Optimized Alkali-Metal Cationization in Secondary Ion Mass Spectrometry of Polyethylene Glycol Oligomers with up to m/z 10000: Dependence on Cation Species and Concentration.

In secondary ion mass spectrometry (SIMS), the detection of large organic molecules is accomplished using cluster ion bombardment. Ion formation often proceeds via cationization, through the attachment of (alkali) metal ions to the molecule. To study this process, the emission of secondary ions sputtered from polyethylene glycol (PEG) samples with molecular weights (MW) of 1000-10000 was examined. They were mixed with alkali-metal trifluoroacetic acid (X-TFA, where X = Li, Na, K, or Cs) in a wide range of concentrations to investigate the efficiency of cationization for 10 keV Ar2000+ cluster irradiation. Typically, cationized molecular ions [M + X]+ (with repeat units n of up to ∼250, corresponding roughly to m/z 11000) and some characteristic fragment species were observed in the mass spectra. For all alkali cations, the oligomer intensities increase strongly with the molecular composition ratios X-TFA/PEG in the samples, and values of 5-10 seem to be optimal. With increasing molecular weight, the intensity of oligomer ions relative to the total number of ions decreases; as the latter remains rather constant, this implies that more fragment species are formed. The ion yields (detected ions per primary ions) of cationized [M + Na]+ oligomers sputtered from a PEG decrease very strongly with their size n: from 5.2 × 10-6 at n = 21 (MW ∼ 1000) to 4.5 × 10-10 at n ∼ 245 (MW ∼ 11000). By contrast, the total yields Ytot+ show only a small variation for these different specimens, from 1.3 × 10-5 to 3.7 × 10-5.

Selective Reduction Mechanism of Graphene Oxide Driven by the Photon Mode versus the Thermal Mode.

A two-dimensional nanocarbon, graphene, has attracted substantial interest due to its excellent properties. The reduction of graphene oxide (GO) has been investigated for the mass production of graphene used in practical applications. Different reduction processes produce different properties in graphene, affecting the performance of the final materials or devices. Therefore, an understanding of the mechanisms of GO reduction is important for controlling the properties of functional two-dimensional systems. Here, we determined the average structure of reduced GO prepared via heating and photoexcitation and clearly distinguished their reduction mechanisms using ultrafast time-resolved electron diffraction, time-resolved infrared vibrational spectroscopy, and time-dependent density functional theory calculations. The oxygen atoms of epoxy groups are selectively removed from the basal plane of GO by photoexcitation (photon mode), in stark contrast to the behavior observed for the thermal reduction of hydroxyl and epoxy groups (thermal mode). The difference originates from the selective excitation of epoxy bonds via an electronic transition due to their antibonding character. This work will enable the preparation of the optimum GO for the intended applications and expands the application scope of two-dimensional systems.

Yields and images of secondary ions from organic materials by different primary Bi ions in time-of-flight secondary ion mass spectrometry.

RATIONALE: Bi cluster ions are used as a source of primary ions for time-of-flight secondary ion mass spectrometry (TOF-SIMS), and it has been recognized that secondary ion yields of macromolecules are higher with Bi cluster ions than with monomer ions or other cluster ions such as Cs(+), Ga(+) and Aun (+). However, the analysis conditions of Bi cluster TOF-SIMS are not sufficiently established. This study provides information on the secondary ion yields, damage cross-section and spatial resolution obtained with different primary Bi ions. METHODS: We investigated the secondary ion yields, damage cross-section and spatial resolution using three different primary Bi ions in TOF-SIMS. The primary ions selected were Bi1(+), Bi3(+) and Bi3(2)(+) that were accelerated with 25 kV and the positively charged secondary ions were analyzed. The samples were 1, 2-distearoyl-sn-glycero-3-phosphocholine (C44H88NO8P, DSPC), which is a typical lipid, and N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (C44H32N2, NPD) and 4,4',4"-tris[2-naphthyl(phenyl)amino]triphenylamine (C66H48N4, 2-TNATA), which are organic functional materials. RESULTS: Although the secondary ion yields of DSPC were highest when measured with Bi3(+), the spatial resolution obtained from all DSPC analyses could not be evaluated because of the low intensity of the secondary molecular ions. On the other hand, for both NPD and 2-TNATA, the secondary ion yields were highest when imaged with Bi3(2)(+). Also, we obtained the highest spatial resolution using Bi3(2)(+). In the analysis of all molecules, the damage cross-section obtained with Bi3(2)(+) was also the highest. CONCLUSIONS: When secondary ions were sensitively detected, images of the high spatial resolution were obtained by using Bi3(2)(+). On the other hand, when the secondary ion sensitivity was low, the spatial resolution depended on the yields of secondary ions, implying that the selection of the primary ion species is crucial for SIMS analysis of large molecules.

