A compact electron cyclotron resonance negative hydrogen ion source for evaluation of plasma electrode materials.

A compact ion source that produces hydrogen plasma with an electron cyclotron resonance (ECR) configuration combined with a 2-stage extraction system with a single aperture of 6 mm diameter has been designed and built to study the performance of different materials as the plasma electrode (PE) of a negative hydrogen ion source. The source has the capability to electrically bias the PE with respect to the ECR plasma. The first experiment with low ECR power input (less than 40 W) was carried out. The PE of the C12A7 electride showed the largest H- current among aluminum, molybdenum, and the C12A7 electride.

Positive and negative hydrogen ion reflections of low-energy atomic and molecular hydrogen ion beam from HOPG and Mo surfaces.

Positive and negative hydrogen ion reflections from surfaces by injecting singly charged hydrogen ion beams show a clear difference between atomic and molecular ion injections at low energy and grazing incidence. The intensity ratio of reflected negative to positive ions H-/H+ increased as the incident beam energy per nucleon decreased only when molecular ion beams are injected. It implies that negative ions are more produced upon beam-surface interaction when molecules are injected. A possible reason was discussed in terms of difference in the negative ion production processes between atomic and molecular ions.

Identifying Double Bond Positions in Phospholipids Using Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry Based on Oxygen Attachment Dissociation.

Lipids, a class of biomolecules, play a significant role in the physiological system. In this study, gas-phase hydroxyl radicals (OH·) and atomic oxygens (O) were introduced into the collision cell of a triple quadruple mass spectrometer (TQ-MS) to determine the positions of the double bond in unsaturated phospholipids. A microwave-driven compact plasma generator was used as the OH·/O source. The reaction between OH·/O and the precursor ions passing through the collision cell generates product ions that correspond to the double bond positions in the fatty acyl chain. This double bond position specific fragmentation process initiated by the attachment of OH·/O to the double bond of a fatty acyl chain is a characteristic of oxygen attachment dissociation (OAD). A TQ-MS incorporating OAD, in combination with liquid chromatography, permitted a high throughput analysis of the double bond positions in complex biomolecules. It is important to know the precise position of double bonds in lipids, since these molecules can have widely different functionalities based on the position of the double bonds. The assignment of double bond positions in a mixture of eight standard samples of phosphatidylcholines (phospholipids with choline head groups) with multiple saturated fatty acyl chains attached was successfully demonstrated.

Structural Analysis of Phospholipid Using Hydrogen Abstraction Dissociation and Oxygen Attachment Dissociation in Tandem Mass Spectrometry.

Gas-phase hydrogen radicals were introduced into a quadrupole ion trap containing singly charged phospholipids to obtain structural fragmentation patterns in tandem mass spectrometry (MS/MS). Saturated and unsaturated phosphatidylcholines were used as a model phospholipid, whose chain-length ranges between 16 and 24. The MS/MS spectrum yielded a continuous series of fragment ions with a mass difference of 14 Da, representing the saturated fatty acyl chains. The fragment ions corresponding to the double-bond position within a single fatty acyl chain showed a characteristic mass difference of 12 Da. The detection of these diagnostic product ions enabled the structural analysis of double-bond isomers of phospholipids. To further investigate the potential of radical-induced dissociation for the isomeric analysis of phospholipids, gas-phase hydroxyl radicals, and triplet oxygen atoms were employed in tandem mass spectrometry. The methylene bridges adjacent to the double-bond positions were selectively dissociated, accompanied by oxidation of the double bonds. Tandem mass spectrometry incorporating multiple radical species facilitates the structural analysis of isomeric phospholipids.

Tandem Mass Spectrometry of Peptide Ions by Microwave Excited Hydrogen and Water Plasmas.

A thermal cracking cell that served as the atomic hydrogen source for hydrogen attachment/abstraction dissociation (HAD) analysis has an intrinsic problem to produce a beam of atoms reactive against heated tungsten capillary. A plasma excited by 2.45 GHz microwave discharge can deliver reactive species to a quadrupole ion trap confining analyte ions without excessive heating of the radical source components. The radical (H•) production performance of the developed source was evaluated by optical emission spectroscopy and H• attachment reaction to fullerene ions. The source exhibited the H• attachment rate as high as a thermal cracking source forming H• in the high temperature tungsten capillary to induce fragmentation processes preserving post-translational modifications. Water vapor was introduced to the source to confirm the stability to generate oxygen containing radicals, which were found present in the water vapor plasma together with atomic hydrogen. Injection of radicals from a water vapor plasma successfully dissociated peptide ions to c-/z- and a-/x-type ions as the case of HAD induced by a thermal cracking cell.

Validation of the Coronary Artery Bypass Graft SYNTAX Score (Synergy Between Percutaneous Coronary Intervention With Taxus) as a Prognostic Marker for Patients With Previous Coronary Artery Bypass Graft Surgery After Percutaneous Coronary Intervention.

BACKGROUND: The efficacy and prognosis of percutaneous coronary intervention (PCI) as secondary revascularization in patients with previous coronary artery bypass graft surgery remain uncertain. METHODS AND RESULTS: We retrospectively evaluated 434 consecutive patients with previous coronary artery bypass graft surgery hospitalized for PCI between 2004 and 2011 (men 84%, age 71 (interquartile range, 66-76) years) and calculated the coronary artery bypass graft Synergy Between Percutaneous Coronary Intervention With Taxus score (CSS) before (baseline CSS) and after PCI (post-PCI CSS). Patients were divided into 2 groups based on median post-PCI CSS: low-score (≤23; n=217) and high-score groups (>23; n=217). Major adverse cardiovascular events (MACE) were defined as the composite of cardiovascular death, myocardial infarction, and unplanned repeat revascularization for myocardial ischemia. The median baseline and post-PCI CSS were 30 (interquartile range, 21-40) and 23 (interquartile range, 14.5-33.5), respectively. During a median follow-up of 69 months, the prevalence of MACE and cardiac death differed significantly between the 2 post-PCI CSS groups (MACE: low, 13.8%; high, 28.6%; P<0.001; cardiac death: low, 6.2%; high, 16.7%; P=0.002). In multivariable analysis, the high post-PCI CSS divided by the median was associated with substantially greater cumulative MACE (hazard ratio, 2.09; 95% confidence interval, 1.31-3.34; P=0.002) and cardiac death (hazard ratio, 2.02; 95% confidence interval, 1.03-3.98; P=0.042) compared with the low post-PCI CSS. Net reclassification improvement analysis revealed that post-PCI CSS resulted in significantly improved prediction of MACE and cardiac death compared with baseline CSS. CONCLUSIONS: In this external validation study, the CSS was a potential prognostic factor after subsequent PCI, even for previous coronary artery bypass graft surgery patients.