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https://www.readbyqxmd.com/read/29779386/gas-analysis-by-electron-ionization-combined-with-chemical-ionization-in-a-compact-ft-icr-mass-spectrometer
#1
Michel Heninger, Hélène Mestdagh, Essyllt Louarn, Gérard Mauclaire, Pierre Boissel, Julien Leprovost, Elsa Bauchard, Sebastien Thomas, Joel Lemaire
In this paper, a compact Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer based on a permanent magnet is presented. This instrument has been developed for real-time analysis of gas emissions. The instrument is well suited to industrial applications or analysis of toxic and complex samples where the concentrations can vary rapidly on a wide range. The novelty of this instrument is the ability to use either electron ionization (EI) or chemical ionization (CI) individually or both of them alternatively...
May 20, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29756920/absence-of-cyclotron-resonance-in-the-anomalous-metallic-phase-in-ino_-x
#2
Youcheng Wang, I Tamir, D Shahar, N P Armitage
It is observed that many thin superconducting films with not too high disorder level (generally R_{N}/□<2000  Ω) placed in magnetic field show an anomalous metallic phase where the resistance is low but still finite as temperature goes to zero. Here we report in weakly disordered amorphous InO_{x} thin films that this anomalous metal phase possesses no cyclotron resonance and hence non-Drude electrodynamics. The absence of a finite frequency resonant mode can be associated with a vanishing downstream component of the vortex current parallel to the supercurrent and an emergent particle-hole symmetry of this metal, which establishes its non-Fermi-liquid character...
April 20, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29756886/first-direct-observation-of-runaway-electron-driven-whistler-waves-in-tokamaks
#3
D A Spong, W W Heidbrink, C Paz-Soldan, X D Du, K E Thome, M A Van Zeeland, C Collins, A Lvovskiy, R A Moyer, M E Austin, D P Brennan, C Liu, E F Jaeger, C Lau
DIII-D experiments at low density (n_{e}∼10^{19}  m^{-3}) have directly measured whistler waves in the 100-200 MHz range excited by multi-MeV runaway electrons. Whistler activity is correlated with runaway intensity (hard x-ray emission level), occurs in novel discrete frequency bands, and exhibits nonlinear limit-cycle-like behavior. The measured frequencies scale with the magnetic field strength and electron density as expected from the whistler dispersion relation. The modes are stabilized with increasing magnetic field, which is consistent with wave-particle resonance mechanisms...
April 13, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29756884/observation-of-poincar%C3%A3-andronov-hopf-bifurcation-in-cyclotron-maser-emission-from-a-magnetic-plasma-trap
#4
A G Shalashov, E D Gospodchikov, I V Izotov, D A Mansfeld, V A Skalyga, O Tarvainen
We report the first experimental evidence of a controlled transition from the generation of periodic bursts of electromagnetic radiation into the continuous-wave regime of a cyclotron maser formed in magnetically confined nonequilibrium plasma. The kinetic cyclotron instability of the extraordinary wave of weakly inhomogeneous magnetized plasma is driven by the anisotropic electron population resulting from electron cyclotron plasma heating in a MHD-stable minimum-B open magnetic trap.
April 13, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29751637/fast-profiling-of-natural-pigments-in-different-spirulina-arthrospira-platensis-dietary-supplements-by-di-ft-icr-and-evaluation-of-their-antioxidant-potential-by-pre-column-dpph-uhplc-assay
#5
Eduardo Sommella, Giulio Maria Conte, Emanuela Salviati, Giacomo Pepe, Alessia Bertamino, Carmine Ostacolo, Francesca Sansone, Francesco Del Prete, Rita Patrizia Aquino, Pietro Campiglia
Arthrospira platensis , better known as Spirulina, is one of the most important microalgae species. This cyanobacterium possesses a rich metabolite pattern, including high amounts of natural pigments. In this study, we applied a combined strategy based on Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) and Ultra High-Performance Liquid Chromatography (UHPLC) for the qualitative/quantitative characterization of Spirulina pigments in three different commercial dietary supplements. FT-ICR was employed to elucidate the qualitative profile of Spirulina pigments, in both direct infusion mode (DIMS) and coupled to UHPLC...