Cold ablation driven by localized forces in alkali halides.

Laser ablation has been widely used for a variety of applications. Since the mechanisms for ablation are strongly dependent on the photoexcitation level, so called cold material processing has relied on the use of high-peak-power laser fluences for which nonthermal processes become dominant; often reaching the universal threshold for plasma formation of ~1 J cm(-2) in most solids. Here we show single-shot time-resolved femtosecond electron diffraction, femtosecond optical reflectivity and ion detection experiments to study the evolution of the ablation process that follows femtosecond 400 nm laser excitation in crystalline sodium chloride, caesium iodide and potassium iodide. The phenomenon in this class of materials occurs well below the threshold for plasma formation and even below the melting point. The results reveal fast electronic and localized structural changes that lead to the ejection of particulates and the formation of micron-deep craters, reflecting the very nature of the strong repulsive forces at play.

Study on the detection limits of a new argon gas cluster ion beam secondary ion mass spectrometry apparatus using lipid compound samples.

RATIONALE: Ar gas cluster ion beam secondary ion mass spectrometry (Ar-GCIB SIMS) has been developed as one of the most powerful tools used for analyzing complex biological materials because of its distinctively high secondary ion yield of large organic molecules. However, for the practical analysis of minor components in complex biological materials, the sensitivity of the technique is still insufficient. METHODS: The detection limits of our original Ar-GCIB SIMS apparatus were investigated by measuring lipid compound samples in positive ion mode. The samples were mixtures of 1,2-distearoyl-sn-glycero-3-phosphocholine (C44 H88 NO8 P, DSPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (C40 H80 NO8 P, DPPC). The primary ions were accelerated with 10 keV and the mean cluster size was 1500. The secondary [M+H](+) ions emitted from the sample were analyzed using an orthogonal acceleration time-of-flight mass spectrometer (oa-TOF-MS). In addition, the isotope abundance ratio and the ratio of the [M+H](+) ion signal to the fragment ion signal acquired with Ar-GCIB SIMS were compared with those obtained with conventional Bi cluster SIMS. RESULTS: Secondary [M+H](+) ions and some characteristic fragment ions were clearly observed with high quantitative accuracy in the mass spectra acquired with Ar-GCIB SIMS. The results were clearly better than those obtained with conventional Bi cluster SIMS. CONCLUSIONS: The detection limit of Ar-GCIB SIMS was found to be below 0.1% and was much lower than that of conventional Bi cluster SIMS because of the high [M+H](+) ion yield and the low background. The results suggested that the new Ar-GCIB SIMS apparatus has the capability to acquire valuable information on complex biological materials.

Carney complex with right ventricular myxoma following second excision of left atrial myxoma.

We report a case of Carney complex with massive right ventricular myxoma after two-time excision of a left atrial myxoma. The patient was a 45-year-old woman with pyrexia. She temporarily lost consciousness during examination, and echocardiography and computed tomography (CT) showed a massive tumor in the right ventricle. Loss of consciousness was determined to be caused by intracardiac obstruction of blood flow due to the tumor, and corrective surgery was performed. Pathological findings indicated myxoma with no malignancy. Myxomas are benign, but there is frequent recurrence of tumors associated with Carney complex. Because her myxomas were accompanied by unusual skin pigmentation, she was diagnosed with Carney complex. Carney complex has a high rate of myxoma recurrence, and often runs in families. In all cases, it is necessary to observe the patient's course closely.

