Search results for " ionization"
showing 10 items of 621 documents
Antioxidant Bibenzyl Derivatives from Notholaena nivea Desv.
2011
Four new bibenzyl derivatives were isolated, together with other known bibenzyls, by bioassay-guided fractionation of a CHCl3-MeOH extract of Notholaena nivea Desv. (Pteridaceae) aerial parts. The structures were elucidated by NMR, ESIMS and other spectral analyses. Their antioxidative effects towards superoxide, lipidic peroxidation and the 2,2'- azino-bis-3- ethilbenzothiazoline-6-sulfonic acid (ABTS) radical were assayed. Results showed that the compound 3,12-dihydroxy-5-methoxybibenzyl (6) is the most active compound in the ABTS free-radical scavenging test, while in the coupled oxidation of ȕ-carotene and linoleic acid assay the compound 5,12-dihydroxy-3-methoxydibenzyl-6- carboxylic a…
Plasma pharmacokinetics and tissue distribution study of cajaninstilbene acid in rats by liquid chromatography with tandem mass spectrometry
2010
Cajaninstilbene acid (CSA; 3-hydroxy-4-prenyl-5-methoxystilbene-2-carboxylic acid) is a major active constituent of pigeonpea leaves, has been proven to be effective in clinical treatment of diabetes, hepatitis, measles and dysentery. A rapid and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of CSA in rat plasma and various tissues (brain, heart, lung, liver, spleen, small intestine and kidney) of rat for the first time. Rat plasma and tissue distribution pre-treated by protein precipitation with acetoacetate was analyzed using LC-MS/MS with an electrospray ionization (ESI) interface, and isoliquiritigenin was us…
Transition probabilities for BrII lines emitted from a wall-stabilized cascade arc
2000
Abstract Absolute transition probabilities of the eleven Br II lines were measured in emission. A plasma created in a wall-stabilized arc at atmospheric pressure in the mixture of argon and bromine vapors was used as the excitation source. The relative transition probabilities were converted to an absolute scale based on a lifetime value measured by the electron impact method. The results were compared with experimental data. Discrepancies have been found to be outside the experimental uncertainties.
Low energy electrons and ultra-soft X-rays irradiation of plasmid DNA. Technical innovations
2016
Abstract In this paper we present in a first part the latest results of our group which are in relation with the study of DNA damages inflicted by low energy electrons (0-20 eV) in ultra-high vacuum as well as in air under atmospheric conditions. A short description of the drop-casting technique we developed to produce thin and nanometre-scaled DNA layers onto graphite sheets is given. We provide the absolute cross-section for loss of supercoiled topology of plasmid DNA complexed with 1,3-diaminopropane (Dap) in the vacuum under 10 eV electron impact and suggest a specific pathway for the dissociation of the transient negative ion formed by resonant capture of such a low energy electron (LE…
A complementary laser system for ISOLDE RILIS
2011
The Resonance Ionization Laser Ion Source (RILIS) is a powerful tool for efficient and selective production of radioactive ion beams at Isotope Separator On Line (ISOL) facilities. To avoid isobaric background, highly selective stepwise resonant ionization is applied, using up to three different laser wavelengths. Due to their advantages in terms of stability and reliability, an all solid-state titanium:sapphire (Ti:Sa) system is used or is planned to be installed at the majority of on-line facilities worldwide. Such an all solid-state Ti:Sa laser system is going to be installed at the ISOLDE RILIS at CERN alongside the well-established dye laser system.
Two-color ionization of hydrogen by short intense pulses
2010
Photoelectron energy spectra resulting by the interaction of hydrogen with two short pulses having carrier frequencies, respectively, in the range of the infrared and XUV regions have been calculated. The effects of the pulse duration and timing of the X-ray pulse on the photoelectron energy spectra are discussed. Analysis of the spectra obtained for very long pulses show that certain features may be explained in terms of quantum interferences in the time domain. It is found that, depending on the duration of the X-ray pulse, ripples in the energy spectra separated by the infrared photon energy may appear. Moreover, the temporal shape of the low frequency radiation field may be inferred by …
High-resolution laser system for the S3-Low Energy Branch
2022
International audience; In this paper we present the first high-resolution laser spectroscopy results obtained at the GISELE laser laboratory of the GANIL-SPIRAL2 facility, in preparation for the first experiments with the S$^3$-Low Energy Branch. Studies of neutron-deficient radioactive isotopes of erbium and tin represent the first physics cases to be studied at S$^3$. The measured isotope-shift and hyperfine structure data are presented for stable isotopes of these elements. The erbium isotopes were studied using the $4f^{12}6s^2$$^3H_6 \rightarrow 4f^{12}(^3 H)6s6p$$J = 5$ atomic transition (415 nm) and the tin isotopes were studied by the $5s^25p^2 (^3P_0) \rightarrow 5s^25p6s (^3P_1)$…
A Series of MIICuII3 Stars (M = Mn, Ni, Cu, Zn) Exhibiting Unusual Magnetic Properties
2014
The work in this report describes the syntheses, electrospray ionization mass spectromtery, structures, and experimental and density functional theoretical (DFT) magnetic properties of four tetrametallic stars of composition [M(II)(Cu(II)L)3](ClO4)2 (1, M = Mn; 2, M = Ni; 3, M = Cu; 4, M = Zn) derived from a single-compartment Schiff base ligand, N,N'-bis(salicylidene)-1,4-butanediamine (H2L), which is the [2 + 1] condensation product of salicylaldehyde and 1,4-diaminobutane. The central metal ion (Mn(II), Ni(II), Cu(II), or Zn(II)) is linked with two μ2-phenoxo bridges of each of the three [Cu(II)L] moieties, and thus the central metal ion is encapsulated in between three [Cu(II)L] units. …
RADIOISOTOPE MASS SPECTROMETRY
2003
Mass spectrometric methods are very sensitive and enable in many cases a multielement determination of trace and ultratrace elements combined with a good isotopic analysis ( Bacon et al. , 2001 ). Therefore, these techniques are also applied for the detection of long-lived radionuclides ( Becker and Dietze, 2000 ) mainly in environmental samples ( Adriaens et al. , 1992 ; Bailey et al. , 1993 ; Bibler et al. , 1998 ; Eroglu et al. , 1998 ; Edmonds et al. , 1998 ; Becker and Dietze, 1999 ; Wendt et al. , 1999 ), nuclear materials ( Betti, 1997 ; Chartier et al. , 1999 ), glass and ceramics ( Rohr et al. , 1994 ; Fukuda and Sayama, 1997 ), and in high-purity substances ( Beer and Heumann, 199…
Novel bioactive bromopyrrole alkaloids from the Mediterranean sponge Axinella verrucosa
2005
The Mediterranean sponge Axinella verrucosa has been investigated for its alkaloid composition and has been found to produce a complex mixture of bromopyrrole alkaloids. Along with the previously isolated compounds 5-18, four novel alkaloids of this class, compounds 1-4, have been isolated, and their structures established through spectroscopic methods. Compounds 1-4 were found to display neuroprotective activity against the agonists serotonin and glutamate in vitro.