May 11, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29751541/compact-fticr-mass-spectrometry-for-real-time-monitoring-of-volatile-organic-compounds
#6
Joël Lemaire, Sébastien Thomas, Allan Lopes, Essyllt Louarn, Hélène Mestdagh, Hubert Latappy, Julien Leprovost, Michel Heninger
In this paper, we present a compact Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) designed for real time analysis of volatile organic compounds (VOCs) in air or in water. The spectrometer is based on a structured permanent magnet made with NdFeB segments. Chemical ionization is implemented inside the ICR cell. The most widely used reaction is the proton transfer reaction using H₃O⁺ precursor ions, but other ionic precursors can be used to extend the range of species that can be detected...
May 3, 2018: Sensors
https://www.readbyqxmd.com/read/29745348/automated-synthesis-of-68ga-dota-toc-methodological-aspects-and-suitable-technical-solutions-for-a-cationic-purification-system
#7
Licia Uccelli, Alessandra Boschi, Corrado Cittanti, Petra Martini, Luca Lodi, Elisa Zappaterra, Simona Romani, Samanta Zaccaria, Davide Cecconi, Ilaria Rambaldi, Ivan Santi, Stefano Panareo, Melchiore Giganti, Mirco Bartolomei
The PET Gallium-68 isotope has the advantage of being produced from a generator, so it is also available in nuclear medicine departments without a cyclotron. The preparation of Ga-68 DOTA-labelled compounds is actually performed by remotely controlled automated systems developed in order to assure production efficiency, reproducibility of the results, guarantee fast reaction time, to facilitate the synthesis and minimize the radiation exposure. Many automatic synthesis systems are available on the radiopharmaceutical market, and each of these requires the realization of some technical adaptations for routine use...
May 8, 2018: Current Radiopharmaceuticals
https://www.readbyqxmd.com/read/29741278/endo-or-exo-structures-of-gas-phase-alkali-metal-cation-aromatic-half-belt-complexes
#8
Yanyang Chen, Yasaman Jami-Alahmahdi, Kiran Sagar Unikela, Graham J Bodwell, Travis D Fridgen
1,1,9,9-Tetramethyl[9](2,11)teropyrenophane (TM9TP), a belt-shaped molecule, has a sizable cavity that molecules or ions could occupy. In this study, the question of whether TM9TP forms gas phase ion-molecule complexes with metal cations (K+, Rb+, Cs+) situated inside or outside the TM9TP cavity was addressed using both experimental and computational methods. Complexes were trapped in a Fourier transform ion cyclotron resonance mass spectrometer and their structures were explored by some novel physical chemistry/mass spectrometry methods...
May 9, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29740044/magnetic-resonance-probing-of-ground-state-in-the-mixed-valence-correlated-topological-insulator-smb-6
#9
S V Demishev, M I Gilmanov, A N Samarin, A V Semeno, N E Sluchanko, N A Samarin, A V Bogach, N Yu Shitsevalova, V B Filipov, M S Karasev, V V Glushkov
Introducing of topological insulator concept for fluctuating valence compound - samarium hexaboride - has recently initiated a new round of studies aimed to clarify the nature of the ground state in this extraordinary system with strong electron correlations. Here we discuss the data of magnetic resonance in the pristine single crystals of SmB6 measured in 60 GHz cavity experiments at temperatures 1.8-300 K. The microwave study as well as the DC resistivity and Hall effect measurements performed for the different states of SmB6 [110] surface prove definitely the existence of the layer with metallic conductivity increasing under lowering temperature below 5 K...
May 8, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29736654/in-depth-molecular-characterization-and-biodegradability-of-water-extractable-organic-nitrogen-in-erhai-lake-sediment
#10
Li Zhang, Shengrui Wang, Jiachun Yang, Kechen Xu
Dissolved organic nitrogen (DON) constitutes a significant fraction of the total dissolved nitrogen content of most aquatic systems and is thus a major nitrogen source for bacteria and phytoplankton. The present work applied Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to a compound-level analysis of the depth-dependent molecular composition of water-extractable organic nitrogen (WEON) in lake sediment. The study focused on Erhai Lake, China. It was found that a large portion (from 16...
