Rapid analysis of N‐linked oligosaccharides in glycoproteins (ovalbumin,ribonuclease B and fetuin) by reversed‐phase ultra‐performance liquid chromatography with fluorescence detection and electrospray ionization time‐of‐flight mass spectrometry

Rapid, selective and sensitive determination of N‐linked oligosaccharides in glycoproteins (ovalbumin, ribonuclease B and fetuin) was performed by ultra‐performance liquid chromatography (UPLC) with fluorescence (FL) and electrospray ionization time‐of‐flight mass spectrometry (ESI‐TOF‐MS). The asparaginyl‐oligosaccharide moiety was first liberated from each glycoprotein by pronase E (a proteolitic enzyme). The oligosaccharide fractions separated by gel‐permeation chromatography were labeled with 1‐pyrenesulfonyl chloride (PSC, a fluorescence reagent), separated by UPLC in a short run time, and then detected by FL and TOF‐MS. The PSC‐labeled oligosaccharides were selectively identified from the FL detection and then sensitively determined by ESI‐TOF‐MS. As the results, 15, eight and four kinds of N‐linked oligosaccharides were detected from ovalbumin, ribonuclease B and fetuin, respectively. Because the present method is rapid (within 9 min), selective and sensitive (approximate 60 fmol, S/N = 5), the determination of N‐linked oligosaccharides in various glycoproteins seems to be possible. Copyright © 2008 John Wiley & Sons, Ltd.     

A Biosensor Composed of Glucose Oxidase‐Containing Liposomes and MnO2‐Based Layered Nanocomposite

Glucose oxidase (GOD) was encapsulated in liposomes, and then the GOD‐containing liposomes were immobilized to a MnO₂‐based multilayered nanocomposite film grown electrochemically. Oxidation of glucose took place on the encapsulated GOD in the manganese oxide film, and the generated H₂O₂ molecules were oxidized catalytically at high valent Mn sites (4+) in the film. Anodic currents due to reoxidation of the reduced Mn ions (3+) were in proportion to the concentration of glucose from 19.6 to 107.1 mM. Such a simple construction of biosensor is applicable to a variety of combinations of liposomal enzymes and substrates.     

High-pressure water vapor treatment for poly-crystalline germanium thin films

We have investigated the high-pressure water (H₂O) vapor treatment for poly-crystalline Ge (poly-Ge) thin films, which were prepared by solid phase crystallization. The optical-absorption coefficients of poly-Ge were reduced by the treatment, suggesting that the grain-boundary defects were successfully passivated. But the poly-Ge films were sometimes damaged by the treatment in higher pressure and temperature. Compromised conditions should be pursued between the effective passivation and avoiding the damage. The rapid cooling after the treatment promotes defect passivation but causes structural distortion. The results show that the high-pressure H₂O vapor treatment is an effective method for the defect passivation of poly-Ge films.     

Quantum spin fluctuations in the spin-liquid state of Tb?Ti?O?

Neutron scattering experiments on a polycrystalline sample of the frustrated pyrochlore magnet Tb(2)Ti(2)O(7), which does not show any magnetic order down to 50 mK, have revealed that it shows condensation behavior below 0.4 K from a thermally fluctuating paramagnetic state to a spin-liquid ground state with quantum spin fluctuations. Energy spectra change from quasielastic scattering to a continuum with a double-peak structure at energies of 0 and 0.8 K in the spin-liquid state. Specific heat shows an anomaly at the crossover temperature.     

Decomposition of organoarsenic compounds for total arsenic determination in marine organisms by the hydride generation technique

The conditions necessary for the complete decomposition of six organic arsenic compounds, namely methylarsonic acid (MMAA), dimethylarsinic acid (DMAA), trimethylarsine oxide, tetramethylarsonium iodide, arsenocholine bromide (AsC) and arsenobetaine (AB), were investigated. The degree of decomposition of the arsenic compounds was monitored using a hydride generation (HYD) technique, because the response from this system depends strongly on the chemical species of arsenic, with inorganic arsenic (the expected product from these decomposition experiments) giving a much more intense HYD signal than the organic arsenic compounds. The arsenic compounds were decomposed by heating them with three types of acid mixture, namely HNO₃? HClO₄, HNO₃? HClO₄? HF, or HNO₃? HClO₄? H₂SO₄. Both MMAA and DMAA were decomposed completely using any of the mixed acids at a decomposition temperature of 200 °C or higher. The HNO₃? HClO₄? H₂SO₄ mixture was the most effective for decomposing AsC and AB, which are the most difficult compounds among all types of organic arsenic compound to decompose and render inorganic. The complete decomposition of AB was only achieved, however, when the temperature was 320 °C or higher, and the sample was evaporated to dryness. When the residue from this treatment was examined by high‐performance liquid chromatography combined with inductively coupled plasma atomic emission spectrometry, all of the arsenic was found to be present as arsenic(V). The optimized conditions (HNO₃? HClO₄? H₂SO₄ at 320 °C) for decomposing AB were then used to determine the total amount of arsenic in marine organisms known to contain AB. Copyright © 2005 John Wiley & Sons, Ltd.     

Forensic discrimination of sheet glass by a refractive-index measurement and elemental analysis with synchrotron radiation X-ray fluorescence spectrometry.

Measurements of the refractive index (RI) and elemental analysis using synchrotron radiation X-ray fluorescence spectrometry (SR-XRF) were applied to the forensic discrimination of sheet-glass samples from different origins. The refractive index was calculated from the matching temperature at which the glass fragments became invisible in silicone oil. Fragments smaller than 1 mm in maximum diameter were taken from each of 11 sheet glasses and subjected to analysis by SR-XRF. The XRF spectrum of these samples indicated that a comparison of 6 elements (Ca, Fe, Sr, Zr, Ba and Ce) was useful for the discrimination of sheet glasses. Cluster analysis was performed using 33 sets of SR-XRF data obtained by triplicate measurements for the 11 glasses. Comparing 528 pairs among 33 samples, 515 pairs could be correctly discriminated. The number of indistinguishable pairs could be reduced from 36 to 4 by comparing the SR-XRF data. Elemental analysis by SR-XRF could provide small glass fragments with a more evidential value than the solely measurement of only RI, through a significant improvement of the discrimination capability.