francesc; Fontanals, Núria; Marcé, Rosa Maria

    2015-06-01

    Artificial sweeteners are food additives employed as sugar substitutes which are now considered to be emerging organic contaminants. In the present study, a method is developed for the determination of a group of artificial sweeteners in environmental waters. Considering the polar and hydrophilic character of these compounds, hydrophilic interaction liquid chromatography is proposed for their separation as an alternative to traditional reversed-phase liquid chromatography. Two stationary phases with different chemistry were compared for this purpose. For the detection of the analytes, high-resolution mass spectrometry (Orbitrap) was employed to take advantage of its benefits in terms of reliable quantification and confirmation for the measurement of accurate masses. Solid-phase extraction was chosen as the sample treatment, in which the extract in a mixture of NH4OH:MeOH:ACN (1:4:15) was directly injected into the chromatographic system, simplifying the analytical procedure. The optimized method was validated on river and waste water samples. For example, in the case of effluent water samples, limits of detection ranged from 0.002 to 0.7 μg/L and limits of quantification ranged from 0.004 to 1.5 μg/L. Apparent (whole method) recoveries ranged from 57 to 74% with intra-day precision (%RSD, n = 5) ranging from 6 to 25%. The method was successfully applied to water samples from different rivers in Catalonia and different waste water treatment plants in Tarragona. Acesulfame, cyclamate, saccharine and sucralose were found in several samples.

  13. [Determination of the distribution of relative molecular mass of organic matter by high pressure size exclusion chromatography with UV and TOC detectors].

    Science.gov (United States)

    Zhang, Han; Dong, Bing-Zhi

    2012-09-01

    An on-line high pressure size exclusion chromatography (HPSEC) with UV and TOC detectors was adapted to examine the distribution of relative molecular mass of natural organic matter (NOM). Through synchronous determination of UV254 and TOC responses in a wide range of relative molecular mass, it was possible to accurately characterize the structure of NOM, especially for some non-aromatic and non-conjugated double bond organics which have low response to UV. It was found that, TOC detector was capable of detecting all kinds of organic matters, including sucrose, sodium alginate and other hydrophilic organic compounds. The sample volume had a positively linear correlation with the TOC response, indicating that the larger volume would produce stronger responses. The effect of ion strength was relatively low, shown by the small decrease of peak area (1.2% ) from none to 0.2 mol x L(-1) NaCl. The pH value of tested samples should be adjusted to neutral or acidic because when the samples were alkaline, the results might be inaccurate. Compared to the sample solvents adopted as ultrapure water, the samples prepared by mobile phase solvents had less interference to salt boundary peak. The on-line HPSEC-UV-TOC can be used accurately to characterize the distribution of relative molecular mass and its four fractions in River Xiang.

  14. Determination of protein-ligand interactions using accelerator mass spectrometry: modified crosslinking assay.

    Science.gov (United States)

    Hah, Sang Soo

    2009-05-01

    A highly sensitive detection method for the determination of protein-ligand interactions has been developed. Radiocarbon-labeled 17beta-estradiol was incubated with estrogen receptor-alpha; as a selective binding partner, and covalently attached using crosslinking agents, to form covalently linked protein-ligand complexes. After separation using a denaturing gel, the (14)C content in the sliced gels was identified by accelerator mass spectrometry. The obtained data demonstrated specific binding of the small molecule to its binding partner. In theory, this method can be applied to most protein-ligand interaction studies.

  15. Heat-And-Mass Transfer Relationship to Determine Shear Stress in Tubular Membrane Systems

    DEFF Research Database (Denmark)

    Ratkovich, Nicolas Rios; Nopens, Ingmar

    2012-01-01

    The main drawback of Membrane Bioreactors (MBRs) is the fouling of the membrane. One way to reduce this fouling is through controlling the hydrodynamics of the two-phase slug flow near the membrane surface. It has been proven in literature that the slug flow pattern has a higher scouring effect...... measurements are required. Therefore, this work proposes an alternative method that uses already existing heat transfer relationships for two phase flow and links them through a dimensionless number to the mass transfer coefficient (Sherwood number) to obtain an empirical relationship which can be used...... to determine the shear stress....

  16. Determination of ketone bodies in blood by headspace gas chromatography-mass spectrometry

    DEFF Research Database (Denmark)

    Holm, Karen Marie Dollerup; Linnet, Kristian; Rasmussen, Brian Schou

    2010-01-01

    A gas chromatography-mass spectrometry (GC-MS) method for determination of ketone bodies (ß-hydroxybutyrate, acetone, and acetoacetate) in blood is presented. The method is based on enzymatic oxidation of D-ß-hydroxybutyrate to acetoacetate, followed by decarboxylation to acetone, which...... was quantified by the use of headspace GC-MS using acetone-(13)C(3) as an internal standard. The developed method was found to have intra- and total interday relative standard deviations acetone+acetoacetate levels (~25 to 8300 µM) and D-ß-hydroxybutyrate levels (~30 to 16500 µM). Recovery values varied...

  17. Determination of the Electron Neutrino Mass from Experiments on Electron-Capture Beta-Decay (EC)

    CERN Multimedia

    2002-01-01

    The aim of the programme is to measure the electron-neutrino mass, for which at present an upper limit of 500~eV is known. \\\\ \\\\ The experiment studies the shape of the internal bremsstrahlung spectrum in electron-capture near its upper end-point and deduces a mass from small shape changes completely analogous to those in the well-known determination of the electron antineutrino mass in the tritium beta-minus decay. \\\\ \\\\ In a low-energy bremsstrahlung process, the capture takes place from a virtual S state associated with a radiative P~@A~S electromagnetic transition, and the resonant nature of the process leads to important enhancements of the photon intensities at low energy, in particular near the resonance energies co (X-rays). This effect gives this type of experiment a chance to compete with experiments on continuous beta spectra. \\\\ \\\\ The programme concentrates on two long-lived isotopes: \\\\ \\\\ 1)~~|1|6|3Ho. The Q value for this isotope has been found to be 2.6-2.7 keV. A detector specially construct...

  18. A new determination of the mass of the eta meson at COSY-ANKE

    CERN Document Server

    Goslawski, P; Barsov, S; Burmeister, I; Chiladze, D; Dymov, S; Gebel, R; Hartmann, M; Kacharava, A; Kulessa, P; Lehrach, A; Lorentz, B; Maier, R; Mersmann, T; Mielke, M; Mikirtychiants, S; Ohm, H; Papenbrock, M; Prasuhn, D; Rausmann, T; Serdyuk, V; Stockhorst, H; Stroeher, H; Taeschner, A; Valdau, Y; Wilkin, C

    2012-01-01

    A value for the mass of the $\\eta$ meson has been obtained at the COSY-ANKE facility on the basis of pure kinematics through the measurement of a set of deuteron laboratory beam momenta and associated $^3$He center-of-mass momenta in the $dp\\to{}^{3}$He$\\,X$ reaction. The $\\eta$ was then identified by the missing-mass peak and the production threshold determined. The individual beam momenta were fixed with a relative precision of $3 \\times 10^{-5}$ for values around 3 GeV/c by using a polarized deuteron beam and inducing an artificial depolarizing spin resonance, which occurs at a well-defined frequency. The final-state momenta in the two-body $dp\\to{}^{3}$He$\\,\\eta$ reaction were investigated in detail by studying the size of the $^3$He momentum ellipse with the forward detection system of the ANKE spectrometer. Taking advantage of the full geometrical acceptance, the necessary fine calibration of the spectrometer for this high precision experiment was achieved through a comprehensive study of the $^3$He fin...