Peptide dissociation patterns in secondary ion mass spectrometry under large argon cluster ion bombardment.

RATIONALE: The analysis of organic and biological substances by secondary ion mass spectrometry (SIMS) has greatly benefited from the use of cluster ions as primary bombarding species. Thereby, depth profiling and three-dimensional (3D) imaging of such systems became feasible. Large Ar(n)(+) cluster ions may constitute a further improvement in this direction. METHODS: To explore this option, large Ar(n)(+) cluster ions (with n ~1500 Ar atoms per cluster) were used to investigate the emission of positive secondary ions from two peptide specimens (angiotensin I and bradykinin) by orthogonal time-of-flight SIMS using bombarding energies 6, 10 and 14 keV. RESULTS: For both peptides, the protonated molecular ion is observed in the mass spectra. In addition, distinct fragmentation patterns were observed; these indicate that fragment ions under Ar cluster irradiation form primarily via cleavage of bonds along the peptide backbone whereas the rapture of side chains occurs much less frequently. These features appear to be similar to low-energy collision-induced dissociation pathways. CONCLUSIONS: Tentatively, these findings can then be ascribed to the concerted action of the large number of Ar atoms in the impact zone of cluster at the surface: these low-energy Ar species (with an average energy of few eV) may effect the cleavage of the peptide bonds and lead, eventually, to the emission of the fragment ions.

Late Lower Extremity Ischemia due to Thrombi in an Occluded Graft after Axillary-Femoral Artery Bypass.

We experienced a rare case of acute ischemia of the lower extremity due to embolism caused by an occluded prosthetic graft late after axillary-femoral artery bypass. A 67-year-old woman developed acute right lower extremity ischemia 7 years after axillary-femoral artery bypass, which had been performed for lower limb ischemia as a complication of acute aortic dissection (Stanford B). The graft was occluded, and the native vessel had re-canalized by the time of the present admission. She was successfully treated by disconnection of the graft followed by revascularization.

Invasive group A streptococcal infection in pregnancy.

We conducted a literature review of 55 pregnancies with symptomatic Group A streptococcus (Streptococcus pyogenes) infection reported in English (20 cases), French (2 cases) and Japanese (33 cases) to seek ways of improving prognosis. Multiparous women (83% [39/47]) in the third trimester (90% [47/52]) were prone to infection from winter to spring (75% [21/28]). Onset was heralded by flu-like symptoms, such as high fever (94% [46/49]), with upper respiratory (40% [22/55]) and/or gastrointestinal symptoms (49% [27/55]). Characteristic findings were early onset of shock (91% [50/55]) and infection-induced strong uterine contraction (73% [40/55]) suggestive of placental abruption. The clinical course was too acute and severe to rescue the mother (58% [32/55] died) and/or infant (66% [39/59] died). However, outcome has improved over the last decade, with rescue of 68% (15/22) of the mothers since 2000, and early use of antibiotics (71% [22/31] survived) and use of intravenous immunoglobulin (91% [10/11] survived) were associated with favourable outcome. Early use of antibiotics and intravenous immunoglobulin may improve outcome of pregnant women suffering from flu-like symptoms, shock and strong uterine contractions suggestive of placental abruption.

Molecular depth profiling of multilayer structures of organic semiconductor materials by secondary ion mass spectrometry with large argon cluster ion beams.

In this study, we present molecular depth profiling of multilayer structures composed of organic semiconductor materials such as tris(8-hydroxyquinoline)aluminum (Alq3) and 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPD). Molecular ions produced from Alq3 and NPD were measured by linear-type time-of-flight (TOF) mass spectrometry under 5.5 keV Ar70) ion bombardment. The organic multilayer films were analyzed and etched with large Ar cluster ion beams, and the interfaces between the organic layers were clearly distinguished. The effect of temperature on the diffusion of these materials was also investigated by the depth profiling analysis with Ar cluster ion beams. The thermal diffusion behavior was found to depend on the specific materials, and the diffusion of Alq3 molecules was observed to start at a lower temperature than that of NPD molecules. These results prove the great potential of large gas cluster ion beams for molecular depth profiling of organic multilayer samples.

