Search results for "IONIZATION"
showing 10 items of 1255 documents
High-performance liquid chromatographic, capillary electrophoretic and capillary electrophoretic–electrospray ionisation mass spectrometric analysis …
2002
Systems for efficient separation of selected alkaloid groups by high performance liquid chromatography (HPLC), capillary electrophoresis (CE) and capillary electrophoresis coupled with electrospray ionisation mass spectrometry (CE-ESI-MS) are described. The optimized HPLC system was applied for the separation of 23 standard indole alkaloids as well as for qualitative and quantitative analyses of crude alkaloid extracts of Rauvolfia serpentina X Rhazya stricta hybrid cell cultures. The developed conditions for CE analysis proved to be efficient for separation of mixtures of standard indole and beta-carboline alkaloids. The described buffer system is also applicable in the combination of CE w…
Harrison-Zel'dovich primordial spectrum is consistent with observations
2010
Inflation predicts primordial scalar perturbations with a nearly scale-invariant spectrum and a spectral index approximately unity (the Harrison--Zel'dovich (HZ) spectrum). The first important step for inflationary cosmology is to check the consistency of the HZ primordial spectrum with current observations. Recent analyses have claimed that a HZ primordial spectrum is excluded at more than 99% c.l.. Here we show that the HZ spectrum is only marginally disfavored if one considers a more general reionization scenario. Data from the Planck mission will settle the issue.
Impact of general reionization scenarios on extraction of inflationary parameters
2010
Determination of whether the Harrison-Zel'dovich spectrum for primordial scalar perturbations is consistent with observations is sensitive to assumptions about the reionization scenario. In light of this result, we revisit constraints on inflationary models using more general reionization scenarios. While the bounds on the tensor-to-scalar ratio are largely unmodified, when different reionization schemes are addressed, hybrid models are back into the inflationary game. In the general reionization picture, we reconstruct both the shape and amplitude of the inflaton potential. We discuss how relaxing the simple reionization restriction affects the reconstruction of the potential through the c…
Ion mobility spectrometry evaluation of cocaine occupational exposure in forensic laboratories
2014
An approach, based on ion mobility spectrometry (IMS) has been developed for the control of cocaine in air of the breathing zone of operators, in laboratory surfaces and in nasal mucus of employees to evaluate cocaine exposure in a forensic laboratory. The analytical methodology has been validated in terms of accuracy, precision and limits of detection and results obtained were statistically comparable with those obtained by liquid chromatography. Cocaine concentration in laboratory air increases from 100 ± 35 ng m(-3) of a normal day to 10,000 ng m(-3) during the manipulation of cocaine seizures. The occupational exposure limit (OEL) for cocaine has not been established which difficult the…
Cyclic Dinuclear Organotin Cations Stabilized by Bulky Substituents
2015
The syntheses of sterically congested 2,2-bis(diorganochloridostannyl)propane, Me2C(SnClR2)2 (1; R = CH(SiMe3)2), the related salts [cyclo-{Me2C(SnR2)2X}B(ArF)4] (2, X = Cl; 3, X = OAc; 4, X = OH; ArF = 3,5-(CF3)2C6H3), and the four-membered-ring cyclo-{Me2C(SnR2)2O} (5) are reported. The compounds have been characterized by elemental and EDX analyses, 1H, 11B, 13C, 19F, 29Si, and 119Sn NMR and IR spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction analysis.
Toward multifunctional single-molecule magnets: characterization of dodecanuclear manganese complexes by electrospray ionization mass spectrometry.
2001
Single-molecule magnets (SMM) based on the dodecanuclear manganese complexes Mn12O12(RCOO)16 can be readily characterized by electrospray ionization mass spectrometry. This facilitates the synthesis of complex multifunctional molecules that have potential use in the organization of SMM into films or surfaces.
Tellurium( II ) Dialkanethiolates: n p (S)‐σ*(Te−S′) Orbital Interactions Determine the 125 Te NMR Chemical Shift, and the Molecular and Crystal Stru…
2003
Tellurium(II) dimethanethiolate, Te(SMe)(2), and tellurium(II) diethanethiolate, Te(SEt)(2), were synthesized by reaction of TeO2 and Te(OiPr)(4) with HSMe and HSEt, respectively. In the solid state, Te(SMe)(2) exhibits a cis-conformation of the methyl groups with respect to the TeS2 plane - an unprecedented situation for nonfunctionalized organotrichalcogenides - whereas Te(SEt)(2) shows a trans-conformation. Ab initio calculations performed for Te(SMe)(2) and Te(SEt)(2) show that the cis- and trans-conformers represent minima on the potential energy surface and are stabilized by intramolecular pi-type n(S)-sigma* (Te-S') orbital interactions. In the solid state, the molecules of each comp…
Fragmentations and reactions of the organophosphate insecticide Diazinon and its oxygen analog Diazoxon studied by electrospray ionization ion trap m…
2005
The fragmentations and reactions of Diazinon and related compounds have been studied by electrospray ionization ion trap mass spectrometry. Several novel fragmentation and rearrangements have been observed, including an intramolecular thiono-thiolo rearrangement. The stability, in the gas-phase, of the protomers of 2-isopropyl-4-methyl-6-pyrimidinol has been demonstrated. The complexity of the gas phase ion processes observed suggest that, at present, caution Should be exercised in using this approach for the analysis of environmental and other samples until our understanding of these processes increases considerably. (J Am Soc Mass Spectrom 2005, 16, 515-523) (c) 2005 American Society for …
Confirmation of Fenthion Metabolites in Oranges by IT-MS and QqTOF-MS
2007
14 pages, 4 figures, 4 tables.-- PMID: 18020315 [PubMed].-- Printed version published Dec 15, 2007.
Phantom development for daily checks in electron intraoperative radiotherapy with a mobile linac.
2020
Abstract Purpose IORT with mobile linear accelerators is a well-established modality where the dose rate and, therefore, the dose per pulse are very high. The constancy of the dosimetric parameters of the accelerator has to be checked daily. The aim of this work is to develop a phantom with embedded detectors to improve both accuracy and efficiency in the daily test of an IORT linac at the surgery room. Methods The developed phantom is manufactured with transparent polymethyl methacrylate (PMMA), allocating 6 parallel-plate chambers: a central one to evaluate the on-axis beam output, another on-axis one placed at a fixed depth under the previous one to evaluate the energy constancy and four…