  19. Determination of the critical molar mass of ovalbumin oligomers degraded by ultrasound

    Directory of Open Access Journals (Sweden)

    BRATOLJUB H. MILOSAVLJEVIC

    2000-02-01

    Full Text Available An experimental method has been developed which enables the determination of the critical molar mass (Mmc of ovalbumin oligomers degraded by ultrasound of known frequency. To test the validity of the Mmc postulate, a series of ovalbumin oligomers was prepared by the radiolytic cross-linking of 1% solutions of ovalbumin monomer dissolved in 50 mM Na/K-phosphate buffer pH 7.0 saturated with N2O. Under these conditions, irradiation with 5 kGy from a 60Co source, yielded ovalbumin dimers, trimers, tetramers, and higher order oligomers. On the basis of the results obtained with the ovalbumin oligomers, it was concluded that for ultrasound of 23 kHz frequency and 5mm amplitude, the Mmc was 274000 + 14000 g/mol. Our results confirmed that the two postulates in the chemistry of polymer degradation by ultrasound are valid when ovalbumin oligomers are used as substrates, i.e., (1 that the higher the molar mass of the original macromolecule, the faster is its degradation rate, and (2 that a lower molar mass limit (LMmL exists below which the macromolecules are resistent to further degradation.

  20. Determination of aerosol extinction coefficient and mass extinction efficiency by DOAS with a flashlight source

    Institute of Scientific and Technical Information of China (English)

    Si Fu-Qi; Liu Jian-Guo; Xie Pin-Hua; Zhang Yu-Jun; Liu Wen-Qing; Hiroaki Kuze; Liu Cheng; Nofel Lagrosas; Nobuo Takeuchi

    2005-01-01

    With the method of differential optical absorption spectroscopy (DOAS), average concentrations of aerosol particles along light path were measured with a flashlight source in Chiba area during the period of one month. The optical thickness at 550 nm is compared with the concentration of ground-measured suspended particulate matter (SPM). Good correlations are found between the DOAS and SPM data, leading to the determination of the aerosol mass extinction efficiency (MEE) to be possible in the lower troposphere. The average MEE value is about 7.6m2.g-1, and the parameter exhibits a good correlation with the particle size as determined from the wavelength dependence of the DOAS signal intensity.

  1. Simultaneous determination of amphetamines and ketamines in urine by gas chromatography/mass spectrometry.

    Science.gov (United States)

    Lin, Huei Ru; Lua, Ahai Chang

    2006-01-01

    A method for the simultaneous determination of amphetamines and ketamines (ketamine, norketamine and dehydronorketamine) in urine samples by gas chromatography/mass spectrometry was developed and validated. Urine samples were extracted with organic solvent and derivatized with trifluoroacetic anhydride (TFAA). The limits of detection and limits of quantification for each analyte were lower than 19 and 30 ng/mL, respectively. Within-day and between-day precisions were within 0.5% and 10.6%, respectively. Biases for three levels of control samples were within -10.6% and +7.8%. The concentration of dehydronorketamine was greater than those of ketamine or norketamine in 19 of 35 ketamine-positive samples. A group of 110 human urine samples previously determined to contain at least one of the target analytes was analyzed using the new method, and excellent agreement was observed with previous results.

  2. Experimental determination of isotope enrichment factors – bias from mass removal by repetitive sampling

    DEFF Research Database (Denmark)

    Buchner, Daniel; Jin, Biao; Ebert, Karin

    2017-01-01

    Application of compound-specific stable isotope approaches often involves comparisons of isotope enrichment factors (ε). Experimental determination of ε-values is based on the Rayleigh equation, which relates the change in measured isotope ratios to the decreasing substrate fractions and is valid...... to account for mass removal and for volatilization into the headspace. In this study we use both synthetic and experimental data to demonstrate that the determination of ε-values according to current correction methods is prone to considerable systematic errors even in well-designed experimental setups....... In response, we present novel, adequate methods to eliminate systematic errors in data evaluation. A model-based sensitivity analysis serves to reveal the most crucial experimental parameters and can be used for future experimental design to obtain correct ε-values allowing mechanistic interpretations....

  3. Determination of Mass Spectrometric Sensitivity of Different Metalloporphyrin Esters Relative to Porphyrin Ester

    DEFF Research Database (Denmark)

    Larsen, Elfinn; Egsgaard, Helge; Møller, J.

    1977-01-01

    Quantitative determination of metalloporphyrin contamination in preparations of biologically important porphyrins was achieved mass spectrometrically by application of the integrated ion current technique. For this purpose, the relative molecular ion sensitivities of the contaminating metal compl...... complexes were determined from the ratios of the integrated molecular ion currents of a series of calibration samples containing a porphyrin ester and one of its metal complexes in known molar ratio. Complexes formed with divalent ions of Cu, Zn, Fe, Co and Ni of copro- as well as uro......-prophyrin permethylester were all found to have the same molecular ion sensitivities as their metal-free porphyrin ester. The relative metalloporphyrin ester content in a sample of porphyrin ester was thus obtained directly as the integrated ion current ratios of the normalized molecular ions. The preparation...

  4. Fast mass spectrometry-based enantiomeric excess determination of proteinogenic amino acids.

    Science.gov (United States)

    Fleischer, Heidi; Thurow, Kerstin

    2013-03-01

    A rapid determination of the enantiomeric excess of proteinogenic amino acids is of great importance in various fields of chemical and biologic research and industries. Owing to their different biologic effects, enantiomers are interesting research subjects in drug development for the design of new and more efficient pharmaceuticals. Usually, the enantiomeric composition of amino acids is determined by conventional analytical methods such as liquid or gas chromatography or capillary electrophoresis. These analytical techniques do not fulfill the requirements of high-throughput screening due to their relative long analysis times. The method presented allows a fast analysis of chiral amino acids without previous time consuming chromatographic separation. The analytical measurements base on parallel kinetic resolution with pseudoenantiomeric mass tagged auxiliaries and were carried out by mass spectrometry with electrospray ionization. All 19 chiral proteinogenic amino acids were tested and Pro, Ser, Trp, His, and Glu were selected as model substrates for verification measurements. The enantiomeric excesses of amino acids with non-polar and aliphatic side chains as well as Trp and Phe (aromatic side chains) were determined with maximum deviations of the expected value less than or equal to 10ee%. Ser, Cys, His, Glu, and Asp were determined with deviations lower or equal to 14ee% and the enantiomeric excess of Tyr were calculated with 17ee% deviation. The total screening process is fully automated from the sample pretreatment to the data processing. The method presented enables fast measurement times about 1.38 min per sample and is applicable in the scope of high-throughput screenings.

  5. Liquid chromatography-mass spectrometric and liquid chromatography-tandem mass spectrometric determination of hallucinogenic indoles psilocin and psilocybin in "magic mushroom" samples.

    Science.gov (United States)

    Kamata, Tooru; Nishikawa, Mayumi; Katagi, Munehiro; Tsuchihashi, Hitoshi

    2005-03-01

    Accurate and sensitive analytical methods for psilocin (PC) and psilocybin (PB), tryptamine-type hallucinogens contained in "magic mushrooms," were investigated using liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The chromatographic separation on an ODS column and mass spectral information gave complete discrimination between PC and PB without derivatization. The mass spectrometric detection had a high sensitivity, and the tandem mass spectrometric detection provided more specificity and accuracy, as well as high sensitivity. The detection limits ranged from 1 to 25 pg by LC-MS in the selected ion monitoring mode, and the intra- and inter-day coefficients of variation were estimated to be 4.21-5.93% by LC-MS-MS in the selected reaction monitoring mode. By applying the present LC-MS-MS technique to four real samples, the contents of PC and PB were found to vary over a wide range (0.60-1.4 and 0.18-3.8 mg/g dry wt. for PC and PB, respectively) between samples.