May 8, 2018: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29736636/the-effect-of-work-system-on-the-hand-exposure-of-workers-in-18-f-fdg-production-centres
#11
Małgorzata Wrzesień
The production of the 18 F isotope-the marker of deoxyglucose (18 F-FDG)-the radiopharmaceutical most commonly used in the oncological diagnostic technique of positron emission tomography, requires a cyclotron device. At present, there are nine facilities working in Poland that are equipped with cyclotrons used for producing the short-lived isotopes. The aim of the paper is to determine the hand exposure of workers employed in the two 18 F-FDG production centres taking in to account the production procedures and work system in those facilities...
May 7, 2018: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/29731686/parallel-detection-in-a-single-icr-cell-spectral-averaging-and-improved-s-n-without-increased-acquisition-time
#12
Sung-Gun Park, Gordon A Anderson, James E Bruce
Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is well-renowned for its ultrahigh resolving power and mass measurement accuracy. As with other types of analytical instrumentation, achievable signal-to-noise ratio (S/N) is an important analytical figure of merit with FTICR-MS. S/N can be improved with higher magnetic fields and longer time-domain signal acquisition periods. However, serial signal averaging of spectra or time-domain signals acquired with multiple ion populations is most commonly used to improve S/N...
April 2018: International Journal of Mass Spectrometry
https://www.readbyqxmd.com/read/29719628/novel-water-soluble-lignin-derivative-bp-cx-1-identification-of-components-and-screening-of-potential-targets-in-silico-and-in-vitro
#13
Elena I Fedoros, Alexey A Orlov, Alexander Zherebker, Ekaterina A Gubareva, Mikhail A Maydin, Andrey I Konstantinov, Konstantin A Krasnov, Ruben N Karapetian, Ekaterina I Izotova, Sergey E Pigarev, Andrey V Panchenko, Margarita L Tyndyk, Dmitry I Osolodkin, Evgeny N Nikolaev, Irina V Perminova, Vladimir N Anisimov
Identification of molecular targets and mechanism of action is always a challenge, in particular - for natural compounds due to inherent chemical complexity. BP-Cx-1 is a water-soluble modification of hydrolyzed lignin used as the platform for a portfolio of innovative pharmacological products aimed for therapy and supportive care of oncological patients. The present study describes a new approach, which combines in vitro screening of potential molecular targets for BP-Cx-1 using Diversity Profile - P9 panel by Eurofins Cerep (France) with a search of possible active components in silico in ChEMBL - manually curated chemical database of bioactive molecules with drug-like properties...
April 6, 2018: Oncotarget
https://www.readbyqxmd.com/read/29716347/spectroscopic-method-to-study-low-charge-state-ion-and-cold-electron-population-in-ecris-plasma
#14
R Kronholm, T Kalvas, H Koivisto, O Tarvainen
The results of optical emission spectroscopy experiments probing the cold electron population of a 14 GHz Electron Cyclotron Resonance Ion Source (ECRIS) are reported. The study has been conducted with a high resolution spectrometer and data acquisition setup developed specifically for the diagnostics of weak emission line characteristic to ECRIS plasmas. The optical emission lines of low charge state ions and neutral atoms of neon have been measured and analyzed with the line-ratio method. The aforementioned electron population temperature of the cold electron population (Te < 100 eV) is determined for Maxwell-Boltzmann and Druyvesteyn energy distributions to demonstrate the applicability of the method...
April 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29716322/a-tandem-mass-spectrometer-for-crossed-beam-irradiation-of-mass-selected-molecular-systems-by-kev-atomic-ions
#15
Lucas Schwob, Mathieu Lalande, Jean-Yves Chesnel, Alicja Domaracka, Bernd A Huber, Sylvain Maclot, Jean-Christophe Poully, Jimmy Rangama, Patrick Rousseau, Violaine Vizcaino, Lamri Adoui, Alain Méry
In the present paper, we describe a new home-built crossed-beam apparatus devoted to ion-induced ionization and fragmentation of isolated biologically relevant molecular systems. The biomolecular ions are produced by an electrospray ionization source, mass-over-charge selected, accumulated in a 3D ion trap, and then guided to the extraction region of an orthogonal time-of-flight mass spectrometer. Here, the target molecular ions interact with a keV atomic ion beam produced by an electron cyclotron resonance ion source...