Precise and fast secondary ion mass spectrometry depth profiling of polymer materials with large Ar cluster ion beams.

We demonstrate depth profiling of polymer materials by using large argon (Ar) cluster ion beams. In general, depth profiling with secondary ion mass spectrometry (SIMS) presents serious problems in organic materials, because the primary keV atomic ion beams often damage them and the molecular ion yields decrease with increasing incident ion fluence. Recently, we have found reduced damage of organic materials during sputtering with large gas cluster ions, and reported on the unique secondary ion emission of organic materials. Secondary ions from the polymer films were measured with a linear type time-of-flight (TOF) technique; the films were also etched with large Ar cluster ion beams. The mean cluster size of the primary ion beams was Ar(700) and incident energy was 5.5 keV. Although the primary ion fluence exceeded the static SIMS limit, the molecular ion intensities from the polymer films remained constant, indicating that irradiation with large Ar cluster ion beams rarely leads to damage accumulation on the surface of the films, and this characteristic is excellently suitable for SIMS depth profiling of organic materials.

Matrix-free high-resolution imaging mass spectrometry with high-energy ion projectiles.

The importance of imaging mass spectrometry (MS) for visualizing the spatial distribution of molecular species in biological tissues and cells is growing. We have developed a new system for imaging MS using MeV ion beams, termed MeV-secondary ion mass spectrometry (MeV-SIMS) here, and demonstrated more than 1000-fold increase in molecular ion yield from a peptide sample (1154 Da), compared to keV ion irradiation. This significant enhancement of the molecular ion yield is attributed to electronic excitation induced in the near-surface region by the impact of high energy ions. In addition, the secondary ion efficiency for biologically important compounds (>1 kDa) increased to more than 10(10) cm(-2), demonstrating that the current technique could, in principle, achieve micrometer lateral resolution. In addition to MeV-SIMS, peptide compounds were also analyzed with cluster-SIMS and the results indicated that in the former method the molecular ion yields increased substantially compared to the latter. To assess the capability of MeV-SIMS to acquire heavy-ion images, we have prepared a micropatterned peptide surface and successfully obtained mass spectrometric imaging of the deprotonated peptides (m/z 1153) without any matrix enhancement. The results obtained in this study indicate that the MeV-SIMS technique can be a powerful tool for high-resolution imaging in the mass range from 100 to over 1000 Da.

Successful surgical repair of delayed chronic type a dissection after previous coronary artery bypass grafting.

This reports a case of a 68-year-old woman who had undergone coronary artery bypass 5 years previously. Magnetic resonance angiography (MRA) revealed that the ascending aorta was dilated to about 8 cm in diameter, with type A dissection, and with a patent left internal thoracic artery (LITA) graft to the left anterior descending artery (LAD). Angiography at the ascending aorta did not reveal a coronary artery, nor did it show the sequential saphenous vein graft (SVG) to the obtuse marginal and posterolateral branches. Although the risk of surgical treatment via repeat median sternotomy was very high, we successfully performed the reoperation using profound hypothermic circulatory arrest. The dissection in the mediastinum was facilitated by a sternum retractor for ITA-graft dissection, intraoperative surface echocardiography, and ultrasonic scalpel, with a widely opened bilateral pleural cavity. Furthermore, assuming that most of the myocardium was maintained by perfusion from the in-situ, patent, ITA graft, it was thought that cardioplegia was not necessary during profound hypothermic circulation.

Early results of aortic connector system for proximal anastomosis of the saphenous vein graft.