  6. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. Dron

    2010-04-01

    Full Text Available The functional group composition of various organic aerosols (OA is being investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCI-MS/MS. The determinations of the three functional groups' contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups and precursor ion (nitro groups scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA produced through photo-oxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounted for 1.7% (vehicular to 13.5% (o-xylene photo-oxidation of the organic carbon. The diagnostic functional group ratios are then used to tentatively differentiate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France during a strong winter pollution event. The three functional groups under study account for a total functionalisation rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to distinguish the sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assesses a wood burning organic carbon contribution of about 60%. Finally, examples of functional group mass

  7. Selenosugar determination in porcine liver using multidimensional HPLC with atomic and molecular mass spectrometry.

    Science.gov (United States)

    Lu, Ying; Pergantis, Spiros A

    2009-01-01

    A methodology based on liquid chromatography coupled online with atomic and molecular mass spectrometry was developed for identifying trace amounts of the selenosugar methyl 2-acetamido-2-deoxy-1-seleno-β-D-galactopyranoside (SeGalNAc) in porcine liver, obtained from an animal that had not received selenium supplementation. Sample preparation was especially critical for the identification of SeGalNAc by molecular mass spectrometry. This involved liver extraction using a Tris buffer, followed by sequential centrifugations. The resulting cytosolic fraction was pre-concentrated and the low molecular weight selenium (LMWSe) fraction obtained from a size exclusion column was collected, concentrated, and subsequently analyzed using a tandem dual-column HPLC-ICP-MS system which consisted of strong cation exchange (SCX) and reversed phase (RP) columns coupled in tandem. Hepatocytosolic SeGalNAc was tentatively identified by retention time matching and spiking. Its identity was further confirmed by using the same type of chromatography on-line with atmospheric pressure chemical ionization tandem mass spectrometry operated in the selected reaction monitoring (SRM) mode. Four SRM transitions, characteristic of SeGalNAc, were monitored and their intensity ratios determined in order to confirm SeGalNAc identification. Instrument limits of detection for SeGalNAc by SCX-RP HPLC-ICP-MS and SCX-RP HPLC-APCI-MS/MS were 3.4 and 2.9 μg Se L(-1), respectively. Selenium mass balance analysis revealed that trace amounts of SeGalNAc, 2.16±0.94 μg Se kg(-1) liver (wet weight) were present in the liver cytosol, corresponding to 0.4% of the total Se content in the porcine liver.

  8. Effect of atmospheric flux uncertainties on the determination of the neutrino mass hierarchy

    Directory of Open Access Journals (Sweden)

    Sandroos Joakim

    2016-01-01

    Full Text Available The next generation of large-volume neutrino telescopes will include low-energy subarrays which will be able to measure neutrinos with energies of a few GeV. In this energy range the primary signal below the horizon is neutrinos created by cosmic ray interactions in the atmosphere. The measured event rate will depend on the neutrino mass hierarchy, allowing determination of this quantity to a significance level of about 3.5 sigma within a 5-year period, mostly limited by systematic uncertainties. We present here the impact of the uncertainties on the atmospheric neutrino flux normalization on the determination of the neutrino mass hierarchy. We suggest constraining the systematic uncertainties by including the downgoing neutrino sample, which will increase the significance. This work was performed using simulation data from the low-energy extension to the IceCube detector located at the geographic south pole, PINGU, and is relevant to a wide range of other experiments.

  9. Determination of doxepin and desmethyldoxepin in human plasma using liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Badenhorst, D; Sutherland, F C; de Jager, A D; Scanes, T; Hundt, H K; Swart, K J; Hundt, A F

    2000-05-26

    A sensitive method for the simultaneous determination of doxepin and its active metabolite desmethyldoxepin in plasma was established, using high-performance liquid chromatographic separation with tandem mass spectrometric detection. The samples were extracted with hexane-isoamyl alcohol, separated on a Phenomenex Luna C18 5 microm, 150x2.1 mm column with a mobile phase consisting of methanol-water-formic acid (600:400:0.5, v/v) at a flow-rate of 0.25 ml/min. Detection was achieved by a Perkin-Elmer API 2000 mass spectrometer at unit resolution in multiple reaction monitoring mode monitoring the transition of the protonated molecular ions m/z 280.2, 266.2 and 250.1 to the product ions m/z 107.1, 107.1 and 191.0 for analyte, metabolite and internal standard (benzoctamine-HCl), respectively. TurbolonSpray ionisation was used for ion production. The mean recovery for doxepin and desmethyldoxepin was 90% and 75%, respectively, with a lower limit of quantification at 0.320 ng/ml and 0.178 ng/ml for the analyte and its metabolite, respectively, using 0.5 ml plasma for extraction. This is the first assay method described for the simultaneous determination of doxepin and desmethyldoxepin in plasma using LC-MS-MS. The method is sensitive enough to be used in drug bioavailability studies with doxepin.

  10. A Method for Black Hole Mass Determination in Accretion Powered X-Ray Sources

    CERN Document Server

    Shrader, C R; Shrader, Chris; Titarchuk, Lev

    2003-01-01

    We describe a method for the determination of black-hole masses based on information inferred from high-energy spectra. It is required that the spectral energy distribution consist of thermal and Comptonized components. One can then, in principle, infer the depth of the gravitational potential well for sources of known distance. The thermal component is inferred by the integration of a blackbody spectral form over the disk. We assume that the color temperature distribution in the disk has a specific shape given by the Shakura-Sunyaev (1973) disk model which goes to zero at the inner disk radius and at infinity and has a maximum at 4.2 Schwarzchild radii. In this formulation there is only one parameter, the so called color correction factor, relating the apparent temperature to effective temperature which characterizes the thermal emission component. We have made use of improved Galactic black hole binary dynamical mass determinations to derive, in effect, an empirical calibration of this factor. We then prese...

  11. [Determination of acrylamide in fried starchy foods by gas chromatography-mass spectrometry].

    Science.gov (United States)

    Zhong, Weike; Chen, Dongdong; Yong, Wei; Liu, Zhiming; Qiu, Yueming; Tang, Yingzhang

    2005-05-01

    A method was developed for the determination of acrylamide in fried starchy foods using isotope dilution gas chromatograpy-selected mass spectrometry (GC-MS). The acrylamide was extracted from samples by water, then centrifuged and cleaned up by a column of graphitized carbon black. Acrylamide was derivatized through bromination at low pH and low temperature and determined by GC-MS. With the aid of the 13C-substituted acrylamide internal standard, the mass spectrum in GC-MS was interpreted, and the content of acrylamide was measured. The limit of quantitative detection (S/N > 10) was 5 microg/kg and the recovery was in the range of 90%-105% and relative standard deviation is 6.3%. The levels of acrylamide in some fried foodstuffs such as French fries was surveyed using the method. French fries were found to contain 278-4518 microg/kg acrylamide. It means that the content of acrylamide in French fries is 10,000 times higher than the drinking water guideline of World Health Organization for acrylamide.

  12. Determination of bromate in drinking water by ultraperformance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Alsohaimi, Ibrahim Hotan; Alothman, Zeid Abdullah; Khan, Mohammad Rizwan; Abdalla, Mohammad Abulhassan; Busquets, Rosa; Alomary, Ahmad Khodran

    2012-10-01

    Bromate is a byproduct formed as a result of disinfection of bromide-containing source water with ozone or hypochlorite. The International Agency for Research on Cancer has recognized bromate as a possible human carcinogen, thus it is essential to determine in drinking water. Present work highlights a development of sensitive and fast analytical method for bromate determination in drinking water by using ultraperformance liquid chromatography-tandem mass spectrometry. The quality parameters of the developed method were established, obtaining very low limit of detection (0.01 ng/mL), repeatability and reproducibility have been found to be less than 3% in terms of relative standard deviation when analyzing a bromate standard at 0.05 μg/mL with 0.4 min analysis time. Developed method was applied for the analysis of metropolitan and bottled water from Saudi Arabia; 22 samples have been analyzed. Bromate was detected in the metropolitan water samples (from desalinization source) at concentrations ranging between 3.43 and 75.04 ng/mL and in the bottled water samples at concentrations ranging between 2.07 and 21.90 ng/mL. Moreover, in comparison to established analytical methods such as liquid chromatography-tandem mass spectrometry, the proposed method was found to be very sensitive, selective and rapid for the routine analysis of bromate at low level in drinking water.

