Search results for "IONIZATION"
showing 10 items of 1255 documents
Comparison of two methods skipping cell lysis and protein extraction for identification of bacteria from blood cultures by matrix-assisted laser deso…
2019
ABSTRACT Objective Matrix-assisted laser desorption/ionization time-of-flight mass-spectrometry (MALDI-TOF MS) is widely used for fast identification of bacteria from blood cultures (BC). We compared the performance of two procedures, one including a pre-enrichment step in brain heart infusion and the other a direct method using vacutainer separator gel tubes (DI), for identification of bacteria from blood cultures by MALDI-TOF MS. Material and methods We first prepared a training set of 20 simulated bacteremia specimens, including 10 Gram-negative and 10 Gram-positive species. A total of 145 non-consecutive BCs flagged as positive (68 Gram-negative rods, and 77 Gram-positive cocci) were pr…
MALDI-TOF mass spectrometry identification of filamentous fungi in the clinical laboratory.
2014
Pôle MERS F. Dalle; International audience; This study aimed to validate the effectiveness of a standardised procedure for the MALDI-TOF mass spectrometry (MS)-based identification on a large sample of filamentous fungi routinely identified in university hospitals' laboratories. Non-dermatophyte filamentous fungi prospectively isolated in the routine activity of five teaching hospitals in France were first identified by conventional methods in each laboratory and then by MS in one centre. DNA sequence-based identification resolved discrepancies between both methods. In this study, of the 625 analysed filamentous fungi of 58 species, 501 (80%) and 556 (89%) were correctly identified by conve…
A Multicentre Pilot Study of a Two-Tier Newborn Sickle Cell Disease Screening Procedure with a First Tier Based on a Fully Automated MALDI-TOF MS Pla…
2019
The reference methods used for sickle cell disease (SCD) screening usually include two analytical steps: a first tier for differentiating haemoglobin S (HbS) heterozygotes, HbS homozygotes and β-thalassemia from other samples, and a confirmatory second tier. Here, we evaluated a first-tier approach based on a fully automated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) platform with automated sample processing, a laboratory information management system and NeoSickle® software for automatic data interpretation. A total of 6701 samples (with high proportions of phenotypes homozygous (FS) or heterozygous (FAS) for the inherited genes for sickle h…
Initial results of NEXT-DEMO, a large-scale prototype of the NEXT-100 experiment
2013
NEXT-DEMO is a large-scale prototype of the NEXT-100 detector, an electroluminescent time projection chamber that will search for the neutrinoless double beta decay of Xe-136 using 100-150 kg of enriched xenon gas. NEXT-DEMO was built to prove the expected performance of NEXT-100, namely, energy resolution better than 1% FWHM at 2.5MeV and event topological reconstruction. In this paper we describe the prototype and its initial results. A resolution of 1.75% FWHM at 511 keV (which extrapolates to 0.8% FWHM at 2.5 MeV) was obtained at 10 bar pressure using a gamma-ray calibration source. Also, a basic study of the event topology along the longitudinal coordinate is presented, proving that it…
Radiopurity control in the NEXT-100 double beta decay experiment: procedures and initial measurements
2013
[EN] The "Neutrino Experiment with a Xenon Time-Projection Chamber" (NEXT) is intended to investigate the neutrinoless double beta decay of Xe-136, which requires a severe suppression of potential backgrounds. An extensive screening and material selection process is underway for NEXT since the control of the radiopurity levels of the materials to be used in the experimental set-up is a must for rare event searches. First measurements based on Glow Discharge Mass Spectrometry and gamma-ray spectroscopy using ultra-low background germanium detectors at the Laboratorio Subterraneo de Canfranc (Spain) are described here. Activity results for natural radioactive chains and other common radionucl…
Carbonate-coordinated metal complexes precede the formation of liquid amorphous mineral emulsions of divalent metal carbonates†
2011
During the mineralisation of metal carbonates MCO3 (M = Ca, Sr, Ba, Mn, Cd, Pb) liquid-like amorphous intermediates emerge. These intermediates that form via a liquid/liquid phase separation behave like a classical emulsion and are stabilized electrostatically. The occurrence of these intermediates is attributed to the formation of highly hydrated networks whose stability is mainly based on weak interactions and the variability of the metal-containing pre-critical clusters. Their existence and compositional freedom are evidenced by electrospray ionization mass spectrometry (ESI-MS). Liquid intermediates in non-classical crystallisation pathways seem to be more common than assumed.
Squaric acid mediated chemoselective PEGylation of proteins: reactivity of single-step-activated α-amino poly(ethylene glycol)s.
2012
The covalent attachment of poly(ethylene glycol) (PEG) to therapeutically active proteins (PEGylation) has become an important method to deal with the pharmacological difficulties of these polypeptides, such as short body-residence times and immunogenicity. However, the derivatives of PEG used for PEGylation lack further functional groups that would allow the addition of targeting or labeling moieties. Squaric acid diethyl ester was used for the chemoselective single-step activation of poly(ethylene glycol)s into the respective ester amides. The resultant selective protein-reactive poly(ethylene glycol)s were investigated with respect to their selectivity towards amino acid residues in bovi…
Triplet-triplet energy transfer controlled by the donor-acceptor distance in rigidly held palladium-containing cofacial bisporphyrins.
2005
Eleven new complexes, including mono-, heterobi-, and homobimetallic cofacial bisporphyrins, (Pd)H 2 DPS, (M)H 2 DPX, (M)H 2 DPB, (PdZn)DPS, (PdZn)DPX, (Pt) 2 DPX, (M) 2 DPB (M=Pd, Pt), and (Pt)P (DPS 4 - = 4,6-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]dibenzothiophene tetraanion, DPX 4 - = 4,5-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]-9,9-dimethylxanthene tetraanion, DPB 4 - =1,8-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]biphenylene tetraanion, P 2 - = 5-phenyl-2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrin dianion) have been synthesized and characterized. The photophysical properties of the donor (M)P (M=Pd or Pt, P= porphy…
Novel O-antigen of Hafnia alvei PCM 1195 lipopolysaccharide with a teichoic acid-like structure
2009
Abstract The lipopolysaccharide (LPS) of Hafnia alvei strain PCM 1195 was obtained by the hot phenol/water method. The O-specific polysaccharide was released by mild acidic hydrolysis and isolated by gel filtration. The structure of the O-specific polysaccharide was investigated by 1 H, 13 C, and 31 P NMR spectroscopy, MALDI-TOF MS, and GC–MS, accompanied by monosaccharide and methylation analysis. It was concluded that the O-specific polysaccharide is composed of a hexasaccharide repeating units interlinked with a phosphate group: {→4-α- d -Glc p -(1→3)-α- l - Fuc p NAc-(1→3)-[α- d -Glc p -(1→4)]-α- d -Glc p NAc-(1→3)-α- l - Fuc p NAc-(1→4)-α- d -Glc p -(1→P} n .
End Capping Ring-Opening Olefin Metathesis Polymerization Polymers with Vinyl Lactones
2008
The selective placement of a functional group at the chain end of a ring-opening metathesis polymer using ruthenium carbene initiators has been a significant limitation. Here we demonstrate a highly effective and facile end-capping technique for ROMP with living ruthenium carbene chain ends using single-turnover olefin metathesis substrates. Vinylene carbonate and 3H-furanone are introduced as functionalization and termination agents for the ruthenium-initiated ring-opening metathesis polymerization. This leads directly to the formation of functional polymer end groups without further chemical transformation steps. Aldehyde and carboxylic acid end groups can be introduced by this new method…