PURPOSE: Our objective is to clarify the technical points in using the symmetry aortic connector system (ACS) compared with hand-sewing from clinical and angiographic results of the patients who underwent off-pump coronary artery bypass grafting (CABG). METHODS: Among 84 patients who underwent CABG from January 2002 to August 2003, 36 off-pump CABGs were performed using at least one saphenous vein graft (SVG). Thirty proximal anastomosis of 17 patients were performed by ACS, and 30 proximal anastomosis of 19 patients were performed by hand-sewing under aortic side-clamping. Angiogram of the coronary arteries and grafts was carried out 18 days after the operation. RESULTS: Comparing the preoperative characteristics and intraoperative characteristics between the ACS group and hand-sewing group, revealed no significant factors at all. Postoperative angiography of coronary arteries and grafts revealed that the four SVGs with ACS were occluded probably because of kinking near the proximal anastomosis site. On the other hand, all SVGs anastomosed by hand-sewing were patent. CONCLUSION: ACS is very useful with easy handling during off-pump CABG, but it has potential limitations. In our limited experience, we have to mind the graft length as well as the position of proximal anastomosis so that the graft does not kink.

Sutureless patch repair for small blowout rupture of the left ventricle after myocardial infarction.

Rupture of the left ventricular free wall is one of the most serious complications of myocardial infarction. A 73-year-old man with severe chest pain visited our hospital. Coronary angiography revealed acute myocardial infarction in the territory of the diagonal branch. About six hours after successful percutaneous coronary intervention, the patient fell into cardiogenic shock with chest pain. Echocardiography showed moderate pericardial effusion with a subepicardial hematoma, and percardioentesis led to the diagnosis of free wall rupture. Emergency surgery was performed with the use of intra-aortic balloon pumping. The rupture was a blowout type in a small tear at the anterolateral wall of the left ventricle. We repaired the tear with an off-pump sutureless patch using collagen fleece with fibrinogen-based impregnation (TachoComb) and equinous pericardium with fibrin spray. The patient was free of both re-rupture and pseudoaneurysm postoperatively, and was discharged 20 days after the operation. Considering previously reported various procedures for surgical repair, this technique may be useful if the tear is small.

Off-pump redo coronary artery bypass grafting from descending aorta to the posterolateral area through a left thoracotomy in patients with a patent internal thoracic artery graft.

The patients were a 73-year-old man (Case 1) and 56-year-old man (Case 2) who developed angina pectoris and heart failure. Case 2 showed chronic renal failure on hemodialysis. These patients showed posterolateral myocardial ischemia with a patent internal thoracic artery graft to the left anterior descending artery. Left ventricle ejection fraction was 29% and 33%, respectively. Catheter intervention was unsuccessful, so we performed revascularization from the descending aorta to coronary arteries with saphenous vein grafts via a left thoracotomy using an off-pump technique. In case 2, proximal anastomosis was constructed with the Symmetric aortic connector. This procedure appeared to be a very safe and useful method as an option for redo coronary artery bypass grafting in the posterolateral area in patients with patent old grafts and poor left ventricular function.

On the inhibitory action of 29 drugs having side effect gynecomastia on estrogen production.

To examine the influence on aromatase and sulfatase pathways in estrogen pool by drugs reported to cause gynecomastia as the side effect, 29 ethical drugs were incubated with human placental microsomes as an enzyme source. The percent inhibition of drugs on aromatase pathway was obtained by sum of the velocity constants of two products, estrone (E1) and estradiol (E2) from testosterone (T) as the substrate, and that on sulfatase pathway was obtained as the velocity constant of production of E1 from estrone sulfate (E1S). Although several drugs including ketoconazole showed a significant inhibition effect on aromatase pathway at their non-clinical over-dose concentration (100 microM), no influence on the inhibition was observed in any drugs at their approximately therapeutic concentration (1 microM). However, several drugs including spironolactone gave the product ratio (E2/E1) having higher value than that of the control, the result means spironolactone inhibits the conversion of E2 to E1. No inhibitory effect of the drugs tested on estrogen production from E1S (sulfatase pathway) was confirmed. The results suggest the possibility that the tested drugs known to cause gynecomastia have no inhibitory effect essentially on aromatase and sulfatase pathways.