  13. [Determination of glyphosate and aminomethylphosphonic acid in rice using liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Cao, Zhaoyun; Mou, Renxiang; Chen, Mingxue

    2010-08-01

    A method was developed for the determination of glyphosate (GLY) and aminomethylphosphonic acid (AMPA) in rice using liquid chromatography tandem mass spectrometry (LC-MS/MS). The sample was extracted with water followed by a simple cleanup with a C18 solid phase extraction (SPE) cartridge, and then GLY and AMPA were derivatized using 9-fluorenylmethoxycarbonyl (FMOC-Cl) in borate buffer. The derivatives of GLY and AMPA were separated on a C18 column with gradient elution with the mobile phase of acetonitrile and 5 mmol/L ammonium acetate (pH 9), and finally detected with negative ion electrospray ionization-mass spectrometry (ESI-MS) in multiple reaction monitoring (MRM) mode. The results showed that the linearities of GLY and AMPA were in the concentration range of 0.000 50 to 1.0 mg/L with the correlation coefficients of 0.999 7 and 0.999 9, respectively. The mean spiked recoveries of GLY and AMPA at 3 spiked levels ranged from 72.5% to 113.6% with the relative standard deviations (RSD, n = 5) of 3.8% - 16.2%. The limits of detection were 2.0 and 3.0 microg/kg for GLY and AMPA, respectively. This method is rapid, sensitive, and suitable for simultaneous determination of GLY and AMPA in rice.

  14. [Simultaneous determination of ethyl carbamate and chloropropanols in flavorings by gas chromatography-triple quadrupole tandem mass spectrometry].

    Science.gov (United States)

    Xu, Xiaomin; He, Huali; Ruan, Yudi; Huang, Baifen; Zhang, Jingshun; Cai, Zengxuan; Ren, Yiping

    2013-11-01

    A simultaneous determination method for ethyl carbamate (EC) and chloropropanols (3-monochloropropane-1, 2-diol (3-MCPD) and 2-monochloropropane-1, 3-diol (2-MCPD)) in flavorings was developed by gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS). After spiked with internal standard, the sample was extracted by matrix solid-phase dispersion extraction technique with an Extrelut NT column. Hexane was used to wash the fat soluble matrix interferences and then an ethyl acetate-ethyl ether (20: 80, v/v) mixture was added to elute the analytes. The concentrated extract was detected by GC-MS/MS in multiple reaction monitoring (MRM) mode. The limits of detection (LODs) were 2, 5 and 5 microg/kg for EC, 3-MCPD and 2-MCPD, respectively. The linear ranges were 5 - 1 000 microg/kg (r = 0.9997), 10-1000 microg/kg (r = 0.999 1) and 10-1000 microg/kg (r = 0.999 5) for EC, 3-MCPD and 2-MCPD, respectively. In soy sauce, yellow rice wine, salami sauce and flavoring of instant noodle matrices, the recoveries (RSDs, n = 7) in MRM mode at the levels of 20, 100 and 400 microg/kg were 87.7%-104% (4.3%-10.7%), 90.1%-109% (2.6%-10.2%), and 90.9%-103% (3.0%-9.5%), respectively. EC, 3-MCPD and 2-MCPD were found in some real samples of the soy sauce, wine and flavoring of instant noodle. EC or 3-MCPD was found in some of the salami samples. The method is accurate, fast and suitable for the simultaneous determination of EC, 3-MCPD and 2-MCPD in flavorings.

  15. Determination of alkyl amines in atmospheric aerosol particles: a comparison of gas chromatography-mass spectrometry and ion chromatography approaches

    Directory of Open Access Journals (Sweden)

    R.-J. Huang

    2014-03-01

    Full Text Available In recent years low molecular weight alkyl amines have been recognized to play an important role in particle formation and growth in the lower atmosphere. However, major uncertainties are associated with their atmospheric processes, sources and sinks, mostly due to the lack of ambient measurements and the difficulties in accurate quantification of alkyl amines at trace level. In this study, we present the evaluation and optimization of two analytical approaches, i.e., gas chromatography-mass spectrometry (GC-MS and ion chromatography (IC, for the determination of alkyl amines in aerosol particles. Alkyl amines were converted to carbamates through derivatization with isobutyl chloroformate for GC-MS determination. A set of parameters affecting the analytical performances of the GC-MS approach, including reagent amount, reaction time and pH value, was evaluated and optimized. The accuracy is 84.3–99.1%, and the limits of detection obtained are 1.8–3.9 pg. For the IC approach, a solid phase extraction (SPE column was used to separate alkyl amines from interfering cations before IC analysis. 1–2% (v/v of acetone (or 2–4% (v/v of acetonitrile was added to the eluent to improve the separation of alkyl amines on the IC column. The limits of detection obtained are 2.1–15.9 ng and the accuracy is 55.1–103.4%. The lower accuracy can be attributed to evaporation losses of amines during the sample concentration procedure. Measurements of ambient aerosol particle samples collected in Hong Kong show that the GC-MS approach is superior to the IC approach for the quantification of primary and secondary alkyl amines due to its lower detection limits and higher accuracy.

  16. Determining eligibility for antiretroviral therapy in resource-limited settings using total lymphocyte counts, hemoglobin and body mass index

    Directory of Open Access Journals (Sweden)

    Solberg Peter

    2007-01-01

    Full Text Available Abstract Background CD4+ T lymphocyte (CD4 cell count testing is the standard method for determining eligibility for antiretroviral therapy (ART, but is not widely available in sub-Saharan Africa. Total lymphocyte counts (TLCs have not proven sufficiently accurate in identifying subjects with low CD4 counts. We developed clinical algorithms using TLCs, hemoglobin (Hb, and body mass index (BMI to identify patients who require ART. Methods We conducted a cross-sectional study of HIV-infected adults in Uganda, who presented for assessment for ART-eligibility with WHO clinical stages I, II or III. Two by two tables were constructed to examine TLC thresholds, which maximized sensitivity for CD4 cell counts ≤ 200 cells μL, while minimizing the number offered ART with counts > 350 cells μL. Hb and BMI values were then examined to try to improve model performance. Results 1787 subjects were available for analysis. Median CD4 cell counts and TLCs, were 239 cells/μL and 1830 cells/μL, respectively. Offering ART to all subjects with a TLCs ≤ 2250 cells/μL produced a sensitivity of 0.88 and a false positive ratio of 0.21. Algorithms that treated all patients with a TLC 3000 cells/μL, and used Hb and/or BMI values to determine eligibility for those with TLC values between 2000 and 3000 cells/μL, marginally improved accuracy. Conclusion TLCs appear useful in predicting who would be eligible for ART based on CD4 cell count criteria. Hb and BMI values may be useful in prioritizing patients for ART, but did not improve model accuracy.

  17. Study on the applicability of a precise, accurate method for rapid evaluation of engine and lubricant performance. [determination of wear metal in used lubricating oils

    Science.gov (United States)

    Kinard, J. T.

    1975-01-01

    The development of a procedure for obtaining data related to wear metal determinations in used lubricants is discussed. The procedure makes it possible to obtain rapid, simultaneous determinations of a number of wear metals at levels of parts per thousand to low parts per billion using a small amount of sample. The electrode assembly and instrumentation used in the process are described. Samples of data obtained from tests conducted under controlled conditions are tabulated.

  18. Determination of anxiolytic veterinary drugs from biological fertilizer blood meal using liquid chromatography high-resolution mass spectrometry.