April 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29714486/melanoma-imaging-using-18-f-labeled-%C3%AE-melanocyte-stimulating-hormone-derivatives-with-positron-emission-tomography
#16
Chengcheng Zhang, Zhengxing Zhang, Kuo-Shyan Lin, Joseph Lau, Jutta Zeisler, Nadine Colpo, David M Perrin, Francois Benard
Melanocortin 1 receptor (MC1R) is specifically expressed in the majority of melanomas, a leading cause of death related to skin cancers. Accurate staging and early detection is crucial in managing melanoma. Based on the α-melanocyte-stimulating hormone (αMSH) sequence, MC1R-targeted peptides have been studied for melanoma imaging, predominately for use with single-photon emission computed tomography (SPECT), with few attempts made for positron emission tomography (PET). 18 F is a commonly used PET isotope due to readily available cyclotron production, pure positron emission and a favorable half-life (109...
May 1, 2018: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/29701972/characterization-of-brominated-disinfection-byproducts-formed-during-the-chlorination-of-aquaculture-seawater
#17
Juan Wang, Zhineng Hao, Fengqiong Shi, Yongguang Yin, Dong Cao, Ziwei Yao, Jing-Fu Liu
Although brominated disinfection byproducts (Br-DBPs) have been reported to form from reactions between bromide, dissolved organic matter (DOM) and disinfectants, their formation during the disinfection of aquaculture seawater via chlorination has been rarely studied. Herein, after 5 days of disinfection of raw aquiculture seawater samples with sodium dichloroisocyanurate (NaDDC), trichloroisocyanuric acid (TCCA) and chlorine dioxide (ClO2), 181, 179 and 37 Br-DBPs were characterized by ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS)...
April 27, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29694134/rotational-energy-as-mass-in-h_-3-and-lower-limits-on-the-atomic-masses-of-d-and-3-he
#18
J A Smith, S Hamzeloui, D J Fink, E G Myers
We have made precise measurements of the cyclotron frequency ratios H_{3}^{+}/HD^{+} and H_{3}^{+}/^{3}He^{+} and observe that different H_{3}^{+} ions result in different cyclotron frequency ratios. We interpret these differences as due to the molecular rotational energy of H_{3}^{+} changing its inertial mass. We also confirm that certain high J, K rotational levels of H_{3}^{+} have mean lifetimes exceeding several weeks. From measurements with the lightest H_{3}^{+} ion we obtain lower limits on the atomic masses of deuterium and helium-3 with respect to the proton...
April 6, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29691781/characterization-of-harmonic-signal-acquisition-with-parallel-dipole-and-multipole-detectors
#19
Sung-Gun Park, Gordon A Anderson, James E Bruce
Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is a powerful instrument for the study of complex biological samples due to its high resolution and mass measurement accuracy. However, the relatively long signal acquisition periods needed to achieve high resolution can serve to limit applications of FTICR-MS. The use of multiple pairs of detector electrodes enables detection of harmonic frequencies present at integer multiples of the fundamental cyclotron frequency, and the obtained resolving power for a given acquisition period increases linearly with the order of harmonic signal...
April 24, 2018: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/29686408/anisotropic-magnetotransport-and-extremely-large-magnetoresistance-in-nbas-2-single-crystals
#20
G Peramaiyan, Raman Sankar, I Panneer Muthuselvam, Wei-Li Lee
We report the extremely large magnetoresistance and anisotropic magnetoresistance in a non-magnetic semimetallic NbAs2 single crystal. Unsaturated transverse XMR with quadratic field dependence has been observed to be ~3 × 105 % at 2 K and 15 T. Up to 12.5 K, clear Shubnikov de Haas (SdH) quantum oscillations were observed from which two distinct Fermi pockets were identified. The corresponding quantum electronic parameters such as effective cyclotron mass and Dingle temperature were obtained using Lifshitz-Kosevich formula...
April 23, 2018: Scientific Reports
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