    Science.gov (United States)

    Choi, Jeong-Heui; Lamshöft, Marc; Zühlke, Sebastian; Park, Jong-Hyouk; Rahman, Md Musfiqur; Abd El-Aty, A M; Spiteller, Michael; Shim, Jae-Han

    2014-06-01

    A liquid environment-friendly agricultural material originating from animal blood, blood meal, was employed to detect anxiolytic veterinary drugs using a combination of liquid-liquid extraction (LLE) and positive electrospray ionization Orbitrap mass spectrometry. Every positive ion of the analytes was consistent with [M+H](+) , and the accurate mass analysis and mass spectral filtration with a 2-ppm mass tolerance window were applied to identify and quantitate the analytes and metabolites. The developed LLE method was validated with the lowest calibrated level, linearity (r(2) ), recovery, repeatability and the within-laboratory reproducibility, which were in the ranges of 0.3-1 µg/L, 0.9963-0.9995, 48.3-117.5%, 1.1-12.6% and 2.3-15.7%, respectively. The LLE method was compared with a solid-phase extraction (SPE) method; however, its recoveries were liquid blood meal samples, and none of the targeted compounds were observed.

  19. Simultaneous determination of 15 nitroimidazoles in cosmetics by HPLC coupled with electrospray ionization- tandem mass spectrometry.

    Science.gov (United States)

    Meng, Xian-Shuang; Bai, Hua; Zhang, Qing; Lv, Qing; Chen, Yun-Xia; Ma, Hui-Juan; Li, Jing-Rui; Ma, Qiang

    2014-01-01

    A sensitive and reliable analytical method based on HPLC/MSIMS has been developed for the simultaneous determination of 15 nitroimidazoles in cosmetics. A diversity of cosmetic samples, including powder, lotion, shampoo, and cream were collected. The samples were ultrasonically extracted with aqueous methanol, and the extracts were then subjected to cleanup bySPE using an Oasis HLB cartridge followed by filtration with a 0.20 pm membrane filter. Afterwards, chromatographic separation was performed on an XSelect CSH C18 column (2.1 x 150 mm, 3.5 pm) maintained at 30°C within 15 min by a gradient of acetonitrile-0.1% aqueous formic acid solution at a flow rate of 0.25 mL/min. The mass spectrometric detection was carried, out using electrospray positive ionization under the multiple reaction monitoring mode. A good linearity was observed over the concentration range from 0.5 to 500 ng/mL. The intraday and interday precisions, which were investigated by determining all target compounds in cosmetics seven times/day and on 7 consecutive days, were below 5.00%. The mean recoveries at three spiked levels ranged from 80.42 to 100.83% with the RSDs from 0.45 to 9.02%. The LOQs were determined to be between 0.01 and 0.1 mg/kg. The method was sufficiently rapid, reliable, and sensitive for the determination of 15 nitroimidazoles in cosmetics.

  20. Determination of abacavir, tenofovir, darunavir, and raltegravir in human plasma and saliva using liquid chromatography coupled with tandem mass spectrometry.

    Science.gov (United States)

    Yamada, Eiko; Takagi, Ritsuo; Sudo, Koji; Kato, Shingo

    2015-10-10

    A liquid chromatography-tandem mass spectrometry assay for the determination of abacavir (ABC), tenofovir (TFV), darunavir (DRV), and raltegravir (RAL) in human plasma and saliva was developed and validated to investigate the applicability of saliva as an appropriate specimen for therapeutic drug monitoring. As internal standards, TFV was chosen for ABC, ABC was chosen for TFV, RAL for DRV, and DRV for RAL. Sample preparation involved protein precipitation with acetonitrile, evaporation of solvent using a centrifugal evaporator, and reconstitution by dissolving the residue in mobile phase. Liquid chromatography was performed on a C18 reverse phase column (1.5 × 50 mm, 5 μm) isocratically at a flow rate of 0.2 mL/min using 5mM formic acid-3% (v/v) acetonitrile as the mobile phase for ABC and TFV and 5mM formic acid-35% (v/v) acetonitrile as the mobile phase for DRV and RAL. The run time was 6 min, and the retention time was approximately 2.0 min for TFV, 2.5 min for RAL, and 4-4.5 min for ABC and DRV. Analytes were detected using tandem mass spectrometry in positive electrospray ionization mode. The precursor/product ion transitions (m/z) were 287.3/191.2 for ABC, 288.5/176.2 for TFV, 548.3/392.3 for DRV, and 445.3/109.5 for RAL, and were monitored on a triple-quadrupole mass spectrometer operated in the multiple reaction monitoring mode. The linearity of the assay was assessed in the range 1-10,000 ng/mL for all four drugs. Within-run and between-run mean accuracy, precision, and the extraction recovery for all drugs were -14.5-18.1%, 1.2-13.1%, and 86.0-111.1%, respectively. The proposed assay is sufficiently sensitive and accurate to quantify these drugs in plasma and saliva, and is suitable for investigating the relationship between drug concentrations in plasma and saliva.

  1. On the determination of the crystal-vapor surface free energy, and why a Gaussian expression can be accurate for a system far from Gaussian

    Science.gov (United States)

    Modak, Viraj P.; Wyslouzil, Barbara E.; Singer, Sherwin J.

    2016-08-01

    The crystal-vapor surface free energy γ is an important physical parameter governing physical processes, such as wetting and adhesion. We explore exact and approximate routes to calculate γ based on cleaving an intact crystal into non-interacting sub-systems with crystal-vapor interfaces. We do this by turning off the interactions, ΔV, between the sub-systems. Using the soft-core scheme for turning off ΔV, we find that the free energy varies smoothly with the coupling parameter λ, and a single thermodynamic integration yields the exact γ. We generate another exact method, and a cumulant expansion for γ by expressing the surface free energy in terms of an average of e-βΔV in the intact crystal. The second cumulant, or Gaussian approximation for γ is surprisingly accurate in most situations, even though we find that the underlying probability distribution for ΔV is clearly not Gaussian. We account for this fact by developing a non-Gaussian theory for γ and find that the difference between the non-Gaussian and Gaussian expressions for γ consist of terms that are negligible in many situations. Exact and approximate methods are applied to the (111) surface of a Lennard-Jones crystal and are also tested for more complex molecular solids, the surface of octane and nonadecane. Alkane surfaces were chosen for study because their crystal-vapor surface free energy has been of particular interest for understanding surface freezing in these systems.

  2. DIURNAL CHANGES IN PLASMA-LEVELS OF 2-PYRROLIDINONE DETERMINED BY ISOTOPE-DILUTION MASS-SPECTROMETRY

    NARCIS (Netherlands)

    VANDENBERG, GA; WOLTHERS, BG; NAGEL, GT; MUSKIET, FAJ; BANGHMAN, S; DEZEEUW, RA

    1991-01-01

    A new capillary gas chromatographic method with mass spectrometric detection for the determination of 2-pyrrolidinone was developed. Using quantification based on stable isotope dilution mass spectrometry by monitoring selected ions in the ammonia chemical ionization mode diurnal changes of 2-pyrrol

  3. Phase shifts and nonellipsoidal light curves: Challenges from mass determinations in x-ray binary stars

    Science.gov (United States)

    Cantrell, Andrew Glenn

    We consider two types of anomalous observations which have arisen from efforts to measure dynamical masses of X-ray binary stars: (1) Radial velocity curves which seemingly show the primary and the secondary out of antiphase in most systems, and (2) The observation of double-waved light curves which deviate significantly from the ellipsoidal modulations expected for a Roche lobe filling star. We consider both problems with the joint goals of understanding the physical origins of the anomalous observations, and using this understanding to allow robust dynamical determinations of mass in X-ray binary systems. In our analysis of phase-shifted radial velocity curves, we discuss a comprehensive sample of X-ray binaries with published phase-shifted radial velocity curves. We show that the most commonly adopted explanation for phase shifts is contradicted by many observations, and consider instead a generalized form of a model proposed by Smak in 1970. We show that this model is well supported by a range of observations, including some systems which had previously been considered anomalous. We lay the groundwork for the derivation of mass ratios based on our explanation for phase shifts, and we discuss the work necessary to produce more detailed physical models of the phase shift. In our analysis of non-ellipsoidal light curves, we focus on the very well-studied system A0620-00. We present new VIH SMARTS photometry spanning 1999-2007, and supplement this with a comprehensive collection of archival data obtained since 1981. We show that A0620-00 undergoes optical state changes within X-ray quiescence and argue that not all quiescent data should be used for determinations of the inclination. We identify twelve light curves which may reliably be used for determining the inclination. We show that the accretion disk contributes significantly to all twelve curves and is the dominant source of nonellipsoidal variations. We derive the disk fraction for each of the twelve curves

  4. Performance of a Micro-Strip Gas Chamber for event wise, high rate thermal neutron detection with accurate 2D position determination

    Science.gov (United States)

    Mindur, B.; Alimov, S.; Fiutowski, T.; Schulz, C.; Wilpert, T.

    2014-12-01

    A two-dimensional (2D) position sensitive detector for neutron scattering applications based on low-pressure gas amplification and micro-strip technology was built and tested with an innovative readout electronics and data acquisition system. This detector contains a thin solid neutron converter and was developed for time- and thus wavelength-resolved neutron detection in single-event counting mode, which improves the image contrast in comparison with integrating detectors. The prototype detector of a Micro-Strip Gas Chamber (MSGC) was built with a solid natGd/CsI thermal neutron converter for spatial resolutions of about 100 μm and counting rates up to 107 neutrons/s. For attaining very high spatial resolutions and counting rates via micro-strip readout with centre-of-gravity evaluation of the signal amplitude distributions, a fast, channel-wise, self-triggering ASIC was developed. The front-end chips (MSGCROCs), which are very first signal processing components, are read out into powerful ADC-FPGA boards for on-line data processing and thereafter via Gigabit Ethernet link into the data receiving PC. The workstation PC is controlled by a modular, high performance dedicated software suite. Such a fast and accurate system is crucial for efficient radiography/tomography, diffraction or imaging applications based on high flux thermal neutron beam. In this paper a brief description of the detector concept with its operation principles, readout electronics requirements and design together with the signals processing stages performed in hardware and software are presented. In more detail the neutron test beam conditions and measurement results are reported. The focus of this paper is on the system integration, two dimensional spatial resolution, the time resolution of the readout system and the imaging capabilities of the overall setup. The detection efficiency of the detector prototype is estimated as well.

  5. Simultaneous determination of bromine and chlorine in coal using electrothermal vaporization inductively coupled plasma mass spectrometry and direct solid sample analysis.

    Science.gov (United States)

    de Gois, Jefferson S; Pereira, Éderson R; Welz, Bernhard; Borges, Daniel L G

    2014-12-10

    A new method for the direct analysis of coal using electrothermal vaporization inductively coupled plasma mass spectrometry and direct solid sample analysis was developed, aiming at the determination of Br and Cl. The procedure does not require any significant sample pretreatment and allows simultaneous determination of both elements to be carried out, requiring small mass aliquots of sample (about 0.5 mg). All operating parameters, including carrier gas flow-rate and RF power, were optimized for maximum sensitivity. The use of modifiers/aerosol carriers (Pd, Pd+Al and Pd+Ca) was evaluated, and the mixture of Pd and Ca was chosen, allowing pyrolysis and vaporization temperatures of 700°C and 1900°C, respectively. Chlorine was accurately determined using calibration against solid standards, whereas Br could also be determined using calibration against aqueous standard solutions. The limits of quantification were 0.03 μg g(-1) for Br and 7 μg g(-1) for Cl, and no spectral interferences were observed.

  6. Determination of free and ethoxylated alkylphenols in leather with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Ma, He-Wei; Cheng, Ya

    2010-12-10

    An analytical approach was developed to determine nonylphenol (NP), octylphenol (OP), nonylphenol ethoxylates (NPEO(n)) and octylphenol ethoxylates (OPEO(n)) in leather samples involving the conversion of NPEO(n) and OPEO(n) into the corresponding NP and OP. The four targets were extracted from samples using ultrasonic-assisted acetonitrile extraction. NP and OP in the extracts were directly isolated with hexane and quantitatively determined with 4-n-nonylphenol as internal standard by gas chromatography-mass spectrometry (GC-MS). For NPEO(n) and OPEO(n) in the extracts, they were first converted into NP and OP with aluminum triiodide as cleavage agent, and the yielded NP and OP were determined by GC-MS. The contents of NPEO(n) and OPEO(n) were calculated by normalizing to NPEO(9) and OPEO(9), respectively. This method was properly validated and the real sample tests revealed the pollution significance of leather by NPEO(n) and OPEO(n).

  7. [Determination of clavulanic acid residue in milk by high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Yang, Gang; Huang, Xianhui; Guo, Chunna; Fang, Qiuhua; He, Limin

    2012-06-01

    An analytical method was developed for the determination of clavulanic acid (CLAV) in milk by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). A 2 g milk sample was deproteinized by ethanol. The supernatant was transferred into a pear-shaped bottle to be evaporated to about 0.5 mL, and the residue was dissolved with ammonium acetate solution. The sample was determined by HPLC-MS/MS after the purification. The chromatographic separation was achieved on a Luna 5u C8 column using 0.1% formic acid in water and acetonitrile as mobile phases with gradient elution. The identification of CLAV was carried out by MS/MS equipped with electrospray ionization in negative scanning and multiple reaction monitoring (MRM) modes. Matrix-matched calibration standard was used for the quantification. The calibration curve showed perfect linear in the range of 10 - 400 microg/kg with the correlation coefficient of 0.999. The limit of detection (LOD, S/N > or = 3) was 10 microg/kg in milk, and the limit of quantification (LOQ, S/N > or = 10) was 20 microg/kg. The mean recoveries varied from 80.00% to 91.25% at the four spiked levels of LOQ, 1/2MRL (the maximum residue limit), MRL, and 2MRL with the relative standard deviations of 5.60% -8.77%. In conclusion, the established method can be applied for the determination of CLAV residues in milk.

  8. Determining Membrane Protein-Lipid Binding Thermodynamics Using Native Mass Spectrometry.

    Science.gov (United States)

    Cong, Xiao; Liu, Yang; Liu, Wen; Liang, Xiaowen; Russell, David H; Laganowsky, Arthur

    2016-04-06

    Membrane proteins are embedded in the biological membrane where the chemically diverse lipid environment can modulate their structure and function. However, the thermodynamics governing the molecular recognition and interaction of lipids with membrane proteins is poorly understood. Here, we report a method using native mass spectrometry (MS), to determine thermodynamics of individual ligand binding events to proteins. Unlike conventional methods, native MS can resolve individual ligand binding events and, coupled with an apparatus to control the temperature, determine binding thermodynamic parameters, such as for protein-lipid interactions. We validated our approach using three soluble protein-ligand systems (maltose binding protein, lysozyme, and nitrogen regulatory protein) and obtained similar results to those using isothermal titration calorimetry and surface plasmon resonance. We also determined for the first time the thermodynamics of individual lipid binding to the ammonia channel (AmtB), an integral membrane protein from Escherichia coli. Remarkably, we observed distinct thermodynamic signatures for the binding of different lipids and entropy-enthalpy compensation for binding lipids of variable chain length. Additionally, using a mutant form of AmtB that abolishes a specific phosphatidylglycerol (PG) binding site, we observed distinct changes in the thermodynamic signatures for binding PG, implying these signatures can identify key residues involved in specific lipid binding and potentially differentiate between specific lipid binding sites.

  9. MALDI-TOF mass spectrometric determination of eight benzodiazepines with two of their metabolites in blood.

    Science.gov (United States)

    Nozawa, Hideki; Minakata, Kayoko; Yamagishi, Itaru; Hasegawa, Koutaro; Wurita, Amin; Gonmori, Kunio; Suzuki, Osamu; Watanabe, Kanako

    2015-05-01

    A rapid and sensitive method was developed for the determination of benzodiazepines and benzodiazepine-like substances (BZDs) by matrix-assisted laser desorption ionization (MALDI)-time-of-flight (TOF)-mass spectrometry (MS). In this method, α-cyano-4-hydroxy cinnamic acid was used as the matrix to assist the ionization of BZDs. Determination of 8 BZDs (with two of their metabolites) belonging to top 12 medical drugs detected in poisonous cases in Japan, was performed using diazepam-d5 as the internal standard. The limit of detection of zolpidem was 0.07ng/ml with its quantification range of 0.2-20ng/ml in blood, in the best case, and the limit of detection of flunitrazepam was 2ng/ml with its quantification range of 6-200ng/ml in blood, in the worst case. The spectra of zopiclone in MALDI-MS and MS/MS were different from those in electrospray ionization MS and MS/MS. Present method provides a simple and high throughput method for the screening of these BZDs using only 20μl of blood. The developed method was successfully used for the determination of BZDs in biological fluids obtained from two victims.

  10. On-line coupling of solid-phase extraction with mass spectrometry for the analysis of biological samples. II. Determination of clenbuterol in urine using multiple-stage mass spectrometry in an ion-trap mass spectrometer

    NARCIS (Netherlands)

    van Hout, MWJ; Hofland, CM; Niederlander, HAG; de Jong, GJ

    2000-01-01

    Solid-phase extraction (SPE) was coupled to ion-trap mass spectrometry to determine clenbuterol in urine. For SPE a cartridge exchanger was used and, after extraction, the eluate was directly introduced into the mass spectrometer, For two types of cartridges, i.e. C-18 and polydivinylbenzene (PDVB),

  11. Effect of various initiators on molar mass determination of hydrolyzed potato starch-acrylamide graft copolymers

    Directory of Open Access Journals (Sweden)

    Đorđević Suzana

    2013-01-01

    Full Text Available This study is concerned with synthesis, characterization and properties of graft copolymer produced from hydrolyzed potato starch and acrylamide using various initiators (azobisisobutyronitrile, potassium persulfate and benzoyl peroxide. Starch hydrolysis was performed in order to reduce molecular mass. Acrylamide was grafted on shorter starch macromolecules creating side branches on the main chain resulting in a product that could be used in textile finishing more successfully. Various initiators were used, primarily, to produce graft monomer on the starch and also to obtain thinner or thicker packaging of side chains that can have a great influence on the behavior of textile yarns impregnated with these copolymers. Benzoyl peroxide, as initiator, proved to be very successful in grafting of acrylamide on hydrolyzed starch, in terms of yield, graft percentage and efficiency results. Grafting in the presence of azobisisobutyronitrile and potassium persulfate as initiators has slightly better monomer to polymer conversion values. FTIR spectra of hydrolyzed and grafted starch confirm by their characteristic bands that grafting was successful. Residual amounts of monomer in copolymer and molar mass distribution were determined by chromatography. Results show that the highest quantity of monomer is found in the sample of hydrolyzed starch grafted in the presence of potassium persulfate. Molar masses of hydrolysate and copolymer show differences ranging from 1∙102 to 2∙107 g/mol. Results of sizing using grafted starch show that sized yarns had higher strength (tenacity and lower elongation. Grafted hydrolyzed starch, as an agent for cotton yarn sizing, gives better results than non grafted starch, especially regarding sizing uniformity, yarn mechanical parameters and easier removal in following desizing process.

  12. Direct determinations of the nucleon and pion σ terms at nearly physical quark masses

    Science.gov (United States)

    Bali, Gunnar S.; Collins, Sara; Richtmann, Daniel; Schäfer, Andreas; Söldner, Wolfgang; Sternbeck, André; RQCD Collaboration

    2016-05-01

    We present a high statistics study of the pion and nucleon light and strange quark sigma terms using Nf=2 dynamical nonperturbatively improved clover fermions with a range of pion masses down to mπ˜150 MeV and several volumes, L mπ=3.4 up to 6.7, and lattice spacings, a =0.06 - 0.08 fm , enabling a study of finite volume and discretization effects for mπ≳260 MeV . Systematics are found to be reasonably under control. For the nucleon we obtain σπ N=35 (6 ) MeV and σs=35 (12 ) MeV , or equivalently in terms of the quark fractions, fTu=0.021 (4 ) , fTd=0.016 (4 ) and fTs=0.037 (13 ) , where the errors include estimates of both the systematic and statistical uncertainties. These values, together with perturbative matching in the heavy quark limit, lead to fTc=0.075(4 ), fT b=0.072 (2 ) and fT t=0.070 (1 ). In addition, through the use of the (inverse) Feynman-Hellmann theorem our results for σπ N are shown to be consistent with the nucleon masses determined in the analysis. For the pion we implement a method which greatly reduces excited state contamination to the scalar matrix elements from states traveling across the temporal boundary. This enables us to demonstrate the Gell-Mann-Oakes-Renner expectation σπ=mπ/2 over our range of pion masses.

  13. Determination of the uncertainties in the theoretical mass isotopomer distribution of molecules.

    Science.gov (United States)

    García Alonso, J Ignacio; Rodríguez-González, P; González-Gago, A; González-Antuña, A

    2010-04-01

    A procedure for the determination of the uncertainties in the theoretical mass isotopomer distribution of molecules due to natural variations in the isotope composition of their constituting elements is described here for the first time. For this purpose, a Visual Basic macro for Microsoft Excel was written by adapting the direct stepwise calculation algorithm published by Kubinyi (Anal. Chim. Acta 1991, 247, 107-119, Fig. 1). In our procedure no pruning threshold factors were used to eliminate round up errors for large molecules. Then, the Kragten procedure of uncertainty propagation (Analyst 1994, 119, 2161-2165) was applied taking into account the correlation coefficients between the isotope abundances of the corresponding atoms. For bi-isotopic elements (C, H, N, Cl, Br) the correlation coefficients were given the value of -1. For tri- and tetra-isotopic elements the correlation coefficients were calculated using the mass dependent fractionation law used in stable isotope geochemistry and values of +1 or -1 were obtained depending on the isotope system considered. It was observed that for small organic molecules of natural isotope abundances, such as phenol or polybrominated diphenylethers, the method provided relatively small propagated uncertainties similar in magnitude to those measured experimentally. For (13)C-labelled molecules the calculated uncertainties were mainly due to the uncertainties in the isotope enrichment of (13)C and were much larger than the experimental uncertainties. For large molecules of natural isotope abundances, such as peptide C(68)H(107)N(17)O(25) (NIST 8327 RM), the uncertainties in their mass isotopomer distributions were much larger and their source could be assigned mainly to the uncertainty of the natural isotope composition of carbon. When the size of the molecule was even larger, such as bovine insulin (C(254)H(377)N(65)O(75)S(6)), Kragten procedure provided a good estimate for the uncertainty when the most probable isotope

  14. Rapid and accurate hplc-dad method for the determination of the herbicide bispyribac-sodium in surface water, and its validation

    Directory of Open Access Journals (Sweden)

    Márcia H. S. Kurz

    2009-01-01

    Full Text Available A new method is described for the determination of the herbicide bispyribac-sodium in surface water, especially from river and irrigated rice water samples. The method involves extraction in solid phase and quantification by high performance liquid chromatography with diode array detection (HPLC-DAD. After optimization of the extraction and separation parameters, the method was validated. The method presented average recoveries of 101.3 and 97.7%, under repeatability and intermediate precision conditions, respectively, with adequate precision (RSD from 0.9 to 7.5%. The method was applied for the determination of bispyribac-sodium in surface water samples with a limit of detection of 0.1 μg L-1.

  15. Monolithic molecularly imprinted solid-phase extraction for the selective determination of trace cytokinins in plant samples with liquid chromatography-electrospray tandem mass spectrometry.

    Science.gov (United States)

    Du, Fuyou; Ruan, Guihua; Liang, Shenghua; Xie, Fuwei; Liu, Huwei

    2012-08-01

    Cytokinins (CTKs) are a class of growth-regulating hormones involved in various physiological and developmental processes. More novel analytical methods for the accurate identification and quantitative determination of trace CTKs in plants have been desired to better elucidate the roles of CTKs. In this work, a novel method based on monolithic molecularly imprinted solid-phase extraction followed by liquid chromatography-electrospray tandem mass spectrometry (mMI-SPE-LC-MS/MS) was developed for accurate determination of four CTKs in plant samples. The molecularly imprinted polymer monolith was prepared by using kinetin as the template in syringes and exhibited specific recognition ability for the four CTKs in comparison with that of non-imprinted polymer monolith. Several factors affecting the extraction performance of mMI-SPE, including the pH of loading sample solution, the nature and volume of elution solvent, the flow rate of sample loading, and sample volume, were investigated, respectively. Under the optimized conditions, the proposed mMI-SPE-LC-MS/MS method was successfully applied in the selective extraction and determination of four CTKs in plant tissues, and it offers detection limits (S/N = 3) of 104, 113, 130, and 89 pg/mL and mean recoveries of 85.9%, 79.3%, 73.5%, and 70.1% for kinetin, kinetin glucoside, trans-zeatin, and meta-topolin (mT), respectively, with the corresponding RSDs less than 15%.

  16. Determination of biogenic amines in beer and wine by capillary electrophoresis-tandem mass spectrometry.

    Science.gov (United States)

    Daniel, Daniela; Dos Santos, Vagner Bezerra; Vidal, Denis Tadeu Rajh; do Lago, Claudimir Lucio

    2015-10-16

    A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the simultaneous assessment of nine biogenic amines (spermine, spermidine, putrescine, cadaverine, histamine, phenylethylamine, tryptamine, tyramine, and urocanic acid) in commercial samples of beer and wine is introduced. The samples were submitted to a simple clean-up step with poly(vinylpolypyrrolidone) followed by filtration. Electrophoretic separation in a polyvinyl alcohol (PVA)-coated capillary using 0.5 mol L(-1) acetic acid (pH 2.5) as background electrolyte and detection by electrospray-tandem mass spectrometry was employed. The range of the correlation coefficients of the calibration curves of the analyzed compounds was 0.996-0.999, and the limits of detection and limits of quantification were in the range of 1-2 μg L(-1) and 3-8 μg L(-1), respectively. The recovery values for samples spiked at three concentration levels (0.2, 0.5, and 1.0 mg L(-1)) ranged from 87 to 113% with standard deviation not greater than 5.8%. The use of a PVA-coated silica capillary allows suppressing the electroosmotic flow and, consequently, increasing of the separation efficiency. The method was successfully used to determine biogenic amines in commercial samples of beer and wine.

  17. Determination of tolperisone in human plasma by liquid chromatography/tandem mass spectrometry for clinical application.

    Science.gov (United States)

    Choi, Chang-Ik; Park, Jung-In; Lee, Hye-In; Lee, Yun-Jeong; Jang, Choon-Gon; Bae, Jung-Woo; Lee, Seok-Yong

    2012-12-12

    We have developed and validated a simple, rapid, and sensitive liquid chromatography analytical method employing tandem mass spectrometry (LC-MS/MS) for the determination of tolperisone, a centrally acting muscle relaxant, in human plasma. After liquid-liquid extraction with methyl t-butyl ether, chromatographic separation of tolperisone was performed using a reversed-phase Luna C(18) column (2.0mm×50mm, 5μm particles) with a mobile phase of 10mM ammonium formate buffer (pH 3.5) - methanol (12:88, v/v) and quantified by tandem mass detection in ESI positive ion mode. The flow rate of the mobile phase was 250μL/min and the retention times of tolperisone and the internal standard (IS, dibucaine) were both 0.6min. The calibration curves were linear over a range of 0.5-300ng/mL (r>0.999). The lower limit of quantification, using 200μL human plasma, was 0.5ng/mL. The mean accuracy and precision for intra- and inter-day validation of tolperisone were within acceptable limits. The LC-MS/MS method reported here showed improved sensitivity for quantification of tolperisone in human plasma compared with previously described analytical methods. Lastly, the validated method was successfully applied to a pharmacokinetic study in humans.

  18. Determination of dissolved naphthenic acids in natural waters by using negative-ion electrospray mass spectrometry.

    Science.gov (United States)

    Headley, John V; Peru, Kerry M; McMartin, Dena W; Winkler, Marcus

    2002-01-01

    Naphthenic acids (NAs) have been implicated as some of the most toxic substances in oil sands leachates and identified as priority substances impacting on aquatic environments. As a group of compounds, NAs are not well characterized and comprise a large group of saturated aliphatic and alicyclic carboxylic acids found in hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils). Described is an analytical method using negative-ion electrospray ionization mass spectrometry (ES/MS) of extracts. Preconcentration was achieved by using a solid-phase extraction procedure utilizing a crosslinked polystyrene-based polymer with acetonitrile elution. Recovery of the Fluka Chemicals NA mixture was highly pH-dependent, with 100% recovery at pH 3.0, but only 66 and 51% recoveries at pHs 7 and 9, respectively. The dissolved phase of the NA was very dependent on sample pH. It is thus critical to measure the pH and determine the appropriate mass profiles to identify NAs in natural waters. The ES/MS analytical procedure proved to be a fast and sensitive method for the recovery and detection of NAs in natural waters, with a detection limit of 0.01 mg/L.

  19. Determination of mycophenolic acid in human plasma by ultra performance liquid chromatography tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Vivek Upadhyay

    2014-06-01

    Full Text Available A simple, sensitive and high throughput ultra performance liquid chromatography tandem mass spectrometry method has been developed for the determination of mycophenolic acid in human plasma. The method involved simple protein precipitation of MPA along with its deuterated analog as an internal standard (IS from 50 µL of human plasma. The chromatographic analysis was done on Acquity UPLC C18 (100 mm×2.1 mm, 1.7 µm column under isocratic conditions using acetonitrile and 10 mM ammonium formate, pH 3.00 (75:25, v/v as the mobile phase. A triple quadrupole mass spectrometer operating in the positive ionization mode was used for quantitation. In-source conversion of mycophenolic glucuronide metabolite to the parent drug was selectively controlled by suitable optimization of cone voltage, cone gas flow and desolvation temperature. The method was validated over a wide concentration range of 15–15000 ng/mL. The mean extraction recovery for the analyte and IS was >95%. Matrix effect expressed as matrix factors ranged from 0.97 to 1.02. The method was successfully applied to support a bioequivalence study of 500 mg mycophenolate mofetil tablet in 72 healthy subjects.

  20. Absolute densities, masses, and radii of the WASP-47 system determined dynamically

    CERN Document Server

    Almenara, J M; Bonfils, X; Udry, S

    2016-01-01

    We present a self-consistent modelling of the available light curve and radial velocity data of WASP-47 that takes into account the gravitational interactions between all known bodies in the system. The joint analysis of light curve and radial velocity data in a multi-planetary system allows deriving absolute densities, radii, and masses without the use of theoretical stellar models. For WASP-47 the precision is limited by the reduced dynamical information that is due to the short time span of the K2 light curve. We achieve a precision of around 22% for the radii of the star and the transiting planets, between 40% and 60% for their masses, and between 1.5% and 38% for their densities. All values agree with previously reported measurements. When theoretical stellar models are included, the system parameters are determined with a precision that exceeds that achieved by previous studies, thanks to the self-consistent modelling of light curve and radial velocity data.